JPH0453677A - Electric discharge truing device - Google Patents

Abstract

PURPOSE:To make a grinding wheel outer peripheral face flat inexpensively by advancing an electrode in a microquantity when a truing electric discharging is less than the shortest electric discharging time, performing a constant speed cross-feed in case of its being between the shortest and longest electric discharging times, and completing electric discharge truing when reaching the longest electric discharging time. CONSTITUTION:An electric discharge truing is started on the most projected part of a grinding wheel 1 while crossfeeding an electric discharging electrode 2 in the axial direction of a metal bond grinding wheel 1 by a crossfeeding mechanism 11. When the electric discharging time detected by an electric discharging detection mechanism 14 is over the shortest electric discharging time, an over-signal is output and the electric discharge truing of the most projected part is performed while performing the cross feed of the electrode by the crossfeeding mechanism 11 with the command of a controller 15. When the electric discharging time during one crossed stage becomes short and insufficient for the shortest electric discharging time, a shortage signal is output, an advancing and retreating mechanism 8 is operated and the electrode is advanced in a micro-quantity at the end of the crossfeed stage. Thus, an over- signal is output, when the electric discharging time becomes longer and exceeds the shortest electric discharging time and the electric discharge truing is performed while performing the crossfeed only of the electrode.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a discharge truing device for a metal bond grinding wheel in which non-conductive abrasive grains made of diamond or CBN are bonded with a conductive metal such as a copper alloy. .

[Conventional technology]

Conventionally, the above-mentioned discharge truing device has been equipped with a discharge electrode, a discharge power source connected to the electrode and the metal bond grindstone to cause a discharge between them, an advancing/retracting mechanism for moving the electrode back and forth in the radial direction of the grindstone, and the above-mentioned. Some were equipped with a transverse feed mechanism that reciprocated in the axial direction of the grindstone, and a control device that drove these mechanisms.

In this discharge truing device, the advancing and retracting mechanism and the traversing mechanism are driven by inter-electrode voltage feed hack control by the control device so that the distance between the electrode and the grinding wheel is constant, and the electrode is moved to the grinding wheel. The outer periphery of the grindstone is trued by causing an electric discharge between the electrode and the grindstone while moving the electrode back and forth in the radial direction of the grindstone and reciprocating in the axial direction of the grindstone.

[Problem to be solved by the invention]

However, the conventional discharge truing device described above is
As illustrated in the figure, if there is an uneven portion in the axial direction on the outer peripheral surface of the metal bonded grinding wheel 1, the electrode 2 follows the shape of the grinding wheel 1 so that the voltage between the electrodes and the grinding wheel 1 is constant. Since the grinding wheel is moved back and forth and moved laterally, there is a problem in that the outer circumferential surface of the grindstone cannot be made flat without any unevenness.

This invention attempts to solve the above-mentioned problems, and it is possible to make the outer circumferential surface of the metal bonded grindstone flat without unevenness, which is similar to a numerical (NC) control device or a feedbank control device. It is an object of the present invention to provide a discharge truing device that can be automatically operated by a control device that can be obtained at low cost without using expensive equipment.

[Means to solve the problem]

The present invention provides a control device for controlling an advance/retreat mechanism for advancing and retracting the discharge electrode in the radial direction of the metal bond grindstone and a lateral feed mechanism for moving the discharge electrode back and forth in the axial direction of the grindstone in the discharge truing device as described above. , a discharge detection mechanism that outputs a detection signal of the shortest and longest discharge time during one traverse stroke of the electrode, and a discharge detection mechanism that receives the detection signal of this detection mechanism and detects that the truing discharge is less than the shortest discharge time at the end of the traverse stroke. The electrode is moved forward by a minute amount by the advancing and retracting mechanism, and when the discharge time is between the shortest and longest discharge time, the electrode is only moved horizontally at a constant speed by the traversing mechanism, and when the discharge reaches the longest discharge time, the electrode is moved forward by a small amount. A controller is provided to move the electrode backward and terminate discharge truing.

