JPS6231244Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the wear limit of a dressing tool for modifying a grinding wheel.

In general grinding machines, dressing of the grinding wheel is performed using a dressing tool with a diamond attached to the tip, but even if diamond is used, the tip of the dressing tool gradually wears out due to dressing of the grinding wheel. However, in the end, the grinding wheel cannot be dressed to a predetermined accuracy, and the workpiece cannot be finished to the desired surface accuracy. For this reason, in the past, the state of diamond wear was periodically visually inspected and the dressing tool was replaced when the amount of wear exceeded a predetermined value. Not only is it necessary to do this, but it is also difficult to accurately measure the degree of wear, which makes inspection work troublesome.

In view of these conventional problems, the present invention corrects the original position of the grinding wheel by advancing the grinding wheel by the depth of cut during dressing every time the dressing of the grinding wheel is performed. It detects the actual amount of movement of the grinding wheel from when the workpiece is ground to the predetermined size until a signal is sent from the sizing device, and when the dressing tool is not worn, the workpiece is ground to the predetermined size from the original position. This method attempts to solve the conventional problems by detecting the wear limit of the dressing tool by comparing the theoretical movement amount of the grinding wheel and the actual movement amount of the grinding wheel until grinding. Examples will be described based on the drawings.

In Fig. 1, 10 is a grinding machine, and this grinding machine 1
A headstock 14 and a tailstock 15 are placed on the bed 11 of the machine 0 via a table 12, and the headstock 1
The center 17 of the main spindle 16 and the tailstock 1 mounted on the shaft 4
A cylindrical workpiece W is held between the tailstock center 18 and a tailstock center 18 which is mounted on a shaft of the main shaft motor 19, and the workpiece W is rotated by the rotation of the main shaft 16 driven by the main shaft motor 19. Reference numeral 20 indicates a sizing device installed on the table 12, which outputs a sizing signal AS1 when the workpiece W reaches the size for which rough grinding has been completed, and
When the dimension reaches the finished dimension, the sizing signal AS2 is output.

In addition, a drive motor 2 is installed at the rear of the bed 11.
A grindstone head 23 supporting a grinding wheel 22 rotated by a grinding wheel 22 is guided so as to be movable forward and backward toward a center axis, and is connected to an output shaft of a pulse motor 24 via a feed screw (not shown). Further, a base 27 of a dressing device 26 is fixed to the side surface of the grinding wheel 22 of the grinding wheel head 23, and a movable base 30 that supports a dressing ram 29 having a dressing tool 28 attached to its tip is mounted on the base 27. Grinding wheel 2
It is guided so as to be movable in the direction of the axis of the second axis. Then, the drum 29 is moved toward the center of the grinding wheel 22 by a pulse motor 31 fixed to the movable table 30, and the movable table 30 is moved in the direction of the rotation axis of the grinding wheel 22 by a cylinder 32 fixed to the base 27. It is designed to move back and forth.

On the other hand, numeral 40 indicates a numerical control device that distributes pulses to drive circuits 41 and 42 that drive the pulse motors 24 and 31 to control the machining of the workpiece W and the depth of cut during dressing. This numerical control device 40
When the grinding command signal GCS is given, the drive circuit 41 sends a number of negative pulses at a rapid traverse speed according to the rapid traverse advance amount Df set in the digital switch DS1.
The amount of rapid forward movement of the grinding wheel 22 from the original position
After advancing by Df, pulses are distributed to the drive circuit 41 at a rough grinding speed until the sizing signal AS1 is sent from the sizing device 20, and when the sizing signal AS1 is sent, the speed of pulse distribution is finely adjusted. The speed is reduced according to the grinding, and when the sizing signal AS2 is sent out, the distribution of pulses is stopped. Then, after this, the grinding wheel 22
The grinding wheel 22 is moved back to the original position by distributing the same number of positive pulses as the negative pulses distributed until the grinding wheel 22 is moved to the forward end position at a rapid feed speed.

