Knockout structure and method for bottomed cylindrical products

Abstract

This invention improves upon the occurrence of partial buckling and localized deformation in thin, bottomed, cylindrical metal products during knockout. [Solution] The knockout structure for the bottomed cylindrical product of the present invention is configured such that, in the extruder 1, the die 2 and the lower punch 4 (the other punch) located inside the bottomed cylindrical product P can move relative to each other after molding, and air can be injected from the surface of the lower punch 4 located inside the bottomed cylindrical product P that is in contact with the inner bottom surface of the product P. [Effect] The knockout pin equivalent configuration can be eliminated, and because the knockout pin equivalent configuration has been eliminated, when knocking out a thin, bottomed cylindrical metal product, partial buckling and local deformation of the product are suppressed.

Description

Technical Field

[0001] The present invention relates to a knockout structure and method for a bottomed cylindrical product made of thin metal, which can be knocked out without causing partial buckling or local deformation.

Background Art

[0002] The process of removing the workpiece from the die after forming is called knockout. For example, in press working, it is a process of separating the product formed between the punch and the die, simply speaking, from the die or the punch. Knockout is configured to physically move the formed product from the forming space by the punch and the die, for example, by pushing it out of the forming space by a member (mechanism) called a knockout pin. Regarding such knockout structures (methods), for example, Patent Documents 1 and 2 are known.

[0003] In Patent Document 1 (Japanese Patent Laid-Open No. 2-247036), for the purpose of reducing the buckling load of the punch on the side where the metal material is extruded and extending the forming length of the formed cylindrical body, a die having a cylindrical inner surface is movably arranged with respect to a receiving member that receives a solid cylindrical blank, and it is proposed to move the die in the direction of the pushing punch during pushing by the relative approaching movement of the pushing punch and the receiving member.

[0004] Patent Document 2 (Japanese Patent Publication No. 2001-321877) proposes a knockout pin with the aim of ensuring a sufficient knockout stroke and allowing easy adjustment of the knockout stroke amount. This involves providing a guide member that guides the intermediate portion of the knockout pin and is movable forward and backward along a guide hole, the guide member having an engagement / disengagement mechanism that can engage with the knockout pin, and the base end of the knockout pin having a pressing portion that presses the guide member back to its original position once it has advanced a predetermined stroke. The engagement / disengagement mechanism is designed so that when the knockout pin advances, the engagement is disengaged, separating the knockout pin and the guide member; when the knockout pin retracts, the engagement is engaged, causing the knockout pin and the guide member to move in conjunction; and when the guide member returns to its original position, the engagement is disengaged, separating them again.

[0005] Incidentally, in recent years, electrification has progressed in various fields, and the demand for batteries (including so-called rechargeable batteries) as a power source has increased. Batteries are constructed by loading contents into a metal, bottomed cylindrical container, and then attaching a lid. This type of bottomed cylindrical container needs to be as thin as possible not only to maintain the quality of the molded product, but also to maximize the efficiency of loading the battery contents.

[0006] When obtaining thin metal products, such as the bottomed cylindrical containers for batteries mentioned above, by extrusion molding, there is frictional resistance between the metal material sandwiched between the inside of the die and the outside of the punch. Combined with the thinness of the molded product, conventional knockout structures and methods using knockout pin equivalent configurations could cause the product to partially buckle or locally deform. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2008-180558 [Patent Document 2] Japanese Patent Publication No. 2019-158899 [Overview of the project] [Problems that the invention aims to solve]

[0008] The problem that this invention aims to solve is that, in conventional knockout structures and methods for molded products, when knocking out a thin, bottomed cylindrical metal product, the product experiences partial buckling or localized deformation. [Means for solving the problem]

[0009] To solve the above problems, the knockout structure for a bottomed cylindrical product of the present invention is a knockout structure for removing a bottomed cylindrical product after it has been formed from an extrusion device comprising a die, a punch for pushing a metal material into the die, and a punch for coaxial linear movement opposite the extrusion surface of the punch for forming a bottomed cylindrical product from a metal material. The knockout structure allows either the die or the punch for coaxial linear movement located inside the bottomed cylindrical product to move relative to the bearing portion, which is a forming space formed by the inside of the die and the outside of the punch for coaxial linear movement located inside the bottomed cylindrical product, and also allows air to be injected from the surface of the punch for coaxial linear movement located inside the bottomed cylindrical product that is in contact with the inner bottom surface of the bottomed cylindrical product. [Effects of the Invention]

[0010] According to the present invention, since it does not locally contact and push out the molded product like a knockout pin, it has the advantage of not causing localized buckling or localized deformation. [Brief explanation of the drawing]

