EP3253510B1 - Facility for the hot-forming of metal material - Google Patents

Description

The present invention relates to a hot forming plant of flat metal material to be able to form metal parts.

This type of installation includes a tool driven by a press. The areas of application envisaged include, but are not limited to, reworking parts, or transfer, or "tools to follow".

The presses are equipped with at least two supports driven alternately in translation towards one another, and a tool comprising a die installed on one of the two supports, and on the opposite side, a punch mounted on the other support. The tool is equipped with heating means, for example a heating fluid circuit or even heating cartridges.

In order to form metal parts, for example for part reworkings, the parts to be picked up sequentially between the punch and the die, and when the two supports are driven towards each other, the punch enters the die. by dragging the piece to form and / or cut it. The matrix then defines the outer contours of the part, while the punch defines the internal contours.

For these tools, and particularly the "tool to be followed", which can be actuated, between 40 and 100 times per minute, for example, it is necessary to fix the punch and the die respectively on the two supports very precisely and extremely rigid. Usually, the die and the punch have at the periphery of their fingerprints, axial holes for receiving screws engaging in the supports of the tool.

However, given the thermal expansions experienced by the tool, it can be observed, a significant loosening of the screws, a relative displacement of the die and the punch, or even breakages of screws. This then poses problems of tool life or, at the very least, insufficient precision of the manufactured part.

Also, a problem that arises and that aims to solve the present invention is to provide an installation that allows to overcome the impact of thermal variations on the assembly of different parts of the tool.

The document DE 10 2009 018797 A1 discloses a hot forming plant according to the preamble of claim 1.

For this purpose, the present invention proposes a hot forming plant for a flat metallic material comprising, on the one hand, two supports intended to be driven alternately in translation towards each other, and a tool intended to be heated comprising at least one die element and at least one punch element, said tool being thermally deformable, and secondly fixing members for holding said at least one die element on one of said supports in said fixed position and said minus one punch member on the other of said support, so that said at least one punch member cooperates with said at least one die member as said carriers are driven toward each other. Said fixing members comprise elastically deformable tabs; and said tabs deform elastically when said tool is heated.

Thus, a feature of the invention lies in the implementation of elastically deformable tabs for maintaining in a fixed position the matrix and the punch respectively on their support while allowing the thermal expansion of this punch and this matrix when they are heated. Indeed, the tool as a whole, and more specifically the punch and the die, which are made of steel, expand when they are heated. And they are heated during forming operations to facilitate the deformation of the flat metal material. The punch and the matrix, made of steel, are carried for example at a temperature of 200 ° C., and as a first approximation, their dimensional variation ΔL is equal to β. L. ΔT, where L is the length and ΔT, the temperature variation. The coefficient β is its function of the characteristics of the material of the tool. Also, for a steel tool part with a length of 150 mm, the coefficient β is for example: 18, and then a variation of 0.5 mm is observed when it is brought from room temperature, up to at a value of 200 ° C. Therefore, thanks to the elastically deformable tabs, the tool can be deformed, and more precisely the die and the punch, while remaining in a fixed position on the supports. Consequently, despite the dimensional variations of the tool, the assembly is not over constrained with the risk of breakage related thereto, and the accuracy of the stamping of the part remains.

According to a particularly advantageous embodiment of the invention, said at least one die element and / or said at least one punch element each have a rear bearing surface and opposite retaining edges, and moreover said tabs each have an anchor end anchored to the support and a return retaining end engaging said retainer edges. In this way, thanks to the opposite retaining borders, which extend laterally behind the fingerprints, the retaining end of the tabs can come to support to secure said at least one forming element matrix and / or said at least a punch element. As will be explained hereinafter, the opposite retaining borders extend, for example two by two parallel on either side of the die member and / or the punch member, and at least one pair of tabs is implemented to engage respectively on the two borders. Thus, when said at least one die element and / or said at least one punch element expand in a direction substantially parallel to that of the reciprocating movement of the two supports, the two legs of the pair of legs deform elastically and substantially separate from each other while rigidly holding the two elements of the tool.

The forming plant further comprises, particularly advantageously, isolation shims mounted between said at least one die element and / or said at least one punch element, and said corresponding supports. In this way, the dissipation of the thermal energy provided to the tool to facilitate forming, is less and therefore the installation generally requires less energy and therefore its use is less expensive. As will be explained in more detail in the following description, the reduction of thermal bridges between the tool and the supports, thanks to the elastically deformable tabs, also allows energy gain.

Preferably, said retaining end back is equipped with a screwable clamping member adapted to bear against said retaining edges. In this way, after the tool has been positioned on the supports, the retaining ends of the tabs opposite the retaining edges, the implementation of the screwable clamping members provides a force support against the die member and / or the punch element to their respective support.

