JPH0475800A - Press device incorporating crack detecting part into tool - Google Patents

Abstract

PURPOSE:To detect a crack in a real time with high accuracy by detecting the information on the generation of the crack, converting and processing the detection signal and deciding whether the crack is generated in a work or not based on the processed signal. CONSTITUTION:A part of a punch 2 is formed thin to allow the easy transmission of the information on the crack generated in the work 5 to the punch 2. The work crack state from the work 5 is detected by a crack generating detecting means 6. The crack detection signal is converted and processed by amplification, etc., to the signal form to allow the easy decision of the crack generation state in a signal processing means 7. Whether the crack is generated in the work 5 or not is decided by a deciding means 8 based on the signal outputted from the signal means 7. The local crack generated at the time of working is detected in the real time at the time of molding in such a manner. The inspection stage for removing defective articles by a visual inspection is eliminated from the working line in such a manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of Industry] = 4] The present invention provides a punch with a built-in crack detection section. - In more detail, the present invention relates to a press device in which a bonder has a built-in crack detection section that detects cracks in a product in real time during product processing.

[Prior art and its problems]

Conventionally, in the press processing of B1NOS molded products, cracks have occurred in the press molded products due to local deviation loads, fluctuations in material properties, etc. during product processing, resulting in defective products.

These defective products were discovered and removed by skilled inspection or visual inspection after the molding process. For this reason, inspection I was required on the processing line, resulting in poor processing efficiency (2), which increased costs, and furthermore, inspection was only a post-processing process and could not prevent the occurrence of cracks.

As a method to solve this problem of the conventional technology, an acoustic emission sensor is provided to detect the initial deformation of the workpiece material before cracking occurs, and based on the detection of the initial deformation, the machine is stopped to prevent cracking. “Bunnos molded product crack prevention device 1” that prevents
JP-A-60-427500) has been proposed. Second
As shown in the figure, in this apparatus, an acoustic emission sensor (hereinafter referred to as AE sensor) 106 is attached within a die 103 in contact with a workpiece 105. The sensor 106 is connected to the main amplifier MA via a preamplifier PA and a filter FT, and is connected to a determination unit 108.
determines whether or not there is initial deformation that occurs in the workpiece 105 before cracking, based on the signal from the main amplifier MA. When the press machine 101 operates, the sensor 106 also operates.

When the workpiece 105 undergoes initial deformation before cracking occurs, the determination unit 108 determines the initial deformation, and either the control unit 109 or the press machine 101 stops operating. It is said that this will prevent the occurrence of cracks during Putos molding.

However, in this device, the sensor 106 is
1. Maybe that sensor is the workpiece 105
in direct contact with. Therefore, the AE multiplied signal due to the contact between the workpiece 105, the sensor 106, and the die 103 is preferentially detected, and it is difficult to detect the AE multiplied signal due to the initial deformation immediately before cracking occurs. Further, the portion where the crack occurs is the portion of the workpiece 105 that is pushed into the die gap by the punch 102. Therefore, the installation position of the sensor 10G is far from the crack occurrence location, and the AE multiplied signal sensor 106 due to the initial deformation before the crack occurrence.
Since the signal is attenuated during propagation, the detection efficiency also decreases.

Furthermore, since most of the AE multiplied signal levels associated with the initial deformation before cracking are weak, there is a drawback in that reliability is poor for determining cracks.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a press machine that can accurately detect cracks that occur during press forming of a molded product in real time and with high precision.

The present inventors have focused on the following regarding the problems of the prior art described above. That is, first, we focused only on the occurrence of cracks because, while the AE multiplied signal that occurs in response to the initial deformation before cracking is weak, the energy level released immediately after cracking is significantly higher. Next, since this crack occurs around the part of the material being worked that is in contact with the punch, a crack detection part is placed inside the punch at the bottom dead center of processing and the part included in the die cavity. It was to be. Furthermore, in order to efficiently propagate the energy and signals (information) emitted from the crack occurrence area to the crack detection area without spreading loss or attenuation, the part included in the die cavity of the punch is actively used. The walls were made thinner and the inside was hollow.