On the other hand, a dress command signal is sent to the numerical control device 40.
When DCS is given, the numerical control device 40 sets a constant depth of cut d set in the digital switch DS3.
The number of negative pulses corresponding to Dressing the grinding wheel 22. At the same time, the depth of cut d
distribute a number of negative pulses to the drive circuit 41 according to
The grinding wheel 22 is moved toward the spindle axis by a certain depth of cut d, and the original position is corrected according to the depth of cut of the dressing tool 28. Therefore,
The numerical control device 40 operates as a position correction means for correcting the position of the grinding wheel 22.

Therefore, if the dressing tool 28 is not worn, the position of the grinding wheel 22 at its original position is changed to the main axis by the depth of cut d of the dressing tool 28 each time dressing is performed, as shown in FIG. The grinding wheel 22 is moved to the side so that the position of the grinding wheel processing surface is kept constant, and the amount of advance of the grinding wheel 22 is always constant until the sizing signal AS2 is sent out. however,
In reality, the dressing tool 28 gradually wears out.
The diameter of the grinding wheel after dressing gradually increases depending on the amount of wear on the dressing tool 28, and the position of the grinding wheel machining surface shifts toward the main axis. Therefore, if the above correction is performed, the amount of advance of the grinding wheel 22 immediately after dressing will be reduced. As shown in FIG. 3, when the workpiece W has moved forward by a distance smaller than the theoretical travel amount Xt by the wear amount W of the dressing tool 28, the workpiece W is ground to the finished dimension and the sizing signal is sent from the sizing device 20.
AS2 will be sent.

In FIG. 1, a movement amount counter 50, a deviation calculation circuit 51, a comparison circuit 52, setters 53, 54,
A circuit 45 composed of a gate G1 and a one-shot circuit 55 receives a sizing signal from the sizing device 20.
This is a wear detection circuit that detects when the wear of the dressing tool 28 has reached its limit due to the amount of movement of the grinding wheel 22 until AS2 is sent out. The amount of advance of the grinding wheel 23 immediately after dressing without cutting is set as the theoretical value Xt, and the allowable wear amount W of the dressing tool 28 is set in the wear amount setting device 54.

Now, when the grinding command signal GCS is given to the numerical control device 40 and the grinding wheel 22 starts to be fast-forwarded, a signal of a certain time width is output from the one-shot circuit 55 and the movement amount counter 50 is reset. After this, the negative pulses output to the drive circuit 41 are counted by the movement amount counter 50 and the grinding wheel 2 is moved forward.
The amount of movement of the grinding wheel 22 is detected. The workpiece W is machined to a finishing size by the advancement of the grinding wheel 22.
When the size signal AS2 is output from 0, the gate G1
The counter 50 is opened and the count value of the movement amount counter 50 is given to a deviation calculation circuit 51 as the forward movement amount X of the grinding wheel 22.
The deviation between the advance movement amount X of the dressing tool 22 and the theoretical movement amount Xt set in the setting device 53 is calculated. This deviation is equal to the wear amount W of the dressing tool 28 as described above, and when this deviation exceeds the allowable wear amount W set in the setting device 54, the comparison circuit 52 outputs a wear detection signal.
The WDS is output, and an unillustrated alarm lamp or the like is turned on to notify the operator that the dressing tool 28 has reached its wear limit.

FIG. 4 shows another embodiment of the wear detection circuit 45, in which when the grinding command signal GCS is given, the theoretical distance from the grinding wheel machining surface to the center axis at the original position set in the setting device 66 is The data of Ro is loaded into the position counter 61, and then the loaded value is subtracted by a negative pulse distributed to the drive circuit 41. When the sizing signal AS2 is sent, the gate G1 is opened and the value of the position counter 60 is given to the deviation calculation circuit 61, and the deviation between the contents of the position counter 60 and the setting value set in the setting device 63 is calculated. Calculate. The finishing radius Rf of the workpiece W is set in the setting device 63, and the finishing radius Rf of the workpiece W is set in the setting device 63, so that the grinding wheel 2
The deviation from the logical value Xt of the amount of movement forward by 2 is output. As in the case described above, this deviation represents the amount of wear w of the dressing tool 28,
When this exceeds the allowable wear amount W, the comparison circuit 62 outputs a wear detection signal WDS.

