Deep drawing press and method for detecting a sheet metal waste jam

Description

technical field

[0001] The invention relates to the field of stamping, and more particularly to the removal of stamping scrap. Previous technique

[0002] A stamping press is used, in particular, to manufacture automotive parts by cutting sheet metal and shaping it through stamping. Cutting sheet metal with the stamping press produces, on the one hand, a blank of the required size and, on the other hand, excess sheet metal, commonly referred to as scrap. The blank of the required size will be used to manufacture the finished part, while the excess scrap is cut off and removed by falling along the sides of the die into the pit or the floor of the stamping press.

[0003] Today, stamping processes are carried out by automated presses and robots, because their combined use makes it possible to carry out the process simply and safely, as well as to configure the stamping parameters according to the needs of the parts and sheets.

[0004] However, current automatic stamping presses are prone to jamming caused by the accumulation of scrap throughout the manufacturing process. The combined size of the scrap and the pressure exerted can damage the die. Over time, the scrap accumulates and presses against each other due to the pressing cycles, making it more difficult to remove. Furthermore, this accumulation of scrap remaining in the die causes the sheet metal or part to rise excessively, potentially leading to the robot failing to detect the working position and resulting in production stoppages.

[0005] The published patent document US 2016 / 0175911 A1 discloses a method for stamping a part comprising recording said part by cameras in such a way as to detect and compare parameters from the images obtained via said cameras, with pre-recorded parameters.

[0006] However, although the solution in US document 2016 / 0175911 A1 aims to improve the quality of stamped parts with continuous monitoring of the stamping process, it does not address the problem of scrap jamming. Description of the invention

[0007] The present invention aims to overcome at least one of the drawbacks of the aforementioned prior art. More specifically, the invention aims to provide a simple, efficient, and economical solution for preventing the accumulation of scrap throughout the stamping process in order to avoid any risk of jamming.

[0008] To this end, the invention relates to a method for controlling sheet metal stamping on a stamping press, with robotic loading of the sheet metal onto the stamping press, closing of said stamping press with cutting of offcuts, and robotic unloading of said sheet metal from the stamping press, said method comprising the steps: detection of possible fall protection failures; issuance of an alarm in the event of confirmed fall protection failure; remarkable in that fall protection failure detection includes: an acquisition of images of at least one chute for evacuating scrap and / or at least one collection bin for said scrap, on the stamping press; and an analysis of said images in order to identify any possible defect in evacuation of scrap.

[0009] According to one embodiment, the stamping press comprises a main, stationary frame, with image acquisition being carried out via a camera fixed to said frame.

[0010] According to one embodiment, the stamping press comprises a lower, fixed frame and an upper frame that is vertically movable, the camera being located above a higher level of the lower frame and laterally to the upper frame.

[0011] According to one embodiment, the image analysis includes the determination of at least one area of ​​interest corresponding to at least one chute and / or at least one tray.

[0012] According to one embodiment, image acquisition and / or image analysis takes place specifically between the end of the closing and the end of the opening following said closing of the stamping press.

[0013] According to one embodiment, the image acquisition between the end of the closing and the end of the successive opening of the stamping press includes an acquisition of at least two images.

[0014] According to one embodiment, image analysis concludes that there is a failure to evacuate falls when a fall is detected as immobile in one of at least one evacuation chutes.

[0015] According to one embodiment, image analysis concludes that there is a failure to evacuate waste when no waste is detected in at least one evacuation chute between an end of closure and an end of opening successive to said closure of the stamping press.

[0016] The invention also relates to a sheet metal stamping press comprising: a main, fixed chassis; a lower frame, fixed with the chassis; an upper frame, movable vertically relative to the chassis and the lower frame; a movement control unit for the upper frame, for closing and opening the stamping press; remarkable in that said stamping press further comprises: a camera disposed above the lower frame and laterally to the upper frame so as to be able to acquire images of a sheet metal cutting die with at least one chute for evacuating offcut(s) of said sheet metal; an image processing unit; the control unit, the camera and the image processing unit being configured to carry out the process according to the invention.

[0017] According to one embodiment, the image processing unit is operationally connected to the control unit so as to stop the stamping press in the event of detection of a failure to evacuate the waste.

[0018] Advantageously, the sheet metal stamping control process on the stamping press of the present invention makes it possible to avoid the accumulation of sheet metal scraps during the stamping process, thus avoiding any risk of jamming which could damage the stamping press and / or its components.

[0019] The invention also makes it possible to further secure the manufacture of stamped sheet metal parts, and to ensure better control of production time and costs. Brief description of the drawings

[0020] [ Fig 1 ] represents a schematic perspective view of a sheet metal stamping press configured to perform a stamping control process according to the invention. Detailed description

[0021] There figure 1 represents a sheet metal stamping press 2 comprising a fixed main frame 4 with a lower frame 6 on which is fixed a sheet metal cutting die 8 10 to be stamped.

