JP2001038586A - Grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a trembling of a grinding processing surface by de- energizing a grinding wheel motor and finish-grinding by maintaining a motive portion from the grinding wheel motor to the grinding wheel in the state that the grinding wheel is rotated by a rotation force due to inertia. SOLUTION: After rough shaving, an X axis servo motor 12 is changed to a speed corresponding to a speed at which a feeding of a grinding wheel 6 becomes a finish feeding. At the same time, a numerical control device 13 controls a grinding wheel motor driving part 14 to de-energize a grinding wheel motor 3. So, the grinding wheel rotates by an inertia. A trembling mark is removed at the time of finish grinding and spark out even if the trembling mark caused by a trembling vibration based on an electromagnetic vibration is generated on a work W at the time of rough grinding by not energizing the grinding wheel motor 3 during finish grinding step. Even in the case where there is a condition that the trembling mark caused by the trembling vibration based on the electromagnetic vibration is generated by energizing the grinding wheel motor 3 at the time of finish grinding, since the grinding wheel motor 3 is de-energized, the trembling vibration is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding method and, more particularly, to a grinding method for grinding an outer periphery of a workpiece with a grindstone.

[0002]

2. Description of the Related Art Conventionally, chattering vibrations are generated in a grinding action portion due to vibrations on a grinding wheel side, and chattering marks are sometimes generated on a grinding finish surface.

[0003] Various cylindrical grinding methods have been proposed which employ such a method for preventing chatter vibration.

For example, Japanese Unexamined Patent Publication No. 5-69279 proposes a grinding wheel abnormal vibration monitoring device having a mechanism for changing the grinding wheel rotation speed when the frequency of chatter vibration caused by resonance coincides with an integer multiple of the grinding wheel rotation speed.

Japanese Patent Laid-Open Publication No. Hei 6-246601 discloses that in the case of traverse cutting, the occurrence of chatter marks is prevented by abutting a shoe on a portion ground with a grindstone.

In Japanese Patent Application Laid-Open No. 8-174379, vibration of a working machine tool is measured by a vibration detector and a frequency analyzer, the measured data is taken into data processing means, and this data is set in advance. The chatter vibration is detected by comparing it with a certain chatter vibration determination criterion, and when chatter vibration is occurring, the data processing means instructs the control device to change the operating condition to change the operating condition. After that, a chattering vibration suppressing method in which the vibration measurement and the change of the operating condition are repeated is described.
As a specific machine tool, a roll grinder is mentioned.

[0007]

The present invention is a further development of the above-mentioned prior art.

An object of the present invention is to provide a grinding method which prevents chattering of a ground surface due to electromagnetic vibration of a grinding wheel motor.

[0009]

Means for Solving the Problems A first invention according to the present application is a grinding method for grinding a workpiece using a grindstone,
A first step of energizing the grindstone motor to rotate the grindstone motor and sending the grindstone and the workpiece close to each other while rotating the workpiece, and rotating the grindstone motor and the workpiece in the same manner as the first step. A second step of rough-feeding and rough-grinding the workpiece while performing the finish-feeding by rotating the workpiece following the second step to finish-grind the whole or part during the finish-grinding A step of deactivating the grindstone motor to finish grind the grindstone continuously in a state where the grindstone is rotated by inertia of a moving part from the grindstone motor to the grindstone. It is.

[0010] A second invention according to the present application is that, when the grinding wheel motor is deactivated in the middle of the third step, the grinding wheel motor is rotated while the grinding wheel motor is deactivated following the third step. 2. The grinding method according to claim 1, further comprising a step of rotating the workpiece and sparking out without giving a cut feed.

A third invention according to the present application is the grinding method according to the first or second invention, wherein the grinding step is a traverse cut.

A fourth invention according to the present application is the grinding method according to the first or second invention, wherein the grinding step is a plunge cut.

The fifth invention according to the present application is directed to a case where the wheel motor is deenergized from the beginning of the third step.
In the spark-out process following the process
The grinding method according to the first invention, characterized in that spark-out is performed while maintaining the deenergized state of the grinding wheel motor in the step (1).

According to a sixth aspect of the present invention, in the grinding method according to the first aspect, the grinding wheel motor is energized in a state where the grinding wheel is separated from the workpiece after the third step is completed. Is the way.

According to a seventh aspect of the present invention, in the second or fifth aspect, the grinding wheel motor is energized in a state where the grinding wheel is separated from the workpiece after the spark-out is completed. It is a grinding method.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.

