JPH0249811B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for detecting scrap build-up during press working.

[Conventional technology]

When a lead frame for an IC or an iron core of an electric motor is punched and formed using a press machine, so-called punching waste is pushed into the die by the punch.

After pushing in the punched scraps (hereinafter referred to as scraps), the punch performs an upward movement, but at this time a vacuum is created between the punch tip and the scraps, so
A phenomenon in which the scraps that have been pushed up once rises and flies out of the die, that is, so-called scrap lifting, may occur.

When this scrap build-up occurs, the scrap adheres to the die or stripper, resulting in continuous dents on the processed material, resulting in a large number of defective products. This residue also causes breakage or chipping of the punch.

By the way, if the above-mentioned scraps are lifted up and adhere to the surface of the processed material, the stripper will be separated from the die by the thickness of the scraps during punching.
Therefore, conventionally, a method has been proposed for detecting the scrap rising based on the height of the stripper when the punch is positioned at the bottom dead center.

[Problem that the invention seeks to solve]

However, the above conventional method has the following drawbacks.

(a) If the shape of the debris is small, it is not possible to accurately detect the debris. Incidentally, scum build-up mainly occurs when fine processing is required, such as in the case of the lead frame, and the shape of the scum is also small in such processing.

(b) Scrap build-up cannot be detected when the hardness of the processed material is low. This is because the scraps are crushed by the stripper and pushed into the material, so that the height of the stripper does not change due to the scraps rising.

The object of the present invention is to solve such conventional problems.

[Means for solving problems]

If the object is broken or crushed,
Ultrasonic waves called AE (ACOUSTIC EMITION) waves are emitted within an object. In the present invention, this AE
Waves are used to detect debris. That is, in the scrap lifting detection method according to the present invention, an ultrasonic sensor for detecting AE waves is installed at a suitable location of a press machine, and the difference in the output signal of the ultrasonic sensor when scrap lifting is not occurring and when scrap lifting is occurring is detected. Based on this, the occurrence of the above-mentioned waste is detected.

In addition, the present invention detects AE waves that are generated by themselves when scraps or materials are crushed during the pressing process,
The output signal during non-punching is extracted from this output signal, this extracted signal is compared with the output signal during non-punching when no scrap lifting occurs, and the occurrence of scrap lifting is detected based on the difference between these output signals. That's what I do.

Further, in the detection device according to the present invention for carrying out the above method, an ultrasonic sensor for detecting AE waves provided at an appropriate location of the press machine, and a signal of a predetermined value or more output from the ultrasonic sensor are converted into pulse signals. A waveform conversion means for converting the pulse signal into a pulse signal, a means for counting the pulse signal, and a comparison means for comparing the count value of the counting means with a preset value are provided.

Further, the detection device of the present invention includes means for extracting a non-punching operation period of the press machine, and means for detecting that a signal of a predetermined value or more is output from the ultrasonic sensor within the period. There is.

〔Example〕

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

As mentioned above, so-called scrap lifting occurs when punching scraps fly out from the die.

If the above-mentioned scrap lifting does not occur, an AE wave as illustrated in FIG. 3a is generated every time the material is punched out by the press machine. That is, AE waves having substantially the same waveform are generated during each punching operation period T centered at the bottom dead center.

On the other hand, when scraps rise, the material is crushed by the scraps immediately before the period T, and the scraps themselves are also crushed. An AE wave based on this appears.

In this way, the AE wave when debris upstream occurs is different from that when no debris upstream occurs.

Therefore, in an embodiment of the scrap lifting detection method according to the present invention, the above-mentioned AE wave is detected by an ultrasonic sensor, and scrap lifting is detected based on the difference in the output signal of this sensor when no scrap lifting occurs. There is.

FIG. 1 shows an example of a device for implementing such a detection method, and an ultrasonic sensor 1 shown in the figure is disposed in a die or stripper of a press machine (not shown).

This ultrasonic sensor 1 outputs a signal corresponding to the AE wave, and this output signal is amplified by an amplifier 2 and then applied to a comparison circuit 3.

The comparator circuit 3 receives the input AE signal as shown in Fig. 3a.
Since a signal of logic level "1" is output when the value is larger than the threshold value V _r shown in Figure 3a, the same result occurs when the AE signal at the time of non-default rise shown in Figure 3a is output from amplifier 2. As shown in FIG. b, m pulse signals are output from this comparator circuit 3. Furthermore, when the amplifier 2 outputs the AE signal at the time of scrap rising as shown in c in the figure, n (>m) pulse signals are output as shown in d in the figure.

