JPS60127957A - Detection of damage of tool and apparatus thereof - Google Patents

Abstract

PURPOSE:To distinctly judge the damage of a tool by detecting the behavior of the grinding tool itself in the actual grinding and comparing the variation of speed of a rotary member for driving the tool with the passage of time in the actual cutting with the model diagram for the variation and judging the damage of tool according to the result of comparison. CONSTITUTION:In working by an electrical twist drill, etc., a speed detector 3 for detecting each number of revolutions of the output shaft 5 of a motor, spindle shaft 7, or a power transmission part 9 is provided, and said output is input into a comparator 11. The model diagram of the variation of the number of revolutions in the ordinary cutting with the passage of time which is memorized in a memory apparatus 1 and the number of revolutions at each sampling time point are compared. When it is detected that the variation of speed in the actual grinding with the passage of time, with respect to the model diagram, exceeds the upper or the lower limit of an allowable range continuously for a set time T or more, a tool injury signal is transmitted into a controller 13, and a cutting stop instruction or a tool injury alarm is generated from the controller 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cutting tool damage detection method and an apparatus used therefor.

Conventionally, a method of detecting damage to a cutting tool such as an electric drill is a method of detecting the load current of a main motor for driving the drill. Is this tool damage detection method effective for detecting damage to medium-diameter drills? In the case of small-diameter and large-diameter drills, it is difficult to detect drill damage because the degree of change in current is small. C-Sometimes there is a problem.

Recently, a method for detecting damage to small-diameter shellfish using so-called acoustic emission has been put into practical use. However, this detection method cannot detect damage until even 86 trills have broken. There is a problem that it is 4f wide.

This defense was made in view of such conventional problems, and is based on the following: The rotation is directly detected, and the rotation speed of these rotating parts when processed with a normal tool is compared to the rotation speed at the same point in the one-hour model diagram. If the tool is damaged, it can be determined that the tool has been damaged, or the change in the time integral value of the rotation speed can be calculated as the rotation speed of the tool drive rotating member during actual cutting. Tool damage can be accurately detected by comparing it with the time integral value of The purpose of this invention is to provide a detection method and a device used therefor.

In general, when a load is applied to the hoist of an electric drill or other cutting tool, or a load is applied to the tool, the rotational speed of the rotating parts for driving the tool, such as the output shaft of the main motor, the spindle shaft, the rotation transmission part for the cutting tool, etc., decreases. However, if the cutting tool is damaged, its resistance becomes even weaker and the rotational speed further decreases.

This invention grasps the behavior of the cutting tool itself during actual cutting, and calculates the time change in the rotation speed during actual cutting based on a model diagram of the time change in the rotation speed of the rotating member for driving the tool. The tool is characterized in that it is determined that the tool is damaged if the number of revolutions decreases abnormally and continues to decrease for a certain period of time.

A detailed explanation will be given below based on the embodiment shown in the figures. Figure 1 is a graph showing the time change in the rotational frequency of the rotating member for driving the tool during normal machining of a cutting tool such as an electric drill. This becomes a model diagram for time changes.
Explaining the model diagram in the figure, when power is applied to the main motor, the rotation speed decreases to a constant speed of 1 (point A in the figure). After this constant speed rotation reaches j'', cutting of the material to be cut starts (point 13 in the same figure). When cutting starts, the rotation speed of the rotating member decreases due to the load on the cutting tool. (Point C in the same figure).After that, since the load is almost constant, the rotation speed remains constant until the machining is completed (Point C in the same figure).After machining is completed, remove the cutting tool from the workpiece. The rotating member resumes high-speed, constant-speed rotation when the square load is removed (point E in the figure).After that, when the power is cut off, the rotational speed drops to O.This is normal cutting. ]-It is a model diagram of a one-question change in the rotational frequency of the tool rotation axis of the tool.

