JP2004338706A - Sub frame for automobile, automobile and method for manufacturing sub frame for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sub frame and a method for manufacturing thereof for efficient manufacture with excellent dimensional accuracy. <P>SOLUTION: This sub frame S1 is provided with a pair of frame units 10 separately arranged to face each other. Each frame units 10 is constituted by respectively connecting an end member 15 having a joint part 16 to be connected to another member on both ends of an intermediate member 12 composed of a rod-like material by solid-state welding. The frame units 10 are respectively connected to both end parts of a connecting frame 30F disposed between the both frame units 10, 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an automobile subframe, an automobile, and a method of manufacturing an automobile subframe.

  In an automobile, a suspension device, a differential device, a steering device, an engine and the like are generally supported by subframes such as a front subframe and a rear subframe.

  This sub-frame is formed in various shapes according to the type of vehicle to which the sub-frame is mounted, and for example, a sub-frame formed in a substantially cross-girder shape is known. The sub-frame includes a pair of side members that are spaced apart from each other and that are opposed to each other, and a pair of cross members that are also spaced apart from each other. At both ends of each side member or each cross member, a joint portion (eg, a bracket portion for mounting a bush) connected to another member is provided.

  In the case where the entire subframe is integrally manufactured by casting, a large-sized die is required, which increases the manufacturing cost of the die. There was a disadvantage that the manufacturing cost was high.

Therefore, in order to solve such difficulties, there has been conventionally a method of dividing the subframe for each component, manufacturing each component individually, and then assembling and manufacturing the subframe by joining and integrating these components. It is known (for example, see Patent Documents 1-3).
JP-A-2002-337721 (page 4, FIG. 2-3) JP-A-2002-337722 (pages 4-5, FIG. 2-4) JP-A-2002-337723 (page 5, FIG. 2-3)

  However, conventionally, since the joining of the constituent members has been performed by fusion welding such as MIG, TIG, laser beam welding, etc., there is a disadvantage that the deformation accompanying the welding is large and the dimensional accuracy of the subframe is deteriorated after assembly. Was. In particular, in recent years, the requirements for the dimensional accuracy of the subframe have become strict, and for example, strict dimensional accuracy has been required for the pitch (interval) between the joints provided at both ends of the side member or the cross member. . For this reason, according to the conventional method of manufacturing a subframe, after the welding, the subframe must be subjected to straightening work, and the work efficiency of manufacturing the subframe is poor.

  The present invention has been made in view of the above-mentioned technical background, and an object of the present invention is to provide an automobile subframe having excellent dimensional accuracy and capable of being efficiently manufactured, an automobile including the same, and the subframe. It is to provide a manufacturing method of.

  In order to achieve the above object, the present invention provides the following means.

  [1] A subframe of an automobile, comprising a pair of frame units arranged to be spaced apart from each other and facing each other, and the two frame units are connected to each other via a connection frame disposed therebetween. Is configured such that end members having joints connected to other members are joined to both ends of an intermediate member made of a rod-shaped material by solid-phase joining using frictional heat, respectively. An automobile subframe characterized by the following.

  [2] In the frame unit, concave portions are respectively provided on both end surfaces of the intermediate member, and fitting convex portions provided on the end member are respectively fitted into concave portions on both end surfaces of the intermediate member. 2. The automobile sub-frame according to the preceding clause 1, wherein each of the fitting portions is subjected to friction stir welding as the solid-phase welding.

  [3] The sub-frame of the automobile according to the above item 1 or 2, wherein in the frame unit, outer peripheral surfaces of both end portions of the intermediate member are each formed in a circular cross section.

[4] In the frame unit,
The vehicle subframe according to any one of the preceding items 1 to 3, wherein both end portions of the intermediate member are formed straight, and a longitudinal intermediate portion of the intermediate member is bent.

  [5] The sub-frame for an automobile according to any one of the above items 1 to 4, wherein the intermediate member is formed of a rod-shaped hollow material.

  [6] The automobile subframe according to any one of the preceding items 1 to 5, wherein at least one of the intermediate member and the end member is made of light metal.

  [7] As the connection frame, a connection member connected to the frame unit is joined to both ends of a second intermediate member made of a rod-shaped material by a second solid-state joining using frictional heat, respectively. The vehicle subframe according to any one of the preceding items 1 to 6, wherein the configured connection frame unit is used.

  [8] The vehicle sub-frame according to the above item 7, wherein the frame units are respectively connected to both connecting members of the connecting frame unit by mechanical connecting means.

  [9] In the connection frame unit, second concave portions are provided on both end surfaces of the second intermediate member, respectively, and the second concave members are provided in the second concave portions on both end surfaces of the second intermediate member. 9. The automobile subframe according to the above item 7 or 8, wherein the second fitting projections are fitted respectively, and the respective solid portions are subjected to friction stir welding as the second solid-phase welding.

  [10] The vehicle subframe according to any one of the preceding items 7 to 9, wherein in the connection frame unit, outer peripheral surfaces of both end portions of the second intermediate member are each formed in a circular cross section.

  [11] In the connecting frame unit, any one of the preceding items 7 to 10, wherein both end portions of the second intermediate member are formed straight, and a longitudinal intermediate portion of the second intermediate member is bent. Sub-frame of the automobile according to the paragraph.

  [12] The sub-frame of an automobile according to any one of the above items 7 to 11, wherein the second intermediate member is made of a rod-shaped hollow material.

  [13] The automobile subframe according to any one of Items 7 to 12, wherein at least one of the second intermediate member and the connecting member is made of light metal.

  [14] An automobile equipped with the subframe according to any one of the above items 1 to 13.

  [15] A method for manufacturing a subframe of an automobile, comprising a pair of frame units arranged to be spaced apart from each other and facing each other, wherein the two frame units are connected to each other via a connection frame disposed therebetween. A frame unit is manufactured by joining end members having joints connected to other members to both ends of an intermediate member made of a rod-shaped material by solid-phase joining using frictional heat, respectively, to produce a frame unit. And a frame unit connecting step of connecting the frame units to both ends of a connecting frame, respectively.

  [16] In the manufacturing process of the frame unit, concave portions are provided on both end surfaces of the intermediate member, respectively, and one of the concave portions on both end surfaces of the intermediate member is provided on the end member. 16. The method for manufacturing a subframe for an automobile according to the preceding clause 15, wherein after the fitting projection is fitted, friction stir welding is performed on the fitting part as the solid-phase welding.

  [17] In the manufacturing process of the frame unit, a concave portion is provided on each of both end surfaces of the intermediate member, and the end member is provided in a concave portion of each of the both end surfaces of the intermediate member formed straight over the entire length. 16. The method of manufacturing a subframe for an automobile according to the preceding clause 15, wherein the fitting projections provided in the first and second fittings are fitted to each other, and friction stir welding is simultaneously performed on the two fitting portions as the solid phase welding.

  [18] The method for manufacturing a subframe of an automobile according to any one of the above [15] to [17], wherein outer peripheral surfaces of both end portions of the intermediate member are each formed in a circular cross section.

  [19] In the manufacturing process of the frame unit, the end members are respectively joined to both ends of the intermediate member formed straight over the entire length by the solid-phase joining, and then the length of the intermediate member is adjusted. 19. The method for manufacturing an automobile subframe according to any one of the above items 15 to 18, wherein only the middle part in the direction is bent.

  [20] The method for manufacturing a subframe of an automobile according to any one of the above items 15 to 19, wherein the intermediate member is formed of a rod-shaped hollow material.

  [21] The method for manufacturing a subframe of an automobile according to any one of the above items 15 to 20, wherein at least one of the intermediate member and the end member is made of light metal.

  [22] Further, a connecting member connected to the frame unit is joined to both ends of the second intermediate member made of a rod-shaped material by a second solid-state joining using frictional heat, thereby forming the connecting frame. 22. The method for manufacturing a subframe of an automobile according to any one of the above items 15 to 21, which includes a step of manufacturing a connection frame unit, which includes manufacturing a connection frame unit.

  [23] The method of manufacturing a subframe for an automobile according to the preceding item 22, wherein in the connecting step of the frame unit, the frame unit is connected to both connecting members of the connecting frame unit by mechanical connecting means.

  [24] In the manufacturing process of the connection frame unit, both end surfaces of the second intermediate member are provided with second concave portions, respectively, and one of the second concave portions on both end surfaces of the second intermediate member is provided. 24. The method for manufacturing a subframe of an automobile according to the preceding item 22 or 23, wherein after fitting protrusions provided on the connecting member are fitted, friction stir welding is performed on the fitting portion as the second solid-phase welding.

  [25] In the manufacturing process of the connection frame unit, second end portions are provided on both end surfaces of the second intermediate member, and both end surfaces of the second intermediate member formed straight over the entire length are provided. 24. The automobile according to the above item 22 or 23, wherein the fitting projections provided on the connecting member are fitted into the second recesses, respectively, and then the friction stir welding is simultaneously performed on the two fitting portions as the second solid-phase welding. Subframe manufacturing method.

  [26] The method for manufacturing a subframe of an automobile according to any one of the above items 21 to 25, wherein outer peripheral surfaces of both end portions of the second intermediate member are each formed in a circular cross section.

  [27] In the manufacturing process of the connection frame unit, the connection members are respectively joined to both end portions of the second intermediate member formed straight over the entire length by the second solid-state joining, 27. The method of manufacturing a subframe for an automobile according to any one of the above items 22 to 26, wherein only the intermediate portion in the length direction of the intermediate member is bent.

  [28] The method for manufacturing a subframe of an automobile according to any one of the aforementioned items 22 to 27, wherein the second intermediate member is formed of a rod-shaped hollow material.

  [29] The method of manufacturing a subframe for an automobile according to any one of the above items 22 to 28, wherein at least one of the second intermediate member and the connecting member is made of light metal.