In the above embodiment, the wear amount of the dressing tool was detected based on the change in the amount of movement of the grinding wheel until the fine grinding completion signal AS2 was sent from the sizing device. The wear of the dressing tool may be detected based on the change in the amount of movement until the rough polishing completion signal AS1 is sent from the device.

Further, in the above embodiment, the present invention is applied to a grinding machine in which the original position of the grinding wheel 22 is corrected every time dressing is performed to compensate for a decrease in the grinding wheel diameter. If the amount of advance of the grinding wheel is detected based on the position of .

As described above, in the present invention, each time the grinding wheel is dressed, the grinding wheel is advanced by the depth of cut during dressing to correct the original position of the grinding wheel, and the work is performed from this corrected original position. The actual amount of movement of the grinding wheel until the object is ground to a predetermined size and a signal is sent from the sizing device is detected, and this detected amount of movement assumes that there is no wear on the dressing tool. This method detects how much smaller the amount of travel is compared to the theoretical amount of travel, and determines that the dressing tool has reached its wear limit when the amount of decrease in travel exceeds the allowable value. , it is possible to automatically and highly accurately determine when the wear of the dressing tool has reached its limit, and not only does it not require periodic inspection of the wear condition of the dressing tool, but also by sending out a determination signal. If the next machining cycle is prevented from starting, the workpiece will not be machined by the grinding wheel that has been dressed by the dressing tool that has reached its wear limit, and the workpiece with poor surface accuracy will be transferred to the next process. It also has the advantage of preventing water from flowing into the water.

In addition, in the present invention, the amount of movement of the grinding wheel from the original position where the grinding surface of the grinding wheel is in a fixed position until the workpiece is ground to a predetermined size and a signal is sent from the sizing device. Since the amount of wear on the dressing tool is detected based on the change, wear on the dressing tool can be detected during the normal grinding process using sizing signals, and a special grinding cycle is required to detect wear on the dressing tool. This method not only simplifies the control circuit but also allows workpieces to be machined to regular dimensions.

Furthermore, as a sizing device, you can use a normal sizing device that outputs a signal when the workpiece size reaches the set size, without using a special sizing device that can output workpiece size data. There are good advantages.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic plan view of a grinding machine with an electric circuit, and Fig. 2 is a drawing in which it was thought that the dressing tool 28 shown in Fig. 1 would not wear out. FIG. 3 is a diagram showing the change in the position of the grinding wheel 22 between its original position and the forward end when the dressing tool 28 is worn, and FIG. is the first
FIG. 4 is an electrical circuit diagram showing a second embodiment of the wear detection circuit 45 shown in the figure. 10...Grinding machine, 20...Sizing device, 22...
Grinding wheel, 23... Grinding wheel head, 24... Pulse motor, 28... Dressing tool, 29... Dressing ram, 31... Pulse motor, 32... Cylinder, 40... Numerical control device, 45... Wear detection circuit , 50... Movement amount counter, 60... Position counter, 51, 61... Deviation calculation circuit, 52, 62
...Comparison circuit.

Claims (1)

[Scope of utility model registration request] The grinding wheel positioned at the original position a predetermined distance from the spindle axis is moved forward, and when the workpiece is ground to the predetermined dimensions and a signal is output from the sizing device, the grinding wheel is moved back and machined. In a grinding machine that processes objects and dresses the grinding wheel by giving a constant relative depth of cut to the dressing tool of the dressing device installed on the grinding wheel head,
Position correction means for correcting the original position of the grinding wheel by moving the grinding wheel toward the spindle axis side by a certain amount of relative cutting of the dressing tool during dressing each time the grinding wheel is dressed. and a movement amount setting device for setting a theoretical movement amount that the grinding wheel head should move before starting movement from the original position and grinding the workpiece to a predetermined dimension, assuming that the dressing tool is not worn. The actual movement amount and the theoretical movement set in the movement amount setter after the grinding wheel starts moving from the original position, the workpiece is ground to the predetermined size, and the signal is output from the sizing device. a wear amount setter that sets the amount of wear of the dressing tool until the wear limit is reached; and a wear amount setter that sets the deviation detected by the deviation detection means to the wear amount setter. 1. A wear limit detection device for a dressing tool, comprising: a determination means for detecting whether or not the wear amount exceeds a specified wear amount and outputting a signal.