JP2007283388A - Axle case manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axle case manufacturing method for enhancing the reliability of a welded part, and preventing cracks during the press-forming. <P>SOLUTION: In the method of manufacturing an axle case 1 for press-forming a half-split side plate member 6 from a blank 4 when manufacturing the axle case 1, each wall-increased portion 41 is provided on an end on a hole part 21 side of a part forming each straight tubular part 3 by press-forming the blank 4; the blank 4 is bent in a channel shape to respectively form flanges forming a banjo part 2 and the straight tubular portion 3; the banjo part 2 is pushed downwards, and the straight tubular portions 3, 3 upwardly so as to be bent in a V-shape; the V-shaped formed member 5 is pushed from above to bend the straight tubular portions 3, 3 downwards with an end on the banjo part 2 side as a supporting point to match the axes of the straight tubular parts 3, 3 with each other, and extend in the longitudinal direction; and the wall-increased portion is pushed toward the flanges of the straight tubular parts when the straight tubular part 3 is extended in the longitudinal direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an axle case that accommodates a truck drive shaft and the like.

  2. Description of the Related Art Conventionally, as an axle case that accommodates a track drive shaft, an axle case is known in which a banjo portion that accommodates a differential or the like is provided in a central portion in a longitudinal direction.

  As a typical method of manufacturing such an axle case by welding assembly of plate material press-formed products, a method of constructing an axle case by joining parts (plate material press-formed products) of two upper and lower side plate members has been proposed. (For example, refer to Patent Document 1).

  As shown in FIG. 8, conventionally, the side plate member 91 is made of a blank material 92 having a shape in which the side plate member 91 is developed, using a mold 93 as shown in FIG. It is manufactured by press molding into a channel shape constituted by a flange.

  However, in the conventional method of manufacturing the side plate member, when the blank material 92 is press-bended, the flange of the straight pipe portion 95 is stretched and flange-formed, resulting in a problem that the material thickness is reduced (in FIG. 8). (Indicated by the symbol D). Therefore, depending on the length and shape of the axle case, there is a risk of cracking during press molding.

  Therefore, a manufacturing method using a triangular plate 96 as shown in FIG. 9 has been proposed for the purpose of preventing cracking by such stretch flange molding and improving the material yield of the side plate member (see Patent Document 2).

JP-A-5-228568 JP 2004-262328 A

  However, in the manufacturing method of FIG. 9, the part to be stretched flange molding is a triangular plate 96 as a separate part, so there is no problem of thinning the flange during press molding, but welding becomes complicated and the reliability of the welded portion is ensured. There is a problem that it is difficult to do.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing an axle case that can solve the above-described problems and can improve the reliability of a welded portion and prevent cracking during press molding.

  In order to achieve the above object, the present invention provides an axle case having a banjo part in which a hole for accommodating a differential is opened and a straight pipe part extending from the banjo part to both sides in the axial direction of the axle. In the manufacturing method of the axle case in which the side plate members are formed from the blank material by press molding when the split side plate members are joined to each other, each straight pipe portion is formed by press forming the blank material in advance. A thickened portion is provided at each end of the hole portion, and the blank material is bent into a channel shape to form flanges that form the banjo portion and the straight pipe portion, and the banjo portion is disposed below. Then, both straight pipe parts are pushed upward to bend into a V shape, the V-shaped molding material is pushed from above, and both straight pipe parts are used with the end on the banjo part side as a fulcrum. When the straight pipe part is bent in each direction and the axes of both straight pipe parts are aligned and extended in the longitudinal direction, and the straight pipe part is extended in the longitudinal direction, the increased thickness part is pushed toward the flange of the straight pipe part. is there.

  Preferably, the V-shaped bending process of the blank material is performed such that the angle formed by both straight pipe portions is 120 to 150 °.

  According to the present invention, the excellent effect of improving the reliability of the welded portion and preventing cracking during press molding is exhibited.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The axle case manufacturing method of the present embodiment is intended for an axle case (axle housing) of a truck drive shaft, for example.

  First, the axle case of this embodiment will be described with reference to FIG.

  As shown in FIG. 1, the axle case 1 includes a banjo part 2 in which a differential is accommodated, and a straight pipe part 3 that extends from the banjo part 2 to both sides in the axial direction of the axle and accommodates the axle.

  The straight pipe portion 3 includes circular pipe portions 32 and 32 formed at both ends of the axle case 1 and square pipe portions 31 and 31 connecting the circular pipe portions 32 and 32 and the banjo portion 2.

