JP2897677B2 - Scrap up detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the rise of scrap generated by press working for punching a fine pattern such as a lead frame, and more particularly to a method for calculating the detection apparatus.

[0002]

2. Description of the Related Art Conventionally, there is a method for detecting dust rising as described in JP-A-61-9933. This consists of a step of obtaining the bottom dead center of the first bound generated by the collision of the stripper with the lower mold or the workpiece (plate material), and a step of comparing the bottom dead center with a set position. By detecting the displacement, the descent is detected. That is, in the graph showing the displacement of the stripper in FIG. 3, when the scrap rises, the bottom dead center position of the first bound when the stripper collides with the plate material is set to the set position (the stripper displacement a− at the time of normal punching). The displacement from the bottom dead center c) on the b line to the bottom dead center c 'is detected, so that it is determined that a scrap climb has occurred by detecting this displacement.

[0003] In the above-described method for detecting dregs rising, when the dregs are small enough to be crushed by the collision of the stripper, a clear displacement difference between the bottom dead center c in the normal state and the bottom dead center c 'when the dregs rising occurs. , There was a risk that the dregs could not be reliably detected. Also,
Even if the waste has a size that is not crushed by the collision of the stripper, it is affected by vibrations (shown by the displacement ab ′ line in FIG. 3) generated when the stripper collides, and the like, and the bottom dead center in a normal state. Since the difference between c and the bottom dead center c ′ at the time of the occurrence of the residue rise may hardly occur, there is also a problem that the detection accuracy of the residue rise is not sufficient.

Therefore, the present inventor has already proposed a measuring method and apparatus improved therefrom as Japanese Patent Application Laid-Open No. Hei 6-134494. In this method, a displacement sensor is mounted on a punching die apparatus, and a target is mounted on a stripper packing plate, and the distance between the die plate and the stripper packing plate is measured to detect a scrap rise. That is, in FIG. 2, the plate material 4 as the material to be processed is first clamped between the stripper packing plate 3 and the die plate 5. At this time, the pressing force of the plate member 4 is given by the plurality of springs 2 arranged above the stripper packing plate 3. From this state, the entire upper die including the punch holder 10 and the punch plate 11 descends, and the punching between the punch 1 attached to the punch plate 11 and the die plate 5 is completed. The scum 6 formed by this punching falls from the scum hole 9 provided in the die plate 5 normally. However, rarely after punching, it may adhere to the tip of the punch 1 and be caught between the plate material 4 and the stripper packing plate 3 or between the die plate 5. In addition, in addition to the above-mentioned scum, burrs generated on the product by punching may fall off. If these foreign substances are caught above or below the plate material 4, they will damage the product, causing a large number of defects.

[0005]

As a device for detecting the waste, a displacement sensor 8 is provided on a die plate 5 and a distance a from a target 7 fixed to a stripper packing plate 3 is monitored. As the operation of the detecting device, as shown in the block diagram of FIG. 4, first, the measured displacement signal from the displacement sensor 8 is converted into an A / D converter 13.
Is converted to a digital value, and a bottom dead center position detector 14 for obtaining a first bound bottom dead center position (displacement) from the digitized signal, a displacement signal and a bottom dead center position signal are inputted, and a predetermined arithmetic expression is inputted. Calculation circuit 15 for calculating the slope value by
A gradient comparison circuit 16 for comparing the obtained gradient value with a gradient value (reference value) obtained in the previous stripper shot, a reference value setting circuit 19 for inputting a reference value, Sometimes, a stop circuit 17 receives a signal from the gradient comparison circuit 16 and transmits a stop signal to the press machine 18.

As the operation of the detecting device, first, the bottom value of the first wave or the peak value of the bottom dead center of the first wave is found from the measured displacement, and the detected value is represented as the value of the shot. Then, those as shown by the following formula (1), compares this value d _i and the value d _i-1 in the shot immediately before the press die, scum up occurred when greater than the set value c As a stop of the press machine.

| D _i -d _i-1 |> c (1)

Here, since the set value c differs depending on the die and the press device, the operator gives the set value by a setting switch. However, since the set value c is determined while observing the indicator indicating the variation, there is a situation in which the value differs depending on the operator, or it is not possible to cope with a change in the variation during operation. In addition, there have been many problems such as overlooking the waste and stopping the press when there is no waste (false alarm).

