JPH0220378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a tool abnormality detection device for detecting abnormalities in a tool on a rotating spindle supported by a spindle head.

<Prior art> For example, when machining is performed using a rotating tool such as a milling cutter, the multiple cutting edges do not wear uniformly, so the internal portion of the multiple cutting blades that has a large amount of wear may be involved in the machining. When the load torque is at its maximum, the load torque is the largest, and when detecting the tool wear condition based on the load torque, it is necessary to determine the tool wear condition based on the magnitude of the peak value of the load torque.

However, since the timing of the peak occurrence of this load torque is not constant, it is not possible to use a microcomputer that samples this load torque at regular intervals and sends out an abnormal signal when it exceeds a set value. There is no guarantee that the computer is always sampling the peak value,
There was a problem where reliable detection could not be performed.

<Purpose of the Invention> Therefore, an object of the present invention is to make it possible to determine the wear state of a tool by reliably capturing changes in the peak value of load torque, and to accurately determine abnormalities in the tool. It is something.

<Configuration of the Invention> FIG. 1 is an overall configuration diagram for clearly explaining the present invention. The load torque acting on the main shaft 12 is detected by a torque detection means 16, and the output of this torque detection means 16 is supplied to a peak value detection circuit 21. The output of the peak value detection circuit 21 is sampled and held in synchronization with the fall of a pulse signal output from a pulse generating means 18 that generates a pulse every time the spindle 12 rotates once. The peak value detection circuit 21 is then reset in synchronization with the rise of the pulse signal. As a result, the sample hold circuit 22 outputs a signal representing a change in the maximum peak that occurs during one rotation of the main shaft among the peak values of the torque signal output from the torque detection means 16.
When the output of the peak value detection circuit 21 exceeds the reference value by more than a permissible value, the computer 26 outputs an abnormality signal.

<Examples> Examples of the present invention will be described below based on the drawings. In FIG. 2, 10 is a headstock moved by a servo motor 11 for feeding, and this headstock 10 has a main spindle 1 with a tool T attached to its tip.
2 is supported on a shaft and rotated by a main shaft motor 13.

The servo motor 11 is driven by a drive circuit 15 operated by a command pulse from a numerical control device (not shown), and its drive current is detected by a current detector 16. The output of the converter 16 is converted into a voltage signal by a current-voltage converter 19. As a result, the current voltage converter 19
A voltage signal representing the magnitude of the load torque acting on the servo motor 111 is output from the servo motor 111 . The headstock 10 also includes a rotating disk 1 attached to the spindle 12.
Proximity switch 18 operated by a dog on 7
is attached, and outputs a pulse-like signal shown in FIG. 3b every time the main shaft 12 rotates once.

On the other hand, 20 is a detection circuit that detects changes in the peak value of the torque signal output from the current-voltage converter 19 in synchronization with the rotation of the main shaft 12, and is connected to the output of the current-voltage converter 19 for detecting peak values. circuit 2
1. A sample hold circuit 22 which samples and stores the output of this peak value detection circuit 21, which detects the rise and fall of the pulse signal output from the proximity switch 18, respectively, as shown in FIG. 3c and d. The sample and hold circuit 22 is activated by the output of the rise detection circuit 23, and the output of the fall detection circuit 24 is activated by the output of the rise detection circuit 23. Therefore, the peak value detection circuit 21
The memory contents are reset.

Therefore, each time the main shaft 12 makes one revolution and enters a predetermined phase state and a pulse signal is output from the proximity switch 18, the peak value of the load torque within one revolution of the main shaft detected by the peak value detection circuit 21 is detected by the peak value detection circuit 21. is transferred to the sample hold circuit 22 in synchronization with the rise of the pulse signal, and thereafter the peak value detection circuit 21 is reset at the fall of the pulse signal. As a result, the sample hold circuit 22
As shown as a' in Fig. 3a, the maximum peak value of the load torque that occurs during one revolution of the main shaft 12 is output, and this is updated every time the main shaft 12 makes one revolution. become.

The output of this sample and hold circuit 22 is then supplied to the input terminal of the AD converter 25.
The output of the AD converter 25 is connected to a microprocessor 26 which together with a memory 27 constitutes a microcomputer.

