JPS603553B2 - Grinding machine control method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shoe-type centerless grinding machine, and to a control method and device for adjusting the grinding feed according to the magnitude of the tangential force acting on the shoe of a workpiece. .

Shoe-type centerless grinding machine, in other words, the two shoes level the workpiece in the vertical direction, and the driving plate determines the position in all directions, and at the same time this gives rotation to the workpiece, separating the workpiece and the driving plate. For example, in a shoe-type centerless grinding machine, which uses a magnet, it is necessary to make the parts in close contact with each other when producing a large number of circular workpieces on a production line, especially when producing at high efficiency. Among the produced workpieces, there may be a part of the circumference that has been ground flat.

This part sometimes suffers from grinding burns. In addition, many flat or wavy marks may appear on the upper surface 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. In order to prevent the occurrence of the above-mentioned defects, there was a drawback that the purpose of prevention could not be fully achieved unless the grinding resistance was extremely reduced.This invention aims to eliminate the above-mentioned drawbacks. It detects the magnitude of the tangential force acting on the shoe of the workpiece during grinding, and a signal is generated when the detected tangential force exceeds a preset tangential force magnitude. The present invention provides a method and apparatus for controlling a grinding machine that controls the grinding feed, that is, the grinding feed rate or the grinding force using this signal.

Next, a first embodiment of the present invention will be described. In the figure, 1 is a grindstone for grinding a workpiece 2, 3 is a shoe holder, and this shoe holder 3 has a front shoe 4.
And the rear shoe 6 is attached, and the rear shoe 6 is attached. booklet shoe 4
A shoe tip 6 is provided so as to be in contact with the outer peripheral surface of the workpiece 2, and a shoe tip 8 is attached to the rear shoe 5 via a force transducing element 7. The force transducing element 7 is a detector for detecting the force applied to the shoe via the shoe tip, and may be a load cell, a strain gauge, a gauge using magnetostriction, or the like. In this embodiment, a piezoelectric load cell is used, and this piezoelectric load cell can detect forces in three directions. A charge amplifier 9 is provided as a preamplifier for converting the electric charge corresponding to the magnitude of the tangential force detected by the piezoelectric load cell 7 into a voltage, that is, converting the electric charge into a voltage. A reset circuit IQ for transmitting a reset signal is connected to the charge amplifier 9.
An amplifier 12 for signal amplification is connected to via a low-pass filter 11. On the other hand, in consideration of the material of the shoe chip, the material of the workpiece, the grinding speed, etc., a "setting voltage circuit 3 in which a predetermined magnitude of tangential force is set" is provided, and this setting value and the signal amplified by the amplifier 12 are provided. 15 is a pulse motor for driving the grinding wheel head 16, and 17 is this pulse motor 15.
A pulse oscillator 18 is an output gate circuit for controlling the output signal from the pulse oscillator 17, and is connected to receive the signal from the comparison circuit 14.

19 is a feed screw rotated by the pulse motor 15;
It is attached to the whetstone head 16 by a female screw mechanism that screws into the feed screw turtle 9.

21 is a grinding speed setting device.

In this device, the workpiece 2 is set on the shoe tips 6 and 8, a reset signal is sent from the reset circuit 10 to the charge amplifier 9, and the workpiece 2, which is rotated by a drive shaft (not shown), is placed on the grindstone head 16. When the grinding wheel 1 starts grinding due to the approach of
The voltage passed through is amplified by amplifier 12 and enters comparator circuit 14 .

