JP6428067B2 - Automotive parts - Google Patents

Description

  The present invention relates to an automobile member, and more particularly to an automobile suspension system member such as an automobile suspension arm such as a lower arm and a constituent member of an automobile subframe such as a cross member.

  Automobile suspensions (suspension systems) are maneuvered by reducing the impact input from the road surface via the tires and wheels to maintain a good riding comfort and ensuring the tire's ground contact during turning and acceleration / deceleration. It is a device that increases stability. The suspension is rotatably attached to the body, and a suspension arm that supports the hub supporting the tire and the wheel so as to move up and down, a spring that alleviates the impact from the road surface on the tire and the wheel, and a spring It is composed of a shock absorber that absorbs vibration, a stabilizer that is mounted as necessary, and that suppresses the difference in displacement between the left and right suspension arms, thereby suppressing the rolling of the vehicle body.

  Of these components of the suspension, the lower arm and the upper arm are used for the suspension arm according to the type such as the MacPherson strut type or the wishbone type.

  FIG. 7 is an explanatory view showing a general lower arm 1, FIG. 7 (a) shows the whole, and FIG. 7 (b) shows the collar attaching portion 1 a of the lower arm 1 in an enlarged manner. FIG. 8A is an explanatory view showing the arm body 2 of the lower arm 1, and FIG. 8B is an explanatory view showing the collar mounting portion 2a of the arm body 2 in an enlarged manner. Further, FIG. 9 is an explanatory view showing a welded portion between the arm body 2 and the collar 3.

The lower arm 1 includes an arm main body (hereinafter, also simply referred to as “main body”) 2 made of a metal (for example, steel) press-molded product, and a collar mounting portion 2 a that is a convex portion formed at a predetermined position of the main body 2. And a hollow and cylindrical collar 3 (referred to as “butt fillet weld” in this specification), and as shown in FIG. 8B and FIG. 2 and the collar 3, the concave outer shape line 2b formed in the front end opening of the collar mounting portion 2a is abutted against the outer peripheral curved surface 3a of the collar 3, and the butt fillet weld portion 4 is formed by arc welding or laser welding. By forming, it is welded.

  Further, in a vehicle type that generates high kinetic energy or a vehicle type that is particularly required to be quiet, it is becoming common for the suspension to be attached to the body shell via a subframe. FIG. 10 is an explanatory view showing an example of the subframe 5 attached to a body shell (not shown).

  As shown in FIG. 10, the cross member 6 constituting the sub-frame 5 has a concave outer shape line 7 b at the end 7 a in the longitudinal direction of the main body 7, and the outer shape line 7 b constitutes the sub-frame 5. The butt fillet weld 9 is formed by abutting against the outer peripheral curved surface 8a of the other pipe member 8 and butt fillet welding by arc welding or laser welding.

  Suspension members such as the lower arm 1 and the cross member 6 are repeatedly subjected to a load due to vibration during travel of the automobile. For this reason, the suspension system member is required to have sufficient fatigue strength in order to suppress fatigue failure. The fatigue strength of the suspension system members includes the characteristics of the main bodies 2 and 7, the chemical composition, the welding conditions (thermal history) of the welded portions 4 and 9, and the joint structure between the main bodies 2 and 7 and the welding counterpart materials 3 and 8. to be influenced.

  Until now, sufficient fatigue strength has been given to the welded portions 4 and 9 of the main body 2 and 7 of the suspension system member by the butt fillet welding described above. However, due to the recent promotion of weight reduction of automobiles, the thickness of the main body 2 and 7 of suspension system members has also been reduced. When a higher stress is repeatedly input to the suspension system member, there has been a concern that the butt fillet welds 4 and 9 will undergo fatigue failure.