According to J2, when a crack occurs in the workpiece processed by a press machine, the abnormal signal generated at that time can be detected in real time and with high precision during molding, and the presence or absence of cracks can be determined. We have developed a press device that can be used accurately.

[Description of the first invention] Composition of the invention Press device 1 having a built-in crack detection part in the tool of the first invention
As shown in FIG. 1, the press is made up of a punch 2, a die 3, and a wrinkle holding plate 4, and a workpiece 5 is placed between the die 3 and the wrinkle holding plate 4 for press working. /s device, wherein the punch 2 has a hollow part, and at least a part of the part corresponding to the punch cavity is formed with a thin wall,
Transmitting the passion for cracks that occur in the workpiece to the punch (1
, and a crack occurrence detection means 6 disposed in the thin wall portion of the punch 2 for detecting a machining crack state from the workpiece 5, and a crack detection signal outputted from the crack occurrence detection means 6. A signal processing means 7 that converts and processes the signal into a signal format that makes it easy to determine the state of crack occurrence through amplification, etc., and determines whether cracks have occurred in the workpiece based on the signal output from the signal processing means 7. The present invention is characterized in that it has a determining means 8 for detecting local cracks that occur during the process of forming the mold in real time.

Function of the Invention The press device of the present invention operates after the press device 1 is activated and collides with and contacts the workpiece 5 which is sandwiched between the punch 2 or the die 3 and the holding plate 4. , the crack occurrence detection means 6 is activated in synchronization with this. If a crack occurs in the workpiece 5 during the forming process, a high level of energy (not shown) is released due to this crack. This high 1. - The energy of the bell changes into vibration, sound, elastic deformation of the tool, etc., and is transmitted to the crack occurrence detection means 6 as crack occurrence information (signal). The crack occurrence detection means 6 immediately detects the information (signal) of this crack occurrence. This detection signal is amplified by the signal processing means 7 and converted and processed into a signal form that makes it easy to determine the state of crack occurrence. Furthermore, the determining means 8 determines whether or not cracks have occurred in the workpiece 5 based on the signal output from the signal processing means 7.

Effects of the Invention The press apparatus of the present invention is capable of accurately detecting shear cracks that occur during processing of a press-formed product in real time and with high precision.

Additionally, if a crack occurs in the workpiece, it can be detected in real time and with high precision.
The conventional inspection process for removing defective products by visual inspection can be eliminated from the processing line.

[Description of Second Invention] Below, an invention that further improves the speech style of the first invention will be described as a second invention.

In the press device of the present invention, the punch has a hollow part inside, and at least a part of the part corresponding to the die cavity is formed with a thin wall to prevent cracks occurring in the workpiece from occurring in the punch. It is formed into a structure that is easy to transmit.

Regarding the shape and material of this punch, it is possible to use the conventional plate forming tool (punch) as is, or as mentioned above, the bonder has a hollow interior to provide a crack detection part. (hollow part). When providing a cavity, the thickness of the punch must be taken into account, or the thickness of the punch may be actively reduced to the extent that a sufficient practical strength level is ensured. Further, punches that are designed and manufactured from the beginning as tools having a cavity in consideration of weight reduction and ease of transportation can also be used with the cavity as is. In addition, if the wall thickness of the punch having the cavity may impair signal propagation, the surface of the punch cavity may be thinned toward the outer surface of the punch without impairing the practical strength level, and the crack detection section may be thinned. You can also attach it.

Further, the crack occurrence detection section can be installed by digging only the area and arranging the crack occurrence detection means, and furthermore, it is also possible to arrange the crack occurrence detection means in the dug portion and burying the core.

