JP4536620B2 - Defect determination method and defect determination device for press-worked product, and defect determination method and defect determination device for press-work mold - Google Patents

Description

  The present invention relates to a pressed product defect determination method, a defect determination device, and a pressed metal mold for performing defect determination on a pressed product when performing ductile press processing of the material by pressing at least a pair of molds against the material. The present invention relates to a mold defect determination method and a defect determination apparatus.

  Conventionally, a method as disclosed in Patent Document 1 is known as a method of diagnosing the presence / absence of an abnormality of an object to be measured using an AE signal. The present invention simplifies the AE data obtained based on the AE signal detected from the object to be measured based on the peak data of the AE data, and diagnoses the presence or absence of abnormality of the object to be measured using the processed and deformed data. Yes.

However, in the ductile press as in the present invention, as shown in FIG. 3 (b), a signal due to cracking or the like is generated in the acoustic signal between the bottom dead centers after contact when processing a defective product. However, as shown in FIGS. 3A and 3B, a huge acoustic signal is generated from the material during processing regardless of whether there is a normal failure. It was difficult to accurately diagnose the presence or absence.
JP 2002-107347 A

  In view of such a conventional situation, the present invention provides a defect determination method and a defect determination apparatus for a pressed product that can reliably and accurately determine the defect of a pressed product in real time in a state where the press machine is operated. It is another object of the present invention to provide a defect determination method and a defect determination apparatus for press working dies.

  In order to achieve the above object, the feature of the method for judging a defect of a press-worked product according to the present invention is that the defect judgment of a press-worked product in the case of performing ductile press work of this material by pressing at least a pair of molds against the material. A method for receiving an acoustic signal generated at the time of deformation, approximating the measured waveform of the acoustic signal by polynomial approximation, calculating a correction formula of the waveform of the acoustic signal, and correcting the measured acoustic signal based on the correction formula Then, a correction waveform is created, and the defect determination of the pressed product is performed using the correction waveform.

Here, in a so-called crank press machine, the relationship between the crank angle α and the stroke amount S is expressed by the following equation shown in FIG. Here, S _Max refers to the maximum stroke amount.
_{S = S Max × (1-} cos (α))

Further, in the relationship between the crank angle and the displacement amount, the displacement amount d is expressed by the following equation and is expressed in a trigonometric function as shown in FIG.
d = S × (α−1) −Sα
In the above relationship, as shown in FIG. 2 (c), when FIG. 2 (b) is enlarged between certain crank angles, the above equation is expressed as a substantially straight line. The crank angle can be converted into time, and the above equation can be regarded as a displacement equation representing the amount of displacement per unit time.

  FIG. 3 is a graph showing the relationship between the waveform of the acoustic signal after filtering and detection and the displacement equation indicating the displacement per unit time shown in FIG. As shown in the figure, between the bottom dead center after the mold contacts the material, the displacement equation and the acoustic signal have a correlation in which the amplitude of the acoustic signal decreases as the displacement amount decreases. It became clear. As shown in the figure, it is possible to identify the sound signal generated at the time of defect and determine the defect of the pressed product by eliminating the influence of the sound signal generated constantly by the difference from the displacement formula. There was found.

  In addition, it is understood that not only the difference from the displacement equation of the amplitude value of the acoustic signal, but also the distribution width and area of the acoustic signal increase, and the press processed product also depends on the difference from the displacement equation of the distribution width and area of the acoustic signal. The conclusion was reached that it was possible to determine the failure.

  In the above feature, as shown in FIG. 4, it has been found that the correction equation for the waveform of the acoustic signal obtained by polynomial approximation has the same relationship as the relationship between the displacement equation and the acoustic signal. And it turned out that it is possible to determine the defect of a press work product with the correction waveform obtained by correcting the waveform of the acoustic signal measured by the correction formula. The defect determination may be performed by any one of an amplitude value, a distribution width value, or an area value, or by a combination of all or any of these values.