  Next, the invention of each of the above items will be described.

  In the invention of [1], since the frame unit is formed by joining the end members having the joint portions to both ends of the intermediate member, the frame unit is suitable as the intermediate member depending on the vehicle type. By appropriately selecting the length, the pitch between the two joint portions can be easily set to a desired size. Therefore, parts can be shared for the end members. Similarly, by appropriately selecting an end member having an appropriate type of joint as an end member, it is possible to easily cope with various types of automobiles. Therefore, parts can be shared for the intermediate member.

  Moreover, in the manufacturing process of the frame unit, since the joining means for joining the end member to the end of the intermediate member is not fusion welding but solid-phase joining utilizing frictional heat, deformation due to joining is reduced. Almost no occurrence. Therefore, after joining, the frame unit has high dimensional accuracy with respect to the pitch (interval) between the joint portions. Therefore, at the time of manufacturing the sub-frame, it is not necessary to perform correction processing for improving the dimensional accuracy of the pitch between the two joint portions of the frame unit, or it is only necessary to perform simple correction processing. Therefore, the subframe can be manufactured efficiently, and the manufacturing cost of the subframe can be reduced.

  In the invention of [1], examples of the joint portion include a bracket portion for mounting a bush, a connection bolt insertion hole through which a connection bolt for connecting to another member (for example, a vehicle body) is inserted, and the like.

  Examples of solid-phase welding using frictional heat include friction stir welding and friction welding.

  Further, the intermediate member may be made of, for example, a rod-shaped solid material, or may be made of a rod-shaped hollow material as described later.

  Further, the end member may be made of, for example, an extruded material or a cut product thereof, or may be made of a cast product or a forged product.

  In the invention [2], the fitting protrusion provided on the end member is fitted into the recess on the end surface of the intermediate member, so that the end of the intermediate member is reinforced from the inside by the fitting protrusion. You. In this state, by performing friction stir welding on the fitting portion between the concave portion and the fitting convex portion, deformation of the end portion of the intermediate member, which may occur during friction stir welding, is prevented. Therefore, the intermediate member and the end member can be firmly joined and integrated.

  According to the invention as recited in the aforementioned Item [3], since the outer peripheral surface of the end of the intermediate member is formed in a circular cross section, the intermediate member and the end member can be securely and firmly joined and integrated.

  In the invention of [3], the cross-sectional shape of the outer peripheral surface of the end portion of the intermediate member is not limited to a perfect circular shape, but may be another circular shape (for example, an elliptical shape). .

  In the invention of [4], the intermediate portion of the intermediate member is bent, but since the both end portions of the intermediate member are formed straight, cracks in the joint that may occur due to bending of the intermediate member. Can be prevented.

  In the invention as recited in the aforementioned Item [5], since the intermediate member is made of a rod-shaped hollow material, the weight of the subframe can be reduced.

  In the invention [5], examples of the intermediate member include a rod-shaped extruded hollow member, a rod-shaped electric resistance welded tube member, and a rod-shaped hollow cast product. Further, the intermediate member is not limited to the cross-sectional shape, and may be a circular cross-section or a polygonal cross-section such as a square cross-section. Further, the intermediate member may have a hollow portion provided with a reinforcing rib portion.

  In the invention as recited in the aforementioned Item [6], since at least one of the intermediate member and the end member is made of light metal, the weight of the subframe can be reduced.

  In [6], when only one of the intermediate member and the end member is made of light metal, the other is desirably made of an iron-based material (for example, steel), but is not limited thereto. Not something.

  Examples of the light metal include aluminum, an aluminum alloy, and a magnesium alloy.

  According to the invention as recited in the aforementioned Item [7], the connecting frame unit is formed by joining the connecting members to both ends of the second intermediate member. Accordingly, by appropriately selecting the second intermediate member having an appropriate length, the pitch between the two connecting members can be easily set to a desired size. Therefore, parts can be shared for the connecting member. Similarly, by appropriately selecting an appropriate type of connecting member according to the vehicle type, it is possible to easily cope with various types of automobiles. Therefore, parts can be shared for the second intermediate member.

  In addition, in the manufacturing process of the connecting frame unit, the joining means for joining the connecting member to the end of the second intermediate member is not fusion welding but solid-phase joining utilizing frictional heat. ], Deformation due to welding hardly occurs. Therefore, after joining, the connection frame unit has high dimensional accuracy with respect to the pitch (interval) between the two connection members. Therefore, at the time of manufacturing the sub-frame, it is not necessary to perform a correcting process for improving the dimensional accuracy of the pitch between the two connecting members of the connecting frame unit, or it is only necessary to perform a simple correcting process. Therefore, the subframe can be manufactured more efficiently, and the manufacturing cost of the subframe can be further reduced.

  In the invention of [7], as the connecting member, a member having a connecting boss or a connecting concave portion for connecting to a frame unit (for example, an end member thereof), or connecting to a frame unit (for example, an end member thereof). Having a bolt insertion hole through which a bolt is inserted, a member having a joining bracket portion joined to a frame unit (for example, an intermediate member or an end member), and the like.

  Further, as the second solid-phase welding utilizing frictional heat, friction stir welding, friction welding and the like can be mentioned as in the above invention [1].

  Further, the second intermediate member may be made of, for example, a rod-shaped solid material, or may be made of a rod-shaped hollow material as described later.

  The second end member may be made of, for example, an extruded material or a cut product thereof, or may be made of a cast product or a forged product.

  In the invention as recited in the aforementioned Item [8], the frame unit is mechanically coupled to the coupling member of the coupling frame unit. In the connecting step of the frame unit, the connecting means for connecting the frame unit to the connecting member of the connecting frame unit is not a fusion welding but a mechanical connection, so that deformation due to welding does not occur. Therefore, after the connection, the sub-frame has high dimensional accuracy for the interval between the pair of frame units. Therefore, at the time of manufacturing the sub-frame, it is not necessary to perform a correcting process for improving the dimensional accuracy of the interval between the two frame units, or it is only necessary to perform a simple correcting process. Therefore, the subframe can be manufactured more efficiently, and the manufacturing cost of the subframe can be further reduced.

  In the invention as recited in the aforementioned Item [8], examples of the mechanical connection include connection by press-fitting the connection boss into the connection recess, bolting, rivet fastening, and swaging.

  According to the invention as recited in the aforementioned Item [9], similarly to the invention as described in the above [2], deformation of the end portion of the second intermediate member, which may occur during friction stir welding, is prevented. Therefore, the second intermediate member and the connecting member can be firmly joined and integrated.

  According to the invention [10], similarly to the invention [3], the second intermediate member and the connecting member can be securely and integrally joined.

  In the invention of [10], the cross-sectional shape of the outer peripheral surface of the end portion of the second intermediate member is not limited to a perfect circular shape, but may be another circular shape (for example, an elliptical shape). Is also good.

  According to the invention as recited in the aforementioned Item [11], similarly to the invention as described in the above [4], it is possible to prevent the joint from cracking, which may be caused by the bending of the second intermediate member.

  According to the invention as recited in the aforementioned Item [12], since the second intermediate member is made of a rod-shaped hollow material, the weight of the subframe can be reduced.

  In the invention as recited in the aforementioned Item [12], examples of the second intermediate member include a rod-shaped extruded hollow member, a rod-shaped electric resistance welded tube member, and a rod-shaped hollow cast product. Further, the second intermediate member is not limited to the cross-sectional shape, and may have a circular cross-section or a polygonal cross-section such as a quadrangular cross-section. Further, the second intermediate member may have a hollow portion provided with a reinforcing rib portion.

  According to the invention as recited in the aforementioned Item [13], since at least one of the second intermediate member and the connecting member is made of light metal, the weight of the subframe can be reduced.

  In [13], when only one of the second intermediate member and the connecting member is made of light metal, the other is preferably made of an iron-based material (for example, steel), but is not limited thereto. It is not done.

  Examples of the light metal include aluminum, an aluminum alloy, and a magnesium alloy.

  According to the invention as recited in the aforementioned Item [14], since the automobile is equipped with the subframe according to any one of the first to thirteenth aspects, the production cost of the subframe of the automobile can be reduced.

  According to the invention as recited in the aforementioned Item [15], similarly to the invention as described in the above [1], parts can be shared for the intermediate member and the end member, and the subframe can be manufactured efficiently.

  According to the invention as recited in the aforementioned Item [16], similarly to the invention as described in the above [2], it is possible to prevent the deformation of the end portion of the intermediate member which may occur during the friction stir welding, so that the intermediate member and the end member are firmly connected. Can be joined and integrated.

  According to the invention as recited in the aforementioned Item [17], the frame unit of the sub-frame can be manufactured efficiently by simultaneously performing the friction stir welding on the both fitting portions.

  According to the invention as recited in the aforementioned Item [18], similarly to the invention as described in the above [3], the intermediate member and the end member can be securely and firmly joined and integrated.

  According to the invention as recited in the aforementioned Item [19], by bending only the intermediate portion of the intermediate member formed straight over the entire length, a joint portion that may be generated due to the bending of the intermediate member as in the case of the above [4]. Cracks can be prevented.

  According to the invention as recited in the aforementioned Item [20], similarly to the invention as described in the above [5], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [21], similarly to the invention as described in the above [6], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [22], similarly to the invention as described in the above [7], the second intermediate member and the connecting member can be used as common components, and the subframe can be manufactured more efficiently.

  According to the invention as recited in the aforementioned Item [23], similarly to the invention as described in the aforementioned Item [8], a subframe having excellent dimensional accuracy can be manufactured more efficiently.

  According to the invention as recited in the aforementioned Item [24], similarly to the invention as described in the above [9], the second intermediate member and the connecting member can be firmly joined and integrated.

