JP2917085B2 - Grinding machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinder control device capable of changing processing conditions in accordance with the state of pre-processing of a workpiece.

[0002]

2. Description of the Related Art An internal grinding machine is one of devices for performing a grinding process. As shown in FIG. 5, the internal grinding machine rotates both the workpiece 51 and the grindstone 52 so that the inside of the workpiece 51 has a grindstone having a width smaller than the width of the workpiece 51 in the axial direction of the workpiece 51. The inner surface of the workpiece 51 is ground by making the traverse 52 move relatively and approaching.
In the case of performing the grinding with the inner surface grinding machine, it is necessary to machine a portion 53 of the workpiece 51 in which the run-out of the pre-processing remains, as shown in FIG. Note that the run-out refers to a deviation of the center in the pre-processing, distortion due to heat treatment, and the like.

[0003] If the inner surface of the workpiece has a run-out, the grinding wheel comes into contact with the workpiece intermittently, and the abrasion of the grinding wheel increases. Therefore, conventionally, until the run-out is removed,
Attempts have been made to reduce the cutting speed to reduce the wear of the grindstone. In this case, the power value for driving the grinding wheel axis,
In a grinding machine having a means for detecting the grinding force applied to the grindstone by the current value or the displacement of the shaft, etc., when it is detected that a part of the grindstone and the workpiece have contacted due to a change in the grinding force,
The cutting speed was switched to a low cutting speed for deflecting, the cutting was performed by a preset amount, and the cutting speed was increased again to continue the processing.

FIG. 6 is an explanatory diagram showing a relationship between a change in the grinding force (FIG. 6A) and a change in the cutting speed (FIG. 6B) in the grinding by the conventional internal grinding machine. FIG.
As shown in (b), conventionally, the cutting speed is increased in the area (1) before the grinding stone comes into contact with the workpiece, and thereafter,
In the region (2), the cutting speed (gap speed) is slightly reduced, and as shown in FIG. 6A, when it is detected that the grinding force has increased and the grinding wheel and a part of the workpiece have come into contact with each other. The cutting speed is switched to a low cutting speed for deflecting, and in the area (3), cutting is performed by a predetermined amount 54, and then rough grinding is performed in the area (4) and fine grinding is performed in the area (5). Had gone.

[0005]

However, conventionally, since it has not been possible to detect that the run-out of the pre-machining has been removed, it is necessary to set a safe amount in advance as the set amount 54. There is a problem that a useless processing time is generated depending on the state.

Further, since the grinding force increases as the run-out is removed, the detected grinding force is compared with the grinding force at the time when the grinding wheel contacts the entire surface of the workpiece to detect the time at which the run-out has been removed. However, when the width of the grindstone is narrower than the processing width of the workpiece, accurate detection cannot be performed for the following reasons. That is, as shown in FIG. 7, since the change in the grinding force due to the traverse position of the grindstone is larger than the change in the grinding force due to the removal of the run-out, not only is it difficult to detect a subtle change, but also Since there is a variation in the run-out in the axial direction of the workpiece, a simple comparison between the detected grinding force and the grinding force at the time when the entire surface comes into contact cannot accurately detect the time at which the run-out has been removed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a grinding machine control device capable of accurately detecting the point at which the run-out has been removed and enabling machining according to the state of pre-machining of a workpiece.

[0008]

According to the present invention, there is provided a control device for controlling a grinding machine in which a grindstone makes a periodic movement with respect to a workpiece, a grind force detecting means for detecting a value corresponding to a grind force applied to the grindstone. About the means and one cycle of the movement of the whetstone,
Integrating means for integrating the value detected by the grinding force detecting means, and run-out removal detecting means for detecting that the run-out of the workpiece has been removed by comparing the value integrated by the integrating means with a set value. And control means for controlling the operation of the grindstone based on the detection result of the shake removal detection means.