In this specification, energizing the grindstone motor means supplying power to a grindstone motor to which no power is supplied, and maintaining a state in which the power is supplied.
The deenergization of the grinding wheel motor means stopping the supply of power to the grinding wheel motor to which the power is being supplied, and maintaining the stopped state of the supply of power.

(Embodiment 1) A grinding machine used for carrying out the present grinding method includes a cam grinding machine, a cylindrical grinding machine (including a crank journal grinding machine) for performing plunge cut or traverse cut, and a plunge cut. It is a crank pin grinder, a universal grinder, or the like, and the cutting feed is performed by numerical control. X or Z for one or two of the wheel heads
Each type is driven in the respective directions to fix the table to the bed. The workpiece to which the present invention is applied preferably has a cylindrical shape, a cam shape, a conical shape, or a truncated conical shape, but all objects are applicable as long as they do not contradict the spirit of the present invention.

FIG. 1 shows a cylindrical grinder, and FIG. 2 shows a crankpin grinder for grinding a crankpin.

On the machine base 1, a grindstone base 2 is movably movable in the X direction.
Is provided, and a grindstone motor 3 is mounted on the grindstone table 2. A belt device 5 is provided between the grindstone motor 3 and the grindstone shaft 4. Omit this belt device,
A so-called built-in motor may be employed as the grindstone motor. A cylindrical grindstone (hereinafter sometimes simply referred to as a grindstone) 6 is attached to a grindstone shaft 4 rotatably supported by a bearing (not shown) on the grindstone stand 2.

On the machine base 1, there is provided a table 7 which is moved in the Z direction. On the table 7, a workpiece head 9 supporting and driving the workpiece W and a tailstock 11 simply supporting the workpiece W are provided.

The wheel head 2 is moved back and forth by an X-axis servomotor 12 connected to a screw feeder in the X-axis direction. The grinding wheel motor 3 is turned on and off under the control of the drive unit 14 from the numerical controller 13. The X-axis servo motor 12 is controlled by a numerical controller 13.

In the above, in the cylindrical grinding machine, the table 7 reciprocates in the traverse range. In the crank pin grinding machine, the table 7 can be indexed and moved to each crank pin position of the workpiece W.

FIGS. 3 and 4 show the tool paths of the grinding machines of FIGS. 1 and 2. FIG. In FIG. 3, the grinding process is a traverse cut. In FIG. 4, the grinding process is a plunge cut.

FIG. 5 shows a time chart in FIGS. At time t0, the workpiece head 9 and the grindstone motor 3 are urged as shown in FIGS. Whetstone 6
Becomes the rotation speed of FIG. 5C by the drive of the grindstone motor 3 stopped at the time t0. At time t1, the X-axis servo motor 12 is urged in rapid traverse as shown in FIG. 5 (d), and the grindstone 6 is rotated as shown in FIG. 5 (d) to (e).
Is fast-forwarded toward the workpiece W. Then, at time t2, the grindstone 6 becomes a position close to the workpiece W.

In the case of traverse cut and plunge cut as shown in FIGS. 5E to 5F, the X-axis servo motor 12 is decelerated so as to roughly feed the grinding wheel base 2. However, the traverse cut and the plunge cut have different infeed rates.

In the case of the traverse cut at the same time as FIG. 5 (f), the X-axis servomotor 12 is stopped as shown in FIG. 3 (a), and the workpiece is cut as shown in FIG. 3 (a) to (b). W
The length table 7 to be machined moves leftward, and when the leftward moving process is completed, the X-axis is cut so that the grindstone 6 is roughly fed toward the workpiece W as shown in FIGS. 3 (b) to 3 (c). Servo motor 1
2 is energized. Then, in FIG. 3C, the X-axis servo motor 12 stops. Next, as shown in FIGS. 3C to 3D, the table 7 moves rightward, and the grindstone 6 moves leftward relative to the workpiece W. Similarly, the grindstone 6 is cut by rough feeding in FIGS. In FIGS. 3E to 3F, the table 7 moves to the left. 3 (f) to 3 (g), the grindstone 6 is cut by rough feed. 3 (g) to 3 (h), the table 7 goes to the right. The grinding wheel 6 is cut by rough feed from FIG.

In the case of plunge cutting, when the coarse feed is switched as shown in FIG.
Is driven to maintain rough feed.

