Manufacturing method for cylindrical products and transfer press machine

Abstract

The present invention discloses a technology capable of manufacturing cylindrical products with higher shape quality than conventional products. [Solution] The manufacturing method disclosed herein is a manufacturing method in which a cylindrical product 90 is manufactured by punching out a bottom wall 92 from a cylindrical intermediate product 91 having a non-circular bottom wall 92, and a punching preparation step is provided before the punching step, in which the bottom wall 92 is press-formed into a shape having an annular sheared portion 95 having inner and outer surfaces intersecting with the press direction, and a bulging portion 94 surrounded by the annular sheared portion 95. Then, in the punching step, the annular sheared portion 95 is sheared to punch out the bottom wall 92.

Description

[Technical field]

[0001] The present disclosure relates to a manufacturing method for manufacturing a cylindrical product by pressing and a transfer press machine used in the manufacturing method. [Background technology]

[0002] A conventional method for manufacturing this type of cylindrical product is to press-mold a cylindrical intermediate product with a bottom at one end, and then punch out the bottom wall of the intermediate product to produce the cylindrical product (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 63-194824 A (Fig. 1) Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional manufacturing method, when the bottom wall of the intermediate molded product is non-circular, the shape quality of the end of the cylindrical product after the bottom wall is punched out may be poor. In response to this, the present application discloses a technology capable of manufacturing a cylindrical product with higher shape quality than the conventional technology. [Means for solving the problem]

[0005] A first aspect of the invention disclosed herein is a manufacturing method for producing a tubular product by punching out a bottom wall from an intermediate molded product, which is a cylindrical press-molded product having a non-circular bottom wall, the method comprising: a punching preparation process in which the bottom wall is press-molded into a shape having an annular sheared portion having inner and outer surfaces that intersect with the press direction and a bulge portion surrounded by the annular sheared portion; and a punching process in which the annular sheared portion is sheared to punch out the bottom wall.

[0006] A second aspect of the invention disclosed herein is a transfer press machine having a plurality of processing stages arranged in a row in the horizontal direction, in which a workpiece is sequentially moved to one side in the horizontal direction and processed in each of the processing stages, the plurality of processing stages including a plurality of processing stages for a cylindrical body forming process in which a flat plate is squeezed multiple times to form a cylindrical intermediate molded product having a non-circular bottom wall, one or more processing stages for a punching preparation process in which the bottom wall of the intermediate molded product is formed into a shape having an annular sheared portion having inner and outer surfaces that intersect with the press direction and a bulge portion surrounded by the annular sheared portion, and a processing stage for a punching process in which the annular sheared portion is sheared to punch out the bottom wall. Effect of the Invention

[0007] When the bottom wall of the intermediate product, which is a press-molded product, is non-circular, it is difficult for the flow of material to be uniform between the side wall and the bottom wall during press molding, and a difference in wall thickness of the side wall is likely to occur. In contrast, in the first and second aspects of the present disclosure, a bulge is formed on the bottom wall before it is punched out from the intermediate product, so that the excess material of the bottom wall is absorbed by the bulge, and the flowability of the material between the side wall and the bottom wall of the intermediate product is increased. This makes the wall thickness of the side wall of the intermediate product uniform. Then, the annular sheared portion around the bulge of the bottom wall is sheared to punch out the bottom wall and become a cylindrical product, so that the uniformity of the wall thickness of the side wall of the cylindrical product is improved compared to the conventional method. That is, according to the first and second aspects of the present disclosure, a cylindrical product with higher shape quality than the conventional method can be manufactured. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a front view of a transfer press according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view of a cylindrical product. [Diagram 3] FIG. 3A is a side view of the intermediate molded product before the punching preparation step, FIG. 3B is a side view of the intermediate molded product after the punching preparation step, and FIG. 3C is a side view of the cylindrical product and the punched bottom wall. [Figure 4] FIG. 4 is a side cross-sectional view of the processing stage for the punching preparation process. [Diagram 5] FIG. 5A is a bottom view of the intermediate molded product, and FIG. 5B is a plan sectional view of the processing stage of the punching preparation step. [Figure 6] FIG. 6A is a side cross-sectional view of the processing stage for the punching process, and FIG. 6B is a side cross-sectional view of the processing stage for the punching process immediately after punching the bottom wall. [Figure 7] FIG. 7A is a side view of an intermediate molded product before a first punching preparation step in a manufacturing method according to a second embodiment, FIG. 7B is a side view of the intermediate molded product after the first punching preparation step, FIG. 7C is a side view of the intermediate molded product after the second punching preparation step, and FIG. 7D is a side view of a cylindrical product and a punched bottom wall. [Figure 8] FIG. 8 is a side cross-sectional view of a processing stage for the first punch preparation step. [Figure 9] FIG. 9 is a side cross-sectional view of a processing stage for the second punching preparation step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] A transfer press machine 10 for manufacturing a cylindrical product 90 according to the present disclosure and a manufacturing method for the cylindrical product 90 will be described with reference to Figs. 1 to 6. As shown in Figs. 1, 4, and 6A, the transfer press machine 10 of this embodiment includes a plurality of processing stages S, each having punches 21, 22 and dies 31, 32, arranged in a row, and a workpiece is transported to one side in the horizontal direction by a transfer device 11 and pressed at each processing stage S. Hereinafter, the upstream end (left end in Fig. 1) in the transport direction of the transfer device 11 will be simply referred to as the "upstream end", and the downstream end will be simply referred to as the "downstream end", and a manufacturing method for a cylindrical product 90 (see Fig. 2) using the transfer press machine 10 will be described.

[0010] To manufacture the cylindrical product 90, in the processing stage S at the upstream end of the transfer press 10, for example, an elliptical blank is punched out of sheet metal and then drawn to form a cylindrical workpiece (not shown) with an elliptical cross section. The workpiece is then drawn multiple times in multiple processing stages S up to the second downstream end, and the axial length is extended and the cross-sectional shape is gradually changed to a rectangle smaller than the ellipse. The workpiece that has completed the press processing up to the processing stage S two stages before the downstream end becomes a cylindrical press-formed product with a rectangular cross-sectional shape and a bottom at one end.

