JPS603552B2 - Grinding machine control method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shoe-type centerless grinder control method and apparatus for adjusting the grinding feed according to the magnitude of the friction coefficient between the workpiece and the shoe.

A shoe-type centerless grinder, in other words, the two shoes are used to level the workpiece in the radial direction, and the driver plate is used to position the workpiece in the axial direction.At the same time, this gives rotation to the workpiece, which connects the workpiece and the driver plate. For example, when producing a large number of circular workpieces on a production line with a shoe-type centerless grinding machine that uses magnets to achieve close contact, it is important to In a workpiece that has been ground, there may be a part of the circumference that has been ground flat.

This part sometimes suffers from grinding burns. Additionally, many flat or wavy marks may appear on the circumference of the workpiece, and if you look at these marks, you may find that grinding burns have also occurred. As mentioned above, it is extremely rare for a part of a circular workpiece to be ground flat, resulting in grinding or scratches, but it can have a fatal impact on the performance of the product.
For example, if a flat portion occurs on the outer circumferential surface during grinding of a bearing ring, it is a defective bearing ring and must be removed, and the occurrence of such defective products should be completely eliminated.

On the other hand, efficiency is in the process of being pushed to its limits, and as that happens, the frequency of its occurrence is bound to increase. A method was devised to limit the grinding resistance during grinding in order to prevent the above-mentioned defects from occurring in the workpiece, but this method does not affect the delicate contact between the workpiece and the shoe. In order to prevent the occurrence of the above-mentioned defects, there is a drawback that the purpose of prevention cannot be fully achieved unless the grinding resistance is extremely reduced. This invention was made to eliminate the above-mentioned drawbacks, and detects the magnitude of the friction coefficient between the workpiece and shoe during grinding, and determines whether the magnitude of this friction coefficient corresponds to a preset friction coefficient value. This is a method and apparatus for controlling a grinding machine in which a signal is issued when the limit is exceeded, and the grinding feed speed or grinding force is controlled by this signal.

Next, a first embodiment of the present invention will be described.

In the figure, 1 is a grindstone for grinding the workpiece 2, 3 is a shoe holder, a front shoe 4 and a rear shoe 5 are attached to the shoe holder 3, and a shoe tip 6 is attached to the front shoe 4 to grind the workpiece 2. A shoe tip 8 is attached to the rear shoe 5 via a force transducing element 7.The force transducing element 7 detects the force applied to the shoe via the shoe tip. ~〇-Docell, strain gauge, gauge using magnetostriction, etc. are used as detectors for this purpose. In this example, a Shoden type load cell is used, but this piezoelectric type load cell can detect force in three directions. In order to convert the electric charge corresponding to the magnitude of the tangential force and normal force captured by this Shoden type load cell T into voltage, it is possible to A charge amplifier 9 and a charge amplifier 10 are provided, and an lj set circuit 11 for transmitting an lj set signal to each charge amplifier is connected. An amplifier 14715 for amplification is connected, and an arithmetic circuit 16 for dividing a signal based on the magnitude of the tangential force by a signal based on the magnitude of the normal force is connected to this amplifier. In addition, a set voltage circuit 17 is provided which sets a predetermined magnitude of the friction coefficient in consideration of the material of the shoe chip, the material of the workpiece, the grinding speed, etc., and this set value and the signal value from the calculation circuit 16 are used. A comparison circuit 18 is a circuit for comparison.
19 is a V-less motor for driving the grinding wheel head 20;
1 is a pulse oscillator for sending an output signal to the pulse oscillator 19, and 22 is an output gate circuit for controlling the output signal from the pulse oscillator 21, which is connected to receive the signal from the comparison circuit 8. ing.

23 is a feed screw rotated by the pulse motor 19;
4 is a female screw mechanism that screws into the feed screw 23 and the grindstone head 201
This is installed.

25 is a grinding speed setting device.

In this device, when the workpiece 2 is set on the shoe tips 6 and 8, a reset signal is transmitted from the reset circuit 11 to each charge amplifier 9 and 101, and the workpiece 2, which is rotated by a drive shaft (not shown), is placed on the grindstone. When the grinding wheel 1 starts grinding as the table 29 approaches, the tangential force detected by the load cell 7 via the shoe chip 8 is converted into voltage by the charge amplifier 9, and the voltage that has passed through the low-pass filter 12 is amplified by the amplifier 12. and enters the arithmetic circuit 16.

