Drawing and coining die for manufacturing metal containers and the like

Abstract: A drawing and coining die for metal containers, comprising: a matrix (1), which is connected to a base (3) associated with a moving slider of a press and comprises a sliding plate (4) provided with elastic means (4a) in contrast with the base; a male element (5), which is connected to a base (6) associated with a footing of the press and is shaped so as to make contact with an edge of the container; a blank holder (8), which is slidable in contact with the male element (5), is provided with movement means (9, 10) and comprises means for resting and centering a disk (7) that constitutes the material to be processed.

Description: The invention relates to a drawing and coining die for manufacturing metal containers. GB-609907 discloses a die and punch for making pans which has a combination of features as recited in the precharacterizing portion of the appended claim 1. It is known that metal containers, such as for example pans in their many constructive shapes, and similar items, are manufactured by means of dies associated with a press. The finished product is obtained starting from a metal disk which is first drawn by the action of a male element combined with a matrix, assuming the intended shape without substantial changes in thickness, and with a final coining to obtain a shape which is modulated with different thicknesses. The aim of the present invention is to provide a die which has improved characteristics with respect to existing dies. In accordance with the invention, there is provided a drawing and coining die for manufacturing metal containers as defined in the appended claim 1. Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment thereof, illustrated by way of non limitative example in the accompanying drawings, wherein: Figure 1 is a view of the die of the present invention in the open condition; Figures 2 and 3 are views of successive steps of the closure of the die; Figure 4 is a view of the die of the present invention in the closed condition with the finished part; Figures 5 and 6 are enlarged-scale views of details of the circled regions of Figure 4; Figures 7 and 8 are views of successive steps of the opening of the die. With reference to the above Figures, 1 designates a matrix, which is connected by means of screws 2 to an upper base 3, which is adapted to be associated with a moving slider of a press, and the reference numeral 4 designates a plate slidable within the matrix in contrast with elastic means, such as a spring 4a, which are interposed between the plate and the upper base 3. The reference numeral 5 designates a male element which is connected, by means of screws 5a, to a lower base 6 which is adapted to be associated with a footing of the press. The male element is shaped so as to make contact in a region 5b, as shown in the detail of Figure 6, with an edge of the container, designated by 7b in Figures 4 to 8, which is obtained from a disk designated by the reference numeral 7 in Figures 1 and 2 thanks to several modification steps such as the step designated by 7a in Figure 3. Figure 6 clearly shows that the male element 5 is shaped so as to make contact with the edge of the container 7b except for a band which is located in an outer peripheral region of the edge, at which a burr 7c, mentioned hereinafter, has formed. Figure 5 instead illustrates another feature of the die according to the invention consisting in that, as will be explained hereinafter, the plate 4 is slightly larger than the dimensions of the end cross-section 5c of the male element 5. The reference numeral 8 designates the blank holder, which is slidable hermetically within a chamber 9 formed by a wall 9a; compressed air is fed into the chamber 9 through a duct 10 and constitutes means for moving the blank holder according to an automatic operating criterion described hereinafter. The blank holder 8 has a band which is located in the peripheral region proximate to the male element 5 and protrudes onto the impression formed in the matrix so as to form a shape which is complementary to the shape of the container. Accordingly, a clearance 8a which is smaller than the thickness of the burr 7c is formed between the blank holder 8 and the male element 5 and comprises, at its upper face, a portion of space 8b for containing and centering the disk 7 that constitutes the material to be processed. The portion of space is provided with a region 8c which allows the passage of the finished product; different means for the resting and centering of the disk might comprise repulsion elements accommodated within the blank holder 8. The operation of the invention is now described starting from the condition in which the die is open, as shown in Figure 1. The upper base 3 moves downwards and the matrix 1, after making contact with the disk 7 in the condition of Figure 2, draws the disk in contact with the male element 5, with a descent of the blank holder 8 which is controlled by the underlying compressed air in the chamber 9. The configuration of Figure 3 is thus obtained, with the plate 4 in contact with the now-deformed material 7a; the further descent of the base 3, which occurs with an upward sliding of the plate 4 and with a compression of the spring 4a, completes the drawing operation and produces the final coining operation with a compression of the product which causes a migration of material within the impression so as to give said product the configuration 7b having a modulated thickness as shown in Figures 4 to 8. Figure 4 indeed illustrates the situation in which the die is closed and