JPH07266202A - Grinding method - Google Patents

Abstract

PURPOSE:To provide a grinding method for grinding a work, of which one part is hardened by quenching, at a high roundness. CONSTITUTION:Rough grinding is firstly performed to a quenched part 33 of a work W. The quenched part 33, in which the residual stress is eliminated, is thereby returned to the original shape. Thereafter, contour grinding is started to finish the grinding of the whole of a work. Since the residual stress of the quenched part 33 is eliminated, and the contour grinding is performed after the quenched part 33 is returned to the original shape, deformation of the quenched part 33 after the contour grinding is eliminated, and the grinding at a high roundness can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding method for grinding the outer circumference of a work by rotating the work and the grindstone respectively and moving the grindstone relative to the work in the direction of the work rotation axis. The present invention relates to a grinding method for grinding a work that has been hardened with high circularity.

[0002]

2. Description of the Related Art At present, there is used a grinder which uses ultra-hard CBN abrasive grains and has a narrow width and a part of the outer circumference tapered to rotate at high speed to perform contouring grinding in one pass. . That is, in this type of grinder, for example, when grinding the workpiece W having the step portion 34 between the first cylindrical portion 31 and the second cylindrical portion 32 as shown in FIG.
While rotating the workpiece W and the workpiece W respectively, the workpiece W is relatively moved in the leftward direction in the drawing so that the first cylindrical portion 3
The outer periphery of No. 1 is ground (traverse grinding), the grindstone 16 is relatively moved in the workpiece diameter direction to grind the stepped portion 34 (plunge cut), and the workpiece W is further moved leftward in the drawing. Thus, the outer circumference of the second cylindrical portion 32 is ground. That is, the outer periphery of the work can be processed by one contouring grinding (one pass). Compared to the conventional grinders that can grind in one pass, the grinding time is longer than the conventional grinders that grind each cylindrical part multiple times, such as rough grinding, fine grinding, and fine grinding. Can be shortened.

[0003]

However, with a grinder capable of one-pass grinding, a part of the work as shown in FIG. 5 (33 indicated by hatching in the figure) is hardened. When W grinding is performed, a problem occurs that the grinding accuracy of the work is lowered. That is, there is a large residual stress in the quenched portion, and this residual stress acts as a force for suppressing the deformation of the work. When the periphery of the hardened portion 33 is ground, residual stress is removed, and this has an adverse effect such that the non-hardened portion ground before the hardened portion 33 has a large deflection. When the workpiece W is ground by one-time (one-pass) contouring grinding,
Machining is completed while the roundness of the work is reduced.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a grinding method capable of grinding a workpiece, a portion of which has been quenched, with a high roundness.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a grindstone 16 while rotating the work W and the grindstone 16 which are partially hardened.
In the grinding method in which the outer periphery of the work W is ground by relatively moving the work W in the direction of the rotation axis of the work W, the contouring grinding of the work W is started after the quenching portion 33 of the work W is ground. It is characterized by having done.

[0006]

With the above construction, in the grinding method of the present invention, the hardened portion 33 of the work W is first ground. As a result, the quenching portion 33 has its residual stress removed and returns to its original shape. After that, contouring grinding is started to complete grinding of the entire work. In this way, first the quenching part 3
Since the residual stress of No. 3 is removed and contouring grinding is performed after the hardened portion 33 has returned to its original shape, the hardened portion 33 is not deformed after contouring grinding, and grinding with high roundness is possible. Become.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a cylindrical grinding machine embodying a grinding method according to an embodiment of the present invention. In FIG.
A table 11 is guided and supported on the bed 10 so as to be horizontally movable. A headstock 13 and a tailstock 14 are arranged on the table 11 so as to face each other, and the headstock 13 is provided with a chuck 13a for gripping one end of a work W.
The tailstock 14 is provided with a center 14a for center-supporting the other end of the work W. Workpiece rotation axis is table 1
Headstock 13 and tailstock 1 so that they are parallel to the moving direction of 1
Both ends of the work W are supported by 4 and the work W is rotationally driven by the headstock 13. Then, the grindstone base 15 is guided and supported on the bed 10 in the horizontal direction orthogonal to the moving direction of the table 11,
A grindstone 16 is supported on the grindstone base 15 so as to be rotatable about an axis parallel to the moving direction of the table 11. The grindstone 16 is made of thin and super-hard CBN, and has a tailstock side taper and a headstock side gentle taper provided on the outer periphery thereof. It is rotatably driven at a very high speed via a belt and can perform grinding in a so-called one pass.