Further, the crack occurrence detection means is disposed in the thin wall portion of the punch, and detects the state of machining cracks from the workpiece. The crack occurrence detection means is for detecting machining crack conditions such as energy released in response to crack occurrence, vibration, and abnormal deformation behavior of the tool. It is appropriate to use something that generates voltage or something that causes voltage changes as the tool deforms, such as a strain gauge.

The shape and dimensions of the crack occurrence detection section must be suitable for placement within the punch. For example, since the detecting section of a sensor used as a crack occurrence detecting section usually has a planar shape, it is preferable that the punch cavity is also formed in a planar shape. In this way, if a sufficient area is not secured for the portion to be formed into a planar shape, a sensor with a smaller size is adopted.

A specific structural example of the arrangement structure of the AE sensor in the cavity inside the punch will be explained using FIGS. 3(a) to 3(C).

The first concrete structure example is as shown in FIG.
1 is fixed. However, if it is fixed with adhesive in this way, there is a risk that maintenance will be hindered. The second specific structural example is a structure in which the AE sensor B1 is fixed by a holder B4, as shown in FIG. 3 (1). In this case, in order to ensure a sufficient contact area between the AE sensor B1 and the inner surface of the punch line 3, it is necessary to sufficiently supply a propagation medium B5 such as vaseline or grease between the two. In addition, even if the punch B3 has a hollow part, if the punch bottom dead center (the wall thickness is considerably thick to the surface),
As shown in FIG. 3(C) as a third specific structural example,
The inner surface of punch C3 has a practical strength of 1. The structure is such that the bell is dug down to the extent that it will not be damaged, the AE sensor C1 is inserted there, and the holder C4 is fixed from above. Note that in the second and third specific structural examples, this holder 84,
When fixing with C4, apply pressure from above to ensure sufficient contact area between the AE center Bl, CI and the inner surface of punch B3, C3, and to prevent AE sensor from getting rash in the holder. Good. Figure 3 (l) and (C
), springs B6 and C6 are placed inside holders B4 and C4.
Insert it and press it with B7 and C7 from the -L part to achieve pressurization. The pressing force at this time is 0.2
If the diameter is more than kgf/mu2 or the diameter is after φ17mm+iij, there will be no performance problem even if a load of about 2 kgf is applied from the top. Further, the AE sensor or the AE sensor holder may be provided with a threaded portion, and the structure may be such that the AE sensor or the AE sensor holder is provided with a threaded portion and is screwed into the seven-pronged portion of the punch.

In addition, in the case of a strain gauge, it is best to attach the hollow part inside the punch by polishing the part well and gluing it directly with a special adhesive.

In addition, since vibration is expected to be propagated to the strain cage due to the driving of the punch, a gauge terminal is installed near the strain gauge, and the lead wire of the strain gauge is connected to the signal processing section by extending a vinyl-coated lead wire from the gauge terminal. It's good to do that. Furthermore, in order to prevent the strain gauge from absorbing moisture, it is preferable to apply a coating agent to the upper part of the strain cage and the gauge terminals and fix them.

In addition, the crack occurrence detection means is, in principle, disposed in a hollow portion within the punch at a portion included in the die cavity portion at the bottom dead center of the punch when the Punos device is operated.

However, when focusing on tool deformation behavior, the crack occurrence detection means can be installed in the hollow part of the punch even if the part is not included in the die cavity. It is possible to detect the state of machining cracks. That is, the prior art (Japanese Patent Application Laid-Open No. 60-247500)
The major difference is that in the present invention, the detection part is placed in contact with the workpiece, whereas in the present invention, there is no direct liquid between the workpiece and the detection part. By doing this, the information (signal) due to the gap of the workpiece sandwiched between the die and the wrinkle holding plate is not directly detected during molding.
It is possible to efficiently detect information (signals) due to the occurrence of cracks. In addition, since the detection part does not get rubbed or worn out due to the sliding of the workpiece, there is no need to replace the detection part, and compared to the conventional technology, the detection part can be used semi-permanently, causing damage and cracks. detection becomes possible.

