FR2692181A1 - New connection point for cold drawing sheets - comprises a protrusion and recess in the sheets to be connected which interlock to form the connection - Google Patents

Abstract

A new connection point for use with sheets during cold drawing of the type in which one cuts simultaneously into at least two superimposed sheets (23,24) with the aid of a punch and a die, two embossments in a manner that form, in each of the sheets on one face, a cavity and on the other face a protrusion, the protrusion on the first sheet (23) being inserted in the cavity (27) of the second sheet (24). The cavity of the second sheet presents, in the neighbourhood. of its bottom, an expansion whilst the protrusion of the first sheet incorporates a splay lodging in the expansion in the second sheet. The cavity in the first sheet presents a series of folds extending essentially parallel from the bottom of the cavity towards the free edge. The tooling used to produce this new connection point in sheet metals is also claimed. USE/ADVANTAGE - The connecton points are used in the assembly of sheet metal, notably thin aluminium sheet by cold drawing. The formation of folds at the connection point increases the local thickness thus reinforcing the point of connection enabling the technique to be used for thinner sheet than is possible with conventional connections.

Description

The present invention relates to the realization

  sation of a plate assembly point, more particularly

  thick aluminum sheets by cold creep.

  The invention relates to the assembly by cold creep which consists in superimposing at least two sheets,

  keep them pressed against each other by a clamp

  blanks, to form a stamped part using a punch against a die in order to form in a first sheet a cavity whose lateral walls have, in the vicinity of the bottom, an enlargement, and in the second sheet a correspondingly shaped cavity , marrying by its external surface the

  shape of the cavity of the first sheet.

  In the technical language to use a

  such assembly, the term "clinching" is used.

  When making the stamping, the thick-

  the second sheet metal to the right of the side wall of the cavity is reduced due to the stretch produced by

  sinking the punch, this creates a slight weak-

  especially sensitive to the assembly point when using

  relatively thin aluminum sheets.

  One of the aims of the present invention is to

remedy this drawback.

  The assembly point, according to the invention, is of the type in which one practices simultaneously in at least

  two sheets superimposed using a punch and a die

  this two stamped so as to form in each of the sheets from one side, a cavity and on the other side a projection, the projection of the first sheet being inserted in

  the cavity of the second sheet, said cavity of said section

  sheet metal with, in the vicinity of its bottom, a widening

  sliding, while the projection of the first sheet comprises

  carries a flare housed in said widening, said point being characterized in that the cavity of the first

  sheet has a series of beads extending substantially-

  lying parallel from the bottom of said cavity towards

the free edge of it.

  Thanks to this arrangement, the assembly point is reinforced. Preferably, the beads are one in number

  of four and evenly spaced.

  The invention also relates to tools for producing the new assembly point as defined above and of the type comprising a punch with a blank holder, a matrix comprising an anvil against which are

  elastically applied movable shells on an over-

  guide face and limited in their movement by a

  stop, said tools being characterized in that the punch

çon has grooves.

  In order to facilitate the stripping of the punch after the assembly point has been formed, it affects

a frustoconical shape.

  The punch can also present at its end

  free mite a cylindrical part connected to the small

base of a cone trunk.

  The grooves are regularly offset an-

regularly.

  When the assembly point is carried out on aluminum sheets in particular, at the time of the spacing of the shells, these by their free edge tend

  to sink into the sheet with which they are in contact

  tact so that it forms a kind of punching A

  another feature of the invention is to remedy

Dier to this disadvantage.

  For this purpose, the free ends of the shells

are rounded.

  Finally, following a constructive detail, the

  free moths of the shells are rounded so that

  the free edge of said shells located on the side thereof

  ci cooperating with the anvil either at a distance from the sur-

  guide face greater than the distance between the free edge of the shells adjacent to the external side wall

of these.

  The invention will now be described in more detail with reference to an embodiment.

  particular given by way of example only and representing

  tee to the accompanying drawings, in which: Figure 1 is an axial sectional view showing

a punch and a die.

  Figure 2 is a sectional view along the line

2-2 of figure 1.

  Figure 3 is a sectional view along the line

3-3 in Figure 1.

  Figure 4 is a sectional view on an enlarged scale showing an assembly point obtained, according to the

prior art.

  Figure 5 shows the assembly point obtained,

according to the invention.

  In Figure 1, there is shown a set of

  for the production of an assembly point, according to the invention These tools include a tool 1 provided with a shank 2 to allow its attachment to a mandrel of a

  machine Tool 1 has a shoulder 3 intended to receive

  see a support stop 4 for a blank holder 5.

  The blank holder 5 is constituted by a block of rubber or plastic material shaped so as to

  have a circular opening 6 whose edges cooperate

  rent, on the one hand, with the support stop 4 and, on the other hand, with a shoulder 7 of the tool Tool 1 is terminated by the active part of the punch 8 which has four grooves

  9 which extend parallel to the longitudinal axis of the

  til and which are offset regularly by 90 between them.

  The active part of the punch 8 has, on the side of the

  free mite, a cylindrical part 8 a connected to the small

  base of a truncated cone 8 b with the large base adjacent to it

te at shoulder 7.

