Sheet metal stamping tooling with fiber optic detection device and process

Abstract

The invention relates to a stamping tool comprising an upper part for attachment to an upper frame and a lower part (24) for attachment to a lower frame; the upper and lower parts being adapted for stamping a sheet metal part (12) in a stamping press; the upper part comprising a stamping body with a lower face and an upper face (30) for receiving the sheet metal part (12) to be stamped; a vertical passage (32) passing through the stamping body from the upper face to the lower face. The lower part comprises an optical sheet metal detection device (34) arranged in the vertical passage; the optical detection device comprises at least one straight optical fiber (40) in the vertical passage. The stamped sheet metal forms a structural element of a motor vehicle. Figure to be published with the abbreviation: Figure 2

Description

Title of the invention: Sheet metal stamping tooling with optical fiber detection device and method

[0001] The invention relates to sheet metal stamping. More specifically, the invention concerns sheet metal detection in a sheet metal stamping tool using a stamping press. The invention relates to a stamping tool with a sheet metal detection device. The invention also relates to a stamping process.

[0002] The automotive industry requires the shaping of stamped sheet metal. This stamped sheet metal is formed in hydraulic presses to cut, curve, and locally stretch it in order to create the various functional surfaces of a motor vehicle's structure. Subsequently, this stamped sheet metal is assembled by welding or bonding and then receives a protective and finishing coating.

[0003] A stamping operation commonly requires a die on a fixed lower frame and a punch on a movable upper frame. Before the stamping operation, a blank sheet is received on the die in a reference position. Maintaining this reference position helps achieve the predefined geometry. To this end, the die includes guides that guide and then position the sheet when it is placed on it. Sensors are integrated to ensure that the sheet is indeed in position.

[0004] It is known to use magnetic sensors, such as inductive probes. However, these sensors are limited by their range, which is on the order of 10 mm. In some cases, these magnetic sensors cannot detect a correctly positioned sheet metal. Indeed, in some cases, before stamping, the sheet metal has a straight, raised shape relative to the area where the sensor is implanted. Or again, the sheet metal is roughed out with a bump extending away from the sensor. Such a scenario triggers a stoppage of the associated production line, which reduces output. Human intervention is then necessary to restart production.

[0005] The invention aims to address at least one of the problems or drawbacks encountered in the prior art. In particular, the invention aims to improve sheet metal detection in a stamping tool. The invention also aims to optimize the detection range, detection accuracy, compactness, quality of the stamped part, and ease of repair of a device for detecting a rough sheet of metal in a stamping tool, such as a rework tool.

[0006] According to a first aspect, the invention provides a stamping tool comprising an upper part intended to be fixed to an upper frame and a lower part intended to be fixed to a lower frame; the upper and lower parts being adapted for stamping sheet metal in a stamping press; the lower part comprising a stamping body with a lower face, an upper face intended to receive sheet metal to be stamped; a vertical passage through the stamping body from the upper face to the lower face; notable in that the lower part comprises an optical sheet metal detection device with at least one straight optical fiber in the vertical passage.

[0007] The invention installs an optical fiber in the lower part of the stamping tool to take advantage of the propagation distance of light rays. Furthermore, the straight nature of each optical fiber requires only a narrow passage and does not necessitate any adaptation of the stamping functional surfaces. Thus, the surface against which the sheet metal is protected remains intact despite the presence of the optical detection device. Sheet metal detection can be performed from critical points on the lower part since the sheet metal's grip and / or movement is minimally affected by the presence of the optical detection device.

[0008] Due to the diameter of an optical fiber, it is easy to add an optical detection device in a vertical passage of an existing stamping tool. The invention offers adaptability.

[0009] US6775888B1 describes a forming system for shaping parts, comprising a plurality of stations, at least one forming tool, and at least one machining device with a local power supply for machining the parts. The system is configured to be mobile in several planes and is arranged as a separate station within the forming system. However, this document does not provide an optical detection solution.

[0010] Preferably, the optical detection device includes an optical head receiving at least one straight optical fiber; the stamping tooling further includes a mounting support for the optical head in the vertical passage.