[0011] Next, in the processing stage S just before the downstream end, the workpiece is subjected to press processing in preparation for punching, which will be described later, and in the processing stage S at the downstream end, the bottom wall of the workpiece is punched out to form a cylindrical product 90, which is then discharged from the transfer press 10.

[0012] Hereinafter, the work before the press processing in preparation for punching is referred to as the "intermediate molded product 91," the process and processing stage S in which the press processing in preparation for punching is performed on the intermediate molded product 91 are referred to as the "punching preparation process" and the "processing stage S for the punching preparation process," and the process and processing stage S in which the bottom wall 92 is punched out from the intermediate molded product 91 are referred to as the "punching process" and the "processing stage S for the punching process."

[0013] The shape of the blank and the cross-sectional shape of the cylindrical workpiece formed by drawing the blank are not limited to ellipse, but may be, for example, circular, oval, polygonal, etc. The positions of the processing stages S until the cylindrical press-molded product having a rectangular cross section is obtained, and the positions of the processing stages S where the punching preparation step and the punching step are performed are not limited to the downstream end, the downstream end, or the downstream end, but may be any positions as long as they are set according to the final shape and size of the cylindrical product 90. Furthermore, for example, a correction step or the like may be sandwiched between the processing stage S where the cylindrical press-molded product having a rectangular cross section is obtained and the processing stage S for the punching preparation step, and between the processing stage S for the punching preparation step and the processing stage S for the punching step.

[0014] As shown in Figures 3A and 3B by comparison of an intermediate molded product 91 before and after the punching preparation process, in the punching preparation process, a bottom wall 92 of the intermediate molded product 91 is formed into a two-tiered bottom shape having a bulge 94.

[0015] Specifically, as shown in Fig. 3B, the intermediate molded product 91 after the punching preparation step has an inclined surface 93A that narrows downward around the entire circumference of the lower end portion. The outer shape of the bottom wall 92 of the intermediate molded product 91 after the punching preparation step when viewed from below (i.e., the bottom surface shape) has a rectangular shape having a pair of long sides and a pair of short sides with four rounded corners as shown in Fig. 5A. In contrast, the outer shape of the planar shape of the bulging portion 94 is a rectangle that is approximately similar to the outer shape of the planar shape of the bottom wall 92, and the pair of long sides are curved so as to move away from the pair of long sides of the outer shape of the bottom wall 92.

[0016] In detail, as shown in Fig. 4, the bulging portion 94 has a bulging bottom wall 94B perpendicular to the pressing direction, and bulging side walls 94A standing upright from the four sides of the bulging bottom wall 94B. As shown in Fig. 5A, the bulging side walls 94A on a pair of long sides are curved so as to bulge inward. As shown in Fig. 4, the inner and outer surfaces of the bulging side walls 94A are substantially parallel to the pressing direction, and the entire outer surface of the bulging portion 94 is located inside the inner surface of the side wall 93 of the intermediate molded product 91. Furthermore, the bulging bottom wall 94B and the bulging side walls 94A have, for example, substantially the same thickness, or the bulging bottom wall 94B is slightly thicker.

[0017] The portion of the bottom wall 92 outside the bulging portion 94 forms an annular sheared portion 95 having inner and outer surfaces that intersect with the pressing direction. Specifically, the annular sheared portion 95 has an inner flat surface 95A and an outer flat surface 95B that are perpendicular to the pressing direction. The outer edge of the outer flat surface 95B is connected to the inclined surface 93A of the side wall 93 of the intermediate molded product 91 via a corner curved surface 95R1 with an extremely small corner R, and the inner edge of the outer flat surface 95B is connected to the outer surface of the bulging side wall 94A via a corner curved surface 95R2 with a relatively large corner R.

[0018] On the other hand, the inner flat surface 95A and the inner surface of the upper part of the bulging side wall 94A are connected by an S-shaped curved surface 94S. The S-shaped curved surface 94S curves outward from the upper part of the inner surface of the bulging side wall 94A, then curves upward and intersects with the inner flat surface 95A. The inner flat surface 95A and the inner surface of the side wall 93 of the intermediate molded product 91 are connected by a corner curved surface 95R3 having a corner R larger than that between the outer flat surface 95B and the outer surface of the side wall 93 of the intermediate molded product 91.

[0019] Here, the entirety including each of the corner curved surfaces 95R1-95R3 connected to the inner flat surface 95A or the outer flat surface 95B described above constitutes the annular sheared portion 95. More specifically, in the present disclosure, the annular sheared portion 95 is located around the bulging portion 94, and as long as it can be sheared in the processing stage S for the punching step described below, the inner and outer surfaces of the annular sheared portion 95 may be partially or entirely inclined with respect to the pressing direction. For this purpose, the angle of the portion of the inner and outer surfaces of the annular sheared portion 95 that intersects with the shearing surface with respect to the pressing direction needs to be 45-90°.

[0020] The punch 21, the die 31 and the counter punch 41 in the processing stage S for the punching preparation step shown in FIG. 4 are configured as follows.

[0021] The punch 21 has a shape in which a punch extension 21Y extends from a lower surface 21B of a rectangular punch body 21X. The planar cross-sectional shape of the punch extension 21Y is shown in Fig. 5B, and is a rectangle that is approximately similar to the planar cross-sectional shape (not shown) of the punch body 21X, and a pair of long sides are curved to be concave. That is, a pair of long sides of the planar cross-sectional shape of the side surface 21C of the punch extension 21Y are curved surfaces.

[0022] 4, the lower surface 21B of the punch body 21X and the lower surface 21D of the punch extension 21Y are each a plane perpendicular to the pressing direction. The lower surface 21B of the punch body 21X and the side surface 21A, the lower surface 21B of the punch body 21X and the side surface 21C of the punch extension 21Y, and the side surface 21C of the punch extension 21Y and the lower surface 21D are connected by corner curved surfaces 21R1, 21R2, and 21R3, respectively, and the radius of curvature of the corner curved surface 21R1 between the lower surface 21B of the punch body 21X and the side surface 21A is smaller than the other corner curved surfaces 21R2 and 21R3.

[0023] A flat step surface 31C that is perpendicular to the pressing direction and faces upward is provided in the middle of the forming hole 31Z of the die 31. The forming hole 31Z is provided above the step surface 31C with a rectangular cylindrical inner side surface 31A having a flat cross section into which the intermediate formed product 91 can just be fitted, and an inclined side surface 31B whose lower end is narrowed.