  Further, in order to ensure the joining accuracy between the main bodies 2 and 7 and the welding counterpart materials 3 and 8, the concave outer shape lines 2b and 7b described above are aligned with the outer peripheral curved surfaces 3a and 8a of the welding counterpart materials 3 and 8. Although it is necessary to mold with high dimensional accuracy, if this dimensional accuracy cannot be ensured, the weldability between the concave outer shape lines 2b and 7b and the outer peripheral curved surfaces 3a and 8a is reduced, which causes fatigue failure. There is a fear. In order to ensure the dimensional accuracy of the concave outer shape line, it is necessary for the press-formed product that has been press-molded to go through a complicated trim process, and there is a concern about an increase in manufacturing cost.

  Patent Document 1 discloses an invention in which a collar attachment portion that is a convex portion is a separate part from the main body that is a press-formed product, and the collar attachment portion of the main body is attached after burring the two parts. According to the invention disclosed in Patent Document 1, the collar can be attached such that the collar attaching portion of the main body surrounds the outer periphery of the collar.

  Patent Document 2 discloses a ring member configured by welding after inserting a main body into a hole formed in a collar.

Japanese Patent No. 5363605 Utility Model Registration No. 2582424 Specification

  In the invention disclosed in Patent Document 1, since the collar mounting portion is a separate part from the main body that is a press-molded product, both the number of parts and the number of molding and welding processes increase, and an increase in manufacturing cost is inevitable. .

  Although the invention relating to the ring member disclosed in Patent Document 2 can be applied to a tension rod used as a component part of a suspension, it cannot be applied to a lower arm or a cross member whose body is considerably larger than a collar.

  The present invention has been made in view of these problems of the prior art, and the fatigue strength of the joint is greatly improved by simple means without increasing the number of parts and the number of forming and welding processes. It is an object of the present invention to provide an automobile suspension system member such as a member for an automobile subframe such as a suspension arm or a cross member of an automobile such as a lower arm.

  That is, the “automobile member” according to the present invention refers to a convex curved surface on at least a part of the outer surface among the above-described automobile suspension system members and various components mounted on the automobile body. And made of metal (for example, steel) welded (for example, arc welding or laser welding) to the first member at the opening of the first member (for example, steel) made of metal having a substantially groove-shaped opening. And a joint structure having a second member. For example, as such a joint structure, an opening of a structural member of an automobile which is a first member made of, for example, steel having a substantially groove-shaped opening and having a tensile strength of 590 MPa or more is used. The joint structure which has the structural member of the motor vehicle which has the closed cross-sectional shape which is the 2nd member made from steel with a tensile strength of 590 Mpa or more to be welded is illustrated.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors were able to obtain the knowledge A and B listed below and completed the present invention through further studies.

  (A) Instead of the conventional joint structure in which the main body and the collar are welded by butt fillet welding by abutting the concave outer shape line formed on the front end surface of the collar mounting portion against the outer peripheral curved surface of the collar, A flange having a curved surface that can follow the outer peripheral surface of the collar is formed on the collar mounting portion of the main body, and this flange and the outer peripheral surface of the collar are overlapped and overlapped by arc welding or laser welding (in this specification, By adopting a joint structure (referred to as “overlap fillet welding”), the fatigue strength of the welded portion between the main body and the collar can be significantly increased, and thereby the fatigue strength of the suspension arm can be increased.

  (B) Conventionally manufactured with great care, it is not affected by the shape accuracy of the outer line of the lower arm attachment part even during mass production. The strength can be increased.

The present invention is listed below.
(1) A top plate, two ridge lines that are continuous to the top plate, and a substantially groove-shaped opening formed by two vertical walls that are respectively continuous to the two ridge lines; the top plate, the two ridge lines, and the A metal first member having an outward flange continuous with each of the two vertical walls;
A second metal member having a convex curved surface on at least a part of the outer surface, the convex curved surface being disposed along the outward flange;
A suspension system member Ru and a fillet weld joining the end face and the convex curved surface of the outward flange,
Wherein the first member is a suspension arm body having a predetermined position the opening as the color mounting portion, said second member, for Ru color der vehicle is fillet welded lap to the color mounting portion Element.

(2) The automotive member according to (1) , wherein a width (Lf) of the outward flange is 2 mm or more and 20 mm or less.