  According to the invention as recited in the aforementioned Item [25], by simultaneously applying friction stir welding to both fitting portions, the connecting frame unit of the sub-frame can be manufactured efficiently.

  According to the invention as recited in the aforementioned Item [26], similarly to the invention as described in the above [10], the second intermediate member and the connecting member can be securely and integrally joined.

  According to the invention as recited in the aforementioned Item [27], similarly to the invention as described in the above [11], it is possible to prevent the joint portion from cracking which may be caused by the bending of the second intermediate member.

  According to the invention as recited in the aforementioned Item [28], similarly to the invention as described in the above [12], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [29], it is possible to reduce the weight of the subframe as in the invention as described in the above [13].

  The present invention has the following effects.

  According to the invention as recited in the aforementioned Item [1], the frame unit is formed by joining the end members having the joints to both ends of the intermediate member, respectively. Parts can be shared.

  In addition, in the manufacturing process of the frame unit, the joining means for joining the end member to the end of the intermediate member is not fusion welding but solid-phase joining using frictional heat, so that deformation due to joining is almost impossible. Does not occur. Therefore, after joining, the frame unit has high dimensional accuracy with respect to the pitch between the two joint portions. Therefore, at the time of manufacturing the sub-frame, it is not necessary to perform correction processing for improving the dimensional accuracy of the pitch between the two joint portions of the frame unit, or it is only necessary to perform simple correction processing. Therefore, the subframe can be manufactured efficiently, and the manufacturing cost of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [2], it is possible to prevent the deformation of the end portion of the intermediate member which may occur during the friction stir welding, so that the intermediate member and the end member can be firmly joined and integrated. .

  According to the invention as recited in the aforementioned Item [3], the intermediate member and the end member can be securely and firmly joined and integrated.

  According to the invention as recited in the aforementioned Item [4], it is possible to prevent the joint from cracking, which may occur with the bending of the intermediate member.

  According to the invention as recited in the aforementioned Item [5], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [6], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [7], components can be shared for the second intermediate member and the connecting member. Moreover, at the time of manufacturing the sub-frame, it is not necessary to perform a straightening process to improve the dimensional accuracy of the pitch between the two connecting members of the connecting frame unit, or it is sufficient to perform only a simple straightening process. It can be manufactured more efficiently.

  According to the invention as recited in the aforementioned Item [8], at the time of manufacturing the sub-frame, it is not necessary to perform a straightening process for improving the dimensional accuracy of the interval between the two frame units, or it is sufficient to perform only a simple straightening process. The subframe can be manufactured more efficiently.

  According to the invention as recited in the aforementioned Item [9], it is possible to prevent the deformation of the end portion of the second intermediate member, which may occur at the time of friction stir welding. Therefore, the second intermediate member and the connecting member are firmly joined and integrated. be able to.

  According to the invention as recited in the aforementioned Item [10], the second intermediate member and the connecting member can be securely and firmly integrated.

  According to the invention as recited in the aforementioned Item [11], it is possible to prevent the joint from cracking, which may occur with the bending of the second intermediate member.

  According to the invention as recited in the aforementioned Item [12], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [13], the weight of the subframe can be reduced.

  According to the invention as recited in the aforementioned Item [14], it is possible to reduce the manufacturing cost of the subframe of the automobile.

  According to the invention as recited in the aforementioned Item [15], similarly to the invention as described in the aforementioned Item [1], parts can be shared for the intermediate member and the end member, and the subframe can be manufactured efficiently.

  According to the invention [16], the same effects as those of the invention [2] can be obtained.

  According to the invention as recited in the aforementioned Item [17], the frame unit of the sub-frame can be manufactured efficiently.

  According to the invention as recited in the aforementioned Item [18], the same effects as those of the invention as described in the above [3] can be obtained.

  According to the invention as recited in the aforementioned Item [19], the same effects as those of the invention as described in the above [4] can be obtained.

  According to the invention as recited in the aforementioned Item [20], effects similar to those of the invention as described in the above [5] can be obtained.

  According to the invention as recited in the aforementioned Item [21], the same effects as those of the invention as described in the above [6] can be obtained.

  According to the invention as recited in the aforementioned Item [22], similarly to the invention as described in the above [7], the second intermediate member and the connecting member can be used as common components, and the subframe can be manufactured more efficiently.

  According to the invention as recited in the aforementioned Item [23], the same effects as those of the invention as described in the above [8] can be obtained.

  According to the invention [24], the same effect as the invention [9] can be obtained.

  According to the invention as recited in the aforementioned Item [25], the connection frame unit of the subframe can be manufactured efficiently.

  According to the invention as recited in the aforementioned Item [26], effects similar to those of the invention as described in the above [10] can be obtained.

  According to the invention as recited in the aforementioned Item [27], effects similar to those of the invention as described in the above [11] can be obtained.

  According to the invention as recited in the aforementioned Item [28], the same effects as those of the invention as described in the above [12] can be obtained.

  According to the invention as recited in the aforementioned Item [29], the same effects as those of the invention as described in the above [13] can be obtained.

  Next, some preferred embodiments of the present invention will be described with reference to the drawings.

  1 to 4 are views for explaining a subframe and a method of manufacturing the subframe according to the first embodiment of the present invention.

  In FIG. 1, (S1) is a subframe according to the first embodiment. This sub-frame (S1) is used as a rear sub-frame or a front sub-frame in an automobile (not shown) such as an FF vehicle or an FR vehicle, and is arranged substantially horizontally when mounted on the automobile. Things.

  As shown in FIG. 1, the sub-frame (S1) has a substantially cross-girder shape (including a substantially rectangular shape) in plan view, and extends in the front-rear direction of the vehicle body, is spaced apart from each other, and faces each other. A pair of left and right side members (11) and (11) and a pair of front and rear cross members (31) and (31) extending in the left-right direction of the vehicle body and spaced apart from each other and opposed to each other. Have. Each cross member (31) is for connecting the pair of side members (11) and (11) to each other, and is arranged between both side members (11) and (11). The pair of side members (11) and (11) are connected to each other via the cross member (31).

  In the subframe (S1) of the first embodiment, the pair of side members (11) and (11) correspond to the pair of frame units (10) and (10), and the pair of cross members (31). (31) corresponds to the pair of connecting frames (30F) and (30F). Further, in the sub-frame (S1), the connection frame unit (30) is used as the connection frame (30F).

  Each frame unit (10) (that is, each side member (11)) has an intermediate member (12) (hereinafter, referred to as a "first intermediate member") and two end portions formed to have the same shape and size. (15) and (15).

  The first intermediate member (12) is formed of a metal rod-shaped tubular material having a predetermined length as a rod-shaped hollow material, and has a hollow portion (13) provided in a penetrating shape in the length direction. Therefore, concave portions (13a) (hereinafter, referred to as “first concave portions”) are formed on both end surfaces of the first intermediate member (12). The outer peripheral surfaces of at least both ends of the first intermediate member (12) are each formed in a circular cross section.

  In the first embodiment, the first intermediate member (12) is made of, for example, an extruded tube or an electric resistance welded tube of aluminum or an aluminum alloy.

  The end member (15) has a bush mounting tubular bracket (17) as a joint (16). The bracket portion (17) has a bush mounting hole (17a), and a bush (B) having a rubber elastic portion is mounted in the bush mounting hole (17a) as shown in FIG. Is done. The bracket portion (17) is connected to a vehicle body (not shown) as another member via a bush (B) mounted in the bush mounting hole (17a).

  Further, as shown in FIGS. 2A and 2B, the end member (15) has a connecting portion (18) having a circular cross section, and further has a center of an end face of the connecting portion (18). A fitting projection (19) having a circular cross section (hereinafter, referred to as a “first fitting projection”) is integrally formed with the portion. The diameter of the outer peripheral surface of the connecting portion (18) is set to be the same as the diameter (that is, the outer diameter) of the outer peripheral surface of the end of the first intermediate member (12). The diameter of the first fitting projection (19) is equal to or slightly larger than the diameter of the inner peripheral surface of the end of the first intermediate member (12) (that is, the inner diameter or the diameter of the first recess (13a)). Dimensions are set.

  In the first embodiment, the end member (12) is made of a cut product of an extruded material of aluminum or an aluminum alloy. In the present invention, the end member (12) may be made of, for example, a cast product or a forged product.

  The first fitting projections (19) of the end member (15) are fitted into the first recesses (13a) on both end faces of the first intermediate member (12), respectively. (20) is subjected to friction stir welding as solid-phase welding utilizing frictional heat (hereinafter, referred to as "first solid-phase welding"), so that both ends of the first intermediate member (12) have end portions. The members (15) are respectively joined. In FIG. 1, (J1) is a joint formed by friction stir welding (that is, a friction stir weld) formed in the fitting portion (20). Thus, each frame unit (10) is configured.

  As shown in FIG. 1, each connecting frame unit (30) (that is, each cross member (31)) has a second intermediate member (32) and two connecting members (35) formed in the same shape and the same size. ) (35).

  The second intermediate member (32) is made of a metal rod-shaped tubular material having a predetermined length as a rod-shaped hollow material, and has a hollow portion (33) provided in a lengthwise manner and penetrating therethrough. Therefore, concave portions (33a) are formed on both end surfaces of the second intermediate member (32). The outer peripheral surfaces of at least both ends of the second intermediate member (32) are each formed in a circular cross section.

  In the first embodiment, the second intermediate member (32) is made of, for example, an extruded tube or an electric resistance welded tube of aluminum or an aluminum alloy.

  The connecting member (35) has a connecting boss (37) having a circular cross section (see FIG. 4A). The connection boss (37) is connected to the end member (15) by being pressed into a connection recess (21) provided in the end member (15) of the frame unit (10). .

