EP0653255B1 - New rivet-like joining point of sheet metals by cold flowing and machine tool for realizing such a connecting point - Google Patents

Description

The present invention relates to a tool for making assembly points sheet metal blanks by cold flow according to the preamble of claim 1. Such an assembly is known in the industry as "clinching".

To assemble several sheet blanks, we use generally spot resistance welding. But this technique cannot be used when uses so-called coated sheets, i.e. sheets galvanized, lacquered or painted because the heat given off during welding destroys the coating.

To avoid the inconvenience of assembly by spot welding, we know the assembly by creep cold which consists of superimposing, at least, two blanks to keep them applied one against the other by blank clamps, to be stamped using a punch said blanks against a die in order to form in one of blanks a cavity whose side wall has, in the vicinity from the bottom, an enlargement, in the other blank being formed a cavity of corresponding shape marrying, by its external surface, the shape of the cavity of the first blank.

Thus, we realize a kind of "autorivet" which hooks the sheets together. This assembly is fully mechanical and despite stretching of the sheets at assembly points the coating layer is not damaged which prevents corrosion. Thanks to this technique have can assemble blanks of sheets having natures different, for example, blanks of steel sheets with blanks of aluminum sheets.

This technique also presents, compared to spot resistance welding, very many advantages.

The investment is less expensive.

The power required is less important.

The process is not polluting.

Avoid electrical noise emissions that disrupt digital controls and computers.

Easier and simpler settings.

The prior art knows the English patent n ° 2 189 175, which describes a tool according to the preamble of claim 1, as well as U.S. Patent No. 5,031,442.

In U.S. Patent No. 5,031,442, it is provided a lower tool with a guide surface for two half-shells which have a cooperating convex surface with the guide surface. At the time of training from the assembly point, the half-shells tip over the guide surface.

Such an arrangement has many drawbacks. The sheets are no longer held between two flat surfaces. If a half-shell tips over the other, the assembly point has a defect and we is necessarily limited in the thickness of the sheets.

British Patent No. 2,189,175 describes a provision close to that of American patent n ° 5 031 442 but in which the shells have a tilting radius more important than in the previous case so that the sheets are better held at their bottom surface, however, as in the embodiment described in the English patent, considering that there is always filings cutting during the assembly point formation, you cannot be assured that the tipping of the shells will be uniform.

One of the aims of the present invention is to remedy these drawbacks.

According to the invention, this goal is achieved by a tool for the realization of assembly points for sheet metal blanks by cold creep consisting in practicing, simultaneously, in two blanks of sheet metal using a punch and a die a cavity circular, the cavities being housed one inside the other and having, in the vicinity of the bottom, an enlargement, said tool being of the type comprising a punch, a blank clamps and a bottom tool with an anvil and supporting a matrix formed of at least two shells complementary mobile on a tool guide surface inferior against the action of means tending to bring them together, stops being provided to limit their spacing, Shells complementary being slidably mounted on the surface of guidance in two opposite and arranged directions in a cage secured to the lower tool, characterized in that said cage is breakthrough guide holes for guide pins integral with said shells and sliding in said guide holes.

Thanks to this arrangement, the matrix does not present no articulation which generally constitutes a weakening. The position of the stops determines the stroke shells according to the thickness of the sheet blanks and we can look like sheet blanks with thicknesses on the order of 3mm.

According to yet another preferred characteristic, the means tending to bring the shells together are formed by compressed air jets directed against the external surface said shells.

According to a preferred embodiment variant, it is possible to provide detection means to verify that the displacement shells, during point formation assembly, corresponds to a determined setting.

Figure 1 montre en élévation, schématiquement, une machine à assembler des tôles par fluage à froid.

Figure 2 est une vue partielle de la machine de la figure 1 montrant le dégagement de la matrice.

Figure 3 est une vue en coupe suivant la ligne 3-3 de la figure 1.

Figure 4 montre en élévation schématiquement une variante de la machine à assembler de la figure 1.

Figure 5 est une vue en perspective éclatée montrant une forme de réalisation d'une matrice.

Figure 6 est une vue en coupe axiale montrant le poinçon et la matrice en position d'attente.

Figure 7 est une vue en plan de la matrice.

Figure 8 montre en coupe axiale, le poinçon et la matrice lors de l'assemblage des flans de tôle.

Figure 9 montre en plan la matrice lors du fluage.

Figure 10 montre en coupe un point d'assemblage réalisé.

Figure 11 montre en plan le point d'assemblage de la figure 10.