Further, the signal processing means amplifies the crack detection signal output from the crack occurrence detection means, generates a pulse signal when there is an input signal equal to or higher than a preset internal threshold value, and so on. This is a means for converting and processing the signal into a signal format that makes it easy to determine the state of crack occurrence by outputting a voltage corresponding to the slope per zumbling time of the input signal, and further determining the frequency peak and energy density of the input signal. be. In addition, in order to remove the influence of external noise etc. from the signal/information detected by the crack occurrence detection means, the signal processing means includes a preamplifier for amplifying the signal and a crack occurrence detection means that simultaneously detects the signal/information. It is preferable that the device be equipped with a noise removing means such as a filter for removing low frequency external noise. Furthermore, if the low frequency external noise is sufficiently small compared to the crack occurrence signal, it is also appropriate to send the crack occurrence signal to the determination means without attenuating it with a filter, so the filter can be turned on or off. The type that can be used is preferable. Furthermore, even when the filter is turned on, it is assumed that the frequency of external noise varies, so it is better to use a filter that can cover several frequency bands.

Further, the determining means is a means for determining whether or not a crack has occurred in the workpiece based on the signal output from the signal processing means, and is a means for determining whether or not a crack has occurred in the workpiece. Sudden height 1.・It is used to judge the properties of Bell energy. As this determination means, for example, AE
When using a sensor as a crack detection means 2,
In order to judge the high/bell AE wave caused by the occurrence of a crack, a reference voltage is provided in the judgment means circuit, and if the reference voltage is exceeded by the input voltage, it is determined that a crack has occurred. . For example, when using a strain gauge as a means for detecting the occurrence of cracks, in order to determine the abnormal deformation behavior of the tool due to the occurrence of cracks, the signal/voltage input to the determination means at a certain period of time may be calculated using a differential coefficient. , and the discontinuous points can be determined as cracks. Note that these series of determinations can be performed using a computer.

In addition, the result determined by the determination means as described above is further provided with a control means to output a determination signal of the occurrence of a crack to the control means, and based on the determination signal, an alarm is issued with a buzzer, lamp, etc. It can be used to emit light or to stop the operation of the press equipment.

In addition, if a crack occurs in the pressurized stone by attaching the knee at several places in the hollow part of the AE seven rinser punch, it is also useful to predict whether the crack has occurred at the location of the workpiece. Ru. In other words, if a crack occurs at one location on the workpiece (A), the AE waves generated in response to the crack will be radiated and propagated in all directions of the punch.
If E7 rinsers are installed at several locations, all of the AE sensors will each detect the AE waves. However, since the AE wave is a type of wave phenomenon and has a certain propagation speed, a time difference occurs when the AE wave reaches each AE sensor. For example, since the AE sensor installed at the place closest to the crack occurrence point (-) will catch the AE wave as soon as possible, it will be the earliest to catch the AE signal, and it will also be possible to detect that a crack has occurred near the AE center. Can judge.Also,
Using the above time difference, by multiplying the propagation velocity by the time difference, a circle with a radius at a certain distance centered around each AE sensor is drawn. If you gradually increase the size of the lever circle, each of the 5 circles will intersect at a certain point. Since this intersection corresponds to the location where the crack occurs, it becomes possible to determine the location where the crack occurs with even greater accuracy. However, in this case, at least three AE sensors are required.

Furthermore, it goes without saying that by simultaneously disposing the AE sensor and the strain gauge in the cavity inside the punch and monitoring the detection information of both, the reliability of crack occurrence determination can be further improved.

Furthermore, when the B1NOS machine operates, it is expected that the punch will first collide with or come into contact with the workpiece sandwiched between the wrinkle holding plate and the die. At this time, too, there is a sudden release of high-level energy due to sound, vibration, etc., and some of this appears as AE waves. Therefore, it is appropriate to activate the crack occurrence detection section after the punch and the workpiece collide or come into contact with each other.