[0024] The planar cross-sectional shape of the forming hole 31Z below the step surface 31C is a rectangle that is approximately similar to the planar cross-sectional shape (not shown) above the step surface 31C as shown in Fig. 5B, and a pair of long sides are curved to bulge. That is, the forming hole 31Z below the step surface 31C has a side surface 31D that is a square tube that is approximately similar to the side surface 21C of the punch extension 21Y. Also, as shown in Fig. 4, the side surface 31D and the step surface 31C are connected by a corner curved surface 31R1.

[0025] The counter punch 41 is prismatic and its cross-sectional shape is either the same as the cross-sectional shape of the portion of the forming hole 31Z below the step surface 31C or a rectangle with four straight sides that fits exactly inside the cross-sectional shape.

[0026] The punch 22, the punch die 32 and the guide die 42 of the processing stage S for the punching step shown in FIGS. 6A and 6B are configured as follows.

[0027] The guide die 42 is supported from below by the punching die 32, and has a work receiving hole 42Z into which the intermediate molded product 91 after the punching preparation step can be inserted.

[0028] The punching die 32 has a work receiving hole 32Z smaller than the work receiving hole 42Z, and the upper surface of the punching die 32 and the work receiving hole 32Z are perpendicular to each other to form an edge portion 32E. The planar shape (not shown) of the edge portion 32E is a rectangle slightly smaller than the inner surface of the intermediate molded product 91.

[0029] The punching punch 22 is shaped like a rectangular column that is slightly smaller than the workpiece receiving hole 32Z of the punching die 32 (more specifically, the workpiece receiving hole 32Z minus a clearance suitable for shearing processing), and its bottom surface and side surfaces are perpendicular to each other to form an edge portion 22E.

[0030] The configuration of the transfer press 10 and the manufacturing method of the cylindrical product 90 in this embodiment are as described above. Below, we will explain the problems with the shape of the intermediate molded product 91 and how, in this embodiment, the intermediate molded product 91 is sent to the punching process after going through a punching preparation process, thereby solving the above problems.

[0031] Before the intermediate product 91 is completed by press molding, the bottom wall 92 is pressurized multiple times to gradually extend the axial length, and in the process, the metal material constituting the intermediate product 91 flows, causing the wall thickness of the intermediate product 91 to change. If the bottom wall 92 of the intermediate product 91 is circular, the flow of material between the side wall 93 and the bottom wall 92 is uniform over the entire circumferential direction of the intermediate product 91, and differences in the wall thickness of the side wall 93 are unlikely to occur. However, if the bottom wall 92 is noncircular as in the intermediate product 91 of this embodiment, the flow of material is unlikely to be uniform, and differences in the wall thickness of the side wall 93 are likely to occur.

[0032] Furthermore, in the final stage of multiple press forming, the radius of curvature of the corner R between the bottom wall and side wall of the workpiece becomes smaller than in the initial stage. Then, when the workpiece is further drawn in the final stage, the inner corner curved surface between the bottom wall and side wall of the workpiece before the drawing remains on the lower end of the side wall, and as shown in Fig. 3A, an annular recess 93S, generally called a "shock mark," may be formed on the lower end of the side wall 93 of the intermediate formed product 91.

[0033] Here, if the intermediate molded product 91 is punched out to form the tubular product 90 without going through a punching preparation process as in the conventional method, the wall thickness of the side wall 93 may vary depending on the circumferential position of the lower end of the tubular product 90, or an annular recess 93S may remain, which may cause problems with the shape quality.

[0034] In contrast, in the transfer press 10 and manufacturing method for the tubular product 90 of this embodiment, as described in detail below, the intermediate molded product 91 undergoes a punching preparation process before the bottom wall 92 is punched out, thereby eliminating the above-mentioned problems with the tubular product 90.

[0035] That is, the intermediate molded product 91 is transported by the transfer device 11 to a position above the forming hole 31Z of the processing stage S for the punching preparation step. At this time, the counter punch 41 is located at the top dead center, and its upper surface is located at the upper end of the forming hole 31Z. Then, the punch 21 descends and the bottom wall 92 of the intermediate molded product 91 is sandwiched between the punch 21 and the counter punch 41, and in this state, the intermediate molded product 91 descends together with the punch 21 and the counter punch 41 and is forced into the forming hole 31Z.

[0036] Then, a corner curved surface 93R (see FIG. 3A) at the outer edge of the lower end of the intermediate molded product 91 abuts against the inclined side surface 31B of the molding hole 31Z. At this time, although not shown, since a space of a step between the punch main body 21X and the punch extension 21Y is located inside the lower end of the side wall 93 of the intermediate molded product 91, the lower end of the side wall 93 easily deforms so as to be narrowed. Then, the outer edge of the bottom wall 92 abuts against the step surface 31C of the molding hole 31Z.

[0037] Then, the intermediate product 91 can no longer move downward, and as the punch 21 continues to descend, the part inside the outer edge of the bottom wall 92 is pressed by the punch extension 21Y to form the bulge 94. At the same time, the inner surface of the side wall 93 is ironed by the corner curved surface 21R1 of the outer edge of the punch main body 21X, and the annular recess 93S (see FIG. 3A) is smoothed so as to be flat, or the material of the part where the annular recess 93S is formed flows toward the bottom wall 92, removing the annular recess 93S. Furthermore, the material that has flowed toward the bottom wall 92 flows to the back of the corner between the step surface 31C and the inclined side surface 31B of the forming hole 31Z, so that the outer surface of the lower end of the intermediate molded product 91 is formed into a shape corresponding to the inclined side surface 31B, step surface 31C, and corner curved surface 31R1 of the forming hole 31Z, and the inner surface of the lower end of the intermediate molded product 91 is formed into a shape corresponding to the corner curved surface 21R1 and the lower surface 21B of the punch 21, forming an annular sheared portion 95 that surrounds the bulge 94. Then, the counter punch 41 rises and the intermediate molded product 91 is ejected from the forming hole 31Z, completing the forming of the intermediate molded product 91 in the punching preparation step.