[0011] Preferably, the mounting support includes a vertical hole parallel to at least one straight optical fiber.

[0012] Preferably, the mounting support includes a lower housing for the optical head; and an upper conduit extending vertically from the lower housing; at least one straight optical fiber comprising an emitting optical fiber capable of emitting a light beam towards the sheet metal via the upper conduit, and a sensing optical fiber capable of receiving a light beam via the upper conduit.

[0013] Preferably, the mounting bracket includes a transverse hole with means for locking the optical head in the mounting bracket, the means for blocking being arranged in the transverse drilling.

[0014] Preferably, the mounting support comprises a cylindrical body with an upper surface and a lower surface; the optical head is arranged on the side of the lower surface.

[0015] Preferably, at least one straight optical fiber extends from the side of the lower surface.

[0016] Preferably, the optical head extends vertically under the lower surface.

[0017] Preferably, the vertical passage comprises an upper portion with a first diameter, and a lower portion with a second diameter smaller than the first diameter.

[0018] Preferably, the stamping tooling includes a remote guide for the optical detection device; and / or the stamping tooling includes at least: a punching unit, a cutting unit, or a bending unit.

[0019] Preferably, the optical detection device includes an amplifier coupled to at least one straight optical fiber.

[0020] Preferably, the amplifier includes means for adjusting a detection distance.

[0021] Preferably, the upper face of the stamping body comprises a stamping surface with a hollow, the vertical passage being in the hollow; preferably at the bottom of said hollow.

[0022] Preferably, at least half the length of at least one straight optical fiber is straight in the vertical passage.

[0023] Preferably, at least one straight optical fiber extends in a straight line in the vertical passage.

[0024] Preferably, at least one straight optical fiber is straight in the optical head.

[0025] Preferably, at least one straight optical fiber is configured to be opposite the sheet metal and / or generally perpendicular to the sheet metal.

[0026] Preferably, the cylindrical body is totally in the vertical passage.

[0027] Preferably, the optical head is totally housed in the vertical passage.

[0028] Preferably, the optical axis is arranged through the stamping body and / or the sheet metal.

[0029] Preferably, the amplifier is connected to the optical head.

[0030] Preferably, the optical detection device includes an optical head which is in the vertical passage and which receives at least one straight optical fiber.

[0031] Preferably, the stamping tooling is a rework tooling.

[0032] According to another aspect, the invention relates to a stamping tool comprising an upper part intended to be fixed to an upper frame and a lower part intended to be fixed to a lower frame; the upper and lower parts being adapted for stamping sheet metal in a stamping press; the lower part comprising a stamping body with a lower face, an upper face intended to receive the sheet metal to be stamped; a vertical passage through the stamping body from the upper face to the lower face; notable in that the lower part comprises an optical sheet metal detection device comprising at least one straight optical fiber, an optical head receiving at least one straight optical fiber in the vertical passage along an optical axis following the vertical passage.

[0033] According to another aspect, the invention proposes a method for stamping a sheet, the stamping method comprises the following steps: supplying a raw sheet; roughing a sheet by a first stamping of the raw sheet; then resuming the roughed sheet using a stamping tool; remarkable in that the stamping tool is in accordance with the invention, and in that at the resuming step the roughed sheet is vertically at a distance from the vertical passage.

[0034] Preferably, before the resumption step, the stamping process includes a step of detecting rough sheet metal by the optical detection device.

[0035] Preferably, the sheet metal is generally horizontal.

[0036] Preferably, the sheet metal covers the vertical passage.

[0037] According to another aspect, the invention relates to a method for detecting a sheet of metal in a stamping tool; remarkable in that the stamping tool conforms to the invention; and in that the stamping process comprises the following steps: supply or production of a sheet; insertion of the sheet into the stamping tool; analysis of the presence of the sheet in the tool by the optical detection device; then stamping of the sheet provided that the optical detection device detects said sheet.

[0038] According to another aspect, the invention proposes the use of a straight optical fiber to detect a sheet against a lower part of a stamping tool from a vertical passage between a lower face and an upper face of a stamping body of the lower part; the stamping tool being preferably in accordance with the invention.