[0011] [Figure 1] Figures (a) to (e) illustrate the knockout situation when the present invention is used in an extrusion apparatus that forms bottomed cylindrical products by forward extrusion. [Figure 2]This figure illustrates a knockout structure when a modified version of the present invention is applied to an extrusion apparatus that forms a bottomed cylindrical product by forward extrusion. [Figure 3] Figures (a) to (d) illustrate the knockout situation when a modified version of the present invention is applied to an extrusion apparatus that forms a bottomed cylindrical product with excess material by forward extrusion. [Figure 4] Figures (a) to (d) illustrate the knockout situation when a modified version of the present invention is used in an extrusion apparatus that forms a bottomed cylindrical product by backward extrusion. [Figure 5] This is a diagram illustrating the knockout method in a conventional forward extrusion apparatus. [Modes for carrying out the invention]

[0012] The present invention relates to an extrusion apparatus for forming a cylindrical bottomed product from a metal material, which improves upon the occurrence of partial buckling or local deformation in the product when knocking out a thin, bottomed cylindrical metal product. The apparatus comprises a die, a punch for pushing the metal material into the die, and a punch that is coaxially linearly movable opposite the extrusion surface of the punch. The present invention provides a configuration that allows the die, the punch located inside the cylindrical bottomed product, or the other punch to be moved relative to the die after forming, in order to release the clamped state of the metal material in the bearing portion, which is a forming space formed by the inside of the die and the outside of the punch located inside the cylindrical bottomed product. Furthermore, the apparatus is configured to allow air to be injected from the surface of the punch located inside the cylindrical bottomed product that is in contact with the inner bottom surface of the cylindrical bottomed product.

[0013] Figure 5 shows a schematic partial configuration of the extrusion apparatus 1. The extrusion apparatus 1 in Figure 5 performs forward extrusion molding. The extrusion apparatus 1 comprises a die 2, an upper punch 3 (one-sided punch) for press-feeding the metal material into the die 2, and a lower punch 4 that is mounted to move linearly along the same axis, facing the extrusion surface of the upper punch 3.

[0014] For example, when a bottomed cylindrical product is extruded forward from a metal material and then removed from the molded space by a knockout punch 5 inserted into the molded space, depending on the type of metal material, the thickness and height (depth) of the product P, the frictional force (resistance) between the inner surface of the die 2 and the outer surface of the product P, and between the outer surface of the lower punch 4 and the inner surface of the product P may be greater than the force required to push out the product P by the knockout punch 5. In such cases, even if the knockout punch 5 is operated, the product P will not be pushed out, and as a result, the open end of the product P will buckle.

[0015] The buckling described above is caused by the frictional force (resistance) between the inner surface of the die 2 and the outer surface of the product P, and between the outer surface of the lower punch 4 and the inner surface of the product P, as well as the knockout punch 5. Therefore, in the present invention, a structure is adopted to reduce the frictional force (resistance) between the inner surface of the die 2 and the outer surface of the product P, and between the outer surface of the lower punch 4 and the inner surface of the product P. In addition, the knockout pin equivalent configuration that locally contacts the knockout punch 5 and pushes the product P is removed, and instead a structure is adopted in which the product P is removed by, for example, a low-pressure air jet.

[0016] The following explanation will be given with reference to Figures 1 to 4. Note that in Figures 1 to 4, the same (equivalent) components as in Figure 5 are given the same component names and reference numerals. Figures 1 to 3 show the so-called forward extrusion molding configuration of the extrusion apparatus 1, and Figure 4 shows the so-called backward extrusion molding configuration. In Figures 1 to 4, the flow path of the metal material is narrowed by the bearing portion 2A formed at a point midway along the press-fitting direction on the inner surface of the die 2 and the bearing portion 4A formed on the circumferential surface of the press-fitting end of the metal material by the lower punch 4, and the frictional resistance between the metal material and the die 2 and lower punch 4 remains large when extruding the product P.

[0017] In the forward extrusion examples shown in FIGS. 1 to 3, in order to release the clamping state of the product P in the bearing portions 2A and 4A during knockout, the "lower punch 4" is moved to the upper punch 3 side with respect to the bearing portion 2A on the die 2 side in the order shown in FIGS. 1(a)-(b)-(c), or the "die 2" is moved to the upper punch 3 side with respect to the bearing portion 4A on the lower punch 4 side in the order shown in FIGS. 1(a)-(d)-(e), that is, a configuration is adopted in which one is relatively moved with respect to the other.

[0018] In this example, for example, the structure is such that the "lower punch 4" shown in FIGS. 1(a)-(b)-(c) is moved to the upper punch 3 side with respect to the bearing portion 2A on the die 2 side. The reason is that to make the die 2 have a moving structure, it is necessary to modify the overall structure of the extrusion device 1, but if the structure is such that the lower punch 4 is moved to the upper punch 3 side with respect to the bearing portion 2A on the die 2 side, it can be dealt with only by control because the lower punch 4 is originally configured to move.