[0038] In this way, the bulge 94 is formed simultaneously with the formation of the lower end of the side wall 93 of the intermediate molded product 91, so that the meat flows smoothly and the thickness is uniformed all around the lower end of the side wall 93. Here, when the planar cross section is rectangular like the intermediate molded product 91 of this embodiment, meat may easily accumulate on a pair of long sides of the rectangle. In contrast, in this embodiment, the pair of long sides of the bulge 94 are formed into a curved shape away from the outer edge of the bottom wall 92, so that more meat can be received without changing the wall thickness compared to the case of a straight shape. As a result, meat flows more easily into the pair of long sides of the bulge 94 than into other parts, which also makes it possible to uniform the thickness all around the side wall 93 of the intermediate molded product 91.

[0039] The intermediate molded product 91, which has been formed by the processing stage S for the punching preparation process, is transported to the processing stage S for the punching process by the transfer device 11. Then, the punching punch 22 descends, and the annular sheared portion 95 of the intermediate molded product 91 is sandwiched between the punching punch 22 and the punching die 32. The punching punch 22 continues to descend. As a result, the annular sheared portion 95 is sheared between the edge portion 22E of the punching punch 22 and the edge portion 32E of the punching die 32, and the bottom wall 92 is punched out of the intermediate molded product 91 to become a cylindrical product 90. Then, as the punching punch 22 rises, the cylindrical product 90 is discharged outside the work receiving hole 42Z, and then the cylindrical product 90 is discharged from the transfer press machine 10 by the transfer device 11 or another carrier not shown, and the production of the cylindrical product 90 is completed.

[0040] As described above, in the transfer press machine 10 and the manufacturing method of the cylindrical product 90 of the present embodiment, the bulging portion 94 is formed on the bottom wall 92 before being punched out from the intermediate molded product 91, so that the excess material of the bottom wall 92 is absorbed by the bulging portion 94. This increases the fluidity of the material between the side wall 93 and the bottom wall 92 of the intermediate molded product 91, and the wall thickness of the side wall 93 of the intermediate molded product 91 is made uniform. Then, the annular sheared portion 95 around the bulging portion 94 of the bottom wall 92 is sheared and the bottom wall 92 is punched out to form the cylindrical product 90, so that the uniformity of the wall thickness of the side wall 93 of the cylindrical product 90 is improved compared to the conventional method. That is, according to the transfer press machine 10 and the manufacturing method of the cylindrical product 90 of the present embodiment, the cylindrical product 90 having higher shape quality than the conventional method can be manufactured.

[0041] [Second embodiment] In the transfer press machine 10 and manufacturing method for the tubular product 90 of this embodiment, the punching preparation process is performed in two stages, as shown in Figures 7A to 7D, and the transfer press machine 10 of this embodiment is equipped with a processing stage S for the first punching preparation process shown in Figure 8 and a processing stage S for the second punching preparation process shown in Figure 9.

[0042] Moreover, the bulge portion 94 of the intermediate molded product 91 of this embodiment is drawn deeper than the bulge portion 94 of the intermediate molded product 91 of the first embodiment, and a larger amount of material of the side wall 93 flows toward the bottom wall 92. The depth of the bulge portion 94 is appropriately selected depending on, for example, the thickness of the side wall 93 relative to the size of the planar cross section of the intermediate molded product 91 and the hardness of the material of the intermediate molded product 91. The bulge portion 94 can be made deeper by dividing the punching preparation step into multiple steps as in this embodiment.

[0043] Specifically, in the first punch preparation step, as shown in the change in shape from Fig. 7A to Fig. 7B, a bulging portion 94 and an annular inclined portion 97 that gradually narrows from a side wall 93 toward the bulging portion 94 are formed in a bottom wall 92 of an intermediate molded product 91. The inclination angle of the annular inclined portion 97 is 25° to 35° with respect to the pressing direction. In addition, the annular inclined portion 97 and the bulging portion 94 are at approximately the same height in the axial direction of the intermediate molded product 91.

[0044] In the second punching preparation step, as shown in the change in shape from Figure 7B to Figure 7C and the change in shape from Figure 8 to Figure 9, a part of the annular inclined portion 97 becomes part of the bulge portion 94, thereby extending the bulge portion 94 upward, and the remaining part of the annular inclined portion 97 forms the annular sheared portion 95.

[0045] 9, the inner and outer surfaces of the annular sheared portion 95 do not have, for example, the inner flat surface 95A and the outer flat surface 95B described in the first embodiment, and are formed only by corner curved surfaces 95R1 to 95R3. The entire inner corner curved surface 95R3 of the annular sheared portion 95 is disposed so as to overlap part of the outer corner curved surface 95R2 in the up-down direction.

[0046] The punch 21U, die 33, guide die 43 and counter punch 41 in the processing stage S for the first punching preparation step shown in FIG. 8 are configured as follows.

[0047] The guide die 43 is penetrated vertically by a work receiving hole 43Z into which the intermediate molded product 91 is fitted. The die 33 is formed with a forming hole 33Z coaxially with the work receiving hole 43Z. The forming hole 33Z is composed of a conical portion 33F and a straight portion 33G below the conical portion 33F. The conical portion 33F is a substantially quadrangular pyramid narrowing downward, and the inclination angle θ of the four inclined surfaces with respect to the pressing direction is, for example, 25° to 35° (preferably 30°). In addition, adjacent inclined surfaces are continuous with each other via a corner curved surface. Furthermore, the upper end opening of the conical portion 33F is slightly wider than the lower end opening of the work receiving hole 43Z.

[0048] The cross-sectional shape of the straight portion 33G is a rectangle similar to that of the work receiving hole 43Z, and all four inner faces of the straight portion 33G are flat faces substantially parallel to the pressing direction. The conical portion 33F and the straight portion 33G are connected by a corner curved surface 33R1.

[0049] The punch 21U is different from the punch 21 of the first embodiment only in that the distance between a pair of long sides of the rectangular cross-sectional shape of the punch extension 21Y is slightly larger and that all of the side surfaces of the punch extension 21Y are flat surfaces, and otherwise it is the same as the punch 21 of the first embodiment. That is, in the first punching preparation processing stage S, the distance between the surfaces of the four side surfaces of the punch extension 21Y and the four side surfaces of the opposing straight portion 33G that correspond to a pair of long sides of the rectangular cross-sectional shape is narrower than that of the punching preparation stage S of the first embodiment, so that a part of the bulging side wall 94A of the bulging portion 94 is squeezed as described later.

