Blank holder force detection method for a press

Abstract

The application provides a blank holder force detection method of a stamping device, and belongs to the technical field of stamping production. The blank holder force detection method comprises the following steps: stamping a test piece; obtaining a blank holder force P at a first blank holder ring; when the test piece is cracked and / or wrinkled after stamping, the blank holder force P is a defective blank holder force P 缺陷 ; recording the defective blank holder force P 缺陷 and establishing a defective blank holder force P 缺陷 threshold value, wherein the defective blank holder force P 缺陷 threshold value comprises a blank holder force too large threshold value and a blank holder force too small threshold value; detecting the blank holder force P at the first blank holder ring in a production process, comparing the blank holder force P with the defective blank holder force P 缺陷 threshold value, and issuing an alarm if the blank holder force P is greater than the blank holder force too large threshold value or smaller than the blank holder force too small threshold value.

Description

Technical Field

[0001] This invention relates to the field of stamping production technology, and in particular to a method for detecting the blank holder force of stamping equipment. Background Technology

[0002] During sheet metal stamping, the upper and lower pressure rings of the stamping equipment clamp the sheet metal in the middle to limit its feed speed. If the pressure is too high, the gap between the upper and lower pressure rings will be smaller than normal, reducing the feed speed during the stretching process and making it prone to cracking. If the pressure is too low, the gap between the upper and lower dies will be larger than normal, causing the feed speed during the stretching process to be too fast, which will make it prone to wrinkling.

[0003] Before stamping equipment leaves the factory, manufacturers need to measure and adjust the blank holder force of the stamping equipment's testing platform to establish standard parameters. Under these standard parameters, qualified products that will not crack and / or wrinkle can be produced. After the finished stamping equipment leaves the factory, due to machine differences and variations, the blank holder force of the stamping equipment needs to be measured and adjusted again based on the factory parameters before it can be put into stamping production.

[0004] Existing methods for measuring blank holder force involve applying styrofoam to the balance block of the blank holder ring. After one stamping cycle, the depth of the styrofoam color pressed onto the balance block is used to determine the size of the gap between the upper and lower blank holder rings. However, this manual application of styrofoam cannot quantify the pressure value, relying entirely on subjective and experience-based judgment. This leads to inaccurate assessments and significant discrepancies between the adjusted parameters and the factory specifications. Consequently, stamped products may exhibit cracking and / or wrinkling. Furthermore, the pressure cannot be monitored in real-time during the stamping process, failing to provide parameters for production quality control. Summary of the Invention

[0005] The purpose of this invention is to provide a method for detecting the blank holder force of a stamping equipment. This method solves the problem that the blank holder force cannot be accurately quantified because it is impossible to judge the size of the gap between the upper and lower blank holder rings by manually observing the color of the blue lead oil pressed into the balance block. It enables real-time monitoring of the pressure during production after mass production, provides accurate thresholds for monitoring production quality, quantifies the pressure value of key areas, and serves as a reference for the stamping equipment to be debugged on the production line.

[0006] To achieve the objectives of this invention, the following technical solution is adopted:

[0007] This invention provides a method for detecting the blank holder force of a stamping equipment. The stamping equipment includes at least one pressure sensor, a first die, a second die, a first blank holder ring, a second blank holder ring, and a blank holder cylinder. The first die and the second die are arranged opposite to each other and configured to cooperate in forming a sheet metal part. The first blank holder ring is movably disposed on the first die and surrounds the first die. The second blank holder ring is disposed on the second die corresponding to the first blank holder ring. The blank holder cylinder is connected to the first blank holder ring. The pressure sensor is disposed between the first blank holder ring and the second blank holder ring and is configured to measure the blank holder force applied by the first blank holder ring. The blank holder force detection method includes:

[0008] The test piece is stamped;

[0009] Obtain the blank holder force P at the first blank holder ring;

[0010] When the stamped test piece has cracks and / or wrinkles, the blank holder force P is the defect blank holder force P. 缺陷 ;

[0011] Record the blank holder force P for defects 缺陷 And establish the defect blank holder force P 缺陷 Threshold, blank holder force P 缺陷 The thresholds include the threshold for excessive blank holder force and the threshold for insufficient blank holder force;

[0012] During the production process, the blank holder force P at the first blank holder ring is detected, and the blank holder force P and the defective blank holder force P are compared. 缺陷 A threshold is compared, and if the blank holder force P is greater than the excessive blank holder force threshold or less than the insufficient blank holder force threshold, an alarm is issued.