[0039] Each feature introduced by the expression "preferably" given in relation to one of the aspects of the invention applies to all other aspects of the invention.

[0040] The invention will be well understood and other aspects and advantages will become clear upon reading the following description, given with reference to the attached figures listed below.

[0041] Figure 1 illustrates a stamping press with stamping tooling according to the invention.

[0042] Fig. 2 shows a portion of the lower part of a stamping tool according to the invention.

[0043] Fig. 3 is a plan view of a mounting support in a stamping tool according to the invention.

[0044] Figure 4 is a diagram of a sheet metal stamping process according to the invention.

[0045] In the following description, the term "include" is synonymous with "include" and is not limiting in that it permits the presence of other elements in the stamping tooling or other steps in the stamping process to which it relates. It is understood that the term "include" includes the terms "consist of".

[0046] In this description, the ranges of values ​​include the bounds that delimit them.

[0047] In the present description, equality between values ​​is not to be understood in the strict sense insofar as each equality allows a variation of at most 10%, preferably at most 5%, more preferably at most 2%, between these values.

[0048] In this description, the technical characteristics are defined in the mounting configuration of the stamping tooling, unless otherwise explicitly stated.

[0049] Throughout the description, the different figures use the same reference signs to designate identical or similar entities.

[0050] Fig. 1 represents a stamping press 10. The stamping press 10 is suitable for shaping a sheet 12, such as a sheet of steel or aluminum. Other alloys are also considered.

[0051] The stamping press 10 is integrated into a stamping installation comprising other stamping presses (not shown) performing other sheet metal forming operations on the sheet metal 12. Indeed, a stamped part is generally produced in several operations from a flat, raw sheet metal blank, usually called a sheet blank. Such a sheet blank commonly comes from a coil.

[0052] In order to shape the sheet metal 12 according to a predefined geometry, the stamping press 10 receives a stamping tool 14. The stamping tool 14 is interchangeable. The stamping tool 14 is mounted between a lower frame 18 and an upper frame 16. The upper frame 16 is movable between a lower position defining a closed position of the stamping tool 14, and an upper position defining an open position of the stamping tool 14. The open position allows the sheet metal 12 to be inserted, the closed position allows it to be stamped. The upper frame 16 is advantageously driven by a hydraulic cylinder 20. Stamping is a cold forming operation. It includes at least: local drawing, bending, cutting; or a combination thereof.

[0053] The stamping tool 14 comprises an upper part 22 fixed to the upper frame 16 and a lower part 24 fixed to the lower frame 18. The upper part 22 can be a punch. The lower part 24 can form a die. The lower part 24 has an impression of the shape to be produced. The upper part 22 and the lower part 24 have opposing surfaces. These surfaces are complementary. However, they have a gap corresponding to the thickness of the sheet metal 12. For example, the thickness of the sheet metal is between 0.50 mm and 1.00 mm. Thanks to their complementary surfaces, the upper part 22 and the lower part 24 are able to stamp the sheet metal 12 in a stamping press 10 according to a target shape.

[0054] The lower part 24 comprises a stamping body 26 with a lower face 28 and an upper face 30 on which the sheet metal 12 to be stamped is placed. The stamping body 26 is a single unit. It is metallic. It can generally form a plate with indentations and protrusions. The stamping body 26 further comprises a vertical passage 32 extending through it from the upper face 30 to the lower face 28. The vertical passage 32 is open.

[0055] The lower portion 24 further includes a sheet metal optical detection device 34 with a straight fiber optic cable. The optical detection device 34 is a presence sensor. It is housed and sheltered within the vertical passage 32. Thus, the optical detection device 34 is protected. According to one option, the lower portion 24 includes several optical detection devices 34 arranged in several vertical passages 32 distributed beneath the sheet metal. A control unit (not shown) of the stamping press 10 enables or prevents the stamping tool 14 from closing based on a sheet metal detection criterion 12 by all the optical detection devices 34.

[0056] According to one option of the invention, the stamping tool 14 is a rework tool.

[0057] The stamping tool 14 may include one or more pressers. The pressers hold the sheet metal 12 before and during stamping. They allow control of the sliding of the sheet metal 12 during its stretching.