In this comparison circuit 14, it is compared with a preset tangential force value from a set voltage circuit 13. Comparison circuit 14
If the signal input from the set voltage circuit 13 is 4 mm lower than the tangential force set value input from the set voltage circuit 13, that is, when the workpiece 2 is rotating normally, no signal is emitted from the comparator circuit 14, and the pulse oscillator 1
The pulse motor 15 is driven by the pulse from the grinding speed setting device 21, and the grinding wheel head 16 advances at a constant speed set by the grinding speed setting device 21, and the grinding feed continues. However, under conditions such as grinding where the contact between the shoe and the outer peripheral surface of the workpiece is poor and the workpiece speed is high and the cutting speed is high, a dark local aging phenomenon occurs between the shoe and the workpiece. , Grinding conditions where the tangential force increases and abnormal rotational speed occurs, the contact between the shoe and the workpiece is good, the rotational speed of the workpiece is relatively slow, the magnetizing force of the driving plate is weak, and the cutting speed is high. In some cases, an abnormal rotational speed (high-speed rotation) of the workpiece occurs, resulting in an increase in tangential force, leading to an abnormal rotational speed. However, when the tangential force setting value is exceeded, the comparator circuit 14
A signal is output, the signal is transmitted to the output gate circuit 18, the output gate circuit 18 is closed, the pulse signal from the pulse oscillator 17 is interrupted, the pulse motor 15 is stopped, and the rotation of the feed screw 19 is stopped. , the grinding feed speed of the grindstone head 16 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 18, the rotational direction of the pulse motor 15 is reversed to that in the case of grinding feed, and the feed screw 19 is reversed, so that the grindstone head 16 is moved backward via the female screw mechanism 20. . The second embodiment shown below is a case where the grinding feed is temporarily interrupted due to a sudden increase in the tangential force, and then when the tangential force becomes less than the set value, the grinding is performed again at a speed lower than the initial grinding feed speed.
As a grinding feed adjustment circuit, in addition to the output gate circuit, a switching circuit 22 is provided between the comparator circuit 14 of the first embodiment and the pulse oscillator 17. Only a block diagram is shown, and the workpiece support mechanism is , a grindstone head, a load cell for detecting tangential force, etc. are not shown. In this embodiment, as in the first embodiment, the tangential force detected by the load cell is compared with a set voltage in the comparator circuit 14. If the magnitude of the tangential force applied to the shoe by the workpiece is smaller than the set value (see Figure 4), the pulse motor 15 is driven by pulses from the pulse oscillator 17, and grinding is performed at a constant speed. When an abnormal rotation speed occurs in the workpiece and the magnitude of the tangential force exceeds the set value, an output signal from the comparator circuit 14 enters the output gate circuit 18, the output gate circuit 18 is closed, and the pulse motor 16 is stopped. Therefore, the grinding wheel head also stops, and the grinding speed decreases from the set speed 1 to zero as shown in FIG.

When the feeding is interrupted and the magnitude of the tangential force becomes smaller and becomes less than the set value (see Fig. 4), the signal transmission from the comparator circuit 14 stops (see Fig. 5), and the output gate circuit 14 opens. A state is reached in which pulses can be passed from the pulse oscillator 17. At this time, the switching circuit 22 sends a command to the pulse oscillator 17 for a set grinding speed 2 (see FIG. 3), which is a slightly slower speed than the set grinding speed 1 at which the workpiece caused the rotational speed abnormality. Therefore, the pulse oscillator 17 generates pulses a little more than before the abnormality was detected, and grinding feed starts 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 14 to the output gate circuit 18 again, and the output gate circuit 18 is closed to prevent the workpiece from attaching to the shoe. In the third embodiment shown below, abnormal rotation of the workpiece is detected by detecting a sudden increase in tangential force during grinding with normal grinding force, and the grinding feed is temporarily interrupted until the magnitude of the tangential force falls below a set value. When 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 14 is the same as in the above two embodiments in order to extract the magnitude of the tangential force. It is.

In FIG. 6, 23 is a cutting circuit for changing the grinding force, 24 is a control circuit for keeping the grinding force constant, 25 is for detecting a grinding force that does not cause abnormal rotation speed of the workpiece,
A memory circuit 26 for maintaining this grinding force is an indicator for notifying the necessity of reducing the set grinding force. In this embodiment, grinding is initially performed with a 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 tangential force, and the comparison circuit 1
The output gate circuit 18 is closed by the signal from 4, the pulse from the pulse oscillator 17 is cut off, the pulse motor 15 is temporarily stopped, the grinding feed becomes zero, and the grinding force decreases. Then, as soon as the tangential force becomes less than the set value (see time t2 in Fig. 8), the signal from the comparator circuit 14 changes from ON to OFF as shown in Fig. 9, the output gate circuit 18 opens, and the pulse motor It becomes possible to transmit pulses to 15. The grinding force at this moment (time t2) is stored in the memory circuit 25. (This grinding force is called an adjusted grinding force.) At the same time, the switching circuit 23 switches to the adjusted grinding force. As can be seen from FIG. 7, the above adjusted grinding force is smaller than the set grinding force, and the control circuit 24
A signal is sent to the pulse oscillator 17 via the pulse oscillator 17, the pulse oscillator 17 performs pulse oscillation as an adjusted grinding force, the pulse motor 15 is driven, and grinding feed is started again via the feed screw and internal thread mechanism. Thereafter, grinding is continued with the adjusted grinding force.

