EP0139666A1

EP0139666A1 - Method for fabricating punched pieces with material saving

Info

Publication number: EP0139666A1
Application number: EP19840900965
Authority: EP
Inventors: Rudolf Styner
Original assignee: Styner and Bienz AG
Current assignee: Styner and Bienz AG
Priority date: 1983-03-15
Filing date: 1984-03-15
Publication date: 1985-05-08
Also published as: AU2652384A; WO1984003647A1

Abstract

Dans une première étape d'usinage, on retire sous forme de chutes (7), une grande partie des rognures se trouvant entre les pièces à découper (1', 1'') voisine sur le matériau de départ. Les parts de matériau restants (5) sont separés ou découpés plus tard, lors d'une second étape d'usinage. Ce procédé permet de rapprocher les contours de pièces à découper voisines (1', 1'') jusqu'à un écartement (x) égal ou inférieur à l'épaisseur du matériau. Par rapport aux procédés de découpage habituels au cours desquels est retirée la partie découpée et non la chute comme c'est le cas ici, il est possible d'atteindre un gain de matériau pouvant aller jusqu'à 2.5%. Les parties découpées ainsi formées sont utilisées en particulier pour un usinage supplémentaire en tant que parties de parois de récipient, par exemple des couvercles de fermeture de conserves ou des couvercles de boîtiers de batteries.In a first machining step, a large part of the parings located between the pieces to be cut (1 ', 1' ') are removed in the form of scrap (7) on the starting material. The remaining material parts (5) are separated or cut later, during a second machining step. This process allows the contours of neighboring pieces to be cut (1 ', 1' ') to be brought together up to a distance (x) equal to or less than the thickness of the material. Compared to the usual cutting methods during which the cut part is removed and not the drop as is the case here, it is possible to achieve a material gain of up to 2.5%. The cut parts thus formed are used in particular for further machining as parts of container walls, for example can closure lids or battery case lids.

Description

Process for the material-saving production of stamped parts

Technical field;

The invention relates to a method according to the

Preamble of claim 1.

State of the art:

In known stamping processes, a plurality of stamped parts are often produced simultaneously from a starting material in the form of a sheet or a strip by a single stamping process using a multiple tool. The individual stamped parts are removed from the plane of the original starting material immediately after the stamping process or fall down from the plane mentioned due to gravity. The waste remaining in the plane of the original starting material has to be discharged as an unstable perforated plate, which is particularly difficult with high-speed machines. In order to overcome these difficulties, it is in any case necessary to keep the minimum width of the webs remaining between adjacent punched-out openings in the order of 2 to 3 material thicknesses or at least 1 mm. As a result, the raw material is used poorly.

In such a procedure it is known to punch out triangles of material between the disks before punching out circular disks before the sheet is tinned in order to eliminate unnecessarily tinned sheet as waste. However, the disks are later punched out in a conventional manner, and the same or more pronounced problems remain with regard to the stability of the waste grid to be removed (US Pat. No. 2,378,041).

It is also known to cut internally toothed washers from sheet metal in such a way that the contours of the Disks are located directly in the sheet without clearance. In this case, parts of the contours are first cut out by pushing the material out of the original plane of the material, then the remaining triangles of material are punched out between the parts, and the disks remain attached to each other in strips and are only separated at the consumer (US PS 2 352 118). This known method does not allow the production of flat disks or circular blanks with clean edges, as are necessary for the production of can bodies or covers, because the material has to be deformed in part from its plane, which leads to uneven, unclean transitions to the non-deformed ones Material bridges between adjacent disks. It is unclear how the triangles remaining between cut-out disks and material bridges are to be punched out cleanly from the uneven material.

Disclosure of the Invention; The aim of the entire invention is to save material compared to the conventional methods for obtaining flat round blanks from flat material for container manufacture without problems with the removal of the waste or with the quality of the round blanks. The solution is described in the characterizing part of claim 1. Since material triangles are punched out in the first step to form part contours of the round blanks, in the second step all that remains is to cut the bridges between adjacent parts. The transport between the two steps is ensured by all material remaining quasi rigidly connected via the bridges. The openings punched out in the first step serve as transport and positioning aids. In the first step, the tools for punching out the triangles are preferably designed with rounded "corners", the radius of which may correspond, for example, to approximately half the material thickness and preferably between see 0.15 and 1 mm. The material bridges thus have rounded free sides of a certain width at their ends, which permits subsequent clean punching or cutting through these bridges with the accuracy to be expected for punching tools.