[For production]

The discharge truing device according to the present invention starts discharge truing on the most convex part of the grindstone while laterally feeding the discharge electrode in the axial direction of a metal bond grindstone having an uneven surface on its outer peripheral surface using a transverse feed mechanism, and uses a discharge detection mechanism to When the discharge time is detected and this time exceeds the shortest discharge time, the detection mechanism detects this and issues an excess signal, which is received by the controller. The height of the most convex part is reduced by carrying out discharge truing of the most convex part for one or more traversal strokes while only transversely feeding the electrode. As a result, the discharge time during one traversal stroke becomes shorter, and when the shortest discharge time is insufficient, the detection mechanism detects this and issues an insufficient signal, which is received by the controller, and the controller commands to move forward or backward. The mechanism is actuated to advance the electrode a small amount at the end of the traverse stroke. This advancement lengthens the discharge time during one traverse stroke, and when the shortest discharge time is exceeded, the detection mechanism issues an excess signal and discharge truing is performed while only transversely transporting the electrode via the controller.

By repeating the above-mentioned operation, the convex part of the grinding wheel is gradually lowered, the outer peripheral surface of the grinding wheel is made flat, and the discharge time during one traversal stroke is lengthened, and when this time reaches the maximum discharge time, this The detection mechanism detects and issues an arrival signal, which is received by the controller, and the controller operates the advancing/retracting mechanism in accordance with the commands to move the electrode back and forth, thereby completing the discharge truing.

Therefore, the present invention continuously and automatically performs discharge truing from the start to the end by a control device having a detection mechanism and a controller, and eliminates the protrusion in the axial direction on the outer circumferential surface of the grinding wheel. can be made flat.

Further, the detection mechanism may be one that detects the shortest and longest discharge times during one lateral movement of the electrode and causes the controller to receive these detection signals, and this controller receives the signals and moves the electrode forward or backward. Since it is only necessary to control the mechanism and the traversing mechanism, there is no need to use expensive devices such as a numerical control device or a feedback control device.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, in the discharge truing device according to this embodiment, a roll-shaped electrode 2 is mounted on a head 3 so as to be rotated about an axis by an electric motor 4 provided thereon. The head 3 includes a support base 5, a motor 6 provided on the support base 5, and a screw shaft 7 rotated by the motor 6.
The metal bond grinding wheel 1 provided on the grinding machine can be moved forward and backward in the radial direction by a forward and backward movement mechanism 8 having the following. The support base 5 is moved by a transverse feed mechanism 11 having an appropriate member (not shown) of the grinding machine that supports the support base 5, an electric motor 9 provided on this member, and a screw shaft 10 rotated by the electric motor 9. is capable of reciprocating along the axial direction of the grindstone 1. The electrode 2 and the grindstone 1 are connected to a discharge power source 12.

A control device 13 that controls the advancing and retracting mechanism 8 and the traversing mechanism 11 is provided with a discharge detection mechanism 14 and a controller 15. In the detection mechanism 14, a voltmeter 16 is connected to a discharge circuit that connects the discharge power source 12 and the grindstone 1, and a discharge circuit that connects the discharge power source 12 and the electrode 2. An ammeter 17 is provided in the discharge circuit connecting the electrode 2 and the electrode 2 . A signal is output from the shortest discharge time counter 18 and the longest discharge time counter 19 to which voltage values and current values are input from the voltmeter 16 and ammeter 17 via a comparison circuit 20 and a comparison circuit 21. There is. The controller 15 receives a signal from the detection mechanism 14 and connects a drive circuit 22 for the electric motor 6 provided in the advance/retreat mechanism 8 and a drive circuit 2 for the electric motor 9 provided in the traversing mechanism 11.
It is configured to give commands to the electrodes 3 and 3 to cause the electrodes 2 to move forward and backward and move laterally.

