JP4922037B2 - Aluminum alloy sheet press forming method and press forming apparatus - Google Patents

Description

  The present invention relates to a press forming method and a press forming apparatus for an aluminum alloy plate that can form a large-sized automobile member member (panel) that is difficult to form, such as an oil pan. Hereinafter, aluminum is also referred to as Al.

  As is well known, aluminum alloy panels are used in place of steel (steel plate) panels for automobile parts such as oil pans and member parts that form the skeleton of a vehicle body. These aluminum alloy panels are panel molded products (press molded products: simply referred to as panels hereinafter) in which aluminum alloy plates (blanks, panel molding material plates) are press-molded with a mold, as with steel plates. ing.

  Such automobile parts, such as oil pans, are particularly difficult to press-mold due to the recent diversification of automobile design. This is because the formability of the aluminum alloy plate is inferior to that of the steel plate and the shape of the oil pan itself.

  FIG. 4 is a perspective view showing a typical shape of the oil pan. As shown in FIG. 4, the oil pan 1 a has flat molding surfaces 2 and 3 at the upper part of the panel, and has a stepped portion (vertical wall portion) 4 in which the cross-sectional height of these molding surfaces 2 and 3 changes suddenly. Such a molded product panel. 5, 6 and 7 are surrounding vertical wall portions surrounding the planar molding surfaces 2 and 3, 5 is a side wall, 6 is a rear wall, and 7 is a front wall. The planar molding surface 8 surrounding the periphery is a flange or a surplus part.

  FIG. 5 is a perspective view showing a typical shape example of another automobile member part 1b. As shown in FIG. 5, the automobile member part 1 b has flat molding surfaces 2 and 3 at the upper part of the panel, and the cross-sectional heights of these molding surfaces 2 and 3 change suddenly in the same manner as the oil pan of FIG. 5. A step portion (vertical wall portion) 4 is provided. Here, the automobile member part 1b has a HAT cross-sectional shape, 6 and 7 are spaces (or may be a rear wall and a front wall), and 8 and 8 on both sides are flanges or surplus parts. is there.

  Automotive parts and automobile member parts having flat molding surfaces 2 and 3 at the upper part of the panel and having stepped portions 4 such that the sectional heights of these molding surfaces 2 and 3 change suddenly are made of aluminum alloy. When press-molding from a plate, wrinkles tend to occur on the molding surface of the molded product panel. Specifically, as shown in FIGS. 4 and 5, the wrinkle is formed as 9a on the molding surface (upper surface) 3 on the side having a low cross-sectional height, and as 9b on the surface (side surface) of the side wall 5. Prone to occur.

  Such wrinkles are caused by an oil pan 1a to an automobile member part 1b having a step part (vertical wall part) 4 in which the cross-sectional heights of the flat molding surfaces 2 and 3 are suddenly changed. This is a problem specific to molding with

  The wrinkles 9a generated on the molding surface 3 on the side having a low cross-sectional height are generated because the portion corresponding to the blank plate is freely deformed without contacting the punch to the vicinity of the bottom dead center. Further, the wrinkles 9b generated on the side wall surface (side surface) 5 have different side wall heights before and after the stepped portion 4, so that a difference also occurs in the material inflow amount due to molding, so as to eliminate the difference in the material inflow amount. It is a wrinkle that occurs. The problem that wrinkles 9a and 9b occur on both the molding surface (upper surface) 3 and the side wall surface (side surface) 5 is a problem peculiar to the molded product panel having a non-contact portion. That is, in such a panel molded product without the stepped portion 4, such a problem that wrinkles are generated on both the upper surface and the side surface hardly occurs.

  A normal method in the case where such an oil pan 1a is press-molded by a press apparatus will be described with reference to FIG. 8 which shows the state of the plate being pressed and the press apparatus. FIG. 8 is a cross-sectional view showing a deformed state of the aluminum alloy plate during pressing. Normally, the peripheral portion 31 (flange or surplus portion 8) of the aluminum alloy plate 30 is sandwiched between the die 22 and the blank holder (wrinkle pressing member) 20 and then fixed on the bolster (base) 21. The die 22 is relatively moved (lowered) toward the punch 11 to form the aluminum alloy plate 30.

  At this time, in the aluminum alloy plate 30 being formed, the portion corresponding to the flat forming surface 2 at the upper part of the panel of the oil pan 1a is 32, the portion corresponding to the forming surface 3 is 33, and the cross-sectional heights of these forming surfaces 2 and 3 are the same. A portion corresponding to the step portion (vertical wall portion) 4 that changes suddenly is 34. The portion corresponding to the rear wall 6 is 36, the portion corresponding to the front wall 7 is 37, the portion corresponding to the side wall 5 is 38 (punch equivalent portion 17c), and the portion corresponding to the flange or surplus portion 8 is the peripheral portion 31.

  As shown in FIG. 8, the length (distance) of the portion 33 not corresponding to the die 22 or the punch 11 is compared in the portion 33 corresponding to the panel forming surface 3 on the side having a low cross section of the aluminum alloy plate being formed. Become longer. That is, the length of the portion of the plate portion 33 that does not contact the die 22 or the punch 11 is determined from the point B that contacts the shoulder R portion of the molding surfaces 25 and 26 on the die 22 side to the length of the molding surface 13 on the punch 11 side. It becomes comparatively long to C point which contacts the shoulder R part. This is because the presence of the step 4 (corresponding portion 34) in the molded panel, that is, the sectional height of the step 4 is high and changes suddenly, so the molding surface 25 of the die 22 or the molding surface 14 of the punch 11 corresponding thereto. This is because the heights of these are high and these heights change suddenly.