According to an alternative embodiment, said anchoring end of said lugs extends back substantially symmetrically with respect to said retaining end. Thus, the tab is formed at C, and the anchoring end of the tabs is adapted to be secured to the support, opposite to said retaining end in the same way. In this way, the tab formed in C comes to grip a border of the die element and / or the punch element and a part of the corresponding support.

Also, each of said supports preferably has a bearing surface substantially perpendicular to the alternative translation direction of said two supports, and two lateral shoulders opposite to said support face. The anchoring ends in return of the lug respectively engage the two opposite lateral shoulders having bearing surfaces. Advantageously, the bearing surfaces extend obliquely so as to be able to clamp the die element and / or the punch member against their corresponding support by laterally driving the leg formed in C. It will be explained more in detail in the following description this ramp mechanism for clamping.

In addition, said tool further comprises a blank holder, so as to maintain the flat metal material when the punch comes to cooperate with the matrix to come deform.

• la Figure 1A est une vue schématique partielle en perspective d'une installation de formage à chaud selon un premier mode de mise en oeuvre ;
• la Figure 1B est une vue schématique partielle en coupe droite de l'installation représentée sur la figure 1A ;
• la Figure 2A est une vue schématique partielle en coupe droite d'une installation de formage à chaud selon un second mode de mise en oeuvre ; et,
• la Figure 2B est une vue schématique de détail de la figure 2A.

Other features and advantages of the invention will emerge on reading the following description of particular embodiments of the invention, given by way of non-limiting indication, with reference to the appended drawings in which:

• the Figure 1A is a partial schematic perspective view of a hot forming plant according to a first embodiment;
• the Figure 1B is a partial schematic view in cross-section of the installation shown on the Figure 1A ;
• the Figure 2A is a partial schematic cross-sectional view of a hot-forming plant according to a second mode of implementation; and,
• the Figure 2B is a schematic view of detail of the Figure 2A .

The Figure 1A shows in perspective and partially a hot forming installation 10 of the "tool to follow" type. The installation 10 comprises two opposite supports, an upper support 12 and a lower support 14 on which are respectively mounted a punch 16 and a matrix 18. The upper support 12 is intended to be driven in translation towards the lower support 14 in an alternative manner and at a relatively high frequency, for example 60 times per minute. Accordingly, the punch 16 is driven in motion between a position spaced apart from the matrix 18, as shown in FIG. Figure 1A , and a position where it cooperates with the matrix 18 to form a strip of a metallic material 20. The strip of metallic material 20 is sequentially driven in steps between the punch 16 and the matrix 18 in a direction substantially perpendicular to the direction vertical movement of the punch 16.

The punch 16 and the die 18 are intended to be brought to temperature, for example at a temperature between 160 ° C and 200 ° C so as to make it easier to form the metal material 20 strip. To do this, the punch 16 comprises upper heating cartridges 22, while the matrix 18 comprises lower heating cartridges 24. These heating cartridges 22, 24 are electrical resistors for heating the punch 16 and the die 18, respectively.

The punch 16 is thermally insulated from the upper support 12 via an upper insulator 26 while the matrix 18 is thermally insulated from the lower support 14 via a lower insulator 28. The insulating elements are for example made in incompressible ceramic materials.

The punch 16 is then secured to the upper support 12 by means of two upper fixing tabs 29, 30 symmetrical to each other, while the matrix 18 is held integral with the lower support 14 via two lower fixing lugs 32, 34 symmetrical to each other also. The fastening tabs C, upper 30 and lower 34 will be described in more detail with reference to FIG. Figure 1B . This last figure illustrates laterally one of the two sides of the tool including the punch 16 and the die 18, and is symmetrical to the other side.

We find on the Figure 1B the upper support 12 opposite the lower support 14 and the punch 16 and the matrix 18 of which they are respectively integral. Between the punch 16 and the upper support 12 is inserted the upper insulation 26, while between the matrix 18 and the lower support 14 is inserted the lower insulation 28.

The upper support 12 has an upper front support surface 35, while the punch 16 has a rear upper support surface 36 opposed to an upper work surface 38 and upper lateral retention edges 40. The attachment tabs upper 30 have an upper anchoring end 42 held in a fixed position by screwing into the sidewall 44 of the upper support 12. They also have an upper retaining end 46 coming to extend facing the upper lateral retaining edges 40. The upper fastening tabs 30 then overlap the upper edge of the insulation 26. The upper back retention end 46 is equipped with an upper screwable clamping member 48 intended to bear against the lateral edges 40 so as to to compress it against the upper support 12 by sandwiching the upper insulation 26. It will be observed that the choice of thermal insulation goes to an incompressible rigid material. For example, a ceramic material will be used. In this way, and since the two upper fixing lugs 30 are installed on each side, the punch 16 is held in a fixed position relative to the upper support 12.

