JPH0366971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a clearance abnormality detection device for detecting an abnormality in the clearance between a die and a punch in press working.

[Conventional technology]

Generally, in press processing, the clearance on one side of the die and punch not only has a large effect on the punch's shear load or shear resistance and shear workload, but also affects the scrap removal force (stripping). . For example, in mild steel, stainless steel, brass, aluminum alloy, etc., when the clearance is 20% of the plate thickness, the scrap removal force is minimum, and during general punching work,
The scraping force is approximately 20% of the shear load. In addition, when the clearance is small, such as when shearing precision parts with a large shear surface, the scrap removal force is
Sometimes it is about the same as the shear load. Therefore, if the clearance is too small, the life of the mold will be significantly shortened. On the other hand, as the clearance increases, the curvature of the punched product also increases and burrs occur. In short, in press working, unless the clearance between the die and the punch is in an appropriate state, there are problems in that the force required for pressing becomes excessive and the press working accuracy decreases.

[Problem to be solved by the invention]

Therefore, attempts have recently been made to dynamically measure this clearance during press working to monitor whether or not the clearance is appropriate. However, when performing this clearance measurement over a long period of time, it has been difficult for conventional clearance measurement devices to measure the clearance with high accuracy due to the influence of external environments such as temperature changes, humidity changes, and mechanical vibrations. Therefore, detection of clearance abnormalities is no longer accurate, and as a result,
This causes a decline in press processing accuracy and press quality.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a clearance abnormality detection device that can detect abnormalities in the clearance between a die and a punch with high accuracy.

[Means to solve the problem]

The present invention has a detection coil and applies a high-frequency current to the detection coil to electromagnetically reduce the clearance between a die on which a plate is placed and a punch that fits into the die and presses the plate. A clearance measurement section that performs contact measurement and outputs a measurement signal indicating the clearance, and a clearance measurement section that is provided in the same structure as this clearance measurement section and located close to the clearance measurement section, and is generated when the detection coil is energized. a first error compensator that outputs a first compensation signal for correcting an error in the measurement signal caused by heat generation; a second error compensator that outputs a second compensation signal that compensates for errors caused by temperature changes and mechanical vibrations in the measurement signal by measuring displacement; 2nd above
a clearance calculation section that calculates a clearance with the error of the measurement signal compensated for based on the compensation signal of the above, and a clearance calculation section that compares the clearance calculated by the clearance calculation section with a preset reference value and based on the comparison result. and an abnormality detection section that detects an abnormality in the clearance.

[Effect]