  In such a case, the plate portion 33 (the portion corresponding to the molding surface 3) from the B point to the C point is freely deformed without contacting the punch 11 or the die 22 to the vicinity of the bottom dead center. For this reason, the plate portion 33 (the portion corresponding to the molding surface 3) from the B point to the C point is easily wrinkled due to inevitable non-uniform tension acting during molding. As a result, as shown in FIG. 4 and FIG. 5, wrinkles are likely to occur as 9a on the surface of the molding surface 3 on which the plate portion 33 is molded and the cross-sectional height is low. Further, as shown in FIG. 8, since the molding heights of the molding surfaces 2 and 3 are different before and after the step portion 4 (the difference in molding height occurs), the material from the flange portion to the punch portion during molding. There is also a difference in inflow. Therefore, in order to eliminate this difference in the amount of material inflow, wrinkles are likely to occur on the surface of the side wall 5 as 9b.

  As a countermeasure against this, a method of providing draw beads 61 and 62 on the blank holder 20 and applying a tension to the plate 30 is generally used, as shown in FIG. That is, a method is widely used in which the draw beads 61 and 62 are provided on the periphery of the plate 30 to prevent the occurrence of wrinkles by applying tension to the plate 30 from an early stage of press molding.

  In addition to this, when press-molding an aluminum alloy hood outer panel having a large bent portion at the end, it is expected that a recess that will cause wrinkles will be generated before or when wrinkle pressing starts. It has also been proposed to previously mold the center portion of the molding surface (see, for example, Patent Document 1). In this method, the height of the panel (product) forming surface of the punch is made higher than the upper surface of the wrinkle holding member by a predetermined dimension before the start of plate forming or at the start of wrinkle presser, and the center portion of the plate forming surface is previously formed. To do.

Further, a method has been proposed in which an aluminum alloy plate is press-formed on an automobile hood outer panel having a large bent portion and a contour line connecting the bent portion and the panel body portion curved toward the front of the panel body. (For example, see Patent Document 2). That is, in this method, the portion corresponding to the wrinkle pressing surface during press molding out of the portion corresponding to the bent portion of the plate end is shaped to fit the wrinkle pressing member surface shape during press molding. In this method, the end portion of the aluminum alloy plate is bent in advance to form a bent portion, and then press-molded while pressing the portion including the portion corresponding to the wrinkle pressing surface of the bent portion. It has also been proposed that the end portion of the aluminum alloy plate is bent in advance by a divided punch that moves independently of the punch portion for forming the panel body.
Japanese Patent Laid-Open No. 2001-58218 (full text) JP 2004-188445 A (full text)

  In the general wrinkle generation prevention method in which a draw bead formed around the material plate is formed and tension is applied as shown in FIG. 11, the forming depth is deep like the oil pan targeted by the present invention. In a molded product having a step portion in which the cross-sectional height between the upper planar molding surfaces changes suddenly, a problem that the plate material breaks during molding tends to occur. For this reason, the wrinkle suppression effect of a panel cannot fully be exhibited.

  That is, by forming a draw bead around the blank, it is possible to apply tension to the blank and reduce wrinkles 9a generated on the molding surface 3 and wrinkles 9b generated on the side walls 5. However, if enough tension is applied to eliminate these wrinkles, for molded products with a deep molding depth and varying cross-sectional height, such as the oil pan targeted by the present invention. The corners, A, B, C, D, F, G, etc. of the molded product of FIG. 8 cause a reduction in the plate thickness and breakage of the plate, and the effect of suppressing wrinkles is not sufficiently exhibited. In particular, it is difficult to prevent wrinkling and breakage in the aluminum alloy plate 33 (part corresponding to the molding surface 3) and the side wall step portion from the B point to the C point that lead to wrinkling.

  Hereinafter, the aluminum alloy plate 33 (part corresponding to the molding surface 3) from the B point to the C point is also referred to as a non-contact portion (a portion that does not contact the first punch 11 to the vicinity of the bottom dead center of the panel).

  As described above, in automobile parts such as oil pans and member parts targeted by the present invention, if a draw bead necessary for preventing wrinkles is provided, the tendency of this reduction in plate thickness becomes so large that it cannot be ignored. As a result, cracks are likely to occur at the punch shoulders A, C, and F of the blank and the shoulders B, D, and G of the die. Therefore, the general wrinkle generation preventing method for forming a draw bead formed around the material plate cannot achieve both the wrinkle generation prevention and the crack generation prevention.

  Further, the method of Patent Document 1 is applied to the non-aluminum alloy plate from the B point to the C point, which also leads to wrinkle generation, for automobile parts such as oil pans and member parts as the object of the present invention. Free deformation of the contact portion (the portion that does not contact the first punch 11 until the vicinity of the bottom dead center of the panel) 33 (the portion corresponding to the molding surface 3) cannot be restrained. For this reason, the effect of preventing wrinkle generation is weak.

  Further, the method of Patent Document 2 is unique in that the panel ridge line portion is formed by bending the plate in the front-rear direction (vehicle body longitudinal direction) with a divided punch. However, it is difficult to set the bending conditions in the longitudinal direction of the plate and the design conditions of the divided punch, and there is a problem that is not practical in this respect.

  On the other hand, while these molding problems still exist, needs for application of aluminum alloy plates such as Al-Mg-Si (6000 series), which have excellent bake hardness and recyclability, and high proof strength, to automobile body outer panels Are increasing due to the need for vehicle weight reduction and energy absorption to enhance vehicle safety to protect the global environment.