On the other hand, the normal force detected by the load cell 7 is converted into a voltage by a charge amplifier 0, passes through a low-pass filter 13, is amplified by an amplifier 5, and then enters an arithmetic circuit 16, where division is performed. Further, in the comparison circuit 18, the friction coefficient value is compared with a preset friction coefficient value from the set voltage circuit 17. If the signal input to the comparison circuit 18 is smaller than the dust coefficient value input from the set voltage circuit 17, that is, if the workpiece 2 has a friction coefficient value of normal rotation as shown in FIG. The pulse motor 19 is driven by the pulse from the pulse oscillator 2 tatami, and the grinding wheel head 20' advances at a constant speed set by the grinding speed setting device 25, and grinding continues.However, the shoe and workpiece Under conditions such as poor contact with the outer peripheral surface of the shoe and the workpiece, high speed of the workpiece, and grinding with a high paddy filling speed, local seizure may occur between the shoe and the workpiece.
If the coefficient of friction between the shoe and the workpiece exceeds a certain value, an abnormal rotational speed may occur, or if the contact between the shoe and the workpiece is good and the rotational speed of the workpiece is relatively low, the magnetizing force of the driving plate may be reduced. Under conditions such as grinding with a weak and fast cutting speed, abnormal rotational speed (high-speed rotation) of the workpiece may occur, resulting in an increase in the friction coefficient and an abnormal rotational speed. In connection with
When the friction coefficient increases rapidly (see Figure 3) and exceeds the friction coefficient set value, a signal is output from the comparator circuit 18, and the signal is transmitted to the output gate circuit 22, which is closed and the pulse oscillator The pulse signal from 21 is interrupted, the pulse motor 19 is stopped, the rotation of the feed screw 23 is stopped, the grinding feed speed of the grindstone head 20 becomes zero, and the grinding feed is interrupted.

Due to this interruption, the grinding force is sharply reduced, so that the workpiece is prevented from sticking to the shoe. Next, a backward signal is output from the gate circuit 22, and the circuit direction of the pulse motor 19 becomes opposite to that in the case of grinding feed, and as the feed screw 23 reverses, the grindstone head 20 is moved backward via the female screw mechanism 24. . The second embodiment shown below is for a case where the grinding feed is temporarily interrupted due to a sudden increase in the friction coefficient, and then when the friction coefficient falls below the set value, grinding is performed again at a speed slower than the initial grinding feed speed, and the grinding feed is adjusted. In addition to the output gate circuit, a switching circuit 26 is provided between the comparator circuit 18 of the first embodiment and the pulse oscillator 21 as a circuit for use. Illustrations of load cells and the like for detecting the coefficient of friction are omitted.

In this embodiment as well, as in the first embodiment, the normal force and tangential force detected by the load cell are calculated and compared with a set voltage in the comparator circuit 18. If the friction coefficient value between the workpiece and the shoe is smaller than the set value (see Fig. 5), the pulse motor 19 is driven by the pulse from the pulse oscillator 21, and grinding is performed at a constant speed, but the workpiece When an abnormal rotation speed occurs and the friction coefficient value exceeds the set value, an output signal from the comparator circuit 18 enters the output gate circuit 22, the output gate circuit 22 is closed, and the pulse motor 1
9 stops, the grinding wheel head also stops, and the grinding speed decreases from the set speed 1 to zero as shown in FIG.

Feed is interrupted and the friction coefficient value begins to decrease and falls below the set value (
(See FIG. 5), the signal transmission from the comparator circuit 18 is stopped (see FIG. 6), the output gate circuit 22 is opened, and the pulse oscillator 21 is in a state where it can pass pulses.
At this time, the switching circuit 26 sends to the pulse oscillator 21 a command for a set grinding speed 2 (see FIG. 4), which is slightly slower than the set grinding speed 1 at which the workpiece caused the rotational speed abnormality. Therefore, the pulse oscillation is performed from the pulse oscillator 21 a little more than before the abnormality was detected, and grinding feed is started again, but the speed is slower than the set grinding speed 1, and if grinding is performed in this state, , Grinding is completed with almost no abnormality in the rotational speed of the workpiece. However, if an abnormality in the rotational speed of the workpiece occurs, a signal is sent from the comparator circuit 18 to the output gate circuit 22 again, and the output gate circuit 22 is closed to prevent the workpiece from being attached to the shoe. In the third embodiment shown below, during grinding with normal grinding force, an abnormality in the rotational speed of the workpiece was detected by detecting a sudden increase in the friction coefficient, and the grinding feed was temporarily interrupted and the friction coefficient value fell below the set value. When,
In the case where the grinding is performed again with a grinding force that is 4 mm lower than the initially set normal grinding force, the configuration up to the comparison circuit 18 for extracting the friction coefficient is the same as in the above two embodiments.

In FIG. 7, 27 is a switching circuit for changing the grinding force, 28 is a control circuit for keeping the grinding force constant, and 29 is a memory circuit, which together with the output gate circuit 22 constitutes a grinding feed adjustment circuit. . 30 is an indicator for notifying the necessity of reducing the set grinding force.

In this example, grinding is initially performed with the set grinding force, but
If an abnormal rotation speed occurs in the workpiece during grinding with this grinding force, this is detected by a sudden increase in the friction coefficient, and the comparison circuit 18
The output gate circuit 22 is closed by this signal, the pulse from the pulse oscillator 21 is cut off, the pulse motor 19 is temporarily stopped, the grinding feed becomes zero, and the grinding force is reduced. Then, the friction coefficient value is less than the set value (t2 in Fig. 9).
At the same time the signal from the comparator 18 becomes the first
As shown in FIG. 0, the state changes from ON to OFF, the output gate circuit 22 opens, and pulse transmission to the pulse motor 9 becomes possible. The grinding force at this moment (time t2) is stored in the memory circuit 29. (This grinding force is referred to as an adjusted grinding force.) At the same time, in the switching circuit 27, cutting is performed on the adjusted grinding force. As can be seen from FIG. 8, the above-mentioned adjusted grinding force is a grinding force smaller than the set grinding force, and a signal is sent to the pulse oscillator 211 via the control circuit 28, and the pulse oscillator 21 generates a pulse oscillation as the adjusted grinding force. is performed, the pulse motor 19 is driven, and the grinding feed is started again via the feed screw "female screw mechanism", and thereafter grinding is continued with the adjusted grinding force.

