A method and system for adaptive feedback adjustment of a draw bead line of a stamping die

Abstract

This invention provides an adaptive feedback adjustment method and system for the drawing take-up line of a stamping die. The method includes triggering a grating projection device to project a grating grid onto the drawing die, controlling an industrial camera to capture an image of the lower drawing die, receiving the image of the lower drawing die captured by the industrial camera, identifying edge feature points of the drawing line in the lower drawing die image, and fitting a drawing take-up line profile based on the identified edge feature points. The fitted drawing take-up line profile is then compared with a pre-stored standard drawing take-up line to determine if the profile contains any out-of-limit areas. This invention employs a unique online measurement method, enabling adjustment of the stamping die's drawing take-up line without stopping the machine. This system is applicable to all dies and saves significant process and production costs compared to existing measurement methods that require offline shutdown.

Description

Technical Field

[0001] This invention relates to automatic control methods and equipment for stamping dies, and more specifically to an adaptive feedback adjustment method and system for a stamping die drawing take-up line. Background Technology

[0002] In the stamping industry, the forming process of stamped parts is affected by changes in the surrounding environment (including but not limited to: temperature, sheet metal properties, lubricating oil film, mold / equipment condition, etc.), causing changes in the take-up line of the stamping die, which in turn leads to quality problems such as tearing, necking, wrinkling, and dimensional changes in the finished stamped parts. The change in the take-up line of the stamping die is a subtle, gradual process, accompanied by noise and vibration from stamping production. For a long time, online non-contact measurement or monitoring has been impossible, remaining a bottleneck problem in the industry that urgently needs to be overcome.

[0003] Currently, the only commonly used offline contact measurement method is the offline comparison method for drawn parts. This method requires intermittent machine stops, where drawn parts produced by stamping dies at different times are removed from the press production line. Multiple drawn parts are stacked together, and the change value is obtained by measuring and comparing the edge contour of the receiving line with a ruler. This method generates a large number of process stops and poses safety hazards such as scratches. The second offline contact measurement method is the die blanking ring engraving method. This method requires pre-etching a standard scale line on the blanking ring of the drawing die. It also requires intermittent machine stops. After stopping, personnel enter the press and directly measure the distance between the standard scale line on the blanking ring and the actual edge contour of the receiving line on the die inside the press, thus indirectly obtaining the change value of the receiving line. This method generates a large number of process stops and poses safety hazards such as scratches. More importantly, the undulating shape of the blanking ring makes it difficult to guarantee the accuracy of the measurement value, often resulting in a large deviation (more than 1mm). The above measurement methods have the following defects: (1) They are all offline measurement methods, which require machine stoppage for measurement, resulting in a large number of process downtimes; (2) The measurement accuracy is poor, and the manual contact measurement generally has a deviation at the mm level; (3) Because machine stoppage is required, the measurement is intermittent (usually measured once every 200-300 pieces), and continuous production status data cannot be obtained; (4) There are safety hazards such as scratches.

[0004] Some companies or organizations use ATOS optical dimension scanning equipment for offline scanning and measurement to improve the measurement accuracy of the receiving line contour, but the disadvantages of offline measurement still exist. Furthermore, ATOS optical dimension scanning equipment cannot perform measurements under high-speed vibration.

[0005] Invention Patent Content

[0006] To address the aforementioned problems, this invention provides an adaptive feedback adjustment method and system for the drawing take-up line of a stamping die. This method, through real-time online, non-contact operation, enables high-precision online continuous detection while simultaneously processing the detection signals and feeding them back to the servo press system. This drives the servo press to adaptively adjust the stamping force, forming a control closed loop that keeps the drawing take-up line of the stamping die consistently stable within a defined range. The objective of this invention is achieved through the following technical solutions:

[0007] This invention first provides an adaptive feedback adjustment method for the drawing take-up line of a stamping die, which includes the following steps:

[0008] Step S10: Trigger the grating projection device to project the grating grid onto the drawing die;

[0009] Step S20: Control the industrial camera to take a picture of the drawing die of the stamping die with a grating grid background;

[0010] Step S30: Receive the drawing die photo taken by the industrial camera, identify the edge feature points of the drawing line in the drawing die photo, and generate the drawing take-up line profile based on the identified edge feature points of the drawing line.

[0011] Step S40: Compare the drawn drawing take-up line profile generated in step S30 with the pre-stored standard drawn drawing take-up line to determine whether the drawn drawing take-up line profile has an out-of-limit area.

[0012] Furthermore, it also includes step S50: if the judgment result of step S40 is that there is an over-limit area, then the control parameters of the stamping die are adjusted according to the deviation of the drawing take-up line profile.

[0013] Furthermore, the control parameters of the stamping die in step S50 include the blank holder force of the servo press and the height of the die's own balance block.