[0013] According to one embodiment of the present invention, obtaining the blanking force generated at the first blanking ring includes: a plurality of pressure sensors are spaced apart on the first blanking ring, and when the first blanking ring and the second blanking ring jointly clamp the edge of the test piece, the pressure sensors abut against the second blanking ring to obtain the blanking force P.

[0014] According to one embodiment of the present invention, obtaining the blank holder force P generated at the first blank holder ring further includes: stamping out multiple test pieces, and measuring the blank holder force P in real time during the stamping of each test piece. 实 Real-time recording of blank holder force P 实 .

[0015] According to one embodiment of the present invention, when the stamped test piece has cracks and / or wrinkles, the blank holder force P is the defect blank holder force P. 缺陷 This includes: removing each test piece after stamping and observing for defects; if defects are found, adjusting the blank holder force P corresponding to the defective test piece. 实 The blank holder force P is determined to be a defect. 缺陷 .

[0016] According to one embodiment of the present invention, before stamping the test piece, the method further includes: controlling the output pressure of the edge-pressing cylinder so that the output pressure of the edge-pressing cylinder is different for each test piece before stamping.

[0017] According to one embodiment of the present invention, a plurality of balance blocks for abutting against a second pressure ring are provided on the first pressure ring, and before stamping the test piece, the balance blocks are provided with a different number of shims.

[0018] According to one embodiment of the present invention, the second pressure ring is provided with a top block corresponding to the pressure sensor, and the abutting surface of the top block matches the sensing surface of the pressure sensor. When the second pressure ring and the first pressure ring clamp the test piece together, the sensing surface of the pressure sensor abuts against the abutting surface of the top block.

[0019] According to one embodiment of the present invention, the method further includes obtaining a parameter for the parallelism of the first and second pressure rings, comparing the parallelism parameter with a preset standard parallelism threshold, and determining that the first and second pressure rings are not parallel if the parallelism parameter exceeds the standard parallelism threshold; and determining that the first and second pressure rings are parallel if the obtained parallelism parameter is within the standard parallelism threshold.

[0020] According to one embodiment of the present invention, the parameters for obtaining the parallelism of the first and second pressure rings include: obtaining the pressure difference P between the pressure sensors of the two rings. 差 .

[0021] According to an embodiment of the present invention, after the stamping equipment is shipped from the factory to the production line and before it is put into production, the stamping equipment is debugged, and the debugging includes:

[0022] The test piece is stamped;

[0023] When there are multiple pressure sensors, if the blanking force measured by at least one of the pressure sensors is greater than the excessive blanking force threshold, the number of pads on the balance block adjacent to that pressure sensor will be increased accordingly.

[0024] If the blank holder force measured by at least one of the pressure sensors is less than the minimum blank holder force threshold, the number of shims on the balance block adjacent to that pressure sensor shall be reduced or the shims shall be removed accordingly.

[0025] If the blank holder force measured by all pressure sensors is greater than the excessive blank holder force threshold, then the output pressure of the blank holder cylinder should be reduced accordingly.

[0026] If the blank holder force measured by all pressure sensors is less than the minimum blank holder force threshold, then the output pressure of the blank holder cylinder should be increased accordingly.

[0027] Until the blank holder force measured by all pressure sensors is less than the excessive blank holder force threshold and greater than the insufficient blank holder force threshold.