In the case where the rapid feed is ended as shown in FIG. 3A and enters the rough feed step in FIGS. 3 and 4, the grindstone 6 is moved relative to the workpiece W during the first short step of the rough feed step. The grindstone 6 is air cut without cutting.

As shown in FIGS. 5 (f) to 5 (g) (FIGS. 3 (a) to 3 (i), and FIGS. 4 (a) to 4 (b)), the roughing feed ends the grinding process at time t3.

At time t3, the X-axis servo motor 12
Is switched to a speed corresponding to the feed of the grindstone 6 becoming the finish feed as shown in (g) to (h) of FIG. At the same time, the numerical controller 13 controls the grindstone motor drive unit 14 to deactivate the grindstone motor 3 as shown in FIGS. Then, the grinding wheel 6 rotates by inertia after (k) in FIG.

From time t3 to time t4, as shown in FIGS. 5 (h) to 5 (o) (FIGS. 3 (i) to (j) and FIGS. 4 (b) to 4 (c)), Finishing feed is performed while repeating traverse. In the case of plunge cutting, cutting is performed uniformly by finishing feed. At time t4, as shown in (o) to (n) of FIG. 5, the X-axis servomotor 12 is deenergized to stop the grindstone head 2, and spark-out occurs. Between the time t3 and the time t5, the grindstone 6 and the grindstone motor 3
It rotates with the inertia force of the rotor or the like. And from time t3 to t
5, a reduction in transmission efficiency due to grinding resistance, friction loss between the grinding wheel shaft 4 and the bearing, friction loss of the belt device 5, etc.
5 due to friction loss with the bearing of the grinding wheel motor 3 and windage loss.
As shown in (k) to (m), the grinding wheel rotation speed decreases. However, no electromagnetic vibration is generated from the grindstone motor 3 from time t3 to t5 in FIG. Therefore, now
It is assumed that chatter vibration occurs from time t3 to t5. The chattering vibrations are as follows: (1) When the grinding wheel is unbalanced, the grinding wheel rotation speed N (rpm) and the vibration frequency n
(Hz), vibration of n = N / 60 occurs.
(2) Vibration generated by rotation of the grindstone motor 3; f: AC frequency (Hz) P: Number of motor poles n = 2 · f
/ P, (3) vibration caused by belt flutter, (4) vibration transmitted from a machine installed near an external grinding machine, and (5) the stator and rotor of the electric motor act as electromagnets. There are electromagnetic vibrations that occur. The vibration frequency n (Hz) of this electromagnetic vibration is n = 2 · f, where f is the AC frequency (Hz).

According to this embodiment, since the AC frequency f disappears, chattering does not occur under the condition that the electromagnetic vibration is generated.

From time t4 to t5, spark-out is performed as shown in (n) to (s) of FIG. 5 ((j) of FIG. 3, (c) of FIG. 4).

When the spark-out is completed at time t5, the X-axis feed motor 12 rotates reversely and rotates rapidly as shown in FIGS. 5 (s) to (t), the grindstone table 2 enters a rapid retreat, and the grindstone 6 is processed. 5 (p) of FIG.
To (q), the grindstone motor 7 is energized. When the grindstone motor 3 rotates, the grindstone rotation speed returns to the specified rotation speed as shown in (m) to (r) of FIG. Then, from time t5 to t6, the grindstone 6 is moved according to the grindstone table 2 as shown in (t) to (u) in FIG. 5 ((j) to (k) in FIG. 3 and (c) to (d) in FIG. 4). Gets away quickly from workpiece W.

At time t6, the X-axis servo motor 12 stops, and the grindstone table 2 stops as shown in FIG. At the same time, as shown in (w) to (x) of FIG.
Stops the rotation of the workpiece W.

As described above, since the grinding wheel motor 3 is not energized during the time from time t3 to time t5 in the finish grinding process, chatter marks due to chatter vibration based on electromagnetic vibration are generated in the workpiece W during rough grinding. Is removed during finish grinding and spark out. Also, even when the grinding wheel motor 3 is energized to generate chatter marks due to the chatter vibration based on the electromagnetic vibration when the grinding wheel motor 3 is energized, the chatter vibration does not occur because the grinding wheel motor 3 is deenergized. In addition, in FIG.
The grindstone motor 3 is energized to return to normal rotation. 6 to 8
The same applies to.

(Embodiment 2) In Embodiment 1 described above, the grinding wheel motor 3 was deenergized during the entire finishing grinding process.
In the second embodiment, the grindstone motor 3 is deactivated for a part of the time during the finish grinding.