The present invention has been made in view of the above points, and an object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a descent detecting device which can reduce missed descent and false information. And

[0010]

SUMMARY OF THE INVENTION The present invention relates to a press processing apparatus for punching a fine pattern such as a lead frame, wherein the displacement of the stripper packing plate is detected before and after the stripper packing plate collides with the material to be processed. From the circuit to calculate the displacement gradient immediately before the bottom dead center position, a memory circuit that stores the numerical value of each of a number of consecutive shots of the press die, a standard deviation is calculated from the numerical value of this memory circuit and the set value A standard deviation calculation circuit and a reference value input circuit, and a gradient comparison circuit and a stop circuit for comparing the displacement gradient with the set value as a reference value. A press-up detecting device which determines that the press-up has occurred and stops the press machine.
In addition, this is a scrap rising detection device that sets the reference value to 5σ when the standard deviation value is σ as the set value. Also,
This is a scrap rising detection device that calculates and updates the set value 5σ with respect to the latest displacement of the past several shots.

[0011]

The set value used for the calculation of the dreg rise detecting device is not given by a person, but the detecting device itself stores the values for several shots in the memory circuit, and calculates the standard deviation from this to obtain the set value. In this case, the setting is automatically performed, thereby making it possible to significantly reduce the possibility of missing or false alarm of the dregs rising.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The spill rising detection device of the embodiment is configured as shown in the block diagram of FIG. That is, the displacement sensor 8
The A / D converter 13 converts the signal of the measured displacement a from the A / D converter 13 into a digital value, and the bottom dead center position detector 14 for obtaining the first bound bottom dead center position (displacement) from the digitized signal. And a memory circuit 20 for storing data of the bottom dead center position detector 14 in each shot of the press die. The standard deviation calculation circuit 21 calculates a standard deviation σ of displacement using the data. Here, it is desirable that the number of data is 30 or more. This is because the number of data for which the standard deviation σ is stable is about 30 points. It is appropriate that a value of 5σ is given as the set value. The reason for this is that the probability that the set value deviates from 5 times the standard deviation σ is about 1/10 ⁶ , which means that a false alarm occurs once for 1 million shots (approximately 4 days of press work). Means. In other words, the above-mentioned value is the allowable limit even if a false alarm occurs in the operation. Then, the set value is input to a reference value setting circuit 19 to be used as a reference value, and the slope comparison circuit 16
When the gradient value measured this time exceeds the reference value, a signal is output to the stop circuit 17 and the press machine 18 is stopped.

In the above embodiment, the standard deviation σ is calculated to be 5σ.
Has been described, but this may be calculated with respect to the latest displacement of the past several shots and updated. Then, even if the variation of each shot changes, a false report or the like due to the variation hardly occurs.

Further, as a method of detecting scum, it may be performed by monitoring not only the displacement but also the descent speed of the stripper. The present invention can be applied to any monitor that monitors the value of each shot.

[0015]

As described above, according to the scrap rising detecting apparatus of the present invention, the set value can be automatically set by the reference circuit without having to consider the difference in variation between the die and the press, so that the operation is simplified. In addition, it is possible to prevent human error in setting, and it is possible to perform a press operation with excellent accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a scrap rising detection device according to an embodiment;

FIG. 2 is a sectional view showing a configuration of a mold according to the embodiment;

FIG. 3 is a graph showing the displacement of the stripper in a normal state and at the time of climbing of the waste,

FIG. 4 is a block diagram showing a configuration of a spill rising detection device according to the prior art.

[Explanation of symbols]

 Reference Signs List 1 punch 2 spring 3 stripper packing plate 4 plate material 5 die plate 6 waste 7 target 8 displacement sensor 9 waste hole 13 A / D converter 14 bottom dead center position detector 15 gradient calculation circuit 16 gradient comparison circuit 17 stop circuit 18 press machine 19 Reference value input circuit 20 Memory circuit 21 Standard deviation calculation circuit

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryuji Yonemoto 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture “Inside System Materials Research Laboratory, Hitachi Cable, Ltd.” (58) Fields surveyed (Int. Cl. ⁶ , DB Name) B21D 45/00

Claims (3)

(57) [Claims] In a press working apparatus for punching a fine pattern such as a lead frame, a displacement before and after a stripper packing plate collides with a material to be processed is detected from a displacement of the stripper packing plate, and a displacement immediately before a bottom dead center position is obtained from the displacement of the stripper packing plate. A circuit for calculating the gradient, a memory circuit for storing numerical values in each of several consecutive shots of the press die, a standard deviation calculating circuit for calculating a standard deviation from the numerical value of the memory circuit and setting it as a set value, and a reference value An input circuit, a gradient comparison circuit for comparing the displacement gradient with the set value as a reference value, and a stop circuit, and when the gradient comparison circuit exceeds a reference value based on the standard deviation, it is determined that a scrap has risen. And a press machine for stopping the press machine. 2. The spill rising detecting apparatus according to claim 1, wherein 5σ is set as the standard deviation value σ as the set value. 3. The scrap rising detection apparatus according to claim 1, wherein the set value 5σ is calculated and updated for the latest displacements of the past several shots.