JPH06114689A - Tool breakage sensing device of printed wiring board contour processing machine - Google Patents

Abstract

PURPOSE:To certainly sense breakage of a tool under the process of processing the contour of a printed circuit board 2 automatically on the real time basis. CONSTITUTION:A microphone 3 to capture the machining sounds of a tool is mounted on the spindle 5 of a processing machine 1 for the contour of a printed circuit board, and the obtained signal from the microphone 3 is amplified to a specified level by a preamplifier 8 and main amplifier 9, and the amplified signal is subjected to the specified processing by a signal processing device 19, which issues a tool break signal if the resultant signal level after processing is below the set threshold. During processing, a processing output signal is emitted, and a failure sensing circuit 13 is operated to monitor if any tool breakage arises.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool breakage of a printed wiring board contour processing machine capable of reliably catching and detecting an abnormality that a tool mounted on a main shaft portion is broken due to inappropriate contour machining conditions, tool wear, or other factors. Regarding a detection device.

[0002]

2. Description of the Related Art In recent years, printed wiring boards used in various electronic devices have a tendency that their outer shapes are small and complicated as the devices to be housed are made smaller and the space to be housed is narrowed. In order to process such a small and complicated printed wiring board, when processing a curved portion having a small radius, for example, a very thin end mill with a diameter of 0.79 mm to 1.27 mm is used. Was.

However, when machining with such a thin tool, the tool often breaks during machining.
When this tool is damaged, not only the tool itself has to be replaced, but also the processing must be restarted from the beginning, or the one being processed must be discarded and a new printed wiring board to be processed must be installed again. Therefore, it is necessary to detect the breakage of this tool as soon as possible.

Usually, as a method of detecting such a tool breakage, a method of detecting a load change of the spindle, a method of detecting a generation of chips and an AE (Acoustic Emiss) are used.
Ion) method.

The method of detecting the load fluctuation of the spindle is carried out by mounting a torque detector on the spindle for rotating the tool and detecting the fluctuating torque generated when the tool is broken. Are suitable. In addition, the detection method based on the generation status of chips is to place an optical sensor near the tool, constantly observe the generation status of chips, and judge the tool damage when the generation of chips disappears. It is suitable for soft workpieces where powder is continuously generated. Furthermore, in the AE method, the detector is brought into contact with the workpiece at a position apart from the tool,
This is a method for detecting tool breakage by the presence or absence of elastic waves generated during cutting, and was applied to materials with high elasticity.

As described above, these methods are selected in consideration of the material and size of the work piece or the size of the tool, and are not particularly suitable for the printed wiring board. Was selected according to the shape and size of the printed wiring board that is the workpiece, and was applied.

[0007]

The above-described conventional tool breakage detection method has a problem that it cannot be applied to a printed wiring board. That is, in the detection method based on the load fluctuation of the spindle, since the tool is thin, it is difficult to distinguish the torque fluctuation when it is broken, and it is difficult to detect the torque fluctuation when it is broken. Also,
In the method of observing the chip generation status, if the resin plate such as a printed wiring board, the generation status of the chips is not continuous,
It is difficult to determine whether the breakage is due to breakage or the breakage of chips. On the other hand, the AE method cannot be applied because it is difficult to capture the elastic waves generated by the printed wiring board.

An object of the present invention is to automatically detect a tool breakage by detecting an abnormal sound generated when the tool breaks due to tool wear or other factors on the outer shape processing, and to obtain a highly accurate detection of the printed wiring board outer shape. It is to provide a tool breakage detection device for a processing machine.

[0009]

A tool breakage detection device for a printed wiring board contour processing machine according to the present invention is attached to a main shaft portion for holding and rotating a tool of the printed wiring board contour processing machine, and a microphone for capturing cutting noise. And a signal processing unit that processes a cutting sound signal obtained from this microphone, and a signal level value processed by this signal processing unit and a set threshold level value are compared, and the signal level value is the threshold value. And a comparison circuit section that outputs a signal indicating a tool breakage when the level is lower than the level value. Further, the signal processing unit includes an amplifier circuit that amplifies the cutting sound signal, a band pass filter that extracts a predetermined frequency bandwidth of the cutting sound signal to be amplified, and a rectifier that rectifies the extracted frequency body signal. It is characterized by having a circuit.

[0010]

The present invention will be described below with reference to the drawings.

FIGS. 1 (a) and 1 (b) are views showing a main part of a printed wiring board contour processing machine for explaining an embodiment of a tool breakage detection device for a printed wiring board contour processing machine according to the present invention. It is a block diagram which shows the structure of a tool breakage detection apparatus. As shown in FIG. 1A, this tool breakage detection device is equipped with a microphone 3 attached to a main shaft portion 5 having a main shaft 7 for attaching and rotating a tool 6, and a microphone 3 for capturing a tool cutting sound, and a cutting obtained from the microphone 3. A preamplifier 8 and a main up 9 for amplifying a sound signal to a predetermined level, and a signal for processing the amplified signal and comparing the processed signal with a threshold value and outputting an abnormal signal when the value is below the threshold value. It has a processing unit 19. Further, the signal processing device 19 sends an abnormal signal to the NC device 21.

