JPH06344254A - Grinding method and apparatus - Google Patents

Abstract

PURPOSE:To reduce the cycle time of a working process by performing working while a work shaft is rotated at a specified rotational frequency. CONSTITUTION:A holder 2 is located on the axis of a work shaft 3, driven in rotation on the basis of arbitrary setting of 100-500rpm, and adapted to removably hold a workpiece 1 on the forward end thereof. The line X-O' indicates the axis of the work shaft 3. A cup-type grinding wheel 4 is installed on the forward end of a spindle 13 and driven in rotation by the spindle 13 to perform spherical surface generating working for the workpiece 1. In this case, a rotary table 10 is turned on a rotary shaft 8, the opposite angle of the grinding wheel 4 to the workpiece 1 is changed, and the positional relationship of the above members is set by the relative adjustment of the forward and backward movement of the spindle 13, the opposite angle and the forward and the backward movement of the work shaft 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for forming curved surfaces of hard and brittle materials such as glass and ceramics.

[0002]

2. Description of the Related Art As an example of a production process of an optical element such as a lens by a conventional processing method, "Recess Burr High Speed Polishing" in "5.1 Lens Production Process" on page 197 of "Optical Element Processing Technology" issued by Japan Institute of Optical Industry In this example, three spherical surface processing steps are shown: spherical grinding, fine grinding and polishing. By the way, the precise grinding process in the conventional production process is
In order to shorten the cycle time, it is common to have two steps, a grinding step with a metal bond grindstone and a grinding step with a resin bond grindstone. Therefore, the conventional optical lens processing steps include four processing steps from spherical surface creation to polishing.

Hereinafter, in the conventional spherical grinding process,
A commonly used CG (curve generator) glass lens grinding method will be described with reference to FIGS. FIG. 5 shows an outline of the mechanism of a CG-based spherical grinding device. Known examples of such a spherical grinding device include, for example, Japanese Patent Publication No. 61-33665 and lens prism working technology (Chuo Kagaku). There is.

In FIG. 5, reference numeral 24 indicates a radius of curvature R.
Workpiece created in 0, collet chuck 25
It is held by the work axis. Reference numeral 26 denotes a work shaft main body, which has a mechanism (not shown) incorporated therein for performing the cutting a'while rotating the work 24.
Further, in order to adjust the wall thickness of the work 24, the work shaft main body 2
6 can be moved and adjusted in the a direction by a handle (not shown). Reference numeral 27 indicates a grindstone, and reference numeral 23 indicates a grindstone shaft. Further, a coolant (cooling medium) not shown is supplied between the work 24 and the grindstone 27.

According to the spherical grinding apparatus having the above-mentioned structure, as shown in FIGS. 5 and 6, when the processing diameter of the grindstone 27 that creates the workpiece 24 having the radius of curvature R0 is d, the grindstone shaft 23 has sin θ0 = d / Inclining by an angle θ0 corresponding to 2R0, and moving and adjusting the grindstone shaft 23 in a direction b perpendicular to the grindstone shaft by a handle (not shown) so that the machining diameter d coincides with the work shaft centerline at the point P. Thus, a spherical surface having a desired curvature radius O0P = R0 can be created.

At this time, the grindstone shaft 23 normally rotates at 4000 to 20000 rpm corresponding to the diameter of the grindstone so that the peripheral speed of the surface of the grindstone becomes 1000 to 2000 m / min.
The rotation of the work is set in the range of 3 to 20 rpm and the processing is performed.

[0007]

However, in the above-mentioned conventional grinding device and machining process, there are four processes to obtain a high-quality machined surface, so that the number of processes is large and the need for machining cost reduction. There is a drawback that it cannot handle. Even if a high-mesh superabrasive grain grindstone is applied in the spherical surface forming step, it is difficult to omit the subsequent step because the processing speed is reduced and the grindstone is clogged with the finer abrasive grains.

