EP3538292B1 - Press tooling for sheet metal of relatively large dimensions, notably for motor vehicles - Google Patents

Description

The present invention relates to a press tool and more particularly relates to a tool for stamping sheets, in particular relatively large metal blanks used in the automotive industry.

A stamping tool is known comprising a fixed table on which rests a base called the mobile rolling plate on which a punch is fixed. This tool further comprises a hydraulic stamping cushion housed under the base, a blank holder located above the base and comprising, integral with the latter, vertical columns at lower ends comprising bobéchons resting respectively on the ends. upper of vertical stamping rods or candles passing through holes in the base and the lower ends of which bear on the stamping cushion.

The stamping tooling also comprises an upper frame supporting a die capable of moving vertically towards the blank holder, the latter and the die respectively comprising two surfaces between which the blank is clamped for the stamping phase.

The stamping rods are able to transmit the clamping force of the cushion to the blank holder via the bobechons and the columns of the blank holder while the die descends on the blank holder so as to allow the blank to 'be clamped between the two bearing surfaces of the blank holder and the die before the stamping operation of this blank.

The document FR3008330 describes a press tool comprising a die movable vertically towards a fixed punch supported by a lower frame, the punch being surrounded by a blank holder designed to be able to clamp the periphery of the blank to be stamped against the die before the closed position of the die. tooling thanks to the thrust exerted by the candles, comprising between the blank holder and the candles a lifting beam making it possible to increase the application surface of the supports of the candles, and thereby to obtain an optimal clamping force, in case of large parts.

The surface of the blank holder must be perfectly homogeneous to ensure homogeneous clamping of the blank between the surfaces of the blank holder and the die, the regulation of supplying the blank and guaranteeing the quality of the stamped part on any press manufacturing the same model.

To obtain a correct blank holder reach, it is carried out by grinding and finalized by honing at a toolmaker. When transferring the tools to the site where the production press is located, the adjustment carried out at the toolmaker must be found in order to preserve the drawability and quality of the stamped parts.

However, the presses of the same model and the same brand are not strictly identical, leading to a non-homogeneity or shift in the reach of the blank holder, so that a new adjustment is essential to find a tightening of the clamp. blank on the press identical to that obtained from the toolmaker. Until now, this adjustment has been carried out by grinding and honing in the same way as grinding and honing at the toolmaker. This new adjustment is long, expensive and generates pollution on the production line following the projections of filings and grinding grains.

The object of the present invention is to overcome the above drawbacks of the prior art.

To this end, the invention provides a tool for stamping a blank for forming a stamped part, in particular of a motor vehicle, comprising a lower base fixed on a support table and comprising a punch, a cushion stamping housed under the support table, a blank holder located above the base and comprising vertical columns at lower ends comprising bobéchons resting respectively on upper ends of vertical stamping rods passing through holes in the base and of the support table and the lower ends of which bear on the stamping pad, a slide supporting a die capable of moving vertically towards the blank holder, the latter and the die respectively comprising two bearing surfaces between which can be clamped the blank, the stamping rods being able to transmit the clamping force of the stamping cushion within the reach of the blank holder, and which is characterized in that e the vertical columns of the blank holder each comprise between its end and the corresponding bobechon at least one foil allowing elastic deformation of the blank holder by the stamping pad and the stamping rods to ensure uniform clamping of the blank over any the scope of the blank holder.

Each bobéchon is removably fixed by screwing to the end of the corresponding vertical column of the blank holder and the foil can be fixed by clamping between the bobéchon and the end of the vertical column of the blank holder.

The thickness of the foil is between 1/10 mm and 1 mm depending on the stamping tool used.

The vertical columns comprising the foils are located opposite a zone of the bearing surface of the blank holder having a surface deviation relative to the remaining homogeneous surface of the bearing surface.

• La figure 1 est une vue en perspective éclatée d'une partie de l'outillage d'emboutissage de l'invention et occupant une position ouverte avant serrage d'un flan ;
• la figure 2 est une vue schématique représentant une partie complémentaire de l'outillage d'emboutissage de la figure 1 ;
• la figure 3 est une vue partielle en coupe de la partie inférieure de l'outillage d'emboutissage des figures 1 et 2 ;
• la figure 4 est une vue de l'outillage d'emboutissage de la figure 1 en position de fermeture ;
• la figure 5 est une vue de dessus du serre-flan de l'outillage d'emboutissage et dont la portée de serre-flan présente une surface de serrage homogène du flan ;
• la figure 6 est une vue semblable à celle de la figure 5 et représentant une zone de décalage de la portée du serre-flan n'assurant pas une homogénéité de serrage du flan ;
• la figure 7 est une vue en perspective du serre-flan conforme à l'invention ; et
• la figure 8 est une vue agrandie de la partie cerclée en VIII de la figure 7.