[0019] Also, in this example, as shown in FIG. 2, the inner side of the die 2 that forms the bearing portions 2A and 4A, the outer side of the lower punch 4 located inside the bottomed cylindrical product P, and further, for example, both ends in the extrusion direction on the inner side of the die 2 and the outer side of the lower punch 4 are subjected to R chamfering. By doing so, the clamping state of the product P in the bearing portion can be released and the frictional resistance can be reduced.

[0020] In addition, in the case of the structure in the order of FIGS. 1(a)-(b)-(c), that is, the "lower punch 4" is moved to the upper punch 3 side with respect to the bearing portion 2A on the die 2 side, when the lower punch 4 is moved to the upper punch 3 side, the upper punch 3 is brought into contact with the outer side of the bottom surface of the product P and a suitable back pressure is applied so that the (metal) material does not break, especially at the corners or edges of the bottom of the product P. By doing so, it is possible to suppress the occurrence of breakage even if the thickness of the product P is further reduced.

[0021] Moreover, the present invention does not have a knockout punch or a structure equivalent to a knockout pin as described above. The knockout pin is used to take out the molded product P from the die 2 by locally contacting and pressing a part of the product P. However, when locally contacting and pressing in this case, in the case of the bottomed cylindrical product P with a thin thickness, due to the above-mentioned frictional resistance, it may be difficult to take out in some cases, and moreover, the portion pressed by the structure equivalent to the knockout pin may be deformed.

[0022] Instead of deleting the structure equivalent to the knockout pin, in the present invention, it has a structure in which air can be injected from the surface of the lower punch 4 (the other punch) in this example, which is located inside the bottomed cylindrical product, and contacts the inner bottom surface of the bottomed cylindrical product P. In the extrusion device 1 shown in FIG. 1, air is injected from the injection portion 6 formed on the lower punch 4 (the other punch) toward the inner bottom surface of the product P.

[0023] By doing so, air fills between the inner bottom portion of the bottomed cylindrical product P and the end surface of the lower punch 4 in this example, the internal pressure increases, the entire inner bottom surface of the product P is uniformly pressed, and as a result, it can be lifted from the lower punch 4 and further taken out from the die 2.

[0024] What should be noted in the present invention is that, as described above, after releasing the clamping state of the product P in the bearing portions 2A and 4A to reduce the frictional resistance, the internal pressure between the inner bottom portion of the bottomed cylindrical product P and the end surface of the lower punch 4 in this example is increased to uniformly press the entire inner bottom surface of the product P. That is, it does not locally contact and press the product P like a knockout pin.

[0025] In short, the present invention deletes the structure equivalent to the knockout pin, releases the clamping state of the product P in the bearing portions 2A and 4A to reduce the frictional resistance, and also has a structure in which air is injected between the inner bottom portion of the product P and the end surface of the lower punch 4, thereby suppressing the buckling of the product P due to the structure equivalent to the knockout pin and also suppressing the local deformation of the product P.

[0026] Furthermore, the amount by which the lower punch 4 is moved toward the upper punch 3 relative to the bearing portion 2A on the die 2 side was set to the minimum amount necessary to release the product P from the gripping state in the bearing portions 2A and 4A as described above. However, considering the pickup (removal) of the product P after the release of the gripping state, it may be moved to a position where it leaves the inner space of the die 2, as described later.

[0027] For example, when forming a bottomed cylindrical product P, in order to ensure that the height of the open end of product P is uniform, the bottom surface of the metal material may be formed with an excess material α extending along the vertical side of product P that exceeds the lateral outer dimension of product P. If product P is formed from a metal material with excess material α, as described above, the height of the open end of product P will be uniform, which has the advantage of eliminating the need for the work of aligning the height of the open end.

[0028] When forming product P from a metal material having excess material α, as shown in Figure 3, the lower punch 4 can be moved in the order of Figure 3(a)-(b)-(d) to a position where it exits the inner space of die 2 toward the upper punch 3 relative to the bearing portion 2A on die 2, or the die 2 can be moved in the order of Figure 3(a)-(c)-(d) to a position where it exits the inner space of die 2 toward the upper punch 3 relative to the bearing portion 4A on the lower punch 4. This drastically reduces frictional resistance during knockout, allowing product P to be easily knocked out with a small amount of air injection.

[0029] In Figure 3, the bearing portions 2A and 4A shown in Figure 2 are formed on the inside of the die 2, and on the outside of the lower punch 4 located inside the bottomed cylindrical product P. In this example, the ends of both the inside of the die 2 and the outside of the lower punch 4 in the extrusion direction are also shown, with R-chamfering applied.

