JP3671250B2 - Diamond grinding wheel and its truing device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a diamond grinding wheel and a truing device for a diamond grinding wheel.
[0002]
[Prior art]
FIG. 17 (a) is a diagram showing the outer shape of a metal bond diamond grinding wheel before truing, FIG. 17 (b) is a diagram showing the outer shape of the metal bond diamond grinding wheel after truing, and FIG. 18 is a diagram of the diamond grinding wheel before truing. It is a schematic diagram which shows the cutting blade state of an abrasive grain.
[0003]
In general, to suppress the rotational runout V of the grinding wheel and to correct the shape of the grinding wheel is called truing, and to remove the bond and project abrasive grains is called dressing. As shown in FIGS. 17A and 18, the diamond grinding wheel 3 before truing does not have the same cutting edge height of the diamond abrasive grain 1, that is, the height of the tip of the diamond abrasive grain 1.
[0004]
By the way, as a conventional truing method of a diamond grinding wheel, there are a method of processing a target grinding wheel using a GC grinding wheel (silicon carbide type grinding stone) as a tool, a method of processing a dressing grinding stone, a method of melting a bond by an electric discharge action, and the like. These are described in "Research on Truing of Vitrified Diamond Grinding Wheel" (Proceedings of Academic Lectures of the Spring Meeting of the Japan Society for Precision Engineering 1987) and "Basic Research on Electrolytic Discharge Dressing" (Proceedings of the Academic Lectures of the Spring Meeting of the 1990 Precision Engineering Society). As described above, this is a drop-out truing method in which the abrasive grains are dropped off by removing the bond to remove the rotational runout of the grinding wheel.
[0005]
FIG. 19 is a schematic view of the surface state of a diamond grinding wheel trued by a conventional truing method (drop-off truing method).
[0006]
In this conventional truing method, the bond 2 'is removed by truing, the diamond abrasive grains 1' supported by the bond 2 'drop off, and the diamond grains 1' protruding excessively are removed. However, in this truing method, the hardness of the abrasive grains as a tool is lower than the hardness of the diamond abrasive grains 1 to be processed, and the diamond abrasive grains 1 cannot be processed.
[0007]
On the other hand, in ultra-precision grinding of brittle materials, which has been attracting attention in recent years, the goal is to achieve nanometer-order shape accuracy and surface roughness. In order to achieve this target, it is necessary to perform processing under processing conditions in which the cutting depth per abrasive grain is equal to or less than the critical cutting depth. By the way, it is known that when a brittle material is ground, it is processed in a brittle mode while generating cracks. However, it has been found that, by controlling the cutting depth of the abrasive grains to a very small amount, the brittle material can be processed in a ductile mode that does not generate cracks, like a metal. The boundary between the ductile mode and the brittle mode is called a critical cutting depth (dc value), which is said to be about 0.1 μm although it varies depending on the material. For this purpose, the cutting edge state of the grinding wheel needs to suppress the rotational runout of the grinding wheel to the order of submicron or less and make the cutting edge height of the abrasive grains uniform.
[0008]
20 is a perspective view of the magnetic head, and FIG. 21 is an enlarged view of a portion S in FIG.
[0009]
On the other hand, the accuracy of magnetic heads has been increasing in recent years, and in particular, there has been a demand for higher accuracy of shape and reduction of processing steps. Currently, lapping is used for finishing the air bearing surface, which is the surface facing the recording medium, in the magnetic head 4 shown in FIG. However, since lapping is a processing method based on the pressure transfer principle, an edge portion having a high processing pressure is likely to be processed quickly. For this reason, since the edge falls, it is difficult to obtain high shape accuracy. Further, since loose abrasive grains are used in lapping, the magnetic film 7 (Hv = Hv = 1000) is compared with the hardness of the substrate 5 (Vickers hardness Hv = 1300) and the protective film 6 (Hv = 1000) shown in FIG. 200) is soft and is processed quickly, resulting in a processing step A. On the other hand, if the air bearing surface of the magnetic head 4 can be processed by grinding, which is a processing method based on the motion transfer principle, in principle, it can be processed with higher shape accuracy than lapping. Can set the processing step to zero. However, a problem when replacing lapping with grinding is that the surface roughness due to grinding is worse than the surface roughness due to lapping.
[0010]
Therefore, the following points are required for a diamond grinding wheel in order to process a magnetic head with high shape accuracy and good surface roughness by grinding.
[0011]
That is, diamond abrasive grains are bonded with a metal bond having high support rigidity, rotational runout of the grinding wheel is suppressed to the submicron order, and the cutting edge height of the abrasive grains is made uniform.
[0012]
[Problems to be solved by the invention]
The conventional truing method is a so-called detachable truing method in which abrasive bonds are removed by truing and the abrasive grains supported by the bonds are dropped, and in this method, the hardness of the abrasive grains as a tool is Since the hardness of the diamond abrasive grains to be processed is low, the diamond abrasive grains cannot be ground. Therefore, the roundness of the truing diamond grinding wheel is determined by the distribution accuracy of the diamond abrasive grains on the outer peripheral surface of the grinding wheel (the diamond abrasive grains are uniformly distributed in the plane involved in the grinding wheel processing). As shown in FIGS. 7A and 7B, when the abrasive grain size of the grinding wheel is large, there is a problem that the rotational runout of the grinding wheel becomes large. . Even when the abrasive grain size is as small as several μm, the rotational runout of the grinding wheel is 1 μm at most, and there is a problem that the rotational runout cannot be suppressed on the order of submicrons.
[0013]
As described above, in the ultra-precise grinding of a brittle material such as ceramic, the cutting depth per abrasive grain of the grinding wheel must be processed under the processing conditions equal to or less than the critical cutting depth. For this purpose, it is necessary to suppress the rotational runout of the grinding wheel to the order of submicron or less, and to make the heights of the abrasive grains uniform. However, in the conventional truing method, it is not taken into consideration that the heights of the cutting edges of the abrasive grains are made uniform. Therefore, in a grinding wheel trued by the conventional truing method, the cutting depth per abrasive grain is processed under a processing condition that is equal to or less than the critical cutting depth, and processing is performed in a ductile mode without generating cracks in the brittle material. There is a problem that cannot be applied to ultra-precision grinding of brittle materials.
[0014]
Furthermore, in order to grind the surface of the magnetic head that faces the recording medium, it is necessary to perform processing with high shape accuracy and with a processing surface roughness comparable to that of lapping. In order to grind the air bearing surface of the magnetic head to a surface roughness comparable to lapping, diamond abrasive grains are bonded with a metal bond with high support rigidity to form a diamond grinding wheel, and the rotation of this diamond grinding wheel It is necessary to suppress run-out and to align the cutting edge height of the diamond abrasive grains. However, in the conventional truing method, it is not considered to grind a hard diamond grinding wheel itself so as to align the cutting edge height of diamond abrasive grains. Therefore, the diamond grinding wheel trued by the conventional truing method has a problem that it cannot be applied to the grinding process of the surface facing the recording medium in the magnetic head.
[0015]
A first object of the present invention is to provide a diamond grinding wheel in which the work surface has extremely small runout and the cutting edge height of the diamond abrasive grains is precisely aligned.
[0016]
A second object of the present invention is to provide a truing device for a diamond grinding wheel capable of accurately carrying out a truing method for a diamond grinding wheel capable of reliably forming the diamond grinding wheel.
[0017]
[Means for Solving the Problems]
The first object is a diamond grinding wheel in which a large number of diamond abrasive grains are hardened with bonds to form a disk shape, and the working surface of the grinding wheel is round so that the abrasive grains and bonds are substantially flush with each other. The bonded bond is uniformly dressed to a predetermined depth to cause the abrasive grains to protrude from the surface of the dressed bond, and the tip of the protruded abrasive grains is thermally polished. This is achieved by flat and smooth shaping.
[0018]
The first object is a diamond grinding wheel in which a large number of diamond abrasive grains are hardened with a bond to form a cup shape, and the working surface of the grinding wheel is highly accurate so that the abrasive grains and the bond are flush with each other. In addition, a predetermined amount of the ground bond is dressed to cause the abrasive grains to protrude from the surface of the dressed bond, and the tip of the protruded abrasive grains is thermochemically treated. This is achieved by polishing and shaping it flat and smooth.