The invention will be better understood, and other objects, characteristics, details and advantages thereof will emerge more clearly in the explanatory description which follows given with reference to the accompanying drawings given only by way of example illustrating one embodiment. of the invention and in which:

• The figure 1 is an exploded perspective view of part of the stamping tool of the invention and occupying an open position before clamping a blank;
• the figure 2 is a schematic view showing a complementary part of the stamping tooling of the figure 1 ;
• the figure 3 is a partial sectional view of the lower part of the stamping tooling of figures 1 and 2 ;
• the figure 4 is a view of the stamping tools of the figure 1 in the closed position;
• the figure 5 is a top view of the blank holder of the stamping tool and of which the blank holder surface has a homogeneous clamping surface of the blank;
• the figure 6 is a view similar to that of the figure 5 and representing a zone of offset of the surface of the blank holder which does not ensure uniform tightening of the blank;
• the figure 7 is a perspective view of the blank holder according to the invention; and
• the figure 8 is an enlarged view of the part circled in VIII of the figure 7 .

Referring to the figures, reference numeral 1 denotes a press tool, more particularly a tool for stamping sheets, in particular relatively large metal blanks used in the automotive industry.

By way of example, the stamped part formed from the blank stamped by the stamping tool 1 may consist of a passenger compartment side or the roof of a motor vehicle.

The stamping tool 1 comprises a base or lower frame 2 fixed to the upper surface of a support table 3 (also called PMR or mobile rolling plate) belonging to the press and a die 5 fixed under the slide 17 also belonging to the press. The base or lower frame 2 consists of a punch 4 and a blank holder 8 is vertically movable above the base 2 as will be seen later.

The stamping tool 1 is further actuated by a hydraulic stamping cushion 7 belonging to the press housed and under the support table 3.

The blank holder 8 comprises a plurality of cylindrical vertical columns 9 extending below the blank holder 8 opposite the bearing surface 10 of the blank holder 8 intended to enclose with the bearing surface 11 of the die 5 the blank 6 during the stamping phase of this blank.

The vertical columns 9 of the blank holder 8, which pass through holes 14 of the base 2 and of the support table 3, comprise at their lower ends bobéchons 12, which are removably fixed to the lower ends of these columns by screwing.

The stamping tool 1 also comprises vertical stamping rods or candles 13 respectively passing through the vertical bores 14 and the lower ends of which bear on the stamping pad 7.

The vertical columns 9 of the blank holder 8 are supported by their bobechons 12 respectively on the upper ends of the vertical stamping rods 13.

The stamping tool 1 further comprises an upper frame 15 comprising two parallel uprights 16 resting on the table 3 and which comprise the slide 17 capable of moving vertically as symbolized by the double arrow F in figure 2 under the action of hydraulic cylinders 18, the slide 17 supporting the die 5. Thus, the die 5 can move vertically towards the blank holder 8. The latter is vertically guided relative to the base 2 by its sliding contact corners in the angled corners 2a of the base 2.

When the die 5 descends vertically under the action of the control jacks 18, the blank 6 is clamped between the bearing surfaces 10, 11 respectively of the blank holder 8 and of the die 5 and the blank holder 8 descends vertically into the base 2 with the vertical cylindrical columns 9, resting by their bobéchons 12 on the upper ends of the vertical stamping rods 13, respectively engaging in the holes 14 of the base 2 until the closed position of the stamping tool represented in figure 4 to stamp the blank 6 and make the desired stamped part.

During the vertical downward movement of the blank holder 8, the hydraulic cushion 7 exerts a vertical force upwards via the rods 13, the bobéchons 12 and the cylindrical columns 9 to exert the clamping force of the blank 6 by the span 10 of the hold-down 8.