In the same way, the matrix 18 is made integral with the lower support 14. Thus, it has a lower rear bearing surface 50 opposite a lower working surface 52 and lower lateral retaining edges 54. In addition, the lower support 14 has a lower front support surface 56 and two lower opposed lateral shoulders 58 forming lower bearing surfaces.

With respect to the lower fastening tabs 34, they have a bottom anchoring end 60 engaging on the two opposite lateral shoulders 58, and a lower holding end 60 The lower fastening tabs 34 also overlap with the lower side retaining edges 54. The lower fastening tabs 34 also overlap the lower insulating portion 28. Also, the lower retaining end 62 is provided with an lower clamping member 64 being pressed against the lower lateral retaining edges 54 by means of an insulating strip 66. It will be observed that the free contact end of the screwable tightening members 64 has a substantially hemispherical shape. Thus, in the manner of a clamp, the lower fastening tabs 34 secure the matrix 18 and the lower support 14 while sandwiching the lower insulation 28. Thanks to the insulating strip 66 on the one hand, and the one-off support of the free contact end of the lower screw-fastening members 64, on the other hand, very little thermal energy of the matrix 18 is dissipated by conduction.

Thus, thanks to the fastening tabs, both upper 29, 30 and lower, 32, 34, which are formed in C and are elastically deformable, the dimensional variations of the punch 16, and / or the die 18, due to thermal variations. of these, are absorbed. Indeed, the fixing lugs 29, 30, 32, 34 are deformed substantially in order to be able to absorb these dimensional variations while maintaining the pressure they exert on the punch 16 and the die 18 to maintain them in a fixed position relative to the support 12, 14.

In addition, thanks to the thermal insulators 26, 28, 66, the thermal bridges are limited between the punch 16 and the die 18 and the supports, upper 12 and lower 14. Therefore, the tool is easily maintained at the set temperature .

We will now refer to the Figure 2A representing a hot forming plant 10 'according to another embodiment. The elements illustrated on this Figure 2A having the same functions as those shown on the Figures 1A and 1B , will present the same reference assigned a prime sign: "'", while the new elements will be referenced in the continuity of the sequence of references already affected.

According to this other embodiment, a metal coin recovery forming installation 20 ', on the one hand the die and the punch are inverted; the punch 16 'being integral with a lower support 14', while the matrix 18 ', consisting of two lateral parts, a left 70, a straight line 72 and a bottom 74, is secured to an upper support 12'; and on the other hand, the bearing spans are oblique as will be explained below in more detail.

It will be observed that the direction of travel of the metal parts 20 'is perpendicular to the plane of the Figure 2A . Also, the two lateral parts 70, 72 are respectively connected to the upper support 12 'by means of two pairs 71, 73, fastening lugs held spaced from each other by the bottom 74 of the matrix 18' .

First, we will explain with reference to the Figure 2B more specifically, the operating mode of the fasteners of one, straight 72, said two side portions of the die 18 'on the upper support 12'.

Thus, we find on this Figure 2B the right lateral part 72 of the matrix 18 'secured to the upper support 12' by means of two upper free attachment tabs 29 ', 30'. In addition, the right side portion 72 is equipped with heating cartridges 24 '. In addition, the hot forming installation 10 'comprises a blank holder 75 for holding the piece 20' in support when it is deformed.

The upper support 12 'has an upper front support surface 35', and two opposite upper lateral shoulders resulting from two opposite parallel grooves formed in the upper support 12 '. Thus, the two opposite opposite lateral shoulders form upper bearing surfaces 76. It will be observed that these upper bearing surfaces 76 are oblique with respect to the perpendicular of the alternative translation direction of the upper support 12 ', in that the shoulders are respectively inclined flaring outwardly of the groove that gives them birth. This inclination also makes it possible to maintain the assembly in the case of thermal expansion perpendicular to the direction of translation.

The lateral portion 72 of the matrix 18 'has two opposite straight grooves, also perpendicular to the alternative translation direction of the upper support 12', and defining respectively two edges of The lateral portion 72 of the die 18 'also has a rear bearing face 50'.

As for the upper free fastening tabs 29 ', 30', they each have an upper anchoring end in return 42 ', defining a complementary upper bearing surface 80 adapted to be applied against the upper bearing surfaces 76. And in contrast, the upper free fastening tabs 29 ', 30', each have a top retaining end 46 'provided with a support pin 82. It will be observed that the upper bearing spans complementary 80 are substantially inclined relative to a perpendicular to the mean plane of each of the fixing lugs. This inclination also makes it possible to maintain the assembly in the case of thermal expansion perpendicular to the direction of translation.