  The banjo portion 2 is formed with a hole 21 for storing the differential in the axle case 1 and is formed in a ring shape that protrudes up and down as a whole. The hole portion 21 of the banjo portion 2 is closed by attaching a lid member (not shown).

  In the present embodiment, the above axle case 1 is formed by joining the half-shaped side plate members 6 and 6. The side plate member 6 has a shape obtained by dividing the axle case 1 into two along the axial direction (upper and lower divided shapes in FIG. 1).

  The side plate member 6 has a channel shape (gutter shape) constituted by a flange, and the upper half (or the lower half) of the straight pipe portions 3 and 3 and the banjo portion 2 are formed by the flange.

  Next, the manufacturing apparatus of the axle case 1 of this embodiment is demonstrated based on FIGS.

  A manufacturing apparatus for the axle case 1 includes a bend mold 7 (see FIG. 2) for press-molding the blank material 4 shown in FIG. 4 into a V-shaped molding material 5 (intermediate material), and a V-shaped molding material 5. And a wrist-like mold 8 (see FIG. 3) for press-forming the side plate member 6 on the side plate member 6.

  As shown in FIG. 2, the bend mold 7 is placed on the bend pad 72 and a pair of bend dies 73 (only one is shown in FIG. 2) held in the holder 71, and on the bend pad 72 and the bend die 73. And a V-shaped punch 74 that presses the blank 4.

  The lower surface of the V-shaped punch 74 is provided at a central portion in the longitudinal direction and has a curved curved portion molding surface 741 that protrudes downward, and from the curved portion molding surface 741 to both sides in the longitudinal direction and upward with a predetermined molding angle. Inclined portion forming surfaces 742 that are inclined and extend.

  The bend dies 73 are disposed on both sides of the bend pad 72 in the width direction, and the upper surface 721 of the bend pad 72 and the side surface 731 of the bend die 73 form a U-shaped forming surface as a whole.

  In the present embodiment, the forming surface (upper surface) 721 of the bend pad 72 and the inclined portion forming surface (lower surface) 742 of the V-shaped punch 74 have the same inclination angle (forming angle, indicated by symbol C in the figure). In the illustrated example, the inclination angle is set to 15 to 30 ° with respect to the horizontal plane.

  As shown in FIG. 3, the wrist-like mold 8 includes a wrist-like pad 82 and a pair of wrist-like dies 83 (only one is shown in FIG. 3) held in a holder 81, the wrist-like pad 82 and the wrist A wrist-like punch 84 that presses the V-shaped molding material 5 placed on the like die 83.

  The wrist-like punch 84 is provided so as to protrude outward in the width direction above the wrist-like molding portion 85 and the wrist-like molding portion 85 for pressing the inner surface 51 (see FIG. 4) of the V-shaped molding material 5. And a wrist-like stepped portion 86 for pressing the upper end surface 52 (see FIG. 4) of the V-shaped molding material 5 from above.

  The lower surface of the wrist-like stepped portion 86 is provided at the central portion in the longitudinal direction and has a substantially semicircular (side view) banjo portion molding surface 861 that protrudes downward, and horizontally from the banjo portion molding surface 861 to both sides in the longitudinal direction. Each is formed by a straight pipe part forming surface 862 extending.

  The wrist-like dies 83 are disposed on both sides of the wrist-like pad 82 in the width direction, and the upper surface 821 of the wrist-like pad 82 and the side surfaces 831 of the pair of wrist-like dies 83 form a molding surface.

  Next, the manufacturing method of the axle case 1 of this embodiment is demonstrated.

  As shown in FIG. 1, the manufacturing method of the axle case 1 includes a banjo part 2 in which a hole 21 for accommodating a differential is opened, and a straight pipe part 3 extending from the banjo part 2 to both sides in the axial direction of the axle. Is manufactured by joining the half-shaped side plate members 6 and 6 to each other, the side plate member 6 is formed from the blank material 4 by press molding.

  As shown in the upper part of FIG. 4, in the present embodiment, each of the thickened portions 41 is provided in advance at the end portion on the hole 21 side of the portion that becomes each straight pipe portion 3 by press molding of the blank material 4 (blank process). ).

  In the blanking process, the plate material is punched out with a mold or the like to form the blank material 4 having a shape in which the side plate member 6 is developed. In this embodiment, the plate material is sized to match the expanded portion 41 with the developed shape. By punching, the blank portion 4 is provided with a thickened portion 41. For example, a blank is formed by punching a plate material with a dimension in which the thickened portion 41 (restrictive material) is added as shown in the upper part of FIG. 4 with respect to the dimension of the blank member 92 of the conventional manufacturing method shown in the upper part of FIG. A material 4 is formed.