That is, an electric switch, a magnetic position detector, a non-contact type position detector such as an optical one is used as a limiter switch to check the operating status of the punch, and these switches are used to detect the collision/contact between the punch and the workpiece. It would be better to set it to the position where the crack detection part is turned on, so that when the switch is turned on, the crack occurrence detection part will also operate in synchronization with the switch.

The press device of the present invention has the above-mentioned features.
Not only can the effects of the first invention be achieved in the same way, but also the following effects can be achieved.

In other words, since it is possible to monitor abnormalities in forming tools, it is also useful for automatic management of press equipment. It also monitors whether the workpiece material is easily broken, which is useful for quality control of the workpiece material.

In addition, in the prior art Japanese Patent Application Laid-open No. 60-247500, the crack detection part must be in contact with the workpiece, whereas
The only difference in the present invention is that the detection part is not in direct contact with the workpiece. Therefore, the detection part is not rubbed or worn out by the edges of the workpiece, so there is no need to replace the detection part, and compared to JP-A No. 60-247500,
It is possible to use semi-permanent detection parts and detect cracks.

〔Example〕

The present invention will be explained in detail below.

First Embodiment The press apparatus of the first embodiment of the present invention is shown in FIGS. 4 and 5.
This will be explained using figures.

As shown in FIG. 4, the press apparatus @ 11 of this embodiment includes a punch 21, a die 31, a wrinkle pressing plate 41, etc., a crack occurrence detection means 61, a signal processing means 71, and a determining means 81.
and a control means 91.

The punch 21 is a spherical head-shaped molding tool with a diameter of 50 mm and a single ball R50, and is hollow inside and has a wall thickness of 10 mm. Further, the AE sensor 611 constituting the crack generation means 61
The apex part to which it is attached is formed into a flat shape. The punch 21 is attached to a double-acting hydraulic cylinder for punches (not shown) at the bottom of the press device 11 and is screwed to the punch holder, which is a punch holder. When the punch 21 rises, the workpiece 51 is It is pushed into the die cavity of the die 31 and molded into a desired shape.

The die 31 has a die hole size of 60 mm in diameter and a shoulder R5.
A punch 21 is attached to a hinged die holder (not shown) located at the top of the press device 11.
The workpiece 51 is fixed by screws so as to be concentric with the wrinkle press plate 41, and the workpiece 51 is sandwiched by the rise of the wrinkle presser plate 41, and the workpiece 51 is shaped by the rise of the punch 21.

The wrinkle pressing plate 41 is attached to the punch 11 by fitting into a wrinkle pressing guide attached to the lower part of the prunos device 11.
It is arranged so as to be concentric with the dice 31. This wrinkle holding plate 41 is used to hold the workpiece 51 placed on the plate 41.
is pressed against the die 31 by the rising of the scattering plate 41,
This method suppresses wrinkles that occur in the workpiece during molding, and it is also possible to perform bead forming that simultaneously suppresses the warp surface distortion that occurs in press-formed products.

The crack occurrence detection means 61 consists of a chip-type AE sensor 611 of approximately 1.5 mm x 4 mm, and is attached to the flat surface of the apex of the hollow portion of the hollow punch 21 with instant adhesive (
The die 31, punch 21, wrinkle presser plate 4
It is arranged on the same concentric axis as 1. Furthermore, Vaseline is applied around the AE set 611, and the AE set 611 is
It is fixed with cured resin from the 1F section. Thereby, a sufficient contact area with the punch 21 is ensured.

In this embodiment, the position of the shear crack that occurs in the workpiece 51 during molding is on the inner circumference of the die cavity centered on the punch 21.

The signal processing means 71 includes a preamplifier 711 and a filter 7.
12, a main amplifier 713, and a signal processing section 714. The preamplifier 711 is connected to the AE sensor 61N, amplifies the crack detection signal output from the AE sensor 611, and outputs the amplified signal. A filter 712 is connected to the preamplifier 711 and is connected to the preamplifier 711.
Low frequency external noise 2 is removed from the amplified signal output from 1, and a cracking state signal is output. Main amplifier 713
is connected to the filter 712, and the filter 712
The amplified signal is amplified and the amplified signal is output.

