EP0100271A1 - Simplified construction of tools to widen the use of strip tools in the production of metallic articles in small or intermediate series - Google Patents

Abstract

The invention relates to the manufacturing of metal parts with a strip. To make it possible to vary the pitch and therefore to make different parts in the same structure, it comprises a series of work stations (punch holder and matrix) whose dimensions are such that they allow the spacing of the punches (20, 21, 22, 23) at the chosen pitch. Application of the tape manufacturing technique to small and medium series.

Description

The present invention relates to an assembly for the implementation of operations, such as cutting, bending, etc. a strip of sheet material, for example a strip of metallic sheet, advancing in successive steps of a particular length to the workpiece, said assembly comprising as many punches as operations to be performed, each punch being mounted in a punch holder opposite a die to form a work station and the various punch holders and dies being mountable respectively in the same sole which can be secured to the upper jaw of a press and in the same frame secured to the lower jaw of said press.

Until now, when it is desired to manufacture repetitive series of parts with a strip, a specific assembly is produced for the part in question in which the spacing between the work stations corresponds to the pitch not particular to this part. These assemblies are expensive and their realization can only be envisaged if the series of parts to be manufactured is large enough to allow the amortization of the price of the tools.

Consequently, it is not possible to produce medium series (of the order of 6000 pieces per month) or small series (of the order of 500 pieces per month).

In the case of such series, as many tools are used as there are operations to be carried out, each tool comprising, in addition to the punch, the punch holder and the die specific to the operation, a specific carcass mounting on the press and at least one pair of guide columns.

In addition to the fact that the production of these individual tools is of a high cost price, their use requires time and manpower, the part being produced must be presented successively to each of the tools.

The object of the present invention is to reduce the price of the tooling used for strip manufacturing by not making it more specific to the part manufactured but adaptable to the production of different parts, and thus to allow, on the one hand, substantial savings during the production of large series of parts and, on the other hand, strip production of small and medium series.

To do this, elle.propose a set which includes a series of workstations whose dimensions are such that they allow to adapt the spacing of the punches to the particular advancement step to the manufactured part.

In other words, depending on the part manufactured, the point of attack of the worked blank may vary to the left or to the right relative to the center of the work station, or there may be several punches per work station.

This considerably reduces the cost of the investment, in particular because, for a given part, one only has to manufacture the tool elements coming directly into contact with the part to be produced, that is to say say punch holders, punches and dies, the rest of the structure being built once and for all according to the press to be fitted.

As a result of the lowering of the cost. tooling, it becomes economically possible to work with the strip on small or medium series.

In a preferred embodiment of the invention, the punch holders can be immobilized in the common sole by penetration into suitable openings provided in said sole and blocking by means of punch covers, while the dies are immobilizable in suitable cutouts provided in the common frame, the punch holders, the openings, the punch covers, the dies and the cutouts are all of standard dimensions.

Thanks to this standardization, it is possible to replace a punch holder by another and a die by another to modify the succession of operations carried out according to. the invention, keeping the other elements of the assembly unchanged.

Thus, the assembly according to the invention comprises two categories of constituent elements, namely invariable standardization elements comprising the upper sole, the punch covers, the die holders and the frame, and interchangeable standardized elements comprising the door - punches and dies.

The invention is also applicable to take-back tools, for example, for bending parts prepared elsewhere.

In this case, the tool comprises a standardized opening sole for the establishment and blocking of a particular punch and a frame with standardized cutout for the establishment and blocking of a particular corresponding matrix.

The only replacement, in the standard structure, of the punch and of the die makes it possible to modify the operation implemented at low cost.

• - les figures la et lb sont des vues en coupe respectivement d'un outil de flan et d'un outil de cambrage, tels qu'utilisés selon l'art antérieur pour la fabrication d'une première pièce en petite pu moyenne série,
• - les figures 2a et 2b sont des vues de dessus du flan tel que travaillé par les outils des figures la et 1b,
• - les figures 3a et 3b sont des vues en coupe respectivement d'un outil de flan et d'un outil de cambrage tels qu'utilisés selon l'art antérieur pour la fabrication d'une deuxième pièce en petite ou moyenne série,
• - les figures 4a et 4b sont des vues de dessus du flan tel que travaillé par les outils des figures 3a et 3b,
• - la figure Sa montre, en vue de dessus, la transformation d'un flan pour la fabrication, selon l'invention, de la première pièce des figures la et lb,
• - la figure 5b montre, en coupe, l'ensemble selon l'invention permettant d'effectuer la succession d'opérations illustrées à la figure 5a,
• - la figure 6a montre, en vue de dessus, la transformation d'un flan pour la fabrication, selon l'invention, de la deuxième pièce des figures 3a et 3b, cette fabrication ayant encore à être achevée par un cambrage,
• - la figure 6b montre, en coupe, l'ensemble selon l'invention permettant d'effectuer la succession d'opéra- tionsillustrées à la figure 6a, et
• - la figure 7 montre, en coupe, un outil standardisé pour opération de reprise.

