JPS632647A - Tool breakage/damage detecting method - Google Patents

Abstract

PURPOSE:To detect a breakage/damage of a tool in process and enable the optimum activity at the breakage/damage time by detecting it when the detecting signal of a contact detector is turned off during working operation of a workpiece by means of the tool. CONSTITUTION:High-frequency current supplied from a power source 19 flows through the coil 9 of an exciting coil 7 and high-frequency magnetic field is generated at a core 10. When the tool 4 of a working machine 1 makes contact with a workpiece 5, the high-frequency current H flowing in a loop through a frame 2, a main shaft part 3, the tool 4 and the workpiece 5 is generated by said high-frequency magnetic field. The high-frequency current H generates the high-frequency magnetic field around the core 11 of the detecting core 10 to induce the high-frequency current, which functions as the output signal of the detecting coil 10. A detecting element 20 processes said output signal and receives the detecting signal or the breakage/damage signal. Said breakage or damage signal is connected to the skip input of a CNC controller to interrupt the feeding activity of the tool 4 or the workpiece 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting tool breakage tJll in a machine tool, and is used for in-process detection of tool breakage during cutting.

(Prior art and its problems) Conventionally, a device for detecting contact between a tool of a processing machine and a workpiece by using an electromagnetic phenomenon caused by contact between the two has been disclosed in Japanese Patent Publication No. 1B-48861, Tokuko Showa 5
Publication No. B-41983 or Japanese Patent Application No. 1983-53010
Various embankment plans have been made, as shown in No. Such a contact detector provides a signal of the starting point of machining the workpiece by the tool and, if such starting point is not within a predetermined range, a breakage signal indicating that the tool is broken. Detection of tool breakage is performed by outputting the information. However, in this detection method, the breakage of the tool in the cutting before the cutting is detected in the post process, and the detection is slower than in-process detection, which detects the breakage at the time of cutting during cutting. Jii [cannot be processed when broken.

- On the other hand, for in-process detection of tool breakage, a method has been implemented that detects the acoustic emission emitted at the time of tool breakage, but this requires special sensors and detection equipment, and requires installation and maintenance of the sensor. It is not easy to do so, and there are problems with the commercial area.

(Technical means for solving the problem) The present invention was made in view of the above-mentioned problem, and utilizes a conventionally used contact detector for detecting contact between a tool and a workpiece. The present invention provides a method for detecting fold m in-process.

The technical means for this purpose is to use a contact detector A that detects the contact between the tool 4 and the workpiece 5 by detecting the current 1 that flows in the closed circuit formed by the contact between the tool 4 and the workpiece 5 of the processing machine. This is a tool breakage detection method in which breakage of the tool 4 is detected when the detection signal S6 of the contact detector A is turned off while the workpiece 5 is being processed by the tool 4.

(Example) The present invention will be described below based on an example with reference to the drawings.

In FIG. 1, a processing machine 1 has a main shaft 3 that moves relative to a frame 2, and a tool 4 attached to the main shaft 3 contacts a workpiece 5 to perform processing. This tool 4
an annular sensor part 6 attached to the main shaft part 3 so as to penetrate therethrough in order to detect contact between the main shaft part 3 and the workpiece 5;
An alarm A consisting of a control section I8 is provided.

Referring also to FIG. 2, the sensor section 6 includes an excitation coil 7 and a detection coil 10 each having a coil 9.12 uniformly wound around an annular core 8.11 made of a magnetic material such as ferrite. , are arranged close to each other with an annular shielding plate 13 made of a magnetic material such as an iron plate sandwiched therebetween. More specifically, for example, as the cross section is shown in FIG. 3, the excitation coil 7, the detection coil 10, and the shielding plate 13 are housed in an annular casing 14 made of a metal material such as aluminum and having a U-shaped cross section. Stored, synthetic resin 15
is potted and fixed, and is covered with a cover 16 made of synthetic resin. The excitation coil 7 and the detection coil IO are designed not to contact the casing 14 for insulation, and the shield plate 13 is designed not to contact both side walls 14a, 14b of the casing 14 at the same time. A flange portion 14c is provided on the outer periphery of the casing 14 for installation, and is machined with bolts 17.
It is attached to 11.

