Complex pressing die apparatus

Abstract: A complex pressing die apparatus has a plurality of upper and lower dies (20, 30, 40, 50, 60, 70) which are actua­ ted by respective hydraulic cylinder devices located in a coaxial arrangement, actuation taking place in accordance with a predetermined sequence.

Description: The present invention relates to a multi-stage sheet metal pressing die apparatus, and more precisely it relates to a pressing die apparatus for carrying out different press operations using a single die apparatus. Metal products such as automobile parts and domestic electrical goods are usually formed by pressing a metal blank using different dies and punches at different pressing stages, in accordance with the desired product shape. It is necessary to mount and dismount different dies (and punches) to and from the press machine to obtain the desired final product shape. However, such a tooling operation for mounting and dismounting different dies (and punches) is a nonproductive task. In order to increase productivity, it is necessary to minimise the time needed for tooling. To this end, various devices, such as moving beds, die lifters, or die rails have been proposed for enabling a quick tooling to be carried out. However, these devices increase the size of the press machine and the cost thereof. it also should be borne in mind that those devices themselves do not contribute directly to the pressing of the products. In addition to the foregoing, the tooling operation increases the possibility of industrial accidents, since the tooling involves transfer of large components in a large press machine. Indeed , some of these problems are solved with the press machine of EP-A-0 059 432, which discloses the combination of features according to the first part of claim 1, wherein a single pressing operation results in several working operations on sheet metal in the machine taking place in sequence through the actuation of a single press device. It is an object of the present invention to provide a pressing die apparatus which can substantially prevent industrial accidents and which can enable different press operations to be carried out without using a conventional large press machine. According to this invention, there is provided a multi-stage sheet metal pressing die apparatus for carrying out a plurality of operations on a metal sheet while the metal sheet is located at one position, comprising an upper frame holding an upper die assembly of pressing elements selected from dies and punches, and a lower frame, in axial alignment with said upper frame and holding a lower die assembly of pressing elements, characterized in that the upper frame and the lower frame are both stationary with the pressing elements of said upper die assembly being held within said upper frame for travel therewithin, the pressing elements of said lower die assembly being held within in said lower frame for travel therewithin and said pressing elements of the respective die assemblies being in axial, face-to-face alignment, each pressing element of said upper die assembly and each pressing element of said lower die assembly having associated therewith a two-way hydraulic cylinder housing a piston for advancing and retracting the respective said pressing element in one assembly towards and away from the pressing elements in the other assembly independently of the other pressing elements in the one assembly and the other assembly, the pistons of the two way hydraulic cylinders of said upper die assembly and the pistons of the two way hydraulic cylinders of said lower die assembly being in axial alignment with the axis of said upper die assembly and said lower die assembly, respectively, each piston being integral with a said pressing element which is driven on admission of fluid through said hydraulic cylinders to act on a drive surface of the piston. With this arrangement, individual hydraulic cylinder devices are used as drives for the pressing elements of upper and lower dies, instead of as drives for the press machine, as in the prior art. The coaxial arrangement of the multiple cylinder devices contributes to a realization of a compact and small die apparatus. Various press operations can be easily effected by simultaneously or successively operating the associated cylinder devices, in accordance with a predetermined sequence. For a better understanding of the invention and to show how the same can be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, wherein: FIGURE 1 is a longitudinal sectional view through a complex pressing die apparatus embodying the present invention, shown in different positions in the right and left halves of the Figure; FIGURE 2 is a longitudinal sectional view through the complex pressing die apparatus, shown in three different positions; FIGURE 3 is a perspective view of a product obtainable using an embodiment of the die apparatus of the present invention; and FIGURE 4 is a sectional view showing successive pressing stages in producing the product of Figure 3 using a die