The figure 5 represents the bearing surface 10 of the blank holder 8, the entire surface of which is homogeneous, that is to say it ensures a homogeneous clamping of the blank 6 between the bearing surface 10 and the bearing surface 11 of the die 5 to ensure good regulation of the sheet blank feed.

The figure 6 shows the situation where the seat 10 of the hold-down 8 is correct, that is to say homogeneous over a large part of its surface, but has a part of the surface offset relative to the correct seat as symbolized at 10a and which does not ensure a homogeneous clamping of the blank between the two surfaces 10 of the blank holder 8 and 11 of the die 5, that is to say that the bearing 10 of the blank holder 8 will not come into full contact with the blank under the staff 11 of the die 5.

To remedy this problem, the invention proposes to insert between the bobechons 12 and the lower ends of the cylindrical columns 9 of the blank holder 8, respectively, shims 19 for the cylindrical columns 9 located opposite the zone 10a. away from the remaining homogeneous surface of the seat 10 of the blank holder 8.

Thus, when the blank holder 8 descends vertically following the vertical downward movement of the die 5, the hydraulic cushion will exert on the cylindrical columns 9 of the blank holder 8 an upward vertical force deforming or elastically twisting the blank holder. 8 so that the bearing 10 thereof ensures tightening homogeneous blank 6 between the bearing surface 10 of the blank holder 8 and the bearing surface 11 of the die 5, thanks to the presence of the foils 19.

The foils 19 are in the present case in the form of rings clamped between the lower ends of the cylindrical columns 9 and the corresponding bobéchons 12 screwed into these ends.

The thicknesses of the foils 19 depend on the magnitude of the offset between the bearing surface 10a and the remaining homogeneous bearing surface 10 of the blank holder 8 depending on each hydraulic press used of the same model and of the same brand.

By way of example, the thickness of each foil 19 can vary between 1/10 mm to 1 mm depending on the presses used.

Of course, the blank holder 8 is made of a material allowing it to deform elastically so that it can be used on another press of the same type as the previous one.

The invention therefore consists in deforming the blank holder 8 by wedging the bobechons or spacers 12 with shims 19 so as to adapt the reach 10 of the blank holder to the production press and thus find an identical clamping to the press. focus. In this way, the grinding and honing operations carried out previously on the production presses are avoided.

The invention thus has the advantage of saving time for adaptation in a production press and does not require grinding or honing on the production line and, consequently, does not produce pollution linked to these grinding operations. and honing, resulting in better quality stampings.

In addition, the time spent on the manufacturing line is less important, consequently reducing the manufacturing costs.

Claims (4)

1. A tool for the stamping of a flan (6) for the formation of a stamped part, including a motor vehicle, including

   - a lower base (2)

   ∘ attached to a support table (3)

   ∘ and having a punch (4),

   ∘ a stamping cushion (7) under the support table (3),

   ∘ a flannel (8) located above the base (2) and having vertical columns (9) at the lower ends with bobbins (12) in support on the upper ends of vertical stamping stems (13) passing through bores (14) of the base (2) and of the support table (3), respectively, and the lower ends of which are in support of the cushion stamping (7),

   ∘ a slider (17)

   ▪ supporting a matrix (5) capable of moving vertically to the flanking wheel (8),

   ▪ the latter and the matrix (5) having two litters (10.11) between which the flan can be placed (6), the stamping rod (13) being capable of transmitting the tightening force of the stamping cushion (7) to the range (10) of the greenhouse (8),

   characterized in that the vertical columns (9) of the flannel (8) each have between its end and the corresponding coil (12) at least one flannel (19) allowing elastic deformation of the flannel (8) by the stamping cushion (7) and the stamping rod (13) to ensure a homogeneous tightening of the flan (6) over the full range of the greenhouse flan (8).
2. Pressing tool according to Claim 1, characterized that each coil (12) is removable fixed by screw at the end of the corresponding vertical column (9) of the greenhouse (8) and the clinker (19) can be clamped between the coil (12) and the end of the vertical column (9) of the greenhouse (8).
3. Packing tool according to Claim 1 or 2, characterized as the thickness of the flashing machine (19) is between 1/10 mm and 1 mm depending on the stamping tool used.
4. Pressing tool according to one of the claims 1 to 3, characterized as vertical columns (9) containing the flashers (19) are located opposite an area of the scope (10) of the flannel (8) having a difference of surface relative to the homogeneous remaining surface of the span (10).

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