  Further, the connecting member (35) has a flange portion (38) as shown in FIG. 3, and further has a second fitting convex having a circular cross section at the center of the end face of the flange portion (38). The part (39) is integrally formed. The diameter of the outer peripheral surface of the flange portion (38) is set to be the same as the diameter (that is, the outer diameter) of the outer peripheral surface of the end portion of the second intermediate member (32). The diameter of the second fitting projection (39) is equal to or slightly larger than the diameter of the inner peripheral surface of the end of the second intermediate member (32) (that is, the inner diameter or the diameter of the second recess (33a)). Dimensions are set.

  In the first embodiment, the connecting member (35) is made of a cut product of an extruded material of aluminum or an aluminum alloy. In the present invention, the connecting member (35) may be made of, for example, a cast product or a forged product.

  Then, the second fitting projections (39) of the connecting member (35) are fitted into the second recesses (33a) on both end surfaces of the second intermediate member (32), respectively, and the fitting portions ( By performing friction stir welding as the second solid-phase welding utilizing frictional heat in 40), the connecting members (35) are respectively joined to both ends of the second intermediate member (32). In FIG. 1, (J1) is a joint formed by friction stir welding (that is, a friction stir weld) formed in the fitting portion (40). Thus, each connection frame unit (30) is configured.

  Further, in the sub-frame (S1), as shown in FIG. 1, the connection boss (37) of the connection frame unit (30) is connected to the connection recess ( 21). Further, in this state, the end member (15) is connected to the connecting member (35) by fusion welding (MIG, TIG, laser beam welding, etc.) or solid-phase welding utilizing frictional heat (friction stir welding, friction welding, etc.). Are joined. In FIG. 1, (J2) is a joining portion where the end member (15) is joined to the connecting member (35). In this way, the frame units (10) are connected to both ends of the connection frame unit (30), respectively.

  In the sub-frame (S1), an arm (not shown) connection bracket (50) is fusion-welded (MIG, TIG, laser beam welding) to the first intermediate member (12) of each frame unit (10). ) Or solid-phase welding utilizing frictional heat (friction stir welding, friction welding, etc.). Similarly, the second intermediate member (32) of each connection frame unit (30) has two arms (not shown) connecting brackets (50) (50) which are solid-phase welded or frictionally heated. Joined by joining.

  Next, a method for manufacturing the subframe (S1) will be described.

  First, a manufacturing process of the frame unit (10) for manufacturing a pair of frame units (10) and (10), and a manufacturing process of the connecting frame unit (30) for manufacturing a pair of connecting frame units (30) and (30), respectively. The manufacturing process is performed individually. Next, a frame unit (10) connection step of connecting the frame units (10) to both ends of the connection frame unit (30) is performed.

  The manufacturing process of the frame unit (10), the manufacturing process of the connecting frame unit (30), and the connecting process of the frame unit (10) will be described below.

[Production process of frame unit (10)]
First, as shown in FIGS. 2 (a) and 2 (b), a first intermediate member (12) made of a rod-shaped tubular material formed straight over the entire length is prepared. The first intermediate member (12) is formed in a perfect circular cross section and has a predetermined length.

  In addition, two end members (15) having the bush mounting bracket (17), the connecting portion (18), and the first fitting protrusion (19) are prepared.

  Next, the first fitting projections (19) of the end member (15) are fitted tightly or slightly tightly into the recesses (13a) on both end surfaces of the first intermediate member (12). In this fitting state, the outer peripheral surface of the end of the first intermediate member (12) and the outer peripheral surface of the connecting portion (18) of the end member (15) are flush with each other.

  Next, friction stir welding is simultaneously performed on the two fitting portions (20) and (20) as first solid-phase welding. Thereby, the end members (15) are respectively joined to both ends of the first intermediate member (12).

  The joining operation will be described as follows.

  In FIG. 2B, reference numeral (60) denotes a welding tool for friction stir welding. The joining tool (60) has a rotatable large-diameter shoulder portion (61), and a small-diameter pin-shaped probe (62) protruding from the shoulder portion (61). Two welding tools (60) are prepared.

  The shoulder (61) and the probe (62) of each joining tool (60) are rotated. Then, the probe (62) of the one joining tool (60) is connected to the concave portion (13a) on one end surface of the first intermediate member (12) and the first fitting convex portion (19) of the one end member (15). And the shoulder (61) of the joining tool (60) is connected to the connecting portion (18) of the outer peripheral surface of the first intermediate member (12) and the end member (15). ) And the probe (62) of the other joining tool (60) is connected to the concave portion (13a) of the other end surface of the first intermediate member (12) and the probe (62) of the other end member (15). 1 While being embedded in the fitting portion (20) with the fitting projection (19), the shoulder (61) of the joining tool (60) is connected to the outer peripheral surface of the first intermediate member (12) and the end member. Press against the outer peripheral surface of the connecting portion (18) of (15). In this state, the positions of the probes (62) and (62) of both the joining tools (60) and (60) are fixed, and each fitting portion (20) passes through the corresponding probe (62) sequentially. The first intermediate member (12) is rotated about its axis. With this rotation operation, friction stir welding is performed on the fitting portion (20). In this way, the friction stir welding is simultaneously performed on both the fitting portions (20), (20), and the end members (15) are respectively joined to both ends of the first intermediate member (12).

  In the first embodiment, since the first intermediate member (12) is formed straight over the entire length, the first intermediate member (12) is rotated about the axis thereof, whereby the first intermediate member (12) is rotated. The joining operation of joining the end members (15) to both ends of the member (12) can be performed simultaneously. Therefore, the frame unit (10) can be manufactured efficiently.

  Further, in a state where the first fitting projection (19) of the end member (15) is fitted to the first recess (13a) of the end face of the first intermediate member (12), the fitting portion (20) Is subjected to friction stir welding, the end of the first intermediate member (12) is reinforced by the first fitting projection (19) from the inside during friction stir welding. Therefore, it is possible to prevent deformation of the end of the first intermediate member (12) that may occur during friction stir welding. Therefore, the first intermediate member (12) and the end member (15) can be firmly joined and integrated, and the strength reliability of the frame unit (10) is improved.

  Further, since the outer peripheral surface of the end portion of the first intermediate member (12) is formed in a circular cross section, the first intermediate member (12) and the end member (15) are securely and firmly joined and integrated. be able to.

  Next, if necessary, only the middle portion in the length direction of the first intermediate member (12) is bent by a bending process such as a press bending process or crushed and deformed by a crushing process.

  Next, aging (for example, the condition: 200 ° C. × 4 hours) is performed on the frame unit (10) as necessary. By doing so, it is possible to recover the strength reduced by the joining.

  Through the above steps, the frame unit (10) is manufactured.

[Manufacturing process of connecting frame unit (30)]
First, as shown in FIG. 3, a second intermediate member (32) made of a rod-shaped tubular material formed straight over the entire length is prepared. The second intermediate member (32) is formed in a perfect circular cross section (see FIG. 4 (c)), and has a predetermined length.

  Further, two connection members (35) each having a connection boss (37), a flange (38), and a second fitting projection (39) are prepared.

  Next, as shown in FIG. 3, the second fitting projections (39) of the connecting member (35) are tightly or slightly tight in the second recesses (33a) on both end surfaces of the second intermediate member (32). Fit. In this fitted state, the outer peripheral surface of the end of the second intermediate member (32) and the outer peripheral surface of the flange portion (38) of the connecting member (35) are flush with each other.

  Next, friction stir welding is simultaneously applied to the two fitting portions (40) as a second solid-phase welding utilizing frictional heat. Thereby, the connecting members (35) and (35) are fitted to both ends of the second intermediate portion (32), respectively.

  This joining operation is performed in the same manner as the joining operation described above, and redundant description will be omitted. In the figure, reference numeral (60) denotes a welding tool for friction stir welding used in this welding.

  In this joining operation, since the second intermediate member (32) is formed straight over the entire length, by rotating the second intermediate member (32) about its axis, the second intermediate member (32) is rotated. ) Can be simultaneously performed to join the connecting members (35) to both ends. Therefore, the connection frame unit (30) can be manufactured efficiently.

  Further, in a state where the second fitting projection (39) of the connecting member (35) is fitted into the second recess (33a) on the end face of the second intermediate member (32), the fitting portion (40) Since the friction stir welding is performed, it is possible to prevent the deformation of the end of the second intermediate member (32) which may occur during the friction stir welding. Therefore, the second intermediate member (32) and the connecting member (35) can be firmly joined and integrated, and the strength reliability of the connecting frame unit (30) is improved.

  Also, since the outer peripheral surface of the end of the second intermediate member (32) is formed in a circular cross section, the second intermediate member (32) and the connecting member (35) can be securely and firmly integrated. Can be.

  Thereafter, as shown in FIG. 4 (a), only the longitudinally intermediate portion (region b in FIG. 4 (a)) of the second intermediate member (32) of the connection frame unit (30) is subjected to press bending or the like. It is bent upward into a substantially gate shape by bending. Further, only the intermediate portion of the second intermediate member (32) is crushed by crushing, and is deformed into a substantially trapezoidal cross section as shown in FIG. 4B. Thereby, the intermediate portion of the second intermediate member (32) is formed wider than both end portions in plan view as shown in FIG. On the other hand, both ends (region a in FIG. 4A) of the second intermediate member (32) maintain a straight shape without performing the bending and the crushing. By doing so, it is possible to prevent the joint (J1) from cracking, which may occur with the bending of the second intermediate member (32).

  Next, aging (for example, the condition: 200 ° C. × 4 hours) is performed on the connection frame unit (30) as necessary. By doing so, it is possible to recover the strength reduced by the joining.

  In the first embodiment, the axes of both ends of the second intermediate member (32) are on the same straight line after being subjected to the bending process. Therefore, in the second intermediate member (32), after the bending process is performed, the joining operation of joining the end members (35) to both ends of the second intermediate member (32) is performed in the same manner as described above. Can be performed simultaneously.