  Further, in order to achieve the above object, the feature of the pressed product defect determination device according to the present invention is a sensor for receiving the acoustic signal, a proximity detecting means for detecting a proximity state of the dies, In conjunction with the proximity detecting means, a gate timer for detecting an acoustic signal generated when the material is deformed among signals received by the sensor, and calculating a correction formula for the acoustic signal waveform by polynomial approximation of the acoustic signal waveform. Correction formula calculation means, correction waveform creation means for correcting the acoustic signal measured based on the correction formula to create a correction waveform, memory means for storing a reference value for comparison, and features extracted from the correction waveform Comparing means for comparing the amount with the reference value, and alarm means for notifying that the pressed product is defective when the feature value exceeds the reference value by the comparing means. In the door.

  Here, the “proximity detecting means” can be constituted by, for example, a press control unit capable of detecting a crank angle. The “feature amount” refers to the amplitude, distribution width, area, or the like of the acoustic signal, and the “reference value” includes a reference difference and a reference correction waveform obtained as described above in addition to a constant. .

On the other hand, in order to achieve the above object, the defect determination method of the press working mold according to the present invention is characterized in that at least a pair of molds are pressed against the material to perform ductile press working of this material. A method for determining a defect of a mold, receiving an acoustic signal generated at the time of deformation, calculating a waveform correction equation of the acoustic signal by polynomial approximation of the measured waveform of the acoustic signal, and measuring the waveform based on the correction equation A correction waveform is created by correcting an acoustic signal, and a defect in the press working mold is determined based on the correction waveform.
In such a case, the defect determination may be performed based on any one of an amplitude value, a distribution width value, and an area value, or a combination of all or any of these values.
In order to achieve the above object, the defect determination device for a press working mold according to the present invention is characterized by a sensor for receiving the acoustic signal and a proximity detecting means for detecting a proximity state of the molds. In conjunction with this proximity detection means, a gate timer for detecting an acoustic signal generated when the material is deformed among signals received by the sensor, and calculating a correction formula for the acoustic signal waveform by polynomial approximation of the acoustic signal waveform A correction formula calculating means for correcting the acoustic signal measured based on the correction formula to create a correction waveform, a memory means for storing a reference value for comparison, and a correction waveform extracted from the correction waveform Comparing means for comparing the feature quantity with the reference value, and alarm means for notifying that the press mold is defective when the feature quantity exceeds the reference value by the comparing means. In the Rukoto.

  According to the feature of the defect determination method and the defect determination apparatus according to the present invention described above, the defect determination is performed based on at least an acoustic signal generated when the material is deformed. In addition, even if the processing is complicated, it is possible to reliably catch some of the defects that are difficult to detect visually and determine the defects.

  In addition, it is possible to more accurately evaluate the deterioration even when the mold has a relatively wide time width, such as when the mold is in contact with the material multiple times.

  Further, when the proximity means and the gate timer linked thereto are used, the acoustic signal can be sampled as much as possible to the acoustic signal generated when the material is deformed, and the disturbance element can be eliminated.

  Moreover, based on the press-deformed product defect determination method and the defect determination apparatus according to the present invention, it is possible to perform the press-processed product defect determination and the mold defect determination.

  Other objects, configurations, and effects of the present invention will become apparent from the following embodiments of the present invention.

Next, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view of a ductile press machine that is an object of the determination method according to the present invention. A press machine 1 shown in FIG. 1 is an apparatus that performs press processing of a material S by a crank mechanism 4. The crank mechanism 4 transmits the rotation of the motor controlled by the press control unit to the crankshaft 6 and moves the slide 2 up and down via the connection rod 7. A punch 2 a is attached to the slide 2, and a die 3 a that is paired with the punch 2 a is attached to the bolster 3.

  The press control unit monitors the crank angle α by the rotation of the motor, and serves as a trigger for a gate timer, which will be described later, that detects an acoustic signal at the time of deformation in which the material S is sandwiched and deformed between the punch 2a and the die 3a. That is, it also functions as a proximity detection means for detecting the proximity state of the punch 2a and the die 3a. The proximity detection means may be configured by attaching a proximity sensor and a corresponding proximity piece to the pair of molds 2 and 3. In this case, it is possible to simultaneously detect the intrusion of foreign matter between the material S and the molds 2 and 3, but in order to operate the gate timer more accurately, the crank angle is used as a trigger. Is desirable.

