JPS6023944B2 - Workpiece grinding control device - Google Patents

Description

[Detailed Description of the Invention] This invention provides a traverse cutting method for grinding.
The present invention relates to a workpiece grinding control device that prevents the formation of steps on the grinding surface, improves processing efficiency, and improves processing accuracy such as cylindricity.

For example, in an internal grinding machine, when grinding the inner surface of a hole in a workpiece, continuous cutting feed is applied to the cutting table, and the grinding wheel table or work table is moved in reciprocating motion.

The so-called traverse cut method is adopted. However, although this traverse cut method does not pose such a problem when grinding a workpiece whose thickness is smaller than the workpiece diameter, it is difficult to use the traverse cut method to grind the inner surface of a long hole in a workpiece whose length is three times or more than the workpiece diameter. When grinding is performed, the internal dimension of the workpiece in the axial direction changes as shown by the zigzag arrow line in FIG. 1, and a difference occurs between the insertion side a of the grindstone relative to the workpiece and the opposite side b. For this reason, for example, when the in-process sizing device picks up the light dimension of the workpiece at the position of line 1 in Fig. 1, the sizing signals at each sizing point S, S2, etc. due to changes in the workpiece dimension will be As shown in Figure 2, it becomes a staircase shape, and as is clear from the figure, sizing signals with different staircase levels are generated alternately.
If the sizing position is placed at the center of the workpiece in the axial direction, a step-like sizing signal of a certain level will be obtained. Also, as shown in Fig. 1, when the grinding wheel 1 is partially out of the a side (backward end) of the workpiece W or protrudes from the b side (forward end), the workpiece diameter has reached the target dimension. If the cutting table is moved back quickly,
The finished surface of the workpiece has the shape shown by ABE or AS30 in Fig. 1, so there is no problem with the machining accuracy and cylindricity of the workpiece. When the diameter of the workpiece reaches the target size, the cutting table will naturally be reversed quickly, so the inner surface of the workpiece will have a shape that connects ABCD as shown in Figure 1, resulting in a step This results in loss of cylindricity. In addition, when controlling the remaining cut amount of the grinding machine using the stepped sizing signal described above, the cutting operation of the cutting table for controlling the remaining cut amount is based on the machining dimension signal and the cutting position signal detected by the in-process sizing device. A method is adopted in which the cutting speed of the cutting drive system is controlled so that the remaining cutting amount (cross-cutting amount) due to the difference between the two is maintained at a preset remaining cutting amount. Therefore, when the machining dimension signal detected by the in-process sizing device changes stepwise, the cutting speed is controlled intermittently only at the time when this dimensional change appears. In such a situation, the shape accuracy and machining accuracy of the workpiece cannot be expected at all, so the signal detected by the in-process sizing device is smoothed and converted into a continuous machining dimension change signal, and the cutting speed of the cutting drive system is continuously adjusted. Therefore, it is necessary to carry out specific control.

Therefore, the present invention smoothes the stepped machining dimension signal detected by the in-process sizing device, and maintains the uncut amount (cutting amount) due to the difference between this smoothed signal and the cutting position signal at a preset uncut amount. The cutting speed of the cutting drive system is controlled so that the cutting speed of the cutting drive system can be controlled so that the cutting speed of the cutting drive system can be controlled so that the cutting speed of the cutting drive system can be stopped. To provide a workpiece grinding control device which eliminates steps caused by grinding.

Embodiments of the present invention will be described below with reference to FIGS. 3 and 4.

FIG. 3 shows a block diagram of the workpiece grinding control device according to the present invention, and 1 schematically shows an internal grinding machine, and this internal grinding machine 1 has a slide table 3 on one side of the leg 2. The grinding wheel spindle head 4 installed through the
A cutting table 6 installed on the other side of the top via a slide table 5
The cutting table 6 is movable in a direction perpendicular to the moving direction of the grindstone spindle head 4, and a servo motor 7 is attached to the chest 2 to feed the cutting table 6. There is. Further, a workpiece W is set on the cutting table 6 to be gripped by a workpiece spitwaddle head (not shown). Reference numeral 8 denotes an in-process sizing device installed on the cutting table 6, and this sizing device 8 continuously measures the machining dimensions of the workpiece W.