The signal processing unit 714 is connected to the main amplifier 713, receives the signal output from the main amplifier 713, and generates a pulse signal when the input signal exceeds a reference voltage around a preset sampling time. , the pulse signals are counted. Then, the count value of is converted into a voltage, and the converted voltage is output.

The determining means 81 includes the signal processing section 7 of the signal processing means 71.
14, and monitors a signal corresponding to the machining state expressed by the converted voltage output from the signal processing section 714 during press molding to determine whether or not a crack has occurred in the workpiece 21.

The determination is made in such a way that it is determined that a crack has occurred when a predetermined (predetermined) level is exceeded, and a signal is output to a control section 91 connected to the determination section 81.

The control means 91 is connected to the determination means 81 and stops the crop of the press machine 11 when it receives a determination signal from the determination means 81 indicating the occurrence of cracking, and provides an alarm consisting of an alarm lamp. 911, so that if a crack occurs in the workpiece 51, the operator is immediately notified.

Further, the punch device 11 is provided with a limiter switch, and the limiter switch is connected to the punch 2.
1 or the workpiece 51 is arranged so as to emit a signal at a position where it collides or contacts with the workpiece 51. Then, the AE sensor 611 is
A circuit is constructed to synchronize with the limiter switch, and is configured to operate immediately after the punch 21 constituting the press device 21 collides with/contacts the workpiece 51.

The operation of the press apparatus of the first embodiment having the above configuration will be explained below.

First, the workpiece 51 is placed on the die 31, and the workpiece 51 is held between the wrinkle presser plate 41 and the die 31.

Next, the press machine 11 is activated and the punch 21 starts the forming operation. Then, immediately after the punch 21 comes into contact with the workpiece 51, detection by the AE sensor 611 is started in synchronization with this. The AE wave detected by the AE sensor 611 is sent to the preamplifier 7 connected to the AE sensor 611.
After being preamplified by 11, low frequency external noise is removed by filter 712. The AE multiplied signal that has passed through the filter 712 is further amplified by the main amplifier 713 connected to the filter, and then sent to the signal processing section 7
Sent to 14th. The signal processing unit 714 receives the AE multiplied signal from the main amplifier 713, generates a pulse signal when it exceeds the reference voltage within a preset sampling time, and converts the pulse signal to 1-. The count value generated by the signal processing section 714 is converted into a voltage and sent to the determination means 81. The determining means 81 monitors the count value received from the signal processing section 714 during press molding, determines that a crack has occurred when the count value exceeds a preset predetermined number of 1-1 novels, and connects to the determining means 81. A signal is output to the size control means 91 that is being controlled.

FIG. 5 shows Table 1. Changes in the cumulative number of AE multiplied signals when a crack detection signal is detected. The diagram shows the diagram. At this time, the cumulative number is determined by the signal processing means 7 at the time of molding in the determination means 81.
This value is obtained by sequentially accumulating the count values output from 1, and FIG. 5 shows the results of measuring the changes. Here, it is determined that cracking has occurred when the cumulative number of AE multiplied signals reaches 100. The figure also shows the actual forming load.

When the determination means 81 determines that a crack has occurred, a signal indicating the determination result is sent to the sub-means 91, and the control means 9
1 alarm lamp 911 flashes.

According to the first embodiment, the workpiece 5 which is being press-formed
It is possible to detect the occurrence of cracks in 1 in real time during molding, and without picking up noise caused by the movement of the workpiece 51 with the die 31 or the wrinkle presser plate 41. Further, if it is determined that cracking has occurred, the control means 91
When the lamp 911 flashes, the bus 1/bus device 11 immediately
Since the process can be stopped, it is possible to eliminate the need for visual inspection of defective products by inspectors after the fact. moreover,
Since the AE sensor 611 is not in direct contact with the workpiece 51, the AE sensor 611 is not rubbed against the workpiece 51 and is worn out, allowing the AE sensor 611 to semi-permanently detect the occurrence of cracks.

