JP2008201416A - Manufacturing method of casting suspension member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a manufacturing method of a casting suspension member capable of achieving compatibility between assuring of strength relative to a load input from a suspension arm to a suspension member and prevention of an increase in assembly stress that occurs at assembly of the suspension arm to the suspension member. <P>SOLUTION: The board thickness of a rear side mounting base 26 supporting the end of the suspension arm is set to be thicker than that of a front side mounting base 24, thereby making the rigidity of the former relatively higher than that of the latter. Since the front side mounting base 24 with lower rigidity (with thinner board thickness) is deformed during assembly, the assembly stress is reduced. Furthermore, the assuring of strength relative to the load input is taken by the rear side mounting base 26 with higher rigidity (with thicker board thickness). In manufacturing the suspension member with the above structure, the casting direction of a lower mold 64 and an upper mold 66 is swung to one side (anticlockwise direction) by an original draft, thereby making the outside face 26B of the rear side mounting base 26 vertical from the beginning. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a cast suspension member that is formed by casting and includes a pair of mounting walls that are swingably mounted so as to sandwich an end portion of a suspension arm.

Conventionally, a suspension member is provided as a member for supporting a suspension arm and a steering gear box. In general, the suspension member is manufactured by press-molding a steel plate. Recently, however, there is an increasing need for manufacturing the suspension member by casting using an aluminum alloy or the like from the viewpoint of weight reduction.
JP-A-11-115796

  By the way, as a structure for mounting the suspension arm to the suspension member, a bush press-fitted to the tip of the arm is inserted and arranged so as to be sandwiched between a pair of mounting walls formed on the suspension member, and fixed with a bolt and a nut so as to be swingable. The structure to be taken may be taken.

  In this case, considering the input from the suspension arm to the suspension member, it is desirable to increase the strength by increasing the thickness of the pair of mounting walls.

  However, if the plate thickness of the pair of mounting walls is increased, there arises a problem that a relatively large mounting stress is generated when the suspension arm is assembled between the pair of mounting walls. More specifically, in order to allow the suspension arm to be attached to a pair of mounting walls, the distance between the opposing surfaces of the pair of mounting walls is set slightly larger than the axial length of the bush, and each mounting wall It is necessary to set a slight gap between the inner surface of the bush and the axial end surface of the bush.

  However, when the gap is set, when the bolt is tightened into the nut, the pair of mounting walls are deformed in the direction of approaching each other by the gap, but the mounting wall is taken into account in consideration of the input from the suspension arm. When the plate thickness is increased, the assembling stress generated at the deformed portion of the mounting wall increases as the plate thickness increases. In particular, in the case of a cast suspension member, since the fatigue strength is originally lower than that of a suspension member of a press-formed product, it is not preferable that the assembly stress is increased.

  As described above, in the case of a cast suspension member, securing the strength against the input from the suspension arm to the suspension member and preventing the increase of the assembly stress generated when the suspension arm is assembled to the suspension member are contradictory matters, and it is possible to achieve both. difficult.

  In view of the above facts, the present invention provides a cast suspension member capable of ensuring both strength against load input from the suspension arm to the suspension member and preventing increase in assembly stress generated when the suspension arm is assembled to the suspension member. The purpose is to obtain a manufacturing method.

  The method of manufacturing a cast suspension member according to the first aspect of the present invention is a method of manufacturing a cast suspension member having a pair of mounting walls that are swingably mounted with a fastener so as to sandwich the end of the suspension arm. And, the outer surface of one mounting wall is made parallel to the mounting surface at the end of the suspension arm by swinging the casting direction of the mold to one side by the original draft angle. It is said.

  The effect | action of this invention of Claim 1 is as follows.

  Since the outer surfaces of the pair of mounting walls in the suspension member serve as seating surfaces when fastened with fasteners, both sides need to be parallel to the mounting surface at the end of the suspension arm. Therefore, conventionally, the concave portion formed in the molding die is tapered in consideration of the draft angle, and the outer surface and the inner surface of the mounting wall are respectively cut by the secondary processing after the molding, thereby the suspension arm. The outer surface was parallel to the mounting surface at the end of the. In this case, the casting direction is vertical. In other words, conventionally, the manufacturing method requires secondary processing on all of the outer surfaces and the inner surfaces of the pair of mounting walls (total of four surfaces) instead of making the casting direction vertical.