[0030] Furthermore, in the order shown in Figure 3(a)-(b)-(d), that is, in the structure in which the "lower punch 4" is moved toward the upper punch 3 side relative to the bearing portion 2A on the die 2 side, or in the order shown in Figure 3(a)-(c)-(d), that is, in the structure in which the "die 2" is moved toward the lower punch 4 side relative to the bearing portion 4A of the lower punch 4, in either case, the upper punch 3 may be brought into contact with the outside of the bottom surface of the product P, applying appropriate back pressure, so as not to cause fracture of the (metal) material, especially at the corners and edges of the bottom of the product P, while the lower punch 4 is moved.

[0031] In the example above, the extrusion device 1 was described as a forward extrusion device, but the present invention can also be applied to an extrusion device 1 for backward extrusion. In that case, as shown in Figure 4, the operation of the upper punch 3 (one punch) and the lower punch 4 (the other punch) will be in the opposite relationship to that in the example above.

[0032] Furthermore, in the example shown in Figure 4, for example, instead of the configuration of the spray unit 6 described above, a suction unit 7 is employed that uses negative pressure to suck the entire outer surface of the bottom surface of the product P, thereby releasing the contact between the surface of the upper punch 3, located inside the bottom cylindrical product, and the inner bottom surface of the product P, from the outside of the bottom surface of the product P.

[0033] For example, the bearing sections 2A and 3A are formed by the inner surface of the die 2 and the outer surface of the upper bunch 3 (one punch). To release the gripping state of the product P in these bearing sections 2A and 3A, either the "upper punch 3" is moved toward the lower punch 4 side relative to the bearing section 2A on the die 2 side in the order of Figure 4(a)-(b)-(d), or the "die 2" is moved toward the upper punch 3 side relative to the bearing section 3A on the upper punch 3 side in the order of Figure 4(a)-(c)-(d), meaning that one is moved relative to the other. Note that in this example, the movement of the upper punch 3 in Figure 4(b) and the die 2 in Figure 4(c) is limited to a position where they leave the inner space of the die 2, as shown in Figure 4(d).

[0034] Furthermore, in the case of rearward extrusion shown in Figure 4, if the injection unit 6 is used instead of the suction unit 7 as shown in Figures 1 to 3, the surface that contacts the inner bottom surface of the bottomed cylindrical product P is the upper punch 3, so the injection unit 6 from which air is injected will be provided on the upper punch 3. In addition, although not shown in Figure 4, if an R-chamfer configuration is adopted, it is sufficient if it is formed on the die 2 side (which is the same as above) and the upper punch 3 that constitute the bearings 2A and 3A. [Explanation of Symbols]

[0035] 1. Extruder 2 Dies 2A Bearing section 3. Upper punch (one-handed punch) 3A Bearing section 4. Lower punch (other punch) 4A Bearing section 6 Injection part 7 Adsorption part P product

Claims

1. A knockout structure for removing a formed cylindrical product from an extrusion apparatus comprising a die, a punch for pushing the metal material into the die, and a punch positioned opposite the extrusion surface of the punch and movable in a coaxial line, wherein the knockout structure for a cylindrical product is configured to release the pinched state of the metal material in the bearing portion, which is a forming space formed by the inside of the die and the outside of the punch positioned inside the cylindrical product, by allowing the die and the punch positioned inside the cylindrical product to move relative to each other after forming, and allowing air to be injected from the surface of the punch positioned inside the cylindrical product that is in contact with the inner bottom surface of the cylindrical product.

2. The knockout structure for a bottomed cylindrical product according to claim 1, wherein, instead of the configuration that allows air to be injected, the configuration is configured to release the contact between the surface of one or the other punch located inside the bottomed cylindrical product that is in contact with the inner bottom surface of the bottomed cylindrical product and the inner bottom surface of the bottomed cylindrical product, from the outside of the bottom surface of the bottomed cylindrical product.

3. The knockout structure for a bottomed cylindrical product according to claim 1 or 2, wherein the ends of either or both of the punches in the extrusion direction, located on the inside of the die forming the bearing portion and on the outside of one or the other punch located on the inside of the bottomed cylindrical product, are chamfered.

4. A knockout method for removing a formed cylindrical product from a metal material using an extrusion apparatus comprising a die, a punch for pushing the metal material into the die, and a punch positioned opposite the extrusion surface of the extrusion punch and capable of moving linearly along the same axis, the method comprising: moving the die and either the first or second punch located inside the cylindrical product relative to each other after forming to release the clamping state of the metal material in the bearing portion, which is a forming space formed by the inside of the die and the outside of the first or second punch located inside the cylindrical product; and then injecting air from the surface of the first or second punch located inside the cylindrical product that is in contact with the inner bottom surface of the cylindrical product.

5. The knockout method for a bottomed cylindrical product according to claim 4, wherein the relative movement of the die and either of the one or the other punch located inside the bottomed cylindrical product is performed until the die leaves the inner space.

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