FR3067645B1 - TOOLING OF STAMPING - Google Patents

Abstract

Sheet metal stamping tool comprising: a lower frame (102) with a counter-form (104) pivoting between a working position and a rest position for evacuation of the stamped part; an upper tool (110) adapted to cooperate with the counter-form (104) for producing an undercut; and a stop plate (106); remarkable in that the abutment plate (106) comprises a distal end provided with a roller (107), and in that the upper tool (110) comprises a cam (112) adapted to come into contact with the roller (107). ) during lowering of the upper frame, when the counter-form (104) is in the rest position or in any intermediate position between the rest position and the working position, the lowering of the tool (110) thus causing the pivoting the counter-form (104) to the working position.

Description

The invention relates to the field of stamping and relates more particularly to a tool for producing undercut forms.

The document FR 2 991 908 A1 discloses a tool for stamping sheet metal. It has a lower frame with a cylindrical cavity accommodating a counter-form pivotally mounted. An upper frame provided with an upper tool descends in translation. The counter-form is provided with a stop plate which angularly stops its movement. The upper frame then rises and the counter-form pivots to allow the evacuation of the stamped part. The pivoting of the counter-form is ensured by a pneumatic cylinder. In case of failure of this cylinder, the counter-form is not put in place properly before the descent of the upper frame. The upper tool then collides with the stop plate. This has the consequence of minimizing damage to both the tool, the counter-form and the stop plate. The invention aims to overcome at least one of the disadvantages of the state of the art mentioned above. More particularly, the object of the invention is to provide a stamping tool which ensures that no collision takes place in the event of a failure of the actuator which causes the counter-form to pivot. The invention also aims to provide a compact design, inexpensive, reliable and simple. The invention relates to a sheet metal stamping tool, comprising: a lower frame provided with a counterform pivoting between a working position for stamping an undercut in the stamping sheet and a position rest for evacuation of the stamped part; an upper frame provided with an upper tool capable of cooperating with the counter-form for producing the undercut; a stop plate, connected to the counter-form; a control actuator pivoting the counterform; remarkable in that the abutment plate comprises a distal end provided with a roller, and in that the upper tool comprises a cam adapted to come into contact with the roller during the descent of the upper frame, when the counter-form is in the rest position or in any intermediate position between the rest position and the working position, so that the descent of the tool causes the counterform to pivot to the working position.

The upper frame is configured to be movable in translation displacement by means of a stamping press on which the frames are then mounted.

According to an advantageous embodiment of the invention, the stop plate comprises an abutment face contained in a plane which is tangential to the outer surface of the roller. Thus, it is possible that the cam is also a bearing surface of the upper tool intended to come into contact with the stop plate. By this arrangement of the roller tangent to the plate, the upper tool comes into contact with the stop plate at the end of its stroke, when the counterform is actually positioned in its working position.

According to an advantageous embodiment of the invention, the roller has an outside diameter of between 1 and 8 cm.

According to an advantageous embodiment of the invention, the cam is a flat surface. Other cam profiles are conceivable in order to control the movement of the counter-form, for example to damp the end of travel and avoid the impact between the stop plate and the lower frame.

According to an advantageous embodiment of the invention, the stop plate has a length perpendicular to the axis of pivoting of the counter-form of between 10 and 30 cm, preferably between 15 and 20 cm.

According to an advantageous embodiment of the invention, the tooling comprises between 2 and 10 abutment plates parallel to each other, preferably 3 or 4. Counterforms can be independently controlled in pivoting. They can be aligned axially. A roller may be provided on more than one plate and corresponding cams may be provided on the upper tool. The plates can be evenly spaced in the direction of the axis of the counterform. The skilled person would adjust the position and the number of plate depending on the shape or dimensions of the part to be stamped. Thus, the lower frame may comprise several cavities each equipped with at least one counterform, each counterform having at least one abutment plate with a roller.

According to an advantageous embodiment of the invention, the control actuator is a pneumatic cylinder. Other actuators are conceivable, for example an electric motor, a hydraulic jack, etc. The latter will be provided with compensating means (springs, pressure relief valves, ...) to avoid damaging machine members when the movement of the counter-form is "forced" by the upper tool.

According to an advantageous embodiment of the invention, the angle between the rest position and the working position is between 20 and 90 °. The invention also relates to a method of shaping a sheet by stamping, comprising a step of stamping an undercut, the method being remarkable in that it employs the tooling according to one of the modes embodiment described above.

According to an advantageous embodiment of the invention, the stamping sheet is a body part of a motor vehicle.

The measures of the invention are interesting in that a malfunction of an actuator does not lead to degradation of the tooling. Other features and advantages of the present invention will be better understood with the help of the description and the drawings among which: FIG. 1 illustrates a tool according to the state of the art in working position; - Figure 2 illustrates a tool according to the state of the art in the rest position;

Figure 3 illustrates a tool according to the invention in the rest position; - Figures 4A to 4D illustrate the transition from the rest position to the working position in case of malfunction of the actuator.

Figure 1 shows a known tooling. It is a pressing press tooling. The tool comprises a lower frame 2, which comprises a cylindrical cavity 2.1 accommodating a counter-form 4 pivotable about the axis 2.2 of the cavity. A jack 5 drives counterform 4 pivotally. A stop plate 6 comes into position against the frame 2 in the working position shown in Figure 1. A sheet is placed on the surface 8 and overhanging the cavity 2.1. An upper tool goes down to deform the sheet. The upper tool descends to a working position where it can bear against the abutment plate 6 or against another stop not shown.