[0019]
The second object is to provide a first truing device, a dressing device, and a second truing device, and the first truing device is supported by a hydrostatic bearing and bonds a large number of diamond abrasive grains. The main shaft for supporting the diamond grinding wheel hardened in step 1 as a workpiece, the rotational drive source of the main shaft, and the work surface of the diamond grinding wheel as the workpiece are ground so that the diamond abrasive grains and the bond are substantially flush with each other. 1 truing tool, a rotational drive source of the first truing tool, and a cutting means for relatively sending the first truing tool and the diamond grinding wheel as the workpiece in the cutting direction, The dressing apparatus uniformly dresses the ground surface of the bond to a predetermined depth, and the diamond abrasive grains are applied. A main shaft configured to protrude from the surface of the dressed bond, the second truing device being supported by a hydrostatic bearing and supporting the dressed diamond grinding wheel as a workpiece, and a rotational drive source of the main shaft; A second truing tool for thermochemically polishing the tip of each diamond abrasive grain protruding from the surface of the dressed bond in a flat and smooth manner to align the cutting edges, and rotational driving of the second truing tool This is achieved by comprising a source, and a cutting means for relatively feeding the second truing tool and the diamond grinding wheel as the workpiece in the cutting direction.
[0020]
Further, the second object is to selectively attach the first truing tool and the second truing tool to a single truing device, and attach the single truing device to the first truing device and the second truing device. This can also be achieved by combining the truing device with this.
[0021]
Further, the third object is to fix the position of the main shaft that supports a diamond grinding wheel as a workpiece, and to set the first truing tool, the dressing device, and the second truing tool to a machining position with respect to the workpiece, respectively. This is better achieved by being configured to be movable to the retracted position.
[0022]
Furthermore, the third object is to use a cup-type metal bond diamond grindstone as the first truing tool and to use a cup-type iron-based metal surface plate as the second truing tool. Further, the dressing device further includes an electrode disposed at a predetermined interval with the diamond grinding wheel, a power source that connects the anode to the diamond grinding wheel as a workpiece and the cathode to the electrode, This is better achieved by comprising the rotational drive source of the diamond grinding wheel.
[0023]
[Action]
According to the first aspect of the present invention, the outer peripheral surface, which is a work surface of a disk-type diamond grinding wheel in which a large number of diamond abrasive grains are hardened with bonds, is formed into a perfect circle so that the abrasive grains and the bonds are substantially flush with each other. Therefore, the rotational runout of the diamond grinding wheel during use can be suppressed to a submicron order. The ground bond is uniformly dressed to a predetermined depth so that the abrasive grains protrude from the surface of the dressed bond, and the tip portion of the protruded abrasive grains is thermochemically polished and flattened. And since it is shaped smoothly, the cutting edge height of diamond abrasive grains can be precisely aligned. Therefore, the diamond grinding wheel according to the first aspect can be applied to ultra-precision grinding of a brittle material and grinding finishing of a surface facing a recording medium in a magnetic head.
[0024]
Next, in the invention according to claim 2, a high-precision flat surface is formed so that the end surface, which is a work surface of a cup-type diamond grinding wheel in which a large number of diamond abrasive grains are hardened with bonds, is the same surface. Therefore, the vibration of the working surface of the diamond grinding wheel during use can be suppressed to the order of submicrons. Further, similarly to the diamond grinding wheel according to claim 1, the ground bond is uniformly dressed to a predetermined depth so that abrasive grains are projected from the dressed bond surface, and the diamond grinding is further projected from the bond surface. Since the tips of the grains are polished by thermochemically and are shaped flat and smooth, the cutting edge height of the diamond abrasive grains can be made uniform. As a result, the diamond grinding wheel according to claim 2 can also be applied to ultra-precision grinding of brittle materials and grinding finishing of the surface of the magnetic head facing the recording medium.
[0025]
In invention of Claim 3, the 1st truing apparatus, the dressing apparatus, and the 2nd truing apparatus are arranged.
[0026]
The first truing device grinds a main shaft supported by a hydrostatic bearing, a rotational drive source of the main shaft, and a work surface of a diamond grinding wheel as a workpiece so that diamond abrasive grains and bonds are substantially flush with each other. A first truing tool, a rotational drive source for the first truing tool, and a cutting means for relatively sending the first truing tool and a diamond grinding wheel as a workpiece in the cutting direction. And the diamond grinding wheel which is a workpiece | work is attached to the main axis | shaft of this 1st truing apparatus, and a main axis | shaft and a 1st truing tool are each rotated with an independent rotational drive source. Next, the diamond grinding wheel or the first truing tool is fed in small amounts in the direction of cutting the work surface of the diamond grinding wheel via the cutting means. As a result, when the workpiece is a disk-type diamond grinding wheel, the outer peripheral surface, which is the work surface, and when the workpiece is a cup-type diamond grinding wheel, the end surface, which is the work surface, is set to the first truing. It can be ground by a minute amount with a tool. When grinding the work surface of the diamond grinding wheel with the first truing tool, the main shaft is strongly supported by the hydrostatic bearing and does not escape in the direction opposite to the cutting direction. Since the first truing tool is directly rotated by the rotary driving source, even if the diamond grinding wheel and the first truing tool are in frictional contact with each other, each is determined. Because it rotates with high precision in the direction, the part that protrudes from the work surface of the diamond grinding wheel can be reliably ground with the first truing tool. If the workpiece is a disk-type diamond grinding wheel, If the workpiece is a cup-type diamond grinding wheel, the end surface, which is the work surface, is raised. It can be shaped to the plane of the time.
[0027]
Next, the diamond grinding wheel shaped by the first truing device is attached to the dressing device. With this dressing apparatus, the bond surface is uniformly removed to a predetermined depth, and diamond abrasive grains are projected onto the bond surface.
[0028]
Next, the second truing device flattenes and smoothes the main shaft supported by the hydrostatic bearing, the rotational drive source of the main shaft, and the tip of the diamond abrasive grains protruding from the surface of the dressed bond. A second truing tool for thermochemical polishing; a rotational drive source of the second truing tool; and a cutting means for relatively sending the second truing tool and a diamond grinding wheel as a workpiece in a cutting direction. I have. Therefore, the diamond grinding wheel dressed by the dressing device is attached to the main shaft of the second truing device as a workpiece. Then, the main shaft and the second truing tool are rotationally driven by independent rotational driving sources. Next, the diamond grinding wheel or the second truing tool is fed by a minute amount through the cutting means in the direction of cutting the work surface of the diamond grinding wheel. As a result, the diamond abrasive grains protruding from the surface of the bond are gradually polished by the second truing tool from the most protruding diamond abrasive grain tip, and the tip of each diamond abrasive grain is Polished flat and smooth. Also in this second truing device, the main shaft is strongly supported by the hydrostatic bearing at the time of polishing, so it does not escape in the direction opposite to the cutting direction, and the diamond grinding wheel as the work is driven by the main shaft and its rotational drive. Since the second truing tool is directly rotated by the rotation source, and the second truing tool is directly driven by the rotation driving source, even if the diamond grinding wheel and the second truing tool are in frictional contact with each other, high precision is obtained in each determined direction. The tip of diamond abrasive grains protruding from the surface of the bond can be reliably and accurately polished by the second truing tool, and the cutting edge height of the diamond abrasive grains is precisely aligned. be able to.
[0029]
Therefore, in the invention according to the third aspect, the truing method of the diamond grinding tool according to the present invention can be accurately performed.
[0030]
According to a fourth aspect of the present invention, a first truing tool and a second truing tool are selectively attached to a single truing device, and the single truing device is attached to the first truing device and the second truing device. It is also used as a device.
[0031]
As a result, in the invention according to claim 4, the equipment cost can be reduced and the installation space for the apparatus can be reduced.
[0032]
In a fifth aspect of the present invention, the position of the spindle that supports the workpiece is fixed, and the first truing tool, the dressing device, and the second truing tool can be moved to a machining position and a retracted position, respectively. It is composed. Then, a diamond grinding wheel as a workpiece is attached to the spindle, and when grinding the work surface of the diamond grinding wheel, the first truing tool is moved to the machining position and the target grinding is performed, and then the workpiece is moved to the retracted position. Move. Next, during truing of the surface of the bond of the diamond grinding wheel, the truing device is moved to the processing position to perform the desired truing, and then moved to the retreat position. Next, when polishing the tip of each diamond abrasive grain protruding from the surface of the bond, the second truing tool is moved to the processing position to perform the target polishing, and then moved to the retreat position.