Modification Example 1 In the first embodiment, cracks in the workpiece were determined by comparing the cumulative number of AE multiplied signals when a crack detection signal was detected with a preset cumulative number (reference value). Another method is to simply compare the count value with a reference value and determine that cracking has occurred if the count value exceeds the reference value. this is,
In the first embodiment, when the cumulative number exceeds the reference value,
Or, while it is a comprehensive judgment up to the end of molding,
Judgment based on count values is a method of sequential judgment during molding. By doing this, it is not only possible to determine cracks based on the AE multiplied signal of the high level energy released when cracks occur, but also to determine whether there is an abnormal collision between the workpiece and the punch before cracks occur. It is also useful for operation management.

Moreover, the presence or absence of cracking can be determined by comparing the variation pattern of the cumulative number with a pattern stored in advance in the determining means. By doing this, the cumulative number may gradually increase due to noise that cannot be removed by the filter, and may exceed the reference value. The gradual increase trend and the ward υ1 as a sudden increase in the cumulative number
,1 +,, crack occurrence can be determined with even higher accuracy.

Further, in the first embodiment, an alarm lamp is used as the control means, or an alarm means such as an alarm buzzer may be used. Further, the control means 91 can be connected to the press device 11 to directly stop the operation of the press device 11.

Second Embodiment A BUNOS device according to a second embodiment of the present invention will be explained with reference to FIGS. 6 and 7, focusing on the differences from the first embodiment.

As shown in FIG. 6, the press device 12 of this embodiment includes a punch 22, a die 32, a wrinkle pressing plate 42, a crack occurrence detection means 62, a signal processing means 72, and a determining means 82.
and a control means 92.

The punch 22 is a spherical head-shaped molding tool with a diameter of 50 mm and a ball R50, and is hollow inside and has a wall thickness of 10 mm. In addition, a strain gauge 621 constituting the crack generation means 62
The apex part to which it is attached is formed into a flat shape. The punch 22 pushes the workpiece 52 into the die cavity of the die 32 and forms it into a desired shape.

The die 32 has a die hole size of 60 mm in diameter and a shoulder R5.
The workpiece 52 is sandwiched by the rise of the wrinkle presser plate 42, and the workpiece 52 is held by the rise of the punch 22.
Mold 2.

The wrinkle pressing plate 42 is a workpiece 52 placed on the plate 42.
is pressed against the die 32 by the rising of the scattering plate 42 i,
f. It suppresses wrinkles that occur in the workpiece during molding, and also suppresses surface distortion that occurs in press-formed products, making it possible to perform one-step molding.

The crack occurrence detection means 62 consists of a strain gauge 621 of about 4.2 mm x 2.8 mm, and is fixed to the flat apex portion of the cavity of the hollow punch 22 with an instant adhesive. In the apparatus of this embodiment, the position of the crack that occurs in the workpiece 52 during molding is on the inner circumference of the die cavity centered on the punch 22.

The signal processing means 72 includes a dynamic strain meter 721 and a signal processing circuit 722. The dynamic strain meter 721 is a strain gauge 62
1, and removes low frequency noise from the crack detection signal output from the strain b gauge 621, amplifies it, and outputs the amplified signal. The signal processing circuit 722 includes the dynamic strain meter 72
1, converts the amplified signal output from the dynamic strain meter 721 into a differential coefficient, and outputs it as a processing state signal.

The determining means 82 is connected to the signal processing circuit 722 of the signal processing means 72, and monitors the processing state signal outputted from the signal processing circuit 722 during press forming to determine whether cracks have occurred in the workpiece 52. Determine if it is true or not. Note that this determination is made when it is detected that the voltage of the machining state signal output from the signal processing circuit 722 changes discontinuously from positive to negative or from negative to positive, and the determination unit determines that a crack has occurred. A signal is output to a control section 92 connected to the control section 82.