[0050] The counter punch 41 has a rectangular column shape that fits exactly into the straight portion 33G.

[0051] The punch 21V, die 31V and counter punch 41 in the processing stage S for the second punching preparation step shown in FIG. 9 are configured as follows.

[0052] The die 31V has substantially the same shape as the die 31 of the first embodiment, except that the step surface 31C of the forming hole 31Z is narrow and all four side surfaces 31D below the step surface 31C are flat. The planar cross-sectional shape of the portion of the die 31V having the side surfaces 31D is substantially the same as the planar shape of the straight portion 33G of the processing stage S for the first punching preparation step.

[0053] The punch 21V has substantially the same shape as the punch 21U of the processing stage S for the first punching preparation step.

[0054] The counter punch 41 has a rectangular column shape that fits exactly inside the side surface 31D of the forming hole 31Z.

[0055] The configuration of the transfer press 10 of this embodiment and the method for manufacturing the tubular product 90 are as described above. The effects of this embodiment will be described below.

[0056] When the intermediate molded product 91 is pushed into the work receiving hole 43Z and the molding hole 33Z by the punch 21U of the processing stage S for the first punch preparation step shown in FIG. 8, the corner curved surface 93R (see FIG. 7A) of the outer edge of the lower end of the intermediate molded product 91 abuts against the conical portion 33F of the molding hole 33Z. The punch 21U continues to descend from there, and the annular inclined portion 97 is formed from a part of the bottom wall 92. Then, even after the lower end of the bottom wall 92 reaches the upper end of the straight portion 33G, the punch 21U continues to descend, and the bulging portion 94 is formed. At this time, a part of the annular inclined portion 97 is drawn into the straight portion 33G to become the bulging portion 94, and the side wall 93 of the intermediate molded product 91 is drawn in and becomes a part of the annular inclined portion 97. Then, due to this drawing in of the side wall 93, the annular recess 93S described in the first embodiment moves toward the bottom wall 92. At this time, the portions of the bulging side wall 94A of the bulging portion 94 that correspond to a pair of long sides of the rectangular cross section are squeezed, and the material of those portions flows upward from the bulging portion 94. As a result, the wall thickness of the pair of long sides of the rectangular cross section of the bulging portion 94 becomes thinner than the wall thickness of the pair of short sides.

[0057] The intermediate molded product 91 that has completed the first punch preparation step is transported by the transfer device 11 to the processing stage S for the second punch preparation step. When the intermediate molded product 91 is pressed into the molding hole 31Z in the processing stage S for the second punch preparation step, the annular inclined portion 97 comes into contact with the corner curved surface 31R1 of the die 31V. As the punch 21V continues to descend from there, the lower portion of the annular inclined portion 97 is raised so as to be parallel to the pressing direction, and the bulging portion 94 is thereby extended upward.

[0058] Simultaneously with the upward extension of the bulging portion 94, the upper portion of the annular inclined portion 97 is pressed against the corner curved surface 21R1 of the punch body 21X and then against the corner curved surface 31R1 of the die 31V to form the annular sheared portion 95.

[0059] After the second punching preparation step, the intermediate product 91 is subjected to the punching step processing stage S, in the same manner as in the first embodiment, where the annular sheared portion 95 is sheared and the bottom wall 92 is punched out, thereby forming a cylindrical product 90.

[0060] In the transfer press 10 and the manufacturing method of the cylindrical product 90 of the present embodiment, as in the first embodiment, the bulge 94 is formed on the bottom wall 92 before being punched out from the intermediate product 91, so that the fluidity of the material between the side wall 93 and the bottom wall 92 of the intermediate product 91 is increased, and the wall thickness of the side wall 93 of the intermediate product 91 is made uniform, and a cylindrical product 90 with higher shape quality than the conventional one can be manufactured. In addition, when the bulge 94 is shallow and the wall thickness cannot be sufficiently uniformed, the bulge 94 can be formed deep by dividing the punch preparation process into multiple times as in the present embodiment, and the wall thickness can be sufficiently uniformed. In addition, when the bulge 94 is made deep, a phenomenon may occur in which a part of the material of the side wall 93 flows too far toward the bottom wall 92. Specifically, when the bulge 94 is shallow, a pair of long sides have excess material, and when the bulge 94 is deep, the material flows out too far. In contrast, in the present embodiment, by squeezing a portion of the bulging side wall 94A of the bulging portion 94, excessive outflow of meat can be suppressed, which also makes it possible to sufficiently uniform the wall thickness, thereby improving the shape quality of the tubular product 90. [Other embodiments]

[0061] In the first and second embodiments, the bottom wall 92 of the intermediate molded product 91 is rectangular, but may be any non-circular shape, such as a square, a polygon other than a rectangle, an ellipse, an oval, or an irregular shape without a name.

[0062] In the first and second embodiments, the planar cross-sectional shape of the side wall 93 of the intermediate molded product 91 is uniform in the vertical direction, but the shape or size of the planar cross-section may vary depending on the vertical position of the side wall 93. For example, the lower end of the side wall 93 may be non-circular like the bottom wall 92, but may have a shape that gradually changes to a circular shape as it moves away from the lower end, or may have a step part midway, with the side below the step part having the same planar cross-sectional shape as the bottom wall 92 and the side above the step part having a planar cross-sectional shape different from that of the lower side.

[0063] In the first embodiment, only two of the four faces of the bulging side wall 94A of the bulging portion 94, which correspond to a pair of long sides, were curved, but all of the multiple faces of the bulging side wall 94A may be curved away from the outer edge portion depending on the amount of excess material in the side wall 93.

[0064] In the second embodiment, only two of the four faces of the bulging side wall 94A of the bulging portion 94, which correspond to a pair of long sides, are squeezed to cause the meat to flow upward, but depending on the level of meat shortage in the side wall 93, all of the multiple faces of the bulging side wall 94A may be squeezed to cause the meat to flow upward.

[0065] In the second embodiment, the bulging side wall 94A is squeezed only in the first punch preparation step out of the first and second punch preparation steps, but the bulging side wall 94A may be squeezed only in the second punch preparation step or in both the first and second punch preparation steps.