[0014] Furthermore, in step S20, when a signal indicating separation of the upper drawing die is received, an industrial camera is triggered to take a picture of the lower drawing die to ensure the industrial production cycle and to ensure that the industrial camera can accurately capture the entire drawing line.

[0015] Furthermore, in step S30, the edge feature points of the drawing line include multiple intersection points where the edge of the drawing line intersects with the grating mesh. The principle behind this design is that, in production practice, the edge of the drawing line is actually a three-dimensional spatial curve structure, not a planar structure. However, photos taken directly by industrial cameras will present this spatial curve structure as a planar structure, making it impossible to effectively extract the undulating three-dimensional edge line. Moreover, due to the small difference in pixel features between the mold and the workpiece, it is usually difficult to identify its edge. By projecting the grating mesh onto the surface of the lower drawing die, the grating mesh itself has a shape that undulates with the surface of the lower drawing die, thanks to the principles of light propagation and imaging. The intersection points of the drawing edge and the grating mesh are also easier to identify. By fitting these intersection points to generate the drawing edge profile, the actual shape of the drawing line edge of the drawing die can be better restored.

[0016] The present invention further provides an adaptive feedback adjustment system for a stamping die drawing take-up line, comprising a main control system, a grating projection device, an industrial camera, and a stamping die. The grating projection device is used to project a grating grid onto the drawing die of the stamping die. The industrial camera is used to capture a photograph of the lower drawing die. The main control system is used to control the actions of the grating projection device, the industrial camera, and the stamping die, and to determine whether there is an out-of-limit area in the drawing take-up line contour based on the photograph of the lower drawing die captured by the industrial camera.

[0017] Furthermore, the main control system includes a data receiving module, a drawing take-up line fitting module, an over-limit judgment module, and an output control module. The data receiving module receives the drawing die image transmitted by the industrial camera and the action signal fed back by the stamping die. The drawing take-up line fitting module identifies the edge feature points of the drawing line in the drawing die image and fits and generates the drawing take-up line profile based on the identified edge feature points. The over-limit judgment module compares the fitted drawing take-up line profile with the pre-stored standard drawing take-up line to determine whether the drawing take-up line profile exceeds the limit. The output control module controls the actions of the industrial camera, the grating photography device, and the stamping die.

[0018] Furthermore, it also includes a parameter adjustment module, which is used to adjust the control parameters of the stamping die when the judgment result of the over-limit judgment module is that there is an over-limit area. The control parameters of the stamping die include the blank holder force of the servo press and the height of the die's own balance block.

[0019] Furthermore, it also includes a storage module, which stores preset control strategy information based on the changes in the contour of the drawing take-up line. The control strategy information includes the adjustment method of the blank holder force of the servo press and the adjustment method of the height of the balance block of the die itself. The parameter adjustment module calls the corresponding control strategy information stored in the storage module according to the information of the over-limit area.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) The present invention adopts an original online measurement method, which can complete the adjustment of the stamping die drawing line without stopping the machine. The system is applicable to all dies and can save a lot of process and production costs compared with the existing measurement method that must be stopped offline.

[0022] (2) The adaptive feedback adjustment method of the present invention can realize continuous and uninterrupted measurement. Compared with the existing intermittent measurement (usually measured once every 200-300 pieces), it can obtain continuous production status data and more accurately control the stability of the production process.

[0023] (3) The adjustment method and system of the present invention have high measurement accuracy. Compared with the existing manual contact measurement, the accuracy is improved from mm level to 0.1 mm level; it can be connected to a servo press to realize closed-loop control and realize adaptive adjustment of the receiving line.

[0024] (4) The present invention adopts the rapid shooting form of industrial camera to avoid the impact of stamping vibration on measurement. Compared with the disadvantage of the traditional ATOS optical dimension scanning that cannot be measured in a vibration environment, it realizes the ability to measure on the stamping production site and reduces the safety hazards such as on-site scratches to 0. Attached Figure Description

[0025] Figure 1 The diagram shown is a field application illustration of the measurement method of the present invention.

[0026] Figure 2 As shown Figure 1 Schematic diagram of edge feature points of the middle drawing line. Detailed Implementation

[0027] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] It should be noted that in the following description, the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, in the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] Example 1:

[0030] This embodiment provides an adaptive feedback adjustment system for a stamping die drawing and take-up line, which includes a main control system, a grating projection device 210, an industrial camera 220, and a stamping die. Figure 1 In the illustrated embodiment, the stamping die includes a press worktable 121 and a drawing die 122 disposed on the press worktable 121. A grating projection device 210 and an industrial camera 220 are fixedly connected to the press column 112 via a shockproof bracket 230. Preferably, the grating projection device 210, the industrial camera 220, and the stamping die are connected to the system control cabinet 111 via a bus to receive overall control from the main control system. The grating projection device is used to project a grating grid onto the drawing die of the stamping die. The industrial camera is used to take a picture of the lower drawing die. The main control system is used to control the movement of the grating projection device, the industrial camera, and the stamping die, and to determine whether there is an out-of-limit area in the drawing take-up line contour based on the drawing die picture taken by the industrial camera.