[0009]

In the control device of the grinding machine, the value corresponding to the grinding force applied to the grinding wheel is detected by the grinding force detecting means, and this value is integrated for one cycle of the movement of the grinding wheel by the integrating means. By comparing the value integrated by the integrating means with the set value, it is detected that the run-out of the workpiece has been removed. As described above, since the value corresponding to the grinding force is integrated with the set value for one cycle of the movement of the grindstone, the workpiece can be shaken without being affected by the grinding force fluctuating depending on the position of the grindstone. Can be detected. The control means controls the operation of the grindstone based on the detection result of the shake removal detection means.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a control device for a grinding machine according to the present invention. FIG. 1 is an explanatory view showing the configuration of a grinding machine according to one embodiment of the present invention.

The grinding machine includes a headstock table 1 and a grinding wheel table 2. The headstock table 1 can be moved back and forth along the axial direction X by a motor 3, and the grinding wheel table 2 is moved in the axial direction Z by a motor 4. It is provided to be able to move back and forth along. A cylindrical workpiece 5 is mounted on the headstock table 1, and the workpiece 5 is rotatably held by a support mechanism (not shown). On the other hand, a magnetic bearing type spindle 7 is attached to the grindstone table 2 via a spindle mount 6. This spindle 7
A grindstone 9 is attached to one end of the rotor shaft 8 and a circular thrust disk 10 is integrally formed near the center of the rotor shaft 8 in the longitudinal direction.

On the outer peripheral surface side of the rotor shaft 8, two sets of radial magnetic bearings are provided with the thrust disk 10 interposed therebetween. One set of radial magnetic bearings has four radial electromagnets 12 and a radial position sensor 13. Of the four radial electromagnets 12, two opposing radial electromagnets 12 are configured to operate as a pair, and the four radial position sensors 13 similarly operate as a pair of two opposing radial position sensors 13. It is configured to be.

A motor 14 for rotating the rotor shaft 8 is provided on the outer peripheral surface side of the rotor shaft 8.
As shown in FIG. 2, the two pairs of radial electromagnets 12 and the radial direction position sensor 13 are arranged on the cylinder at 90 ° offset from each other about the rotor axis.

On the other hand, around the thrust disk 10,
One set of axial magnetic bearings is provided. The axial magnetic bearing has two donut-shaped axial electromagnets 15 and an axial direction position sensor 16. The two axial electromagnets 15 are arranged so as to face each other via the thrust disk 10, while the axial direction position sensor 16 is arranged on the rotor shaft end face side.

The radial position sensor 13 and the axial position sensor 16 are configured to output their respective sensor detection values to a control unit 20 as a control device. The control unit 20 controls the motor driver 21 for driving the motor 14, the servo motor driver 22 for driving the motor 3 and the motor 4, the electromagnet driver 23 for driving the radial electromagnet 12 and the axial electromagnet 15, and the servo motor driver 22. And a grinding machine NC device 24.

The control section 20 is provided with a position detection circuit 25 and a processing circuit 26. Position detection circuit 25
The detection values of the sensors 13 and 16 are input to the control unit 26. Based on the detection values, the radial floating position and the axial floating position at both ends of the rotor shaft are obtained and output to the processing circuit 26. The processing circuit 26 stores the radial target positions at both ends of the rotor shaft, compares the target position with the radial floating position at one end of the rotor shaft 8, amplifies the comparison deviation, and amplifies the electromagnet driver. 23. The electromagnet driver 23 outputs an exciting current corresponding to the comparison deviation to the radial electromagnet 12. At the same time, the processing circuit 2
In 6, the same processing is performed for the radial floating position at the other end of the rotor shaft.

The processing circuit 26 stores a target position of the rotor shaft 8 in the axial direction, compares the target position with the axial floating position, amplifies the comparison deviation, and amplifies the deviation to the electromagnet driver 23. The electromagnet driver 23 outputs the exciting current corresponding to the comparison deviation to the axial electromagnet 15.

In this manner, the radial electromagnet 12 and the axial electromagnet 15 are excited, and the rotor shaft 8 is supported at a predetermined position in a non-contact manner. Further, the control unit 20 is provided with a grinding force detection circuit 28. The grinding force detection circuit 28 detects the grinding force from the exciting current value of the electromagnet by utilizing that the change in the excitation current by the electromagnet driver 23 corresponds to the change in the grinding force applied to the grindstone 9. .

