JP4289191B2 - Grinding wheel oscillation method in internal grinding and internal grinding machine - Google Patents

Description

  The present invention relates to a grindstone oscillation method and an internal grinder that grind the inner surface of a cylindrical workpiece while oscillating a grindstone.

For example, a cylindrical workpiece such as a bearing ring of a rolling bearing is inserted on the inner diameter side, and the inner surface thereof is ground by an inner surface grinding machine provided with a rotating grindstone.
Oscillation grinding is performed by reciprocating (oscillating) a grindstone in the direction of its rotational axis during grinding in such internal grinding.

On the other hand, in order to manage the sizing accuracy of the workpiece, an in-process measurement may be performed in which an in-process gauge is inserted into the workpiece being ground to measure the workpiece dimensions.
In the case of small-diameter cylindrical workpieces, the grinding wheel and the in-process gauge probe cannot be brought into contact with the surface to be ground at the same time due to dimensional constraints. It is known that an in-process gauge is inserted into a workpiece and measured intermittently when the grindstone is moving backward. (For example, see Patent Document 1.)

However, in the in-process measurement synchronized with the oscillation in this way, it is necessary to set the oscillation process so that it is retracted at least from the measurement point of the in-process measurement when the grindstone is retracted. Become bigger. For this reason, since the actual processing time when the grindstone is in contact with the surface to be ground is reduced, there is a problem that the cutting speed is limited and the processing efficiency is lowered.
Japanese Patent Laid-Open No. 5-285808

  An object of the present invention is to provide a grinding wheel oscillation method and an internal grinding machine for internal grinding that improve the machining efficiency while ensuring the sizing accuracy of grinding.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, it attaches | subjects and demonstrates the code | symbol corresponding to the Example of this invention, but this invention is not limited to this.

  The invention of claim 1 includes a rough grinding step (S1) for grinding the inner surface of a cylindrical workpiece (W) while oscillating the grindstone (2), and the rough grinding step ( In-process for measuring the surface to be ground when the workpiece (W) is ground while oscillating in a stroke larger than S1) and the grindstone (2) is retracted from the surface to be ground of the workpiece (W). A grinding wheel oscillation method in internal grinding having a measuring step (S2).

  According to a second aspect of the present invention, in the grinding wheel oscillation method in the internal grinding according to the first aspect, in the rough grinding step (S1), the grinding stone (2) has a grinding portion over the entire stroke of the oscillation. A method for oscillating a grinding wheel in internal grinding, characterized by penetrating through a workpiece (W).

  According to a third aspect of the present invention, in the grinding wheel oscillation method in the internal grinding according to the first or second aspect, the oscillation cycle of the grinding wheel (2) is set to be more in-process than the rough grinding step (S1). It is a grinding wheel oscillation method in internal grinding characterized by shortening in the measurement step (S2).

  The invention according to claim 4 is a grindstone (2) inserted on the inner diameter side of a cylindrical workpiece (W), a rotation drive unit (4) for rotationally driving the grindstone (2), and a reciprocating drive for the grindstone. The oscillation drive unit (7), an in-process gauge (8) having a probe (8a) inserted on the inner diameter side of the workpiece (W), and any one of claims 1 to 3 It is an internal grinding machine (1) provided with the control part (9) which performs the grindstone oscillation method in the internal grinding of description.

According to the present invention, in rough grinding, by reducing the oscillation stroke, the actual processing time in which the grindstone is in contact with the surface to be ground can be lengthened and the grinding speed can be improved, thereby improving the processing efficiency. .
Further, in finish grinding, in which dimensional management is important, by performing in-process measurement, the sizing accuracy can be ensured, so that the machining efficiency can be improved while ensuring the sizing accuracy.

  The present invention aims to improve the machining efficiency while ensuring sizing accuracy, while performing a rough grinding step for performing oscillation grinding with a relatively small stroke, and performing oscillation grinding for a stroke larger than the rough grinding step. Solved by a grinding wheel oscillation method having an in-process measurement step for performing in-process measurement.

Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.
FIG. 1 is a diagram showing a configuration of an internal grinding machine used in Example 1 of a grinding wheel oscillation method to which the present invention is applied.
The internal grinding machine 1 includes a grindstone 2, a grindstone shaft 3, a grindstone spindle motor 4, an oscillation unit 5, a grindstone table 6, an oscillation motor section 7, an in-process gauge 8, and a control device 9. I have.