[0031] In a preferred embodiment, the parameters such as the grating size, grating projection angle, and grating projection height projected by the grating projection device are all adjustable; the industrial camera 220 is a high-precision industrial camera, and its height relative to the drawing die 122 and its shooting angle are adjustable.

[0032] In a preferred embodiment, the grating grid includes a plurality of uniformly distributed squares, the side length of which is 3mm to 20mm; preferably, the side length of which is 5mm to 15mm; more preferably, the side length of which is 10mm.

[0033] In a preferred embodiment, the main control system includes a data receiving module, a drawing take-up line fitting module, an over-limit judgment module, and an output control module. The data receiving module receives a drawing die photograph transmitted by an industrial camera and motion signals from the stamping die. The drawing take-up line fitting module identifies edge feature points of the drawing line in the drawing die photograph and fits these feature points to generate a drawing take-up line profile. The over-limit judgment module compares the fitted drawing take-up line profile with a pre-stored standard drawing take-up line to determine if there is an over-limit region. The output control module controls the actions of the industrial camera, the grating photography device, and the stamping die. The over-limit region refers to the area where the error of the fitted drawing take-up line profile exceeds a preset tolerance threshold.

[0034] In a preferred embodiment, a parameter adjustment module is also included. The parameter adjustment module is used to adjust the control parameters of the stamping die when the judgment result of the over-limit judgment module is that there is an over-limit area. The control parameters of the stamping die include parameters such as the blank holder force of the servo press and the height of the die's own balance block.

[0035] In a preferred embodiment, a storage module is further included. The storage module stores preset control strategy information based on the changes in the contour of the drawing take-up line. The control strategy information includes the adjustment method of the blank holder force of the servo press and the adjustment method of the height of the balance block of the die itself. The parameter adjustment module calls the control strategy information of the corresponding change range in the storage module according to the information of the out-of-limit area.

[0036] In industrial practice, stamping dies typically use presses with multiple hydraulic cylinders to drive the stamping process on different areas of the drawn part. In a preferred embodiment, the drawing line profile of the area affected by each hydraulic cylinder is analyzed and judged. In the control strategy, the stamping force of the corresponding hydraulic cylinder is adjusted according to the drawing line area corresponding to the over-limit area to adjust the press blanking force of the corresponding part. Through this local adjustment method, more precise control of the drawing part production process can be achieved.

[0037] Example 2:

[0038] This embodiment provides an adaptive feedback adjustment method for the drawing take-up line of a stamping die, which includes the following steps:

[0039] Step S10: Trigger the grating projection device to project the grating grid onto the drawing die;

[0040] Step S20: Control the industrial camera to take a picture of the drawing die of the stamping die with a grating grid background;

[0041] Step S30: Receive the drawing die photo taken by the industrial camera, identify the edge feature points of the drawing line in the drawing die photo, and generate the drawing take-up line profile based on the identified edge feature points of the drawing line.

[0042] Step S40: Compare the drawn drawing take-up line profile generated in step S30 with the pre-stored standard drawn drawing take-up line to determine whether the drawn drawing take-up line profile has an out-of-limit area.

[0043] Step S50: If the judgment result of step S40 is that there is an over-limit area, then adjust the control parameters of the stamping die according to the deviation of the drawing take-up line. The control parameters of the stamping die include parameters such as the blank holder force of the servo press and the height of the die's own balance block.

[0044] In a preferred embodiment, to adapt to production cycle time and inspection time, in step S20, the triggering timing of the industrial camera is preferably set to trigger the industrial camera to take a picture of the lower drawing die after receiving a signal indicating the separation of the upper drawing die. This process can be set to take pictures every time the upper die separates after each drawn part is produced, or it can be set to take pictures at a certain time after the upper die separates after several drawn parts have been produced continuously. For example, pictures of the lower drawing die can be taken every 10 drawn parts produced, and the control parameters of the stamping die can be adjusted accordingly to balance production cycle time, adjust efficiency, and reduce resource consumption.