[0033]
In the invention according to claim 5, each diamond protruded from the surface of the bond, the grinding of the work surface of the diamond grinding wheel, the dressing of the bond surface, and the diamond grinding wheel as the work attached to the main shaft Since the polishing of the tip of the abrasive grains is performed sequentially, it is possible to eliminate workpiece mounting errors, so that processing can be performed with extremely high accuracy, and the above-described processing can be performed continuously. As a result, work efficiency can be improved.
[0034]
In the invention described in claim 6, a cup-type metal bond diamond grindstone is used as the first truing tool, and in the invention described in claim 7, a cup-type iron-based metal surface plate is used as the second truing tool. Used.
[0035]
As a result, both the inventions according to claims 6 and 7 can accurately true a diamond grinding wheel which is a hard workpiece.
[0036]
In the invention according to claim 8 of the present invention, the dressing apparatus includes an electrode arranged at a predetermined interval between the workpiece and the diamond grinding wheel, and an anode connected to the diamond grinding wheel as the workpiece and a cathode. A power source connected to the electrode and a rotational drive source of the diamond grinding wheel are provided.
[0037]
Therefore, in the invention according to claim 8, even when a metal bond having a high support rigidity is used as the bond, the metal bond is electrolyzed and the surface of the bond is maintained without breaking the cutting edge state of the diamond abrasive grains. Can be removed uniformly, and the cutting edge of the abrasive grain, which is the tip of the diamond abrasive grain, can be easily protruded from the surface of the bond.
[0038]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0039]
1 to 6 show an embodiment of the present invention, and FIGS. 1A, 1B, and 1C show the concept of a truing method according to the diamond grinding wheel of the present invention and the truing apparatus for a diamond grinding wheel. FIG. 2 is a front view of the first truing device in the truing device of the present invention, FIG. 3 is a central longitudinal side view of FIG. 2, FIG. 4 is a conceptual diagram of an electrolytic dressing device in the truing device, and FIG. FIG. 6 is an enlarged view of a Q portion, and is an explanatory view of the action of the electrolytic dressing, and FIG. 6 is a front view of a second truing device in the truing device.
[0040]
In the embodiments shown in these drawings, the truing device is configured by arranging a first truing device 10, a dressing device, and a second truing device 21 as shown in FIGS. . In this embodiment, a diamond grinding wheel 3 is formed as a work, in which diamond abrasive grains are hardened with metal bonds and formed into a disk shape.
[0041]
The first truing device 10 supports a feed table 11, a tool support 12, a first truing tool 13, a rotational drive source (not shown), a main shaft 14, and the main shaft 14. A hydrostatic bearing 15, a rotational drive source (not shown) of the main shaft 14, a cutting means (not shown) for feeding the diamond grinding wheel 3 through the main shaft 14, and a grinding fluid supply means (this) (Not shown).
[0042]
The truing table 11 is configured to move the first truing tool 13 in the direction of the arrow in FIG. 2 via the tool support 12 during truing, and the feeding speed is indicated by a symbol f.
[0043]
The first truing tool 13 is a cup-type diamond grindstone. The first truing tool 13 is disposed in a direction orthogonal to the main shaft 14 and is supported on the tool support 12. Further, the first truing tool 13 is directly driven to rotate in the direction of the arrow in FIG.
[0044]
A diamond grinding wheel 3 as a workpiece is mounted on the main shaft 14 via a flange 8, and the diamond grinding wheel 3 is stopped by a clamp 9 as shown in FIG. 3. The main shaft 14 is supported by a hydrostatic bearing 15 and is directly driven to rotate in the direction of the arrow in FIG. 2 by a rotational drive source.
[0045]
As the hydrostatic bearing 15, a hydrostatic air bearing or a hydrostatic oil bearing is used.
[0046]
During the truing, the cutting means applies a minute feed to the diamond grinding wheel 3 through the main shaft 14 in the radial direction of the disk-shaped diamond grinding wheel 3 as a workpiece as indicated by an arrow in FIG. The depth of cut for one time is indicated by the symbol d.
[0047]
The grinding fluid supply means is arranged so as to supply the grinding fluid between the first truing tool 13 and the diamond grinding tool 3 as a workpiece.
[0048]
In this embodiment, an electrolytic dressing device 16 is used as the dressing device. As shown in FIG. 4, the electrolytic dressing device 16 includes an electrode 17, a DC power source 18 as a power source, a means for supplying a grinding liquid 19, and a rotational drive source (not shown) for the diamond grinding wheel 3 as a workpiece. And.
[0049]
The electrode 17 is disposed at a predetermined interval g between the outer periphery of the diamond grinding wheel 3 as a workpiece.
[0050]
The DC power source 18 has an anode connected to the diamond grinding wheel 3 and a cathode connected to the electrode 17.
[0051]
The grinding liquid 19 is supplied to the gap between the diamond grinding wheel 3 and the electrode 17.
[0052]
The rotational drive source rotationally drives the diamond grinding tool 3 in the direction of arrow e in FIG. 4 during dressing.
[0053]
In the electrolytic dressing device 16, when the diamond grinding wheel 3 and the electrode 17 are energized from the DC power source 18, the metal bonds of the diamond abrasive grains are electrolyzed and removed as metal ions 20 as shown in FIG. It has become so.
[0054]
As shown in FIG. 6, the second truing device 21 includes a feed table 22, a tool support 23, a second truing tool 24, a rotational drive source (not shown), a main shaft 25, and the like. A hydrostatic bearing (not shown) supporting the main shaft 25, a rotational drive source (not shown) of the main shaft 25, and a notch means for sending the diamond grinding wheel 3 through the main shaft 25 (also shown in FIG. Not shown).
[0055]
The feed table 22 is configured to move the second truing tool 24 in the direction of the arrow in FIG. 6 via the tool support 23 during truing, and the feed speed is indicated by a symbol f.
[0056]
For the second truing tool 24, a cup-shaped surface plate made of cast iron, which is an iron-based metal, is used. The second truing tool 24 is disposed in a direction orthogonal to the main shaft 25 and supported by the tool support 23. The truing tool 24 is directly driven to rotate in the direction of the arrow in FIG.
[0057]
A diamond grinding wheel 3 dressed by the dressing device as a work is mounted on the main shaft 25 via a flange 8 and is fixed by a clamp 9. The main shaft 25 is supported by a hydrostatic bearing, and is further directly driven to rotate in the direction of the arrow in FIG. 6 by a rotational drive source.
[0058]
The hydrostatic bearing is the same as the hydrostatic bearing 15 of the main shaft 14 of the first truing device 10.
[0059]
During the truing, the cutting means applies a minute feed to the diamond grinding wheel 3 through the main shaft 25 in the radial direction of the diamond grinding wheel 3 as a workpiece as indicated by an arrow in FIG. The depth of cut for one time is indicated by symbol d.
[0060]
Next, in relation to the operation of the truing apparatus of the above embodiment, the truing method and the diamond grinding wheel which is the product will be described.
[0061]
First, a diamond grinding wheel 3, which is a workpiece formed by solidifying diamond abrasive grains with metal bonds into a disk shape, is connected to the main shaft 14 of the first truing device 10 shown in FIG. 2 and FIG. Install and stop with clamp 9.
[0062]
Next, the first truing tool 13 is rotated in the direction of the arrow in FIG. 2, and the diamond grinding wheel 3 is rotated in the direction of the arrow in FIG. Moreover, the diamond grinding wheel 3 is fed in the direction of the arrow in FIG. 2 by the cutting means via the main shaft 14, and the most protruding portion of the outer peripheral surface of the diamond grinding wheel 3 contacts the upper surface of the first truing tool 13. Set to do. Then, the grinding fluid is supplied between the first truing tool 13 and the diamond grinding tool 3 by the grinding fluid supply means. Next, automatic fine feed is applied to the diamond grinding wheel 3 in the direction of the arrow by the cutting means. Further, the feed table 11 is moved minutely in the direction of the arrow in FIG.
[0063]
Thereby, the outer peripheral surface of the diamond grinding wheel 3 as a workpiece is ground by the first truing tool 13 as a diamond grinding stone. At this time, as shown in FIG. The entire diamond grinding wheel 3 is ground into a perfect circle by a so-called machining type truing method.