  The present invention pays attention to such a situation, and press molding method and press molding of an aluminum alloy plate that enables molding of a large-sized panel that is difficult to form, such as automobile parts such as oil pans and automobile member parts. The device is to be provided.

  In order to achieve the above object, the gist of the press forming method of the aluminum alloy plate of the present invention is to press an aluminum alloy plate on a molded product panel having a step portion in which the cross-sectional height of the upper flat forming surfaces changes suddenly. A method of molding, wherein a part of a punch portion corresponding to a molding surface having a lower sectional height of the first molding surface of the first punch for molding a panel is divided into second punches. Then, the second punch is elastically supported so as to be separately displaceable with respect to the first punch, and a wrinkle holding surface provided on the outer periphery of the die and a blank holder provided in relation thereto, When the aluminum alloy plate is press-molded by relatively moving the first punch and the die after sandwiching the outer peripheral portion of the aluminum alloy plate, Compared to the relative position of the second punch relative to the first punch at the bottom dead center of the press, the relative position of the punch is displaced to the die side in advance, and the second punch is placed on the aluminum alloy plate. While making contact with the molding surface portion on the side having a lower cross-sectional height, as the molding by the first punch proceeds, the compression force of the die due to the relative approach between the first punch and the die is applied, The punch is elastically lowered. The molded product panel targeted by the present invention is preferably a member part of an automobile. The member part of the automobile is preferably an oil pan.

  In order to achieve the above object, the gist of the aluminum alloy sheet press forming apparatus of the present invention is a press forming apparatus used in the above-described gist or the aluminum alloy sheet press forming method according to a preferred embodiment described later. The plate is press-molded by relatively moving the punch and the die after sandwiching the outer periphery of the plate with the wrinkle holding surface provided on the outer periphery of the die and the blank holder provided relative to it. A part of the punch portion corresponding to the molding surface having the lower cross-sectional height of the planar molding surface of the first punch is divided into second punches, and the second punches are divided into the second punches. It is elastically supported so that it can be displaced separately with respect to one punch.

  In the present invention, as described in the above gist, at least one second punch that can be displaced separately from the first punch for forming the central portion of the panel is used. The alloy plate is brought into contact with a molding surface portion having a low cross-sectional height, that is, a non-contact portion (a portion that does not contact the first punch 11 up to the vicinity of the bottom dead center of the panel).

  As a result, tension is generated at the non-contact portion, and free deformation of the plate portion 33 (corresponding to the molding surface 3) from the B point to the C point, which leads to wrinkle generation, is restrained and tension is applied. It is characterized in that the generation of wrinkles 9a at the contact portion 33 is prevented. In addition, due to the action of the second punch, a vertical tension is newly applied to the side wall, thereby preventing wrinkles 9b on the side wall.

  That is, in the present invention, first, in a press molding apparatus, a part of a punch portion corresponding to a molding surface having a lower cross-sectional height of the planar molding surface of the first punch for molding the panel. Is divided into second punches, which are configured to be elastically supported so that they can be displaced separately with respect to the first punch.

  Assuming the above press molding apparatus configuration, in the present invention, when the first punch forms an aluminum alloy plate in cooperation with a die, the second punch is compared with the first punch at the start of press molding. The relative position is displaced in advance to the die side as compared with the relative position at the press bottom dead center. In other words, at the start of press molding, the relative position of the second punch with respect to the first punch is larger than the relative position of the second punch with respect to the first punch at the press bottom dead center. These punches are interlocked so as to be displaced to each other.

  Thus, at the start of press forming, the aluminum alloy plate in FIG. 8 is elastically brought into contact with the forming surface portion on the side having a low cross-sectional height, that is, the plate non-contact portion 33, while forming by the first punch is performed. As it proceeds, the second punch is lowered elastically.

  Therefore, when the first punch forms the aluminum alloy plate in cooperation with the die, the second punch is in the aluminum alloy plate in FIG. 8 at the start of press forming (at an early stage of forming). This part is formed by contacting or further proceeding with the molding surface part (plate non-contact part) 33 on the side having a low cross-sectional height. As a result, it is possible to act (apply and control) the tension applied to the molding surface portion 33 and the side wall portion 38 of the aluminum alloy plate having the lower cross-sectional height, and to prevent wrinkles.

  As a result, even when an oil pan or the like targeted by the present invention is press-formed from an aluminum alloy plate, it is possible to prevent wrinkles by applying tension to the free deformation portion or the side wall portion 38. That is, as shown in FIGS. 4 and 5 and the like, the automobile has the flat molding surfaces 2 and 3 at the upper part of the panel and the stepped portion 4 such that the sectional height of the molding surfaces 2 and 3 changes suddenly. Even when parts and automobile member parts are press-formed from an aluminum alloy plate, wrinkles can be prevented.

  For this reason, it is possible to exert a suppressing effect on wrinkles generated from a relatively early stage of molding, and the wrinkles 9a on the surface of the molding surface 3 and the surfaces of the side walls 5 shown in FIGS. The generation of wrinkles 9b can be prevented.

  And in this invention, the fracture | rupture of the product (molded panel) by a 2nd punch can be prevented other than the effect of the wrinkle suppression demonstrated above (restraint of a raw material board and the function of tension | tensile_strength provision by a 2nd punch). It also has an effect. That is, since the second punch elastically contacts the plate non-contact portion 33 of the material plate from an early stage of the molding process by the first punch, a part of the molding force applied from the punch to the material plate is reduced. I can tell you from the second punch.