[0045] In a preferred embodiment, in step S30, the edge feature points of the drawn wire include multiple intersection points where the edge of the drawn wire intersects with the grating grid. For example... Figure 2 As shown, the grating projection device projects a grating onto the surface of the stamping and drawing die 122 to form a specific grating grid 211. The stamping die drawing take-up line L1 and the specific grating grid 211 form the edge feature information of the stamping die drawing take-up line (i.e., several spatial intersection points a / b / c / d / e). After being triggered, the high-precision industrial camera takes pictures and receives the edge feature information of the stamping die drawing take-up line (several spatial intersection points a / b / c / d / e). Connecting all the spatial intersection points forms the take-up line contour data through envelope fitting. Similarly, after the die has been running for a period of time, the drawing line may change due to machine operation heat, changes in ambient temperature, changes in lubricating oil film, etc. The changed stamping die drawing take-up line L2 and the specific grating grid 211 obtain the edge feature information of the changed stamping die drawing take-up line (spatial intersection points a' / b' / c' / d' / e'), which can be envelope fitted to form the changed take-up line contour data. The main control system can easily compare the contour data before and after the change. Based on the contour change database information of the take-up line and combined with the control strategy of the take-up line change range, the main control system actively outputs control signals and transmits them to the servo press through the Profinet network to adjust the blank holder force of the servo press. The change of the blank holder force of the servo press directly affects the contour of the take-up line, thus forming an adaptive adjustment closed loop, thereby ensuring that the error of the final produced drawn parts is within a controllable range.

[0046] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention; the dimensions described in the drawings and embodiments are not related to the specific physical object and are not used to limit the protection scope of the present invention. The physical dimensions can be selected and changed according to actual needs.

Claims

1. An adaptive feedback adjustment method for a stamping die drawing take-up line, characterized in that, Includes the following steps: Step S10: Trigger the grating projection device to project the grating grid onto the drawing die; Step S20: Control the industrial camera to take a picture of the drawing die of the stamping die with a grating grid background; Step S30: Receive the drawing die photo taken by the industrial camera, identify the edge feature points of the drawing line in the drawing die photo, the edge feature points of the drawing line include multiple intersection points where the edge of the drawing line intersects with the grating grid, and fit and generate the drawing take-up line profile based on the identified edge feature points of the drawing line. Step S40: Compare the drawn drawing take-up line profile generated in step S30 with the pre-stored standard drawn drawing take-up line to determine whether the drawn drawing take-up line profile has an out-of-limit area.

2. The method of adaptive feedback adjustment of a draw bead line in a stamping die of claim 1, wherein, It also includes step S50: if the judgment result of step S40 is that there is an over-limit area, then adjust the control parameters of the stamping die according to the deviation of the drawing take-up line.

3. The method of adaptive feedback adjustment of a draw bead line in a stamping die of claim 2, wherein, The control parameters of the stamping die in step S50 include the blank holder force of the servo press and the height of the die's own balance block.

4. The method of adaptive feedback adjustment of the drawing and blanking line of a stamping die according to any one of claims 1 to 3, characterized in that, In step S20, when a signal indicating separation of the upper die of the drawing die is received, an industrial camera is triggered to take a picture of the lower die of the drawing die.

5. An adaptive feedback adjustment system for a stamping die drawing and take-up line, characterized in that, The system includes a main control system, a grating projection device, an industrial camera, and a stamping die. The grating projection device projects a grating grid onto the drawing die of the stamping die. The industrial camera captures images of the lower drawing die. The main control system controls the movements of the grating projection device, the industrial camera, and the stamping die, and determines whether the drawing take-up line contour exceeds the limit based on the lower drawing die image captured by the industrial camera. The main control system includes a data receiving module, a drawing take-up line fitting module, an over-limit judgment module, and an output control module. The data receiving module receives the lower drawing die image transmitted by the industrial camera and the action signals fed back by the stamping die. The drawing take-up line fitting module identifies edge feature points of the drawing line in the lower drawing die image and fits and generates a drawing take-up line contour based on the identified edge feature points. The over-limit judgment module compares the fitted drawing take-up line contour with a pre-stored standard drawing take-up line to determine whether the drawing take-up line contour exceeds the limit. The output control module controls the movements of the industrial camera, the grating projection device, and the stamping die.

6. The stamping die draw neck-in line adaptive feedback adjustment system of claim 5, wherein, It also includes a parameter adjustment module, which is used to adjust the control parameters of the stamping die when the judgment result of the over-limit judgment module is that there is an over-limit area. The control parameters of the stamping die include the blank holder force of the servo press and the height of the die's own balance block.

7. The stamping die draw neck-in line adaptive feedback adjustment system of claim 6, wherein, It also includes a storage module, which stores preset control strategy information based on the changes in the contour of the drawing take-up line. The control strategy information includes the adjustment method of the blank holder force of the servo press and the adjustment method of the height of the balance block of the die itself. The parameter adjustment module calls the corresponding control strategy information from the storage module according to the information of the over-limit area.

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