[0028] One embodiment of the present invention has the following advantages or beneficial effects:

[0029] The present invention discloses a method for detecting the blank holder force of a stamping equipment. The stamping equipment includes at least one pressure sensor, a first die, a second die, a first blank holder ring, a second blank holder ring, and a blank holder cylinder. The first die and the second die are arranged opposite to each other and configured to cooperate in forming a sheet metal part. The first blank holder ring is movably disposed on the first die and surrounds the first die. The second blank holder ring is disposed on the second die corresponding to the first blank holder ring. The blank holder cylinder is connected to the first blank holder ring. The pressure sensor is disposed between the first blank holder ring and the second blank holder ring and is configured to measure the blank holder force applied by the first blank holder ring. The blank holder force detection method includes:

[0030] The test piece is stamped;

[0031] Obtain the blank holder force P at the first blank holder ring;

[0032] When the stamped test piece has cracks and / or wrinkles, the blank holder force P is the defect blank holder force P. 缺陷 ;

[0033] Record the blank holder force P for defects 缺陷 And establish the defect blank holder force P 缺陷 Threshold;

[0034] During the production process, the blank holder force P at the first blank holder ring is detected, and the blank holder force P and the defective blank holder force P are compared. 缺陷 Threshold comparison: If the blank holder force P is located at the defect blank holder force P 缺陷 When the threshold is reached, an alarm will be issued.

[0035] Because the pressure values ​​measured by pressure sensors are positively correlated with defects such as wrinkling and cracking, stamping die equipment can monitor the pressure during production in real time after mass production. This provides thresholds for monitoring production quality, allowing the stamping die equipment to have quantified pressure values ​​for key areas, serving as a reference for the equipment's return to the production line for debugging. For example, after the stamping die equipment is manufactured and debugged by the die manufacturer, its pressure sensor information is recorded as standard parameters. When the stamping die equipment returns to the production line, due to machine differences and variations, cracking and wrinkling may occur during debugging. By comparing the pressure values ​​measured during production line debugging with the standard parameters of the pressure sensors before shipment, the stamping equipment can be debugged. During debugging, if the blank holder force measured by all sensors is greater than the excessive blank holder force threshold or less than the insufficient blank holder force threshold, the output pressure of the blank holder cylinder is correspondingly reduced or increased until all pressure sensors measure the required pressure. The blank holder force is less than the excessive blank holder force threshold and greater than the insufficient blank holder force threshold. If the blank holder force measured by at least one of the pressure sensors is greater than the excessive blank holder force threshold or less than the insufficient blank holder force threshold, the number of shims on the balance block adjacent to the pressure sensor is increased or decreased accordingly until the blank holder force measured by the pressure sensor is less than the excessive blank holder force threshold and greater than the insufficient blank holder force threshold. This eliminates the need to stop the machine and manually apply blue lead oil, improving the accuracy of judgment and the efficiency of measurement and debugging. It enables real-time monitoring of the blank holder force during the stamping process, thereby providing parameters for production quality monitoring. Attached Figure Description

[0036] The above and other features and advantages of the present invention will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0037] Figure 1 This is a cross-sectional view of a stamping device according to an exemplary embodiment.

[0038] Figure 2 This is another cross-sectional view of a stamping device according to an exemplary embodiment.

[0039] Figure 3 This is a schematic diagram of the distribution of pressure sensors in a stamping device during the stamping of a side panel, according to an exemplary embodiment.

[0040] Figure 4 This is a schematic diagram of the distribution of pressure sensors when a stamping device is stamping an inner panel of a door, according to an exemplary embodiment.

[0041] The reference numerals in the attached figures are explained as follows:

[0042] 1. Pressure sensor; 11. Mounting base; 2. First mold; 3. Second mold; 4. First pressure ring; 41. Balance block; 5. Second pressure ring; 51. Top block; 6. Test piece. Detailed Implementation

[0043] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0044] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended meaning of inclusion and that other elements / components / etc. may exist in addition to the listed elements / components / etc.

[0045] like Figure 1-4 As shown in the figure, an embodiment of the present invention provides a method for detecting the blank holder force of a stamping equipment, wherein the stamping equipment includes at least one pressure sensor 1, a first mold 2, a second mold 3, a first blank holder ring 4, a second blank holder ring 5, and a blank holder cylinder.