[0064]
During grinding of the diamond grinding wheel 3, the main shaft 14 is strongly supported by the hydrostatic bearing 15 and does not escape in the direction opposite to the cutting direction of the diamond grinding wheel 3. Further, the diamond grinding wheel 3 is directly driven to rotate through the main shaft 14 and its rotation drive source (not shown), and the first truing tool 13 is directly driven to rotate through its rotation drive source (not shown). Even if the diamond grinding wheel 3 and the first truing tool 13 are in frictional contact with each other, the diamond grinding wheel 3 rotates with high accuracy in each determined direction. Therefore, the protruding part on the outer peripheral surface of the diamond grinding wheel 3 can be reliably ground by the first truing tool 13, so that the diamond grinding wheel 3 can be accurately shaped into a perfect circle.
[0065]
As described above, after grinding the diamond grinding wheel 3 into a perfect circle by the machining type truing method, the driving of each part of the first truing device 10 is stopped, and the processed diamond grinding wheel 3 is taken out from the main shaft 14. Each part of the truing device 1 is returned to the initial state.
[0066]
Next, the diamond grinding wheel 3 that has been ground is attached to an electrolytic dressing apparatus 16 shown in FIG. Further, the electrode 17 is arranged with a predetermined gap g shown in FIG. 4 between the workpiece and the diamond grinding wheel 3, the anode of the DC power supply 18 is connected to the diamond grinding wheel 3, and the cathode is connected to the electrode 17. Energize with.
[0067]
Subsequently, a grinding liquid 19 is flowed between the diamond grinding wheel 3 and the electrode 17, and the diamond grinding wheel 3 is rotated in the direction of arrow e in FIG. 4 by a rotation drive source (not shown).
[0068]
As a result, the metal bond 2 of the diamond grinding wheel 3 is electrolyzed and becomes metal ions 20 and uniformly removed from the surface of the metal bond 2 as shown in FIG. Therefore, by this electrolytic dressing, the metal bond 2 can be easily removed without destroying the cutting edge state of the diamond abrasive grain 1, and the tip of the diamond abrasive grain 1 from the surface of the metal bond 2 as shown in FIG. The cutting edge which is a part can be protruded.
[0069]
After dressing the diamond grinding wheel 3, the function of each part of the electrolytic dressing device 16 is stopped, the diamond grinding wheel 3 is removed from the electrolytic dressing device 16, and the electrolytic dressing device 16 is returned to the initial state.
[0070]
Next, the dressed diamond grinding wheel 3 is mounted as a work on the main shaft 25 of the second truing device 21 shown in FIG.
[0071]
Then, the second truing tool 24 is rotated in the arrow direction of FIG. 6, and the diamond grinding tool 3 is rotated in the arrow direction via the main shaft 25. Further, the cutting means feeds the diamond grinding wheel 3 through the main shaft 25 in the direction of the arrow in FIG. 6 and sets the outer surface of the diamond grinding wheel 3 in contact with the upper surface of the second truing tool 24. Thereafter, automatic cutting is applied to the diamond grinding wheel 3 in the direction of the arrow by the cutting means, and the feed table 22 is moved minutely in the direction of the arrow in FIG.
[0072]
As a result, the diamond grinding wheel 3 as a workpiece comes into contact with the second truing tool 24 which is a surface plate made of cast iron, and the diamond abrasive grains 1 of the diamond grinding wheel 3 are rubbed against the second truing tool 24, so-called. The tip of each diamond abrasive grain 1 protruding from the outer peripheral surface of the metal bond 2 is polished by a polishing truing method. That is, when the cast iron surface plate and diamond are rubbed together, a minute amount of the tip of each diamond abrasive grain 1 is removed by a chemical reaction between iron and diamond, in which iron absorbs diamond carbon.
[0073]
As described above, the second truing apparatus 21 uses a polishing type truing method in which the tip of each diamond abrasive grain 1 is polished by the second truing tool 24 using the chemical change between iron and diamond. As shown to (c), the cutting-edge height of the diamond abrasive grain 1 can be arrange | positioned reliably and with high precision.
[0074]
Further, when the diamond grinding wheel 3 is polished, the main shaft 25 is strongly supported by a hydrostatic bearing (not shown) and does not escape in the direction opposite to the cutting direction of the diamond grinding wheel 3. Moreover, the diamond grinding wheel 3 is directly driven to rotate through the main shaft 25 and its rotation drive source (not shown), and the second truing tool 24 is directly driven to rotate by this rotation drive source (not shown). Even if the diamond grinding wheel 3 and the second truing tool 24 are in frictional contact with each other, the diamond grinding wheel 3 rotates with high precision in each determined direction. Therefore, the tip of each diamond abrasive grain 1 protruding from the outer peripheral surface of the metal bond 2 can be reliably polished by the second truing tool 24. As a result, it is possible to precisely align the cutting edge height of each diamond abrasive grain 1 protruding from the outer peripheral surface of the metal bond 2.
[0075]
As described above, after aligning the cutting edge height of the diamond abrasive grains 1 of the diamond grinding wheel 3, the driving of each part of the second truing device 21 is stopped, and the diamond grinding wheel 3 as a product is removed from the spindle 25, Each part of the second truing device 21 is returned to the initial state, and one truing stroke of the diamond grinding wheel 3 is completed.
[0076]
Since the disc-shaped diamond grinding wheel 3 which is a product formed through the above truing process is shaped into a perfect circle by the machining truing method, rotational runout is suppressed to the order of submicrons. Moreover, even if the hard metal bond 2 is used by the electrolytic dressing method, the tip part of the diamond abrasive grain 1 can be protruded by a predetermined amount. In addition, the tip of each diamond abrasive grain 1 protruding from the metal bond 2 is polished by the polishing truing method, the cutting edge height is precisely aligned, and a good machined surface roughness can be obtained. In addition, the cutting edge is shaped into a trapezoid. Therefore, it is possible to immediately apply the diamond grinding wheel 3 which is this product to the processing in the ductile mode of a brittle material and the grinding finish of the surface facing the recording medium in the magnetic head 4 shown in FIG.
[0077]
Next, FIG. 14 is an explanatory diagram of the truing method for a cup-type diamond grinding wheel.
[0078]
In the case of truing the cup-type diamond grinding wheel by the truing method according to the truing apparatus for the diamond grinding wheel of the present invention, the end surface 31 which is the working surface of the diamond grinding wheel 30 is first ground into a high-precision plane, Then, the surface of the bond on the end face 31 is dressed, and then the tip of each diamond abrasive grain protruding from the bond surface on the end face 31 is polished.
[0079]
First, in order to grind the end face 31 of the diamond grinding wheel 30 as a workpiece, a truing device that supports the main shaft 14 of the first truing device 10 of the embodiment shown in FIG. 2 in the vertical direction is used. In the embodiment shown in FIG. 14, the diamond grinding wheel 30 is attached to the main shaft (not shown) with the end surface 31 to be trued downward and eccentric to the axis of the first truing tool 13. The first truing tool 13 is a diamond grindstone having a larger abrasive grain size than the diamond abrasive grain size of the diamond grinding wheel 30 as a workpiece.
[0080]
Next, the diamond grinding wheel 30 is rotated in the direction of the arrow i through the main shaft and its rotational drive source (none of which is shown), and the first truing tool 13 is passed through its rotational drive source (not shown). While rotating in the direction of arrow h, the most protruding portion of the end surface 31 of the diamond grinding wheel 30 is brought into contact with the upper surface of the first truing tool 13. The peripheral speed of the first truing tool 13 is made faster than the peripheral speed of the diamond grinding wheel 30. In addition, after the end surface 31 of the diamond grinding tool 30 is brought into contact with the upper surface of the first truing tool 13, the diamond grinding tool 30 is automatically cut and fed by a minute amount so that the end surface 31 of the diamond grinding tool 30 is raised. Grind to a precision plane.
[0081]
Next, the diamond grinding wheel 30 whose end face 31 is ground to a high-precision plane is uniformly removed by a dressing device (not shown), and a predetermined amount of the tip of the diamond abrasive grains is removed from the bond surface. Let it stick out. When the bond is a metal bond, the surface of the metal bond can be easily and uniformly removed by electrolysis by using the electrolytic dressing apparatus 16 shown in FIG.