(3) The automobile member according to (1) or (2) , wherein a radius of curvature (R) of the outward flange in a portion continuous with the vertical wall, the ridgeline, or the top plate is 10 mm or more and 100 mm or less.

(4) The automobile member according to any one of (1) to (3) , wherein the first member is a press-formed product of a high-tensile steel plate having a tensile strength of 590 MPa or more.

  Here, the tensile strength refers to the tensile strength obtained by the test method described in JIS Z 2241 (2011).

(5) The automobile member according to any one of (1) to (4) , wherein the member is a suspension arm.

  That is, the present invention specifically comprises a press-formed product of a high-tensile steel plate having a tensile strength of 590 MPa or more, and the top plate, two ridge lines continuous to the top plate, and two ridge lines continuous to the two ridge lines, respectively. A suspension arm body having a collar mounting portion, which is a substantially groove-shaped opening constituted by two vertical walls, in a predetermined position, and a hollow, at least part of the outer surface of which has a convex curved surface shape and arc welding to the collar mounting portion Alternatively, in a suspension arm including a collar to be laser-welded, an outward flange having a curved surface that can overlap the outer peripheral surface along the outer peripheral surface of the collar is provided in the opening, and an end surface of the flange is formed on the end surface of the collar. The suspension arm is characterized in that it is welded to the outer peripheral surface by overlapped fillet.

(6) The automobile member according to (5) , wherein the suspension arm is a lower arm or an upper arm.

  According to the present invention, an automotive member whose joint fatigue strength is greatly improved by simple means without increasing the number of parts and the number of molding and welding processes, such as a suspension arm or a cross member of an automobile such as a lower arm. An automobile suspension system member such as a constituent member of an automobile subframe can be provided.

FIG. 1A is an explanatory view showing a main body of a lower arm according to the present invention, FIG. 1B is an explanatory view showing an enlargement of a collar mounting portion in the main body. FIG. 2A is an explanatory view showing a modified example of the main body of the lower arm according to the present invention, and FIG. 2B is an explanatory view showing the collar mounting portion in the main body in an enlarged manner, and FIG. ) Is an explanatory view showing a molding material of a modification of the main body of the lower arm according to the present invention. Drawing 3 is an explanatory view showing the manufacturing method of the main part which passes through the 1st process-the 3rd process over time. FIG. 4A is an explanatory view showing a die and a punch used in the first step, and FIG. 4B is an explanatory view showing molding in one step. FIG. 5A is an explanatory view showing a die having a cam structure and a punch used in the second step, and FIG. 5B is an explanatory view showing molding in the second step. FIG. 6A is an explanatory view showing an upper die and a punch used in the third step, and FIG. 6B is an explanatory view showing molding in the third step. FIG. 7 is an explanatory view showing a general lower arm, FIG. 7 (a) shows the whole, and FIG. 7 (b) shows an enlarged collar mounting portion of the lower arm. FIG. 8A is an explanatory view showing the arm body of the lower arm, and FIG. 8B is an explanatory view showing the collar mounting portion of the arm body in an enlarged manner. FIG. 9 is an explanatory view showing a welded portion between the arm body and the collar. FIG. 10 is an explanatory view showing an example of a subframe attached to the body shell.

  The present invention will be described with reference to the accompanying drawings. In the following description, an example is given in which the automobile member according to the present invention is a suspension system member, and the suspension system member is a lower arm which is one of the suspension arms. However, the present invention is not limited to the lower arm, the upper arm, suspension-type automotive members such as a cross member that is a component of the subframe, automotive members such as a floor cross member and a front side member, Is a metal (for example, steel) first member having a convex curved surface on at least a part of an outer surface and a substantially groove-shaped opening among various components mounted on an automobile body and various parts mounted on an automobile. The present invention is similarly applied to a member for an automobile including a joint structure having a second member made of metal (for example, steel) that is welded (for example, arc welding or laser welding) to the first member at the opening of the member.