Further, an AE sensor 11 for receiving an acoustic signal generated when the material S is deformed is attached to a side portion of the die 3a. The AE sensor 11 can be attached not only to the die 3a but also to other parts such as the bolster 3 and the slide 2 side. In this embodiment, in order to make it easier to evaluate the deterioration of defective products, This AE sensor 11 is attached to the side.
Next, the relationship between the pressing process and the acoustic signal received by the AE sensor 11 will be described while comparing FIGS. 1 (a) to 1 (c) and FIGS. 5 (a) and 5 (b).

  The first signal group Q1 in FIG. 5A is a signal generated when the punch 2a contacts the material S after the slider descends from the top dead center as shown in FIG. After the contact, as shown in FIG. 5 (a), the second signal group P gradually increases in the brittle region of the material S, and then gradually reaches a peak at the bottom dead center with time in the ductile region. Decrease. This signal group P is an acoustic signal generated until the slide 2 reaches the bottom dead center after the punch 2a contacts the material S as shown in FIG. 1B, that is, an acoustic signal accompanying the deformation of the material S. The third signal group Q2 is an acoustic signal when the punch 2a leaves the material S after passing through the bottom dead center, that is, after processing.

The gate timer is actuated from time T0 triggered by the crank angle α detected by the press control unit reaching a certain angle, and an acoustic signal that does not include Q2 is detected between detection times T0 and T2. In this embodiment, the time T0 corresponds to a crank angle of 120 °, and the time T2 corresponds to a bottom dead center having a crank angle of 180 °, but is not limited to these values and may be appropriately changed depending on the processing conditions and the like. May be.
5C and 5D are graphs showing acoustic signals received in the case of a defective product. As shown in the figure, a portion protruding in the amplitude of the second group of signal groups P is generated. Of these protruding portions, a large protrusion in the vicinity of the bottom dead center is steadily generated even when processing a normal product, as shown in FIGS. On the other hand, the protruding portion appearing before that does not exist in FIGS. 5 (a) and 5 (b), and it has been confirmed by experiments by the inventors that this is an acoustic signal generated only when there is a defect such as a crack in press working. It was.

  In the present embodiment, as shown in FIG. 5, among the above-described acoustic signals, the second group of acoustic signals P is a measurement target, and the acoustic signals P in the ductile region of the material are further divided into a plurality of sections G1 to G3. The defective product is determined based on the difference areas A1 to A3 between the acoustic signal P and the displacement equation V in the sections G1 to G3. The sections G1 to G3 are formed by setting an arbitrary time based on the detection time T0. By using the difference from the displacement formula V, the difference between the normal and defective acoustic signals can be clarified, and a processing defect can be reliably captured.

  FIG. 6 is a block diagram of a defect determination apparatus used in the present embodiment. The acoustic signal received by the AE sensor 11 is filtered and detected via the filter unit 20 and then processed by the personal computer 30. The alarm means 60 includes a display 61 that displays the waveform of the acoustic signal and the evaluation result of the processed product, and an alarm device 62 that generates an alarm sound when a defective product occurs. The filter unit 20 includes a signal converter 21 with a sensitivity adjustment function for amplifying an acoustic signal received by the AE sensor 11, a high-pass filter 22 for noise removal, a low-pass filter 23, and a detection circuit 24 for extracting a positive signal. And. The sensitivity adjustment amplifier 18 sends a trigger signal to the gate timer 37 when the crank angle signal generated by the press control unit exceeds a certain angle.

  A processing procedure in the personal computer 30 will be described with reference to FIGS. 6 and 7. When the crank angle α is equal to or greater than a predetermined angle, the signal converter 13 sends a trigger signal (step S1), and the gate timer 37 is activated accordingly (step S2). The acoustic signal from the filter unit 20 is converted into a digital signal by the A / D converter 31 and sent to the comparison unit 35 via the difference calculation unit 40.

  The difference calculating means 40 calculates the difference between the displacement formula V stored in the displacement formula memory means 41 and the acoustic signal P. The displacement formula V is created by inputting machining conditions, machining time, and the like via the parameter input unit 35 in advance. Further, the difference calculating means 40 includes an integrating means 42, and the integrating means 42 calculates difference areas A 1 to A 3 between the displacement equation V and the acoustic signal P.