The table 11 is connected to the output shaft (not shown) of the servo motor 21, and the grindstone 15 is connected to the output shaft (not shown) of the servo motor 22.
The servo motors 21 and 22 are driven by drive circuits 23 and 2, respectively.
4 to the central processing unit 25, and an input device 26 and a memory 27 are connected to the central processing unit 25. A grinding program is stored in the memory 27, and the central processing unit 25 drives the servomotors 21 and 22 in accordance with the grinding program to move the table 11 and the grinding wheel head 15.

The work W has a first cylindrical portion 31 and a second cylindrical portion 3
A step portion 34 is provided between the first cylindrical portion 31 and the end portion 33 (hereinafter referred to as the quenching portion 33) of the first cylindrical portion 31, and is quenched. This work W is the first cylindrical portion 3
One side is gripped by the chuck 13a, and the second cylindrical portion 32 side is supported by the center 14a.

A rest device 40 shown in FIG. 2 is installed on the above-mentioned table 11 at a position corresponding to the quenching portion 33 of the first cylindrical portion 31, and the rest device 40 is mounted on the table 11.
A guide base 41 fixed on the top and a main body 42 fixed to the guide base 41 so as to be positionally adjustable in the workpiece diameter direction are provided. A first flange portion 43 and a second flange portion 44 are formed on the guide base 41 and the main body 42, respectively, and an adjusting screw shaft 45 is rotatably supported by the first flange portion 43, and one end of the adjusting screw shaft 45 is a second end. It is screwed onto the flange portion 44. By turning the adjusting screw shaft 45, the position of the main body 42 in the workpiece diameter direction is adjusted, and the bolt 4
The main body 42 is fixed to the guide base 41 by 6. Body 4
2, a cylinder device 47 is provided, and the cylinder device 47 is a piston rod 48 that moves forward and backward in the workpiece diameter direction.
A mounting member 49 is connected and fixed to the tip of the piston rod 48. An adjustment base 50 is fixed to the mounting member 49 so that the position thereof can be adjusted in the vertical direction, and a shoe 51 is fixed to the adjustment base 50 in a replaceable manner. Shoe 51
It is provided so as to be able to come into contact with the quenching portion 33 of the first cylindrical portion 31.

Next, the outer peripheral grinding of the work based on the above configuration will be described. The operator has a headstock 13 and a tailstock 14
When the work W is attached to and the grinding button (not shown) of the input device 26 is pressed, the grinding program stored in the memory 27 is read out and the grinding machine starts grinding according to the grinding program. The description will be continued below with reference to FIG. 3 showing a flow chart of the contents of the grinding program and FIG. 4 showing the relative movement of the grindstone 16 and the workpiece W.

First, in step 31, the grinder applies a drive signal to the grindstone drive motor 17 and the headstock 13 to work W.
And the grindstone 16 are rotated, and in step 32, the servomotor 21 is driven to move the grindstone 1 to the quenching portion 33 of the work W.
Position the table 11 so that 6 corresponds. Next, in step 33, the servomotor 22 is driven to move the grindstone base 15 forward to start the plastic cutting of the quenching portion 33, and this plastic cutting is performed in contouring s (see FIG. 4B) during contouring grinding described later. ) Continue until you leave. When the grinding is advanced to the machining allowance s position, the quenching portion 33 removes the residual stress and returns to its original shape. This completes the rough grinding of the hardened portion 33. Then step 3
In step 4, the whetstone base 15 is retracted.

Next, in step 35, the grinder moves the table 11 to the right to move the table 11 to the left end, that is, in FIG.
As shown in (B), the table 11 is positioned so that the grindstone 16 corresponds to the contouring grinding position. At this time, in step 36, the cylinder device 47 of the rest device 40 shown in FIG. 2 is driven to move the shoe 51 forward to bring it into contact with the roughened hardened portion 33. Since the forward end of the shoe 51 is set according to the diameter of the hardened portion 33 that has been roughly ground (that is, the diameter with the machining allowance s left), the work W is greatly moved toward the grindstone 16 by the forward movement of the shoe 51. It will not bend and be overcut. Further, since the shoe 51 is pressed against the hardened portion 33 whose surface is smoothed by rough grinding, wear does not proceed.