1. Lower Arm FIG. 1 (a) is an explanatory view showing a main body 11 of a lower arm 10 according to the present invention, FIG. 1 (b) is an enlarged view of a collar mounting portion 11a in the main body 11 and FIG. It is explanatory drawing.

The lower arm 10 includes a main body 11 and a collar 12.
The main body 11 is a press-formed product of a high-tensile steel plate having a tensile strength of 590 MPa or more. The main body 11 has a collar mounting portion 11a at a predetermined position. The collar attachment portion 11 a is a projecting opening formed in the main body 11. The collar attaching portion 11a is a substantially groove type constituted by a top plate 13, two ridge lines 14a, 14b continuous to the top plate 13, and two vertical walls 15a, 15b respectively continuous to the two ridge lines 14a, 14b. The cross-sectional shape is as follows.

  Like the known collar, the collar 12 has a hollow cylindrical shape for being rotatably attached to a predetermined mounting position, and is arc welded or laser welded to the collar attaching portion 11a of the main body 11, thereby 11 is welded.

  An outward flange 16 is formed in the opening, which is the collar mounting portion 11a of the main body 11, toward the outside of the opening. That is, the main body 11 is flange-up molded at the collar attachment portion 11a.

  The outward flange 16 has a curved surface 16 a that can overlap the outer peripheral surface 12 a along the outer peripheral surface 12 a of the collar 12. On the end face 16 b of the outward flange 16, a lap fillet weld portion 17 is formed by lap fillet welding with the outer peripheral surface 12 a of the collar 12.

  The outward flange 16 is continuously formed over the vertical walls 15a and 15b, the ridges 14a and 14b, and the top plate 13, but does not necessarily have to be continuous. However, by forming continuously, it is possible to improve the rigidity of the joint portion between the main body 11 and the collar 12 in addition to ensuring a sufficient joint length. The strength can be further improved.

  The width Lf of the outward flange 16 is required to secure a margin for lap fillet welding by arc welding or laser welding and to have a dimension smaller than that of the collar 12 so that the outward flange 16 does not protrude from the collar 12. Therefore, it is desirable that it is 2 mm or more and 20 mm or less.

  When the curvature radius R of the outward flange 16 in a portion continuous with the vertical walls 15a, 15b, the ridges 14a, 14b and the top plate 13 is small, that is, when the joint length is short, stress concentrates on the joint, and the outward flange 16 Fatigue failure is likely to occur regardless of the presence or absence and bonding method. Therefore, it is desirable that the radius of curvature R of the outward flange 16 is 10 mm or more. On the other hand, when the radius of curvature R is large, that is, when the joining length is long, sufficient fatigue strength can be ensured regardless of the presence of the outward flange 16 and the joining method. Therefore, the radius of curvature R of the outward flange 16 is desirably 100 mm or less.

  FIG. 2A is an explanatory view showing a modified example 18 of the main body of the lower arm 10 according to the present invention, and FIG. 2B is an explanatory view showing the collar attaching portion 18a in the main body 18 in an enlarged manner.

  Also in the modified example 18, the collar attaching portion 11a which is a projecting opening formed in the main body 18 includes a top plate 13, two ridge lines 14a and 14b continuous to the top plate 13, and two ridge lines 14a and 14b. Each has a substantially groove-shaped cross-sectional shape constituted by two continuous vertical walls 15a and 15b.

  An inward flange 19 directed inward of the opening is formed in the opening that is the collar mounting portion 18a of the main body 18. That is, the main body 18 is flange-down molded at the collar attachment portion 18a.

  The inward flange 19 has a curved surface 19 a that can overlap the outer peripheral surface 12 a along the outer peripheral surface 12 a of the collar 12. On the end face 19 b of the inward flange 19, a lap fillet weld is formed by lap fillet welding with the outer peripheral surface 12 a of the collar 12.

  Although the inward flange 19 is continuously formed over the vertical walls 15a and 15b, the ridge lines 14a and 14b, and the top plate 13, it does not necessarily have to be continuous. However, by forming continuously, in addition to ensuring a sufficient joint length, it becomes possible to improve the rigidity of the joint portion between the main body 18 and the collar 12, so that the fatigue strength at the lap fillet welded portion Can be further improved.