The processing in the comparing means 32 via the integrating means 42 is to obtain the difference areas A1 to A3 between the acoustic signal P and the displacement equation V in each of the sections G1 to 3 within the section times t0 to t3 (steps S3 to 5). ). Then, it is determined whether or not the difference areas A1 to A3 are larger than the reference values in the sections G1 to G3 stored in the memory means 33.
In the present embodiment, when at least one of the difference areas A1 to A3, which is the feature amount of the difference of the acoustic signal P, exceeds a predetermined reference value during the section time t0 to t3, an alarm indicating that the product is defective is issued. Issued by the alarm means 40 (step S7). When an alarm or the like is not generated, a message indicating that the processed product is normal is displayed via the display 41 (step S6).

  In addition, it is also possible to constitute the alarm for the occurrence of defective products in step S7 so that the alarm is generated only when at least two of the difference areas A1 to A3 exceed the reference value.

  In this embodiment, the defect determination is performed based on the difference area A. However, the difference value is not limited to the area value, and the defect determination can be similarly performed on the amplitude value and the distribution width value. Further, for example, as shown in FIG. 12, in addition to the integrating means 42, the difference calculating means 40 is provided with a path 43 and a distribution width calculating means 44 for calculating the difference between the amplitude value and the distribution width, and as shown in FIG. It is also possible to perform defect determination by a processing procedure in which each difference value is calculated in the section (steps S33 to S41) and compared with each reference value to give an alarm or the like (steps S42 and S43). However, in general, an acoustic signal at the time of a defect due to cracking has a long duration, so that the energy is large and the area value is large. However, the abnormality of the acoustic signal due to the mold structure has a large amplitude value but a small energy. For this reason, it is desirable from the viewpoint of accuracy to perform defect determination mainly based on the area value.

  Furthermore, these difference values can be appropriately combined to make a defect determination, and can be configured to issue a warning when one or more exceeds each reference value. The reference value means a value that is appropriately determined depending on the finished accuracy of a processed product obtained by the press working method.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, a correction formula is calculated based on the waveform of the acoustic signal within the inner section time of the received acoustic signal, and a defective product is determined based on the corrected waveform of the acoustic signal created by the correction formula. Of the determination apparatus 1 used in the present embodiment, the AE sensor 11, the filter unit 20, the alarm means 40, the proximity sensor 15 and the like are substantially the same as those in the first embodiment described above, but the configuration of the personal computer 30 is the same. Some are different.

  A processing procedure in the personal computer 30 will be described with reference to FIGS. 8 and 9. When the crank angle α is equal to or larger than the predetermined angle, the signal converter 13 sends a trigger signal (step S11), and the gate timer 37 is activated accordingly (step S12). The acoustic signal from the filter unit 20 is converted into a digital signal by the A / D converter 31. The acoustic signal converted into the digital signal is subjected to polynomial approximation of the acoustic signal by the correction formula calculating means 51 within the section times t0 to t3 set in advance via the parameter input unit 35, thereby calculating a correction formula W (step S13), and sends it to the correction waveform creating means 52.

  As shown in FIGS. 10, 11 (c) and (d), the correction waveform creating means 52 generates a correction waveform R of the received acoustic signal based on the calculated correction formula W (step S <b> 14). ). The generated correction waveform R is sent to the comparison unit 32 via the integration unit 53. By performing defect determination using the correction waveform R generated based on the correction formula W, the difference between the normal and defective acoustic signals can be clarified, and processing defects can be reliably captured.

The processing in the comparison means 32 through the integration means 53 calculates the areas of the correction waveform areas B1 to B3 of the correction waveforms in the sections G1 to 3 within the section times t0 to t3 (steps S15 to 17), and It is determined whether or not the corrected waveform areas B1 to B3 are larger than the reference values in the sections G1 to G3 stored in the memory means 33.
In the present embodiment, an alarm indicating that the product is defective is issued from the alarm means 40 when at least one of the area values, which are feature amounts of the correction waveform, exceeds a predetermined reference value during the section time t0 to t3. (Step S19). If an alarm or the like is not generated, a message indicating that the processed product is normal is displayed via the display 41 (step S18).

  Note that the punch replacement alarm in step S8 may be configured to generate an alarm only when at least two of the waveform areas exceed the reference value.