  However, in the present invention, the outer surface of one mounting wall is made parallel to the mounting surface at the end of the suspension arm by swinging the casting direction of the mold to one side by the original draft angle. A surface parallel to the attachment surface at the end of the suspension arm can be obtained without performing secondary processing on the outer surface of at least one of the attachment walls. Accordingly, secondary processing is not necessary, so that the number of manufacturing steps can be reduced, which contributes to cost reduction.

  In addition, since the cast suspension member is manufactured as described above, the rigidity of one mounting wall is increased by using a method such as making the thickness of one mounting wall thicker than the thickness of the other mounting wall. It can be made relatively higher than the rigidity of the other mounting wall. By doing so, the load sharing for the input from the suspension arm changes. That is, the load burden on one mounting wall is greater than that on the other mounting wall. That is, the rigidity with respect to the input from the suspension arm can be ensured on one of the mounting walls.

  Conversely, when the suspension arm is assembled to the suspension member, one of the attachment walls having relatively high rigidity is hardly deformed, and the other attachment wall is relatively deformed in the assembling direction. Therefore, the assembly stress generated at the time of assembly is generated more largely on the other mounting wall side, but the other mounting wall is relatively "softer" than the one mounting wall, The generated assembly stress itself can be suppressed.

  From the above, when manufacturing a cast suspension member that can achieve both securing strength against load input from the suspension arm to the suspension member and preventing increase in assembly stress that occurs when the suspension arm is assembled to the suspension member, the manufacturing equipment can be greatly increased. There is no compelling change.

  As described above, the method for manufacturing a cast suspension member according to the first aspect of the present invention includes a pair of mounting walls that are swingably mounted with a fastener so as to sandwich the end of the suspension arm. In the suspension member manufacturing method, the outer surface of one mounting wall is made parallel to the mounting surface at the end of the suspension arm by swinging the casting direction of the mold to one side by the original draft angle. The secondary processing after casting of the suspension member can be reduced, and as a result, the manufacturing cost of the suspension member can be reduced and the manufacturing can be facilitated.

  According to the method for manufacturing a cast suspension member according to the first aspect of the present invention, since the cast suspension member is manufactured as described above, the thickness of one mounting wall is set to the thickness of the other mounting wall. A cast suspension member that can achieve both securing strength against load input from the suspension arm to the suspension member and preventing increase in assembly stress generated when the suspension arm is assembled to the suspension member. Can be manufactured without being forced to change the manufacturing equipment significantly.

  [First Embodiment]

  Hereinafter, the front suspension member 10 according to the first embodiment manufactured by the method for manufacturing a cast suspension member according to the present invention will be described with reference to FIGS.

  FIG. 4 is a perspective view showing the overall configuration of the front suspension member 10 according to the present embodiment, and FIG. 1 is an enlarged perspective view showing the main part of the front suspension member 10 as viewed from the back side. It is shown. 2 is a longitudinal sectional view showing the main part of the front suspension member 10, and FIG. 3 is a horizontal sectional view showing the main part of the front suspension member 10.

  As shown in FIG. 4, the front suspension member 10 includes a pair of front suspension front cross member 12 and front suspension rear cross member 14 arranged in parallel in the front-rear direction along the vehicle width direction, and the vehicle front-rear direction. A pair of front suspension side members 16 and 18 arranged in parallel to the left and right are configured, and the whole is formed in a well shape in plan view. The front suspension member 10 is formed by casting (aluminum die casting) using an aluminum alloy.

  A steering gear box 20 (see FIG. 3) is arranged on the front side of the front suspension front cross member 12 in the front suspension member 10 described above. A pair of front suspension arms 22 (see FIG. 2) is pivotally supported so as to be swingable.

  More specifically, as shown in FIGS. 1 to 3, a front mounting base 24 and a rear mounting base 26, which are integrally formed in a plate shape, are arranged in the front and rear sides at the front corner portion of the front suspension member 10. They are arranged in parallel. Bolt insertion holes 28 are formed on the outer corners of the front mounting base 24 and the rear mounting base 26 on the same axis, and the portion where the bolt insertion holes 28 are formed is for attaching the front suspension arm 22. These are a front arm mounting portion 30 and a rear arm mounting portion 32. A bush 34 (see FIG. 2) press-fitted into the inner end portion of the front suspension arm 22 is inserted between the front arm mounting portion 30 and the rear arm mounting portion 32 and can be swung by a bolt 36 and a nut 38. It is attached.