[0046] The first mold 2 and the second mold 3 are arranged opposite each other and configured to work together to form the sheet metal. For example, the second mold 3 is located directly above the first mold 2. During stamping, the second mold 3 moves downward perpendicular to the horizontal plane and works with the first mold 2 to stamp and form the sheet metal.

[0047] The first pressing ring 4 is movably disposed on the first mold 2 and surrounds the first mold 2. The inner edge of the first pressing ring 4 has a clamping part. The second pressing ring 5 is disposed on the second mold 3 corresponding to the first pressing ring 4.

[0048] The pressing cylinder is connected to the first pressing ring 4 via a push rod on the worktable and drives the first pressing ring 4 to move up and down. The force of the pressing cylinder is controlled by increasing or decreasing air pressure, for example, by inputting a value in MPa through the controller parameter input module.

[0049] Pressure sensor 1 is disposed between the first pressing ring 4 and the second pressing ring 5, and close to the outer edge of the first pressing ring 4 and the second pressing ring 5. Pressure sensor 1 is configured to measure the pressing force applied by the first pressing ring 4.

[0050] After the plate is placed on the first mold 2, the second mold 3 moves downward and applies pressure to the plate towards the first mold 2. At the same time, the edge-pressing cylinder drives the first edge-pressing ring 4 upward and together with the second edge-pressing ring 5 to clamp the edge of the plate to limit the plate feeding speed. At this time, the two ends of the pressure sensor 1 abut against the first edge-pressing ring 4 and the second edge-pressing ring 5 respectively to obtain the edge-pressing force at the first edge-pressing ring 4.

[0051] The blank holder force detection method includes:

[0052] Test piece 6 is stamped;

[0053] Obtain the blank holder force P at point 4 of the first blank holder ring;

[0054] When the stamped test piece 6 has cracks and / or wrinkles, the blank holder force P is the defect blank holder force P. 缺陷 And the defect blank holder force P 缺陷 Set as alarm parameter; when test piece 6 does not show cracks or wrinkles, the blank holder force P is the qualified blank holder force P. 合格 ;

[0055] The defect clamping force P 缺陷 Set as an alarm parameter, and set the qualified blank holder force P 合格 Set as standard parameters;

[0056] Record the blank holder force P for defects 缺陷 And establish the defect blank holder force P 缺陷 Threshold;

[0057] During the production process, the blank holder force P at point 4 of the first blank holder ring is detected, and the blank holder force P and the defective blank holder force P are compared. 缺陷 Threshold comparison: If the blank holder force P is located at the defect blank holder force P 缺陷 If the threshold is met, an alarm will be triggered.

[0058] The blank holder force detection method of this invention, because the obtained blank holder force is positively correlated with defects such as wrinkling and cracking, allows for real-time monitoring of the blank holder force during production after the stamping equipment is in mass production. This provides a threshold for monitoring production quality, enabling the stamping equipment to have quantified pressure values ​​in key areas, serving as a reference for the stamping equipment's return to the production line for debugging. It eliminates the need for machine shutdown and manual application of blue lead oil, improving the accuracy of judgment and the efficiency of measurement and debugging. It achieves real-time monitoring of the blank holder force during the forming process of stamped parts, thereby providing parameters for production quality monitoring.

[0059] In a preferred embodiment of the present invention, obtaining the pressing force generated at the first pressing ring 4 includes: multiple pressure sensors 1 are spaced apart and mounted on the first pressing ring 4; and when the first pressing ring 4 and the second pressing ring 5 jointly clamp the edge of the test piece 6, the pressure sensors 1 abut against the second pressing ring 5 to obtain the pressing force P. The use of multiple pressure sensors 1 further improves the acquisition accuracy.

[0060] Optionally, each pressure sensor 1 can be positioned near areas of the test piece prone to cracking and / or wrinkling to further improve measurement accuracy. For example, such as Figure 3 , 4As shown, during the stamping process, the inner door panel and side panel of the vehicle are prone to cracking and / or wrinkling defects in areas A, B, C, and D. Multiple pressure sensors 1 are arranged close to areas A, B, C, and D respectively.