  In the conventional molding method, the molding force applied from the punch to the blank plate in the first half of molding is transmitted only from the molding surface 12 of the first punch. For this reason, high stress concentration occurs in the parts such as A and F in FIG. 8, and in some cases, breakage occurs in these parts. On the other hand, in the present invention, as shown in FIG. 1, since the second punch and the material plate are also in contact with the molding surface 16 on the upper surface of the punch, the range in which the molding force is transmitted from the mold to the material plate is widened. , Stress concentration can be reduced even in these parts such as A and F.

  In other words, in the present invention, the area of the punch that comes into contact with the material plate at the initial stage of molding can be increased, load transmission from the punch to the material plate (forming force transmission) can be made in a wider range, and cracking during molding can be prevented.

  As a result, it is possible to prevent wrinkling during the molding process and to prevent breakage at the punch shoulder or the like at the initial stage of molding. Further, since the tension level can be controlled to a certain value or less, it is possible to prevent the material from being extremely reduced in thickness and broken near the bottom dead center.

  As described above, according to the present invention, it is possible to achieve both the prevention of wrinkles and the prevention of cracks in the difficult molding, and an aluminum alloy panel for oil pans and automobile member parts, which is a large panel that is difficult to form. Even so, molding becomes possible.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

(Basic configuration of press machine)
First, the press device of the present invention will be described with reference to FIGS. 1 and 2 show a mode in which a die 22 that is an upper die, a first main body punch 11 that is a lower die, second punches 15 and 18, and a blank holder (wrinkle pressing member) 20 are combined. Yes.

  In FIGS. 1 and 2, the basic operation of these pressing devices, excluding the second punches 15 and 18, is the same as the conventional one. That is, the peripheral portion 31 (flange or surplus portion 8) of the aluminum alloy plate 30 is sandwiched between the die 22 and the blank holder (wrinkle pressing member) 20 and then fixed on the bolster (base) 21. The die 22 is relatively moved (lowered) toward the punch 11, and the aluminum alloy plate 30 is formed on an aluminum alloy panel of an automobile part or member part such as an oil pan.

  In the press apparatus, the lower punch 11 is fixed to the bolster 21 and does not move, and the upper die 22 is moved downward. In this respect, the lower punch 11 side may be raised, and the point is that the punch 11 and the die 22 may move relatively.

  Here, the first punch 11 serves as a main body punch, corresponding portions of the aluminum alloy plate 30, the corresponding portion 32 of the flat forming surface 2 on the upper part of the oil pan panel, the corresponding portion 33 of the forming surface 3, and these forming portions. The corresponding portion 34 of the stepped portion (vertical wall portion) 4 where the cross-sectional heights of the surfaces 2 and 3 change suddenly, the corresponding portion 36 of the rear wall 6, the corresponding portion 37 of the front wall 7, and the corresponding portion 38 of the side wall 5 are respectively formed. To do.

  For this reason, the first punch 11 has a forming surface that contacts each corresponding portion of the aluminum alloy plate 30. Specifically, the planar molding surface 12 (contacts the plate 32 portion), the planar molding surface 13 (contacts the plate 33 portion), and the stepped (vertical wall-shaped) molding surface 14 (contacts the plate 34 portion). ), A vertical wall-shaped molding surface 17a (contacts the plate 36 portion), a vertical wall-shaped molding surface 17b (contacts the plate 37 portion), a vertical wall-shaped side wall molding surface 17c (contacts the plate 38 portion), and the like. .

(Split punch configuration)
In FIG. 1, the second punch 15 divided from the first punch 11 has a cross-sectional height of the planar molding surfaces 2 and 3 of the molded panel of the first main body punch 11 for molding the panel. A part of the punch portion 13 corresponding to the molding surface 3 on the lower side is divided and formed. The second punch 15 is configured to be elastically supported by an elastic body (elastic support mechanism) such as a spring 40 so that it can be displaced separately (independently) with respect to the first punch 11. .

  FIG. 2 has the same configuration as that of the press apparatus of FIG. 1 except that two second punches 15 and 18 are arranged in order. These second punches 15 and 18 are each elastically supported by an elastic body (elastic support mechanism) such as a spring 40.

  4 and 5, the automobile parts and members having the flat molding surfaces 2 and 3 at the upper part of the panel and the stepped portion 4 such that the sectional height of the molding surfaces 2 and 3 changes suddenly. In the part, the length of the aluminum alloy plate that is in the process of being formed does not contact the die 22 or the punch 11 is relatively long.

  That is, in the forming method using a normal (conventional) single punch shown in FIG. 8, a plate non-contact portion 33 corresponding to the panel forming surface 3 on the side having a low cross section of the aluminum alloy plate being formed. Then, the length of the portion that does not contact the die 22 or the punch 11 is relatively long. In FIG. 8, the length of the portion of the plate non-contact portion 33 that does not contact the die 22 or the punch 11 is determined from the point B contacting the shoulder R portion of the molding surfaces 25 and 26 on the die 22 side to the punch 11 side. Up to C point that contacts the shoulder R portion of the molding surface 13.

  Conventionally, when the plate non-contact portion 33 (part corresponding to the molding surface 3) from the B point to the C point is freely deformed without contacting the punch 11 or the die 22 to the vicinity of the bottom dead center, this plate is used. As described above, the non-contact portion 33 is likely to have a surplus due to being pulled non-uniformly. As a result, as shown in FIG. 4 and FIG. 5, wrinkles 9a are generated on the surface (upper surface) of the molding surface 3 on which the plate non-contact portion 33 is molded and the cross-sectional height is low. Further, since the heights of the planar molding surfaces 2 and 3 are also greatly different on the surface (side surface) of the side wall 5, the magnitude of the material inflow also changes suddenly, and wrinkles 9b for eliminating this inflow difference are generated. .