apparatus according to an embodiment of the present invention. In the illustrated embodiment, the product as shown in Figure 3 is a half of a container of a brake booster and is indicated by the reference letter P. In Figures 1 and 2 which show a die apparatus of the present invention, the pressing operations are successively effected in the alphabetical order of A, B, C, D and E. Thus Figures 1 and 2 show respectively early pressing positions A and B and later pressing positions C, D and E. The positions A, B, C, D and E correspond to the state of a starting blank at steps A, B, C, D and E in Figure 4. In Figures 1 and 2, the die apparatus is shown being used for drawing and punching. The apparatus has a lower frame 11 which has therein a lower die assembly consisting of an outer punch 20 and an inner punch 30 coaxial with the outer punch 20, and an upper frame 12 which has therein an upper die assembly consisting of a die 40, an inner die 50 in the die 40, a knockout 60 in the inner die 50 and a piercing punch 70 located innermost. The die 40, the inner die 50, the knockout 60 and the piercing punch 70 are coaxial with each other in the upper frame 12. The elements 20, 30, 40, 50, 60 and 70 mentioned above can be actuated independently of each other by respective hydraulic cylinder devices. Thus, the outer punch 20 is actuated by a piston 25 integral therewith which is slidably arranged in the lower frame 11 which serves as a cylinder for the piston 25. A cylinder chamber 81 defined by the lower frame 11 is connected to a pressurized fluid source (not shown) through a first port 26 and a second port 27 on the opposite sides of the piston 25. When the piston 25 moves forward, i.e. upwards in Figure 1, the working fluid is fed into the cylinder chamber through the first port 26 and is discharged therefrom through the second port 27. On the other hand, for the piston 25 to move downwards in Figure 1, the working fluid is fed into the cylinder chamber 81 through the second port 27 and is discharged therefrom through the first port 26. Thus, the piston 25 is a double acting piston. Similarly, the inner punch 30 has a piston 35 which is inserted in a cylinder 11a defined by the lower frame 11 for sliding travel in the cylinder 11a. A cylinder chamber 83 defined in the cylinder 11a is connected to the pressurized fluid source (not shown) through a third port 36 and a fourth port 37 on opposite sides of the piston 35. The third and fourth ports 36 and 37 correspond to the first and second ports 26 and 27 and respectively function in like manner. The die 40 has a piston 45 integral therewith which is inserted in the upper frame 12 which serves as a cylinder for sliding travel therein of the piston 45. A cylinder chamber 85 defined by the cylinder 12 is connected to the pressurized fluid source through fifth and sixth ports 46 and 47 on the opposite sides of the piston 45, respectively. When the piston 45 moves towards the lower frame 11, the working fluid is introduced into the cylinder chamber 85 through the fifth port 46 and is discharged from the cylinder chamber 85 through the sixth port 47 and vice versa. Similarly, the inner die 50 has a piston 55 which slides in a cylinder 12a formed by and integral with the upper frame 12. A cylinder chamber 87 defined by the cylinder 12a is connected to the fluid source through seventh and eighth ports 56 and 57 on the opposite sides of the piston 55. The seventh and eighth ports 56 and 57 are equivalent in function to the fifth and sixth ports 46 and 47, respectively. The knockout 60 has a piston 65 which slides in a cylinder 12b defined by and integral with the upper frame 12. A cylinder chamber 89 defined by the cylinder 12b is connected to the fluid source through ninth and tenth ports 66 and 67. The piercing punch 70 has a piston 75 which slides in the piston 65 of the knockout 60. A cylinder chamber 91 defined by the piston 65 is connected to the fluid source through an eleventh port 76. The return movement of the piston 75 is effected by a return spring 77. Scraps of blank are discharged through a scrap chute 39 within the inner punch 30. In Figures 1 and 2, the numeral 13 designates a die for supporting a starting blank against the moving die 40, 14 denotes a gate for the blank, 15 a die cushion cylinder piston for a pressure pad, and 16 a fluid port through which an oil under pressure can act on the cylinder piston 15 in order to provide a proper back pressure. The die apparatus shown in Figures 1 and 2 operates as follows. Firstly, referring to Figure 1(A) and Figure 4(A), the blank B to be pressed is inserted in the blank gate 14. At this stage, the dies and punches of the lower and upper frames 11 and 12 are all located at their initial positions (retracted positions). Next, as can be seen from Figure 1(B) and Figure 4(B), the blank B is punched by the die 40. In the illustrated embodiment, simultaneously with or shortly after forward movement of the die 40 i.e. movement downwards in the drawings, the inner die 50, the knockout 60 and the piercing