  Through the above steps, the connection frame unit (30) is manufactured.

[Connection process of frame unit (10)]
First, a pair of frame units (10) and (10) and a pair of connection frame units (30) and (30) are prepared. Next, as shown in FIG. 1, one connection boss (37) of the connection frame unit (30) is pressed into the connection recess (21) of the end member (15) of the corresponding frame unit (10). Accordingly, the frame unit (10) is connected to one end of the connection frame unit (30) by press-fitting (ie, mechanically connecting) the connection boss (37) to the connection recess (21). Similarly, the other connection boss portion (37) of the connection frame unit (30) is pressed into the connection recess (21) of the end member (15) of the corresponding frame unit (10). Thereby, the frame unit (10) is connected to the other end of the connection frame unit (30). In this manner, the frame units (10) are connected to both ends of the connection frame unit (30), respectively, and assembled in a substantially cross-girder shape in plan view.

  Next, the end member (15) of the frame unit (10) is connected to the connecting member (35) of the connecting frame unit (30) by fusion welding (MIG, TIG, laser beam welding, or the like) or solid-phase joining using frictional heat ( Joining (the joint J2) by friction stir welding, friction welding, or the like. This improves the connection strength between the connection frame unit (30) and the frame unit (10).

  Through the above connecting step, the pair of frame units (10) is connected to each other via the connecting frame unit (30).

  Next, the arm connection bracket (50) is joined to the frame unit (10) or the connection frame unit (30). The joining of the bracket (50) may be performed before the connecting step of the frame unit (10).

  Through the above steps, the subframe (S1) is manufactured.

  Thus, the sub-frame (S1) and the method of manufacturing the same have the following advantages.

  That is, since the frame unit (10) includes the first intermediate member (12) and the two end members (15) and (15), the first intermediate member ( By appropriately using a suitable length as 12), the pitch between both bracket portions (17) and (17) can be easily set to a desired size. Therefore, parts can be shared for the end members (15) and (15). Similarly, by appropriately selecting an end member (15) having an appropriate type of joint (16) as the end member (15), it is possible to easily cope with various types of automobiles. Therefore, parts can be shared for the intermediate member (12).

  In addition, in the manufacturing process of the frame unit (10), the joining means for joining the end member (15) to the end of the first intermediate member (12) is not a fusion welding but a solid phase utilizing frictional heat. Since the friction stir welding is used as the joining, deformation due to the joining hardly occurs. Therefore, after joining, the frame unit (10) has high dimensional accuracy with respect to the pitch (interval) between the two bracket portions (17) and (17). Therefore, when manufacturing the sub-frame (S1), it is not necessary to perform a straightening process for improving the dimensional accuracy of the pitch between the two bracket portions (17) (17) of the frame unit (10), or a simple straightening process can be performed. Only the processing needs to be performed. Therefore, the subframe (S1) can be manufactured efficiently, and the manufacturing cost of the subframe (S1) can be reduced.

  Furthermore, since the connecting frame unit (30) is composed of the second intermediate member (32) and the two connecting members (35) (35), the second intermediate member ( By appropriately using a suitable length as 32), the pitch between both connecting bosses (37) and (37) can be easily set to a desired size. Therefore, parts can be shared for the connecting members (35) and (35). Similarly, by appropriately selecting an appropriate type of connecting member (35) according to the type of vehicle, it is possible to easily cope with various types of vehicles. Therefore, parts can be shared for the second intermediate member (32).

Moreover, in the manufacturing process of the connection frame unit (30), the joining means for joining the connection member (35) to the end of the second intermediate member (32) is not fusion welding but friction stir welding. Deformation due to joining hardly occurs. Therefore, after joining, the connection frame unit (30) has high dimensional accuracy with respect to the pitch (interval) between the connection boss portions (37) and (37). Therefore, when manufacturing the sub-frame (S1), there is no need to perform a straightening process to improve the dimensional accuracy of the pitch between both connecting bosses (37) and (37) of the connecting frame unit (30), or it is easy. It is only necessary to perform a straightening process. Therefore, the subframe (S1) can be manufactured more efficiently, and the manufacturing cost of the subframe (S1) can be further reduced.

  Further, in the frame unit (10), both the first intermediate member (12) and the end member (15) are made of aluminum or an aluminum alloy, and the first intermediate member (12) is made of a tubular material. (S1) can be reduced in weight. Moreover, in the connecting frame unit (30), both the second intermediate member (32) and the connecting member (35) are made of aluminum or an aluminum alloy, and the second intermediate member (32) is made of a tubular material. (S1) can be significantly reduced in weight. Therefore, by mounting the subframe (S1) on the vehicle, it is possible to reduce the manufacturing cost of the subframe (S1) of the vehicle and also to improve the fuel efficiency of the vehicle.

  In the subframe (S1) of the first embodiment, the side frame (11) corresponds to the frame unit (10), and the cross member (31) corresponds to the connecting frame unit (30). Conversely, in the sub-frame of the invention, the cross member (31) may correspond to the frame unit (10), and the side frame (11) may correspond to the connecting frame unit (30).

  Further, in the connecting frame unit (30) of the sub-frame (S1) of the first embodiment, the lengthwise middle portion of the first intermediate member (12) and the lengthwise middle portion of the second intermediate member (32) are provided. May be subjected to plastic working such as bulging or hydroforming, in addition to the bending and crushing described above.

  When the first intermediate member (12) or the second intermediate member (32) is subjected to bending, the intermediate member has excellent extensibility such as JIS A6000-based aluminum alloy. It is desirable to be manufactured from a material (for example, JIS A6061-T4 material). By doing so, the intermediate member can be favorably bent.

  Actually, the constituent members of the sub-frame (S1) shown in FIG. 1 were welded and integrated with each other by fusion welding according to a conventional method to produce the sub-frame (S1). As a result, in the obtained sub-frame (S1), the pitch between the two bracket portions (17) and (17) was shifted from the target pitch by ± (2 to 3) mm. Further, the position of the bracket part (17) was shifted ± (2 to 3) mm vertically with respect to a target plane (horizontal plane) passing through the four bracket parts (17), (17), (17), and (17). .

  On the other hand, the constituent members of the sub-frame (S1) shown in FIG. 1 are joined and integrated with each other by solid-phase joining utilizing frictional heat according to the method of the first embodiment, and the sub-frame (S1) In the case of manufacturing the sub-frame (S1), the pitch between the two brackets (17) and (17) in the obtained sub-frame (S1) is preferably ± (0.5 to 1) mm from the target pitch. The position of the bracket part (17) is shifted by ± (0.5 to 1) mm with respect to a target plane (horizontal plane) passing through the four bracket parts (17), (17), (17), and (17). It is expected that it can be suppressed.

  Therefore, according to the present invention, it is presumed that a subframe (S1) having higher dimensional accuracy than a conventional subframe can be obtained.

  FIG. 5 is a perspective view showing a first modification of the end member (15) and the connecting member (35) in the sub-frame (S1) of the first embodiment.

  The end member (15) of the frame unit (10) is made of a machined product of an extruded material of aluminum or an aluminum alloy, and as a joint (16), a connecting bolt (not shown) for connecting to a vehicle body. ) Has a connection bolt insertion hole (22) through which the connection bolt is inserted.

  The connecting member (35) of the connecting frame unit (30) is made of a cut product of an extruded material of aluminum or an aluminum alloy, and has a connecting convex portion (42) having a square cross section.

  The connecting projection (42) of the connecting member (35) is fitted in the connecting recess (23) provided in the end member (15). Further, in this fitted state, the two bolts (55) and (55) are inserted into the bolt insertion holes (24) provided in the end member (15) and the connection projection (42) in a communicating state. Then, by being screwed into the nuts (56) (56), the end member (15) and the connecting member (35) are fastened by bolts (55) (55).

  Thus, the frame unit (10) is connected to the connecting member (35) of the connecting frame unit (30) by bolting (that is, mechanical connecting means).

  In the first modification, in the connecting step of the frame unit (10), the connecting means for connecting the frame unit (10) to the connecting member (35) of the connecting frame unit (30) is not a fusion welding but a bolt. Because of the tightening, no deformation occurs due to welding. Therefore, after the connection, the sub-frame has high dimensional accuracy with respect to the interval between the pair of frame units (10). Therefore, at the time of manufacturing the sub-frame, it is not necessary to perform a straightening process for improving the dimensional accuracy of the interval between the two frame units (10), or only a simple straightening process may be performed. Therefore, the subframe can be manufactured more efficiently, and the manufacturing cost of the subframe can be further reduced.

  FIG. 6 is a perspective view showing a second modification of the end member (15) and the connecting member (35) in the sub-frame (S1) of the first embodiment.

  As shown in FIG. 5, the end member (15) of the frame unit (10) has a joint bolt (not shown) for coupling with a vehicle body as a joint (16). It has a hole (22).

  The connecting member (35) of the connecting frame unit (30) has a connecting projection (42) having a square cross section.

  The connecting projection (42) of the connecting member (35) is fitted in the connecting recess (23) provided in the end member (15). Further, in this fitted state, the connecting member (35) and the end member (15) are joined by fusion welding (MIG, TIG, laser beam welding, etc.) or solid-phase welding using frictional heat (friction stir welding, friction stir welding, (Joining part J2) by welding or the like and integrated with each other.

  Thus, the frame unit (10) is connected to the connecting member (35) of the connecting frame unit (30) by fusion welding or solid-phase joining using frictional heat.

  FIGS. 7A and 7B are views for explaining a third modification of the end member (15) and the connecting member (35) in the sub-frame (S1) of the first embodiment.

  The end member (15) of the frame unit (10) has a first connecting plate (25) as shown in FIG. 7 (b). The first connection plate (25) is provided with a connection bolt insertion hole (22) through which a connection bolt (not shown) for connecting to the vehicle body is inserted, as a joint (16).