[0082]
Next, in order to polish the tip portion of each diamond abrasive grain protruding from the surface of the bond by dressing, a truing device that supports the main shaft 25 of the second truing device 21 of the embodiment shown in FIG. 6 in the vertical direction is used. use. As the second truing tool 24, a cup-shaped surface plate made of cast iron is used as shown in FIG. Then, the diamond grinding wheel 30 as a workpiece is attached to the main shaft so that the end surface 31 to be trued is directed downward and is eccentric with respect to the axis of the second truing tool 24. Next, the diamond grinding wheel 30 is rotated through the main shaft and its rotational drive source (both not shown), and the second truing tool 24 is rotated through the rotational drive source (not shown). After rotating at a peripheral speed faster than the peripheral speed of 30 and bringing the most protruding diamond abrasive grains out of a large number of diamond abrasive grains into contact with the upper surface of the second truing tool 24, the diamond grinding wheel 30 is automatically Apply cutting feed, polish the tip of each diamond abrasive grain, and align the cutting edge height of diamond abrasive grains with high accuracy.
[0083]
Through the above steps, also in the cup-type diamond grinding wheel 30, the end surface 31 that is the work surface can be trued as shown in FIGS. 1 (a), (b), and (c). Therefore, the cup-type diamond grinding wheel can be trued so that, when used, the runout of the end face, which is the work surface, is suppressed to the order of submicrons, and a good machined surface roughness can be obtained.
[0084]
Next, FIG. 15 is an explanatory diagram of the truing method for a diamond grinding wheel with a shaft.
[0085]
In the truing method of the diamond grinding wheel with a shaft, when the outer peripheral surface 33 or the annular edge 34 is truing as a work surface of the diamond grinding wheel 32 with a shaft shown in FIG. To do. Further, when the end surface 35 is trued as the work surface of the shaft-equipped diamond grinding wheel 32, the same process as the cup-type diamond grinding wheel 30 is performed. Thereby, also in the diamond grinding wheel 32 with a shaft, the outer peripheral surface 33, the annular edge 34, or the end surface 35, which is the work surface, can be trued as shown in FIGS. it can.
[0086]
Proceeding, FIG. 16 is a front view of another embodiment of the truing device of the present invention.
[0087]
The truing device of the embodiment shown in FIG. 16 is intended for the disk-type diamond grinding wheel 3, and includes a main shaft 14, a first truing tool 13, an electrolytic dressing device 16, and a second truing tool (see FIG. 16). (Not shown).
[0088]
2 and 3, the main shaft 14 is supported by a hydrostatic bearing and is driven to rotate by an independent rotational drive source. Further, the position of the main shaft 14 is fixed.
[0089]
The first truing tool 13 is supported by the tool support 12 and is rotationally driven by an independent rotational drive source, as shown in FIGS. The tool support 12 is mounted on the feed table 11. The first truing tool 13 is installed so as to be movable between a machining position with respect to the diamond grinding wheel 3 which is a work supported by the main shaft 14, that is, a machining truing position and a retreat position.
[0090]
The electrolytic dressing device 16 includes an electrode 17, a DC power source 18, and a means for supplying a grinding liquid 19, as shown in FIG. 4. Each member of the electrolytic dressing device 16 is also movably installed at a processing position with respect to the diamond grinding wheel 3 supported by the main shaft 14, that is, a position where electrolytic dressing is performed and a retreat position.
[0091]
Similar to the one shown in FIG. 6, the second truing tool is supported on a tool support and is rotationally driven by an independent rotational drive source. The tool support is mounted on a feed table. The second truing tool is also installed so as to be movable between a processing position for the diamond grinding wheel 3 supported by the main shaft 14, that is, a polishing truing position and a retracted position.
[0092]
When performing truing using the truing device, first, a diamond grinding wheel 3 as a workpiece is attached to the spindle 14, and the first truing tool 13 is moved to a machining position together with the tool support 12 and the feed table 11. Then, the diamond grinding wheel 3 and the first truing tool 13 are independently rotated, and the outer peripheral surface, which is the working surface of the diamond grinding wheel 3, is ground into a perfect circle by the machining truing as described above. After performing this processing type truing, the first truing tool 13 is moved to the retracted position.
[0093]
Next, with the diamond grinding wheel 3 attached to the main shaft 14, the electrolytic dressing device 16 is moved to the processing position, and the electrode 17 is disposed at a predetermined interval between the diamond grinding wheel 3. Since the cathode of the DC power supply 18 has already been connected to the electrode 17, the anode of the DC power supply 18 is connected to the diamond grinding wheel 3 and the diamond grinding wheel 3 is rotated through the main shaft 14 as described above. Similarly, the outer peripheral surface of the metal bond of the diamond grinding wheel 3 is uniformly electrolytic dressed. After completion of this dressing, the DC power supply 18 is removed from the diamond grinding wheel 3 and the electrolytic dressing device 16 is moved to the retracted position.
[0094]
Next, the second truing tool is moved to the machining position together with the process support base and the feed table while the diamond grinding wheel 3 is still attached to the main shaft 14.
[0095]
Subsequently, the diamond grinding wheel 3 and the second truing tool, which are workpieces, are independently rotated, and the polishing truing is performed in the same manner as described above, and the tip of each diamond abrasive grain protruding from the outer peripheral surface of the metal bond. Polish the part and align the cutting edge height. After completion of this polishing type truing, the second truing tool is moved to the retracted position, and one truing stroke of the diamond grinding tool 3 is completed.
[0096]
According to the truing device of the embodiment of FIG. 16, the processing type truing, the electrolytic dressing, and the polishing type truing are sequentially performed in a state where the diamond grinding wheel 3 as a work is attached to the main shaft 14. The mounting error of the diamond grinding wheel 3 can be eliminated, so that the truing can be performed with higher accuracy and the above-described processing can be performed continuously, so that the work efficiency can be improved.
[0097]
In this embodiment, it is possible to perform truing of the cup-type diamond grinding wheel by supporting the main shaft in the vertical direction. Further, a mechanical dressing device may be used instead of the electrolytic dressing device 16.
[0098]
Other configurations and operations of this embodiment are the same as those of the embodiment shown in FIGS.
[0099]
Next, specific examples of the present invention will be described.
[0100]
Example 1:
Using the truing apparatus shown in FIG. 16, truing was performed by grinding the outer peripheral surface of a disk-shaped diamond grinding wheel 3 as a workpiece and shaping it into a perfect circle.
A diamond grinding wheel 3 made of metal bond 2 was used as a workpiece. This diamond grinding wheel 3 has a diameter = 124.5 mm and a thickness = 1.5 μm.
The main shaft 14 was supported by a hydrostatic air bearing as a hydrostatic bearing. The rotational accuracy of the main shaft 14 was 0.2 μm, and the rotational speed of the main shaft 14 was N = 1000 rpm during truing.
As the first truing tool 13, a cup-type metal bond diamond grindstone was used. As this diamond grindstone, a diamond abrasive grain size of about 200 to 400 # is good, and the diamond abrasive grain must protrude sufficiently from the metal bond. If the protruding amount of diamond abrasive grains is small, dressing is necessary. The rotation speed n of the first truing tool 13 was 3500 rpm.
[0101]
In the truing device used in the first embodiment, the main shaft 14 is supported by a static pressure air bearing, and the first truing tool 13 and the main shaft 14 are driven to rotate by independent rotary driving sources. It rotates with high accuracy (rotational accuracy of the main shaft 0.2 μm, rigidity 80 N / μm). If a hydrostatic oil bearing is used as the hydrostatic bearing, the rigidity can be further increased.
[0102]
A diamond grinding wheel 3 as a workpiece was attached to the main shaft 14 via a flange and a clamp. Since there is a fit tolerance between the main shaft 14 and the diamond grinding wheel 3, a rotational runout of several tens of μm is generally generated in the diamond grinding wheel 3. Even if the setting of the diamond grinding wheel 3 with respect to the main shaft 14 is devised, rotational runout of about 10 μm occurs.
[0103]
The first truing tool 13 was mounted on the tool support 12 so that the side runout was within 10 μm. Then, the diamond grinding wheel 3 is rotated through the main shaft 14 and the first truing tool 13 is rotated while the diamond grinding wheel 3 is brought into contact with the first truing tool 13 to move the feed table 11 in one direction. And truing under the following conditions.