As shown in FIG. 1B, the signal processing device 19 includes a bandpass filter 10 for extracting the high frequency component of the signal of the tool cutting sound obtained by further amplifying the output of the preamplifier 8 by the main amplifier 9, and a bandpass filter. A specific wave rectifier circuit 11 for extracting a specific frequency component for detecting a signal from the filter 10 and a signal from the specific wave rectifier circuit 11 are input and compared with a preset threshold value, which is lower than the preset threshold value. And a comparator 12 that outputs a signal when
It has a timing generation circuit 14 for obtaining a monitoring signal from the C device 21 and outputting a processing output signal.

Here, the timing of the monitoring signal 16 of the CN device 21 is such that when the spindle 7 starts machining (the tool 6 and the printed wiring board 2 are not in contact with each other and the spindle 7 is rotating (transmitted as an ON signal). Further, when the outer shape processing is completed, it is inputted as an OFF monitoring signal from the NC device 21, a processing signal output is outputted from the timing generation circuit 14, and the processing signal output 17 and the abnormal value output of the comparator 12 are detected as abnormal. It is input to the circuit 13. The abnormality detection circuit 13 outputs the abnormality signal of the comparator 12 and the timing generation circuit 1
When a machining signal is output from 4, the tool is broken and a tool breakage signal is output.

On the other hand, since the frequency body in the peak region of the cutting sound differs depending on the thickness and material of the printed wiring board 2, the frequency band in the peak value region of the cutting sound is investigated in advance and the frequency band of the bandpass filter 10 is set. Should.

2 (a) to 2 (d) are graphs showing signal levels at various parts of the tool breakage detection device of FIG. First, as shown in FIG. 2A, the cutting sound signal is at level L0 and lower than the threshold signal level LS when the tool is not in contact with the printed wiring board. Next, the tool comes into contact with the printed wiring board, and as shown in FIG. 2 (b), the timing generation circuit 14 sends a processing output signal to the abnormality detection circuit 13 upon receipt of a monitoring signal from the NC device 21 which is the start of monitoring. Then, the tool starts cutting, the tool cutting sound signal 4 level becomes Ly, which is higher than the set threshold level LS, and the abnormal signal level is 0.
Becomes This indicates a state where the tool is cutting normally without breaking.

When the tool cutting sound signal level becomes lower than the set threshold value 22 level LS during cutting as shown in FIG. 2 (c), the comparator 12 outputs an abnormal signal and FIG. 2 (d). As shown in, the abnormality detection circuit 13 sends the level 1 of the tool breakage signal indicating that the tool has broken, to the NC device 21. Then, the NC device 21 sends an operation stop signal to the spindle and the stage as needed.

[0017]

As described above, the present invention focuses on the fact that the cutting sound at the time of cutting the printed wiring board is relatively stable, and a microphone for capturing the cutting sound generated by the tool,
A tool breakage of a printed wiring board external shape processing machine that can automatically and reliably detect tool breakage in real time during external shape processing by providing a means for processing the cutting signal obtained from the microphone and detecting the cutting sound signal that decreases when broken There is an effect that a detection device can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a printed wiring board contour processing machine for explaining an embodiment of a tool breakage detection apparatus for a printed wiring board contour processing machine according to the present invention, and a block diagram showing a configuration of the tool breakage detection apparatus. Is.

FIG. 2 is a graph showing signal levels in various parts of the tool breakage detection device of FIG.

[Explanation of symbols]

 1 Stage 2 Printed Wiring Board 3 Microphone 5 Spindle 6 Tool 7 Spindle 8 Preamplifier 9 Main Amplifier 10 Bandpass Filter 11 Specific Wave Rectifier Circuit 12 Comparator 13 Abnormality Detection Circuit 14 Timing Generator 19 Signal Processor 21 NC Device

Claims (2)

[Claims] 1. A microphone mounted on a spindle for holding and rotating a tool of a printed wiring board contour processing machine and capturing a cutting sound, a signal processing section for processing a cutting sound signal obtained from the microphone, and And a comparison circuit unit that compares a signal level value processed by the signal processing unit with a set threshold level value and outputs a signal indicating tool breakage when the signal level value is lower than the threshold level value. A tool breakage detection device for a printed wiring board contour processing machine, which is characterized in that 2. The signal processing unit, an amplifier circuit for amplifying the cutting sound signal, a bandpass filter for extracting a predetermined frequency bandwidth of the cutting sound signal to be amplified, and a signal of the extracted frequency body. 2. A tool breakage detection device for a printed wiring board contour processing machine according to claim 1, further comprising a rectification circuit for rectifying.