  In this embodiment, the defect determination is performed based on the waveform area B. However, the defect determination is not limited to the area value, and the defect determination can be similarly performed with respect to the amplitude value and the distribution width. Further, for example, as shown in FIG. 14, in addition to the integrating means 53, a path 54 and a distribution width calculating means 55 for calculating the difference between the amplitude value and the distribution width are provided, and as shown in FIG. Each value is calculated (steps S54 to 62), and compared with each reference value to give an alarm or the like (steps S63 and S64). However, since an acoustic signal at the time of failure due to cracking generally has a long duration, energy is large and an area value is also large. Therefore, it is desirable from the aspect of accuracy to perform defect determination mainly based on the area value.

  Further, these values can be combined as appropriate to make a failure determination, and a warning can be generated when one or more of the values exceed each reference value. The reference value means a value that is appropriately determined depending on the finished accuracy of a processed product obtained by the press working method.

Furthermore, the possibilities of other embodiments of the invention are listed.
In each of the above embodiments, a steel plate is used as the material S. However, the present invention may also be applied to press working of a resin material other than a metal plate other than a steel plate.

  In each of the embodiments described above, the defect determination is performed in the plurality of sections G1 to G3. However, it is also possible to determine within an arbitrary range without dividing the section. However, in terms of determination accuracy, it is preferable to perform determination by dividing into a plurality of sections.

  In each of the above-described embodiments, the defect determination method and the determination device for a press-processed product have been described. However, since the acoustic signal generated at the time of failure includes an acoustic signal due to the defect of the mold, it is possible to determine the defect of the mold at the same time as determining the defect of the pressed product. That is, the press-processed product defect determination method and determination apparatus can also be implemented as a press-work mold defect determination method and determination apparatus.

  In each of the above-described embodiments, a press machine using a crank mechanism has been described as an example. However, it is not limited to press working by a crank mechanism. For example, if a press working is performed by a mechanism that converts a rotational motion such as a cam press, a knuckle press, a link press, etc. into a linear motion, it is possible to determine the defect of the pressed product. Is possible.

  INDUSTRIAL APPLICABILITY The present invention can be used as a failure determination method and a failure determination device for any press-processed product that involves plastic deformation of a material such as bending or deep drawing. Further, it can be used as a defect determination method and a defect determination apparatus for a press working mold.

(A) is a state where the upper die is in contact with the material, (b) is between the top dead center and the bottom dead center of the crank, and (c) is the bottom dead center of the crank. It is a schematic sectional drawing which shows each of these states. (A) is a graph showing the relationship between the crank angle and the stroke, (b) is a graph showing the relationship between the crank angle and the displacement, and (c) is a graph enlarged in a certain section of (b). It is a graph which shows the acoustic signal after the detection in the press machine of FIG. 1, (a) shows the case where it is a normal process, (b) shows the case where it becomes a defect process, respectively. It is a graph which shows the relationship between the acoustic signal after a detection in the press machine of FIG. 1, the correction formula of an acoustic signal, and a correction waveform. It is a graph which shows the relationship between the acoustic signal after a detection in the press machine of FIG. 1, and the displacement type | formula of FIG.3 (c), (a) at the time of a normal product press work, (b) is the partial expansion of (a). , (C) shows a partial enlargement of (c) when pressing a defective product. It is a block diagram which shows 1st embodiment of the defect determination apparatus concerning this invention. It is a flowchart which shows the operation | movement in 1st embodiment of the defect determination apparatus concerning this invention. It is a block diagram which shows 2nd embodiment of the defect determination apparatus concerning this invention. It is a flowchart which shows operation | movement in 2nd embodiment of the defect determination apparatus concerning this invention. It is a graph which shows the relationship between the acoustic signal after a detection in 2nd embodiment of the defect determination apparatus concerning this invention, and a correction | amendment waveform, (a) is the acoustic signal before correction | amendment at the time of a press work of a normal product, (b). (A) shows a partial enlargement, (c) shows a correction waveform during pressing of a normal product, and (d) shows a partial enlargement of (c). It is a graph equivalent to FIG. 10 which shows the relationship between the acoustic signal at the time of the defect after a detection in 2nd embodiment of the defect determination apparatus concerning this invention, and a correction waveform. It is a block diagram which shows another embodiment of 1st embodiment of the defect determination apparatus concerning this invention. It is a flowchart which shows operation | movement in another embodiment of 1st embodiment of the defect determination apparatus concerning this invention. It is a block diagram which shows another embodiment of 2nd embodiment of the defect determination apparatus concerning this invention. It is a flowchart which shows the operation | movement in another embodiment of 2nd embodiment of the defect determination apparatus concerning this invention.