the product is perfectly formed. During the coining step, the material that migrates inside the impression between the male element 5 and the matrix 1 reaches the regions of the impression where the clearance shown in Figure 5 between the matrix 1 and the plate 4 and the clearance shown in Figure 6 between the matrix 1 and the male element 5 are provided when the migration is ending. This eliminates the passage of material into the clearance between the matrix and the plate, causing a consequent lack of burr, and causes a controlled passage of material into the clearance between the matrix and the male element to form minimal burr 7c or even no burr at all. In the first step of the ascent of the base 3, which ends with the configuration of Figure 7, the plate 4 remains in contact with the finished part 7b, which is locked on the male element 5, preventing it from remaining attached to the matrix 1, which would interrupt the continuous automatic operation of the die. While the base 3 continues its ascent, the blank holder 8 also rises by being pushed by the compressed air in the chamber 9, which is adjusted by adapted means connected to the duct 10, makes contact with the burr 7c or, if no burr is present, it makes direct contact with the peripheral band of the edge of the container 7b that is not covered by the region 5b of the male element, and causes the separation of the finished part 7b from the male element 5 and its lifting, which continues, advancing through steps such as the step shown in figure 8, until it can be received by an extractor arm, passing through the region 8c. The burr 7c is then removed with a finishing pass. The die according to the present invention is susceptible of numerous modifications and variations within the scope of the claims. Thus, for example, the blank holder 8 can be provided with movement means which comprise shafts protruding from the footing of the press and managed by a fluid-actuated system with which the press is equipped, or the movement means can comprise elastic elements. The male element may also be shaped so as to make contact with the edge of the container 7b as a whole; in this case, the blank holder no longer has a band which protrudes onto the edge and therefore is no longer able to act as an element for extracting the finished part from the male element as described. Within the scope of the claims, all the details may be replaced with other technically equivalent elements; the materials used, as well as the shapes and the dimensions, may be any according to requirements. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: A drawing and coining die for manufacturing metal containers comprising a matrix (1) and a male element (5), shaped so as to make contact with an edge (7b) of the resulting pan, characterized in that said matrix (1) is connected to an upper base (3) adapted to be associated with a moving slider of a press and comprises a plate (4) slidingly associated at the bottom and is provided with elastic means (4a) in contrast with said upper base (3), said male element (5) being connected to a lower base (6) adapted to be associated with a footing of the press, the die further comprising a blank holder (8), which is slidable in contact with the male element (5), and which is provided with underlying movement means and comprises, at an upper face, means for resting and centering a disk (7) that constitutes the material to be processed. The die according to claim 1, characterized in that the male element (5) is shaped so as to make contact with the edge (7b) of the resulting container, except only for a band located in the outer peripheral region of the edge, the blank holder (8) being adapted to make contact with the matrix (1) by having a band which is located at an inner peripheral region and protrudes onto an impression formed in said matrix so as to form a shape which is complementary to the shape of the container. The die according to claim 1, characterized in that the male element (5) is shaped so as to make contact with the edge (7b) of the resulting container as a whole. The die according to claim 1, characterized in that the plate (4) is slightly larger than the dimensions of an end cross-section of the male element (5). The die according to claim 1, characterized in that the blank holder (8) is slidable hermetically in a chamber (9) for containing, in a region below said blank holder (8), compressed air which constitutes a movement means and is fed through a feed duct (10) by actuation means according to an automatic operating program. The die according to claim 1, characterized in that the movement means for moving the blank holder (8) comprise shafts which protrude from the footing of the press and are controlled by a fluid-actuated system with which said press is equipped. The die according to claim 1, characterized in that the blank holder (8) is provided with underlying elastic movement means. The die according to claim 1, characterized in that the blank holder (8) comprises, at the upper face, a portion of space (8b) for containing and centering the disk (7) that constitutes the material to be processed, said portion (8b) being provided with a region (8c) which allows the passage of the resulting container. The die according to claim 1, characterized in that the blank holder (8) comprises, at the upper face, repeller elements for centering the disk (7) that constitutes the material to be processed.

Inventors: MARIN VISINO, MARIN, VISINO
Applicants: ATTREZZERIA MV & C SNC, ATTREZZERIA M.V. DI MARIN VISINO & C. S.N.C.
Application year: 1998
Main classification: B21D22
IPC codes: B21D22, B21D45