Here, the reason why the shoe 51 is pressed will be described. The work W has a high hardness portion and a low hardness portion regardless of the presence or absence of quenching. The grindstone 16 escapes in the hard portion, while the grindstone cuts into the work W side in the low hardness portion. Even if the depth of cut is set to a constant value, the actual depth of cut will change.
Grinding resistance of the workpiece 6 with respect to the work W changes, and due to the change of the grinding resistance, the work W escapes from the grindstone 16 side or returns to the grindstone 16 side. When the vibration of the work W due to the change in the grinding resistance and the natural vibration of the work W coincide with each other, self-excited vibration in which the vibration of the work W continues is generated. When this self-excited vibration occurs, the roundness of the work W decreases. Self-excited vibration tends to occur particularly in a work with low rigidity (thin). For this reason, in this embodiment, the quenching portion 33 is formed by advancing the shoe 51 and rough grinding as described above.
To prevent the circularity from decreasing due to self-excited vibration.

As shown in FIG. 4 (B), after the shoe 51 is brought into contact with the quenching portion 33, at step 37, the grindstone base 15 is pressed.
To advance the contouring grinding. That is, the grindstone base 15 is moved forward to grind the left end of the work W in the drawing to a finish diameter (shown by a chain line in the drawing), and the work W is moved leftward in the drawing to move the first cylindrical portion. The outer periphery of 31 is ground (traverse grinding). At this time, the machining allowance s of the quenching portion 33 that has already been roughly ground in step 34 is removed. As a result, since the hardened portion 33 that has regained its original shape is ground during the rough grinding, the hardened portion 33 can be ground with a high roundness. Further, in order to grind the remaining machining allowance s, the quenching portion 33
There is no step between the first cylindrical portion 31 and the first cylindrical portion 31. That is, when the grinding is performed without leaving the machining allowance s in the rough grinding, there is a step between the first cylindrical portion 31 and the quenching portion 33, but in this embodiment, the machining allowance s is left. Therefore, no step is generated. Then, in the step portion 34, the step portion 34 is ground (plunge cut) by relatively moving in the work diameter direction to the finishing diameter of the second cylindrical portion 32, and the work W
Is relatively moved to the left in the drawing to grind the outer periphery of the second cylindrical portion 32 (traverse grinding). afterwards,
In step 38, the shoe 51 and the grindstone base 15 are retracted, the rotation of the work W and the grindstone 16 is stopped, and the grinding of the work W is completed.

In this embodiment, the shoe 51 is pressed after the hardened portion 33 is roughly ground, that is, after the surface of the hardened portion 33 is smoothed to a certain degree.
1 does not wear. Further, since the work W is supported by the shoe 51, the work W having low rigidity can be ground with high roundness.

In the above embodiment, the step portion 3
The case of grinding the work W having No. 4 has been described as an example, but the present invention can also be applied to the case of grinding a straight-shaped work partially hardened. Also in this case, the hardened portion is first ground and then the entire contouring grinding is started. Further, in the above-described embodiment, when the hardened portion 33 is ground, an example in which only the plunge cut is performed is described. However, when the hardened portion is larger than the width of the grindstone, the traverse grinding may be performed after the plunge cut. Good. Furthermore, in the above-described embodiment, an example in which the shoe 51 is used for grinding has been given, but when the diameter of the work is sufficiently large and there is no problem in rigidity, grinding may be advanced without abutting the shoe. It is possible.

Further, in the above-described embodiment, the grinding is automatically advanced according to the grinding program, but the present invention can be used when the operator manually operates the grinder. Also in this case, the hardened portion is first roughly ground and then the entire contouring grinding is started.

[0019]

According to the present invention, since the hardened portion is roughly ground in advance to remove the residual stress in the hardened portion and the hardened portion is restored to its original shape, the contouring grinding is performed. It is possible to improve the grinding accuracy of.

[Brief description of drawings]

FIG. 1 is a plan view of a cylindrical grinding machine according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a rest device of the cylindrical grinder shown in FIG.

FIG. 3 is a flowchart showing the contents of a grinding program.

FIG. 4 is an explanatory diagram showing a grinding method according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a grinding method according to a conventional technique.

[Explanation of symbols]

 11 Table 13 Headstock 16 Whetstone 25 Central Processing Unit 27 Memory 33 Quenching Section 40 Rest Device 51 Shoe W Work

Front page continuation (72) Inventor Toshiaki Naya 1-1, Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Ryohei Mukai 1-1, Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Inventor Takamitsu Shibata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A grinding method for grinding the outer periphery of a work by rotating the work and the grindstone, which are partially hardened, respectively, and moving the grindstone relative to the work in the direction of the work rotation axis. In the above method, after the hardened portion of the work is ground, contouring grinding of the work is started.