JPH106182A - Machining method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform efficient machining by restricting the change of machining resistance. SOLUTION: In a machining control system, grinding resistance detected by a force sensor 5 mounted on a spindle 4 holding a work A is fedback to an arithmatic unit 7. A NC device 10 consists a feed power servo motor for a feed mechanism 9 for the work A, or the feed speed of a cutting tool 2 for the work A, in accordance with an operation signal calculated by the arithmetic 7 to restrict the change of machining resistance. To restrict even small change of the machining resistance, a servo controller 11 controls the servo motor to rotate a spindle 3 on which the tool 2 is mounted, or the rotating speed of the spindle 3 on which the tool 2 is mounted, in accordance with an operation signal calculated by the arithmetic unit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to precision machining, and more particularly, to a machining apparatus and a machining method for efficiently performing precision machining by suppressing a change in machining resistance that adversely affects machining accuracy.

[0002]

2. Description of the Related Art In order to prevent machining errors caused by quasi-static factors (for example, positioning errors, etc.) from decreasing, ultra-precision machining requires machining machines and tools designed with higher precision. used. However, this alone
In actual grinding, it is not possible to prevent a reduction in machining error due to other disturbances, for example, mechanical factors (such as deformation of a machine tool or a workpiece due to a grinding resistance acting between the workpiece and a tool). For example, even if a convex surface shape is created by precision machining, it is often found that a measurement error as shown in FIG. 6 is included when the surface shape is measured. By comparing FIG. 6 with FIG. 7, it can be seen that such a machining error increases with an increase in the grinding resistance due to an increase in the cutting feed amount of the tool over the outer periphery of the workpiece.

[0003] In order to reduce machining errors caused by such mechanical factors, the following two measures are generally taken.

As a first countermeasure, after a predetermined machining is completed, an inspection process for measuring the shape data of the workpiece using a shape measuring device or the like and a calculation based on the shape data obtained in the inspection process are further performed. By introducing a correction processing step of correcting the shape of a workpiece using processing data having a processing error as a correction value, a method of finally finishing the shape accuracy and surface roughness of the workpiece to a predetermined level. No.

[0005] As a second measure, the deformation of each part of the machine tool during operation, for example, the deformation (straightness change, etc.) due to the movement of a stage holding a tool or a workpiece is measured. Based on this data, there is a method of performing NC control on the relative feed motion of the tool with respect to the workpiece.

[0006]

However, when the above first measure is taken, extra time must be spent on the newly introduced measuring step and the correction processing step, and the processing efficiency is accordingly reduced. Is reduced.

On the other hand, when the above second measure is taken,
To fine-tune the position of the tool relative to the workpiece,
It is necessary to newly install an expensive fine movement mechanism or the like on the machine tool. That is, there is a problem that the cost of the processing system increases.

[0008] Therefore, it is an object of the present invention to provide a processing method capable of efficiently processing without changing the processing resistance. It is another object of the present invention to provide an inexpensive processing apparatus that realizes processing by such a processing method.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for cutting a tool into a workpiece by rotating the tool into at least one of the workpiece and the tool. A processing method for processing the workpiece in, a measuring step of sequentially measuring a processing resistance acting between the workpiece and the tool during processing, a target value of the given processing resistance, and the measurement Controlling the feed rate of a cutting feed motion in which the tool cuts into the workpiece in accordance with a difference between the workpiece and the working resistance measured between the tool and the workpiece measured in the step. Is provided.

[0010] Further, as an apparatus for realizing the present processing method,
A processing apparatus for processing the workpiece with the tool by cutting the tool into the workpiece while rotating at least one of the workpiece and the tool, wherein the workpiece and the Measuring means for sequentially measuring the working resistance acting between the tool, and a difference between a given target value of the working resistance and the working resistance measured between the workpiece and the tool measured by the measuring means. And a control device for controlling a feed speed of a cutting feed motion in which the tool cuts into the workpiece.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where an embodiment according to the present invention is applied to a grinding apparatus will be described below with reference to the accompanying drawings.