FIG. 6 is a time chart showing the second embodiment. In FIG. 6, portions denoted by the same reference numerals and symbols as in FIG. 5 are the same as those in the first embodiment. Therefore, only points different from the first embodiment will be described.

In FIG. 6, at time t3, the grindstone motor 3 is continuously driven without deenergizing. From time t3, as shown in (g) to (h) of FIG. 6, the grinding wheel feed speed is reduced from the rough grinding to the finish grinding feed speed. Time t3
At a later time t3 ', during finish grinding, the grindstone motor 3 is deenergized as shown in (i') to (j ') in FIG. 6 and the grindstone 6 rotates by inertia from the time t3' to the time t5. At time t5, as shown in (p) to (q) of FIG.
Is urged, and the grindstone 6 is returned to the original rotation speed as shown in (m) to (r) of FIG. At time t4, the feed speed of the grinding wheel head 2 becomes zero as shown from (o) to (n) in FIG. The operation after time t5 is the same as in the first embodiment.

(Embodiment 3) FIG. 7 shows a modification of FIG.

FIG. 7 is a view in which spark-out is eliminated in FIG.

In FIG. 7, from time t0 to t4 (t4
The description of (except for the action at) is made at time t0 in the first embodiment.
From t4 to t4 (excluding the operation at t4), the description is the same as in the first embodiment.

At time t4 in FIG. 7, the X-axis feed motor 12 rotates reversely and rotates rapidly as shown in (o) to (n) in FIG. At the same time, the grindstone motor 3 is energized as shown from (p ') to (q') in FIG. When the grindstone motor 3 rotates, the grindstone rotation speed returns to the specified rotation speed as shown from (m ') to (r') in FIG.

The operation at time t5 in FIG. 7 is the same as the operation at time t6 in FIG.

(Embodiment 4) FIG. 8 shows a modification of FIG.

FIG. 8 is a view in which spark-out is eliminated in FIG.

In FIG. 8, from time t0 to time t4 (t4
The description of (except for the action at) is made at time t0 in the first embodiment.
From t3 to t3 (excluding the operation at t4), the description is the same as in the second embodiment.

At time t4 in FIG. 8, the X-axis feed motor 12 rotates reversely and rotates rapidly as shown in (o) to (n) in FIG. At the same time, the grindstone motor 3 is energized as shown from (p ') to (q') in FIG. When the grindstone motor 3 rotates, the grindstone rotation speed returns to the specified rotation speed as shown from (m ') to (r') in FIG.

The operation at time t5 in FIG. 8 is the same as the operation at time t6 in FIG.

FIGS. 9 and 10 show the vibration of the grindstone table 2. FIG. In the figure, the vertical axis indicates amplitude (G), and the horizontal axis indicates frequency (Hz). Note that G = 9.8 m / s ² .

In this measuring method, for example, a vibration sensor is provided on the grindstone table 2, input to a vibration analyzer, and measurement data is printed out from the vibration analyzer.

FIG. 9 shows a case where the grindstone motor 3 is kept energized during the time t3 to t5 shown in FIG. 5, and FIG. 10 shows a case where the grindstone motor 3 is deenergized during the time t3 to t5 shown in FIG. It is. FIG. 9 clearly shows that the grinding wheel base 2 is based on the electromagnetic vibration.
Is continuing to vibrate. In FIG. 10, the motor is deenergized, and the vibration is extremely small. This vibration is caused by imbalance of the grinding wheel or the rotating part of the grinding wheel motor, vibration of the belt device, and the like.

In the above description, the roundness of the workpiece was measured by a roundness measuring device in the case of FIG. 9 in which chatter marks due to electromagnetic vibration occurred in the workpiece during finish grinding. As a result of counting the total number of chatter marks, it was recognized that the vibration frequency n (Hz) = 2f = 2 × 50 = 100 when the AC frequency f (Hz) = 50.

Further, when the roundness of the workpiece was measured by a roundness measuring device in the case of FIG. 10, no chatter mark due to electromagnetic vibration was observed.

[0056]

According to the first aspect of the present invention, in a grinding method for grinding a workpiece using a grindstone, the grinding wheel motor is energized to rotate the grindstone motor and the workpiece is rotated. A first step of sending the grindstone and the workpiece closer to each other, a second step of roughly feeding and rough grinding while rotating the grindstone motor and the workpiece in the same manner as the first step, and When finishing grinding by feeding the finish following the process, during all or part of the finishing grinding, the grindstone is deenergized and the grindstone is rotated by the inertia of the moving part from the grindstone motor to the grindstone. The third method of performing finish grinding while continuing the rotating state is employed. (1) Even if chatter due to electromagnetic vibration occurs in the workpiece in the rough grinding, it can be removed by finish grinding.