Figure 12 montre schématiquement le système de nettoyage de la matrice.

Figure 13 et figure 14 sont des vues similaires aux figures 7 et 9 montrant une variante de réalisation de la matrice.

Figure 15 montre en coupe un outil inférieur suivant encore un autre mode de réalisation.

Figure 16 montre en coupe un point d'assemblage réalisé avec l'outil de la figure 15.

Figure 17 est une vue en plan du point d'assemblage de la figure 16.

Figure 18 montre en coupe axiale une matrice suivant encore une variante de réalisation.

Figure 19 est une vue en plan correspondant à la figure 18.

Figure 20 montre en coupe axiale une matrice suivant un autre mode de réalisation.

Figure 21 montre en perspective une variante de réalisation de la matrice.

Figure 22 est une vue en coupe montrant un point d'assemblage réalisé avec la matrice de la figure 21.

The invention will now be described in more detail with reference to particular embodiments given by way of example only and shown in the accompanying drawings, in which:

Figure 1 shows in elevation, schematically, a machine for assembling sheets by cold creep.

Figure 2 is a partial view of the machine of Figure 1 showing the release of the matrix.

Figure 3 is a sectional view along line 3-3 of Figure 1.

Figure 4 shows in schematic elevation a variant of the assembly machine of Figure 1.

Figure 5 is an exploded perspective view showing an embodiment of a matrix.

Figure 6 is an axial sectional view showing the punch and the die in the standby position.

Figure 7 is a plan view of the matrix.

Figure 8 shows in axial section, the punch and the die when assembling the sheet blanks.

Figure 9 shows in plan the matrix during creep.

Figure 10 shows in section an assembly point made.

Figure 11 shows in plan the assembly point of figure 10.

Figure 12 shows schematically the matrix cleaning system.

Figure 13 and Figure 14 are views similar to Figures 7 and 9 showing an alternative embodiment of the matrix.

Figure 15 shows in section a lower tool according to yet another embodiment.

Figure 16 shows in section an assembly point made with the tool of Figure 15.

Figure 17 is a plan view of the assembly point of Figure 16.

Figure 18 shows in axial section a matrix according to another variant embodiment.

Figure 19 is a plan view corresponding to Figure 18.

Figure 20 shows in axial section a matrix according to another embodiment.

Figure 21 shows in perspective an alternative embodiment of the matrix.

Figure 22 is a sectional view showing an assembly point made with the matrix of Figure 21.

In Figure 1, there is shown a machine 1 which includes, at its lower part, a support 2 for a matrix 3, while at its top it is provided with a jack 4 supporting a punch 5 intended to cooperate with matrix 3.

Sheet blanks 7 and 8 are inserted between the punch 5 and the die 3, a blank holder 6 being provided to block said sheets.

The support 2 is carried by an arm 10 mounted sliding on an axis 11 against the action of a spring compression 12.

The arm 10 has an inclined ramp 14 and a support surface 15.

In the body of the machine is mounted sliding a rod 17 whose end is secured to a yoke 19 supporting an axis on which a caster rotates 18.

As seen in Figure 3, the surface support 15 is on the wheel 18 and on the two wings of clevis 19.

The rod 17 can be connected to a means of command so that it can occupy a first position in which the caster 18 cooperates with the bearing surface 15 and corresponding to the creation of an assembly point blanks (see Figure 1) and a second position (see Figure 2) in which the wheel 18 is deleted so that the matrix 3 is discarded to release the blanks 7 and 8 after completion of the assembly point.

In Figure 4 there is shown a machine for Figure 1. In this figure, the references have been transferred used in Figures 1 and 2 to designate the organs corresponding but assigned the letter "a".

The machine shown in Figure 4 provides a support 2a for a matrix 3a, a jack 4a supporting a punch 5a intended to cooperate with the matrix 3a.

The sheet blanks 7'a and 8'a are inserted between the punch 5a and the matrix 3a and maintained during the creep by a blank holder 6a.

In the body of the machine is mounted a rod 17a, the free end of which is integral with the support 2a. There is provided a shoe 110 intended to serve as a support for support 2a.

When making an assembly point, the support 2a is arranged as shown in FIG. 4. After the assembly point has been made, the rod 17a is controlled in the direction of the arrow f so that the assembly point, thus obtained, can be released.

Figures 5 to 9 show an embodiment of matrix 3 or 3a.

This matrix 3 or 3a consists of four shells 20, 21, 22 and 23 which rest on their underside on a guide surface 25 of a lower tool 26.