The grinding device used in the present embodiment is shown in FIG.
As shown in FIG. 2, a spindle 3 on which a tool (for example, a grinding wheel or the like) 2 is attached, similarly to a normal NC grinding machine.
Mechanism 8 for feeding the spindle 4 holding the workpiece A in the Y-axis direction, and a servo motor for rotating the spindle 3 on which the tool 2 is mounted.
(Not shown), a servo motor (not shown) for rotating the spindle 4 holding the workpiece A, an NC device 10 for controlling servo motors for feed power of the respective feed mechanisms 8 and 9, and the tool 2 are attached. And a servo drive device 11 for controlling each servo motor for rotating the spindle 3 holding the workpiece A and the spindle 4 holding the workpiece A. That is, the relative position of the tool 2 with respect to the workpiece A is numerically controlled by the NC device 10 so that the tool 2 moves along a predetermined tool path, and the workpiece A and the tool 2 are stably operated. The driving device 11 controls the rotation speed of the spindle 3 on which the tool 2 is mounted and the rotation speed of the spindle 4 holding the workpiece A so as to rotate.

By the way, usually, in the grinding process, the cutting feed speed of the tool 2 with respect to the workpiece A and the workpiece A
It is known that the grinding force acting between the workpiece A and the tool 2 increases with an increase in the rotation speed of the workpiece A (that is, the rotation speed of the spindle 4 holding the workpiece A) (see FIGS. 3 and 3). (See FIG. 4). Therefore, in addition to the above configuration, this grinding apparatus
Further, the grinding resistance acting between the workpiece A and the tool 2 is fed back so that the fluctuation of the grinding resistance acting between the workpiece A and the tool 2 is suppressed, and A configuration is provided for controlling the cutting feed speed and the rotation speed of the spindle 4 holding the workpiece A. That is, a force sensor 5 (for example, a strain gauge or the like) for measuring a grinding resistance acting between the workpiece A and the tool 2 is attached to the spindle 3 holding the workpiece A,
, The output signal a of the force sensor 5 is fed back as a main feedback signal. Then, the adjusting unit 12 amplifies the main feedback signal a fed back from the force sensor 5, the target value of the grinding resistance given as the reference input signal b, and the main feedback signal a amplified by the amplifier 6. Difference signal
(ab), so that the differential signal (ab) is given as an operation signal to the NC device 10 and the driving device 11 at the subsequent stage, respectively. Has become. In the present embodiment, the target value of the grinding resistance is set to a fixed value, but it is not always necessary to set the target value. For example, when grinding a workpiece A having a more complicated shape, it is more convenient to set the target value of the grinding resistance to a value that changes according to the curvature of the workpiece A. As a result, N
The C device 10 converts the given operation signal (ab) into an appropriate current, amplifies it appropriately, and then feeds the spindle 4 holding the workpiece A in the Y-axis direction by the feed mechanism 9. Supply to power servo motor. In other words, a current that reduces the deviation of the grinding resistance from the target value is supplied to the servomotor for the feed power of the feed mechanism 9. on the other hand,
The drive device 11 converts the given operation signal (ab) into an appropriate current, amplifies it appropriately, and then supplies it to a servomotor that rotates the spindle 4 holding the workpiece A. That is, a current that reduces the deviation of the grinding resistance from the target value is supplied to the servo motor that rotates the spindle 4 holding the workpiece A.

In this embodiment, the rotation speed of the spindle 4 holding the workpiece A and the tool 2
Is controlled together, but not necessarily,
There is no need to control both in this way. For example, there may be a case where it is better to control only the rotation speed of the spindle 4 holding the workpiece A, for example, when undulation and surface roughness are most important. In this case, it is more effective to control the rotation speed of the spindle 3 to which the tool 2 is attached, also. Further, if a current control minor loop for controlling a current value supplied to each servomotor is further provided, the stability and responsiveness of the system can be improved. Also,
The control of the rotation speed of each servomotor does not necessarily need to be performed by a current control method, and may be performed by, for example, a voltage control method.