[0058] The stamping tool 14 comprises: a punching unit, a cutting unit, or a bending unit (not shown). These units are advantageously combined to cut around a part, drill it locally, and form inclined tabs in it in a single operation of closing the stamping tool 14.

[0059] Stamped sheet metal can be used to form a structural element of a motor vehicle. For example, sheet metal can be used to form a lining for an opening, such as a hood or side door lining. It can form part of a side member or crossmember, or Another floor element. The sheet metal could be a bodywork element.

[0060] Figure 2 shows a lower portion 24 of a stamping tool. The stamping tool corresponds to that shown in relation to Figure 1. The upper portion is not shown for clarity.

[0061] A sheet 12, having undergone at least one preliminary stamping operation, is placed on the lower part 24. The sheet 12 covers the vertical passage 32. The sheet 12 is a roughed-out sheet 36. The roughed-out sheet 36 has at least one curvature, for example, a basin shape generated by stretching along two intersecting directions. The lower part 24 may include a guide 38. The guide 38 is also called a pilot. It guides the sheet 12 to its stamping position against the upper face 30. The optical detection device 34 is vertically offset from the guide 38, which increases the gap between the sheet 12 and the optical detection device 34.

[0062] The optical detection device 34 comprises at least one straight optical fiber 40; preferably at least two straight optical fibers 40. The optical detection device 34 comprises an optical head 42 receiving each straight optical fiber 40, in particular their upper ends. The optical head 42 improves the orientation of each straight optical fiber 40 in the vertical passage 32, and thus towards the sheet metal 12. The emission and detection direction of the straight optical fibers 40 is along their direction of entry into the optical head 42.

[0063] The optical head 42 comprises an optical axis 44 arranged along the vertical passage 32. The optical axis 44 is the axis along which light rays propagate out of and into the straight optical fibers. The optical axis 44 is parallel to the vertical passage 32, or inclined at most 20°, preferably at most 10°, more preferably at most 5° with respect to the vertical passage 32. The optical axis 44 is along each straight optical fiber 40. It corresponds to the direction of entry and / or exit of the light ray, also called the light beam 54, in the straight optical fibers 40.

[0064] The optical detection device 34 improves compactness since the straight optical fibers 40 are inline, thus requiring little space for integration into the stamping tooling. Consequently, the internal diameter of the vertical passage 32 remains limited. The diameter of each straight optical fiber is less than or equal to 2.00 mm, preferably 1.00 mm. It can be less than or equal to the thickness of the sheet metal.

[0065] The stamping tooling further includes a mounting bracket 46 for the optical head 42 in the vertical passage 32. The mounting bracket 46 allows for precise positioning of the optical head 42 relative to the lower part 24, and therefore relative to a theoretical position of the sheet metal 12. Thus, the detection accuracy of the optical detection device 34 is optimal. In addition, the mounting bracket 46 facilitates the removal of the optical head 42 since it provides additional interfaces for assembly. Thus, the optical detection device 34 can be replaced without dismantling all the stamping tooling; and therefore without requiring new adjustments.

[0066] The mounting support 46 includes a lower housing 48 for the optical head 42; and an upper conduit 50 extending vertically from the lower housing 48. The optical head 42 is connected to an emitting optical fiber 52 capable of emitting a light beam 54 towards the sheet metal 12 via the upper conduit 50, and a detecting optical fiber 56 capable of receiving a light beam 54 via the upper conduit 50. This upper conduit 50 is a common optical conduit.

[0067] The mounting bracket 46 comprises a cylindrical body 58 with an upper surface 60 and a lower surface 62. The optical head 42 is arranged on the side of the lower surface 62. The transmitting optical fiber 52 and the sensing optical fiber 56 extend downwards from the side of the lower surface 62. The optical head 42 protrudes below the lower surface 62.

[0068] The vertical passage 32 comprises an upper portion 64 with a first diameter 66, and a lower portion 68 with a second diameter 70 smaller than the first diameter 66. This arrangement allows for positioning and retention of the mounting bracket 46, or more generally of the optical detection device 34. The mounting bracket 46 is held in the vertical passage 32 by means of clamping means 72.