The material saving is particularly important in an application where, in the first step, triangles are punched out, which define circular parts with overlapping contour lines, whereupon the bridges between adjacent parts are cut through. Then, with optimal use of the material, slightly out-of-round blanks are formed, but this does not have a disadvantageous effect on the container manufacture, since the out-of-roundness only _{leads to} certain indentations or bulges on the flanged edges of the container body and lid.

Brief description of the drawings;

In the following the method is described for example with reference to the drawing.

Fig. 1 shows the arrangement of circular punched parts which are used for further processing e.g. as a can end cover, on a sheet-like starting material,

2 shows a further arrangement of essentially circular stamped parts on a sheet-like material which has been specially cut to optimize the use of space,

3 and 4 show the relationships according to FIG. 2 on a larger scale and

FIG. 5 shows a stamped part according to FIG. 2 after it has been further processed into a can end cap.

O PI Best way to carry out the invention; In the production of stamped parts in the form of round disks, a metal sheet of length a, width b and thickness c is used as the starting material. Instead of the sheet, a sheet metal strip from a roll can also be used. However, metal sheets are preferably used when the starting material has to be provided with a coating layer, for example a food-grade lacquer, before the actual stamping process.

To make the best possible use of the starting material, i.e. To produce a minimal amount of waste, the material is preferably used in the form of a sheet metal blank according to FIG. 2. The individual stamped parts are arranged in staggered rows in the form of a tight disc pack. Under the condition that the contour of the stamped parts is round, a theoretical utilization of 86.7% of the surface would be possible with mutual punctiform contact of adjacent stamped parts. However, since punching tools have finite dimensions, the disks must be arranged with a mutual contour spacing x. In conventional stamping processes, this distance x is 2 to 3 times the material thickness c or approximately 1 mm. With the method according to the invention, this distance x can be reduced to values equal to or less than the material thickness c.

This short distance is possible thanks to the use of two processing steps. As can be seen from FIG. 1, in the first processing step the material lying between adjacent disks is punched out in the form of a section 7 each having three lobes.

During this first step, all sections 7 located on the starting material or only individual, e.g. in individual rows, at the same time

O PI to be punched. It is only essential that a part of the contours of adjacent stamped parts is formed by punching out this section 7. The tips have rounding radii r, which rounding radii r complementarily connect the transition point of the contour lines 2 ', 2 "which temporarily delimit the disks with the material bridges 5 formed in the first machining step.

After the end of the first processing step, the punching waste is already removed from the level of the starting material except for the material bridge 5. However, the individual disks are still connected in a dimensionally stable manner via the material bridges and can be removed in the form of a sheet-like structure from the area of the first punching tools.

The openings formed by punching out the sections 7 serve as engagement openings for transport mechanisms. These guide and position the structure of connected disks under the second punching tool, by means of which all material bridges along the geometric lines 4 ¹ , 4 "of two adjacent disks are punched away simultaneously or successively.

It may be expedient to notch one or both surfaces of the individual disks before punching out the material bridges 5 in order to e.g. to form a pull tab. Also punching a pouring hole, e.g. in drop form, possible. It goes without saying that the negative openings of the sections 7 are also of great advantage as ideal gripping openings for transport and positioning auxiliary elements in such intermediate processing steps.

The material-saving production of can end caps is described as a further example. Like Fig. 5

O PI shows, the peripheral area of a lid 8 is rolled together with the edge area of the can jacket 9 to form a fold 10.

It has been shown that in the area of the fold 10 slight flattenings Z / 2 of the largely circular contour of the punch disc forming the cover 8 do not have any negative influence on the production and functionality of the doser.

The production of appropriately designed panes, however, now permits a raw material utilization which is better than 86.7%.

For this purpose, the disks according to FIGS. 2 to 4 are arranged on the starting material in such a way that the geometric lines (here circles) forming the majority of the final contour (here circles) of two adjacent stamped parts intersect on the associated material bridge.

Proof that the material utilization is better than 86.7% (densest circular packing) is the fact that further circles 11 lying within the individual stamped parts touch each other at points. These circles 11 alone use 86.7% of the starting material. Accordingly, the ring segment area 12 delimited by the final contour and the further circle can be designated as material gain.