(Function of split punch)
On the other hand, the second punch 15 and / or 18 in FIGS. 1 and 2 is a relative position with respect to the first punch, compared with the relative position at the bottom dead center of the press. It is supported elastically so as to be displaced in advance to the 22 side.

  1 and 2, the second punches 15 and / or 18 shown in FIGS. 1 and 2 are not in contact with the plate from the B point to the C point in the first half of press molding, particularly at the start of press molding. It has elastic contact with 33 (part corresponding to molding surface 3). Specifically, the plate non-contact portion 33 includes a shoulder R portion A on the punch 11 main body side, a B point that abuts on a shoulder R portion of the molding surfaces 25 and 26 on the die 22 side, and a shoulder R of the second punch 15. E point (E1, E2 point) of the part, C point contacting the shoulder R part of the molding surface 13 on the first punch 11 side, and D point D of the dial part have contact with the mold.

  As a result, the length in which the plate non-contact portion 33 (the portion corresponding to the molding surface 3) from the B point to the C point does not contact the mold until near the bottom dead center is significantly shortened. In addition, appropriate tension is applied in the direction indicated by the slanting arrow inclined upward to the plate in the first half of press molding including the plate non-contact portion 33 from the B point to the C point. The

  For this reason, free deformation of the plate non-contact part 33 (part corresponding to the molding surface 3) is suppressed, and during the molding, the plate non-contact part 33 is pulled unevenly and a surplus due to material inflow is left. Occurrence is suppressed. This effect is exhibited both on the surface side (upper surface side) of the molding surface 3 on the side having a low cross-sectional height and on the surface side (side surface side) of the side wall 5. As a result, as shown in FIG. 4 and FIG. 5, 9a is generated on the surface (upper surface) of the molding surface 3 on the side having a low cross section height, and 9b is also generated on the surface (side surface) of the side wall 5. Wrinkles are suppressed.

(Division punch mode)
In order to exhibit the above functions (effects), the second punch 15 corresponds to the molding surface 3 on the side where the cross section height of the first main body punch 11 for molding the panel is low as shown in FIGS. It is necessary to divide from the first punch 11 so as to divide a part of the surface of the punch portion 13 to be cut (in the surface corresponding to the plate non-contact portion 33).

  As shown in FIG. 3 showing another aspect of the divided punch, the second punch 15 is not necessarily provided in the vicinity of the step forming surface 14 as long as it is within the surface of the punch portion 13. A part of the punch part 13 that is separated to some extent may be divided.

  On the other hand, for example, as shown in FIG. 9, a part of the punch portion 12 corresponding to the molding surface 2 on the side where the cross section height of the first main body punch 11 is high is divided and supported by the spring 51. In the case where the punch 50 is used, the punch 50 is particularly dislocated from the plate non-contact portion 33. For this reason, the second punch 50 does not come into contact with the plate non-contact portion 33, and free deformation of this portion cannot be prevented. As a result, the function (effect) of the above-described divided punch is not exhibited as in the examples described later, and the surface side (upper surface side) of the molding surface 3 on the side having a low cross-sectional height is also on the surface side of the side wall 5 ( Both side wrinkles 9a and 9b are likely to occur.

  Further, when the forming surface on the die 22 side is divided into the divided die 52 instead of the divided punch 15 as shown in FIG. 10, the effect of the divided punch is as shown in FIG. Although it is exhibited on the surface side (upper surface side) of the molding surface 3 on the lower side, it is not exhibited on the surface side (side surface side) of the side wall 5, and the effect cannot be exhibited on both. As a result, the generation of wrinkles 9a on the surface side (upper surface side) of the molding surface 3 is suppressed, but the generation of wrinkles 9b on the surface (side surface) of the side wall 5 of the molding surface 3 on the side having a low cross-sectional height is suppressed. Not.

  In FIG. 10, the molding surface 24 on the die 22 side (the molding surface corresponding to the panel molding surface 3 on the side having a low cross-sectional height) is divided into divided dies 52 and elastically supported by springs 53. ing.

  The number and interval of the second punches 15 to be provided, the size of the molding surface, etc. are described above according to the size and shape of the panel molding surface 3 on the side having a low cross-sectional height and the punch molding surface 13 corresponding thereto. Design appropriately so that the function (effect) can be demonstrated. For example, when the punch forming surface 13 in FIG. 2 is larger or longer than that in FIG. 1, a plate being formed with the same tension as FIG. 1 (particularly the plate non-contact portion 33 from the B point to the C point). 2 is increased, the number of second punches 15 to be provided is increased as shown in FIG. 2 is the same size or length as in FIG. 1, but in order to control with finer tension when the panel shape accuracy requirement is more severe than in FIG. As shown in FIG. 2, the number of second punches 15 to be provided is increased.

(Support mechanism for split punch)
Each of the second punches 15 and 18 is elastically supported by an elastic body (elastic support mechanism) such as a spring 40. By the elastic support by the spring 40, the second punches 15 and 18 can be separately displaced with respect to the first punch 11. In other words, the relative positions of the second punches 15 and 18 with respect to the first punch 11 at the start of molding, particularly at the start of molding, are determined as the second punches 15 and 18 with respect to the first punch 11 at the press bottom dead center. Compared to the relative position, the die can be displaced in advance. As a result, the second punches 15 and 18 can be elastically brought into contact with the molding surface portion 33 on the side having a low cross-sectional height in the aluminum alloy plate.