The present invention always automatically corrects clearance errors due to external causes such as temperature changes and mechanical vibrations, as well as internal causes such as heat generation due to energization of the displacement meter, when detecting abnormalities in the clearance between the punch and the die. Therefore, the influence of changes over time is eliminated, and abnormalities in the clearance between the punch and the die can be accurately and stably detected over a long period of time.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the clearance abnormality detection device of this embodiment. This device includes a clearance measuring section 4 that measures the clearance between a die 2 and a punch 3 mounted on the press body 1, and a clearance measuring section 4 that is installed on the press body 1 to eliminate errors caused by changes in the measurement environment of the measured value. an error compensating section 5 for compensating, a clearance calculating section 6 mainly composed of a peak value hold circuit and a subtracting circuit that input the output values from the clearance measuring section 4 and the error compensating section 5 to calculate the true clearance; An anomaly detection section 7 connected to the output side of the clearance calculation section 6, which compares a preset setting value with the calculated clearance and detects a clearance anomaly based on the comparison result, and an output of the anomaly detection section 7. It consists of a display unit 8, which is connected to the side and consists of a printer or cathode ray tube that displays detection results and clearance values. The clearance measuring section 4 consists of a non-contact displacement meter 12 mounted on the side of the punch holder 9 holding the punch 3 so as to face the target 10 at a certain distance when the punch 3 is lowered. There is. As shown in FIG. 2, this non-contact displacement meter 12 includes a cylindrical holder 13, a detection coil 14 installed inside the open end of the holder 13 facing the target 10, and a detection coil 14 disposed inside the holder 13. For example, in the detection coil 14,
A clearance detection signal SA that generates a magnetic field by applying a 254.4kHz square wave high-frequency current and has a voltage proportional to the displacement (clearance)
a conversion circuit 15 that outputs to the clearance calculation section 6
, a nut 16 into which the holder 13 is screwed, and a screw 17 supported by the nut 16 and attached to the die holder 11.
It consists of an L-shaped mounting body 18 that is fixed to the mounting body 18. The position of the holder 13 is adjusted in advance by screwing it through a nut 16 so that the distance between the detection coil 14 and the target 10 corresponds to the distance between the die 2 and the punch 3, that is, the clearance. In this case, the physical distance between the detection coil 14 and the target 10 is the same as that between the die 2 and the punch 3.
It is not the distance or clearance itself, but is set to a size that can be adjusted manually. Therefore, the clearance detection signal SA output from the detection coil 14 is not a signal indicating the true clearance, and is electrically converted into a signal indicating the true clearance by the conversion circuit 15. . This conversion circuit 15 is
It is connected to the input side of the clearance calculation section 6. On the other hand, as shown in FIG. 3, the error compensator 5 includes a first error compensator 5a and a second error compensator 5b. The first error compensating section 5a is a so-called "dummy" having exactly the same structure as the clearance measuring section 4, and includes a cylindrical holder 22 and an open end of the holder 22 on the punch 3 side. The detection coil 23 installed inside the part and the holding body 2
a conversion circuit 24 that is installed in the detection coil 23 and generates a magnetic field by applying a high frequency current, for example, a 254.4kHz square wave, to the detection coil 23 and outputs a clearance detection signal SB having a voltage proportional to the displacement (clearance); It consists of a nut 21 into which a holder 22 is screwed, and an L-shaped mounting body 20 which holds this nut 21 and is fixed to the press body 1 with screws 19. Then, the conversion circuit 24 is
It is connected to the input side of the clearance calculation section 6. Further, the second error compensating section 5b includes the holding body 2
2. A screw 19, a nut 21 and a mounting body 20 are provided at the open end of the holding body 22.
The image sensor 25 is composed of a one-dimensional image sensor 25 such as a linear sensor, which detects minute displacements caused by thermal expansion due to temperature changes, mechanical vibrations, etc., and converts them into electrical signals. The one-dimensional image sensor 25 is
It is attached to the press main body 1 via a metal fitting (not shown) so as to face the tip of the holder 22 on the detection coil 23 side in close proximity to and spaced apart from each other. It is set to detect minute displacements of the tip of the body 22. The one-dimensional image sensor 25 and the high-frequency oscillation circuit 24 are connected to each other via an amplification circuit (not shown).
It is connected to the input side of the clearance calculation section 6. The holding body 22 is provided at a position so that the detection coil 23 does not perform actual distance measurement, that is, it functions as a dummy. Therefore, the clearance calculation section 6 temporarily holds the minimum value of the clearance measurement signal SA from the conversion circuit 15 as a clearance, and also uses the clearance measurement signal SA from the high-frequency oscillation circuit 24.
a first compensation signal SB for compensating for measurement errors caused by heat generation of the detection coil 14 itself, that is, internal causes, of the clearance measurement signal SA output from the clearance measurement signal SA;
It compensates for the displacement of the holder 13 holding the detection coil 14 outputted from the one-dimensional image sensor 25 due to thermal expansion due to temperature changes in the measurement environment and mechanical vibration of the press body 1, that is, measurement errors caused by external causes. A second compensation signal SC is provided for subtracting the sum of the second compensation signals SC. The abnormality detection section 7 is mainly composed of a comparison circuit, and converts the compensated clearance measurement signal SD outputted from the clearance calculation section 6 into a preset upper limit value CU and lower limit value CL. is compared, and if it is outside the range of these upper limit value CU and lower limit value CL, an abnormality detection signal SE is output to the display section 8. Further, this abnormality detection section 7 is connected to a punch holder 9.
It is also electrically connected to the lifting drive unit 1a that lifts and lowers the ram 26 to which the ram 26 is attached, and receives an abnormality detection signal.
It is provided to output SE.

Next, the operation of the clearance abnormality detection device of this embodiment will be described.

First, by screwing the holder 13 into the nut 21, the distance between the detection coil 14 and the target 10 is adjusted to an appropriate state. That is, the clearance measurement signal SA is adjusted so as to indicate the clearance between the die 2 and the punch 3. Next, the work 27 is placed on the die 2, the ram 26 is lowered, and the punch 3 punches the work 27 into a predetermined shape. At this time, the target 10 is connected to the detection coil 1.
Opposed to 4. Since a high frequency current is applied to the detection coil 14 from the conversion circuit 15, a magnetic field is generated. Eddy currents are induced in the target 10 by the lines of magnetic force that constitute this magnetic field. As a result, the impedance of the detection coil 14 changes due to the generated eddy current, and the voltage value of the high frequency current also changes. The clearance can be determined by this change. Thus, the clearance measurement signal SA with a voltage value indicative of the clearance
is output to the clearance calculation section. On the other hand, the one-dimensional image sensor 25 is calibrated so that the second compensation signal SC becomes zero when the open end of the holder 22 is at the reference position. Furthermore, a high-frequency current having the same frequency as that of the detection coil 14 is applied to the detection coil 23 . In short, the first compensation signal SB output to the clearance calculation section 6 is for compensating for measurement errors due to heat generation due to power feeding to the detection coil 19, that is, internal causes. On the other hand, the second compensation signal SC is for compensating for clearance measurement errors caused by external causes such as displacement of the holder 13 holding the detection unit 14 due to thermal expansion due to temperature changes in the measurement environment or mechanical vibrations. be. However, in the clearance calculation section 6,
The sum of signal SB and signal SC is subtracted from signal SA,
The compensated clearance signal SD is sent to the abnormality detection section 7.
is output to. Next, in this abnormality detection section 7, the clearance signal SD is divided into an upper limit value CU and a lower limit value.
A comparison operation is performed to determine whether or not it exists with CL.
If the clearance signal SD is not between the upper limit value CU and the lower limit value CL, an abnormality detection signal SE is output to the display section 8 and the lifting drive section 1a, the press processing is temporarily interrupted, and the display section 8 A message indicating that the clearance is abnormal will be displayed. On the other hand, when the clearance signal SD is within the range between the upper limit value CU and the lower limit value CL, the abnormality detection signal SE is not output, but the measured clearance is displayed on the display 8.
is output to.

