System for monitoring vibration response of metal flow in stamping process

Abstract

The present disclosure provides a system for monitoring a vibratory response of metal flow in a stamping process. A die for stamping a metal sheet includes: a first portion having a bead; the second part is provided with a concave channel; and at least one accelerometer, the at least one accelerometer being positioned adjacent to the concave channel. When a metal sheet is positioned between the first portion and the second portion, the first portion and the second portion are configured to engage together such that the bead cooperates with the concave channel to apply a blank retention force (BHF) to the metal sheet to clamp the metal sheet. The at least one accelerometer measures a time-domain parameter or profile or a frequency-domain parameter or profile during placement of the metal plate.

Description

Technical Field

[0001] The present disclosure relates to a system for monitoring the operation of a stamping process. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Because of the high force loading conditions present in some stamping operations, various mechanical elements of a press may be susceptible to premature end of life. For example, if it is estimated that a press will have a five-year life based on certain production levels of stamped parts, and one or more of the press components only have a one or two-year life, the components will prematurely end their life; this can result in significant downtime and loss of revenue. Premature end of life of press components may be particularly prevalent when an older press is reconfigured to perform stamping operations under forces greater than those considered in the original design parameters.

[0004] In addition, within the stamping process, when the metal sheet is initially formed, it is critical to maintain a consistent blank holding force (BHF) for each formed part. The BHF clamps the metal sheet around the edge of the part between the concave channel to be formed in one half of the die and the mating convex bead on the other half of the stamping die. During the forming process, the metal sheet is pulled through the clamping point. Changes in the BHF of the clamped metal sheet may occur due to several reasons including but not limited to accumulation, wear, pressure problems and material properties. These changes may cause parts to wrinkle, crack and incorrect size. Defective parts are usually not noticed until they have gone through the entire stamping process, which leads to excessive waste and delayed response to problems.

[0005] The present disclosure addresses challenges associated with the stamping process. Summary of the invention

[0006] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0007] In one form of the present disclosure, a die for stamping a metal sheet includes: a first portion having a convex bead; a second portion having a concave channel; and at least one accelerometer positioned adjacent to the concave channel. When a metal sheet is positioned between the first portion and the second portion, the first portion and the second portion are configured to be brought together such that the convex bead cooperates with the concave channel to apply a blank holding force (BHF) to the metal sheet to clamp the metal sheet. The at least one accelerometer measures a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal sheet.

[0008] In a variation of the die that may be implemented alone or in any combination: the first portion comprises a preformed convex shape and the second portion comprises a preformed concave shape; when the first portion and the second portion are brought together to clamp the metal sheet, a part having a shape defined by the preformed concave shape and the preformed convex shape is produced; the at least one accelerometer comprises a plurality of accelerometers positioned around the periphery of the concave channel; if the time domain parameter or profile or the frequency domain parameter or profile exceeds an upper limit, the BHF is excessive; if the time domain parameter or profile or the frequency domain parameter or profile is below a lower limit, the BHF is insufficient; the die further comprises a pillow frame to which the second portion is secured; the die further comprises at least one other accelerometer positioned on the pillow frame to measure the time domain parameter or profile or the frequency domain parameter or profile during placement of the metal sheet between the first portion and the second portion; and the at least one other accelerometer comprises a second plurality of accelerometers.

[0009] In another form, a die for stamping a metal sheet includes: a first portion having a bead; a second portion having a concave channel; a pillow frame to which the second portion is fixed; and at least one accelerometer positioned on the pillow frame. When a metal sheet is positioned between the first portion and the second portion, the first portion and the second portion are configured to be brought together so that the bead cooperates with the concave channel to apply a blank holding force (BHF) to the metal sheet to clamp the metal sheet. The at least one accelerometer measures a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal sheet.

[0010] In a variation of this mold that can be implemented alone or in any combination: the mold also includes at least one other accelerometer, the at least one other accelerometer is positioned near the concave channel to measure a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal sheet between the first part and the second part; the first part includes a preformed convex shape, and the second part includes a preformed concave shape; when the first part and the second part are brought together to clamp the metal sheet, a part having a shape defined by the preformed concave shape and the preformed convex shape is produced; wherein the at least one accelerometer includes a plurality of accelerometers positioned on the pillow frame; if the time domain parameter or profile or the frequency domain parameter or profile exceeds an upper limit, the BHF is excessive; and if the time domain parameter or profile and the frequency domain parameter or profile are below a lower limit, the BHF is insufficient.