  The connecting member (35) of the connecting frame unit (30) has a second connecting plate (43). The second connection plate (43) is provided with a connection bolt insertion hole (44) through which the connection bolt is inserted.

  Then, the first connecting plate of the end member (15) is aligned with the connecting bolt insertion hole (22) of the end member (15) and the connecting bolt insertion hole (44) of the connecting member (35). The part (25) and the second connecting plate part (43) of the connecting member (35) are overlapped. Further, in this overlapped state, a plurality of (six in the figure) bolts (57) are inserted into bolt insertion holes provided in the first connecting plate portion (25) and the second connecting plate portion (43), respectively. (53) The end member (15) and the connecting member (35) are fastened by bolts (57) by being inserted into the communication state with (54) and screwed to the nut (58).

  Thus, the frame unit (10) is connected to the connecting member (35) of the connecting frame unit (30) by bolting (that is, mechanical connecting means).

  In the third modification, in the connecting step of the frame unit (10), the connecting means for connecting the frame unit (10) to the connecting member (35) of the connecting frame unit (30) is not a fusion welding but a bolt. Because of the tightening, the sub-frame has high dimensional accuracy with respect to the interval between the pair of frame units (10) after the connection, as in the first modification. Therefore, the subframe can be manufactured more efficiently, and the manufacturing cost of the subframe can be further reduced.

  8 and 9 are diagrams for explaining a subframe according to the second embodiment of the present invention.

  In FIG. 8, (S2) is a subframe according to the second embodiment. This subframe (S2) is used as a rear subframe or the like in an automobile (for example, an FF vehicle).

  As shown in FIG. 8, the sub-frame (S2) has a pair of left and right side members (11) and a pair of front and rear cross members (31) (31), as in the sub-frame (S1) of the first embodiment. ), And a central cross member (31) arranged between the pair of front and rear cross members (31) and (31).

  In the sub-frame (S2) of the second embodiment, the pair of side members (11) (11) correspond to the pair of frame units (10) (10). Further, of the three cross members (31), (31), (31), a pair of front and rear cross members (31), (31) respectively correspond to the connection frame unit (30). On the other hand, the center cross member (31) corresponds to the connecting frame (30F).

  In each frame unit (10) (that is, in each side member (11)), of the two end members (15) (15), the upper end member (15) in FIG. A connection bolt insertion hole (22) through which a connection bolt (not shown) for connecting to a vehicle body is inserted. The end member (15) has a connecting portion (18) and a first fitting projection (19), like the end member (15) of the subframe (S1) of the first embodiment. I have. Further, an arm connecting bracket (29) is integrally formed with the end member (15). The end member (15) is provided with a plurality of hollow holes (28) for weight reduction.

  On the other hand, in the figure, the lower end member (15) has, as a joint (16), a connection bolt insertion hole (22) through which a connection bolt (not shown) for connecting to the vehicle body is inserted. are doing. The end member (15) has a connecting portion (18) and a first fitting projection (19), like the end member (15) of the subframe (S1) of the first embodiment. are doing.

  Further, the first intermediate member (12) has the same configuration as the first intermediate member (12) of the sub-frame (S1) of the first embodiment.

  The first fitting projections (19) of the end member (15) are fitted into the first recesses (13a) on both end surfaces of the first intermediate member (12), respectively. (20) By simultaneously performing the friction stir welding on (20), the end members (15) are joined to both end portions of the first intermediate member (12), respectively (joining portion J1 thereof). Thus, each frame unit (10) is manufactured.

  The pair of front and rear connecting frame units (30) and (30) constituting the pair of front and rear cross members (31) and (31) are the connecting frame units (30) and (30) of the sub-frame (S1) of the first embodiment. ). On the other hand, the central connecting frame (30F) constituting the central cross member (31) is configured as follows.

  That is, the central connection frame (30F) is formed of a rod-shaped tube having a predetermined length, and has a hollow portion (33) provided in a lengthwise manner and penetrating therethrough. The center connection frame (30F) is formed in a circular cross section.

  In the second embodiment, the central connection frame (30F) is made of, for example, an extruded tube or an electric resistance welded tube of aluminum or an aluminum alloy.

  In the sub-frame (S2), as shown in FIGS. 8 and 9, the first intermediate member (12) of the frame unit (10) is fusion-welded (MIG, TIG) to both ends of the central connecting frame (30F). , Laser beam welding, etc.) or solid-phase welding using frictional heat (friction stir welding, friction welding, etc.), and are directly joined (the joint J2 thereof). In this way, the frame units (10) are connected to both ends of the center connection frame (30F).

  The other configuration and the other manufacturing method of the sub-frame (S2) are the same as the configuration and the manufacturing method of the sub-frame (S1) of the first embodiment, and a duplicate description will be omitted.

  FIGS. 10 to 12 are diagrams for explaining a subframe according to the third embodiment of the present invention.

  In FIG. 10, (S3) is a subframe according to the third embodiment. This subframe (S3) is used as a rear subframe or the like in an automobile (for example, an FR car).

  The frame unit (10) constituting the side member (11) of the sub-frame (S3) is composed of the first intermediate member (12) and the two end members (15 ) (15).

  Both ends of the first intermediate member (12) are formed straight, and only the intermediate portion in the longitudinal direction of the intermediate member (12) is bent in a substantially rectangular shape by bending such as press bending. .

  The end member (15) is not provided with the connecting recess (21) (see FIG. 2B).

  On the other hand, the connecting frame (30F) constituting the cross member (31) of the sub-frame (S3) is formed of a rod-shaped tube having a predetermined length, and is provided with a hollow portion ( 33). This connection frame (30F) is formed in a circular cross section.

  Next, a process of manufacturing the frame unit (10) in the method of manufacturing the subframe (S3) will be described.

[Production process of frame unit (10)]
First, as shown in FIG. 11, a first intermediate member (12) made of a rod-like tubular material formed straight over the entire length is prepared. The first intermediate member (12) is formed in a perfect circular cross section and has a predetermined length.

  In addition, two end members (15) having the bush mounting bracket (17), the connecting portion (18), and the first fitting protrusion (19) are prepared.

  Next, as shown in the figure, the first fitting projections (19) of the end member (15) are fitted to the first recesses (13a) on both end surfaces of the first intermediate member (12), respectively, in a tight or slight manner. Fit tightly. In this fitting state, the outer peripheral surface of the end of the first intermediate member (12) and the outer peripheral surface of the connecting portion (18) of the end member (15) are flush with each other.

  Next, friction stir welding is simultaneously performed on the two fitting portions (20) and (20). As a result, the end members (15) are respectively joined to both ends of the first intermediate member (12) (the joint J1).

  Next, as shown in FIG. 12, only the middle part in the length direction of the first intermediate member (12) is bent by bending such as press bending. On the other hand, both ends of the first intermediate member (12) maintain a straight shape without performing the bending process. By doing so, it is possible to prevent the joint (J1) from cracking, which may occur with the bending of the first intermediate member (12).

  Through the above manufacturing steps, the frame unit (10) is manufactured.

  In the sub-frame (S3), as shown in FIG. 10, the first intermediate member (12) of the corresponding frame unit (10) is melt-welded (MIG, TIG, laser) to the end of the connection frame (30F). Beam welding or the like) or solid-phase welding (friction stir welding, friction welding, etc.) utilizing frictional heat is directly joined (the joint J2 thereof). In this way, the frame units (10) are connected to both ends of the connection frame (30F).

  The other configuration and the other manufacturing method of the sub-frame (S3) are the same as the configuration and the manufacturing method of the sub-frame (S1) of the first embodiment, and a duplicate description will be omitted.

  FIG. 13 is a diagram for explaining a subframe according to the fourth embodiment of the present invention.

  In the figure, (S4) is a subframe according to the fourth embodiment. The subframe (S4) is used as a front subframe (for example, an engine cradle) in an automobile (for example, an FR car).

  In the frame unit (10) constituting the side member (11) of the sub-frame (S4), of the two end members (15) and (15), the upper end member (15) in FIG. Has a connection bolt insertion hole (22) through which a connection bolt (not shown) for connecting to a vehicle body is inserted as a joint (16). The end member (15) has a connecting portion (18) and a first fitting projection (19), like the end member (15) of the subframe (S1) of the first embodiment. I have. The end member (15) is provided with a plurality of hollow holes (28) for weight reduction.

  On the other hand, in the figure, the lower end member (15) has, as a joint (16), a connection bolt insertion hole (22) through which a connection bolt (not shown) for connecting to the vehicle body is inserted. are doing. The end member (15) has a connecting portion (18) and a first fitting projection (19), like the end member (15) of the subframe (S1) of the first embodiment. are doing.

  The first fitting projections (19) of the end member (15) are fitted into the first recesses (13a) on both end surfaces of the first intermediate member (12), respectively. (20) By simultaneously performing the friction stir welding on (20), the end members (15) are joined to both end portions of the first intermediate member (12), respectively (joining portion J1 thereof). Thus, each frame unit (10) is manufactured.

  The first intermediate member (12) has both ends formed straight, and only the intermediate portion in the length direction is bent.

  Further, of the pair of front and rear connection frames (30F) and (30F) (that is, the pair of front and rear cross members (31) and (31)), the upper connection frame (30F) in the figure includes a connection frame unit (30). . The connection frame unit (30) has the same configuration as the connection frame unit (30) of the subframe (S1) of the first embodiment.

  On the other hand, in the figure, the lower connection frame (30F) is made of a rod-shaped tube having a predetermined length. This connection frame (30F) is formed in a square cross section. In the present invention, the connecting frame (30F) may be formed in a cross-shaped Japanese character.