Further, 9 is a position detection device for detecting the cutting position of the cutting table 6 installed on the fixed table 5, and 10 is a dressing device for correcting the grinding wheel 4a of the grinding wheel spindle head 4. Each time the grindstone 4a is dressed, a cutting table 6 is sent in to correct the absolute position of the dresser tip with respect to the grindstone surface. Reference numeral 11 denotes an arithmetic circuit for calculating the remaining cutting amount (cutting amount) during workpiece grinding, and the machining dimension signal output from the in-process sizing device 8 is sent to this arithmetic circuit 11 through an amplifier 12 and a smoothing circuit 13. At the same time, the cut position signal output from the position detection device 9 is also introduced via the amplifier 14, and the difference signal between the two, which is the uncut amount (cutting amount) movement, is calculated. Further, first and second set uncut amounts g, , g2 of coarse grinding and coarse grinding are set in this comparison circuit 15 via a switching circuit 16, and setting signals g, , , g2 are set. An uncut amount setting circuit 17 that outputs the standard value is connected.

Reference numeral 18 is a Schmitt circuit connected to the output side of the smoothing circuit 13, and this Schmitt circuit 18 is used to change the machining dimensions of the workpiece W from the target dimensions by an amount that leaves a constant value of grinding margin as small as possible, that is, from rough grinding to fine grinding. When switching to the first
When the target size is reached, the second signal Ps,
s2, and each of these signals operates the cut-off circuit 16 to separately introduce each set remaining amount g, , & from the setting circuit 17 into the comparison circuit 15, and the above-mentioned The deviation signal output from the comparator circuit 15 by comparison with the uncut amount signal introduced from the arithmetic circuit 11 is introduced into the servo motor drive control circuit 19 to control the servo motor drive control circuit 19. The cutting table 6 is driven so that the deviation output from the comparator circuit 15 is zero, that is, the set uncut amount g or & is maintained.
The cutting speed is controlled.

Further, 20 is a position detector that detects the position of the forward end or backward end of the slide table 3 during the reciprocating movement, and this position signal is introduced as a trigger input to the gate circuit 21. At the same time,
A second signal Ps2 from the Schmitt circuit 18 is introduced into the gate circuit 21, and the output of both signals gives a command to stop the cutting control to the servo motor drive control circuit 19, and simultaneously controls the cutting system. This is a fast rewind operation.

Next, the operation of the inventive device configured as described above will be explained.

First, each uncut amount g in rough grinding and fine grinding, axis (
g,》&) to a predetermined value, i.e. g at the time of first stage rough grinding.
, is a value that enables efficient grinding of the workpiece stock and improves shape accuracy, and the step in the second stage of mill grinding is made as small as possible to grind the stock in a short time and reduce surface roughness. and adjust the shape accuracy and set the values to improve the cylindricity.

In this state, the grinding wheel spindle head 4 is advanced in the direction of the workpiece W, and with the grinding wheel 4a inserted into the grinding hole of the workpiece W, the entire spindle head 4 is rotated at a constant speed. Exercise reciprocation in the park. Then, a cutting command is given to the servo motor 7 of the cutting table to infeed the cutting table 6. FIG. 4 shows the relationship between grinding time, depth of cut, workpiece diameter, and uncut amount. The cutting table 6 cuts at a constant gap ferrimination speed V, and the workpiece W and the grinding wheel 4a When the grinding wheel comes into contact with the grinding wheel and the grinding wheel shaft begins to grind to a certain extent, the amount of uncut material (cross-cutting amount) caused by this occurs as shown in Fig. 4-1, and when the predetermined amount of uncut material is reached, The in-process sizing device 8 starts measuring the dimensions of the workpiece W.