Thus, an upper insulating member 26 'is engaged between the upper front bearing surface 35' of the upper support 12 'and the rear bearing face 50' of the side portion 72 of the die 18 ', while on each side, the upper free fastening tabs 29 ', 30' are applied so that the complementary upper support bearing surfaces 80 bear on the upper support bearing surfaces 76 and that the bearing pins 82 abut against the opposite upper retaining edges 78. Thus, thanks to the bearing pins 82 and the upper insulation 26 'considerably reduces the dissipation of the thermal energy generated in the heart of the lateral portion 72.

In this way, it is understood that by forcing the two upper free fastening tabs 29 ', 30' parallel to each other, towards each other, the complementary upper bearing surfaces 80 respectively form ramp on the seats upper support 76, and consequently, the rear support surface 50 'compresses even more the upper insulating member 26' against the upper front bearing surface 35 '. In doing so, the side portion 72 of the die 18 'is rigidly bonded to the upper support 12'.

We will refer again to the Figure 2A . It will be observed that the left lateral portion 70 of the matrix 18 'is completely symmetrical with the right lateral portion 72 described with reference to FIG. Figure 2B , in relation to a median plane PM. Also, the left side 70 includes the same elements presenting the same functions. The two pairs 71, 73 of fastening lugs are thus kept spaced apart from each other by the bottom 74 of the matrix 18 'and they are clamped between two lateral brackets 84, 86. In this way, thanks to at these two lateral brackets 84, 86, the two pairs 71, 73 of the upper free fastening tabs 29 ', 30' are force-driven towards each other in order to rigidly connect the left lateral parts, respectively. 70 and 72 of the matrix 18 'to the upper support 12'.

In addition, it will be observed that the punch 16 'is connected to the lower support 14' according to the same mode of attachment.

With this method of fixing the matrix 18 'and the punch 16', their thermal expansion is made possible without compromising their attachment to the respective supports 12 ', 14' and therefore without altering their relative position to the wire deformations of the metal parts 20 '.

Claims (8)

1. An utility (10 ; 10') for hot forming a flat metallic material (20 ; 20') comprising, on the one hand, two supports (12, 14 ; 12', 14') intended to be alternately driven in movement the one towards the other, and a tool intended to be heated, comprising at least one matrix element (18 ; 18') and at least one stamp element (16 ; 16'), said tool being thermally deformable, and on the other hand, securing members (29, 30, 32, 34 ; 29', 30') allowing to maintain in a fixed position said at least one matrix element (18 ; 18') on one of said supports (12, 14 ; 12', 14') and said at least one stamp element (16 ; 16') on the other of said supports (12, 14 ; 12', 14'), so that said at least one stamp element (16 ; 16') cooperates with said at least one matrix element (18 ; 18') when said supports (12, 14 ; 12', 14') are driven the one towards the other ;
   characterized in that said securing members (29, 30, 32, 34 ; 29', 30') comprise elastically deformable legs ;
   and in that said legs are elastically deformed when said tool (16, 18 ; 16', 18') is heated.
2. The forming utility according to claim 1, characterized in that said at least one matrix element (18 ; 18') and/or said at least one stamp element (16 ; 16') have each one a back bearing surface (36, 50 ; 50') and opposite retaining edges (40, 54 ; 78), and in that said legs (29, 30, 32, 34 ; 29', 30') have each one an anchoring end (42, 60 ; 42') anchored on the support (12, 14 ; 12') and a back retaining end (46, 62 ; 46') engaged against said retaining edges (40, 54 ; 78).
3. The forming utility according to claim 2, characterized in that it further comprises insulation plates (26, 28 ; 26') mounted between said at least one matrix element (18 ; 18') and/or said at least one stamp element (16 ; 16'), and said corresponding supports (12, 14 ; 12').
4. The forming utility according to claim 2 or 3, characterized in that said back retaining end (46, 62) is equipped with a screwable clamping member (48, 64) ready to bear against said retaining edges.
5. The forming utility according to any of claims 2 to 4, characterized in that said anchoring end (60 ; 42') of said legs (32, 34 ; 30') extends backwards in a substantially symmetrical manner with respect to said retaining end (62 ; 46').
6. The forming utility according to any of claims 1 to 5, characterized in that each one of said supports (12, 14 ; 12', 14') is provided with a bearing face (56 ; 35') substantially perpendicular to the alternately movement direction of said two supports, and two side shoulders (58 ; 76) opposite to said bearing face making bearing spans.
7. The forming utility according to claim 6, characterized in that said bearing spans (58 ; 76) extend in an oblique way.
8. The forming utility according to any of claims 1 to 7, characterized in that said tool (16, 18 ; 16', 18') further comprises a blank holder (75).

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