(2) No chatter due to electromagnetic vibration occurs when chatter due to electromagnetic vibration occurs in the workpiece during finish grinding.

According to the second aspect of the present invention, when the grinding wheel motor is deactivated in the middle of the third step in the first aspect, the grinding wheel motor is deactivated following the third step. By using a grinding method including rotating the grindstone motor and rotating the workpiece and sparking out without giving a cutting feed, chatter due to electromagnetic vibration does not occur even when sparking out.

According to the third invention of the present application, in the first or second invention, the grinding step is a traverse cut.

According to the fourth aspect of the present invention, in the first or second aspect, the grinding step is a plunge cut.

According to the fifth invention of the present application, in the first invention, in the case where the grinding wheel motor is deenergized from the beginning of the third step, the spark-out step following the third step is entirely performed. Also, the spark-out is performed while maintaining the deenergized state of the grinding wheel motor in the third step. Thereby, the influence on the workpiece due to the electromagnetic vibration during the spark-out can be eliminated.

According to the sixth aspect of the present invention, in the first aspect, the grinding is performed by energizing the grinding wheel motor in a state where the grinding process is completed and the grinding wheel is separated from the workpiece. It can be repeated many times.

According to the seventh aspect of the present invention, in the second or fifth aspect, the grinding wheel is urged in a state in which spark-out is completed and the grinding wheel is separated from the workpiece, thereby performing grinding. Can be repeated many times.

[Brief description of the drawings]

FIG. 1 is a plan view of a cylindrical grinding machine.

FIG. 2 is a plan view of a crankpin grinding machine.

FIG. 3 shows a tool path of a traverse cut of the cylindrical grinding machine of FIG. 1;

FIG. 4 shows a tool path of plunge cutting of the crankpin grinding machine of FIG.

FIG. 5 is a time chart according to the first embodiment.

FIG. 6 is a time chart according to the second embodiment.

FIG. 7 is a time chart according to the third embodiment.

FIG. 8 is a time chart according to the fourth embodiment.

FIG. 9 shows a vibration waveform of a grinding wheel head where electromagnetic vibration occurs.

FIG. 10 shows a vibration waveform after the grinding wheel motor has been deenergized.

[Explanation of symbols]

 W: Workpiece t0 to t6: Time 1: Machine stand 2: Grinding wheel electric motor 4: Grinding wheel shaft 5: Belt device 6: Cylindrical grindstone 7: Table 9: Workpiece head 11: Tailstock 12: X axis Servo motor 13 Numerical controller 14 Drive unit

Claims (7)

[Claims] 1. A grinding method for grinding a workpiece using a whetstone, wherein a whetstone motor is energized to rotate the whetstone motor, and the whetstone and the workpiece are sent closer to each other while the workpiece is rotated. A second step of performing rough feed and rough grinding while rotating the grindstone motor and the workpiece in the same manner as in the first step, and a finish feed by rotating the workpiece following the second step When performing finish grinding during all or part of the finish grinding,
A third step of de-energizing the grindstone motor and performing finish grinding in a state where the grindstone is continuously rotated by the rotational force due to inertia of the moving part from the grindstone motor to the grindstone. 2. In the case where the grinding wheel motor is deactivated during the third step, the grinding wheel motor is rotated while the grinding wheel motor is deenergized, and the workpiece is rotated and cut and fed after the third step. The grinding method according to claim 1, further comprising a step of sparking out without providing the surface. 3. The grinding method according to claim 1, wherein the grinding step is a traverse cut. 4. The grinding method according to claim 1, wherein the grinding step is a plunge cut. 5. When the grinding wheel motor is deenergized from the beginning of the third step, the deenergized state of the grinding wheel motor in the third step is maintained in all of the spark-out steps following the third step. The grinding method according to claim 1, wherein spark-out is performed as it is. 6. The grinding method according to claim 1, wherein the grinding wheel motor is energized in a state where the grinding wheel is separated from the workpiece after the third step is completed. 7. The grinding method according to claim 2, wherein the grinding wheel motor is energized in a state where the grinding wheel is separated from the workpiece after the spark-out is completed.