Next, the truing operation by the discharge truing device of this embodiment will be performed according to the flowchart shown in FIG. 2, with high and low convex portions 1a,
A case will be described in which the grinding wheel 1 has a concave portion and a concave portion.

First, the grinding wheel 1 and the electrode 2 are made to face each other, and the controller 15 of the control device 130 is activated to give a command to the drive circuit 22 to drive the electric motor 6 of the advancing/retracting mechanism 8 in the forward rotation. Move forward rapidly in the radial direction. When the electrode 2 advances close to the discharge distance to the high convex portion 1a of the grinding wheel 1, the controller 15 is actuated by an appropriate means to give a command to the drive circuit 23,
By driving the electric motor 9 of the transverse feed mechanism 11, the electrode 2
is reciprocated along the axial direction of the grindstone 1 at a predetermined speed for a predetermined distance to perform lateral feeding. At the same time, a command is also given to the drive circuit 22 to switch the rapid forward movement of the electrode 2 by the advancing/retracting mechanism 8 to the minute fixed amount forward movement of the electrode 2 at both ends of the reciprocating movement by the lateral feeding mechanism 11 . Note that the transverse movement of the electrode 2 may be performed at the same time as the start of the rapid movement or at an appropriate time before switching to minute quantitative advancement. In addition, at a timely period from the start of rapid forwarding of the electrode 2 to the time of switching to minute quantitative forwarding, the grinding wheel 1 and the electrode 2 are rotated around their respective axes, and the discharge power source 12 is turned on by a command from the controller 15. .

As shown in FIG. 3A, the electrode 2 faces the high convex portion 1a of the grinding wheel 1 by the above-mentioned traversal feeding and minute advance, and when the distance between them reaches the discharge distance, discharge truing is started. The shortest and longest discharge time counters 1B and 19 detect this discharge time. That is, when the discharge power supply 12 is turned on, the voltmeter 16 and the ammeter 17 always send the voltage value and current value to the shortest and longest discharge time counters 18 and 19, and these counters 1B and 19 during one traverse stroke, In other words, 1 of electrode 2
The voltage value during the forward or backward movement is measured as a pulse. Before the start of discharge, as shown in FIG. 4A, the voltage has a waveform with peaks at regular time intervals, and the current has a straight line with no peaks.

When the discharge starts, the voltage increases in the discharge section and the peak is captured, resulting in a waveform in which a peak appears in the current, as shown in FIG. 4B. These measured values are sent from the shortest and longest discharge time counters 1B and 19 to the comparison circuit 20.21, and the shortest and longest discharge time counters 1B and 19 are sent to the comparator circuit 20.
Compared to the longest discharge time.

Figure 4B shows the case of the set shortest discharge time, and the third
Since the discharge time has not reached the set minimum discharge time at the discharge start time in Figure A, the electrode 2 moves forward by a small amount at one end of the lateral movement. This advance causes the discharge time to become longer (as illustrated in FIG. The excess signal is sent to the controller 15. The controller 15 that received this excess signal
gives a stop command to the drive circuit 22 to stop the advancement of the electrode 2 by the advance/retreat mechanism 8, and the electrode 2 continues to be moved only laterally.

In this state, each time the electrode 2 passes a high convex portion 1a of the grinding wheel 1, that is, every traversal stroke, the high convex portion 1a is subjected to discharge truing from the most convex portion, and its height decreases.

Then, when the electrode 2 is traversed by more than one traverse stroke and the height of the high convex portion 1a becomes lower as shown in FIG. When the set minimum discharge time reaches or becomes shorter than the set minimum discharge time of 20, the comparator circuit 20 outputs a shortest discharge time insufficient signal. Upon receiving this shortage signal, the controller 15 gives a drive command to the drive circuit 22, and when the electrode 2 is located at one end or the other end of the traverse stroke by the traverse feed mechanism 11, the electrode 2 is advanced by a minute amount by the advance/retreat mechanism 8. let

Due to this advance, the discharge time becomes longer than the shortest discharge time set in the comparator circuit 20, so the comparator circuit 20 sends the shortest discharge time excess signal again to the controller 15, and the drive circuit 22
A stop signal is given to the electrode 2, and the forward movement of the electrode 2 by the advancement/retraction mechanism 8 is stopped, and the high convex portion 1 becomes lower while continuing to move only horizontally.
Alternatively, discharge truing is performed on this and the low convex portion 1b.