[0022] The press 2 includes an upper frame 12 movable vertically (along the Z axis) relative to the frame 4 and the lower frame 6. For this purpose, we speak of closing or opening the stamping press 2 when the upper frame 12 is, respectively, in a low or high position relative to the lower frame 6.

[0023] The movements of the upper frame 12 are automated and managed by a control unit 14, preferably corresponding to an industrial programmable logic controller 14, which will be designated by a PLC 14 in this description.

[0024] Preferably, the cutting die 8 includes at least one chute 16 for removing waste 18, and more preferably a multitude of chutes 16. For example, one can see on the figure 1 that matrix 8 comprises seven chutes extending over at least 70% of a longitudinal extent (along the X axis) of matrix 8, and having an inclination of at least 20° with a horizontal plane.

[0025] In this configuration, the 18 scraps are able to be evacuated from the die 8 by gravity to bins 20 arranged on the two lateral sides of the press 2.

[0026] The press 2 further includes a camera 22 arranged above the lower frame 6 and laterally to the upper frame 12. Such an arrangement of the camera 22 enables it to acquire matrix images 8.

[0027] Preferably, the camera 22 corresponds to a 2D monochrome camera connected to a computer 24 which can correspond to a human-machine interface, called HMI 24.

[0028] Computer 24 corresponds to an image processing unit 24 preferably including standard image processing software for vision systems. Preferably, the software includes processing algorithms provided by HALCON®.

[0029] In this configuration, communication between camera 22 and computer 24 is preferably ensured by an Ethernet network (link illustrated by dotted arrows) in order to allow fast transmission of images captured by camera 22.

[0030] Similarly, the camera 22 is also connected to the PLC 14 via the Ethernet network so as to allow the transmission of an identification signal of a reference of the sheet metal part 10. Advantageously, the identification of the reference of the part 10 makes it possible to avoid any risk of interference between at least one robot 26 and the acquisition of images by the camera 22.

[0031] Indeed, the manufacturing process of parts 10 is robotized by means of at least one industrial robot 26 corresponding to an articulated arm with a gripper (not shown) allowing the placement of the sheet metal 10 onto the die 8. The stamping press 2 may also include a second robot (not shown) located on the other side of the press 2 and ensuring the removal of the parts 10 after they have been stamped.

[0032] Computer 24 is operationally connected to PLC 14 in order to stop the stamping press 2 in the event of detection of a possible failure of evacuation of the waste 18 by the camera 22. In this regard, the camera 22 and the computer 24 are configured to execute a stamping control process allowing to protect the press 2 from any risk of jamming which may be caused by the waste 18.

[0033] The stamping inspection process includes an image acquisition step of at least one area of ​​interest corresponding to at least one chute 16 and / or at least one tray 20. Preferably, each area of ​​interest corresponds to the chute 16. For this purpose, the camera 22 is capable of capturing images of each of the seven chutes 16 illustrated in the figure 1 .

[0034] Image acquisition includes the analysis of at least two images during a stamping cycle, and specifically between the end of the closing and the end of the successive opening of the stamping press 2, the number of images captured can be up to 10 images.

[0035] Preferably, the movement of the robot 26 is synchronized with the raising and lowering of the upper frame 12 of the press 2, so that when the press opens, the gripper of the robot 26 grasps the part 10 to remove it, and subsequently positions another part or sheet before the press 2 closes to perform the next stamping cycle.

[0036] In this configuration, the time between the moment when the press 2 opens and the moment when the robot 26 positions the next part is sufficient to capture a multitude of images in order to analyze the presence of the drops 18.

[0037] In this regard, the process of the invention performs the analysis of the images captured by the camera 22 during the stamping cycle, in order to identify the possible defect in the evacuation of the scrap 18.

[0038] Image analysis includes, firstly, the determination of areas of interest. In this respect, the process interprets the moment of image capture, since it detects the position of the press 2, recognizes the reference of the part to be analyzed and ensures that the robots 26 are outside the area of ​​interest and do not interfere with image acquisition.

[0039] In this configuration, the camera 22 covering all the chutes 16 requires good lighting to prevent any dark areas from appearing in the evacuation chutes 16 or areas of excessive brightness from being confused with the drops 18, leading to erroneous results.

[0040] Advantageously, the camera 22 can be configured according to the matrix 8, taking into account the position of the various drainage channels 16. In this respect, correct adjustment of the orientation of the camera 22 may be necessary.

[0041] The method of the invention executes, in parallel with the acquisition of images during the cycle, the execution of image processing algorithms by the computer 24.

[0042] Indeed, at the moment when the press 2 opens, after stamping the part 10, this is the moment when the scraps 18 must fall into the bin 20 by means of the chutes 16. At this stage, the images captured in the areas of interest are analyzed and evaluated by the software, in order to verify that the scraps 18 have followed a normal fall pattern / path, said normal pattern preferably corresponds to a progressive fall of the scrap 18 which may correspond to an appearance and a disappearance of the scrap 18, respectively, between a first image and a last image captured at the end of the cycle, the software also verifies that no scrap 18 has remained blocked at the right of at least one of the chutes 16.