  Further, a gear box mounting portion 42 (see FIG. 3) for mounting the steering gear box 20 is integrally formed at a corner portion on the inner side of the front mounting base 24 described above, and the steering gear box 20 is mounted. Yes. A bolt insertion hole 43 is formed in the shaft core portion of the gear box mounting portion 42. The steering gear box 20 is fixed to a pair of left and right gear box mounting portions 42 by bolts 44 and nuts 46.

  Summarizing the configuration up to this point, in the cast suspension member structure according to the present embodiment, the front arm mounting portion 30 and the gear box mounting portion 42 of the front suspension member 10 are arranged in a standing state along the vehicle width direction. The plate-like front mounting base 24 is connected to each other in the vehicle width direction. Further, the front arm mounting portion 30 and the gear box mounting portion 42 described above are connected to each other by a metal (steel plate) plate (brace) 48 (see FIG. 2) formed in a strip shape by press molding. ing.

  Here, as shown in FIG. 2 and the like, in the present embodiment, the front mounting base 24 as a “pair of mounting walls” that pivotally support the end of the suspension arm 22 in a state where the end portion is sandwiched, and The rigidity ratio of the rear mounting base 26 is varied. More specifically, the thickness of the rear arm mounting portion 32 of the rear mounting base 26 located on the load acting direction side of the input F from the suspension arm 22 is determined by the thickness of the front arm mounting portion 30 of the front mounting base 24. By making it thicker than the plate thickness, the former rigidity is relatively higher than the latter rigidity.

  Further, as shown in FIG. 1, a pair of reinforcing ribs 50 are formed on the rear side of the rear mounting base 26 along a substantially plane perpendicular direction (substantially vehicle front-rear direction). The front end portions of these reinforcing ribs 50 are connected to the rear surface side of the rear mounting base 26, and function to support the rear mounting base 26 against input from the front suspension arm 22.

  Next, a method for manufacturing the front suspension member 10 by casting according to the present embodiment will be described, and the operation and effects of the present embodiment will be described through the description.

  FIG. 5 is a schematic diagram showing an outline of a conventional method for manufacturing a front suspension member, and FIG. 6 is a schematic diagram showing an outline of a method for manufacturing the front suspension member 10 according to the present embodiment. . Hereinafter, a method for manufacturing the front suspension member 10 according to the present embodiment will be described while comparing the two.

  Conventionally, as shown in FIG. 5A, the recess 54 that finally forms the rear mounting base 26 'is formed in an isosceles trapezoidal shape in the lower mold 56. The gap 60 formed when the upper die 58 is combined with the lower die 56 is for forming the front mounting base 24 '. Then, after casting, as shown in FIG. 5B, the lower die 56 and the upper die 58 are removed from each other in the direction separating from each other and the vertical direction as the casting direction (indicated by an arrow P). The product 62 (front suspension member) having the front mounting base 24 'and the rear mounting base 26' is obtained.

  In this case, the rear mounting base 26 'formed on the product 62 has an isosceles trapezoidal cross section. Further, the front mounting base 24 'is also inclined. Therefore, in order to enable fastening by the bolt 36 and the nut 38, the inner surface 24′A of the front mounting base 24 ′, the inner surface 26′A of the rear mounting base 26 ′, and the front mounting are performed by secondary processing. A total of four surfaces of the outer surface 24′B of the base 24 ′ and the outer surface 26′B of the rear mounting base 26 ′ are finished to be vertical surfaces. It is to be noted that the inner surface 24′A of the front mounting base 24 ′ and the inner surface 26′A of the rear mounting base 26 ′ need to be vertical surfaces because the mounting surface of the bush 34 of the front suspension arm 22 This is because of surface contact. In addition, the outer surface 24′B of the front mounting base 24 ′ and the outer surface 26′B of the rear mounting base 26 ′ need to be vertical surfaces when fastening the bolt 36 and the nut 38. This is because it becomes a seating surface.

  Therefore, according to the conventional manufacturing method, secondary processing is required for a total of four surfaces, which increases the number of manufacturing steps and costs.

