JPH0769133B2 - Long metal strip joint detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a long metal strip for detecting a joint portion of a long metal strip used for manufacturing contact parts such as lead frames and contacts. The present invention relates to a seam detection device.

(Background Art) When manufacturing a lead frame used for a semiconductor device,
Alternatively, when manufacturing contact parts such as contacts, metal strips are used for press processing, etching processing, plating, etc., but since the processing work is performed continuously,
One long metal strip is formed without joining the ends of the metal strip for processing.

The seam portions of the metal strips are usually connected by spot welding, connecting fittings, etc., by overlapping the ends of the metal strips. When commercializing these products, it is necessary to remove the seam part of the metal strip, and in press processing etc., if the seam part is left in the die as it is, there will be problems such as breakage of the mold. Therefore, each work process is performed while monitoring the seam portion, and when the seam is detected, it is possible to take a measure such as temporarily stopping the device.

The present applicant has applied for a seam detection device having a block structure shown in FIG. 3 as a non-contact type detection device for detecting the seam portion of the long metal strip (Japanese Patent Application No. Sho 63).
-86928), this seam detection device uses a circular coil 1 as an oscillation coil, passes a metal strip 2 for detecting a seam inside the oscillation coil, rectifies the output of the oscillator with a rectifier, After removing the oscillation frequency component in the output signal by the filter, the filter output signal is differentiated to detect the differential output level. In this seam detection device, when the seam portion of the long metal strip passes through the oscillation coil, the oscillation frequency changes due to the change in the metal amount of the long metal strip, and the output value changes accordingly. Judge the seam by catching the fluctuation. Here, the purpose of differentiating the output signal of the film and checking the output is to improve the sensitivity for detecting the change in the joint portion and to reliably catch the joint.

(Problems to be Solved by the Invention) However, the conventional seam detection device is a metal strip to be detected, in which the amount of metal does not change so much, for example,
This is effective for simple metal strips that have not been punched, or for lead frames, etc., where it is possible to detect by detecting a rail part where the metal part is continuous. The output variation is too large and is not suitable for the case where the amount of metal in the detection target region largely changes, such as the case where various miscellaneous punching is performed on the metal part. In particular, since the seam detection device observes the differential output, in such a case, there is a problem in that the output level greatly changes even in a portion other than the seam portion, and malfunctions and seam detection become unstable.

By the way, in the actual work, an extremely large variety of products are handled as lead frames and contact parts, and along with this, the patterns formed on the metal strips are also extremely miscellaneous. Therefore, as a seam detection device, there is a strong demand for a seam detection device that does not require operations such as re-adjustment for different products of various types and can be used easily.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to form various patterns such as a metal strip used in manufacturing a lead frame or the like. Even in such a case, it is possible to reliably detect the joint portion of the long metal strip,
An object of the present invention is to provide a seam detecting device for a long metal strip which is easy to handle.

(Means for Solving the Problems) The present invention has the following configuration in order to achieve the above object.

That is, in a metal strip that has been subjected to punching or other processing, the amount of metal varies due to the pattern shape. A seam that detects the seam of a long metal strip that overlaps the ends of the metal strip. A detection device, which includes an oscillator including an oscillation coil installed in the vicinity of the long metal strip, and outputs an oscillation amplitude from the oscillator according to the amount of metal of a detection target portion of the long metal strip. A rectifier that rectifies the output signal, a filter that removes an oscillation frequency component from the output signal output from the rectifier, a control unit that sets a sampling period and a monitoring period, and an output from the filter within the sampling period. The bottom value of the filter signal is detected, the reference value is set to a value less than or equal to the bottom value, and the bottom hold unit holds the reference value within the joint monitoring period. The level of the data output signal, the comparison with the reference value held in the bottom hold unit, characterized in that it comprises a level comparator for outputting a signal when the filter output signal is equal to or less than the reference value.

(Operation) From the oscillator, the oscillation output whose oscillation amplitude changes according to the amount of metal in the detection target portion of the long metal strip is input to the rectifier,
After rectification by the rectifier, the oscillation frequency component is removed by the filter. The filter output signal is input to the bottom hold unit, and when the bottom hold unit is in the sampling period set by the control unit, the bottom value of the filter output signal is read and the seam is detected based on the bottom value. When the reference value to be set is set and is within the monitoring period set by the control unit, the reference value is held in the bottom hold unit, the filter output signal is input to the level comparison unit, and the reference value input from the bottom hold unit is input. The value is compared with the filter output signal, and when the filter output signal becomes equal to or less than the reference value, the signal is output. The seam of the long metal strip is detected by this output signal.

(Examples) Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings.

When a long metal strip is used during production, the metal strip used for forming contact parts such as lead frames or contacts may change the amount of metal at the joint detection target site. However, the lead frame will be described below as an example. Even when used in products other than lead frames, the operation is exactly the same.

FIG. 1 is a block diagram showing the configuration of a seam detecting device for a long metal strip according to the present invention. In the figure, 10 is a lead frame for which a seam is to be detected, and 12 is an oscillating coil installed close to the lower side of the lead frame 10. The oscillation coil 12 is connected to the oscillator 14. The oscillator 14 is an oscillating coil
The oscillation amplitude fluctuates according to the amount of metal of the detection target portion of the lead frame 10 where 12 faces each other. A rectifier 16 receives the oscillation output from the oscillator 14 and rectifies the oscillation output. Reference numeral 18 denotes a filter to which the output signal from the rectifier 16 is input, which removes the oscillation frequency component in the rectified signal. Reference numeral 20 denotes a bottom hold unit to which the filter output signal output from the filter 18 is input. A control unit 22 sets a sampling period for reading the bottom value of the filter output signal and a monitoring period for detecting the seam of the lead frame. During the sampling period, the bottom value is read from the filter output signal input to the bottom hold unit 20, and a reference value that serves as a reference for detecting a seam is set based on the bottom value within the sampling period.
The reference value is set to a value equal to or lower than the bottom value detected during the sampling period. In the monitoring period, the reference value is held in the bottom hold unit 20, the filter output signal is input to the level comparison unit 24, and the level comparison unit 24 compares the level of the filter output signal with the level of the held reference value. Are compared. The level comparison unit 24 outputs a signal when the filter output signal falls below the reference value.