[0011] In yet another form, a system for stamping a metal sheet includes: a first portion having a bead; a second portion having a concave channel; a pillow frame to which the second portion is fixed; a plurality of accelerometers, the plurality of accelerometers being positioned on at least the second portion and the pillow frame; and a processing unit in communication with the plurality of accelerometers, the first portion and the second portion being configured to be brought together when a metal sheet is positioned between the first portion and the second portion so that the bead cooperates with the concave channel to apply a blank holding force (BHF) to the metal sheet to clamp the metal sheet. The plurality of accelerometers measure a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal sheet, the time domain parameter or profile or the frequency domain parameter or profile being transmitted to the processing unit.

[0012] In a variation of this system that may be implemented alone or in any combination: the first portion comprises a preformed convex shape and the second portion comprises a preformed concave shape, and wherein when the first portion and the second portion are brought together to clamp the metal sheet, a part having a shape defined by the preformed concave shape and the preformed convex shape is produced; if the time domain parameter or profile or the frequency domain parameter or profile exceeds an upper limit, the BHF is excessive; and if the time domain parameter or profile or the frequency domain parameter or profile is below a lower limit, the BHF is insufficient.

[0013] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order that the present disclosure may be better understood, various forms of the present disclosure will now be described by way of example with reference to the accompanying drawings, in which:

[0015] Figure 1 A press for stamping according to the principles of the present disclosure is shown;

[0016] Figure 2 shows the lower portion of a press according to the principles of the present disclosure;

[0017] Figure 3 shows various stages of a stamping process according to the principles of the present disclosure;

[0018] Figure 4A and Figure 4B shows a time domain parameter or profile comparison between a stamping process with shims and a stamping process with some shims removed in accordance with the principles of the present disclosure; and

[0019] Figure 5 A comparison of time domain parameters or profiles of an accelerometer on a pillow frame over two different cycles is shown, in accordance with the principles of the present disclosure.

[0020] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION

[0021] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding parts and features.

[0022] refer to Figure 1 and Figure 2 , a single action press 10 for stamping metal parts is shown. The press 10 includes a crown 12 and a press bed 14 supported on a base 16. The press 10 includes a slide 18 that moves downwardly while carrying an upper portion 20. The upper portion 20 captures a workpiece 24, such as, for example, a metal sheet, between it and a lower portion 26 positioned on a pillow 28.

[0023] like Figure 1 As shown, the lower part 26 is firmly attached to the press bed 14, so there is almost no force applied when the upper part 20 engages the workpiece 24. After the workpiece 24 is firmly clamped between the upper part 20 and the lower part 26, the slide 18 is actuated and moves downward, carrying a portion of the die. The upper part contacts the workpiece 24, pulling it over the lower part 26 into another portion of the die. The force applied by this action is not very high, because the movement is simply the upper part 20 pulling the already fixed workpiece 24 into the lower part 26. A toggle drive system 46 consisting of a flywheel, gears and other elements identified as 42 is attached to the crown 12. A motor 52 is used to provide mechanical power to the toggle drive system 46. Thus, the upper part 20 and the lower part 26 form a press assembly with a single slide 18. The lower part includes a die 30 and a set of stops 34 positioned around the die 30. The die 30 includes a concave channel 32, and the upper part 20 includes a corresponding die with a convex bead. Thus, the mold 30 , the female bead and the stop 34 cooperate with corresponding elements of the upper part 20 .

[0024] The upper portion 20 is configured to cooperate with the lower portion 26 to form the workpiece 24 into a desired shape. The press 10 also includes a blank holder 68 supported by nitrogen springs 70, 72. In addition, the press 10 includes a hydraulic stretch buffer assembly 74 supported by a press base 76, which helps absorb some of the forces during operation of the press 10. When the press 10 is operated, the elements of the press 10 can each have an actual lifespan that is generally consistent with their expected lifespan. As a single-action press, the press 10 facilitates faster transfer and additional operations to the workpiece 24.