By repeating the above-mentioned operation in the cycle illustrated in FIG. 5, the high and low convex portions 1a and lb gradually become lower, and the outer circumferential surface of the grinding wheel 1 becomes nearly flat in the entire axial direction. The discharge time during one traverse stroke becomes longer. When the outer circumferential surface of the grinding wheel l becomes flat over its entire axial length, the measured value by the longest discharge time counter 19 reaches the set longest discharge time stored in the comparator circuit 21, and the comparator circuit 21 outputs a set longest discharge time arrival signal. That is, a discharge truing end signal is issued. Upon receiving this signal, the controller 15 gives a command to the drive circuit 22 to drive the electric motor 6 of the advancing/retracting mechanism 8 in reverse to move the electrode 2 back and forth rapidly and return it, and also gives a command to the drive circuit 23 to The electric motor 9 of the transverse feed mechanism 11 is stopped so that the electrode 2 returns to the position before operation. Furthermore, the discharge power supply 1
2 is turned off, the rotation of the grindstone 1 and the electrode 2 around the axis is also stopped, and the discharge truing is completed.

In addition, in the above explanation, the electrode 2 and the high convex part 1a of the grinding wheel 1
We have described the case where the discharge time is shorter than the set minimum discharge time when the discharge starts between the The time becomes longer than the set minimum discharge time, and discharge is performed while only moving the electrode horizontally.

Moreover, although the case where the grindstone 1 has the high and low convex parts 1a and lb has been described, the present invention can also be applied to the case where the grindstone has one convex part or three or more convex parts.

Furthermore, the discharge detection mechanism according to the present invention is not necessarily limited to the configuration of the embodiment, and can be modified as appropriate as long as it outputs a detection signal of the shortest or longest discharge time during one lateral movement of the electrode. may be zero, that is, there is no discharge, and in this case, the shortest time detection mechanism can be simplified.

Switching the electrode from rapid advance to minute quantitative advance is performed by manual operation of the controller or automatic operation by an appropriate detection means, and the rapid advance may be omitted depending on the case.

[Effects of the Invention] As explained above, the present invention includes a discharge electrode, a discharge power source that is connected to the electrode and the metal bond grindstone and causes a discharge between them, and that moves the electrode back and forth in the radial direction of the grindstone. In the discharge truing device, the electric discharge truing device includes an advancing/retracting mechanism, a lateral-feeding mechanism that reciprocates in the axial direction of the grindstone, and a control device that controls the advancing/retracting mechanism and the lateral-feeding mechanism. A discharge detection mechanism that outputs a detection signal of the shortest and longest discharge time during one traverse stroke, and upon receiving the detection signal of this detection mechanism, if the truing discharge is less than the shortest discharge time, the electrode is moved back and forth at the end of the traverse stroke. The mechanism moves the electrode forward by a small amount, and when the discharge time is between the shortest and longest discharge time, the traversal mechanism causes the electrode to move only at a constant speed, and when the discharge reaches the longest discharge time, the electrode is moved backward. Since a controller for terminating the discharge truing is provided, the following effects can be obtained.