  On the other hand, as the molding by the first punch 11 progresses due to the elastic support by the spring 40, the second punch 15, 18 is moved to the die 22 according to the relative approach between the first punch 11 and the die 22. By applying a compressive force from above, the second punches 15 and 18 can be elastically lowered (sunk downward). For this reason, at the press bottom dead center, the relative position of the second punches 15 and 18 with respect to the die moves toward the first punch 11 as compared to during press molding. Thereby, a product shape having a difference in height of a predetermined molding surface is obtained.

  Due to the elastic support of the second punches 15 and 18 by the spring 40, as the molding proceeds, the movement of the second punch toward the die is stopped, and the molding is performed while maintaining the state in which the plate is sandwiched between the die. can do.

  Further, such an elastic support mode can be achieved by combining the second punch and an elastic support mechanism (means) such as a spring or a die cushion, and can be achieved with a relatively simple mold configuration. It is preferable in terms of equipment. On the other hand, when a mechanism for independently controlling the displacement of the second punch is provided for the first punch, the press apparatus becomes complicated in terms of equipment.

(Specific embodiment of press device)
1 and 2, the punch 11 is rigidly mounted on the bolster. On the other hand, the second punches 15 and 18 are coupled to the bolster 21 via the elastic body such as the spring 40 or the gas spring described above, and a compressive force is applied to the second punches 15 and 18 from above. For example, the structure sinks downward. As another embodiment, a plurality of second punches 15 are provided as described above, and each of the second punches 15 can be moved forward and backward (movable up and down) individually with respect to the upper die via a drive device such as a separate hydraulic pressure. It may be configured.

  The upper die 22 is attached to a slide (not shown) connected to the lifting device. The dies 22 have molding surfaces such as 24, 26 (corresponding to the molding surfaces 2 and 3), 25 (corresponding to the step 4) corresponding to the molding surfaces 2 and 3 and the step 4 at the center of the molded product, respectively. Yes.

  Further, an outer frame-shaped wrinkle pressing surface (periphery of the molded product) is provided on the outermost peripheral portion of the die 22 at positions facing the wrinkle pressing surfaces (upper surface) 20a, 20a of the lower die blank holder (wrinkle pressing member) 20, respectively. 27 and 27 are formed. The blank holder 20 is held by a cushion pin 23, and an upward force generated by a hydraulic mechanism at the lower part of the press device is transmitted to the blank holder 20 through the cushion pin 23, and the blank is held as a wrinkle holding force. Used to do.

(Specific Mode of Molding)
A specific embodiment of press forming of the aluminum alloy plate of the present invention will be described with reference to FIGS.

  In the state before the start of molding in which the aluminum alloy plate 30 is set in the press device of FIGS. 1 and 2, the outermost peripheral portion 31 of the plate 30 is provided with the wrinkle holding surfaces 27 and 27 positioned at the peripheral portion of the die 22 and the blank holder 20. , 20 with the appropriate wrinkle pressing force. This wrinkle holding force may be in a range used in press forming of a normal aluminum alloy plate. Here, the blank holder 20 is held at the upper limit position by the cushion pin 23 before the aluminum alloy plate 30 is set.

(First half of molding: second punch action)
As shown in FIGS. 1 and 2, for example, when the die 22 is lowered to a position 65 mm above the bottom dead center position of the molding, the blank holders 20 and 20 are part of the die 22 as the die 22 is lowered. With the cooperation of the wrinkle pressing surfaces 20a, 20a and the wrinkle pressing surfaces 27, 27 located around the die 22, the aluminum alloy plate 30 is sandwiched and moved down.

  In this state, following the start of molding of the first punch 11, the second punch 15 starts contacting or molding with the plate non-contact portion 33. Therefore, the second punches 15 and 18 are in a state of being displaced in advance toward the die 22 side in order to start contact or molding to the plate non-contact portion 33 at the earliest possible timing. That is, the relative position of the second punch 15 with respect to the first punch 11 is closer to the die 22 than the relative position of the second punch 15 with respect to the first punch 11 at the press bottom dead center. It is displaced in advance.

  Here, if the non-contact portion can be eliminated and the tension applied to the material plate can be controlled and the effect of preventing the wrinkle deformation of the material plate can be exhibited, the second punches 15 and 18 are attached to the plate non-contact portion 33. Whether to simply make contact or to positively form this portion is appropriately selected. However, under normal press molding conditions, it is preferable not only to contact the non-contact part (the part that does not contact the first punch to the vicinity of the bottom dead center of the panel) but to further proceed to form this part. . This is because forming this portion easily eliminates the non-contact portion, controls the tension applied to the material plate, and easily exerts the effect of preventing wrinkle deformation of the end portion of the material plate.

(Forming the plate with the first punch)
The die 22 continues to descend toward the first punch 11 and the forming of the plate 30 by the first punch 11 proceeds. That is, the product forming surfaces 12, 13, 14 and the like of the first punch 11 cooperate with the product forming surfaces 24, 25, 26 and the like of the die to form the plate into the panel portions 2, 3, and 4.

  At this time, as described above, the plate 30 formed by the first punch 11 by the second punches 15 and 18 that have already started forming the plate non-contact portion 33 and the contact or plate non-contact portion 33, The punch 11 body side shoulder R part A, the die 22 side molding surface 25, contact the shoulder R part of the 26, the second punch 15, 18 side molding surface 16, 19 contact the shoulder R part At the points E1 and E2, the point C contacting the shoulder R portion of the molding surface 13 on the punch 11 side, and the point D of the dial portion, contact with the mold is restricted.