The guide surface 25 and the underside shells 20 to 23 are perfectly erected so that said shells can slide freely on said surface 25.

The lower tool 26 has an anvil 28 with an imprint 27 extending over a diameter of said anvil and affecting the shape of a bar with edges rounded.

Each shell has, in the vicinity of its lower edge, a tapped hole 30 into which is screwed a guide pin 31 and, near its edge upper, a throat 32.

The shells 20 to 23 are assembled by a toroidal tension spring 33 inserted in the grooves 32, said shells being housed in a cage 34 pierced 35 holes in which can slide freely nipples 31.

The cage 34 may include a connector 37 connected to a compressed air source, to send compressed air to prevent small filings that form during of the assembly point interfere with proper operation of the matrix, the small filings being thus ejected.

The cage 34 extends in order to encompass part from the edge of the lower tool adjacent to the guide surface 25, said cage being fixed by screws 38 which are screwed into threads 39 and passing through holes 40 of said cage.

As seen in Figures 6 to 9, the blanks are inserted between the punch 5 and the die 3 then, the punch 5 is lowered so that the blank holder 6 blocks the blanks 7 and 8, the punch 5 deforming by stamping cold said blanks to form this assembly point.

Figures 10 and 11 show the point assembly obtained. When engaging punch 5, cylindrical cavities 7a and 8a are formed in the sheets and in the bottom of the cavities of projections 7b and 8b corresponding to the imprint 27 of the anvil 28. As the shells 20 to 23 which form the matrix 3 are maintained assembled by a spring 33 when the sheet metal blanks 7 and 8 are pinched between the drawing tool 26 and the punch 5, the shells 20 to 23 move apart elastically so that it forms, by creep, at the near the bottom, cavities 7a and 8a, enlargements 7c and 8c ensuring an intimate connection between the blanks 7 and 8. The projections 7b and 8b of the assembly point oppose any rotation of one of the blanks 7 or 8 relative to the other.

There is an automatic system to send lightly oiled compressed air in cage 34 between the shells 20 to 23.

When the cylinder 4, which controls the movement of punch 5 reaches the active end of travel through a proximity sensor 42, it controls the sending system compressed air.

The system is shown in Figure 12 and includes a pump 43, a drawer 44, a balloon 45 inserted on a pipe 46 with interposition of a valve non-return 47, the ball 45 being connected by a pipe 49 at the end piece 37 of the cage 34. On the pipe 49 being interposed two valves 48 whose opening is controlled when the jack 4 reaches the active end of travel, so that the compressed air stored in the balloon 45 is sent into the cage 34 through the shells 20 to 23 which are separated from each other (see Figure 7) which of course facilitates the evacuation of small filings, sending compressed air sliding during the spacing of the cylinder 4 and until the point assembly is released from the matrix 3.

When the compressed air supply is stopped, the drawer 44 is moved so that the pump 43 fills, again, with compressed air balloon 45.

In Figures 13 and 14, there is shown a alternative embodiment of the matrix 3 or 3a. In these figures, the references used in the figures are reported to designate the corresponding elements, but affected by the letter "a". As seen in these figures 13 and 14, the cage 34a has stops which can be formed by screws and which limit and to adjust the spacing of the shells 20a to 23a between them.

The lower tool (see Figure 15) can present a cruciform imprint on its anvil 102 103, the punch having a corresponding imprint.

In this case, an assembly point is made such as that shown in Figures 16 and 17.

We can, in this case, provide in the lower tool an axial duct 105 which, by branches 106, emerges between the branches of the footprint of the anvil and which is connected by a suitable pipe to the system compressed air control device shown in figure 12.

The assembly point of Figures 16 and 17 includes, from the two sheet blanks 7h and 8h, a cavity 7i inserted into cavity 8i with enlargements 7d and 8d in the vicinity of the bottom, the latter presenting a 8k and 7k cross boss.

In the various figures, a matrix formed of four shells, but one could, well heard, realize the matrix with only two shells or three.

In Figures 18 and 19, a variant embodiment of the matrix which is designated here by the general reference 111.

This matrix includes four shells 112, 113, 114 and 115 which rest by their lower face on a guide surface 116 of a lower tool 117.

The guide surface 116 and the underside shells 112 to 115 are machined so that said shells can slide very freely.

The shells 112 to 115 have a groove 118 in which a toroidal tension spring is inserted 119 which tends to apply the shells 112 and 115 against the lateral surface of the tool 117.

Each shell 112 to 115 is integral with a guide pin 120 which can slide in a bore smooth 121 of a cage 122 integral with the tool 117.