[0069] The upper face 30 comprises a stamping surface with a recess 74. The recess 74 forms a basin. The vertical passage 32 is positioned within the recess 74. Preferably, the vertical passage 32 is positioned at the bottom of the recess 74. It is at the lowest point of the recess 74. Thus, the sheet metal 12 is vertically distant from the highest point of the vertical passage 32. This feature complicates detection. However, the arrangement and properties of the optical head 42 facilitate and ensure the detection of the sheet metal despite the significant distance.

[0070] The optical detection device 34 includes an amplifier 76 which is coupled to the optical head 42 via at least one straight optical fiber 40. The amplifier 76 includes a light source (not shown) coupled to the transmitting optical fiber 52, and a photosensitive sensor (not shown) coupled to the detecting optical fiber 56. The amplifier 76 includes means 78 for adjusting the detection distance. The adjustment means are configured to increase the light intensity emitted by the light source and / or the sensitivity threshold of the photosensitive sensor. Thus, it is possible to modulate the detection distance from 5 mm to 70 mm, thereby extending the detection area and preventing false detections of sheet metal, or ensuring detection reliability. Following a comparison of the received light intensity with the intensity threshold, the amplifier is capable of emitting a presence signal if necessary.

[0071] For example, the optical detection device includes an optical fiber of reference TLG 100-K1-M-500 from the company Pepperl and Fuchs.

[0072] According to an alternative embodiment of the invention, at least one straight optical fiber comprises a single sensing optical fiber. In this case, an external light source outside the vertical passage and illuminating the sheet metal 12 is used. Such a light source can then be common to several optical sensing devices.

[0073] According to another alternative, the single straight optical fiber is a transmitting optical fiber. In this configuration, photosensitive detection means are outside the vertical passage.

[0074] Figure 3 shows a mounting bracket 46 for an optical head 42 of a sheet metal optical detection device for a stamping tool. The stamping tool corresponds to that shown in relation to one of Figures 1 to 2. The upper surface 60 of the mounting bracket 46 is in the foreground.

[0075] The mounting bracket 46 includes a lower housing 48 for the optical head 42; and an upper conduit 50 extending vertically from the lower housing 48. The optical head 42 is circular. Its diameter is substantially equal to that of the lower housing 48. The upper conduit 50 is open upwards. The optical head 42 receives the transmitting optical fiber 52 and the detecting optical fiber 56. These are respectively capable of emitting a light beam towards the sheet metal and of capturing a reflection of this same light beam via the upper conduit 50.

[0076] The mounting bracket 46 is an adapter. The mounting bracket 46 includes a transverse bore 80 with locking means 82 for the optical head 42 within the mounting bracket 46. The locking means 82 are arranged within the transverse bore 80. The transverse bore 80 communicates with the lower housing 48. Thanks to this configuration, the locking means 82 are protected in the vertical passage. Their presence in the transverse bore prevents their loss in the event of loosening, which is itself prevented by their protection within the core of the mounting bracket 46.

[0077] The mounting bracket 46 includes a vertical hole 84 parallel to at least one straight optical fiber 40. The vertical hole 84 facilitates disassembly of the mounting bracket 46. It may include a thread. It is opposite the transverse hole 80. The parallelism between each straight optical fiber 40 and the vertical hole 84 allows disassembly without damaging the fibers.

[0078] Figure 4 shows a diagram of a stamping process with tooling stamping. The stamping tooling corresponds to that shown in relation to one of figures 1 to 3.

[0079] The stamping process comprises the following steps:

[0080] supply 100 of a raw sheet such as a flat sheet blank;

[0081] rough 102 of a sheet metal roughed out by a first stamping of the raw sheet metal; then

[0082] reworking 106 of the roughed sheet metal using a stamping tool.

[0083] At the resumption step 106, the rough sheet metal is vertically at a distance from the vertical passage, for example a vertical distance of between 5 mm and 70 mm.

[0084] According to one option, the stamping process includes a sheet metal detection step 104 by the optical detection device before the resumption step 106. Also according to this option, the process further includes a stop step 108 of the stamping press in case of no sheet metal detection by the optical detection device.