  As a result, when the first punch 11 forms the aluminum alloy plate 30 in cooperation with the die 22, the first punch 11 can be formed while restraining the plate non-contact portion 33 by applying tension from the mold. It becomes possible. For this reason, as shown in FIGS. 4 and 5 such as the oil pan which is the subject of the present invention, the flat upper surfaces of the panel have the molding surfaces 2 and 3, and the sectional heights of these molding surfaces 2 and 3 are high. Even when an automobile part or member part having a stepped portion 4 whose height changes abruptly is press-formed from an aluminum alloy plate, the above-mentioned free deformation portion is eliminated and the entire region of this plate (panel being formed) is covered. Thus, tension can be applied.

  As a result, it is possible to exert a suppressing effect on wrinkles generated from a relatively early stage of molding, and the wrinkles 9a on the surface of the molding surface 3 and the surfaces of the side walls 5 shown in FIGS. The generation of wrinkles 9b can be prevented. Further, the molding load applied from the punch to the material plate is transmitted from the molding surfaces 16 and 19 on the second punch 15 and 18 side in addition to the molding surface 12 of the first punch 11, and the shoulder A of the mold, Stress concentration at the plate portion due to F or the like is relaxed, and breakage can be prevented.

(The second half of molding: Near bottom dead center of molding)
After the above-described state, a case will be described in which the die 22 moves (lowers) toward the first punch 11 to a position 32 mm above the molding bottom dead center. In this state, the wrinkle suppressing action by the second punches 15 and 18, that is, the function of contacting or forming the plate non-contact portion 33 by the second punches 15 and 18 increases with the progress of contact or forming. The molding surface 26 of the die 22 and the molding surfaces 16 and 19 of the second punches 15 and 18 are maximized at a position where the plate non-contact portion 33 is sandwiched without a gap.

  However, this function does not need to be further increased in the subsequent molding steps, and may be approximately the same thereafter. That is, after the first punch 11 is relatively moved (raised) up to 32 mm toward the die 22, it is only necessary to apply the same level of tension. As described above, whether or not the wrinkle 9 a on the upper surface of the molding surface 3 and the wrinkle 9 b on the side surface of the side wall 5 are generated is determined in the first half of the molding process using the first punch 11.

(Descent of second punch)
On the other hand, in the present invention, in the latter half of the molding process, in order to obtain the final shape of the molded product, the second punches 15 and 18 are elastically moved as the molding progresses and the die 22 approaches the bottom dead center. Lower. This elastic lowering itself is possible by applying a compressive force from above to the second punches 15 and 18 by the die 22 in accordance with the relative approach between the first punch 11 and the die 22. . That is, the spring 40 that supports the second punches 15 and 18 can be contracted by the compressive force from above the die 22, and the second punches 15 and 18 can be elastically lowered (sunk downward). .

  Due to the elastic lowering of the second punches 15 and 18, the relative position of the second punches 15 and 18 with respect to the die is closer to the first punch 11 side at the press bottom dead center than during press molding. Moving. Eventually, the second punches 15 and 18 stop at a position where they are lowered downward, and finish forming the panel while forming the same step as the product shape. Thereby, the final product shape panel can be accurately press-formed by the action of the second punch, even though the shape of the molding die during press molding is different from the final product shape.

  The panel molded product molded as described above is finished into an automotive part such as an oil pan or a member part panel by being partially molded or trimmed.

  In the present invention, as described above, it is possible to achieve both prevention of wrinkling and prevention of cracking during panel molding. As a result, according to the present invention, even a large-sized panel that is difficult to be molded, such as an automobile part such as an oil pan or a member part, can be molded.

(Aluminum alloy)
The aluminum alloy used in the present invention includes 3000 series, 5000 series, 6000 series, and 7000 series that are specified or included in AA to JIS standards according to required characteristics for panel use such as rigidity, strength, formability, and corrosion resistance. An aluminum alloy material selected from the above is appropriately selected.

  Examples of the present invention will be described below. An aluminum alloy plate of AA5182-O material was drawn into an oil pan 1a having the shape shown in FIG. And the wrinkle generation situation of a molded article was investigated.

  The aluminum alloy plate had a 0.2% proof stress of 130 MPa, a tensile strength of 250 MPa, an elongation of 30%, and a plate thickness of 1.0 mm. Moreover, the shape and dimension of each part of the molded oil pan 1a were as shown in FIGS. 6 (a) and 6 (b). The unit of the numerical value displayed in FIG. 6 is mm.

  The press apparatus used in the invention example used a press apparatus 10 (single-acting mechanical press machine) in which the punch was divided. The invention example 1 used the press apparatus shown in FIG. 1, and the invention example 2 used the press apparatus shown in FIG. In Comparative Example 1, the conventional press device using an integral punch shown in FIG. 8 was used. In Comparative Example 2, the press apparatus shown in FIG. 10 was used. In Comparative Example 3, the press apparatus shown in FIG. 9 was used. For lubrication between the material and the mold, a commercially available cleaning rust preventive oil (viscosity 3.9 cSt) was used, the molding speed was 5 spm, and the wrinkle holding force was 200 kN.

  The molding method of the invention example was a specific embodiment of the above paragraphs 0067-0079. Here, the relative position of the second punch 15 with respect to the first punch 11 is compared with the relative position of the second punch 15 with respect to the first punch 11 at the press bottom dead center. Previously displaced by 70 mm. Thus, following the forming of the material plate by the first punch 11, the second punch 15 is brought into a floating state in advance so as to start contact with or form the plate non-contact portion 33.