The microprocessor 26 is supplied with an interrupt signal from the interrupt signal generation circuit 28 in synchronization with the fall of the pulse signal output from the proximity switch 18. The processing shown in FIG. 4 is performed in response to the supply of the input signal. When this process starts, first step 30
A start signal is given to the AD converter 25 in step 31, and after waiting for a certain period of time in step 32,
Read the output of AD converter 25. Subsequently, in step 33, the master value Man measured and stored during trial machining is read out from the memory 27, and in step 35, the master value Man is read out from the measured value.
is subtracted to calculate the deviation between the two, and it is determined in step 36 whether or not this deviation is a positive value exceeding the allowable value. As a result, if it is determined that the tolerance is exceeded, the process moves to step 37, where the abnormality signal ABN is sent and abnormality display processing is performed.
If it is determined that the permissible value has not been exceeded, the process returns to the main routine (not shown) without performing any processing.

In the above operation, the sample hold circuit 2
Since the sample operation in step 2 and the reset operation of the peak value detection circuit 21 are performed in synchronization with the rotation of the spindle 12, when the rotation speed of the spindle 12 is changed due to a change in the tool T, the rotation speed of the spindle 12 is changed accordingly. The speed of sample operation and reset operation also changes. Therefore, even if the maximum peak value generation interval becomes longer as the rotational speed of the main shaft 12 decreases, there is no possibility that a peak occurring in a portion where there is no maximum peak will be mistakenly detected as the maximum peak. Furthermore, the faster the spindle 12 rotates, the more likely the tool will break due to an increase in load torque, so it is necessary to detect an increase in load torque without delay in response. The faster the spindle 12 rotates, the faster the response speed becomes, and the detection speed can be increased.

In the above embodiment, the load torque is detected by the motor drive current for feeding the headstock 10, but the load torque may be detected by the drive current of the spindle motor 13.

<Effects of the Invention> As described above, in the present invention, the peak value detection circuit connected to the torque detection means, the sample hold circuit that samples and stores the output of this peak value detection circuit, and the pulse generating means for generating a pulse each time the main shaft rotates at least once; and a control means for resetting the peak value detection circuit after activating the sample hold circuit in response to a signal from the pulse generating means. Since the sample and hold circuit output exceeds the reference value, an abnormal signal is output, allowing accurate detection of the change in the maximum peak of the load torque, which correctly represents the wear of the inner cutting tool. This has the advantage of being able to determine the state of tool wear, etc., and accurately determining tool abnormalities.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram for clearly demonstrating the present invention.
2 to 4 show embodiments of the present invention,
2 is a block diagram showing the overall configuration of the tool abnormality detection device, FIG. 3 is a time chart showing the operation of the detection circuit 20 in FIG. 2, and FIG. 4 is a diagram showing the operation of the microprocessor 26 in FIG. 2. It is a flowchart. 10... Headstock, 11... Servo motor, 12
... Main shaft, 16 ... Torque detection means, 18 ... Proximity switch, 21 ... Peak value detection circuit, 22 ...
...Sample hold circuit, 23...Rise detection circuit, 24...Fall detection circuit, 25...AD converter, 26...Microprocessor, 27...Memory, 28...Interrupt signal generation circuit, T... …tool.

Claims (1)

[Claims] 1 A tool abnormality detection device for detecting an abnormality in a tool on a rotating spindle supported by a spindle head, and a torque detection means for detecting the driving torque of a feed motor that relatively displaces the spindle head or the spindle drive motor. a peak value detection circuit connected to the torque detection means; a sample hold circuit that samples and stores the output of the peak value detection circuit;
pulse generating means that generates a pulse every time the main shaft rotates at least once in synchronization with the rotation of the main shaft; and after activating the sample and hold circuit in response to a signal from the pulse generating means, detecting the peak value. It is characterized by comprising a control means for resetting the circuit, and a computer that operates in response to a signal from the pulse generation means and outputs an abnormal signal when the output of the sample and hold circuit exceeds a permissible value. Tool abnormality detection device.