[0025] In operation, Figure 1 The press 10 is shown with an unformed workpiece 24, with the stretch slide 18 in a raised position. The nitrogen springs 70, 72 raise the blank holder 68 above the top of the lower portion 26 so that the unformed workpiece 24 is supported by the blank holder 68, which provides a convenient orientation for the finished workpiece. As the slide 18 moves downward to apply force to the workpiece 24, capturing the workpiece between the upper portion 20 and the blank holder 68, the velocity of the lower portion 26 moves from zero velocity to match the velocity of the upper portion 20, and then as all three components move downward on the nitrogen cylinders 70, 72, the workpiece 24 and the blank holder 68 move from zero velocity to match the velocity of the upper portion 20. When the workpiece is positioned between the lower portion 26 and the upper portion 20, the lower portion 26 and the upper portion 20 are configured to come together so that the protruding beads cooperate with the concave channels 32 to apply a blank holding force (BHF) to the workpiece 24 to clamp the workpiece 24. To provide vibration data that may be used, for example, to modify the operation of press 10 , the one or more vibration sensors may be in the form of accelerometer 19 positioned on lower portion 26 and one or more accelerometers 21 positioned on bolster 28 .

[0026] A system for monitoring the operation of a press 10 is provided. Figure 1 124. System 124 includes vibration sensors 126, 128, 130, each in communication with a control system 132. Control system 132 includes a processing unit 134 having an electronic controller and memory therein, and a PLC 136 connected to processing unit 134. Baseline vibration levels defining vibration boundaries beyond which the life expectancy of one or more of the components of press 10 is reduced can be empirically determined by observing press operation in relation to information measured by the sensors. Such as sensor 126 on upper portion 20.

[0027] The baseline vibration level may be established using a system such as system 124, or may be established independently. The baseline vibration level information may be stored in the processing unit 134, for example, in the form of a lookup table. The PLC 136 provides additional information to the processing unit 134 related to the specific operation of the press 10. Such as the position of elements of the drive system 46 and the position of the stretch slide 18. The processing unit 134 also receives vibration data from the sensors 128, 130 and may correlate this information with the information measured from the sensor 126 on the upper portion 20.

[0028] The processing unit 134 may use one or more pre-programmed algorithms to establish a relationship between the vibration data measured by the sensor 126 and other vibration data input from other sensors, such as sensors 128, 130. Even after the sensor 126 is removed from the upper portion 20, the processing unit 134 may continue to receive information from the sensors 128, 130 and compare the information to the previously determined baseline vibration level. If at any time, the vibration measured by the sensors 128, 130 exceeds the baseline vibration level, the processing unit 134 may send an appropriate fault signal to alert the operator or production manager that adjustments need to be made. For example, it may be desirable to adjust some operating parameters of the press to help ensure that the vibration level remains below the baseline vibration level, or considering that certain press components may need to be replaced before they reach their expected life, it may be determined that it is acceptable to keep these vibration levels above the baseline vibration level.

[0029] In order to capture peak vibrations, it is desirable to have a very high data acquisition rate to retrieve vibration information from the sensors 126, 128, 130. For example, the raw signals from the sensors 126, 128, 130 may be sampled at a rate greater than 50,000 samples per second, thereby enabling the capture of signals with a maximum frequency of up to 10 kilohertz (KHz). One way to establish a baseline vibration level is to measure vibrations over a long period of time during many different operations, collect the vibration history and correlate it with the mechanical characteristics of the press elements. In this way, the relationship between vibrations at the press 10 and the shortened life of the press components may be determined.

[0030] The accelerometers 19 and 21 also communicate with the processing unit 134. The accelerometers 19 and 21 measure the time domain parameters or profiles or frequency domain parameters or profiles of the workpiece 24 flowing through the clamping point, and identify deviations from the ideal profile of each specific part being formed. As described above, there are multiple locations for accelerometer installation in the stamping die and press, including but not limited to on the mold (mold or die) near the metal forming, on the mold base (housing) of the lower part 26, and on the pillow frame 28 to which the lower part 26 is mounted. The time domain parameters or profiles or frequency domain parameters or profiles can be a function of the speed and / or other process parameters of the stamping machine operation, and a baseline is established by the stamping machine parameters. In addition, the time domain parameters or profiles or frequency domain parameters or profiles can be input into an artificial intelligence model, which can be trained to identify specific problems that cause specific changes in the input and notify the operating team before defects occur.