  In the sub-frame (S4), the first intermediate member (12) of the corresponding frame unit (10) is fusion-welded (MIG, TIG, laser beam) to the end of the lower connection frame (30F) in the figure. (Welding, etc.) or solid-phase welding utilizing frictional heat (friction stir welding, friction welding, etc.) and are directly joined (the joint J2 thereof). In this way, the frame units (10) are connected to both ends of the connection frame (30F).

  The other configuration and the other manufacturing method of the subframe (S4) are the same as the configuration and the manufacturing method of the subframe (S1) of the first embodiment, and a duplicate description will be omitted.

  Thus, in the present invention, the connection structure between the frame unit (10) and the connection frame unit (30) is not limited to the one shown in the above embodiment, and various settings can be changed. A modified example is shown in FIGS. 14 (a) and (b).

  In the figure, the second intermediate member (32) of the connection frame unit (30) is made of a rod-shaped tube having a predetermined length, and has a hollow portion (33) provided in a penetrating shape in the length direction. I have. Therefore, second concave portions (33a) are provided on both end surfaces of the second intermediate member (32). The second intermediate member (32) has a circular cross section.

  The connecting member (35) of the connecting frame unit (30) has a joining bracket (45) to be joined to the first intermediate member (12) of the frame unit (10). The joining bracket (45) has a bearing hole (46) for connecting an arm (not shown). Further, the connecting member (35) has a connecting portion (38) and a second fitting convex portion (39).

  The second fitting projections (39) of the connecting member (35) are fitted into the second recesses (33a) on both end surfaces of the second intermediate member (32), respectively. By simultaneously applying the friction stir welding to (40) and (40), the connecting members (35) are respectively joined to both ends of the second intermediate member (32) (the joint J1 thereof). Thus, the connection frame unit (30) is manufactured.

  Then, the first intermediate member (12) of the corresponding frame unit (10) applies fusion welding (MIG, TIG, laser beam welding, etc.) or frictional heat to the joining bracket (45) of the connection frame unit (30). Joining (the joint J2) is performed by using solid phase welding (friction stir welding, friction welding, etc.). In this way, the frame units (10) are connected to both ends of the connection frame unit (30), respectively.

  FIGS. 15 and 16 are diagrams illustrating a subframe according to the fifth embodiment of the present invention.

  In FIG. 15A, (S5) is a subframe according to the fifth embodiment. This subframe (S5) is used as a rear subframe (also referred to as a "cross member") in an automobile. This sub-frame (S5) is arranged substantially horizontally when mounted on a vehicle.

  As shown in FIG. 15A, the sub-frame (S5) includes a pair of front and rear cross members (31) and (31) that extend in the left-right direction of the vehicle and are spaced apart and opposed to each other. , A plurality of (three in the figure) connecting plates (34). The connection plate (34) is for connecting the pair of cross members (31), (31) to each other, and is disposed between the two cross members (31), (31). The pair of cross members (31), (31) are connected to each other via the connection plate (34).

  In the sub-frame (S5) of the fifth embodiment, a pair of front and rear cross members (31) and (31) correspond to a pair of frame units (10) and (10), and three connecting plates (34). ), (34) and (34) respectively correspond to the connection frame (30F).

  Each frame unit (10) (that is, the cross member (31)) includes a first intermediate member (12) and two end members (15) (15) formed in the same shape and the same size. I have.

  Like the end member (15) of the subframe (S1) of the first embodiment, the end member (15) includes a bush mounting bracket (17) as a joint (16) and a connecting portion (18). ) And a first fitting projection (19).

  The first intermediate member (12), like the first intermediate member (12) of the sub-frame (S1) of the first embodiment, is made of a rod-shaped tube having a predetermined length, and is provided penetrating in the length direction. It has a hollow portion (13). Therefore, the first concave portions (12a) are provided on both end surfaces of the second intermediate member (12). The outer peripheral surfaces of both ends of the first intermediate empty member (12) are each formed in a circular cross section.

  Then, as shown in FIG. 15A, the first fitting projections (19) of the end member (15) are fitted into the first recesses (13a) on both end faces of the first intermediate member (12). At the same time, the friction stir welding is simultaneously performed on the two fitting portions (20) and (20), so that the end members (15) are joined to both ends of the first intermediate member (12), respectively. The joint J1) has been made.

  Further, as shown in FIG. 15B, both end portions of the first intermediate member (12) are formed straight, and only the middle portion in the longitudinal direction of the first intermediate member (12) is press-bent. And the like, and are bent upward by protruding in an arc shape.

  Further, as shown in FIG. 15B, a bracket (51) for connecting an arm and a bracket (52) for mounting a differential device are joined to the first intermediate member (12).

  The manufacturing process of the frame unit (10) in the subframe (S5) of the fifth embodiment is the same as the manufacturing process of the frame unit (10) in the subframe (S3) of the third embodiment shown in FIGS. It is the same, and duplicate description is omitted.

  On the other hand, each connection frame (30F) (that is, the connection plate (34)) is made of wrought aluminum or an aluminum alloy.

  Next, a connecting process of the frame unit (10) in the method of manufacturing the sub-frame (S5) will be described.

[Frame unit connection process]
First, as shown in FIG. 16 (a), a pair of frame units (10), (10) are spaced apart from each other and arranged to face each other. Then, the connecting concave portion (23) and the connecting convex portion (42) provided in the two end members (15) (15) corresponding to each other are fitted. Further, in this fitted state, the end members (15) and (15) are welded to each other by fusion welding (MIG, TIG, laser beam welding, etc.) or solid-phase welding using frictional heat (friction stir welding, friction welding, etc.). Joining (joining portion J2) to integrate with each other.

  Next, the connecting frame (30F) is arranged between the first intermediate members (12) (12) of both frame units (10) (10). In this state, the first intermediate member (12) of the frame unit (10) is melt-welded (MIG, TIG, laser beam welding, or the like) to both ends of the connection frame (30F) or solid-phase joining using frictional heat (friction) Each is joined (the joint J2) by stirring welding, friction welding, or the like. In this way, the frame units (10) are connected to both ends of the connection frame (30F).

  Through the above connecting step, the pair of frame units (10) is connected to each other via the connecting frame (34).

  Then, as shown in FIG. 15B, the arm connection bracket (51) and the differential device mounting bracket (52) are joined. This joining may be performed before the connecting step of the frame unit (10).

  Through the above steps, the subframe (S5) is manufactured.

  FIGS. 17A to 17C are diagrams illustrating a subframe according to the sixth embodiment of the present invention.

  In FIG. 17A, (S6) is a subframe according to the sixth embodiment. The sub-frame (S6) includes a pair of front and rear cross members (31) (31) that extend in the left-right direction of the vehicle and that are spaced apart from each other and are opposed to each other, as shown in FIG. And a pair of front and rear connection frames (30F) (30F) that are extended in the front-rear direction and are spaced apart and opposed to each other. Each connecting frame (30F) is for connecting a pair of cross members (31), (31), and is arranged between both cross members (31), (31). The pair of cross members (31), (31) are connected to each other via the connection frame (30F).

  In the subframe (S6) of the sixth embodiment, a pair of front and rear cross members (31) and (31) are paired with a pair of frame units (10) and (10), similarly to the subframe (S5) of the fifth embodiment. It corresponds to.

  Each frame unit (10) (that is, the cross member (31)) has the same shape and the same size as the first intermediate member (12), similarly to the frame unit (10) of the subframe (S5) of the fifth embodiment. And two end members (15) and (15) formed at the same time.

  Like the end member (15) of the subframe (S1) of the first embodiment, the end member (15) includes a bush mounting bracket (17) as a joint (16) and a connecting portion (18). ) And a first fitting projection (19).

  The first intermediate member (12), like the first intermediate member (12) of the sub-frame (S1) of the first embodiment, is made of a rod-shaped tube having a predetermined length, and is provided penetrating in the length direction. It has a hollow portion (13). For this reason, first concave portions (13a) are provided on both end surfaces of the first intermediate member (12). The outer peripheral surfaces of both ends of the first intermediate member (12) are each formed in a circular cross section.

  Then, as shown in FIG. 17A, the first fitting projections (19) of the end member (15) are fitted into the first recesses (13a) on both end faces of the first intermediate member (12). At the same time, the friction stir welding is simultaneously performed on the two fitting portions (20) and (20), so that the end members (15) are joined to both ends of the first intermediate member (12), respectively. The joint J1) has been made.

  Further, of the pair of frame units (10), both ends of the first intermediate member (12) are formed straight in the lower frame unit (10) in FIG. Only the middle part in the length direction of the intermediate member (12) is bent in a substantially rectangular shape in a substantially horizontal plane by bending such as press bending.

  On the other hand, in the upper frame unit (10) in the figure, the first intermediate member (12) is formed straight over the entire length.

  Each connecting frame (30F) is made of a hollow cast product having a substantially U-shaped cross section of aluminum or an aluminum alloy, as shown in FIG. A plurality of reinforcing ribs (47) are provided in the hollow part (33). Further, arm connecting brackets (50) are formed integrally on the upper and lower surfaces of the connecting frame (30F) one by one.

  In the sub-frame (S6), the connection frame (30F) is disposed between the first intermediate members (12) and (12) of both frame units (10) and (10), and in this state, the connection frame (30F) The first intermediate member (12) of the frame unit (10) is melt-welded (MIG, TIG, laser beam welding, etc.) or solid-phase welding utilizing frictional heat (friction stir welding, friction welding, etc.) at each end of the frame unit (10). Joined (the joint J2).

  Although some preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various settings can be changed.

  For example, in the frame unit (10) of the sub-frame of the above embodiment, the joining means for joining the end member (15) to the end of the first intermediate member (12) may be friction welding. Similarly, in the connection frame unit (30) of the sub-frame of the above embodiment, the joining means for joining the connection member (35) to the end of the second intermediate member (32) may be friction welding. .