Therefore, the present invention was developed in view of the above-mentioned drawbacks of the prior art, and a grinding method capable of high-speed processing and at the same processing speed as that of the conventional processing method can be processed by a fine abrasive grain grindstone. And to provide a device.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a work holder that holds a work is supported by a rotatable work shaft, and a cup-shaped grinding wheel that is driven to rotate is held on the work surface. In the grinding method in which the curved surface generation processing is performed by contacting with 100 to 500 rpm
It is a method of performing machining while rotating the work shaft.

The workpiece is held and the number of rotations is 100 to 5
In a curved surface generating grinding device composed of a work holder rotatable at 00 rpm and a cup-shaped grinding wheel that is driven to rotate in opposition thereto, a means for dressing the cup-shaped grinding wheel by an electrolytic in-process dressing method. Is provided.

FIGS. 1 and 2 show the relationship between the rotational speed of a workpiece, the grinding speed, and the surface roughness (Rmax) of the machined surface when a glass lens as a workpiece is ground by the spherical grinding apparatus of the present invention. Is a graph showing (processing grindstone: metal bond diamond grindstone # 2000).

From the above FIGS. 1 and 2, the following is clear. That is, the rotation speed of the workpiece is 10 rp compared to
By increasing the speed from m to 500 rpm, the processing efficiency is increased four times in the same grindstone. In addition, there is no effect on the surface roughness of the machined surface by increasing the work rotation speed.

Further, as shown in FIG.
The cutting limit cutting speed sharply increases up to 00 rpm, and then gradually increases up to 500 rpm, and the improvement effect of the cutting limit cutting speed is small beyond that. Therefore, in the range of the work rotation speed of 100 to 500 rpm, the effect of improving the cutting speed is large, and it is most effective in reducing the number of processing steps.

[0014]

[Embodiment 1] FIG. 3 is a sectional view in which a part of the apparatus used in this embodiment is omitted. 11 is the base of the CG machine, this base 1
A slider 5 that can move forward and backward in the direction of the arrow E-E 'in the figure is provided at a predetermined position of 1. A work shaft 3 is attached to the slider 5, and a lens holder 2 is attached to the tip of the work shaft 3.

The lens holder 2 is located on the axis of the work shaft 3 and is configured to be rotationally driven under an arbitrary setting of 100 to 500 rpm. It is configured so that it can be held as much as possible. The X-O 'line indicated by the alternate long and short dash line in the figure indicates the axis of the work shaft 3.

On the other hand, 8 is a rotating shaft, which is erected at a predetermined position of the base 11 by a fixture 15 such as a bolt. In this embodiment, the rotary shaft 8 is formed in the shape of a fixed pin, and is fixed to the pin portion so that the housing 9 attached via the bearing 6 such as a ball bearing can rotate. There is. Reference numeral 7 indicates a mounting nut. The axis of the rotary shaft 8 is represented by the alternate long and short dash line Y-Y 'in the figure, and its standing position is set so as to intersect the axis X-O' of the work shaft at a right angle.

Reference numeral 10 denotes a turntable, one end of which is the housing 9 described above.
A spindle 13 is mounted via a slider 12 on the other end, that is, on the mounting table 10a. Similar to the slider 5 provided on the work shaft 3 side, the slider 12 is configured to be movable back and forth with respect to the mounting table 10a.

A cup-shaped grinding wheel 4 is attached to the tip of the spindle 13 and is driven to rotate by the spindle 13. The rotation center of the spindle 13 is the rotation axis Y-
The position is set so as to intersect with Y'perpendicularly, and the height is set so that the height coincides with the axis line X-O 'of the work shaft.