The cage 122 has four housings 124 which pass through bores 121 and receive detectors proximity 125 connected to a comparator 126 in which has been entered in a corresponding parameter memory at a necessary stroke of the shells so that the point assembly is correct.

So, if one of the detectors perceives an anomaly, a signal can be issued and so we can immediately adjust or repair if found necessary.

FIG. 20 again shows an alternative embodiment of the matrix. This matrix is designated in its together by reference 130 and includes a tool 131 with a guide surface 132 for shells 133, on the tool 131 being fixed a cage 134 pierced with bores 135 in which are guided pins 136 integral with the shells.

Tool 131 has an axial channel 137 opening into side channels 138 connected to channels 139 opening onto the guide surface 132 opposite the rear face of the shells 133.

The axial channel 137 is intended to be connected to a source of compressed air and the jets that open out channels 139 are oriented and powerful enough that the shells 133 are kept applied against a tail 140 of the tool, the upper end of which constitutes a anvil 141 which has a corresponding imprint.

As in the previous embodiments, when the sheet blanks are pinched between the tool stamping and the punch, the shells 133 move apart against the action of compressed air jets to allow creep to form the assembly point.

Figure 21 is an alternative embodiment of the lower tool. In this embodiment, the tool lower which is designated by the general reference 150 has a guide surface 151 on which shells such as shells 20 to 23 can slide against the action of a spring 33.

The free end of the lower tool ends by an anvil 152 comprising an imprint 153.

The part of the tool 150 extending from the guide surface 151 at the anvil 152 has a first cylindrical part 155 having a smaller large diameter, these two parts being connected by a shoulder 157.

Figure 22 shows an assembly point formed in two 7m and 8m sheet blanks, the punch allows to obtain 7n and 8n cavities with enlargements near the bottom 7p and 8p, said bottom comprising bosses 7o and 8o corresponding to the imprint 153.

As at the time of point formation, the material is pushed back between the inner side surface shells and part 156 it's sort of formed bead 81.

Such an arrangement makes it possible in particular to obtain an assembly point with parts having thicknesses different.

Of course, the invention is not limited to the embodiments which have just been described and represented. We can bring many changes in detail without departing from the framework of the invention as defined in the claims.

Claims (4)

1. A tool for making connecting points for sheet metal blanks by cold flowing consisting in making simultaneously in two sheet metal blanks (7, 8, 7a, 8a, 7b, 8b, 7m, 8m), by means of a punch and a die, a circular cavity (7a, 8a, 7i, 8i, 7n, 8n), the cavities (7a, 8a, 7i, 8i, 7n, 8n) being housed in one another and having, in the vicinity of the base, an enlargement (7c, 8c, 7j, 8j, 7p, 8p), the said tool being of the type comprising a punch (5, 5a), a holding-down device (6, 6g) and a lower tool (26, 117, 131, 150) having an anvil (28, 102, 141, 152) and supporting a die (3, 32, 111, 130) formed of at least two complementary shells (20, 23, 20a, 23a, 112, 115, 133) moveable on a guide surface (25, 116, 132, 151) of the lower tool (26, 117, 131, 150) against the action of means (33, 119, 137, 139) tending to bring them closer together, stops being provided to limit their spacing, the complementary shells (20, 23, 20a, 23a, 112, 115, 133) being mounted sliding on the guide surface (25, 116, 132, 151) in two opposite directions and disposed in a cage (34, 34a, 122, 134) integral with the lower tool (26, 117, 131, 150),
   characterised in that the said cage (34, 34a, 122, 134) is pierced by guide holes (35, 135) for guide studs (31, 31a, 120, 136) integral with the said shells (20, 23, 20a, 23a, 112, 115, 133) and sliding in the said guide holes (35, 135).
2. A tool for making connecting points, according to Claim 1,
   characterised in that it comprises four shells (20, 21, 22, 23; 21a, 22a, 23a; 112, 113, 114, 115), with two opposite shells sliding in two opposite directions, whereas the two other opposite shells slide in opposite directions perpendicular to those of the first opposite shells.
3. A tool for making connecting points according to Claim 1,
   characterised in that the means tending to bring the shells (133) closer together are formed by jets of compressed air directed against the outer surface of the said shells (133).
4. A tool for making connecting points according to Claim 1,
   characterised in that it comprises detection means (125, 126) to verify that the displacement of the shells (20, 23; 20a, 23a; 112, 115, 133) during the formation of the connecting point corresponds to a predetermined setting.

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