[0104]
Truing conditions
・ Work Metal bond diamond grinding wheel
・ First truing tool SD200Q125M
・ Spindle speed N 1000rpm
・ Feeding table feed speed f 10.0mm / min
・ One-time cutting depth d 1.0μm
・ Grinding fluid Water-soluble grinding fluid
・ Grinding fluid flow rate 2.0 liters / min
[0105]
Truing was performed under the above truing conditions, and the rotational runout of the diamond grinding tool 3 was measured after truing. The rotational run-out was measured by using a differential transformer displacement meter, measuring the stylus against the outer peripheral surface (working surface) of the diamond grinding wheel 3 and recording it on a recorder.
[0106]
FIG. 7 is a graph showing the measurement results of rotational runout of a true diamond grinding wheel.
[0107]
In FIG. 7, A shows the case of truing by the so-called drop-out type truing method which is the prior art, B shows the case of truing with a commercially available truing device using a ball bearing as the bearing supporting the main shaft, and C shows the above FIG. 17 shows a case where the truing apparatus shown in FIG.
[0108]
FIG. 7A shows a case where a commercially available truing apparatus in which the main shaft is supported by a ball bearing is used, and a GC grindstone is used as a truing tool. The rotational run-out of the diamond grinding wheel trued by the conventional truing-out truing method is on the order of microns, and when the average abrasive grain size of the diamond grinding wheel becomes larger than 20 μm, the rotational run-out of the diamond grinding wheel abruptly increases. It tends to be large and it is difficult to suppress rotational runout.
[0109]
FIG. 7B shows a case where a commercially available truing apparatus in which the main shaft is supported by a ball bearing is used, and a diamond grindstone is used as a truing tool. This truing device had rigidity = 3 N / μm and rotational accuracy = 8 μm. Using this truing apparatus, a diamond grinding wheel was trued in the same manner as in the processing type truing method. As a result, as can be seen from FIG. 7B, the rotational runout of the diamond grinding wheel could not be reduced.
[0110]
On the other hand, as a result of truing the diamond grinding wheel by the processing type truing method according to Example 1, as shown in FIG. The rotational runout could be suppressed to 0.3 μm or less.
[0111]
8 is a 100 × SEM (scanning electron microscope) photograph of the outer peripheral surface of a diamond grinding wheel ground by the truing method according to the present invention, and FIG. 9 is a 2000 × SEM photograph. Please refer to Figs. 8 and 9 attached to the original application (Japanese Patent Application No. 193714) for the clear pictures of Figs.
[0112]
In the diamond grinding wheel trued by the truing method according to Example 1 described above, the surface of the metal bond and the tip of the diamond abrasive grains exist in the same plane, and as shown in FIGS. 8 and 9, the diamond abrasive grains There is no missing mark.
[0113]
Example 2:
The metal bond 2 of the diamond grinding wheel 3 that was trued in Example 1 was dressed by the electrolytic dressing method.
[0114]
As described above, in the diamond grinding wheel after truing, since the metal bond and the tip of the diamond abrasive grain exist in the same plane, when used as it is, the surface of the metal bond and the work material Contact with each other and normal grinding is not performed. For this reason, the dressing which protrudes the front-end | tip part of a diamond abrasive grain from the surface of a metal bond is required.
[0115]
In Example 2, an electrolytic dressing method was used as a dressing method. In the electrolytic dressing method here, an electrolytic dressing apparatus 16 shown in FIG. 16 was used.
[0116]
The electrode 17 was arranged with a gap g = 0.10 to 0.15 mm between the outer peripheral surface of the diamond grinding wheel 3 as a workpiece. The anode of the DC power source 18 was connected to the diamond grinding wheel 3 and the cathode was connected to the electrode 17. The grinding fluid 19 is passed between the diamond grinding wheel 3 and the electrode 17, and the diamond grinding wheel 3 and the electrode 17 are energized to rotate the diamond grinding wheel 3 and dress the metal bond 2 under the following electrolytic dressing conditions. did.
[0117]
Electrolytic dressing conditions
・ Work Metal bond diamond grinding wheel
・ Gap between workpiece and electrode g 0.13mm
・ Applied voltage 30V
・ Work speed 2000rpm
・ Grinding fluid Water-soluble grinding fluid
・ Grinding fluid flow rate 6.0 liter / min
・ Dressing time 1.0min
[0118]
As a result of performing dressing under the above electrolytic dressing conditions, the metal bond 2 could be uniformly removed on the surface to an average of 3 μm in the radial dimension, and the tip of the diamond abrasive grain 1 could be sufficiently projected. .
[0119]
Example 3:
After removing the surface of the metal bond 2 by the electrolytic dressing method and protruding the diamond abrasive grains 1, the tip of the diamond abrasive grains 1 was polished using a truing apparatus shown in FIG.
[0120]
As described above, the diamond grinding wheel 3 in which the metal bond 2 of the diamond grinding wheel 3 is removed and the tip of the diamond abrasive grain 1 is protruded is, for example, ductile mode grinding with a critical cutting depth of a brittle material. In addition, it cannot be used for applications in which the surface of the magnetic head facing the recording medium is ground to a surface roughness comparable to that of lapping. When used for these applications, it is necessary to polish the tip of the diamond abrasive grain 1 protruding from the metal bond 2 and to align the cutting edge height of the diamond abrasive grain 1.
[0121]
Therefore, the tip of the diamond abrasive grain 1 protruding from the surface of the metal bond 2 is trued by a polishing truing method so that the cutting edge height of the diamond abrasive grain 1 is made uniform. As the second truing tool, a cup type cast iron surface plate was attached and used. The diamond grinding wheel 3 is rotated by the main shaft 14 and a rotational drive source, and the outer surface of the diamond grinding wheel 3 is brought into contact with the upper surface of the second truing tool while the second truing tool is rotated by another rotational drive source. It was. Next, a small amount of cut feed was applied to the diamond grinding wheel 3, the feed table was fed at a predetermined feed speed, and truing was performed under the following truing conditions.
[0122]
Truing conditions
・ Work Metal bond diamond grinding wheel
・ Second truing tool Cast iron surface plate (FC20)
・ Rotation speed of second truing tool n 3500 rpm
・ Spindle speed N 1000rpm
・ Feeding table feed speed f 5.0mm / min
・ One-time cutting depth d 0.2μm
[0123]
Under the above truing conditions, the tip of the diamond abrasive grain 1 of the diamond grinding wheel 3 was trued by the polishing truing method, and then the cutting edge height of the diamond abrasive grain 1 was measured.
[0124]
FIG. 10 is a conceptual diagram of an apparatus for measuring the cutting edge height of abrasive grains of a grinding wheel, and FIG. 11 is an explanatory diagram of a method for evaluating measurement data obtained by the measuring apparatus.
[0125]
Here, the cutting edge height of the diamond abrasive grain 1 of the diamond grinding wheel 3 was measured using the abrasive grain cutting edge height measuring device shown in FIG. 10, and processed according to the measurement data evaluation method shown in FIG. . That is, the stylus displacement meter 26 of the abrasive cutting edge height measuring device shown in FIG. 10 is applied to the outer peripheral surface of the diamond grinding wheel 3 after the diamond abrasive grain 1 is polished, and the diamond grinding wheel 3 is moved at an extremely low speed. The two-dimensional profile of the outer peripheral surface of the diamond grinding wheel 3 was measured and recorded on the recorder 27.
[0126]
And about the obtained measurement data, as shown in FIG. 11, the reference | standard length L is taken and the front-end | tip part of the diamond abrasive grain which protrudes most among the diamond abrasive grains 1 contained in this reference | standard length L is taken. Was taken as a reference point P, a reference range t higher than the reference point P was taken, the number of tips of the diamond abrasive grains 1 falling within the reference range t was counted, and this was used as an evaluation method for truing accuracy.
[0127]
As a result, with regard to a metal bond diamond grinding wheel with diamond abrasive precision = 800, a GC grinding wheel was added to a commercially available truing device (using a ball bearing to support the spindle, rigidity = 3 N / μm, rotational accuracy = 8 μm) as a conventional truing method. And truing according to the truing method according to the present invention and the cases of truing according to Examples 1, 2, and 3 were evaluated by the evaluation method. The reference length L = 1 mm and the height reference range t = The number of tips of diamond abrasive grains contained in 0.5 μm, that is, the number of cutting edges, is four for diamond grinding wheels trued by the conventional truing method. Examples 1, 2 according to the truing method of the present invention The number of diamond grinding wheels 3 trued with 3 was 42. As is apparent from this measurement result, it can be seen that the diamond grinding wheel 3 trued by the truing method according to the present invention has the same cutting edge height of the diamond abrasive grains 1.