In the first processing step, sections 13 are cut individually or all of them are punched out simultaneously from the sheet of material to form rounded radii r in the area of the material bridge 5. The material bridge as such is essentially linear.

In the second processing step, the adjacent stamped parts are separated using cutting tools. Possible Before parting line geometries are listed in claim 3. In particular in the case of wavy or toothed dividing lines, the stability of the connection point 10 with the can jacket is substantially improved.

Thanks to this arrangement of the stamped parts, a material gain of 2 to 2.5% can be achieved in comparison to conventional stamping processes.

In addition to this material gain, the stability of the stamped parts connected in the form of a perforated sheet-like structure after the first processing step is also important.

FIGS. 3 and 4 show further details of the embodiment according to FIG. 2. It is assumed that the separating cut takes place along a straight line 6. The material triangles 13 punched out in the first step also have rounded corners, the radius of which is r 1 corresponds to and corresponds at least to approximately half the material thickness. As shown in FIG. 4, the section line 6 runs partly inside, partly outside the circular circumferential line of the disk or blank to be produced, which is indicated by dashed lines, in such a way that at the ends of the cutting lines 6, tips 14 are formed which protrude slightly beyond the circular circumferential line. These contours of the disks, which run slightly inside and slightly outside the circular circumferential line, play no role in the flanging with the container body according to FIG. 5, but do allow the considerable material savings mentioned above.

In FIG. 4, the intersection line 6 is deliberately not drawn completely symmetrically to the adjacent disks or not exactly through the two intersection points of the circular circumferential lines in order to indicate that these are slightly irrelevance does not matter. In any case, the cut lies clearly within the rounded, exposed sides r of the bridge between adjacent panes, and there is no danger that there will be pointed eyebrows, as is the case in the case of triangles which are pointed at the intersections of the circular contours and are not exactly symmetrical guided cut could be the case.

The stamped parts can also be separated in the second processing step by a cutting process other than cutting. For example, the desired Trennli¬ nienform be mapped by means of a notch to be subsequently separated by tearing off or angling the notify hard ^"stampings.

The method according to the invention is not limited to the production of round or essentially round stamped parts. It is equally possible, e.g. to produce elliptical parts to save material. It is also essential for such parts that all or a large part of the waste material is punched out by the first processing step. What is not shown in the figures, in addition to the triangular tips 7 and 13, the edge portions 7 'and 13' are stamped out step by step.

Claims

Claims:

1. A method for the material-saving production of circular or elliptical stamped parts (1) from a thin-walled material in the form of a sheet or a band, which stamped parts are intended for further processing as parts of the container wall, characterized in that in a first processing step that between adjacent Material lying on the stamped parts is punched out such that a part (2 ', 2 ") of the contours (3', 3") is formed by at least two immediately adjacent stamped parts (1 *, 1 "), which part of the individual stamped part contour runs along a self-contained geometric line (4 ', 4 ") and that each stamped part (1 ¹ ) remains connected to the immediately adjacent stamped parts (1", 1 "') via a respective material bridge (5), wo¬ in the case of the geometric lines extending over the material bridge, intersect or are spaced such that the shortest distance (x) between them is less than or equal to that Material thickness is, and that in a second processing step, the material bridge is cut or punched away along the geometric lines.

2. The method according to claim 1, characterized in that at the points of contact of the material bridge (5) with the geometric lines (4 ', 4 ") by the first processing step each have a radius of curvature less than 1 mm, approximately equal to half the sheet thickness, preferably at least 0 , 15 mm is formed.

3. The method according to any one of the preceding claims, characterized in that by the second machining step, the material bridge (5) along a straight or simply curved or wavy or with pointed or flattened teeth

"ξOHET O PI provided tooth-shaped dividing line (6) is cut.

4. The method according to any one of the preceding claims, characterized in that between the first and the second processing step, one or both surfaces of the still connected stamped parts are structured, e.g. is or will be notched, or at least one opening, e.g. a hole that is punched.

5. The method according to any one of the preceding claims, characterized in that the material is black plate.

6. Stamped part, produced by the method according to claim 1.

7. Container made with a stamped part according to claim 6.

8. Application of the method according to any one of claims 1- 5, characterized in that circular stamped parts (2) with at the interfaces (6) within the geometric circular line prepares places and to a container body (9) or lid (8) with indentations (6) are formed on the edge, whereupon the edge is crimped to the container lid or fuselage.