  In contrast, in the method for manufacturing the front suspension member 12 according to the present embodiment, as shown in FIG. 6, the casting direction of the lower mold 64 and the upper mold 66 is set to one side by the original draft (in FIG. By swinging counterclockwise, the outer surface 26B of the rear mounting base 26 can be made vertical from the beginning. In this case, the casting direction is not the vertical direction, but the arrow Q direction swung in the counterclockwise direction in FIG. 5B by θ. Further, the inner surface 26A of the rear mounting base 26 becomes a total inclined surface of 2θ by the amount the casting direction is swung by θ.

  Thus, in the present embodiment, a surface parallel to the mounting surface of the bush 34 at the end of the front suspension arm 22 is obtained without performing secondary processing on the outer surface 26B of the rear mounting base 26. As a result, secondary processing is unnecessary. Therefore, the number of manufacturing steps can be reduced, which contributes to cost reduction. In addition, since parallel surfaces are formed from the beginning, there is no need to worry about machining accuracy. Accordingly, the front suspension member 10 including the front mounting base 24 and the rear mounting base 26 can be easily manufactured.

  Supplementally, in the case of the present embodiment, the inner surface 24A and the outer surface 24B of the front mounting base 24 can also be vertical surfaces, and thus the above-described effect can be obtained. However, in practice, the inner surface 24A of the front mounting base 24 is in contact with the mounting surface of the bush 34, so that secondary processing is performed for reasons such as increasing flatness. Further, the outer surface 24B of the front mounting base 24 is also subjected to secondary processing in the present embodiment because the plate 48 is mounted.

  Further supplementally, the state before the secondary processing is shown by a two-dot chain line so that the state of the presence or absence of the secondary processing is understood in FIG. The state before the secondary processing of the inner surface 24A and the outer surface 24B of the front mounting base 24 is two-dot chain lines a and b. The state before the secondary processing of the inner surface 26A of the rear mounting base 26 is a two-dot chain line c. Secondary processing is not performed on the outer surface 26 </ b> B of the rear mounting base 26.

  As described above, in the case of the cast suspension member structure according to the present embodiment, since the plate thickness of the rear mounting base 26 is made thicker than the plate thickness of the front mounting base 24, the load sharing for the input from the front suspension arm 22 is performed. Changes. That is, as shown in FIG. 2, the load load Fr of the rear mounting base 26 is larger than the load load Ff of the front mounting base 24 with respect to the input F from the front suspension arm 22 (Fr> Ff). That is, the rear mounting base 26 can ensure rigidity with respect to the input F from the front suspension arm 22.

  Conversely, when the front suspension arm 22 is assembled to the front mounting base 24 and the rear mounting base 26 of the front suspension member 10, the rear mounting base 26 having relatively high rigidity is hardly deformed, and the rigidity is relatively high. The lower front mounting base 24 is deformed in the assembly direction. Therefore, the assembly stress generated at the time of assembly is generated more largely on the front mounting base 24 side, but the front mounting base 24 is configured to be relatively softer than the rear mounting base 26, and thus generated. Assembling stress itself can be suppressed. The assembling stress is generated in the portion indicated by the arrow S in FIG. 2 and FIG.

  In summary, according to the cast suspension member structure of the present embodiment, the strength is secured against the load input from the front suspension arm 22 to the front suspension member 10 and the assembly that occurs when the front suspension arm 22 is assembled to the front suspension member 10. Both prevention of increase in stress can be achieved.

  Further, according to the method for manufacturing the cast suspension member according to the present embodiment, the secondary processing after the casting of the front suspension member 10 can be reduced, and the manufacturing cost and manufacturing of the front suspension member 10 are reduced accordingly. Simplification can be achieved.

  Furthermore, according to this manufacturing method, the casting direction is basically swung to one side by the amount corresponding to the conventional mold gradient, so the plate (although the shapes of the lower mold 64 and the upper mold 66 need to be changed). When manufacturing the front suspension member 10 having a pair of mounting walls (front mounting base 24 and rear mounting base 26) having different thicknesses, there is an advantage that the manufacturing equipment is not forced to be significantly changed.

  [Second Embodiment]

  Hereinafter, a second embodiment manufactured by the method for manufacturing a cast suspension member according to the present invention will be described with reference to FIGS. 7 and 8. In addition, about the same component as 1st Embodiment mentioned above, the same number is attached | subjected and the description is abbreviate | omitted.