  Next, as shown in the middle part of FIG. 4, the blank material 4 is bent into a channel shape (saddle shape) to form flanges forming the banjo part 2 and the straight pipe part 3, and the banjo part 2 is moved downward. Then, both straight pipe portions 3 and 3 are pushed upward (on the open side of the channel), respectively, and bent as a whole into a V shape with the central portion in the longitudinal direction curved downward (V-shaped bending step).

  In the V-shaped bending step, the blank material 4 is press-molded into the V-shaped molding material 5 using the bend die 7 shown in FIG.

  Specifically, the blank material 4 is placed on the bend pad 72 and the bend die 73, and then the V-shaped punch 74 is lowered to press the blank material 4 downward.

  At this time, the blank 4 is press-molded in a U-shaped cross section, and flanges are formed on both sides in the width direction. Further, a curved portion projecting below the banjo portion 2 (outside the channel) is formed by the curved portion molding surface 741 of the V-shaped punch 74. The straight pipe portions 3 and 3 are bent by the inclined portion forming surface 742 and the forming surface 721 of the bend pad 72 so as to incline upward from the end portion on the banjo portion 2 side.

  Thereby, the molding material 5 having a U-shaped cross-section and a V-shape in side view is formed.

  Here, in the V-shaped bending process of the present embodiment, the V-shaped bending forming angle (the angle formed by the straight pipe parts 3 and 3 or the angle formed by the straight pipe part 3 and the horizontal plane) is a two-process described later. It is set so that the indentation of the material and the timing of the stretch flange molding are the same in the eye restructuring process. In the illustrated example, the blank material 4 is bent into a V shape so that the angle between the straight pipe portions 3 and 3 (the crossing angle between the axes of the straight pipe portions 3 and 3) is 120 to 150 °. That is, in the first V-shaped bending step, an angle formed by each straight pipe portion 3 and a horizontal plane (forming angle, indicated by a symbol C in FIG. 5) is adjusted in a range of 15 to 30 °.

  Next, as shown in the lower part of FIG. 4 and FIG. 5, the V-shaped molding material 5 is pushed from above, and both straight pipe parts 3 and 3 are bent downward with the end on the banjo part 2 side as a fulcrum. The straight pipe portions 3 and 3 are substantially aligned with each other in axis, and the straight pipe portions 3 and 3 are extended outward in the longitudinal direction. Further, when the straight pipe portion 3 is extended in the longitudinal direction, the thickened portion 41 is pushed toward the flange of the straight pipe portion 3 (restriction process).

  In the wrist-like process, the V-shaped molding material 5 is press-molded on the side plate member 6 by using the wrist-like mold 8 shown in FIG.

  Specifically, the V-shaped molding material 5 is placed on the wrist-like pad 82 and the wrist-like die 83, and then the wrist-like punch 84 is lowered, and the wrist-like molding unit 85 causes the V-shaped molding material 5 to be lowered. Is pressed from the inner surface 51 side, and the upper end surface 52 of the V-shaped molding material 5 is pressed downward by the wrist-like stepped portion 86.

  At this time, as shown in FIG. 5, the straight pipe part 3 has its outer surface on the banjo part 2 side constrained by the molding surface 821 of the wrist-like pad 82, and in this state, the straight pipe part molding surface 862 of the wrist-like punch 84. Thus, the upper end surface 52 on the distal end side (longitudinal direction outer side) of the straight pipe portion 3 is pushed downward.

  Thereby, the straight pipe part 3 bends downward centering on the end part on the banjo part 2 side, and the flange in the vicinity of the banjo part 2 in the straight pipe part 3 is stretched in the longitudinal direction to be stretched flange-molded.

  At the same time as the flange is extended, the thickened portion 41 is pushed from the hole portion 21 side toward the flange side (longitudinal direction outer side) of the straight pipe portion 3 by the banjo portion molding surface 861 of the wrist-like punch 84.

  Thereby, since the material of the thickening part 41 is sent into the flange of the straight pipe part 3 by which stretch flange molding is carried out, the thinning of the stretch flange molding location (indicated by symbol D in FIG. 5) is suppressed. As a result, the thickness reduction of the stretch flange is reduced and cracking is prevented.

  When the wrist punch 84 reaches the bottom dead center, the side plate member 6 as shown in the lower part of FIG. 4 is formed.

  Thereafter, a pair of press-molded side plate members 6 and 6 are joined by welding or the like, and a lid member (not shown) is used to manufacture the axle case 1 (see FIG. 1).