[0066] In the second embodiment, the punch preparation step is performed in two separate steps, but it may be performed in three or more separate steps.

[0067] In the first and second embodiments, the inclined surface 93A is formed at the lower end of the side wall 93 of the intermediate molded product 91, but the inclined surface 93A does not necessarily have to be formed.

[0068] <Additional Notes> The following describes the feature groups extracted from the above-described embodiments, while indicating their effects, etc., as necessary. For ease of understanding, the corresponding configurations in the above-described embodiments are appropriately indicated in parentheses, but these feature groups are not limited to the specific configurations indicated in parentheses.

[0069] [Feature 1] The method for producing a tubular product (90) includes a punching preparation step in which the bottom wall (92) is press-formed into a shape having an annular sheared portion (95) having inner and outer surfaces intersecting a pressing direction and a bulge portion (94) surrounded by the annular sheared portion (95), and a punching step in which the annular sheared portion (95) is sheared to punch out the bottom wall (92).

[0070] [Feature 2] The intermediate molded product (91) is produced through a plurality of press moldings before the punching preparation step, and an annular recess (93S) is formed on the inner surface of the side wall (93) of the intermediate molded product (91) facing the bottom wall (92) during the press molding. In the punching preparation step, the material of a portion of the side wall (93) having the annular recess (93S) is moved toward the bottom wall (92), or the material above the annular recess (93S) is moved toward the annular recess (93S).

[0071] [Feature 3] A manufacturing method for a tubular product (90) according to feature 1 or 2, in which the planar shapes of the bottom wall (92) and the bulge portion (94) are polygonal and substantially similar to each other, and the bulge portion (94) is press-molded so that at least a portion of the multiple sides of the polygon that is the planar shape of the bulge portion (94) are curved away from the side corresponding to the polygon that is the planar shape of the bottom wall (92).

[0072] [Feature 4] A manufacturing method for a tubular product (90) according to feature 3, wherein the polygon is a quadrangle having a pair of short sides and a pair of long sides, and the bulge (94) is press-molded so that only the pair of long sides are curved away from the side corresponding to the bottom wall (92).

[0073] [Feature 5] 5. The method for producing a tubular product (90) according to any one of features 1 to 4, wherein the bulge (94) and the annular sheared portion (95) are formed by a single press.

[0074] [Feature 6] The method for manufacturing a tubular product (90) according to any one of features 1 to 4, wherein the punching preparation step includes a first punching preparation step in which the bottom wall (92) is press-molded with the bulge (94) and an annular inclined portion (97) that gradually narrows from the side wall (93) of the intermediate molded product (91) toward the bulge (94), and a second punching preparation step in which a portion of the annular inclined portion (97) that is to become the bulge (94) is bent toward a side parallel to the press direction to become part of the bulge (94), and a remaining portion of the annular inclined portion (97) is bent toward a side perpendicular to the press direction to become the annular sheared portion (95).

[0075] [Feature 7] 7. The method for producing a tubular product (90) according to claim 6, wherein the inclination angle of the annular inclined portion (97) with respect to the pressing direction is 25° to 35°.

[0076] [Feature 8] The method for manufacturing a tubular product (90) according to feature 6, wherein the planar shapes of the bottom wall (92) and the bulge portion (94) are polygonal and substantially similar to each other, and in the first or second punching preparation step, a bulge side wall (94A) corresponding to at least a part of the sides of the polygon that is the planar shape of the bulge portion (94) is ironed.

[0077] [Feature 9] A manufacturing method for a cylindrical product (90) according to any one of features 1 to 8, wherein a cylindrical body forming process in which a flat plate is drawn multiple times to form the intermediate formed product (91), the punching preparation process, and the punching process are performed in a common transfer press machine (10).

[0078] [Feature 10] A transfer press machine (10) having a plurality of processing stages (S) arranged in a row in the horizontal direction, in which a workpiece is moved sequentially to one side in the horizontal direction and processed in each of the processing stages (S), the plurality of processing stages (S) including a plurality of processing stages (S) for a cylindrical body forming process in which a flat plate is squeezed multiple times to form a cylindrical intermediate formed product (91) having a non-circular bottom wall (92), one or more processing stages (S) for a punching preparation process in which the bottom wall (92) of the intermediate formed product (91) is formed into a shape having an annular sheared portion (95) having inner and outer surfaces intersecting a press direction and a bulge portion (94) surrounded by the annular sheared portion (95), and a processing stage (S) for a punching process in which the annular sheared portion (95) is sheared to punch out the bottom wall (92).

[0079] [Feature 11] A transfer press (10) according to feature 10, wherein, in the processing stages (S) for the plurality of cylindrical molding processes, the intermediate molded product (91) is squeezed until an annular recess (93S) is formed on the inner surface of the end of the side wall (93), and, in the processing stages (S) for the one or more punching preparation processes, material of a portion of the side wall (93) having the annular recess (93S) is caused to flow toward the bottom wall (92), or material above the annular recess (93S) is caused to flow toward the annular recess (93S).

[0080] [Feature 12] The transfer press machine (10) according to feature 10 or 11, wherein in the multiple processing stages (S), the bottom wall (92) of the intermediate molded product (91) is formed into a polygon, and in the one or more processing stages (S) for the punching preparation process, the planar shape of the bulge portion (94) is formed into a polygon that is approximately similar to the bottom wall (92) of the intermediate molded product (91) and has at least a portion of its sides curved away from the side of the bottom wall (92) corresponding to the polygon.

[0081] [Feature 13] The transfer press (10) according to feature 12, wherein the polygon is a rectangle having a pair of short sides and a pair of long sides, and the bulge (94) is formed so that only the pair of long sides are curved away from the side corresponding to the bottom wall (92). [Feature 14] A transfer press machine (10) according to any one of features 10 to 13, in which the number of processing stages (S) for the punching preparation process is one, and the bulge portion (94) and the annular sheared portion (95) are formed in a single press.