  As shown in FIGS. 1 and 2, in the present invention, instead of the conventional joint structure by butt fillet welding described above with reference to FIG. 9, the collar mounting portions 11a and 18a in the main bodies 11 and 18 of the lower arm 10 are externally attached. The direction flange 16 and the inward flange 19 are formed, and a joint structure is formed by overlapping fillet welding with the collar 12 through these flanges 16 and 19, so that the stress level input by vibration during traveling of the vehicle can be reduced. Thus, the fatigue strength of the welded portion between the main bodies 11 and 18 of the lower arm 10 and the collar 12 can be significantly improved as compared with the conventional case.

  Further, according to the present invention, the curved surfaces 16a and 19a of the outward flange 16 and the inward flange 19 and the outer peripheral surface 12a of the collar 12 are overlapped and brought into surface contact, so that the mounting accuracy of the collar 12 is easily ensured. The For this reason, the high dimensional accuracy requested | required of the conventional external shape lines 2b and 7b is eased. For this reason, since it becomes possible to attach the collar 12 with high dimensional accuracy to the collar attaching portions 11a and 18a of the main bodies 11 and 18 without increasing the number of manufacturing steps and manufacturing costs, there is a manufacturing variation at the time of mass production of the lower arm 10. The influence can be reduced, and the fatigue strength of the welded portion between the main bodies 11 and 18 of the lower arm 10 and the collar 12 to be mass-produced can be improved.

2. Manufacturing method of the main bodies 11 and 18 of the lower arm 10 Manufacturing (press molding) of the main bodies 11 and 18 of the lower arm 10, that is, flange-up molding of the main body 11 and flange-down molding of the main body 18 is not limited to a specific manufacturing method. However, any manufacturing method may be used. A suitable production method from the viewpoint of production cost and the like will be briefly described.

(1) Press molding method of the main body 11 FIG. 3 is an explanatory view showing the manufacturing method of the main body 11 through the first to third steps over time.
FIG. 4A is an explanatory view showing a die and a punch used in the first step, and FIG. 4B is an explanatory view showing molding in the first step. FIG. 5A is an explanatory view showing a die having a cam structure and a punch used in the second step, and FIG. 5B is an explanatory view showing molding in the second step. FIG. 6A is an explanatory view showing an upper die and a punch used in the third step, and FIG. 6B is an explanatory view showing molding in the third step.

[First step]
The blank 20 shown in FIGS. 3 and 4 (b) is press-molded (flange) using a die 21 having an inner surface shape shown in FIG. 4 (a) and a punch 22 having an outer surface shape shown in FIG. 4 (a). By performing (preforming), the flange preform 23 shown in FIGS. 3 and 4 (b) is manufactured.

[Second step]
3 and 5 (b), a die 24 having a cam structure having an inner surface shape shown in FIG. 5 (a) and configured to be pivotable in the direction of the arrow, and FIG. 5 (a). ) Is used to perform the press molding (offset bending), thereby producing the near end bent product 26 shown in FIGS. 3 and 5B.

[Third step]
3 and 6 (b), an upper die 27 having the outer shape shown in FIG. 6 (a) and a punch 28 having the outer shape shown in FIG. 6 (a) are used. The main body 11 shown in FIG. 3 and FIG. 6B is manufactured by performing press molding (color attachment portion determining push molding).

(2) Press Forming Method of Main Body 18 FIG. 2 (c) is an explanatory view showing a molding material 18b of Modification 18 of the main body of the lower arm 10 according to the present invention.