[0061] In a preferred embodiment of the present invention, obtaining the blanking force P generated at the first blanking ring 4 further includes: stamping out multiple test pieces 6, and measuring the blanking force P in real time when stamping each test piece 6. 实 Real-time recording of blank holder force P 实。 The multiple test pieces 6 include multiple defective test pieces and multiple qualified test pieces. For example, the multiple defective test pieces may include at least one test piece with wrinkling defects, at least one test piece with cracking defects, and at least one test piece with both cracking and wrinkling defects. This embodiment, by using multiple test pieces, achieves richer data information and reduces risks in later production processes.

[0062] Among them, the minimum value of the multiple clamping forces recorded for multiple cracked test pieces is the threshold for excessive clamping force, and the maximum value of the multiple clamping forces recorded for multiple wrinkled test pieces is the threshold for insufficient clamping force.

[0063] In a preferred embodiment of the present invention, when the stamped test piece 6 has cracks and / or wrinkles, the blank holder force P is the defect blank holder force P. 缺陷 This includes: removing each test piece 6 after stamping and observing for defects. If a defect is found, the blank holder force P corresponding to the defective test piece 6 is adjusted. 实 The blank holder force P is determined to be a defect. 缺陷 And the blank holder force P of the defect will be applied. 缺陷 Input relevant alarm information items, such as cracking alarm items, wrinkling alarm items, and cracking and wrinkling items, to establish defect edge clamping force thresholds and data information on various defects.

[0064] If there are no defects, then the blank holder force P corresponding to the defect-free test piece 6 will be applied. 实 The blank holder force P is deemed acceptable. 合格 And the qualified blank holder force P 合格 Enter this into the standard information item to establish the standard blank holder force threshold.

[0065] In a preferred embodiment of the present invention, before stamping the test piece 6, the method further includes controlling the output pressure of the edge-pressing cylinder so that the output pressure of the edge-pressing cylinder is different for each test piece 6 before stamping. This allows for the acquisition of test pieces with various defects or qualified test pieces under different edge-pressing cylinder output pressures, enriching the detection threshold. For example, when the output pressure of the edge-pressing cylinder is too high, a test piece with severe overall cracking can be obtained. When the output pressure of the edge-pressing cylinder is too low, a test piece with severe overall wrinkling can be obtained.

[0066] like Figure 4 As shown, in a preferred embodiment of the present invention, the first pressure ring 4 is provided with a plurality of balance blocks 41 for abutting against the second pressure ring 5. Before stamping the test piece 6, the method further includes: each balance block 41 is provided with a different number of shims. For example, adding or removing shims on certain balance blocks 41 can adjust whether the test piece has local wrinkles, local cracks, or no cracks and no wrinkles.

[0067] like Figure 1 , 2 As shown, in a preferred embodiment of the present invention, the second pressure ring 5 is provided with a top block 51 corresponding to the pressure sensor 1, and the abutting surface of the top block 51 matches the sensing surface of the pressure sensor 1. When the second pressure ring 5 and the first pressure ring 4 jointly clamp the test piece 6, the sensing surface of the pressure sensor 1 abuts against the abutting surface of the top block 51, thereby improving the service life of the pressure sensor 1 and avoiding damage to the sensing surface due to mismatch. For example, when the sensing surface of the pressure sensor 1 is spherical, the abutting surface of the top block 51 is correspondingly an arc-shaped groove. In addition, the concave and convex pressure also achieves automatic alignment and avoids misalignment.

[0068] When the sensing surface of pressure sensor 1 comes into contact with the contact surface of top block 51, pressure sensor 1 generates different electrical signals according to different contact pressures.