If the grinding is completed in this state, the pulse motor 9 will rotate in the reverse direction and the workpiece will be taken out next. However, if the rotational speed abnormality occurs again in the workpiece during grinding with the above adjusted grinding force,
The signal from the comparison circuit 18 enters the gate circuit 22 again, the gate circuit 22 is closed, and the pulse motor 19 is stopped.
Grinding feed is stopped. Further, in this device, at the above-mentioned time t2, the comparator circuit 18 inputs a signal indicating the need for correction of the set grinding force. In other words, since the abnormality in the rotational speed of the workpiece is caused by the inappropriate initial setting of the grinding force, there is a possibility that it will occur again in the next cycle. Therefore, in the next cycle, the set grinding force is slightly lowered to prevent abnormal rotation speed of the workpiece. In the above embodiments, the drive mechanism is a feed screw mechanism using a pulse motor as the drive source, but a hydraulic cylinder is used as the drive mechanism, and the amount of oil supplied to it is adjusted to feed the grinding. It is also possible to adjust.

According to the device of the present invention, it is possible to completely prevent scratches on the shoes due to abnormal rotational speed of the workpiece and bran build-up due to heat generation of the workpiece itself, and increase the grinding speed to achieve efficient grinding. As described above, deterioration in the quality of the outer circumferential surface of the workpiece itself due to abnormal rotational speed can be reliably prevented.
It also has useful features such as preventing the shoe from seizing, thereby helping to maintain a normal lifespan of the shoe.

[Brief Description of the Drawings] Figures 1 and 2 each show an embodiment of the present invention, with Figure 1 schematically showing the workpiece support mechanism and grindstone head, and the control circuit shown in a block diagram. The schematic diagram of the first embodiment shown in FIG. The figure is a line diagram showing the change in the coefficient of friction between the workpiece and the shoe from the time the workpiece is set in the shoe until the completion of grinding. Figures 4 to 6 are lines related to the second embodiment. In the figures, Fig. 4 is a grinding speed diagram, Fig. 5 is a diagram showing changes in friction coefficient, Fig. 6 is a diagram showing output signals in the comparison circuit, and Fig. 7 and the following are diagrams showing the third aspect of this invention. An example is shown, and the control circuit is shown in a block diagram.
9 is a diagram showing changes in grinding force, FIG. 9 is a diagram showing changes in friction coefficient, and FIG. 10 is a diagram showing output signals from the comparison circuit. Explanation of symbols 1. ．． ．． Grinding wheel, 2... Workpiece, 4... Front shoe, 5... Rear shoe, 7... Force conversion element, 9,
10... Charge amplifier, 11... Reset circuit, 16
... Arithmetic circuit, 17... Setting voltage circuit, 18...
Comparison circuit "19...Pulse motor, 21...Pulse oscillator, 22...Output gate circuit, 23...Feed screw,
24...Female thread mechanism, 26...Switching circuit, 27...
-Switching circuit, 28...control circuit, 29...memory circuit. Figure 1 Multiple tickets 3 Figure Tsutomu 4 tickets 5 Figures 6 Figures 7 Figure 8 Tsutomu q Figure Tsutomu '0 Figure

Claims (1)

[Scope of Claims] 1. In a shoe-type centerless grinding machine equipped with a driving plate that rotates the workpiece by contacting one end surface of the workpiece, and a shoe that supports the outer circumferential surface of the workpiece, the grinding machine is used for grinding a workpiece. Detect the normal force and tangential force acting on the shoe at A method for controlling a grinding machine, characterized in that the grinding machine is detected by comparing a friction coefficient value set in advance with a preset friction coefficient value, and the grinding feed is adjusted based on this detection signal. 2 In a shoe-type centerless grinding machine equipped with a driving plate that rotates the workpiece by contacting one end surface of the workpiece, and a shoe that supports the outer peripheral surface of the workpiece, the normal force and tangential force that act on the shoe A force transducer element for detecting the magnitude of the force transducer, a preamplifier provided individually to convert each signal from the force transducer element into a voltage signal, and a reset signal sent to each preamplifier. a reset circuit for dividing the signal based on the magnitude of the tangential force by a signal based on the magnitude of the normal force, and a set voltage circuit for presetting the magnitude of the friction coefficient. , a comparison circuit that compares the setting signal of the setting voltage circuit and the signal from the arithmetic circuit, a grinding feed adjustment circuit that operates based on the signal from the comparison circuit, and a drive that operates using the signal from the grinding feed adjustment circuit. A control device for a grinding machine equipped with a mechanism.