By applying such a feedback control system, it is possible to suppress the fluctuation of the machining resistance which adversely affects the machining accuracy, and as a result, it is possible to obtain the effect of improving the machining accuracy. These effects are the result of the convex shape created by this grinding device (see FIG. 5).
And the measurement result of the convex shape created by the conventional grinding device (see FIG. 6) can be proved by comparison.

This concludes the description of the case where the embodiment according to the present invention is applied to a grinding apparatus. Incidentally, the embodiment of the present invention is a machine tool other than a grinding device (for example,
Even when the present invention is applied to a polishing apparatus or the like, the effect of improving the processing accuracy can be sufficiently obtained.

[0017]

According to the processing method and the processing apparatus according to the present invention, it is possible to suppress the fluctuation of the processing resistance which adversely affects the processing accuracy. Therefore, it is possible to create a good processed surface to the extent that it is not necessary to further perform the correction processing. Further, in order to realize the processing by the present processing method, a configuration not provided in the existing processing apparatus (for example, a fine movement mechanism as described in the section of the related art) is not required. Therefore, since the configuration of the existing processing apparatus can be used as it is, there is no need to make a new investment when creating the present processing apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a control system of a grinding device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the movement of a workpiece A and the movement of a tool 2;

FIG. 3 is a diagram showing a relationship between a cutting feed speed of a tool 2 with respect to a workpiece A and a grinding resistance.

FIG. 4 is a diagram showing a relationship between the number of rotations of a workpiece A and a grinding resistance.

FIG. 5 is a diagram showing a shape accuracy of a convex shape created by the grinding device according to the embodiment of the present invention.

FIG. 6 is a view showing the shape accuracy of a convex shape created by a conventional grinding device.

FIG. 7 is a diagram showing a variation in grinding resistance when a convex shape is created by a conventional grinding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Tool 3 ... Spindle 4 ... Spindle 5 ... Force sensor 6 ... Amplifier 7 ... Drive amplification circuit 8 ... Feeding mechanism 9 ... Feeding mechanism 10 ... NC device 11 ... Servo drive device 12 ... Adjustment part

Claims (5)

[Claims] 1. A processing apparatus for processing a workpiece with the tool by cutting the tool into the workpiece while rotating at least one of the workpiece and the tool. Measuring means for sequentially measuring a working resistance acting between the workpiece and the tool; and a working resistance acting between the workpiece and the tool measured by the given target value of the working resistance and the measuring means. And a control means for controlling a feed rate of a relative movement of the tool with respect to the workpiece according to a difference between the tool and the workpiece. 2. The processing apparatus according to claim 1, wherein the control means determines whether at least one of the workpiece and the tool has a feed rate of a relative movement of the tool relative to the workpiece. A processing apparatus, comprising: controlling a rotation speed of rotation. 3. The grinding apparatus according to claim 1, wherein the target value of the grinding resistance provided to the control means is a value determined according to a target shape of a surface of the workpiece. And grinding equipment. 4. The machining by the tool by cutting the tool into the workpiece and rotating the tool relative to the workpiece while rotating at least one of the workpiece and the tool. A processing method for processing a workpiece, wherein a measuring step of sequentially measuring a processing resistance acting between the workpiece and the tool during the processing, a target value of the provided processing resistance, and a measurement at the measurement step Controlling a feed rate of a relative movement of the tool with respect to the workpiece in accordance with a difference between the determined working resistance and the machining resistance acting between the tool. Method. 5. The machining method according to claim 4, wherein, in the control step, at least one of the workpiece and the tool together with a feed rate of a relative movement of the tool relative to the workpiece. A processing method characterized by controlling a rotation speed at which one rotates.