The grindstone 2 is formed in a substantially cylindrical shape, and grinds the inner surface of the cylindrical workpiece W with a grinding surface provided on the outer peripheral surface thereof.
The grindstone shaft 3 is a shaft portion on which the grindstone 2 is mounted.
The grindstone spindle motor 4 has a chuck portion (not shown) that holds the grindstone shaft 3 and rotates the grindstone 2 about its axis.
The oscillation unit 5 is a table provided with a grindstone spindle motor 4 and provided on the grindstone table 6, and reciprocates with the grindstone spindle motor 4 when oscillating.
The grindstone table 6 includes a linear guide (not shown) that linearly guides the oscillation unit 5. The direction of this linear motion guide is, for example, the axial direction of the grindstone spindle motor 4.
The oscillation motor unit 7 is a drive unit that reciprocates the oscillation unit 5 on the grindstone table 6, and includes a servo motor and an eccentric cam connected to an output shaft thereof. The servo motor has a function of changing the phase and speed of the eccentric cam in accordance with a position command from the control device 9, whereby the oscillation unit 5 has the position on the oscillation stroke and the speed of the oscillation. Be controlled.
The in-process gauge 8 is inserted on the inner diameter side of the workpiece W and includes a measuring element 8a that measures the dimension of the inner peripheral surface. The in-process gauge 8 is provided on the opposite side of the grindstone spindle motor 4 with the workpiece W interposed therebetween.
The control device 9 includes a central processing unit, and controls operations of the grindstone spindle motor 4, the oscillation motor unit 7, and the in-process gauge 8.

  The workpiece W is, for example, an inner ring of a deep groove ball bearing, and the inner surface grinding machine 1 grinds this inner circumferential surface. The workpiece W is arranged with its central axis parallel to the rotation axis of the spindle motor, and is held by a holding device (not shown).

Next, an internal grinding method using the internal grinding machine 1 will be described.
FIG. 2 is a graph showing the time-series displacement of the grindstone in the grindstone oscillation method of the first embodiment. The horizontal axis in FIG. 2 indicates time, and the vertical axis indicates the position of the grindstone tip.
The grinding wheel oscillation method according to the first embodiment includes a rough grinding step S1 for performing rough grinding, and an in-process measurement step S2 for performing finish grinding while performing in-process measurement.

In the rough grinding step S1, the oscillation stroke is set so that the grinding surface of the grindstone penetrates the workpiece W throughout the entire stroke.
FIG. 3 is a diagram showing a state of the workpiece W portion in the rough grinding step S1. Over the entire stroke of the oscillation in the rough grinding step S1, the tip 2a, which is the end on the in-process gauge 8 side of the grindstone 2, protrudes from the end surface on the in-process gauge side of the workpiece W, and the grindstone spindle of the grindstone 2 The rear end 2b, which is the end on the motor 4 side, protrudes from the end surface of the workpiece W on the grindstone spindle motor 4 side. In addition, a part of the inner peripheral surface of the work W is in contact with the outer peripheral surface of the grindstone 2 over the entire length in the axial direction.

  Further, since the servo motor of the oscillation motor unit 7 performs oscillation of a comparatively minute stroke, a forward and reverse position command is repeatedly given from the control device 9 and repeats a minute amount of forward and reverse rotation. A part of the phase of the eccentric cam is used, and the rotary motion of the servo motor is converted into a reciprocating motion. At this time, the speed of the servo motor is controlled so that the locus of the position of the time-series grindstone is substantially sinusoidal.

  The grinding conditions in the rough grinding step S1 are set in consideration of the fact that rough grinding, which is relatively less necessary to manage the dimensions of the workpiece W, is completed in a short period of time, and in particular, is set so as to increase the cutting speed. . And after completion | finish of rough grinding, it transfers to the in-process measurement step S2 mentioned later.

The in-process measurement step S2 performs finish grinding in a state where the oscillation process is larger than the rough grinding step S1 described above and the cycle is short (see FIG. 2).
The measuring element 8a of the in-process gauge 8 is driven in synchronization with the oscillation of the grindstone 2 based on a control command from the control device 9, and is inserted into the inner diameter side of the workpiece W when the grindstone 2 moves backward. In-process measurement of the measurement points described above is performed.
The grinding conditions in the in-process measurement step S2 are set in consideration of the sizing accuracy of the workpiece W and the finished roughness of the ground surface.

FIG. 4 is a diagram illustrating a state of the workpiece W unit during measurement in the in-process measurement step S2. The measurement point Wa, which is the object of measurement, is provided in the central portion in the axial direction on the inner peripheral surface of the workpiece W. The grindstone 2 is retracted until the tip 2a thereof is closer to the grindstone shaft 3 than the measurement point Wa, and the measuring element 8a of the in-process gauge 8 is in contact with the measurement point Wa to perform measurement.
Two measurement points Wa are provided symmetrically with respect to the center axis of the workpiece W, and the in-process gauge 8 detects the inner diameter of the workpiece W by measuring the distance between the two.

In order to perform high-speed oscillation, the servo motor of the oscillation motor unit 7 is given a position command in one direction from the control device 9, and continuously rotates at a substantially constant angular velocity in the same direction. As a result, the eccentric cam drives the grindstone 2 and the measuring element 8a of the in-process gauge 8 interlocked therewith by its original action.
Further, the switching from the rough grinding step S1 to the in-process measurement step S2 is controlled so that the oscillation of the sine wave-shaped grindstone smoothly transitions without a rapid change in speed.