  The bottom of the grooves 9 is rounded and those

  these are open at the free end of the punch 8.

  The punch 8 is intended to cooperate with a die 10 which comprises four shells 11 which rest by their underside on a guide surface 12 of the tool 13 The guide surface 12 and the underside of the shells 10 are perfectly machined so that the shells 10 can slide freely on said surface 12. The tool 13 includes an anvil 14 against the

  lateral surface of which the shells 11 abut.

  On the tool 13 is fixed a cage 16 which

  moves a stopper limiting the sliding of the shells 11 and which has holes 17 for guiding the fingers 18

secured to the shells 11.

  The shells 11 have a groove 20 in

  which is housed a tension spring 21 in the form of an-

neau closed.

  References 23 and 24 designate two sheets,

  for example, aluminum sheets.

  Note that the free end of the shells

  11 is rounded which has the advantage, when forming the assembly point, to avoid when the shells deviate that the sheet 24 is marked Indeed, thanks to the rounded ends, the shells when they '' deviate only on sheet 24 on one point and

  no projecting part is in contact with said sheet.

  The rounding is carried out so that the free edge of the shells 11 situated on the side of the internal lateral edge cooperating with the lateral surface of the anvil 14 is located at a distance from the guide surface 12 greater than that separating said guide surface from the free edge of each shell 11 located on the side of the lateral surface

external of it.

  Tool 1 is lowered so that the clamp

  blanks 5 blocks said sheets, the punch 8 deforming by cold stamping said sheets to form the assembly point. When engaging the punch 8, we form

  simultaneously in the sheets 23 and 24 of the cylindrical cavities

  bricks 26 and 27 on one side and on the other side of the sail-

  lies 33 and 34 respectively As the shells 11 which form the matrix 10 are held by the elastic ring 21, at the time of stamping, said shells move apart to abut against the cage 16 so that it is formed by creep, in the vicinity of the bottom 30 of the cavity 27, an enlargement 31, while in the projection 33 of the sheet 23 a flare 32 is formed by creep so that an internal connection is thus produced between the sheets 26 and 27 The assembly point is then released from the

  punch and matrix We can thus assemble, by

  reading a series of regularly spaced assembly points

these, two sheets and even three.

  As seen in Figure 5, the grooves 9 of the punch 8 form in the cavity 26 four beads which extend parallel to each other from the bottom

  from the cavity 26 towards the free edge of the latter.

  Figure 4 shows in section a stitch

  wiring carried out with a conventional punch and the same references have been reported in this figure as those used to designate different corresponding parts of the assembly point in FIG. 5, but assigned the letter

"at.

  As seen in this figure 4, the thick-

  sor "L" of the sheet 23 a in the part located above the flare 32 a and between the projection 33 a and the

  cavity 26 a is lower than for the other parts.

  The formation of the beads 35 (see figure) allows, at the right of these beads to increase the thickness

  sor "L" and thus strengthen the assembly point.

  Of course, the invention is not limited

  to the embodiment which has just been described and represented

  We can make many modifications

  detail without departing from the scope of the invention.

Claims (6)

  1 New assembly point for sheets by flu-   cold age of the type in which one simultaneously practices in at least two superposed sheets (23 and 24) using a punch and a die, two stamped so as to form, in each of the sheets from one side, a cavity (26, 27) and on the other side a projection (33, 34), the projection (33) of the first sheet (23) being inserted in the cavity (27) of the second sheet (24 ), said cavity (27) of said second sheet (27) having, in the vicinity of its bottom (30), an enlargement (31), while the projection (33) of the first sheet (26) has a flare (32 ) housed in said enlargement (31), characterized in that   the cavity (26) of the first sheet (23) has a section   series of beads (35) extending substantially parallel-   from the bottom of said cavity to the free edge of it.   2 New assembly point, according to the resale   dication 1, characterized in that the beads (35) are   four in number and evenly spaced.   3 Tools for achieving the new point   assembly according to claim 1 and of the compressed type   nant a punch (8) with a blank holder (5), a die   (10) comprising an anvil (14) against which are applied   resiliently movable shells (11) on a surface   guide face (12) and limited in their displacement by   a stop (16), characterized in that the punch (8) comprises   carries grooves (9) extending parallel to the longitudinal axis of said punch (8) and opening at its end free.   4 Tools for producing the new assembly point, according to claim 3, characterized in that   that the punch (8) has a frustoconical shape.   Tools for producing the new assembly point, according to claim 3, characterized in   that the punch (8) is terminated by a cylindrical part   that (8a) connected to the small base of a cone trunk (8b).   6 Tools for producing the new assembly point, according to claim 3, characterized in   that the grooves are regularly angularly offset.   7 tools for producing the new assembly point, according to claim 3, characterized in   that the free ends of the shells (11) are rounded   dies. 8 Tools for producing the new assembly point, according to claim 7, characterized in   that the free ends of the shells (11) are rounded   dies so that the free edge of said shells, if-   killed on the side thereof, cooperating with the anvil, or at a distance from the guide surface greater than the distance separating the free edge of the shells adjacent to   the outer side wall of these.