[0069] In a preferred embodiment of the present invention, the method further includes obtaining parameters of the parallelism between the first pressure ring 4 and the second pressure ring 5, comparing the parallelism parameters with a preset standard parallelism threshold, and determining that the first pressure ring 4 and the second pressure ring 5 are not parallel if the parallelism parameters exceed the standard parallelism threshold, triggering an alarm or maintenance prompt; if the obtained parallelism parameters are within the standard parallelism threshold, determining that the first pressure ring 4 and the second pressure ring 5 are parallel, thereby realizing the monitoring of the balance of the contact force when the parts of the first pressure ring 4 and the second pressure ring 5 abut together. When the contact force of the parts of the first pressure ring 4 and the second pressure ring 5 is uneven, cracking and / or wrinkling defects are likely to occur.

[0070] In a preferred embodiment of the present invention, obtaining the parameter for the parallelism of the first pressure ring 4 and the second pressure ring 5 includes: obtaining the pressure difference P between the pressure sensors 1 between them. 差 For example, a first detection group and a second detection group are arranged on both sides of the first pressure ring 4. Each of the first and second detection groups includes two pressure sensors 1 to obtain the difference between the sum of the pressure values ​​of the first detection group and the sum of the pressure values ​​of the second detection group.

[0071] Of course, the first and second detection groups are not limited to including two pressure sensors 1. Those skilled in the art can select the number of pressure sensors 1 according to actual needs.

[0072] In one embodiment of the present invention, after the stamping equipment is shipped from the factory to the production line and before it is put into production, the stamping equipment is debugged. The debugging of the stamping equipment includes:

[0073] Test piece 6 is stamped;

[0074] When there are multiple pressure sensors 1, for example, when there are eight pressure sensors 1, the multiple pressure sensors 1 are numbered. If the blank-pressing force measured by the pressure sensor numbered first and / or second is greater than the excessive blank-pressing force threshold, the number of shims on the balance block 41 adjacent to the first and / or second pressure sensor 1 is increased accordingly to reduce the blank-pressing force at the first and / or second pressure sensor 1, until the blank-pressing force measured by all pressure sensors 1 is less than the excessive blank-pressing force threshold and greater than the insufficient blank-pressing force threshold, that is, until the blank-pressing force measured by all pressure sensors 1 is the qualified blank-pressing force P. 合格 During this time, adjustments are completed to address localized cracking or wrinkling of the stamped parts.

[0075] If the blanking force measured by pressure sensor 1 (number 1) is less than the minimum blanking force threshold, the number of shims on the balance block 41 adjacent to pressure sensor 1 is reduced or the shims are removed to increase the blanking force at pressure sensor 1. This process continues until the blanking forces measured by all pressure sensors 1 are less than the maximum blanking force threshold and greater than the minimum blanking force threshold, thus completing the debugging.

[0076] If the blank holder force measured by all pressure sensors 1 is greater than the excessive blank holder force threshold, then the output pressure of the blank holder cylinder is reduced accordingly until the blank holder force measured by all pressure sensors 1 is less than the excessive blank holder force threshold and greater than the insufficient blank holder force threshold, thus completing the debugging.

[0077] If the blanking force measured by all pressure sensors 1 is less than the blanking force threshold, the output pressure of the blanking cylinder is increased accordingly until the blanking force measured by all pressure sensors 1 is less than the blanking force threshold and greater than the blanking force threshold, thus completing the debugging.

[0078] In this embodiment of the invention, the term "multiple" refers to two or more, unless otherwise explicitly defined. The terms "install," "connect," and "fix" should be interpreted broadly. For example, "connect" can mean a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention based on the specific circumstances.

[0079] In the description of the embodiments of the present invention, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0080] In the description of this specification, the terms "an embodiment," "a preferred embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. For those skilled in the art, the embodiments of the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of the present invention should be included within the protection scope of the embodiments of the present invention.