[0085] The detection step 104 can be a step for analyzing the presence of sheet metal in the stamping tooling. Specifically, the amplifier generates an electrical signal which is analyzed by computer means on a control panel of the stamping press. The computer means compares the electrical signal to a threshold presence criterion; and concludes that sheet metal is present when the presence criterion is not met.

[0086] The stamping process can be a sheet metal detection process which conditions the stamping operation on the detection of a sheet metal by the optical detection device.

[0087] The invention comprises the combination of all the embodiments presented by all the figures.

Claims

Demands

1. Stamping tooling (14) comprising an upper part (22) intended to be fixed to an upper frame (16) and a lower part (24) intended to be fixed to a lower frame (18); the upper and lower parts (24) being adapted for stamping a sheet (12) in a stamping press (10); the lower part (24) comprising a stamping body (26) having a lower face (28), an upper face (30) intended to receive the sheet (12) to be stamped; a vertical passage (32) passing through the stamping body (26) from the upper face (30) to the lower face (28); characterized in that the lower part (24) comprises an optical detection device (34) for sheet (12) having at least one straight optical fiber (40) in the vertical passage (32).

2. Stamping tool (14) according to claim 1, characterized in that the optical detection device (34) comprises an optical head (42) receiving at least one straight optical fiber (40); the stamping tool (14) further comprises a mounting support (46) for the optical head (42) in the vertical passage (32); preferably, the mounting support (46) comprises a vertical bore (84) parallel to at least one straight optical fiber (40).

3. Stamping tooling (14) according to claim 2, characterized in that the mounting support (46) comprises a lower housing (48) for the optical head (42); and an upper conduit (50) extending vertically from the lower housing (48); at least one straight optical fiber (40) comprising an emitting optical fiber (52) capable of emitting a light beam (54) towards the sheet metal (12) via the upper conduit (50), and a sensing optical fiber (56) capable of receiving a light beam (54) via the upper conduit (50).

4. Stamping tool (14) according to any one of claims 2 to 3, characterized in that the mounting support (46) comprises a transverse bore (80) with locking means (82) for the optical head (42) in the mounting support (46), the locking means (82) being arranged in the transverse bore (80).

5. Stamping tool (14) according to any one of claims 2 to 4, characterized in that the mounting support (46) comprises a cylindrical body (58) with an upper surface (60) and a lower surface (62); the optical head (42) is arranged on the side of the lower surface. lower (62); preferably the optical head (42) extends vertically below the lower surface (62).

6. Stamping tool (14) according to any one of claims 1 to 5, characterized in that the vertical passage (32) comprises an upper portion (64) with a first diameter (66), and a lower portion (68) with a second diameter (70) smaller than the first diameter (66).

7. Stamping tooling (14) according to any one of claims 1 to 6, characterized in that the stamping tooling (14) comprises a guide (38) at a distance from the optical sensing device (34); and / or the stamping tooling (14) comprises at least: a punching unit, a cutting unit, or a bending unit.

8. Stamping tooling (14) according to any one of claims 1 to 7, characterized in that the optical detection device (34) comprises an amplifier (76) coupled to at least one straight optical fiber (40); preferably, the amplifier (76) comprises means for adjusting (78) a detection distance.

9. Stamping tool (14) according to any one of claims 1 to 8, characterized in that the upper face (30) of the stamping body (26) comprises a stamping surface with a hollow (74), the vertical passage (32) being in the hollow (74); preferably at the bottom of said hollow (74).

10. A method for stamping a sheet (12), the stamping method comprising the following steps: supplying (100) a blank sheet; roughing (102) a blank sheet (36) by a first stamping of the blank sheet; then resuming (106) the blank sheet (36) using a stamping tool (14); characterized in that the stamping tool (14) conforms to any one of claims 1 to 9, and in that at the resuming step (106) the blank sheet (36) is vertically at a distance from the vertical passage (32); preferably, before the resuming step (106), the stamping method comprises a detection step (104) of the blank sheet (36) by the optical detection device (34).

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