As shown in FIG. 2, the control section 18 includes a power supply section 19 for passing a high-frequency current through the excitation coil 7, and a detection section 20 for obtaining a detection signal S6 and a breakage signal S7 from the output signal of the detection coil 10. This is housed in a separate housing, and is installed and wired within the control panel of the processing machine 1. The power supply unit 19 includes an oscillation circuit and a power amplification circuit of several K11z to several hundred KHz, and is capable of adjusting the frequency and output power. Detection section 20
For example, as shown in FIG. 4, the circuit comprises an amplifier 21, a detector 22, a waveform shaper 23, an integrator 24, an output section 25, an inverter 26, and an AND 27, the amplification of which can be adjusted by a separator 21a. , AND27 are connected with a signal S8 indicating that cutting is in progress. The operation of this device is to amplify and detect the output signal of the detection coil 10, as shown in the waveform changes shown in Figs. 5 and 6. - Signals above a certain level are converted into pulses with a certain waveform. However, when a certain number of pulses (here, 11i1) or more continue, a detection signal S6 is output.

After the detection signal S6 is output, the signal S8 is input while the spindle is rotating. If the tool 4 breaks during this period, the output from the detection coil 10 disappears, and the detection signal S
6 is turned off, the signal S7 is output at the same time. In FIGS. 5 and 6, Sl, S2, S3.
S4. S5, 56, 57 and S8 indicate the signal states at the same reference numerals in FIG. The manner in which the signal S7 is output is shown.

That is, a high frequency current flows through the coil 9 of the excitation coil 7 by the power supply section 19, and a high 11il wave magnetic field is generated in the core 10. When the tool 4 for machining Ill and the workpiece 5 come into contact, the high-frequency magnetic field generates a high-frequency current H that flows in a loop through the frame 2, the main shaft portion 3, the tool 4, and the workpiece 5 as shown in FIG. A high frequency magnetic field is generated in the core 11 of the sensing coil 10 by the high frequency current H, which induces a high frequency current in the coil 12, which becomes the output signal S1 of the sensing coil 10. This output signal S1 is processed by the detection section 20 as described above, and a detection signal S6 or a breakage signal S7 is output.

This breakage signal S7 is, for example, CNC1! By connecting to the skip human power of II control device, folding FM signal S
Simultaneously with the output of step 7, the feeding of the tool 4 or workpiece 5 stops, and at that time, the position variable of the tool 4 or workpiece 5 is imported into the system variable of the user macro, and the imported variable is set to the normal position (i.e., at the end of machining). tool or workpiece position)).
1fl can be easily detected at the CNC control position, and subsequent processing, such as generation of an alarm and replacement of the workpiece 5 and tool 4, can be appropriately handled.

In the embodiment described above, the detection section 20 has the configuration shown in FIG. 4, but various other configurations are possible.For example, the integrator 24 may be configured with a synchronous counter.
By inserting an appropriate noise filter or comparing the signal with the signal from the power supply section 19, it is also possible to cancel signals other than the signal caused by the high frequency current I, or to detect by detecting a change in the phase of the detection signal. In place of the inverter 26 and the AND 27, other circuit elements, such as a NAND, may be used.The signal S8 is omitted and the broken signal S
The person receiving the 7 can also judge the timing. Furthermore, it is also possible to detect folding by determining the on/off timing and whether the logic is positive or negative based only on the detection signal S6.

Using the above-mentioned detector A, a series of steps are performed, including g1 recognition of the presence or absence of breakage of the tool 4 due to post-processing, detection of the starting point of machining the workpiece by the tool 4, and detection of breakage of the tool 4 due to in-process during machining. It is also possible to perform a detection operation. The processing machine 1 includes machine tools, including machines in which the spindle 3 is fixed and the workpiece 5 moves, and machines in which the spindle 3 does not rotate, and an excitation coil or a detection coil is attached to the frame 2 or the workpiece 5 side. This should be interpreted as a design variation of the present invention.

(Effects) According to the present invention, tool breakage can be easily and reliably detected using a contact detector that detects contact between a tool and a workpiece. Moreover, since tool breakage can be detected in-process, optimal treatment can be carried out in the event of tool breakage.To implement the method of the present invention, it is only necessary to make simple improvements to the contact detector. It can be implemented at low cost.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a front view showing the detection device attached to a processing machine, FIG. 2 is a perspective view including a partial block diagram of the detection device, and FIG. 3 is a sensor section. FIG. 4 is a block diagram showing an example of a detection section, and FIGS. 5 and 6 are diagrams showing examples of signal waveforms of each part. A...Detector (contact detector), old...High frequency current (
Current), S6...Detection signal, S7...Breakage signal, ■
...Processing machine, 2...Frame, 3...Spindle part, 4
...Tool, 5...Workpiece, 6...Sensor part, 10
...Detection coil, 19...Power supply section, 20...Detection section.

Claims (1)

[Claims] A contact detector that detects the contact between the tool and the workpiece by detecting the current flowing in a closed circuit formed by the contact between the tool of the processing machine and the workpiece, and the contact detector detects the contact between the tool and the workpiece while the workpiece is being processed by the tool. A tool breakage detection method that detects breakage of the tool when the detection signal of the tool turns off.