Claims

1. A method for detecting the blank holder force of a stamping equipment, characterized in that, The stamping equipment includes multiple pressure sensors, a first die, a second die, a first blank holder ring, a second blank holder ring, and a blank holder cylinder. The first die and the second die are arranged opposite to each other and configured to cooperate in forming a sheet metal part. The first blank holder ring is movably disposed on the first die and surrounds the first die. The second blank holder ring is disposed on the second die corresponding to the first blank holder ring. The blank holder cylinder is connected to the first blank holder ring. The pressure sensors are disposed between the first blank holder ring and the second blank holder ring and are configured to measure the blank holder force applied by the first blank holder ring. The first blank holder ring is provided with multiple balance blocks for abutting against the second blank holder ring, and each balance block is provided with a different number of shims. The blank holder force detection method includes: The test piece is stamped; Obtain the blank holder force P at the first blank holder ring; When the stamped test piece exhibits cracking and / or wrinkling, the blank holder force P is the defect blank holder force P. 缺陷 ; Record the blank holder force P for defects 缺陷 And establish the defect blank holder force P 缺陷 Threshold, the defect clamping force P 缺陷 The thresholds include the threshold for excessive blank holder force and the threshold for insufficient blank holder force; During the production process, the blank holder force P at the first blank holder ring is detected, and the blank holder force P and the defective blank holder force P are compared. 缺陷 A threshold comparison is performed. If the blank holder force P is greater than the excessive blank holder force threshold or less than the insufficient blank holder force threshold, an alarm is issued. If the blanking force measured by at least one of the pressure sensors is greater than the excessive blanking force threshold, the number of shims on the balance block adjacent to the pressure sensor is increased accordingly; if it is less than the insufficient blanking force threshold, the number of shims on the balance block adjacent to the pressure sensor is reduced or the shims are removed accordingly. If the blanking force measured by all pressure sensors is greater than the excessive blanking force threshold, the output pressure of the blanking cylinder will be reduced accordingly; if the blanking force is less than the insufficient blanking force threshold, the output pressure of the blanking cylinder will be increased accordingly. Until all pressure sensors measure a blank holder force that is less than the excessive blank holder force threshold and greater than the insufficient blank holder force threshold.

2. The method for detecting blank holder force according to claim 1, characterized in that, The step of obtaining the blanking force generated at the first blanking ring includes: multiple pressure sensors are installed at intervals on the first blanking ring, and when the first blanking ring and the second blanking ring jointly clamp the edge of the test piece, the pressure sensors abut against the second blanking ring to obtain the blanking force P.

3. The method for detecting blank holder force according to claim 2, characterized in that, The step of obtaining the blank holder force P generated at the first blank holder ring further includes: stamping out multiple test pieces, and measuring the blank holder force P in real time when stamping each test piece. 实 The blank holder force P is recorded in real time. 实。 4. The method for detecting blank holder force according to claim 1, characterized in that, When the stamped test piece exhibits cracking and / or wrinkling, the blank holder force P is the defect blank holder force P. 缺陷 This includes: removing each test piece after stamping and observing for defects; if defects are found, adjusting the blank holder force P corresponding to the defective test piece. 实 The blank holder force P is determined to be a defect. 缺陷 .

5. The method for detecting blank holder force according to claim 1, characterized in that, Before stamping the test piece, the method further includes controlling the output pressure of the edge-pressing cylinder so that the output pressure of the edge-pressing cylinder is different for each test piece before stamping.

6. The method for detecting blank holder force according to claim 1, characterized in that, The second pressure ring is provided with a top block corresponding to the pressure sensor, and the abutting surface of the top block matches the sensing surface of the pressure sensor. When the second pressure ring and the first pressure ring clamp the test piece together, the sensing surface of the pressure sensor abuts against the abutting surface of the top block.

7. The method for detecting blank holder force according to claim 1, characterized in that, It also includes obtaining parameters of the parallelism between the first and second pressure rings, comparing the parallelism parameters with a preset standard parallelism threshold, and determining that the first and second pressure rings are not parallel if the parallelism parameters exceed the standard parallelism threshold; and determining that the first and second pressure rings are parallel if the obtained parallelism parameters are within the standard parallelism threshold.

8. The method for detecting blank holder force according to claim 7, characterized in that, The parameters for obtaining the parallelism of the first and second pressure rings include: obtaining the pressure difference P between the pressure sensors of the two rings. 差 .

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