One embodiment of the first invention provides 1 for such a model diagram.
- Set the allowable range of rotational frequency change below, and use an appropriate rotational speed detection means to measure the time change in the rotational speed of the rotating member of the cutting tool during actual cutting at the corresponding point in time on the model diagram. Compared to the rotation speed, as shown by the broken line in Figure 1, the rotation speed during actual cutting is low and deviates from the lower limit tolerance range ■ at point E, and further deviates from it for more than the set time T until point G. - (If there is, it is determined that there is an abnormality at this G point, and it is detected that there is damage to the cutting tool.

Next, an embodiment of the second invention will be explained with reference to FIG.

The time change in the rotational speed during the lζ model JIG I shown in FIG. 2 is similar to the model diagram shown in FIG. The feature of this embodiment of the second invention is that the tool damage detection is used in cases where the number of revolutions changes rapidly over time and accurate damage to the tool cannot be detected by comparing only the time changes in the number of revolutions. It is a repayment. Compare the time integral value of the rotational speed of the Eri drive shaft during actual cutting with the time integral value of the rotational speed in the model diagram at t4L, and as shown by the broken line in Figure 2, the rotational speed during actual cutting. A platform where the time integral value falls outside the allowable range with respect to the time integral value in the model diagram (Fig. 2 H)
If this condition continues for a set time T or longer (point 8 in the figure), it is determined that there is an abnormality in the tool.

In other words, the permissible limit is exceeded at a point in time H when the actual cutting direction 1-tal rotational speed is dJl for the total rotational speed dJl on the 7JL diagram from a certain initial point, and that is 8 points. If it continues until the end, it is determined that there is a tool loss.

An example of a tool damage detection device used in each of the embodiments of the first and second inventions is shown in FIGS. A model diagram of the change in rotational speed over time during normal machining is stored in the storage device 1 (ii). The rotation speed detection device 3 detects the output shaft of the motor (5) spins 1 to 1llh.
7 or a power transmission section 9 that transmits power to the tool
Detects the rotation of the rotating part for driving tools such as Ill/, etc. Detection of the rotational speed of J3 by this rotational speed detection device 3 is performed moment by moment. The output of the time integral value can be freely switched to -C as required.

The output from this rotational speed detection device δ3 is input to a comparator 11. In the comparison device 11, the rotation speed is compared at each sampling time with a model diagram of the time change of the rotation speed during normal 9) closing stored in the storage device 1, or the rotation speed is compared at each sampling time Then, in this comparison device 11, an upper limit tolerance range ■ or a lower limit tolerance range ■ is set for the time change of the rotation speed during actual cutting with respect to the model diagram as shown in Fig. 1. time T
If deviation is detected continuously during the above period, the output of A is outputted to the control device 13. Further, when the detection device 3 outputs the time integral value of the rotation speed, the storage device 1 also outputs the time integral value of the rotation speed at the corresponding point in the model diagram, and the comparison device 11 compares the time integral value of the rotation speed. As shown in Fig. 2, the time integral value of
If the drop exceeds the capacity range and continues for a set period of time, it is determined that tool damage has occurred and a tool damage signal is issued to the control device 13.

The control device 13 receives the tool damage signal from the comparator 11, issues a cutting stop command, or issues a tool damage alarm if it is an NC control device, and then returns to the zero load state. (Issuing a command to stop the machine).

A display unit 15 is connected to the rotational speed detection device 3, as required, for displaying the detected rotational speed or (, 1) and its time integral value.

A roughly detailed configuration of the rotation speed detection device 3 is shown in FIG. Rotation speed of rotating member for tool drive
A tocoupler 1 converts the pulse signal into a pulse signal.
The frequency signal is manually inputted to the counter 21 via the frequency signal.

This counter 21 is equipped with a sensor 23 such as a limit switch or an optical sensor that detects the processing start point and processing end point.
is connected, and the input from the encoder 17 is set to 1, with the start of machining by this sensor 23 as time 0.
~do. 1 and in this counter 21, the setting jF
(The number of revolutions can be detected by the number of counts every 17 hours, and the integral value of the number of revolutions can be obtained by integrating the number of counts from the zero point.

The rotational speed detection signal from the counter 21 is input to the central processing unit 27 via the interface 25 and is subjected to arithmetic processing. Two random access memories and a read-only memory 31 are connected to the central processing unit 27.