  Further, the first intermediate member (12) and the end member (15) of the frame unit (10) and the second intermediate member (32) and the coupling member (35) of the coupling frame unit (30) are made of magnesium alloy. There may be.

  Further, the first intermediate member (12) and the second intermediate member (32) are made of a rod-shaped hollow member having one or a plurality of reinforcing ribs (not shown) provided in the hollow part (30); As a specific example, it may be formed in a cross-shaped letter shape, a cross-shaped letter shape, a cross-shaped cross-sectional shape, or the like.

  INDUSTRIAL APPLICABILITY The present invention is applicable to an automobile subframe, an automobile, and a method of manufacturing an automobile subframe.

FIG. 2 is a plan view of a subframe according to the first embodiment of the present invention. (A) is a side view of the frame unit (side member) of the subframe, and (b) is a partially cutaway plan view of the frame unit (side member) of the subframe. FIG. 4 is a partially cutaway plan view showing a connection frame unit (cross member) of the subframe in a state before bending. 4A is a perspective view showing a connected frame unit (cross member) of the subframe in a state after being bent, FIG. 4B is a cross-sectional view taken along line AA in FIG. 4A, and FIG. It is BB sectional drawing in a). It is a perspective view showing the 1st modification of an end member and a connecting member in the same subframe. It is a perspective view which shows the 2nd modification of an end member and a connection member in the same sub-frame. (A) is a top view which shows the 3rd modification of the end member in the same subframe, and a connection member, (b) is CC sectional view taken on the line in (a) of FIG. It is a top view of a sub-frame concerning a 2nd embodiment of the present invention. It is DD sectional drawing in FIG. It is a top view of a subframe concerning a 3rd embodiment of the present invention. FIG. 4 is a partially cutaway plan view showing a frame unit (side member) of the sub-frame in a state before bending. It is a top view which shows the frame unit (side member) of the same sub-frame in the state after bending. It is a top view of the sub-frame concerning a 4th embodiment of the present invention. (A) is a cross-sectional view corresponding to a cross-sectional view taken along the line DD in FIG. 8, showing a modified example of the connection structure between the frame unit and the connection frame unit in the subframe of the above embodiment, and (b) is It is a partially cutaway plan view. (A) is a plan view of a subframe according to a fifth embodiment of the present invention, and (b) is a front view of the subframe. (A) is a top view which shows the state in the middle of manufacture of the same sub-frame, (b) is a front view of the same sub-frame. (A) is a plan view of a subframe according to a sixth embodiment of the present invention, (b) is a cross-sectional view taken along line EE in FIG. 17 (a), and (c) is a cross-sectional view taken along line FF in FIG. FIG.

Explanation of reference numerals

S1, S2, S3, S4, S5, S6 ... subframe
10… Frame unit
11… Side member
12 First intermediate member (intermediate member)
13 ... hollow part
13a: First recess (recess)
15 ... End member
16 Joint
17… Bracket
19: First fitting projection (fitting projection)
20… Mating part
22 ... Connecting bolt insertion hole
30F… Connection frame
30… Connection frame unit
31… Cross member
32 ... Second intermediate member
33 ... hollow
33a ... Second recess
34 ... Connecting plate
35 ... Connecting member
37 ... Connection boss
39: second fitting projection
40… Mating part
42 ... Connecting projection
60 ... welding tool for friction stir welding
J1: Joints by friction stir welding
J2 ... Junction

Claims (29)

It comprises a pair of frame units spaced apart and facing each other,
In an automobile sub-frame, the two frame units are connected to each other via a connection frame disposed therebetween.
The frame unit is configured such that end members having joints connected to other members are joined to both ends of an intermediate member made of a rod-shaped material by solid-state joining using frictional heat, respectively. A sub-frame of a motor vehicle characterized by: In the frame unit,
Recesses are provided on both end faces of the intermediate member, respectively.
The fitting protrusions provided on the end member are fitted into the recesses on both end surfaces of the intermediate member, respectively,
The automobile sub-frame according to claim 1, wherein each of the fitting portions is subjected to friction stir welding as the solid-phase welding. In the frame unit,
The automobile sub-frame according to claim 1 or 2, wherein outer peripheral surfaces of both end portions of the intermediate member are each formed in a circular cross section. In the frame unit,
The automobile subframe according to any one of claims 1 to 3, wherein both ends of the intermediate member are formed straight, and a longitudinal intermediate portion of the intermediate member is bent.   The automobile subframe according to any one of claims 1 to 4, wherein the intermediate member is formed of a rod-shaped hollow material.   The vehicle subframe according to any one of claims 1 to 5, wherein at least one of the intermediate member and the end member is made of light metal. As the connection frame,
A connecting member connected to the frame unit is joined to both ends of a second intermediate member made of a rod-shaped material by a second solid-phase joining using frictional heat, so that the connecting frame unit configured is used. An automotive subframe according to any one of claims 1 to 6, wherein   The vehicle sub-frame according to claim 7, wherein the frame unit is connected to both connecting members of the connecting frame unit by mechanical connecting means. In the connection frame unit,
Second concave portions are provided on both end surfaces of the second intermediate member, respectively.
The second fitting protrusions provided on the connection member are fitted into the second recesses on both end surfaces of the second intermediate member, respectively,
9. The sub-frame of an automobile according to claim 7, wherein each of the fitting portions is subjected to friction stir welding as the second solid-phase welding. In the connection frame unit,
The sub-frame for an automobile according to any one of claims 7 to 9, wherein outer peripheral surfaces of both end portions of the second intermediate member are each formed in a circular cross section. In the connection frame unit,
The automobile subframe according to any one of claims 7 to 10, wherein both end portions of the second intermediate member are formed straight, and a longitudinal intermediate portion of the second intermediate member is bent.   The vehicle sub-frame according to any one of claims 7 to 11, wherein the second intermediate member is formed of a rod-shaped hollow material.   The vehicle subframe according to any one of claims 7 to 12, wherein at least one of the second intermediate member and the connecting member is made of light metal.   An automobile equipped with the subframe according to any one of claims 1 to 13. It comprises a pair of frame units spaced apart and facing each other,
In a method for manufacturing a subframe of an automobile, wherein the two frame units are connected to each other via a connection frame disposed therebetween.
A frame unit is manufactured by joining end members having joints connected to other members to both ends of an intermediate member made of a rod-shaped material by solid-phase joining using frictional heat, respectively, to produce a frame unit. Manufacturing process,
Connecting the frame units to both ends of a connection frame, respectively, connecting the frame units,
A method for manufacturing a subframe of an automobile, comprising: In the manufacturing process of the frame unit,
Recesses are provided on both end faces of the intermediate member, respectively.
After fitting the fitting protrusion provided on the end member to one of the recesses on both end surfaces of the intermediate member,
16. The method for manufacturing a subframe for an automobile according to claim 15, wherein the fitting portion is subjected to friction stir welding as the solid-phase welding. In the manufacturing process of the frame unit,
Recesses are provided on both end faces of the intermediate member, respectively.
After fitting fitting protrusions provided on the end member to recesses on both end surfaces of the intermediate member formed straight over the entire length, respectively,
16. The method for manufacturing a subframe of an automobile according to claim 15, wherein friction stir welding is simultaneously performed on the two fitting portions as the solid-phase welding.   The method for manufacturing a subframe of an automobile according to any one of claims 15 to 17, wherein outer peripheral surfaces of both ends of the intermediate member are each formed in a circular cross section. In the manufacturing process of the frame unit,
At both ends of the intermediate member formed straight over the entire length, the end members are respectively joined by the solid-phase joining,
19. The method of manufacturing a subframe for an automobile according to claim 15, wherein only the intermediate portion in the length direction of the intermediate member is bent.   20. The method according to claim 15, wherein the intermediate member is made of a rod-shaped hollow material.   The method for manufacturing a subframe of an automobile according to any one of claims 15 to 20, wherein at least one of the intermediate member and the end member is made of light metal.   Further, a connecting member connected to the frame unit is joined to both ends of a second intermediate member made of a rod-shaped material by a second solid-phase joining using frictional heat, so that the connecting frame unit serves as the connecting frame. 22. The method for manufacturing a subframe of an automobile according to any one of claims 15 to 21, further comprising the step of manufacturing a connection frame unit. In the connecting step of the frame unit,
The method according to claim 22, wherein the frame unit is connected to both connecting members of the connecting frame unit by mechanical connecting means. In the manufacturing process of the connecting frame unit,
Second concave portions are provided on both end surfaces of the second intermediate member, respectively.
After fitting the fitting protrusion provided on the connecting member to one of the second recesses on both end surfaces of the second intermediate member,
24. The method according to claim 22, wherein friction stir welding is performed on the fitting portion as the second solid-phase welding. In the manufacturing process of the connecting frame unit,
Second concave portions are provided on both end surfaces of the second intermediate member, respectively.
After fitting fitting protrusions provided on the connecting member to second recesses on both end surfaces of the second intermediate member formed straight over the entire length, respectively,
24. The method for manufacturing a subframe of an automobile according to claim 22, wherein friction stir welding is simultaneously performed on the two fitting portions as the second solid-phase welding.   The method for manufacturing a subframe of an automobile according to any one of claims 21 to 25, wherein outer peripheral surfaces of both end portions of the second intermediate member are each formed in a circular cross section. In the manufacturing process of the connecting frame unit,
The connecting member is joined to both ends of the second intermediate member formed straight over the entire length by the second solid-state joining, respectively,
27. The method according to claim 22, wherein only the middle portion in the length direction of the second intermediate member is bent.   The method according to any one of claims 22 to 27, wherein the second intermediate member is formed of a rod-shaped hollow material. The method for manufacturing a subframe of an automobile according to any one of claims 22 to 28, wherein at least one of the second intermediate member and the connecting member is made of light metal.

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