[0128]
FIG. 12 is an SEM photograph of the outer peripheral surface of a diamond grinding wheel which is a product trued by the truing method according to the present invention. For the clear picture of Fig. 12, please refer to Fig. 12 attached to the original application (Japanese Patent Application No. 193714).
[0129]
From FIG. 12, according to Example 3, the tip of diamond abrasive grain 1 protruding from the surface of metal bond 2 is polished with a cast iron surface plate, so that the cutting edge cross section of diamond abrasive grain 1 is flat. Moreover, it turns out that it is shape | molded smoothly and the cutting-edge height of many diamond abrasive grains 1 is arrange | equalized neatly.
[0130]
Example 4:
Using the diamond grinding wheel 3 truing by the truing method according to the present invention and the diamond grinding wheel truing by the conventional truing method, grooving was actually performed, and the surface roughness of the groove was measured. The work material is alumina titanium carbide.
[0131]
As a conventional truing method, a commercially available truing device (using a ball bearing to support the main shaft, rigidity = 3 N / μm, rotational accuracy = 8 μm) was used. A GC grindstone was attached to the truing apparatus as a truing tool. As the truing method according to the present invention, truing was performed according to Examples 1, 2, and 3.
[0132]
The processing conditions for the grooving with the diamond grinding wheel truing by the conventional truing method and the grooving with the diamond grinding wheel 3 truing by the truing method according to the present invention are as follows.
[0133]
Processing conditions
・ Grinding wheel Metal bond diamond grinding wheel
・ Work material Alumina titanium carbide
・ Processing machine spindle speed 4000rpm
・ Feeding speed of processing machine feed table 100mm / min
・ One-time cutting depth 2.0μm
[0134]
FIG. 13 is a graph showing the experimental results of the surface roughness of grinding using a diamond grinding wheel. In the experiment shown in FIG. 13, the processed surface roughness is obtained by measuring the roughness of the processed surface ground by the outer peripheral surface of the diamond grinding wheel. In FIG. 13, A is a diamond grinding wheel trued by a conventional truing method, and a GC grindstone is attached to a commercially available truing device (a ball bearing is used to support the spindle, rigidity = 3 N / μm, rotational accuracy = 8 μm). This shows the case of grinding with a truing diamond grinding wheel. In FIG. 13, B shows the case of grinding with the diamond grinding wheel trued according to Examples 1, 2, and 3 by the truing method according to the present invention.
[0135]
As can be seen from FIG. 13, the processed surface roughness when grinding with a diamond grinding wheel trued by the truing method according to the present invention is the same even with a rough diamond abrasive grain having an average abrasive grain diameter of 40 μm. It was possible to grind finish to a good processed surface with surface roughness = 0.2 μm Rmax. On the other hand, in the diamond grinding wheel trued by the conventional truing method, when the average abrasive grain size of the diamond abrasive grains exceeds 20 μm, the machined surface roughness deteriorates, and when the average abrasive grain size = 40 μm, the machined surface roughness. = 2.1 μm Rmax. From this experimental result, according to the diamond grinding wheel trued by the truing method according to the present invention, the processed surface roughness can be remarkably improved. This is the effect of aligning the cutting edge height of the diamond abrasive grains by the truing method according to the present invention.
[0136]
Example 5:
A cup-type diamond grinding wheel trued by the truing method according to the present invention is attached as a tool to a surface grinder, and the air bearing surface which is a surface facing the recording medium of the magnetic head for a magnetic disk shown in FIG. processed. As a result, it was possible to process to a processed surface roughness of 0.01 μm Rmax. Moreover, the processing step, which is the difference in processing amount of the magnetic head composite material, can be reduced from 0.05 μm in the case of lapping to 0.02 μm. Reducing the machining step in this way reduces the distance between the magnetic medium of the magnetic head and the magnetic disk surface, thereby improving the recording density. In other words, if the recording density is the same, the flying height of the magnetic head (the distance between the substrate 5 and the magnetic disk) can be increased by the amount that the processing step can be reduced, so that the risk of crash can be reduced. . Therefore, the reliability of the magnetic disk device can be improved.
[0137]
On the air bearing surface of the magnetic head finished by grinding, regular 10 nm-order grinding marks are formed in a certain direction. As a result, the frictional force when the magnetic head and the magnetic disk are in contact with each other is reduced, the risk of crash is reduced, and the reliability of the magnetic disk device is improved.
[0138]
From this result, it is understood that lapping has been conventionally performed in the finishing process of the magnetic head, but a magnetic head processed only by grinding can be manufactured.
[0139]
Further, lapping is currently used for finishing an optical system using an optical head or glass as a material, but it can be replaced with grinding in the same manner as the magnetic head described above.
[0140]
Next, various other embodiments of the present invention will be listed.
[0141]
In the present invention, the bond of diamond abrasive grains is not limited to a metal bond, and a resin-based bond may be used. When this resin-based bond is used, diamond abrasive grains are projected by a conventional mechanical dressing method instead of the electrolytic dressing method.
[0142]
In the present invention, the polishing of the tip of the diamond abrasive grains protruding from the surface of the bond is not limited to the case of performing only with a cast iron surface plate, and the diamond abrasive particles may be supplied onto the surface plate. Further, other polishing tools may be used instead of the cast iron surface plate.
[0143]
Furthermore, in the present invention, the first truing tool 13 and the second truing tool 24 are exchanged and attached to a single truing device, and the single truing device is attached to the first truing device and the second truing device. You may make it use for both.
[0144]
【The invention's effect】
In the invention described in claim 1 described above, in the diamond grinding wheel formed by a large number of diamond abrasive grains solidified by bonding and formed into a disk shape, the working surface of the grinding wheel is set so that the abrasive grains and the bond are flush with each other. Grinding into a perfect circle and dressing the ground bond uniformly to a predetermined depth so that the abrasive grains protrude from the surface of the dressed bond, and the tip of the projected abrasive grains is thermochemically Polishing and flat and smooth shaping, so that the cutting edge height of diamond abrasive grains can be precisely aligned, resulting in ultra-precise grinding in the ductile mode of brittle materials and recording media in magnetic heads There is an effect that can be applied to the grinding finish of the surface opposite to.
[0145]
In a second aspect of the present invention, in a diamond grinding wheel in which a large number of diamond abrasive grains are hardened with a bond to form a cup shape, the working surface of the grinding wheel is highly accurate so that the abrasive grains and the bond are flush with each other. The ground bond is ground to a flat surface and dressed uniformly to a predetermined depth to cause the abrasive grains to protrude from the surface of the dressed bond, and the tip of the protruded abrasive grains is thermochemically Since it is flattened and smoothed by polishing, the invention according to claim 2 is also applied to ultraprecision grinding in a ductile mode of a brittle material and grinding finishing of a surface facing a recording medium in a magnetic head. There is a possible effect.
[0146]
According to the third aspect of the present invention, a first truing device, a dressing device, and a second truing device are provided, and the first truing device is supported by a hydrostatic bearing and a large number of them. A main shaft that supports a diamond grinding wheel in which diamond abrasive grains are hardened with a bond as a workpiece, a rotational drive source of the main spindle, and a work surface of the diamond grinding wheel that is a workpiece, the diamond abrasive grains and the bond being substantially the same plane A first truing tool for grinding so as to have a rotational drive source of the first truing tool, and a cutting means for relatively sending the first truing tool and a diamond grinding wheel as a workpiece in a cutting direction. The dressing apparatus is configured to remove diamond abrasive grains by uniformly removing the ground surface of the ground bond to a predetermined depth. The second truing apparatus is configured to protrude from the surface of the bonded bond, and the second truing device is supported by a hydrostatic bearing and supports a dressed diamond grinding wheel as a workpiece, and a rotational drive source of the spindle. A second truing tool that aligns cutting edges by thermochemically polishing the tip of each diamond abrasive grain protruding from the surface of the dressed bond flatly and smoothly, and a rotational drive source of the second truing tool And a cutting means for relatively sending the second truing tool and the diamond grinding wheel as the workpiece in the cutting direction. In particular, both the first and second truing devices have a hydrostatic bearing as the main shaft. Are supported by each other and are rotated by independent rotational drive sources. Since it is possible to both rotational accuracy greatly improved, the effect of the truing method according to the present invention may be performed accurately.