The control unit 20 includes a shake amount detection unit 30
Is provided. The run-out amount detector 30 detects the change in the grinding force detected by the grinding force detection circuit 28,
Detection circuit 31 for detecting that the object has come into contact with the workpiece 5
An integration circuit 32 for integrating the grinding force detected by the grinding force detection circuit 28 for one reciprocation of the traverse movement of the grinding wheel 9; and a runout removal detecting means for comparing the integrated value of the integration circuit 32 with a set value. And a comparison circuit 33. When the contact detection circuit 31 detects a contact, it sends a speed switching signal 34 to the grinding machine NC device 24. The grinding machine NC unit 24 sends a position signal 35 indicating that the grinding wheel 9 has reached the retreating end to the integration circuit 32, and the integration circuit 32 is reset by the position signal 35. Further, the integration circuit 32 is also reset by a reset signal 36 output simultaneously with the speed switching signal 34 from the contact detection circuit 31. When the integrated value of the integrating circuit 32 exceeds the set value, the comparing circuit 33 sends a speed switching signal 37 to the grinding machine NC unit 24 assuming that the grinding for the runout amount has been completed. The grinding machine NC device 24 switches the cutting speed according to the speed switching signals 34 and 37 from the runout amount detector 30.

Next, an outline of the operation of the control unit 20 in the present embodiment will be described with reference to FIG. FIG. 3A shows a change in the grinding force before the removal of the runout, and FIG. 3B shows a change in the grinding force after the removal of the runout. As shown in these figures, when the run-out is removed, the grinding force increases. Further, the grinding force periodically varies depending on the traverse position of the grindstone 9. Here, the times when the grindstone 9 reaches the retreat end are defined as t ₁ , t ₂ ,. As shown in FIG.
Since the grinding force fluctuates according to the traverse position even after the run-out is removed, the point at which the run-out has been removed cannot be accurately detected simply by comparing the detected grinding force with the set value.

Therefore, in this embodiment, the grinding force is integrated for one cycle of the traverse movement of the grindstone 9 and this integrated value (shaded portion in the figure) is compared with a set value.
It detects that the shake has been removed. Thereby, the time point at which the run-out has been removed can be accurately detected without being affected by the grinding force that varies depending on the position of the grindstone 9.

Next, the operation of the control unit 20 in this embodiment will be described with reference to the flowchart of FIG. The control unit 20 first sets a set value for contact detection and a set value for shake amount detection (step 101).
These settings are, for example, once for one type of product,
It is determined by actually processing a workpiece and measuring.

Thereafter, the rotor shaft 8 is magnetically levitated, rotated by the motor 14, and
4. The grindstone table 2 is moved back and forth in the axial direction Y by the servo motor driver 22 and the motor 4.
In addition, the grinding machine NC device 24 and the servo motor driver 22
The motor 3 moves the headstock table 1 along the axial direction X at a predetermined cutting speed (gap speed).

Next, the process waits until the contact detection circuit 31 detects that the grindstone 9 has contacted the work 5 (step 102). When the contact is detected (step 102;
Y), a speed switching signal 34 is sent from the contact detection circuit 31 to the grinding machine NC device 24 (step 103). In response to the speed switching signal 34, the grinding machine NC unit 24
Switches the cutting speed to a predetermined swing-out speed. This run-out speed is a slow cutting speed in the area (3) in FIG. Speed switching signal 3
4 and the integration circuit 3 by the reset signal
2 is reset (step 104).

Next, the integration circuit 32 integrates the grinding force detected by the grinding force detection circuit 28, and the comparison circuit 33 determines whether or not the runout amount has been detected, that is, the integrated value exceeds the runout amount set value. It is determined whether or not it has been performed (step 105). If not exceeded (Step 105; N)
Determines whether or not the grinding machine NC device 24 detects that the grindstone 9 has reached the retreat end (step 10).
6). When it is not detected that the retreat end has been reached (Step 106; N), the integration of the grinding force and the determination as to whether or not the runout amount is detected (Step 105) are continued. When it is detected that the retreat end has been reached (Step 106; Y), the integration circuit 32 is reset (Step 104).