[0031] Steering Figure 3 , shows various stages of the stamping process measured by the accelerometer 19. Specifically, Figure 3The relationship between vibration amplitude and time measured by one or more accelerometers is shown. In a first stage, a workpiece 24, such as a metal plate, is placed in the press 10. Next, the position of the workpiece 24 is adjusted with an actuator. In a third stage, the upper part or die 20 contacts the workpiece 24. In a fourth stage, the accelerometer measures possible metal flow. In a fifth stage, the accelerometer 19 indicates that the press 10 has bottomed out, and in a sixth stage, the accelerometer 19 identifies metal flow. Finally, in a seventh stage, the accelerometer identifies when the upper part or die 20 separates from the workpiece 24. Therefore, the accelerometer 19 is able to identify metal flow and when the upper part 20 and the lower part 26 come together and separate. If the time domain parameter or profile or frequency domain parameter or profile measured by the accelerometer exceeds an upper limit, the BHF is too tight, and if the time domain parameter or profile or frequency domain parameter or profile is below a lower limit, the BHF is too loose. For example, if Figure 4A and Figure 4B As shown, the use of accelerometers 19 and / or 21 identifies the appropriate number of shims to be placed under stop block 34. Specifically, Figure 4A Indicates the appropriate number of shims, while Figure 4B Indicates insufficient number of shims.

[0032] Reference now Figure 5 , shows vibration signatures measured over two different press cycles with one or more of the accelerometers 21 positioned on the pillow frame 28. A lighter mark shifted to the left indicates that the upper portion 20 is misaligned with the lower portion 26, while a darker mark shifted to the right indicates that the upper portion 20 is properly aligned with the lower portion 26. In various arrangements of the press 10, when the vibration signature of the accelerometer 19 matches the vibration signature of the accelerometer 21, then the lower portion 26 is not provided with an accelerometer because the accelerometer 21 on the pillow frame 28 provides sufficient feedback to the operation of the press 10.

[0033] Among other benefits and advantages, the press 10 predictively identifies process variations, enhances quality control, and reduces waste. In addition, the press 10 reduces the number of personnel required to triage quality issues and reduces the number of locations to investigate issues.

[0034] Unless otherwise expressly indicated herein, all numerical values ​​indicating mechanical / thermal properties, composition percentages, dimensions and / or tolerances or other characteristics when describing the scope of the present disclosure should be understood to be modified by the word "about" or "approximately". Such modifications are desirable for a variety of reasons, including: industrial practice; material, manufacturing and assembly tolerances; and testing capabilities.

[0035] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical "or", and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0036] In this application, the terms "controller" and / or "module" may refer to, be part of, or include: an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinatorial logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality (e.g., an operational amplifier circuit integrator as part of a heat flux data module); or a combination of some or all of the above, such as in a system on a chip.

[0037] The term memory is a subset of the term computer-readable medium. The term computer-readable medium as used herein does not encompass transient electrical or electromagnetic signals propagated through a medium (such as on a carrier wave); therefore, the term computer-readable medium may be considered to be tangible and non-transitory. Non-limiting examples of non-transitory tangible computer-readable media are non-volatile memory circuits (such as flash memory circuits, erasable programmable read-only memory circuits, or mask read-only circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital tape or hard drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0038] The apparatus and methods described in this application may be implemented partially or completely by a special-purpose computer, which is created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. The functional blocks, flow chart components, and other elements described above are used as software specifications, which can be translated into a computer program by routine work of a technician or programmer.

[0039] The description of the present disclosure is merely exemplary in nature, and thus, variations that do not depart from the essence of the present disclosure are intended to be within the scope of the present disclosure. Such variations should not be regarded as a departure from the spirit and scope of the present disclosure.