[0147]
According to a fourth aspect of the present invention, the first truing tool and the second truing tool are selectively attached to a single truing device, and the single truing device is attached to the first truing device and the first truing device. Since it is also used as the truing device of No. 2, it is possible to reduce the equipment cost and to reduce the installation space of the device.
[0148]
According to invention of Claim 5, the position of the said spindle which supports the diamond grinding wheel which is a workpiece | work is fixed, The said 1st truing tool, the dressing apparatus, and the 2nd truing tool are each processing positions with respect to a workpiece | work. It is configured to be movable to the retracted position, so that the tip of diamond abrasive grains from the surface of the bond is processed truing that grinds the work surface of the diamond grinding wheel with the diamond grinding wheel attached to the main shaft. Polishing truing can be performed sequentially by polishing the leading edge of diamond abrasive grains and aligning the cutting edge height by polishing the tip of diamond abrasive grains. There is also an effect that the working efficiency can be improved.
[0149]
In the invention described in claim 6, a cup-type metal bond diamond grindstone is used as the first truing tool, and in the invention described in claim 7, a cup-type iron-based metal is used as the second truing tool. Further, in the invention according to claim 8, the dressing device includes an electrode arranged at a predetermined interval between the diamond grinding wheel and an anode as a diamond grinding wheel as a workpiece. Since the power source having the cathode and the cathode connected to the electrode and the rotational drive source of the diamond grinding wheel are provided, the truing method according to the present invention can be implemented more satisfactorily.
[Brief description of the drawings]
FIG. 1 shows one embodiment of a truing method according to the present invention, FIG. 1 (a) is a diagram showing a machining truing process of the outer peripheral surface of a diamond grinding wheel, and FIG. 1 (b) is a diagram of diamond abrasive grains. The figure which shows the dressing process of a bond, FIG.1 (c) is a figure which shows the grinding | polishing type | mold truing process of the diamond abrasive grain protruded from the bond.
FIG. 2 is a front view of a first truing device in the truing device of the present invention.
FIG. 3 is a side view of the central longitudinal section of FIG. 2;
FIG. 4 is a conceptual diagram of an electrolytic dressing device in the truing device of the present invention.
FIG. 5 is an enlarged view of a portion Q in FIG. 4;
FIG. 6 is a front view of a second truing device in the truing device of the present invention.
FIG. 7 is a graph showing measurement results of rotational runout of a truing diamond grinding wheel.
FIG. 8 is a 100 times SEM photograph of the outer peripheral surface of a diamond grinding wheel trued in a machining truing process in the truing method according to the present invention.
FIG. 9 is a 2000 times SEM photograph of the outer peripheral surface of a diamond grinding wheel trued in a machining truing process in the truing method according to the present invention.
FIG. 10 is a conceptual diagram of an apparatus for measuring the cutting edge height of abrasive grains of a grinding wheel.
11 is an explanatory diagram of an evaluation method for measurement data obtained by the measurement apparatus of FIG.
FIG. 12 is an SEM photograph of the outer peripheral surface of a diamond grinding wheel which is a product trued by the truing method according to the present invention.
FIG. 13 is a graph showing experimental results of roughness of a processed surface ground by a diamond grinding wheel.
FIG. 14 is an explanatory diagram of a truing method according to the present invention for a cup-type diamond grinding wheel.
FIG. 15 is an explanatory diagram of a truing method according to the present invention for a diamond grinding wheel with a shaft.
FIG. 16 is a front view showing another embodiment of the truing device of the present invention.
17A and 17B show the concept of truing of a diamond grinding wheel, FIG. 17A is a diagram showing the outer shape of a metal bond diamond grinding wheel before truing, and FIG. 17B is a metal bond diamond grinding wheel after truing. FIG.
FIG. 18 is a diagram showing a state of cutting edges of abrasive grains of a diamond grinding wheel before truing.
FIG. 19 is a schematic view of the surface state of a diamond grinding wheel trued by a conventional truing method.
FIG. 20 is a perspective view of a magnetic head.
FIG. 21 is an enlarged view of a portion S in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Diamond abrasive grain, 2 ... Metal bond, 3 ... Diamond grinding wheel, 4 ... Magnetic head, 8 ... Flange for diamond grinding wheel attachment, 9 ... The clamp, 10 ... 1st truing apparatus in a truing apparatus, 11 ... 1. Feeding table of first truing device, 12 ... tool support base, 13 ... first truing tool, 14 ... main shaft, 15 ... hydrostatic bearing of main shaft, 16 ... electrolytic dressing device in truing device, 17 ... electrolysis Electrodes of dressing device, 18 ... DC power source, 21 ... second truing device of truing device, 22 ... feeding table of second truing device, 23 ... same tool support, 24 ... second truing tool, 25 ... The main spindle, 30... Cup-type diamond grinding wheel, 31...

Claims (8)

In a diamond grinding wheel in which a large number of diamond abrasive grains are hardened with bonds to form a disk shape, the working surface of the grinding stone is ground in a perfect circle so that the abrasive grains and the bond are substantially flush with each other, and the grinding The processed bond is uniformly dressed to a predetermined depth so that the abrasive grains protrude from the surface of the dressed bond, and the tip of the protruded abrasive grains is thermochemically polished to form a flat and smooth shape. A diamond grinding wheel characterized by that. In a diamond grinding wheel in which a large number of diamond abrasive grains are hardened with a bond to form a cup shape, the work surface of the grinding wheel is ground to a high-precision plane so that the abrasive grains and the bond are flush with each other, and the grinding The processed bond is uniformly dressed to a predetermined depth so that the abrasive grains protrude from the surface of the dressed bond, and the tip of the protruded abrasive grains is thermochemically polished to form a flat and smooth shape. A diamond grinding wheel characterized by that. A first truing device, a dressing device, and a second truing device;
The first truing device is supported by a hydrostatic bearing and supports a diamond grinding wheel in which a large number of diamond abrasive grains are hardened with a bond as a workpiece, a rotational drive source of the spindle, and diamond grinding as the workpiece. A first truing tool for grinding the work surface of the grindstone so that the diamond abrasive grains and the bond are substantially flush with each other, a rotational drive source of the first truing tool, the first truing tool, and the workpiece It comprises a cutting means for sending a diamond grinding wheel relative to the cutting direction,
The dressing device is configured such that the surface of the ground bond is uniformly dressed to a predetermined depth so that the diamond abrasive grains can protrude from the surface of the dressed bond,
The second truing device is supported by a hydrostatic bearing and supports the dressed diamond grinding wheel as a work, a rotational drive source of the main shaft, and each of the surface of the dressed bond. A second truing tool that thermochemically polishes the tip of diamond abrasive grains flatly and smoothly to align the cutting edges, a rotational drive source of the second truing tool, the second truing tool, and the workpiece A truing device for a diamond grinding wheel characterized by comprising cutting means for relatively sending a diamond grinding wheel in the cutting direction. The first truing tool and the second truing tool are selectively attached to a single truing device, and the single truing device is used as both the first truing device and the second truing device. 4. A truing device for a diamond grinding wheel according to claim 3, wherein The position of the main shaft that supports the diamond grinding wheel as the workpiece is fixed, and the first truing tool, the dressing device, and the second truing tool can be moved to a machining position and a retracted position with respect to the workpiece, respectively. The truing device for a diamond grinding wheel according to claim 3 or 4, wherein the truing device is a diamond grinding wheel. The truing device for a diamond grinding wheel according to claim 3, 4 or 5, wherein a cup-type metal bond diamond grinding wheel is used as the first truing tool. 7. The diamond grinding tool truing apparatus according to claim 3, 4, 5, or 6, wherein a cup-type iron-based metal surface plate is used as the second truing tool. The dressing device includes an electrode disposed at a predetermined interval with the diamond grinding wheel, a power source in which an anode is connected to the diamond grinding wheel as the workpiece and a cathode is connected to the electrode, and the diamond grinding A truing device for a diamond grinding wheel according to claim 3, 4, 5, 6, or 7, characterized by comprising a grinding wheel rotational drive source.

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