At this time, the machining dimension signal continuously sent out from the sizing device 8 becomes step-like as shown in FIG. When introduced into the conversion circuit 13, its output side becomes a machining dimension signal 0' which changes linearly.

This dimension signal is introduced into the arithmetic circuit 11, and at the same time, the two are subtracted by the cut position signal introduced from the position detection device 9, and the deviation signal trajectory is supplied to the comparison circuit 15. This comparison circuit 15 compares the first setting value g, which is input from the uncut amount setting circuit 17 via the switching circuit 16, and the deviation signal, so that the difference between the two becomes zero, that is, g,=base. Then, the servo motor drive control circuit 19 and the servo motor 7 are operated to control the cutting speed of the cutting table 6. As a result, the workpiece W is ground while maintaining the uncut amount & set by the setting circuit 16. In this state, the machining dimension of the workpiece becomes a predetermined value, that is, a value that leaves a constant grinding margin as small as possible (several tens of microns) from the target dimension, and the signal from the in-process sizing device 8, that is, the smoothing circuit 13, is sent to the Schmitt circuit 18. When the first signal Ps, which is to be operated, is activated, the cutting gate circuit 16 is operated by this signal Ps, and the second uncut setting price is supplied to the comparison circuit 15 from the setting circuit 17.

At this time, the cutting table 6 has been overfed due to the large remaining amount during rough grinding, so the cutting table 6 rapidly retreats to a position where the amount of remaining cutting becomes the second set remaining amount g2. The servo motor drive control circuit 19 is operated to control the cutting table 6 at a speed that maintains the uncut amount g2. When the second signal Ps2 reaching the final dimension (target dimension) for operating the Schmitt circuit 18 is generated from the sizing device 8, that is, the smoothing circuit 13, the conversion circuit 16 returns to its original state, that is, from the setting circuit 17. At the same time that the state is returned to supplying the first uncut set amount g, to the comparator circuit 15, the second signal Ps2 is also introduced to the gate circuit 21, and the grinding wheel spindle head 4 is caused to move by reciprocation movement. When the forward end position or the backward end position is reached, it is confirmed by the position detector 20', and a confirmation signal is generated at the same time.When this is input to the gate circuit 21, this signal and the above-mentioned Schmitt circuit 18 output it. It opens in the gate circuit 21 by AND with the signal Ps2, gives a cutting operation stop command to the servo motor drive control circuit 19, and at the same time causes the cutting table 6 to perform a fast return operation. This completes the workpiece grinding cycle. In addition, in FIG. 4, a curve m indicates a positioning signal of the cutting table 6. Thereafter, the above-mentioned grinding operation is performed cyclically every time the workpiece W is ground in the same way, and the sizing signal from the Schmitt circuit 18 when the machining dimension of the workpiece W reaches the target dimension, and the sizing signal of the workpiece W
Grinding wheel position detector 2 when the contact position of the grinding wheel 4a reaches the forward end or the backward end where the grinding wheel 4a protrudes from the workpiece grinding hole
A quick return command is given to the cutting system only by the band output of the gate circuit 21 to which a position signal from 0 is applied. Therefore, the grinding wheel is returned by advancing the front end or detecting the backward end. Because the process never stops, there is no difference in the shape of the workpiece.

In addition, in the above-mentioned embodiment, the grinding wheel spindle head 4
The faster the reciprocation movement cycle, the better.
Furthermore, the smaller the depth of cut per reciprocation, the more advantageous.

In addition, the present invention is of course applicable not only to the internal grinding described above, but also to cylindrical grinding, etc. Furthermore, after retracting the first setting uncut amount that was overfed during rough grinding, the second setting Instead of controlling the set uncut amount to be constant, retraction may be performed to a position where the set uncut amount is constant, and in this state, the cutting table may be sparked out to perform grinding.