That is, the discharge truing device according to the present invention starts discharge truing to the most convex part of the grindstone while transversely feeding the discharge electrode in the axial direction of the metal bond grindstone having unevenness on the outer peripheral surface using the transverse feed mechanism, and performs discharge detection. The discharge time is detected by the mechanism, and if this time exceeds the shortest discharge time, the detection mechanism detects this and issues an excess signal, which is received by the controller, and the controller commands the traverse feed mechanism. The height of the most convex part is reduced by carrying out discharge truing of the most convex part for one or more traverse strokes while only transversely moving the electrode. As a result, the discharge time during the traversal stroke becomes shorter, and when the shortest discharge time becomes insufficient, the detection mechanism detects this and issues an insufficient signal, which is received by the controller, and the controller commands the robot to move forward or backward. The mechanism is actuated to advance the electrode a small amount at the end of the traverse stroke. This advancement lengthens the discharge time during one traverse stroke, and when the shortest discharge time is exceeded, the detection mechanism issues an excess signal and discharge truing is performed while only transversely transporting the electrode via the controller. By repeating the above-mentioned operation, the convex part of the grindstone is gradually lowered,
While flattening the outer peripheral surface of the grinding wheel, the discharge time during one traverse stroke is lengthened, and when this time reaches the maximum discharge time,
The detection mechanism detects this and issues an arrival signal, which is received by the controller, and the controller operates the forward/backward movement mechanism to move the electrode back and forth, thereby terminating the discharge true ink. Therefore, the present invention continuously and automatically performs discharge truing from the start to the end by a control device having a detection mechanism and a controller, and eliminates the protrusion in the axial direction on the outer circumferential surface of the grinding wheel. can be made flat.

In addition, the detection mechanism is the shortest in one horizontal movement of the electrode.

It is sufficient to detect the longest discharge time and send these detection signals to a controller, and this controller only needs to control the advance/retreat mechanism and the lateral feed mechanism upon receiving the signals, so it is not necessary to use a numerical control device or It is not necessary to use an expensive device such as a feedback control device.

[Brief explanation of drawings]

Fig. 1 is a configuration explanatory diagram showing a discharge truing device according to an embodiment of the present invention, Fig. 2 is a flow chart for explaining the operation of the discharge truing device of Fig. 1, and Figs. 3 A and B are at the start of discharge truing. Figure 4 A, B, and C are before discharge. A waveform diagram showing the voltage and current at the set minimum discharge time and a discharge time longer than the set minimum discharge time, Fig. 5 is a cycle explanatory diagram showing the relationship between minute quantitative advance and lateral movement of the electrode, and Fig. 6 is the conventional one. FIG. 3 is an explanatory diagram showing the positional relationship between a metal bond grindstone and a discharge electrode in the discharge truing device. 1...Metal bond grindstone, 2...Discharge electrode, 8...
・Advance/backward mechanism, 11... Lateral feed mechanism, 12... Discharge power source, 13... Control device, 14... Discharge detection mechanism,
15... Controller, 16... Current needle, 17...-Voltmeter, 18.19... Shortest and longest discharge time, 2
0.21... Comparison circuit, 22.23... Drive circuit. Fang Zu Zuzu (θ Nora Zu (C) Tooth Zuzu 94 no Saizu ♂ rj!J (β) U4 Diagram (A) Tooth Zu Zu Saizu

Claims (1)

[Scope of Claims] A discharge electrode, a discharge power source connected to this electrode and a metal bond grindstone to cause a discharge between them, an advancing/retracting mechanism for advancing and retracting the electrode in the radial direction of the grindstone, and an axial direction of the grindstone. In the discharge truing device, the discharge truing device includes a cross-feeding mechanism that reciprocates and cross-feeds the electrode, and a control device that controls the advancement/retraction mechanism and the cross-feeding mechanism, wherein the control device is configured to control the shortest and longest movement of the electrode during one cross-feeding stroke. a discharge detection mechanism that outputs a discharge time detection signal; and upon receiving the detection signal of this detection mechanism, if the truing discharge is less than or equal to the shortest discharge time, the electrode is advanced by a minute amount by the advance/retreat mechanism at the end of the traverse stroke; When the discharge time is between the shortest discharge time and the longest discharge time, the traversal mechanism causes the electrode to be traversed at a constant speed, and when the discharge reaches the maximum discharge time, the controller moves the electrode backward to end the discharge truing. A discharge truing device characterized by being provided with.