The invention will be better understood on reading the following description made with reference to the appended drawings in which:

• FIGS. 1a and 1b are sectional views respectively of a blank tool and of a bending tool, as used according to the prior art for the manufacture of a first part in small or medium series,
• FIGS. 2a and 2b are top views of the blank as worked by the tools of FIGS. 1a and 1b,
• FIGS. 3a and 3b are sectional views respectively of a blank tool and a bending tool as used according to the prior art for the manufacture of a second part in small or medium series,
• FIGS. 4a and 4b are top views of the blank as worked by the tools of FIGS. 3a and 3b,
• - Figure Sa shows, in top view, the transformation of a blank for the manufacture, according to the invention, of the first part of Figures la and lb,
• FIG. 5b shows, in section, the assembly according to the invention making it possible to carry out the succession of operations illustrated in FIG. 5a,
• FIG. 6a shows, in top view, the transformation of a blank for the manufacture, according to the invention, of the second part of FIGS. 3a and 3b, this manufacture still having to be completed by bending,
• FIG. 6b shows, in section, the assembly according to the invention making it possible to carry out the succession of operations illustrated in FIG. 6a, and
• - Figure 7 shows, in section, a standardized tool for recovery operation.

If we refer to Figures 1a, 1b, 2a and 2b, we see the realization, according to the prior art, of a trapezoidal piece arched by cutting in a blank (Figures la and 2a) and bending (Figures lb and 2b). Two independent tools are provided for carrying out the manufacturing, each of said tools comprising its own punch cover 1 and its own frame 2. The relative alignment between the punches 3a and 3b and the dies 4a and 4b is ensured, in each tool, by ball columns not shown. The tool of the figure cuts it out the trapezoidal piece in a blank 6 and the tool of figure 1b gives it the desired camber.

Figures 3a, 3b, 4a and 4b show the embodiment, also according to the prior art, of a substantially rectangular part extended by two tongues and arched. Again, there is provided a blank cutting tool. (Figure 3a) and a bending tool (Figure 4b) completely separate from each other and each comprising their own punch cover 1, their own frame 2 and their own ball columns (not shown).

The tool of FIG. 3a cuts the substantially rectangular part 7 from a blank 6 and the tool of FIG. 3b gives it the desired camber.

Figures 5 and 6 which illustrate the invention show that, unlike the prior art, a series of complete and isolated tools is not used for the manufacture of small and medium series, but, as in the conventional tape manufacturing technique, a succession of workstations comprising, in a common structure, only the parts of tools ensuring the expected function.

Unlike the conventional technique, however, the common structure is not specific to a given workpiece but can be used for any parts requiring different advancement steps.

If we refer in particular to Figures 5b and 6b, we see that the assembly according to the invention comprises a lower frame 8, on which is mounted a die holder 9 having several circular cutouts 10 of the same diameter. These cutouts 10 each receive a circular matrix 11 in two parts 11a and 11b. Part 11a of matrix comes to rest on a shoulder 12 defined by the cutout 10 in the die holder 9 and the part llb of matrix, which fits into a cutout 13 provided in an elastic blank press 14, rests on part 11a of matrix , with interposition of the blank 6 to be worked. The assembly further comprises an upper sole 15 having as many circular openings 16 of the same diameter as the die holder 9 has cutouts 10, which openings are adapted to receive punch holders 17 facing each other. dies 11. Each punch holder 17 is mounted on a punch cover 18 which is blocked in the upper sole 15 at a shoulder 19 provided in the opening 16.

As is clear from FIG. Sb, the frame 8, the elastic blank presser 14, the upper sole 15 and the punch covers 18 are invariable elements of the structure while the punch holders 17 and the dies 11 are interchangeable . The dimensions of the interchangeable elements and the invariable elements are standardized so that it is possible to mount the interchangeable elements at any position in the assembly.

In the particular case of FIG. Sb, three work stations are provided which are, from left to right, a drilling station, a pre-diverting station and a bending and separation station.