[0043] Advantageously, the software is able to adapt to the type of part to be stamped, because depending on the reference of the parts produced, the scraps 18 can fall in different places relative to the die 8 (through a top part for example), and with different sizes depending on the morphology of the parts to be stamped.

[0044] To this end, the software is able to adjust, in particular according to lighting conditions, the areas of interest used for the evaluation of the falls 18, because these areas are specific to each matrix 8 (and to each part 10).

[0045] Once the images have been processed, the software concludes that there is a failure to evacuate the waste 18 when a waste 18 is detected as immobile in one of the evacuation chutes 16 (appearance of the waste 18, respectively, in the first image and the last image captured at the end of the cycle by the camera 22), and / or when no waste 18 is detected in one of the chutes 18 between an end of the closing and an end of the opening of the press 2 (no presence of waste 18 between the first image and the last image captured at the end of the cycle).

[0046] In the event of a defect in the evacuation of the waste 18 being determined, the method of the invention shall emit a warning signal, preferably by means of a signal lamp 28 and / or an audible alarm, to signal the stoppage of the press 2 in order to allow manual intervention by an operator or by the robot 26 to stop the jamming and evacuate the waste 18 concerned.

[0047] Alternatively, if no fault is detected in the evacuation of the falls 18, a signal of proper operation may be emitted by signal lamp 28.

[0048] Preferably, computer 24 includes a screen capable of displaying images captured during stamping cycles as well as the reference of the parts to be stamped, in order to ensure visual monitoring of the process.

[0049] Advantageously, the operational link between computer 24 and PLC 14 allows the latter to stop stamping press 2 in the event of detection of a fault in the evacuation of the waste 18, in order to preserve the press 2 and its components from any risk of damage which may be caused by a possible jam, thus improving the safety and longevity of the machines and people.

Claims

1. Method for checking the stamping of sheet metal (10) on a stamping press (2), with robotized load of the sheet metal (10) on the stamping press (2), closure of said stamping press (2) with cut-out (18), and robotized unloading of said sheet metal (10) on the stamping press (2), said method comprising the steps of: - detection of a possible fall escape defect (18); - issuing an alarm in the event of a proven detection of a fall evacuation defect (18); characterised by fall escape defect detection (18) includes: - acquisition of images of at least one discharge chute (16) for the falls (18) and / or at least one recovery tank (20) for said falls (18), on the stamping press (2); and - an analysis of these images in order to identify the possible defect of evacuation of the falls (18).

2. Method according to claim 1, in which the stamping press (2) comprises a main and stationary frame (4), the acquisition of the images being realised via a camera (2) fixed to said frame (4).

3. Method according to claim 2, in which the stamping press (2) comprises a stationary lower frame (6) and a vertically movable upper frame (12), the camera (22) being located above an upper level of the lower frame (6) and laterally to the upper frame (12).

4. Method according to one of Claims 1 to 3, in which the analysis of the images comprises a determination of at least one zone of interest corresponding to the at least one chute (16) and / or to the at least one tray (20).

5. Process according to one of Claims 1 to 4, in which the acquisition of images and / or the analysis of the a / a images take location specifically between an end of the closure and an end of opening successive to the said closure of the stamping press (2).

6. Method according to claim 5, in which the acquisition of images between the end of the closure and the end of the successive opening of the stamping press (2) comprises an acquisition of at least two images.

7. Method according to one of Claims 1 to 6, in which the analysis of the images concludes with a defect for evacuating the falls (18) when a fall is detected as immobile in one of the at least one evacuation chute (16).

8. Method according to one of Claims 1 to 7, in which the analysis of the images concludes with a defect for evacuating the scraps (18) when no scraps (18) are detected in one of the at least one evacuation chute (18) between an end of the closure and an end of opening successive to said closure of the stamping press (2).

9. Sheet metal (10) stamping press (2) comprising: - a chassis (4), main and stationary; - a lower frame (6), fixed with the frame (4); - an upper frame (12), movable vertically by report to the frame (4) and to the lower frame (6); - a unit (14) for controlling the movement of the upper frame (12), closing and opening the stamping press (2); wherein the stamping press (2) further comprises: a camera (22) arranged above the lower frame (6) and laterally to the upper frame (12) so as to be able to acquire images of a die (8) for cutting the sheet (10) with at least one discharge chute (16) for dropping (18) said sheet (10); - a processing unit (24) of the images; the control unit (14), the camera (22) and the image processing unit (24) being configured to execute the method according to one of claims 1 to 8.

10. stamping press (2) according to Claim 9, in which the image processing unit (24) is operatively connected to the control unit (14) so as to stop the stamping press (2) in the event of detection of a defect for evacuating the falls (18).