  As the molding material of the main body 18, the ridgelines 18b-1 and 18b-1 that exist in one direction (the direction of the double arrow in FIG. 2C) and both sides of the ridgelines 18b-1 and 18b-1 in the bending direction are provided. In addition, a workpiece 18b having a cross-sectional shape having a top plate 18b-2 and vertical walls 18b-3 and 18b-3 respectively continuous with the ridgeline is used. Bending (supporting the workpiece 18b from the inside of the cross section, pressing a part of one end of the ridges 18b-1 and 18b-1 in the plate thickness direction and bending the part in the cross section ( (Flange down molding) and the other longitudinal portions of the ridge lines 18b-1 and 18b-1 excluding this part, and the longitudinal directions of the top plate 18b-2 and the vertical walls 18b-3 and 18b-3, respectively. The other portions, the top plate 18b-2, and the respective end portions of the vertical walls 18b-3 and 18b-3 are pressed in the direction intersecting the plate thickness direction, and the other portions And the top plate 18b-2 and the vertical walls 18b-3 and 18b-3 are subjected to flange down molding so that the longitudinal ends of the ridgelines 18b-1 and 18b-1 are inward in the cross section. The formed ridge flange, top plate 18b-2, vertical wall 18b-3, 8b-3 of the longitudinal top plate flange formed in cross-section inwardly respectively on the top end of the can to produce a body 18 having an inward flange and the vertical wall flange is continuous.

  Thereby, the increase in the plate | board thickness of the ridgeline flange resulting from the shrinkage flange accompanying bending molding can be suppressed, As a result, generation | occurrence | production of the wrinkle of a ridgeline flange can be suppressed effectively. By this method, an increase in the plate thickness of the ridge line flange is suppressed. This is because the deformation state of the ridge line flange is reduced and the shear deformation field is reduced from the flange deformation field (strain ratio β (ε2 / ε1) <− 1: increased thickness). This is considered to be because the deformation element was changed to (strain ratio β (ε2 / ε1) ≈−1: no change in plate thickness).

  In this bending, a workpiece fixing tool that fixes and supports a region excluding the longitudinal end portion of the workpiece, and movable to the opposite side of the workpiece fixing tool with respect to the workpiece A bending apparatus provided with a bending blade tool is used. This bending blade tool has a protrusion that can press one portion of the end portion in the longitudinal direction of the ridge line portion of the workpiece in the plate thickness direction. By pressing one part of the longitudinal end of the ridge line part of the workpiece in the plate thickness direction by the protrusion, the difference in deformation speed between the protrusion and the other region pressed in the plate thickness direction in advance. Therefore, the shear deformation field element can be further increased.

  One part of the longitudinal end portion of the ridge line is preferably in a region having a substantially thickness width on both sides of the curved portion of the ridge line with the center in the circumferential direction as a center. It is further desirable to set the approximate center of the bending direction.

DESCRIPTION OF SYMBOLS 10 Lower arm 11 Main body 11a Collar attaching part 12 Collar 12a Outer peripheral surface 13 Top plate 14a, 14b Edge line 15a, 15b Vertical wall 16 Outward flange 16a Curved surface 16b End surface

Claims (6)

A top plate, two ridges continuous to the top plate, and a substantially groove-shaped opening formed by two vertical walls respectively continuing to the two ridge lines; the top plate, the two ridge lines, and the two vertical lines; A first metal member having an outward flange continuous with each of the walls;
A second metal member having a convex curved surface on at least a part of the outer surface, the convex curved surface being disposed along the outward flange;
A suspension system member Ru and a fillet weld joining the end face and the convex curved surface of the outward flange,
Wherein the first member is a suspension arm body having a predetermined position the opening as the color mounting portion, said second member, for Ru color der vehicle is fillet welded lap to the color mounting portion Element. The automotive member according to claim 1 , wherein a width of the outward flange is 2 mm or more and 20 mm or less. The automobile member according to claim 1 or 2 , wherein a radius of curvature of the outward flange in a portion continuous with the vertical wall, the ridgeline, or the top plate is 10 mm or more and 100 mm or less. The automotive member according to any one of claims 1 to 3, wherein the first member is a press-formed product of a high-tensile steel plate having a tensile strength of 590 MPa or more. The automotive member according to any one of claims 1 to 4 , wherein the member is a suspension arm. The automotive member according to claim 5 , wherein the suspension arm is a lower arm or an upper arm.

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