As described above, according to the first embodiment, in the rough grinding step S1, the inner peripheral surface of the workpiece W is always ground by the grindstone 2 over its entire axial length, so that the cutting speed can be increased. Thereafter, in-process measurement is performed during finish grinding in the in-process measurement step S2, so that the sizing accuracy can be ensured. As a result, the cycle time required for processing can be improved while ensuring the sizing accuracy.
In the in-process measurement step S2, since the oscillation cycle is shortened, the measurement interval of the in-process measurement can be shortened and the measurement accuracy can be improved.

FIG. 5 is a diagram showing the configuration of an internal grinding machine used in Example 2 of the grinding wheel oscillation method.
The grinding wheel oscillation method of the second embodiment is similar to that of the first embodiment, but the configuration of the internal grinding machine used is partially different. Hereinafter, the same reference numerals are given to the same parts, the description thereof is omitted, and the differences will be described.

  The internal grinding machine 1A according to the second embodiment does not include the oscillation unit 5 unlike the internal grinding machine 1 according to the first embodiment. Instead, the grinding wheel table 6A that is linearly guided by a linear guide (not shown) is illustrated. The grinding wheel 2 is oscillated by being directly driven by a servo motor 10 connected through a ball screw that is not connected and moving the grinding wheel table 6A forward and backward by the servo motor 10.

Also in the second embodiment, the operation of the grindstone 2 is controlled to be the same as that shown in FIG.
First, in the rough grinding step S1, the servo motor 10 is repeatedly given a minute amount of forward and reverse position commands from the control device 9 in order to oscillate a relatively minute stroke. At this time, the locus of the rotation angle of the servo motor 10 is controlled to be a sine wave.
Next, in the in-process measurement step S2, the servo motor 10 is given a position command for increasing the amplitude of the sine wave and shortening the cycle from the control device 9. As a result, the stroke of oscillation of the grindstone 2 is increased, and in-process measurement is performed in the same manner as in the first embodiment.
According to the second embodiment, an effect similar to that of the first embodiment described above can be obtained by an internal grinding machine having a simple configuration.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
(1) In each of the above-described embodiments, the workpiece is an inner ring of a rolling bearing, but the workpiece is not limited to this and may be any other one as long as it is cylindrical or annular.
(2) In each of the above-described embodiments, the oscillation process and cycle are changed in two stages, but may be changed in three or more stages. Further, only the stroke may be changed without changing the cycle.
(3) The mechanism for oscillating the grindstone is not limited to the above-described embodiment, and other mechanisms may be used.

It is a figure which shows the structure of the internal grinder used for Example 1 of the grindstone oscillation method to which this invention is applied. It is a graph which shows the displacement of the time series grindstone in Example 1 of a grindstone oscillation method. It is a figure which shows the state of the workpiece | work part in the rough grinding step of Example 1 of a grindstone oscillation method. It is a figure which shows the state of the workpiece | work part in the in-process measurement step of Example 1 of a grindstone oscillation method. It is a figure which shows the structure of the internal grinder used for Example 2 of the grindstone oscillation method to which this invention is applied.

Explanation of symbols

1,1A Internal grinding machine 2 Grinding wheel 3 Grinding wheel shaft 4 Grinding wheel spindle motor 5 Oscillation unit 6, 6A Grinding wheel table 7 Oscillation motor part 8 In-process gauge 8a Measuring element 9 Control device 10 Servo motor W Workpiece

Claims (4)

A rough grinding step of grinding the inner surface of a cylindrical workpiece while oscillating a grindstone;
An in-process measurement step of grinding the workpiece while oscillating the grindstone with a stroke larger than the rough grinding step, and measuring the ground surface when the grindstone is retracted from the ground surface of the workpiece; A grinding wheel oscillation method in internal grinding. In the grinding wheel oscillation method in the internal grinding according to claim 1,
In the rough grinding step, the grinding wheel oscillates in the internal grinding, characterized in that the grinding part penetrates the workpiece throughout the entire stroke of the oscillation. In the grinding wheel oscillation method in the internal grinding according to claim 1 or 2,
A grinding wheel oscillation method in internal grinding characterized in that an oscillation cycle of the grinding wheel is shorter in the in-process measurement step than in the rough grinding step. A grindstone inserted on the inner diameter side of a cylindrical workpiece;
A rotational drive unit for rotationally driving the grindstone;
An oscillation drive unit for reciprocating the grinding wheel;
An in-process gauge having a probe inserted on the inner diameter side of the workpiece;
An internal grinding machine comprising: a control unit that executes the grinding wheel oscillation method in internal grinding according to any one of claims 1 to 3.

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