Figure 2 shows the same tool as Figure 1 but in the rest position. Once the undercut has been made in the sheet, the counterform 4 pivots under the influence of the cylinder 5 so that the sheet can be evacuated.

Figure 3 shows a preferred embodiment of the invention. The numbers are incremented by 100. The tool according to the invention comprises a lower frame 102 having a cylindrical cavity 102.1 of axis 102.2. The cavity 102.1 is open upwards. It accommodates a counterform 104 that can pivot about the axis 102.2 of the cavity. The counter-form pivots between a working position allowing the stamping of an undercut in the part to be stamped and a rest position allowing the evacuation of the stamped part. The angle swept between these two positions can be between 20 and 90 °, more particularly about 45 °. A cylinder 105 drives the counterform 104 pivotally. A sheet is placed on the surface 108 and overhanging the cavity 102.1. An upper tool 110 descends to deform the sheet. The counterform of FIG. 3 is not in its working position since the abutment plate 106 does not abut against the lower frame 2. This can occur when a malfunction occurs on the jack 105.

According to the invention, the abutment plate 106 is provided with a roller 107 at its distal end. Its distal end is the one that is at a distance from the counter-form 104. The roller is free to rotate about an axis parallel to the axis of pivoting of the counter-form. The tooling comprises an upper frame (not shown) on which is mounted an upper tool 110, provided with a cam 112 which is intended to come into contact with the roller 107. During the downward translation of the upper tool 110, the cam 112 will force the roller 107 in rotation and will drive against the form 104 pivoting. The upper tool 110 descends to a position where it bears against the abutment plate 6. The upper tool 110 also has a shape 114 at least partly complementary to the counter-form 104 to achieve the undercut in the stamping plate.

FIGS. 4A to 4D describe successive instants during the descent of the upper tool 110. In FIG. 4A, the upper tool 110 is in approach. The abutment plate 106 is in a position that is not the working position. This position may be the rest position, if a malfunction of the cylinder 105 has occurred after evacuation of the stamped part in the previous stamping cycle. The position of Figure 4A can also be any intermediate position if the cylinder 105 has failed after starting to move against the form.

FIG. 4B describes the moment when the upper tool 110 or more precisely the cam 112 of the tool 110 comes into contact with the roller 107. As the roller 107 is positioned at the distal end of the abutment plate 106, the cam 112 does not initially come into contact with the abutment plate 106. As the face 106.1 of the stop plate intended to come into contact with the cam 112 is contained in a plane which is tangential to the outer surface of the roller 107, 110 will not come into contact with the abutment plate 106 until the last moment of its movement. This avoids any unnecessary friction between the abutment plate 106 and the upper tool 110. In the illustrated embodiment, the cam 112 therefore has a dual function of contact with the roller 107 on the one hand and contact with the plate stop 106 on the other hand.

FIG. 4C illustrates a later moment of the descent of the upper tool 110.

FIG. 4D describes the end of travel of the upper tool 110. This instant coincides with the end of the contact between the cam 112 and the roller 107, and with the contact between the cam 112 and the abutment plate 106. This moment is also the one where the sheet is stamped and the form against undercut is obtained. Following this, the tool goes back up. The failure on the actuator 105 is repaired and the counterform is again placed in its rest position. The stamped part can be evacuated before or after the repair of the failure.

Claims (10)

1. Sheet metal stamping tool, comprising: - a lower frame (102) provided with a counter-form (104) pivoting between a working position for stamping an undercut in the sheet metal to be stamped and a rest position for evacuation of the stamped part; an upper frame provided with an upper tool (110) capable of cooperating with the counter-form (104) for producing the undercut; an abutment plate (106) connected to the counter-form (104); an actuator (105) for pivotally controlling the counterform (104); characterized in that the abutment plate (106) comprises a distal end provided with a roller (107), and in that the upper tool (110) comprises a cam (112) adapted to come into contact with the roller (107). ) during lowering of the upper frame, when the counter-form (104) is in the rest position or in any intermediate position between the rest position and the working position, so that the lowering of the tool (110) ) causes the counter-form (104) to pivot to the working position. 2. Tooling according to claim 1, characterized in that the abutment plate (106) comprises an abutment face (106.1) contained in a plane which is tangential to the outer surface of the roller (107). 3. Tooling according to one of claims 1 or 2, characterized in that the roller (107) has an outer diameter of between 1 and 8 cm. 4. Tooling according to one of claims 1 to 3, characterized in that the cam (112) is a flat surface. 5. Tooling according to one of claims 1 to 4, characterized in that the abutment plate (106) has a length perpendicular to the axis of pivoting of the counter-form between 10 and 30 cm, preferably between 15 and 20 cm. 6. Tooling according to one of claims 1 to 5, characterized in that it comprises between 2 and 10 abutment plates (106) parallel to each other, preferably 3 or 4. 7. Tooling according to one of claims 1 to 6, characterized in that the actuator (105) of control is a pneumatic cylinder. 8. Tooling according to one of claims 1 to 7, characterized in that the angle between the rest position and the working position is between 20 and 90 °. 9. A method of shaping a sheet by stamping, comprising a step of stamping an undercut, characterized in that it employs a tool according to one of claims 1 to 8. 10. The method of claim 9, characterized in that the stamping sheet is a body part of a motor vehicle.