[0082] [Feature 15] 14. The transfer press (10) according to any one of Features 10 to 13, wherein a plurality of processing stages (S) for the punching preparation process are provided, and the plurality of processing stages (S) for the punching preparation process include one or more processing stages (S) for a first preparation stage that forms, in the bottom wall (92), the bulge (94) and an annular inclined portion (97) that gradually narrows from a side wall (93) of the intermediate molded product (91) toward the bulge (94), and one or more processing stages (S) for a second preparation stage that bends a portion of the annular inclined portion (97) that is to become the bulge (94) toward a side parallel to the press direction to form it as part of the bulge (94), and bends a remaining portion of the annular inclined portion (97) toward a side perpendicular to the press direction to form the annular sheared portion (95).

[0083] [Feature 16] 16. The method for producing a tubular product (90) according to claim 15, wherein the inclination angle of the annular inclined portion (97) with respect to the pressing direction is 25° to 35°.

[0084] [Feature 17] The transfer press machine (10) according to feature 15 or 16, wherein the bottom wall (92) and the bulge portion (94) of the intermediate molded product (91) are molded so that their planar shapes are polygonal and roughly similar to each other, and in the processing stage (S) for the first or second punching preparation step, a bulge side wall (94A) corresponding to at least a part of the sides of the polygon that is the planar shape of the bulge portion (94) is squeezed.

[0085] The above group of features provides the following effects. That is, when the bottom wall of the intermediate product, which is a press-molded product, is non-circular, it is difficult for the flow of material to be uniform between the side wall and the bottom wall during press molding, and differences in wall thickness of the side wall are likely to occur. However, in the manufacturing method and transfer press machine of features 1 and 10, a bulge is formed on the bottom wall before it is punched out of the intermediate product, so that the excess material of the bottom wall is absorbed by the bulge. This increases the fluidity of the material between the side wall and the bottom wall of the intermediate product, and the wall thickness of the side wall of the intermediate product is made uniform. Then, the annular sheared portion of the bottom wall around the bulge is sheared and the bottom wall is punched out to form a cylindrical product, so that the uniformity of the wall thickness of the side wall of the cylindrical product is improved compared to the conventional method. That is, according to the first and second aspects of the present disclosure, a cylindrical product with higher shape quality than the conventional method can be manufactured.

[0086] When a cylindrical intermediate product is formed by multiple press moldings, a ring-shaped recess (so-called shock mark) may be formed on the inner surface of the bottom wall side of the side wall of the intermediate product due to the press molding. In contrast, when the above-mentioned bulge is formed and the fluidity of the material increases, the material in the part having the ring-shaped recess flows to the bottom wall side, or the material above the ring-shaped recess flows to the ring-shaped recess, so that the ring-shaped recess does not remain in the cylindrical product, and the shape quality is improved (Features 2, 11).

[0087] When the bottom wall of the intermediate product is polygonal, the meat may gather in a large amount at the center of at least some of the side walls on the bottom wall side of the intermediate product. In contrast, in features 3 and 12, the bulge is press-molded so that the planar shape of the bulge is a polygon similar to the bottom wall, and at least some of the sides of the polygon are curved away from the outer edge of the bottom wall. This makes it possible to curve the bulge away from the outer edge of the bottom wall in the part where the meat tends to gather in a large amount, making it easier for the meat in the center of the side wall of the intermediate product to flow toward the bottom wall, thereby making the wall thickness of the side wall of the intermediate product uniform. In addition, as in features 4 and 13, when the polygon is a rectangle having a pair of short sides and a pair of long sides, the meat tends to gather in the center of the side wall corresponding to the pair of long sides, so that only the parts of the bulge that correspond to the pair of long sides are curved away from the outer edge of the bottom wall, making the wall thickness of the side wall of the intermediate product uniform.

[0088] The bulging portion and the annular sheared portion may be formed in one press as in Features 5 and 14, or the bulging portion and the annular inclined portion gradually tapering toward the bulging portion may be press-formed on the bottom wall first as in Features 6 and 15, and then a part of the annular inclined portion may be bent to the side perpendicular to the pressing direction to form the annular sheared portion. In this case, as in Features 7 and 16, by setting the inclination angle of the annular inclined portion with respect to the pressing direction to, for example, 25° to 35°, the meat can flow smoothly toward the bulging portion.

[0089] When the bottom wall of the intermediate product is polygonal, the material of at least some of the side walls of the intermediate product may flow too much from the center toward the bulge, resulting in thinning. In contrast, in Features 8 and 17, the side of at least some of the bulges is squeezed, thereby suppressing the material flow toward the bulge, and making the wall thickness of the side walls of the intermediate product uniform.

[0090] According to the ninth feature, by using a transfer press, it is possible to simultaneously manufacture an intermediate product and manufacture a cylindrical product from the intermediate product.

[0091] In addition, although this specification and drawings disclose specific examples of the technology included in the scope of the claims, the technology described in the claims is not limited to these specific examples, but includes various modifications and variations of the specific examples, as well as parts of the specific examples taken alone. [Explanation of symbols]

[0092] 10 Transfer press machine 90 Cylindrical products 91 Intermediate molded products 92 Bottom wall 93 Side wall 93S Annular recess 94 Bulge 95 Annular sheared part 97 Circular inclined section S Processing stage θ Tilt angle

Claims

1. A manufacturing method for manufacturing a cylindrical product by punching out a bottom wall from an intermediate product which is a cylindrical press-molded product having a non-circular bottom wall, comprising: a punching preparation process in which the bottom wall is press-formed into a shape having an annular sheared portion having inner and outer surfaces intersecting a pressing direction and a bulge portion surrounded by the annular sheared portion; a punching step in which the annular sheared portion is sheared to punch out the bottom wall; was carried out, The intermediate product is produced through a plurality of press moldings before the punching preparation step, and an annular recess is formed on an inner surface of a bottom wall side of a side wall of the intermediate product by the press moldings, A method for manufacturing a tubular product, wherein in the punching preparation process, the material of a portion of the side wall having the annular recess is moved toward the bottom wall, or the material above the annular recess is moved toward the annular recess.

2. A manufacturing method for manufacturing a cylindrical product by punching out a bottom wall from an intermediate product which is a cylindrical press-molded product having a non-circular bottom wall, a punching preparation process in which the bottom wall is press-formed into a shape having an annular sheared portion having inner and outer surfaces intersecting a pressing direction and a bulge portion surrounded by the annular sheared portion; a punching step in which the annular sheared portion is sheared to punch out the bottom wall; was carried out, The bottom wall and the bulge have planar shapes that are substantially similar to each other in polygonal form, A manufacturing method for a tubular product in which the bulge is press-molded so that at least some of the multiple sides of the polygon that forms the planar shape of the bulge are curved away from the side corresponding to the polygon that forms the planar shape of the bottom wall.