The control unit is manually controlled, and a sampling period and a monitoring period are set at any time.

FIG. 2 illustrates the filter output signal and the output signal from the level comparing section 24 in the joint monitoring period. In the seamless portion of the lead frame, the amount of metal (which is close to the cross-sectional area of the lead frame) changes according to the pattern shape of the lead frame, and the filter output signal changes according to this change. In the bottom hold unit 20, the bottom value (minimum level value) of the filter output signal is read during the sampling period, and the reference value of the filter output signal for detecting the seam is set based on this bottom value. . In FIG. 2, the broken line A indicates the reference value set by the bottom hold unit.

In the filter output signal, the part a passes through the oscillation coil 12 when the lead frame 10 moves,
This is a range where the filter output signal is relatively lowered. In the level comparing section 24, the reference value A and the filter output signal are constantly compared, and the signal is output from the level comparing section 24 in the range where the level of the reference value A is lower than that of the portion a. The seam portion is detected, and it is detected that the seam has passed through the oscillation coil 12 portion. If, for example, an alarm is activated by the output signal of the level comparison unit 24, the worker can take appropriate measures at that time.

The control unit 22 is appropriately turned on and off by an operator, and in actual use, the control unit 22 is turned on for a predetermined initial time when the lead frame starts to be conveyed, sampling is performed, and a seam is detected. The reference value may be set, and then the control unit 22 may be turned off to hold the reference value and start the detection. In the above sampling period, a plurality of repetitive patterns of the lead frame are sampled so that any variation in the metal amount of the lead frame other than the joint portion appears. At the joint, the bottom value of the filter output signal is usually much lower than the reference value. Therefore, in order to prevent malfunction, it is preferable to set the reference value to a value slightly lower than the bottom value.

At the joint portion of the lead frame, at least one repetitive portion of the repetitive pattern of the lead frame is overlapped and connected in order to keep the feed of the lead frame constant. Therefore, at the joint portion, the amount of metal is larger than that at other portions. There is a portion where the filter output signal is below the reference value. This makes it possible to reliably detect the joint portion.

Also, when a seam is detected, after performing the prescribed treatment,
Proceed to the monitoring period for detecting seams. In this case, when different types of lead frames are connected, the control unit 22 is operated again to perform sampling, and the process proceeds to the monitoring period for detecting a seam. It goes without saying that the seam portion of the lead frame is not sampled at the time of sampling.

The bottom hold unit 20 and the level comparison unit described above
24 may be analog-held by the bottom hold unit 20 and compared in an analog manner, or the output signal may be A / D converted and the hold value may be stored in a microcomputer and digitally compared with this hold value. Good.

Although the sampling period and the monitoring period are set by turning on and off the control unit 22 in the above embodiment, the sampling period and the monitoring period are stored in the microcomputer in advance, and the detection device is activated. Then, while automatically sampling and setting the reference value, it is also possible to proceed to the monitoring period and perform the seam detection.

Although the present invention has been variously described above with reference to the preferred embodiments, the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

(Effect of the invention) According to the seam detection device for a long metal strip according to the present invention,
At the time of sampling, the bottom value of the filter output signal is read and held, and the reference value set to a value less than the bottom value is compared with the filter output signal during the monitoring period to detect the seam. Even if the amount of metal in the detected portion varies considerably, such as a metal strip used when manufacturing contact parts such as, the joint portion can be reliably detected.

Also, at the start of detection, sampling is performed first, and the reference value is automatically set based on this sampling value, so it can be used in the same way for any type of long metal strip, and it can be used in the same way. Even in the case of manufacturing the above product, it is possible to eliminate the trouble of setting the detection level each time and so on.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a seam detecting device for a long metal strip according to the present invention, and FIG. 2 is a graph showing a filter output signal and an output signal of a level comparison unit, FIG. 3 is a block diagram showing a conventional seam detection device. 10 ... Lead frame, 12 ... Oscillation coil, 14 ... Oscillator, 16 ... Rectifier, 18 ... Filter, 20 ... Bottom hold section, 22 ... Control section, 24 ... Level comparison section.

Claims (1)

[Claims] 1. A seam of a long metal strip having a metal strip that has been subjected to a punching process or the like, in which the amount of metal varies depending on the pattern shape, and the ends of the metal strip are overlapped. A seam detection device for detecting, comprising: an oscillator including an oscillating coil installed in the vicinity of the long metal strip, and an oscillation according to the amount of metal of a detection target portion of the long metal strip from the oscillator. A rectifier that rectifies an output signal that is output with amplitude, a filter that removes an oscillation frequency component from the output signal that is output from the rectifier, a control unit that sets a sampling period and a monitoring period, and the filter in the sampling period. The bottom value of the filter signal output from the device is detected, the reference value is set to a value less than or equal to the bottom value, and the bottom holding unit holds the reference value within the joint monitoring period. A level comparing section for comparing the level of the filter output signal with the reference value held in the bottom hold section, and for outputting a signal when the filter output signal is below the reference value. Measuring device for seam of strip metal strip.