  Thus, in this embodiment, when manufacturing the axle case 1 of the track drive shaft using the side plate member 6 (plate material press-molded product) divided into the upper and lower parts, when the side plate member 6 is pressed, stretch flange molding is performed. It is possible to prevent the straight pipe portion 3 from being cracked.

  As a result, the side plate member 6 of the axle case 1 of the track drive shaft, which has conventionally been difficult to press-mold, can be press-molded, increasing the degree of freedom in designing the press product.

  Further, since the triangular plate 96 as shown in FIG. 9 is not used, welding is simplified and the reliability of the welded portion can be improved.

  By the way, conventionally, for example, in the manufacturing method shown in FIG. 8, after the blank material 92 is press-molded with the mold of FIG. 7, the press-molded product is further subjected to finish molding (form) and a circular pipe portion (plate end surface). ) Is performed in the second step.

  Since the manufacturing method of this embodiment can simultaneously perform foaming and restructuring (finish molding) in the second step, the same molding can be performed with the same number of steps as in the conventional method.

  That is, in this embodiment, the press working step is two steps. However, since the side plate member 6 can be finished and the end face (circular tube portion 32) can be subjected to restric processing in the second step, the side plate member is used as in the conventional method. The side plate member 6 can be manufactured with the same number of steps as in the case where the molding (form) and the plate end face re-striking are performed in two steps, and the die cost and the processing cost can be similarly reduced.

  Here, in order to confirm the thinning suppression effect by the manufacturing method of the axle case of this embodiment, the comparison with the conventional manufacturing method of FIG. 8 mentioned above was performed by simulation. In the simulation, it was simulated that the side plate member 6 having a diameter of 145 mm was press-molded as shown in FIG.

  In the case of the manufacturing method of this embodiment, the plate thickness maximum reduction rate of the flange of the straight pipe portion was 12.8% (indicated by reference sign D in FIG. 6). In the case of the conventional manufacturing method, the maximum reduction rate of the plate thickness was 16.6%. From this result, it can be seen that the axle case manufacturing method of the present embodiment can suppress a reduction in the plate thickness of the flange of the straight pipe portion and can prevent cracking as compared with the conventional manufacturing method.

  Thus, in this embodiment, the plate | board thickness reduction | decrease of the flange of a straight pipe part can be suppressed, and a crack can be prevented.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, the present invention can be applied to the molding of a part in which the flange height changes in a channel-shaped part that is stretch-flange-molded, so that strain concentrates on the stretch-flange portion and a crack occurs.

FIG. 1 is a perspective view of an axle case according to an embodiment of the present invention. FIG. 2 is a perspective view of a mold used in the first step of press working in the axle case manufacturing method of the present embodiment. FIG. 3 is a perspective view of a mold used in the second step of press working in the axle case manufacturing method of the present embodiment. FIG. 4 is a view for explaining a manufacturing method of the axle case of the present embodiment. FIG. 5 is an enlarged side view of a portion V in FIG. FIG. 6 is a perspective view of the axle case used in the simulation of the present embodiment. FIG. 7 is a perspective view of a mold used in a conventional method for manufacturing an axle case. FIG. 8 is a diagram for explaining a conventional method of manufacturing an axle case. FIG. 9 is a diagram for explaining a conventional method of manufacturing an axle case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axle case 2 Banjo part 3 Straight pipe part 4 Blank material 5 V-shaped molding material 6 Side plate member 21 Hole part 41 Thickening part

Claims (2)

An axle case having a banjo part with a hole for accommodating a differential and a straight pipe part extending from the banjo part to both sides in the axial direction of the axle is manufactured by joining halved side plate members together. In doing so, in the method of manufacturing an axle case, the side plate member is formed from a blank material by press molding.
In each end of the hole portion side of the portion to be a straight pipe portion by press molding of the blank material in advance, a thickened portion is provided,
The blank is bent into a channel shape to form flanges forming the banjo part and the straight pipe part, and the banjo part is pushed downward and both straight pipe parts are pushed upward to bend in a V shape. Processed
The V-shaped molding material is pushed from above, and both straight pipe parts are bent downward with the end on the banjo part side as a fulcrum so that the axes of both straight pipe parts coincide and extend in the longitudinal direction. A method for manufacturing an axle case, wherein when the straight pipe portion is extended in a direction, the thickened portion is pushed toward a flange of the straight pipe portion. The method for manufacturing an axle case according to claim 1, wherein the blank material is bent so that an angle formed by both straight pipe portions is 120 to 150 °.

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