  FIG. 7 shows a problem when the front suspension member 80 is manufactured by a conventional casting method. As shown in FIG. 7B, when cutting the runner 84 after casting from the gate 82, it is difficult to cut along the front surface of the front suspension member 80 without excess or deficiency. Cut the runner 84 along R. At this time, as shown in FIG. 7A, the uncut portion 86 remaining on the front suspension member 80 side is formed linearly on the lower edge of the front surface of the front suspension member 80. Although this uncut portion 86 overlaps with the gear box mounting portion 42, the adjacent portion of the gear box mounting portion 42 originally becomes a high stress portion 88 where stress concentration occurs, and therefore the uncut portion 86 is formed in the high stress portion 88. When they overlap, there is a problem that further stress concentration occurs.

  On the other hand, as shown in FIG. 8, the uncut portion 86 and the gear box mounting portion 42 of FIG. 7 overlap each other by arranging the uncut portion 90 obliquely so as to avoid the high stress portion 88. The increase in stress due to can be eliminated. That is, in the front suspension member 92 according to the present embodiment, stress concentration on the high stress portion 94 can be minimized.

  [Supplementary explanation of the embodiment]

  In each of the above-described embodiments, the method for manufacturing a cast suspension member according to the present invention is applied to the front suspension members 10 and 92. However, the present invention is not limited to this, and the present invention can also be applied to a rear suspension member. .

  In the first embodiment described above, the configuration is such that the reinforcing ribs 50 and 52 are set to increase the rigidity of the rear mounting base 26 while making the plate thickness of the rear mounting base 26 thicker than the plate thickness of the front mounting base 24. However, the present invention is not limited to this, and only one of them may be adopted. Further, which of the front mounting base 24 and the rear mounting base 26 is to be made highly rigid may be appropriately selected in relation to the input load. Conceptually, a configuration in which a high-rigidity part (thick part) and a low-rigidity part (thin part) are provided in order to change the load sharing. In addition, the configuration for imparting bending / softening includes configurations other than the method of changing the plate thickness and the method of setting the presence or absence of ribs or some of them. For example, an opening may be formed on one side and no opening may be formed on the other.

  Further, in the above-described second embodiment, the present invention is applied to the configuration in which the gear box mounting portion 42 is disposed on the front surface of the front suspension member 10, but the present invention is not limited to this, and various members (for example, a steering system) The present invention is applicable to mounting seats of members, suspension members, engine mounts, and the like.

It is an expansion perspective view which shows the principal part of the casting suspension member structure which concerns on 1st Embodiment seeing from a back side. FIG. 2 is a longitudinal sectional view of the front suspension member of FIG. 1 cut along a front suspension arm attachment site. FIG. 2 is a cross-sectional view of the front suspension member of FIG. 1 cut along a plane including both a front suspension arm attachment portion and a steering gear box attachment portion. FIG. 2 is a perspective view schematically showing an overall configuration of the front suspension member of FIG. 1. It is explanatory drawing for demonstrating the manufacturing method of the conventional casting suspension member. It is explanatory drawing for demonstrating the manufacturing method of the cast suspension member which concerns on this embodiment. It is related with explanatory drawing for demonstrating the problem by the conventional gate formation, (A) is a front view, (B) is a top view. It is related with explanatory drawing for demonstrating the structure of the casting suspension member structure which concerns on this embodiment, (A) is a front view, (B) is a perspective view.

Explanation of symbols

10 Front suspension member 20 Steering gear box 22 Front suspension arm 24 Front mounting base (one mounting wall)
26 Rear mounting base (the other mounting wall)
30 Front arm mounting portion 32 Rear arm mounting portion 34 Bush 36 Bolt (fastener)
38 Nut (fastener)
42 Gearbox mounting part (mounting seat)
50 Reinforcing ribs 64 Lower mold (molding mold)
66 Upper mold (molding mold)
84 Runway 90 Uncut portion 92 Front suspension member F Input

Claims (1)

A method for manufacturing a cast suspension member comprising a pair of mounting walls for swingably mounting with a fastener so as to sandwich an end portion of a suspension arm,
The outer surface of one mounting wall was made parallel to the mounting surface at the end of the suspension arm by swinging the casting direction of the mold to one side by the original draft angle,
A method for manufacturing a cast suspension member.

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