Explanation of symbols

1: Press processing machine, 2: Slide (upper die), 2a: Punch, 3: Bolster (lower die) 3a: Die, 4: Crank mechanism, 5: Flywheel, 6: Crankshaft, 7: Connection rod 10: 11: AE sensor 12: Press control unit (proximity detection means) 13: Signal converter 20: Filter unit 21: Signal converter with sensitivity adjustment function 22: High-pass filter 23: Low-pass filter , 24: detection circuit, 30: personal computer, 31: A / D converter, 32: comparison means, 33: memory means, 34: gate timer, 35: parameter input unit, 40: difference calculation means, 41: displacement memory Means: 42: integration means, 43: path, 44: distribution width calculation means, 50 :, 51: correction formula calculation means, 52: correction waveform creation means, 53: integration means, 4: path, 55: distribution width calculation means, 60: alarm means, 61: display, 62: alarm device, S: material, P: waveform to be measured (acoustic signal), R: correction waveform, V: displacement type, W : Correction equation, α: crank angle, G1-3: gate, A: difference area, B: correction waveform area

Claims (6)

A method for determining a defect in a pressed product when performing ductile pressing of a material by pressing at least a pair of molds against the material, receiving an acoustic signal generated during deformation, and measuring the waveform of the acoustic signal measured Press processing that calculates a correction formula for the waveform of the acoustic signal by approximating the polynomial, corrects the acoustic signal measured based on the correction formula, creates a correction waveform, and determines a defect in the pressed product using the correction waveform Defect judgment method of goods. The defect determination method for a pressed product according to claim 1, wherein the defect determination is performed by any one of an amplitude value, a distribution width value, and an area value, or by a combination of all or any of these values. 3. A pressed product defect determination apparatus for use in the pressed product defect determination method according to claim 1 or 2, wherein a sensor for receiving the acoustic signal and a proximity for detecting a proximity state of the molds. A detection unit, a gate timer that detects an acoustic signal generated when the material is deformed among signals received by the sensor in conjunction with the proximity detection unit, and correction of the acoustic signal waveform by polynomial approximation of the acoustic signal waveform From the correction waveform, a correction formula calculation means for calculating a formula, a correction waveform creation means for correcting the acoustic signal measured based on the correction formula to create a correction waveform, a memory means for storing a reference value for comparison, and the correction waveform Comparing means for comparing the extracted feature quantity with the reference value, and an alarm for notifying that the pressed product is defective when the feature quantity exceeds the reference value by the comparing means. Failure determining apparatus of pressed product that has and. A method for determining a defect of a press working mold when performing ductile press working of this material by pressing at least a pair of molds against the material, receiving an acoustic signal generated during deformation and measuring the waveform of the acoustic signal Is approximated by a polynomial to calculate a correction formula for the waveform of the acoustic signal, the acoustic signal measured based on the correction formula is corrected to create a correction waveform, and a defect in the press working mold is determined based on the corrected waveform. Defect judgment method for press working dies. The defect determination method for a press working die according to claim 4, wherein the defect determination is performed by any one of an amplitude value, a distribution width value, and an area value, or a combination of all or any of these values. 6. A press die determination device used in the press die determination method according to claim 4 or 5, wherein a sensor for receiving the acoustic signal and a proximity state of the dies are detected. A proximity detector, a gate timer for detecting an acoustic signal generated when the material is deformed among signals received by the sensor in conjunction with the proximity detector, and a waveform of the acoustic signal by approximating a waveform of the acoustic signal by a polynomial A correction formula calculating means for calculating the correction formula, a correction waveform generating means for correcting the acoustic signal measured based on the correction formula to create a correction waveform, a memory means for storing a reference value for comparison, and the correction Comparing means for comparing the feature value extracted from the waveform with the reference value, and when the feature value exceeds the reference value, the comparison means informs that the press mold is defective. Failure determination device for stamping die and a distribution means.

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