On the other hand, when the integrated value exceeds the set value of the run-out amount and the run-out amount is detected (step 105; Y), the comparison circuit 33 sends the speed switching signal 37 to the grinding machine NC unit 24.
(Step 107), and the shake amount detection unit 30 ends the operation. In response to the speed switching signal 37, the grinding machine NC device 24 switches the cutting speed from the run-out speed to the coarse grinding speed (the speed in the area (4) in FIG. 6) to continue the processing. Thereafter, the grinding machine NC device 24 switches the cutting speed to the fine grinding speed (the speed in the region (5) in FIG. 6), finishes the grinding by a predetermined amount, and ends the processing.

As described above, according to the present embodiment, the grinding force is integrated for one cycle of the traverse movement of the grinding wheel 9 and the integrated value is compared with the set value to confirm that the run-out has been eliminated. I try to detect. Therefore,
It is possible to accurately detect the point at which the run-out has been removed without being affected by the grinding force that fluctuates depending on the position of the grindstone 9, and to prevent unnecessary wear of the grindstone even when an abnormal workpiece is mixed. it can. Further, since the profile of the optimum cutting speed can be set according to the state of the pre-processing of the workpiece, the processing time can be reduced.

The present invention is not limited to the above embodiment,
For example, when the value of the grinding force is detected, the value is not limited to the value detected from the exciting current of the magnetic bearing that supports the rotor shaft 8 as in the embodiment. For example, the rotor shaft 8 is supported by a ball bearing, and The grinding force may be detected by disposing a load cell or the like. Further, the grinding force may be detected from a current value or a power value in the motor 14 for rotating the rotor shaft 8.

When it is detected that the run-out has been removed, an average value of the grinding force is obtained from an integrated value of the grinding force for one cycle of the traverse movement of the grindstone 9, and this average value and a predetermined set value are calculated. Alternatively, it may be detected that the shake has been removed. In addition, the present invention is not limited to the internal grinding machine, the grinding wheel width is narrower than the processing width of the workpiece, the grinding wheel also performs a periodic motion through the workpiece, such as a surface grinding or a cylindrical outer peripheral grinding machine. Can be applied.

[0030]

As described above, according to the present invention, the value corresponding to the grinding force of the grindstone is integrated for one cycle of the movement of the grindstone, and the integrated value is compared with the set value to thereby improve the machining efficiency. As we have detected that the runout of the object has been removed, it is possible to accurately detect the point at which the runout is removed without being affected by the grinding force that fluctuates depending on the position of the grinding wheel,
There is an effect that machining according to the state of pre-machining of the workpiece becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a grinding machine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of a radial electromagnet and a radial direction position sensor in the grinding machine of FIG. 1;

FIG. 3 is an explanatory diagram for explaining an outline of an operation of one embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 5 is an explanatory view showing a workpiece and a grindstone in an internal grinding machine.

FIG. 6 is an explanatory diagram showing a relationship between a change in a grinding force and a change in a cutting speed in a grinding process using a conventional internal grinding machine.

FIG. 7 is a characteristic diagram showing a change in grinding force in grinding by a conventional internal grinding machine.

[Explanation of symbols]

 5 Workpiece 8 Rotor shaft 9 Grinding stone 12 Radial electromagnet 15 Axial electromagnet 20 Control unit 23 Electromagnet driver 24 Grinding machine NC device 28 Grinding force detection circuit 30 Runout amount detection unit 31 Contact detection circuit 32 Integration circuit 33 Comparison circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-75855 (JP, A) JP-A-4-189447 (JP, A) JP-A-4-135143 (JP, A) JP-A-5-135 138499 (JP, A) JP 60-20146 (JP, B2) JP 2-16611 (JP, B2) (58) Fields studied (Int. Cl. ⁶ , DB name) B24B 49/16 B23Q 15 / 12 B23Q 15/013 B24B 49/10 B23Q 17/09

Claims (1)

(57) [Claims] 1. A control device for controlling a grinding machine in which a grindstone performs a periodic movement with respect to a workpiece, a grinding force detecting means for detecting a value corresponding to a grinding force applied to the grindstone, Integrating means for integrating the value detected by the grinding force detecting means for the period, and comparing the value integrated by the integrating means with a set value, thereby detecting that the run-out of the workpiece has been removed. A control device for a grinding machine, comprising: runout removal detecting means; and control means for controlling the operation of the grindstone based on a detection result of the runout removal detecting means.