[0040] According to the present invention, a die for stamping a metal sheet is provided, comprising: a first portion having a convex bead; a second portion having a concave channel; a pillow frame to which the second portion is fixed; and at least one accelerometer positioned on the pillow frame, wherein when a metal sheet is positioned between the first portion and the second portion, the first portion and the second portion are configured to be brought together so that the convex bead cooperates with the concave channel to apply a blank holding force (BHF) to the metal sheet to clamp the metal sheet, and wherein the at least one accelerometer measures a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal sheet.

[0041] According to an embodiment, the invention is also characterized by at least one other accelerometer positioned near the concave channel to measure a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal plate between the first portion and the second portion.

[0042] According to an embodiment, the first portion comprises a preformed convex shape and the second portion comprises a preformed concave shape.

[0043] According to an embodiment, when the first part and the second part are brought together to clamp the metal sheet, a part having a shape defined by the preformed concave shape and the preformed convex shape is produced.

[0044] According to an embodiment, the at least one accelerometer comprises a plurality of accelerometers positioned on the pillow frame.

[0045] According to an embodiment, if the time domain parameter or profile or the frequency domain parameter or profile exceeds an upper limit, the BHF is excessive.

[0046] According to an embodiment, if the time domain parameter or profile or the frequency domain parameter or profile is below a lower limit, the BHF is insufficient.

[0047] According to the present invention, a system for stamping a metal sheet is provided, comprising: a first part, the first part having a convex bead; a second part, the second part having a concave channel; a pillow frame, the second part being fixed to the pillow frame; a plurality of accelerometers, the plurality of accelerometers being positioned at least on the second part and the pillow frame; and a processing unit, the processing unit communicating with the plurality of accelerometers, wherein when a metal sheet is positioned between the first part and the second part, the first part and the second part are configured to be brought together so that the convex bead cooperates with the concave channel to apply a blank holding force (BHF) to the metal sheet to clamp the metal sheet, and wherein the plurality of accelerometers measure time domain parameters or profiles or frequency domain parameters or profiles during placement of the metal sheet, and the time domain parameters or profiles or the frequency domain parameters or profiles are transmitted to the processing unit.

[0048] According to an embodiment, the first part comprises a preformed convex shape and the second part comprises a preformed concave shape, and wherein when the first part and the second part are brought together to clamp the metal sheet, a part having a shape defined by the preformed concave shape and the preformed convex shape is produced.

[0049] According to an embodiment, if the time domain parameter or profile or the frequency domain parameter or profile exceeds an upper limit, the BHF is excessive.

[0050] According to an embodiment, if the time domain parameter or profile or the frequency domain parameter or profile is below a lower limit, the BHF is insufficient.

Claims

1. A die for stamping a metal plate, the die comprising: a first portion, the first portion having a convex bead; a second portion, the second portion having a concave channel; as well as at least one accelerometer, the at least one accelerometer positioned proximate the concave channel, Wherein when the metal plate is positioned between the first part and the second part, the first part and the second part are configured to be brought together so that the convex bead cooperates with the concave channel to apply a blank holding force (BHF) to the metal plate to clamp the metal plate, and wherein the at least one accelerometer measures a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal plate.

2. The mold of claim 1, wherein the first portion comprises a preformed convex shape and the second portion comprises a preformed concave shape.

3. The mold of claim 2, wherein when the first portion and the second portion are brought together to clamp the metal sheet, a part having a shape defined by the preformed concave shape and the preformed convex shape is produced.

4. The mold of claim 1, wherein the at least one accelerometer comprises a plurality of accelerometers positioned around a perimeter of the concave channel.

5. The mold of claim 1, wherein if the time domain parameter or profile or the frequency domain parameter or profile exceeds an upper limit, the BHF is excessive.

6. The mold of claim 1, wherein if the time domain parameter or profile or the frequency domain parameter or profile is below a lower limit, the BHF is insufficient.

7. The mold of claim 1 further comprising a pillow frame, the second portion being secured to the pillow frame.

8. The mold of claim 7, further comprising at least one other accelerometer positioned on the pillow frame to measure a time domain parameter or profile or a frequency domain parameter or profile during placement of the metal plate between the first portion and the second portion.

9. The mold of claim 8, wherein the at least one other accelerometer comprises a second plurality of accelerometers.

10. The mold of claim 8, further comprising a processing unit in communication with the at least one accelerometer and the at least one other accelerometer.

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