The counter 4 counts the pulse signal output from the comparison circuit 3, and the comparison circuit 5 compares the count value of the counter 4 with a preset value.
The counter 4 is reset by a signal from a rotary cam switch (not shown), for example, when the press machine is positioned at the top dead center.

The comparison circuit 5 is configured to output a waste signal when the count value of the counter 4 is greater than or equal to a preset value. In this embodiment, the preset value is set to m+1, and therefore, the comparison circuit 5 outputs a scrap rising detection signal only when scrap rising occurs.

Note that the above-mentioned scrap rising detection signal is used as a stop signal of the press machine and a scrap rising display signal.

FIG. 2 shows another embodiment of the residue detection device according to the present invention.

This embodiment includes a one-shot circuit 6, an inverter circuit 7 for inverting the output signal of the one-shot circuit 6, and an AND circuit 8 for calculating the logical product of the output signal of the inverter circuit 7 and the output signal of the comparator circuit 3. We are prepared.

The one-shot circuit 6 receives as a trigger signal a timing signal shown in FIG.
A signal having the same time width as the period T is output as shown in FIG. Since this signal is inverted by the inverter circuit 7 as shown in g in the figure, the logic level at the output terminal of the inverter circuit 7 becomes "1" during the non-punching operation period of the press machine. in this way,
The one-shot circuit 6 and the inverter circuit 7 have the function of extracting a non-punching operation period.

The monostable time of the one-shot circuit 6 indicating the above-mentioned punching operation period T varies depending on the operating speed of the press machine, the thickness of the material, etc., and is therefore set appropriately.

As described above, the comparator circuit 3 outputs the pulse signal shown in FIG. 3b when no waste is present, and the pulse signal shown in FIG. 3d when the waste is present.

The pulse signal based on the rise of scraps shown by hatching in d of the same figure is output during the non-punching operation period, that is, during the period when the logic level of the output signal of the inverter circuit 7 is "1". Therefore, in this embodiment, only the pulse signal based on this rising waste is outputted from the AND circuit 8 as the rising waste detection signal.

Note that in the above embodiment, the ultrasonic sensor 1 is disposed on the die or stripper of the press machine, but
It is also possible to arrange one or a plurality of sensors 1 on both of them and to individually process each output signal of these sensors 1 to detect the above-mentioned residue.

Further, it is of course possible to have a microcomputer perform the functions of the comparison circuits 3, 5, counter 4, one-shot circuit 6, AND circuit 8, etc. shown in the above embodiment.

〔Effect of the invention〕

In the present invention, an ultrasonic sensor for detecting AE waves is installed at a suitable location in a press machine, and the occurrence of the above-mentioned waste is detected based on the difference in the output signal of the ultrasonic sensor when no waste is generated and when waste is generated. Detected.

Therefore, even when the shape of punched scraps is small, such as during lead frame molding, or when the hardness of the material is low, scrap build-up can be detected reliably and quickly. In addition to minimizing the occurrence of dents, breakage and chipping of the punch can be reliably prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the waste rise detection device according to the present invention, Fig. 2 is a block diagram showing another embodiment of the same device, and Fig. 3 is a block diagram showing Figs. 2 is a timing chart showing the effect of the embodiment shown in FIG. 1... Ultrasonic sensor, 3, 5... Comparison circuit, 4... Counter, 6... One shot circuit, 8... AND circuit.

Claims (1)

[Claims] 1. An ultrasonic sensor for detecting AE waves is installed at a suitable location on the press machine, and the AE waves naturally generated when scraps or materials are crushed in the press process are detected, and the output signal is used to detect the non-punching process. The feature is that the output signal at the time of the punching is extracted, this extracted signal is compared with the output signal at the time of non-punching when no scrap lifting occurs, and the occurrence of scrap lifting is detected based on the difference between these output signals. A method for detecting scrap in press processing. 2. The scrap lifting detection method in press processing according to claim 1, wherein the ultrasonic sensor is installed on one or both of a stripper and a die of the press machine. 3. An ultrasonic sensor for detecting AE waves installed at a suitable location on the press machine; a waveform conversion means for converting a signal of a predetermined value or more into a pulse signal from a signal output from the ultrasonic sensor; and counting the pulse signal. What is claimed is: 1. A scrap lifting detection device in press working, comprising: a counting means for calculating the count value of the counting means; and a comparison means for comparing the counted value of the counting means with a preset value. 4. An ultrasonic sensor for detecting AE waves installed at a suitable location on the press machine, extracting the non-punching operation period of the press machine, and extracting the output signal during the non-punching operation period from the signal output from the ultrasonic sensor. and a detection means that compares the extracted signal with a reference signal during non-punching when scrap lifting does not occur and detects whether or not a signal exceeding a predetermined value is output. A scrap removal detection device for press processing.