More specifically, the first station comprises two cylindrical punches, the second station a pre-diverting punch 21 and the third posted a bending punch 22 and a separation punch 23. There are provided, in a manner known per se, 24 pilots to adjust the blank advance 6.

There are in fact a couple of punches of each aforementioned type per work station so that each operation prepares two pieces 5 head to tail, as is clear from FIG. Sb. However, only the manufacture of the parts 5 will be described, the large base of which is directed towards the base of the figure. At the first step of the blank 6, the punches 20 pierce the holes 25 and in the step following the holes 26. After a certain number of steps, the blank 6 reaches the position of pre-diversion where the punch 21 cuts the cutouts 27 and 28. After a new number of steps, the blank 6 reaches the bending and separation station where the punch 22 cambers the piece 5 along line 29, after which the punch separation 23 completes the cutting of the part at 30. It is given to the interchangeable standardized parts, and in particular to the punch holders 17 and to the dies 11, of sufficient dimensions so that the spacing between the punches 20 can be varied , 21,22,23 of successive workstations and adapt this spacing to the pitch of advancement of the blank.

The method of fixing the punches in the punch holders has not been shown. It can be produced in any suitable manner, in particular by screws and pins.

As can be seen from FIG. Sa, only four ball guide columns 30 are required for the entire assembly.

The assembly shown in Figures 6a and 6b has the same basic structure as that shown in Figures Sa and Sb, and similar parts are designated by the same references. This time, a part 7 is prepared by drilling (1st station) and cutting (2nd station), the 3rd station being left vacant. FIG. 6 shows, at this 3rd station, the method of fixing the blank press 14 and the matrix 11. It is clear from the comparison between FIGS. 5d and 6d that, in the 2nd work station, the punch 21 does not occupy the same position as the punch 23, this, to adapt the point of attack to the pitch of advancement of the blank and, therefore, to the particular piece.

Figure 7 shows a recovery tool which can be used for the bending of the part 7 as coming from the assembly of Figure 5b. The tool is designed according to the same principle as the assemblies in FIGS. 5b and 6b and, here again, the similar parts are designated by the same references. The comparison with the isolated bending tool in FIG. 3b clearly shows the difference in design between the known tool and the new tool.

It appears from the present description that the invention makes it possible to considerably reduce the cost of the tooling used for the manufacture of large series of parts at the tape and that it allows this band work technique to be used for small and medium series, the price of the tools no longer having to be justified by the large number of parts to be manufactured. Finally, it reduces the risk of work accidents since it replaces, for the modification of the functions of a production line, the displacement of heavy tools by that of small interchangeable parts.

Claims (5)

1- Together for the implementation of operations, such as cutting, bending, etc. a strip of sheet material, for example a strip of metallic sheet advancing in successive steps of a particular length to the workpiece, comprising as many punches as operations to be performed and in which each punch is mounted in vis-à-vis a matrix to form a work station, the various punch holders (17) and dies (11) being mountable respectively in the same sole (15) solidàrisable of the upper jaw of a press and in the same frame (8) which can be secured to the lower jaw of said press, characterized in that it comprises a series of work stations whose dimensions are such. that they make it possible to adapt the spacing of the punches (20, 21, 22 and 23) to the step of advancement particular to the manufactured part. 2- An assembly according to claim 1, characterized in that the punch holders (17) can be immobilized in the common sole (15) by penetration into suitable openings (16) provided in said sole (15) and blocking by means of covers - punches (18), while the dies (11) can be immobilized in suitable cutouts (10) provided in the common frame (8), the punch holders (17), the openings (16), the punch covers ( 18), the dies (11) and the cutouts (10) being all of standard dimensions. 3- An assembly according to claim 1 or 2, characterized in that it comprises a succession of work stations comprising, in a common structure of invariable standardization (15), (18), (9) and (8), that interchangeable standardized tool parts (11) and (17) ensuring the expected function (cutting, bending, etc.). 4- An assembly according to claim 3, characterized in that the invariable standardization elements include the upper sole (15), the punch covers (18), the die holders (9) 'and the frame (8) and in that that the interchangeable standardized elements include the punch holders (17) and the dies (11). Recovery tool comprising a punch blocked in a punch holder opposite a die, said punch holder and said matrix being mounted respectively on an upper sole and a lower frame depending respectively on the two jaws of a press, characterized in that it comprises a sole (15) with standardized opening (16) for positioning and blocking a particular punch (20,21,22,23) and a frame (8) with standardized cutout (10) for the installation and the blocking of a particular matrix (11) corresponding.

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