The control means 92 is connected to the determination means 82 and stops the operation of the press device 12 when it receives a determination signal indicating the occurrence of cracking from the determination means 82, and has an alarm section 921 consisting of an alarm buzzer. Therefore, if a crack occurs in the workpiece 51, the operator is immediately notified.

Note that the press device 12 is connected to the strain gauge 6 by a synchronous circuit.
21, and is configured so that the strain gauge 622 starts detecting at the same time the punch 22 is operated by the press machine 12.

The operation of the press apparatus of the second embodiment having the above configuration will be explained below.

First, the workpiece 52 is placed on the die 32, and the workpiece 52 is held between the wrinkle presser plate 42 and the die 32.

Next, when the punch machine 12 is activated and the punch 22 starts a forming operation, detection by the strain gauge 621 is started in synchronization with this. When a crack occurs in the workpiece 52, the forming load of the punch 22 suddenly decreases due to this crack? = Therefore, the strain gauge 621 detects the sudden deformation behavior that occurs. The detection signal is amplified after low frequency noise is removed by a dynamic strain meter 721 and sent to a signal processing circuit 722 . FIG. 7 shows the results of recording detection signals output from the signal processing circuit 722 during molding. The figure also shows the actual molding load. As a result, the signal processing circuit 722
immediately converts the detection signal into a differential coefficient within a set sampling time and outputs it to the determining means 82. Furthermore, the determining means 82 determines whether a crack has occurred in the workpiece 52 by detecting that the differential coefficient changes discontinuously from plus to minus or from minus to plus, and outputs this determination signal. The control unit 92 or the press device 1
Stop the operation of 2.

According to the second embodiment, the generation of cracks in the press-molded workpiece is detected and the BUNOS device is stopped accordingly, so the visual inspection process for removing defective products can be omitted. I can do it. Furthermore, even if there are no cracks in the workpiece, abnormal deformation behavior due to damage to the punch can be detected, so the operating status of the press machine can be managed.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram with some exceptions showing the basic principle of the present invention, Figure 2 is a block diagram of a conventional press molded product crack prevention device, and Figure 3 is the basic arrangement structure of the AE sensor. 4 and 5 show the first embodiment, FIG. 4 is a block diagram of the press device, and FIG. 5 is a diagram showing changes in the cumulative number of AE multiplied signals in the determination means. 6 and 7 show the second embodiment, FIG. 6 is a block diagram showing the configuration of the embodiment of the present invention, and FIG. 7 is a diagram showing changes in the detection signal in the signal processing means. 1, 11, 12 2.21.22 3.31.32 4.41.42 5.51.52 6.61.62 7.71.72 8.8 l, 82 91, 92 ... Press device・... Bonder... Die... Wrinkle holding plate... Workpiece material... Crack occurrence detection means... Signal processing means... Judgment means control means

Claims (1)

[Claims] (1) In a press device that includes a punch, a die, and a wrinkle holding plate and performs pressing by placing a workpiece between the die and the wrinkle holding plate, the punch has a hollow portion and a die cavity. At least a part of the portion corresponding to the workpiece is formed to have a thin wall to facilitate transmitting information about cracks occurring in the workpiece to the punch, and is disposed in the thin-walled portion of the punch to prevent cracking from the workpiece. A crack occurrence detection means for detecting a machining crack state; a signal processing means for amplifying a crack detection signal output from the crack occurrence detection means to convert and process it into a signal form that makes it easy to determine a crack occurrence state; and a determination means for determining whether cracks have occurred in the workpiece based on the signal output from the processing means, and detects local cracks that occur during press processing in real time during forming processing. A press device having a built-in crack detection part in a tool, characterized in that the tool is configured to do so.