The display unit 15 is also connected via the ink face 33. The rotational speed of the rotating part or its time integral value calculated by the central processing unit 27 is output to the interface 35 to the comparator 11.

The display section 15 is a digital display, and includes a latch memory 37, a decoder driver 39, and a 7 segment display 41, and displays the number of revolutions detected by the detection device 3 or the time integral value of the number of revolutions. Ru.

In addition, in the example a5 of the tool damage detection device which detects tool damage by comparing the time integral value of the rotation speed during actual cutting with the time integral value of the model diagram, there is an upper limit on the time integral value of the rotation speed. It also sets the tolerance range. This is the line indicated by the symbol ■ in Fig. 2, but the reason why this upper limit tolerance range ■ is set is because the rotational speed of the tool increases due to breakage or other reasons during actual cutting. This is to allow constant detection of operations p, y, and q even when the rotational speed is close to the current state.

If an abnormality is detected by the comparison device 11,
Similarly, a tool damage detection signal can be manually inputted to the control device 13 to issue a command such as an emergency stop of the machine or a tool damage alarm.

This invention monitors the rotation speed of the rotating tool drive member when the tool is fully closed, and compares the rotation speed of the drive rotating member when machining with a normal tool with the rotation speed at the same time in a one-hour model diagram. However, if the rotational speed drops abnormally or the time integral value of the rotational speed drops abnormally, and this low 1ζ state continues for more than a set time, this will be detected and the tool will be able to determine if the tool is damaged. Compared to conventional methods, which judge damage to the tool by reading fluctuations in the current value of the motor, damage to the tool can be determined by directly detecting a decrease in the number of turns. It has the advantage of being able to accurately detect tool damage due to its simple structure.

[Brief explanation of the drawing]

Fig. 1 is a model diagram of the number of rotations per hour of the rotating member for driving a tool used in an embodiment of the first invention, and Fig. 2 is a model diagram of the number of rotations per hour of the rotating member for driving a tool used in an embodiment of the second invention. A model diagram, FIG. 3 is a block diagram of an embodiment of the tool damage detection device used in each of the first and second inventions, and FIG. 4 is a detailed block diagram of the detection device used in the same embodiment. . 1... Storage device 3... Rotation speed detection device 5... Motor shaft 7... Spindle shaft 9... Power transmission section 1
1... Comparison device 13... Control device Fig. 1 ++''f Fig. 2

Claims (1)

[Scope of Claims] 1) The rotational speed of the tool driving rotating member during actual cutting is monitored, and the rotational speed of the tool driving rotating member during machining with a normal tool is determined at the same point in the hourly model diagram. A tool damage detection method that compares the rotation speed and detects tool abnormality when the rotation speed continues to decrease for a set time. 2) monitoring and time-integrating the rotational speed of the tool-driving rotating member during actual cutting, and continuously comparing it with the time-integrated value of the rotational speed of the tool-driving rotating member when machining with a normal tool; A tool damage detection device that detects tool damage when the time integral value continues to decrease for a set time or longer. 3) A rotation speed detection device for a rotating tool driving member, a model diagram storage device that stores a one-hour model diagram of the rotation speed of the tool driving rotating member when machining is performed with a normal tool, and a model diagram storage device that stores a rotation speed one-hour model diagram of the tool driving rotating member when processed with a normal tool; The detected rotation speed is the model line diagram g11.
A tool damage detection device comprising: a comparison device that compares the rotational speed of the device at the same time; and a control device that receives a signal from the comparison device and issues a command indicating an abnormality in the tool. 4) A rotational speed integrator that detects and time-integrates the rotational speed of the tool-driving rotating member during actual cutting, and a one-hour model of the time-integrated value of the rotational speed of the tool-driving rotating member when machining with a normal tool. A model diagram storage device for storing a diagram, a comparison device for comparing an integral value from the rotation speed integrator with an integral value at the same time from the model diagram ti device, and a signal received from the comparison device. A tool damage detection device comprising a control device that issues a command to detect a tool abnormality.