3. A method for manufacturing a cylindrical product as described in claim 2, wherein the polygon is a quadrilateral having a pair of short sides and a pair of long sides, and the bulge portion is press-molded so that only the pair of long sides are curved away from the side corresponding to the bottom wall.

4. A method for manufacturing a cylindrical product described in any one of claims 1 to 3, wherein the bulge portion and the annular sheared portion are formed in a single press.

5. A manufacturing method for manufacturing a cylindrical product by punching out a bottom wall from an intermediate molded product which is a cylindrical press molded product having a non-circular bottom wall, a punching preparation process in which the bottom wall is press-formed into a shape having an annular sheared portion having inner and outer surfaces intersecting a pressing direction and a bulge portion surrounded by the annular sheared portion; a punching step in which the annular sheared portion is sheared to punch out the bottom wall; was carried out, The punching preparation step includes: a first punching preparation step in which the bottom wall is press-formed with the bulge and an annular inclined portion that gradually narrows from a side wall of the intermediate molded product toward the bulge; a second punching preparation process in which a portion of the annular inclined portion that will become the bulge portion is bent parallel to the press direction to become part of the bulge portion, and a remaining portion of the annular inclined portion is bent perpendicular to the press direction to become the annular sheared portion.

6. A method for manufacturing a cylindrical product as described in Claim 5, wherein the inclination angle of the annular inclined portion relative to the press direction is 25° to 35°.

7. The planar shapes of the bottom wall and the bulge portion are polygons that are approximately similar to each other, 6. The method for manufacturing a cylindrical product according to claim 5, wherein in the first or second punch preparation step, a bulging side wall corresponding to at least a part of the sides of the polygonal planar shape of the bulging portion is ironed.

8. A method for manufacturing a cylindrical product as described in any one of claims 1, 2 or 5, wherein a cylindrical molding process in which a flat plate is squeezed multiple times to form the intermediate molded product, the punching preparation process, and the punching process are carried out using a common transfer press machine.

9. A transfer press machine having a plurality of machining stages arranged in a row in a horizontal direction, in which a workpiece is moved sequentially to one side in the horizontal direction and machined at each of the machining stages, The plurality of processing stages include: a plurality of processing stages for a cylindrical body forming step in which a flat plate is drawn a plurality of times to form a cylindrical intermediate product having a non-circular bottom wall; one or more processing stages for a punching preparation step for forming the bottom wall of the intermediate molded product into a shape having an annular sheared portion having inner and outer surfaces intersecting with a pressing direction and a bulge portion surrounded by the annular sheared portion; a processing stage for a punching step of shearing the annular sheared portion to punch out the bottom wall, In the processing stages for the plurality of cylindrical body forming steps, the intermediate formed product is squeezed until an annular recess is formed on the inner surface of the end of the side wall thereof; A transfer press machine that, in the processing stage for the one or more punching preparation steps, causes the material of the portion of the side wall having the annular recess to flow toward the bottom wall, or causes the material above the annular recess to flow toward the annular recess.

10. A transfer press machine having a plurality of machining stages arranged in a row in a horizontal direction, in which a workpiece is moved sequentially to one side in the horizontal direction and machined at each of the machining stages, The plurality of processing stages include: a plurality of processing stages for a cylindrical body forming step in which a flat plate is drawn a plurality of times to form a cylindrical intermediate product having a non-circular bottom wall; one or more processing stages for a punching preparation step for forming the bottom wall of the intermediate molded product into a shape having an annular sheared portion having inner and outer surfaces intersecting with a pressing direction and a bulge portion surrounded by the annular sheared portion; a processing stage for a punching step of shearing the annular sheared portion to punch out the bottom wall, In the plurality of processing stages, the bottom wall of the intermediate molded product is molded into a polygonal shape; In the processing stage for the one or more punching preparation steps, a transfer press machine shapes the planar shape of the bulge portion into a polygon that is roughly similar to the bottom wall of the intermediate molded product and has at least some of its sides curved away from the side of the bottom wall corresponding to the polygon.

11. A transfer press machine as described in claim 10, wherein the polygon is a rectangle having a pair of short sides and a pair of long sides, and the bulge is formed so that only the pair of long sides curve away from the side corresponding to the bottom wall.

12. The number of processing stages for the punching preparation process is 1, 12. A transfer press according to claim 9, wherein the bulging portion and the annular sheared portion are formed in a single press operation.

13. A transfer press machine having a plurality of machining stages arranged in a row in a horizontal direction, in which a workpiece is moved sequentially to one side in the horizontal direction and machined at each of the machining stages, The plurality of processing stages include: a plurality of processing stages for a cylindrical body forming step in which a flat plate is drawn a plurality of times to form a cylindrical intermediate product having a non-circular bottom wall; one or more processing stages for a punching preparation step for forming the bottom wall of the intermediate molded product into a shape having an annular sheared portion having inner and outer surfaces intersecting with a pressing direction and a bulge portion surrounded by the annular sheared portion; a processing stage for a punching step of shearing the annular sheared portion to punch out the bottom wall, A plurality of processing stages for the punching preparation process are provided, The processing stages for these multiple punch preparation processes include: one or more processing stages for a first preparation stage for forming the bulge and an annular inclined portion that gradually narrows from a side wall of the intermediate molded product toward the bulge on the bottom wall; a second preparation stage or stages for bending a portion of the annular inclined portion that is to become the bulge portion in a direction parallel to the press direction to form it into part of the bulge portion, and bending a remaining portion of the annular inclined portion in a direction perpendicular to the press direction to form it into the annular sheared portion.

14. A method for manufacturing a cylindrical product as described in Claim 13, wherein the inclination angle of the annular inclined portion relative to the press direction is 25° to 35°.

15. The bottom wall and the bulge portion of the intermediate molded product are molded to have polygonal shapes that are approximately similar to each other in plan view, 14. The transfer press according to claim 13, wherein a bulging side wall corresponding to at least a part of the sides of the polygonal planar shape of the bulging portion is squeezed in the processing stage for the first or second punch preparation step.

Images