In this way, the clearance anomaly detection device of this embodiment automatically compensates for measurement errors due to external causes such as temperature changes and mechanical vibrations and internal causes such as heat generation of the detection coil when measuring the clearance between the punch and the die. Therefore, abnormalities in the clearance can be detected with high accuracy and stability over a long period of time. Generally, in press processing, the clearance on one side of the die and punch not only has a large effect on the punch's shear load or shear resistance and shear workload, but also affects the scrap removal force (stripping). . Further, when the clearance is small, such as when shearing a precision component with a large shear surface, the scrap removal force may be approximately the same as the shear load.
Therefore, when the clearance is too small,
The life of the mold will be significantly shortened. On the other hand, as the clearance increases, the curvature of the punched product also increases and burrs occur.
In short, in press working, unless the clearance between the die and the punch is in an appropriate state, there are problems in that the force required for pressing becomes excessive and the press working accuracy decreases. However, according to the clearance abnormality detecting device of this embodiment, the accuracy of detecting abnormality in the clearance is improved, so that when the clearance is not in an appropriate state, the above-mentioned problem can be solved by immediately providing feedback to the lifting drive unit 1a. It is possible to improve the press quality and extend the life of the mold.

In addition, in the above embodiment, the non-contact displacement meter 1
2 and target 10, that is, the clearance in the horizontal direction in Figure 1 is measured only at one location, but it is also possible to measure the clearance at multiple locations, for example, the clearance in the longitudinal and lateral directions at the same time. It's okay. Further, in the above embodiment, the target 10 is attached to the punch 3 side and the non-contact displacement gauge 12 is attached to the die 2 side, but they may be attached in reverse positions. Additionally, as long as clearance measurements are possible,
Target 10 may be omitted. Furthermore, instead of the one-dimensional image sensor 25, a displacement meter, for example a displacement meter using a differential transformer, may be used. Furthermore, although the error compensating section 5 is attached to the press body 1, the installation location may be arbitrarily selected as long as it is under the same measurement conditions as the clearance measuring section 4.

〔Effect of the invention〕

The clearance abnormality detection device of the present invention always automatically corrects errors due to external causes such as temperature changes and mechanical vibrations as well as internal causes such as heat generation of the displacement meter itself when measuring the clearance between a punch and a die. Therefore, the influence of changes over time is eliminated, and clearance abnormalities can be detected accurately and stably over a long period of time. Therefore, if the clearance is not in proper condition,
Immediate feedback and problem solving can not only improve press quality but also contribute to extending the life of the mold.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of a clearance abnormality detection device according to an embodiment of the present invention, Fig. 2 is an enlarged view of the clearance measuring section in Fig. 1, and Fig. 3 shows the first and second errors in Fig. 1. It is an enlarged view of a compensation part. 2: Dice, 3: Punch, 4: Clearance measurement section, 5a: First error compensation section, 5b: Second error compensation section, 6: Clearance calculation section, 7: Abnormality detection section, 14: Detection coil.

Claims (1)

[Claims] 1. The clearance between the die on which the plate is placed and the punch that fits into the die and presses the plate is electromagnetically measured in a non-contact manner by applying a high-frequency current to the detection coil. a clearance measuring section that outputs a measurement signal indicating the clearance, and a clearance measuring section that is provided in the same structure as the clearance measuring section and is located close to the clearance measuring section, and that is configured to handle the heat generated when the detecting coil is energized. a first error compensator that outputs a first compensation signal for correcting the clearance error of the measurement signal caused by the error; a second error compensator that outputs a second compensation signal that corrects clearance errors caused by temperature changes and mechanical vibrations in the measurement signal by measuring the measurement signal, the first compensation signal, and the measurement signal; a clearance calculation unit that calculates a clearance with the clearance error of the measurement signal corrected based on a second compensation signal; and a clearance calculation unit that compares the clearance calculated by the clearance calculation unit with a preset reference value and obtains the comparison result. A clearance abnormality detecting device comprising: an abnormality detecting section that detects an abnormality in the clearance based on the above.