punch 70 move forward together to assist the punching operation by the die 40. After that, the operation of the apparatus proceeds to the next stage shown in Figure 2(C). Here, as can be seen from Figure 4(C), a first drawing can be effected. In this first drawing stage, the outer punch 20 and the inner punch 30 in the lower frame 11 move forwards (upwards) together, and the inner die 50 and the knockout 60 in the upper frame 12 move backwards (upwards) together to serve as a knockout. As shown in Figure 2(D) and Figure 4(D), a deep drawing stage (second drawing), subsequent to the first drawing, has the working fluid pressure which is being exerted on the outer punch 20 in the lower frame 11 undergoing a reduction, and the inner die 50 moving forwards (downwards) to carry out the deep drawing. After the deep drawing ends, the piercing punch 70 moves forwards (downwards) to pierce a central portion of the blank, as shown in Figure 2(E), the blank then having the appearance shown in Figure 4(E). The scraps which are produced during piercing are discharged from the die apparatus through the scrap chute 39. The operations of the cylinder devices of the dies (and punches) in the upper and lower frames 11 and 12 can be automatically and successively or simultaneously effected in accordance with a predetermined sequence of a hydraulic control device. It should be appreciated that the illustrated dies can be replaced by other dies whose shape is appropriate to the shape of products to be pressed. As can be seen from the foregoing, with a die apparatus according to the present invention, since one or both of the upper die assembly and lower die assembly is or are actuated by the respective hydraulic cylinder devices which are coaxially arranged and which operate simultaneously or successively, different press operations can be effected without troublesome tooling (or setting-up). This results in a reduction of the time for tooling and also in a reduction in the likelihood of industrial accidents. Furthermore, a large press machine is now no longer necessary and the number of dies can be decreased, because of the complex pressing operations which can be achieved using combinations of dies. This means a minimization of the space required for the die apparatus and also a decrease in the cost of the associated devices while enabling products of a wide variety of shapes to be produced. By means of a proper geometrical arrangement of the hydraulic cylinder devices and by a proper consideration being given to the output conditions thereof, various pressing operations can be automatically carried out. It is indeed possible too, to connect the hydraulic cylinder devices to a computerised controller.

Claims: A multi-stage sheet metal pressing die apparatus for carrying out a plurality of operations on a metal sheet while the metal sheet is located at one position, comprising an upper frame (12) holding an upper die assembly of pressing elements selected from dies and punches (40, 50, 60, 70) and a lower frame (11), in axial alignment with said upper frame (12) and holding a lower die assembly of pressing elements (20, 30), characterized in that the upper frame (12) and the lower frame (11) are both stationary with the pressing elements of said upper die assembly (40, 50, 60, 70) being held within said upper frame (12) for travel therewithin, the pressing elements of said lower die assembly (20, 30) being held within in said lower frame (11) for travel therewithin and said pressing elements of the respective die assemblies being in axial, face-to-face alignment, each pressing element of said upper die assembly (12) and each pressing element of said lower die assembly (11) having associated therewith a two-way hydraulic cylinder (12, 12a, 12b; 11, 11a) housing a piston (45, 55, 65, 75; 25, 35) for advancing and retracting the respective said pressing element in one assembly towards and away from the pressing elements in the other assembly independently of the other pressing elements in the one assembly and the other assembly, the pistons (45, 55, 65, 75) of the two way hydraulic cylinders (12, 12a, 12b) of said upper die assembly and the pistons (25, 35) of the two way hydraulic cylinders (11a, 11b) of said lower die assembly being in axial alignment with the axis of said upper die assembly and said lower die assembly, respectively, each piston (25, 35, 45, 55, 65, 75) being integral with a said pressing element (20, 30, 40, 50, 60, 70) which is driven on admission of fluid through said hydraulic cylinders to act on a drive surface of the piston. A die apparatus, as recited in Claim 1, wherein said upper die assembly includes a piercing punch (70) and said lower die assembly includes a discharge chute (39) in axial alignment with said piercing punch for discharging from said die apparatus scrap blanks produced with said punch.

Inventors: HOSHI HIDEO, HOSHI, HIDEO
Applicants: HOSHI HIDEO, HOSHI, HIDEO
Application year: 1987
Main classification: B21D37
IPC codes: B21D35, B30B1, B30B15, B21D28, B21D24, B21D37