Therefore, when setting the spherical surface creation tool for the lens to be processed by the CG machine of this embodiment, the rotary table 10 is rotated around the rotary shaft 8 to create the spherical surface for the lens to be processed. The facing angle of the tool, that is, the angle θ described in FIG. 1 can be varied, and the positional relationship is set by mutual adjustment by the advancing / retreating of the spindle 13 and the facing angle θ and the advancing / retreating of the work shaft 3. It

When spherical surface forming processing is performed by the processing apparatus of this embodiment, since the work shaft 3 rotates at a high speed, it is possible to shorten the processing time of the conventional CG process. In addition, even if the mesh of the cup-shaped grindstone is raised compared to the conventional method, the amount of reduction in the processing speed is reduced, and processing with a finished surface equivalent to the level of the fine grinding step of the next step within the same processing cycle time as the conventional process. You can get a face.

[0021]

[Embodiment 2] FIG. 4 is a plan view of an essential part of an apparatus used in this embodiment. In the present embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the cup-shaped grinding wheel 22 can be electrolytically in-process dressed.

The machined surface of the cup-shaped grinding wheel 22 having conductivity is composed of a sintered alloy obtained by specially mixing abrasive grains such as diamond powder and metal powders such as Cu, Sn, and Fe and heat-treating them. . Further, the (+) pole of the power supply device 16 provided outside the device is electrically connected to the outer peripheral portion of the cup-shaped grinding wheel 22 via the brush 17.

The dressing electrode 18 connected to the (-) pole of the power supply unit 16 is formed in a shape similar to the machined surface of the cup-shaped grinding wheel 23, and the machined surface of the dressing electrode 18 and the cup-shaped grinding wheel 23 is formed. The dressing electrode holding member 19 is held by the dressing electrode holding member 19 such that the gap between the dressing electrode holding member 19 and the dressing electrode holding member 19 is 0.1 mm to 0.3 mm. Reference numeral 20 denotes a nozzle for supplying the weakly electric coolant 21 to the processing area by a coolant supply device (not shown).

In the processing method using the above-described processing apparatus, similarly to the first embodiment, the grinding wheel and the work are driven to perform the grinding processing, and at the same time, the weak electric coolant 21 is supplied from the nozzle 20 and the dressing is performed by the power supply device 16. A voltage is applied via the weakly electrically conductive coolant 21 interposed between the electrode 18 and the machined surface of the cup-shaped grinding wheel 22.

In this embodiment, even when a superabrasive grindstone of # several thousand or more (grinding stone number), which cannot be used due to clogging in the conventional grinding process, is used, the grinding stone is clogged. Without doing so, it is possible to perform spherical spherical grinding that is highly accurate and stable at high speed.

[0026]

As described above, according to the grinding method and apparatus according to the present invention, it is possible to perform processing at high speed in the spherical surface generating processing step of the optical element, and to process with the fine abrasive grain grindstone. Since it can be performed at the same processing speed as the conventional processing method, the cycle time of the optical element processing process is shortened,
Alternatively, the process can be shortened by eliminating the next fine grinding process.

[Brief description of drawings]

FIG. 1 is a graph showing the present invention.

FIG. 2 is a graph showing the present invention.

FIG. 3 is a cross-sectional view showing the first embodiment.

FIG. 4 is a main part plan view showing a second embodiment.

FIG. 5 is a plan view showing a conventional example.

FIG. 6 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 1 Workpiece 2 Lens Holder 3 Work Axis 4 Cup Type Grinding Wheel 5, 12 Slider 8 Rotation Axis 9 Housing 10 Rotation Base 11 Base 13 Spindle

Claims (2)

[Claims] 1. Grinding in which a work holder holding a work is supported by a rotatable work shaft, and a rotationally driven cup-type grinding wheel is brought into contact with the work surface held by the work holder to perform curved surface forming processing. In the processing method, 10
A grinding method characterized in that processing is performed while rotating the work shaft at 0 to 500 rpm. 2. The number of rotations is 100 to 500 while holding the work.
In a curved surface generating grinding device composed of a work holder rotatable at rpm and a cup-type grinding wheel that is driven to rotate in opposition thereto, a means for dressing the cup-type grinding wheel by an electrolytic in-process dressing method. A grinding machine characterized by being provided with.