  The evaluation of the occurrence of wrinkles in the molded product was performed by visually evaluating the occurrence of both the wrinkles 9a on the upper surface of the molding surface 3 and the wrinkles 9b on the side surfaces of the side walls 5, and averaged five times for each molding test. A product with a high score was regarded as a non-defective product. The score of the upper wrinkle 9a was 1 point when multiple overlapping wrinkles occurred, 3 points when only 1 overlapping wrinkle occurred, and 5 points when no overlapping wrinkles occurred. The side wrinkle 9b has a score of 1 point when even one wrinkle occurs, 2 points when a wrinkle with a depth of 5 mm or more occurs, 3 points when a wrinkle with a depth of 5 mm or less and more than 3 mm is generated. In the case where wrinkles with a depth of 3 mm or less were generated, 4 points were given, and when no wrinkles were given, 5 points were given.

  As shown in FIG. 7, in Invention Examples 1 and 2, the score of the upper surface wrinkle 9a is 5, no wrinkle is generated, the side wrinkle 9b also has a score of 3, and the wrinkle has a depth of 5 mm or less. It is suppressed.

  On the other hand, in Comparative Example 3, the score of the upper wrinkle 9a is 3, and overlapping wrinkles are generated. In Comparative Example 1, both the upper wrinkle 9a and the side wrinkle 9b have a score of 1, and wrinkles are generated on both surfaces. In Comparative Example 2, the score of the upper surface wrinkle 9a is 1, and the side surface wrinkle 9b is particularly generated.

  In addition, as a result of visually evaluating the cracks of the molded products, no cracks occurred in the inventive examples and the comparative examples. From these Examples, the effect of suppressing wrinkles when molding a difficult-to-form panel by the molding method of the present invention is supported.

  According to the present invention, as described above, it is possible to achieve both prevention of wrinkling and prevention of cracking during panel molding. As a result, even large panels that are difficult to form, such as automobile parts such as oil pans and member parts, can be formed. For this reason, the use of the aluminum alloy plate as a forming material is greatly expanded for automobile parts and member parts, and the industrial value is great.

It is sectional drawing of the press apparatus which shows 1 aspect of this invention. It is sectional drawing of the press apparatus which shows the other aspect of this invention. It is sectional drawing of the punch which shows the other aspect of the punch division | segmentation of this invention. It is a perspective view which shows the one aspect | mode of an oil pan. It is a perspective view showing one mode of other automobile parts. It is a perspective view which shows the shape of the oil pan which carried out the shaping | molding test. It is a perspective view which shows the score of wrinkle generation | occurrence | production of each oil pan example which carried out the shaping | molding test. It is sectional drawing of the press apparatus which shows the one aspect | mode of the conventional shaping | molding method. It is sectional drawing of the punch which shows the comparative example which is another aspect of punch division | segmentation. It is sectional drawing of the punch which shows the comparative example which is another aspect of punch division | segmentation. It is a fragmentary sectional view of the press apparatus which shows the conventional forming method.

Explanation of symbols

1: oil pan, 2, 3: top surface of molding surface, 4: stepped portion,
5, 6, 7: side wall (vertical wall), 8: flange, 9: wrinkle, 10: press device,
11: 1st punch, 12, 13, 14, 17: Punch molding surface,
15, 18, 50, 52: second punch, 16, 19: second punch forming surface,
40, 51, 53: Spring, 20: Blank holder, 21: Bolster,
22: Die, 23: Cushion pin, 24, 25, 26: Die molding surface,
30: plate, 31: outermost peripheral portion of plate, 32-37: molding surface of plate,

Claims (4)

  A method of press-molding an aluminum alloy plate on a molded product panel having a stepped portion in which the cross-sectional height of the upper planar molding surfaces changes suddenly, and the planar molding of the first punch for molding the panel A part of the punch portion corresponding to the molding surface with the lower cross-sectional height of the surface is divided into the second punch so that the second punch can be separately displaced with respect to the first punch. The first punch and the die are relative to each other after the outer peripheral portion of the aluminum alloy plate is sandwiched between the wrinkle holding surface provided on the outer periphery of the die and the blank holder provided opposite thereto. When the aluminum alloy plate is press-molded, the relative position of the second punch with respect to the first punch is changed to the second punch with respect to the first punch at the press bottom dead center. punch Compared to the relative position, it is displaced in advance to the die side, and the second punch is brought into contact with the molding surface portion on the side of the aluminum alloy plate where the cross-sectional height is low, while the molding by the first punch proceeds. A press forming method of an aluminum alloy plate, wherein a compressive force of a die due to a relative approach between the first punch and the die is applied to lower the second punch elastically.   The method of press-forming an aluminum alloy plate according to claim 1, wherein the molded product panel is a member part of an automobile.   The aluminum alloy sheet press forming method according to claim 2, wherein the member part of the automobile is an oil pan.   A press forming apparatus for use in the press forming method for an aluminum alloy plate according to any one of claims 1 to 3, wherein the outer peripheral portion of the plate is formed by a wrinkle holding surface provided on the outer periphery of the die and a blank holder provided opposite thereto. The plate is press-molded by relatively moving the punch and the die, and the molding surface on the side having the lower cross-sectional height of the planar molding surface of the first punch is used. An aluminum alloy plate characterized in that a part of the corresponding punch portion is divided into second punches and elastically supported so that the second punches can be displaced separately with respect to the first punches. Press molding equipment.

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