As described above, according to the device of the present invention, in a grinding machine that performs traverse grinding, step-like machining dimensions generated from the in-process sizing device are smoothed, and uncut portions due to the difference between this smoothing signal and the cutting position signal are Since we have adopted a method to control the cutting speed of the cutting drive system so that the cutting amount (crosscutting amount) can maintain the preset remaining cutting amount, there is no problem in controlling the remaining cutting amount of the grinder. The shape accuracy and processing accuracy of the workpiece can be improved.

In addition, even if a sizing signal is generated indicating that the machining dimensions of the workpiece have reached the target dimensions, the cutting system will not work until the contact signal of the grinding wheel on the workpiece reaches the forward end or backward end, where the grinding wheel protrudes from the workpiece grinding hole. Since a quick return command is not given, there is no stoppage during workpiece grinding, so there is no difference in level on the workpiece grinding surface unlike in the past.
Therefore, the cylindricity of the workpiece is improved.

[Brief explanation of the drawings] Figure 1 is an explanatory diagram showing dimensional changes due to traverse grinding.
FIG. 2 is an explanatory diagram showing the relationship between grinding time, depth of cut, and leak diameter in the conventional method, FIG. 3 is a block diagram showing an example of a workpiece grinding control device according to the present invention, and FIG. FIG. 3 is a diagram showing the relationship between time, depth of cut, workpiece diameter, and amount of uncut material. W...Work, 3...Slide stand, 4
...Whetstone spindle, 4a...Whetstone,
6... Cutting table, 7... Servo motor, 8... In-process sizing device, 9. Ri... Cutting position detection device,
11... Arithmetic circuit, 13... Smoothing circuit,
15...Comparison circuit foundation, 16...Switching circuit, 17...Remaining cut amount setting circuit, 18...
Schmitt circuit, 19... Servo motor drive control circuit, 20... Grinding wheel position detector, 21...
...It is a gate circuit. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 A continuous cutting traverse grinding system that performs continuous cutting traverse grinding, which continuously performs cutting feed motion regardless of the traverse movement between the grinding wheel and the workpiece and the relative position of the grinding wheel and the workpiece in this traverse movement. In the grinding machine,
During traverse motion, a grindstone position detector detects the traverse forward end or traverse backward end of the grindstone with respect to the workpiece in the traverse motion direction; a cut position detection device detects the cut position of the cutting table; A servo motor for feeding the depth of cut, an in-process sizing device for detecting the machining dimensions of the workpiece, and an output signal of a smoothing circuit for smoothing the stepped machining dimension signal generated from the in-process sizing device. a calculation circuit that calculates the difference between the position detection signal of the cutting position detection device and the position detection signal of the cutting position detection device, and outputs the remaining cut amount g_0; a comparator circuit that receives the output signal of an uncut amount setting circuit that sets and outputs one of the uncut amounts g_1, g_2 via a switching circuit; is connected between a servo motor drive control circuit that controls the smoothing circuit and the switching circuit, and when the machining dimensions of the workpiece become a value that leaves a predetermined grinding allowance from the target dimension by the output of the smoothing circuit. A first signal for switching the remaining cutting amount setting signal of the remaining cutting amount setting circuit from the remaining cutting amount g_1 during rough grinding to the remaining cutting amount g_2 during fine grinding and the cutting when the machining dimension of the workpiece reaches the target dimension. a Schmitt circuit that outputs a second signal for restoring the remaining cut amount setting signal to the remaining cut amount g_1 during rough grinding to the switching circuit; further, a second signal of the Schmitt circuit and an output signal of the grindstone position detector; A workpiece grinding control device comprising: a gate circuit which receives a cutting stop command to the servo motor drive control circuit and outputs a quick return signal for the cutting table from the servo motor drive control circuit to the servo motor.