If the grinding is completed in this state, the pulse motor 15 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,
A signal is again input from the comparison circuit 14 to the gate circuit 18, the gate circuit 18 is closed, the pulse motor 5 is stopped, and the grinding feed is stopped. In addition, in this device, the above-mentioned time t
2, the comparator circuit 14 sends a signal to the display 26 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 almost completely possible to prevent scratches on the shoe due to abnormal rotational speed of the workpiece and burn-out caused by the heat generation of the workpiece itself, and it is possible to increase the grinding speed and perform efficient grinding. This is possible, and the deterioration of the quality of the outer circumferential surface of the workpiece itself due to abnormal rotational speed is almost certainly prevented as described above. In addition, since the shoe is prevented from getting wet, it helps to maintain a normal life of the shoe, and the device itself has useful features such as being relatively simple.

[Brief explanation of the drawing]

1 and 2 each show an embodiment of the present invention. FIG. 1 schematically shows a workpiece support mechanism and a grindstone head, and the control circuit is shown in a block diagram of the first embodiment. The schematic diagram of FIG. 2 shows the second embodiment, the workpiece support mechanism and the grindstone head are omitted, and only the block diagram for control is shown. Figure 3 is a grinding speed diagram, Figure 4 is a diagram showing changes in tangential force, Figure 5 is a diagram showing output signals in the comparison circuit, and Figures 6 and below are diagrams related to the example. shows a third embodiment of the present invention, the control circuit is shown in a block diagram, FIG. 7 is a diagram showing changes in grinding force, and FIG. 8 is a diagram showing changes in tangential force. , FIG. 9 is a diagram showing output signals in the comparator circuit. Explanation of symbols, 1... Grindstone, 2... Workpiece, 4...
Front shoe, 5... Rear shoe, 7... Force conversion element,
9...Charge amplifier, 10...Reset circuit, 13.
... Setting voltage circuit, 14... Comparison circuit, 15... Pulse motor IT... Pulse oscillator, 18... Output gate circuit, 19... Feed screw, 20... Female screw mechanism, 2
2...Switching circuit, 23...Switching circuit, 24...Control circuit, 25...Storage circuit. Tsutomu 1 figure Tsutomu 21 percent pig 6 figure Tsutomu 3 figure customer 4 figure Kayagu figure hair wa figure 8 figure figure q 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. Detects the tangential force acting on the shoe, detects abnormal rotation of the workpiece by comparing the magnitude of the obtained tangential force with the magnitude of the tangential force set in advance, and adjusts the grinding feed based on this detection signal. A method for controlling a grinding machine that is also characterized by: 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 magnitude of the tangential force acting on the shoe is determined. A force transducing element for detection, a preamplifier provided occasionally for converting the signal from the force transducing element into a voltage, a reset circuit for transmitting a reset signal to the preamplifier 12, and a reset circuit for transmitting a reset signal to the preamplifier 12. A set voltage circuit whose size is set in advance, a comparison circuit that compares the setting signal of the set voltage circuit and the signal from the preamplifier, and a grinding feed adjustment circuit that is activated by the signal from the comparison circuit. A control device for a grinding machine that includes a drive mechanism that operates with a signal from a grinding feed adjustment circuit. 3 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 magnitude of the tangential force acting on the shoe is detected. a preamplifier provided for converting a signal from the force transducing element due to tangential force into a voltage signal, and a reset circuit for transmitting a reset signal to the preamplifier;
a set voltage circuit that presets the magnitude of the tangential force; a comparison circuit that compares the setting signal of the set voltage circuit with the signal from the preamplifier; and a gate circuit that is activated by the signal from the comparison circuit; A storage circuit for detecting a grinding force that does not cause rotational speed abnormality on the workpiece based on the signal from the comparison circuit and the signal from the force conversion element, and for maintaining this grinding force, and this storage circuit and the comparison circuit. A control device for a grinding machine, comprising: a connected grinding force switching circuit; a control circuit provided between the switching circuit and the pulse oscillator; and a drive mechanism operated by a signal from the gate circuit.