WO2019198727A1

WO2019198727A1 - Component having top plate and side wall

Info

Publication number: WO2019198727A1
Application number: PCT/JP2019/015515
Authority: WO
Inventors: 伊藤　泰弘
Original assignee: 日本製鉄株式会社
Priority date: 2018-04-09
Filing date: 2019-04-09
Publication date: 2019-10-17
Also published as: JPWO2019198727A1; CN111918781B; JP6822607B2; CN111918781A

Abstract

In a component having a side wall comprising a curved portion, vibration of the component causes elastic deformation of the side wall so as to open outwardly or incline inwardly. During such deformation, stress is generated in the base of the side wall, and repeated occurrence of stress causes fatigue cracks at the base. This component has a top plate and a side wall formed by bending the periphery of the top plate and has an open cross section in a direction perpendicular to the top plate. The side wall includes a curved portion that has a shape protruding or recessed toward the inner side of the component as viewed from a direction perpendicular to the top plate, and that is curved with a curvature radius of 300 mm or less. A reinforcing member which is joined to the side wall is provided at least on a portion of the curved portion.

Description

Parts with top plate and side wall

(Cross-reference of related applications)
This application claims priority based on Japanese Patent Application No. 2018-074634 for which it applied to Japan on April 9, 2018, and uses the content here.

The present invention relates to a component having a top plate portion and a side wall portion.

Auto bodies are required to be lighter for the purpose of reducing CO ₂ emissions and improving fuel efficiency. In connection with this, each part which comprises a vehicle body is thinned, For example, thickness reduction is also progressing also about suspension parts, such as a front lower arm and a rear lower arm. Patent Document 1 and Patent Document 2 disclose a front lower arm as a suspension part.

Japanese Patent Laying-Open No. 2015-209044 Japanese Patent Laying-Open No. 2015-231780

FIG. 1 is a perspective view showing a front lower arm 50 of an automobile. A front lower arm 50 in FIG. 1 has a top plate portion 2 and side wall portions 3 formed by bending the top plate portion 2 around the top plate portion 2. The top plate 2 is formed so as to extend in three directions from the center in plan view. The ends on the front end side of the portions extending in three directions are respectively the first vehicle body attachment side end portion 4 which is an end portion attached to the vehicle body side and the second vehicle body attachment side end which is an end portion attached to the vehicle body side. Part 5 and a wheel attachment side end 6 which is an end attached to the wheel side. The portions that connect the end portions 4 to 6 include portions that are curved in plan view, and the side wall portion 3 is also formed in the curved portion.

The side wall portion of the curved portion is formed by elongation deformation or contraction deformation during the blank press forming process. That is, a part having a side wall portion in the curved portion has at least one of a portion formed by expansion deformation and a portion formed by contraction deformation. In the present specification, a portion of the side wall portion formed by elongation deformation and having a curved shape that is convex toward the center of the member (front lower arm 50) is referred to as a “convex curved portion” and is recessed toward the center of the member. A portion having a curved shape which is a shape is referred to as a “concave curved portion”.

The front lower arm 50 shown in FIG. 1, which is an example of a part having a side wall portion in the curved portion, has the side wall portion 3 outward as shown in FIG. 2, while accompanying expansion or contraction deformation of the side wall portion 3 due to vibration during vehicle travel. Elastically deforms so that it opens or falls inward. At this time, since stress is generated at the base of the side wall 3, fatigue cracks may occur inside the base plate of the side wall 3 due to repeated stress acting on the base of the side wall 3 due to vibration. . In particular, since an underbody part of an automobile is easily affected by vibration during traveling, a fatigue crack is more likely to occur at the base of the side wall portion 3 than other parts. Furthermore, the above-mentioned thinning performed from the viewpoint of weight reduction increases the stress generated by vibration, and fatigue cracks are likely to occur. Therefore, it is desired to suppress the occurrence of fatigue cracks while reducing the thickness for weight reduction.

The present invention has been made in view of the above circumstances, and an object thereof is to suppress the occurrence of fatigue cracks in a component having a top plate portion and a side wall portion.

In order to solve the above-described problem, according to the present invention, a top plate portion and a side wall portion formed by bending the top plate portion around the top plate portion are provided, and are perpendicular to the top plate portion. A part having an open cross section in a direction, wherein the side wall part has a concave part or a convex part in a part inner direction when viewed from a direction perpendicular to the top plate part, and a curved part curved with a curvature radius of 300 mm or less. A component is provided, wherein at least a part of the curved portion is provided with a reinforcing member joined to the side wall portion.

The reinforcing member may be provided at least at the front end of the side wall in the extending direction.

The reinforcing member may be provided in a curved portion that curves with a radius of curvature of 20 mm or more and 250 mm or less when viewed from a direction perpendicular to the top plate portion.

The reinforcing member may be provided in a curved portion that is curved when a radius of curvature viewed from a direction perpendicular to the top plate portion is not less than 4 times and not more than 375 times the plate thickness of the side wall portion.

The reinforcing member may be provided in the curved portion so as to include a portion having a minimum curvature radius when viewed from a direction perpendicular to the top plate portion.

In the circumferential direction of the bending portion, the length of the reinforcing member provided in the bending portion may be 80% or more of the length of the bending portion.

The plate thickness of the side wall portion may be 5.0 mm or less.

The reinforcing member may be a resin member made of resin.

The resin may be FRP.

The fiber orientation of the reinforcing fiber material included in the FRP may be within ± 30 ° with respect to the circumferential direction of the curved portion.

The FRP may be CFRP.

The FRP may be GFRP.

The reinforcing member may be a built-up part.

The part may be an automobile part.

The automobile part may be a suspension part.

According to the present invention, it is possible to suppress the occurrence of fatigue cracks in a component having a top plate portion and a side wall portion.

It is a perspective view which shows the conventional front lower arm. It is a figure which shows the behavior of the side wall front-end | tip part at the time of the vibration generation in the conventional front lower arm. It is a perspective view which shows the front lower arm which concerns on embodiment of this invention. It is the figure which looked at the front lower arm which concerns on embodiment of this invention from the extending | stretching direction of the side wall part. It is the enlarged view which looked at the part to which the CFRP (carbon fiber reinforced resin) member of the convex curve part joined based on embodiment of this invention was seen from the extending | stretching direction of the side wall part. In this figure, the force which acts on the convex curve part when a side wall part opens outside is shown. It is the enlarged view which looked at the part to which the CFRP member of the convex curve part joined based on embodiment of this invention was seen from the extending | stretching direction of the side wall part. In this figure, the force which acts on the convex curve part when a side wall part falls inward is shown. It is a perspective view which shows the front lower arm which concerns on another embodiment of this invention. It is a perspective view which shows the front lower arm which concerns on another embodiment of this invention. It is a perspective view which shows the front lower arm which concerns on another embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the CFRP member which concerns on another embodiment of this invention. It is a figure which shows the analysis model of stress simulation (A). It is a figure which shows the analysis model of stress simulation (B).

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a front lower arm of an automobile will be described as an example of a component having a side wall portion in a curved portion. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 3, the front lower arm 1 of the present embodiment has a top plate portion 2 and a side wall portion 3 formed by bending the top plate portion 2 around the top plate portion 2. The side wall portion 3 extends so that the side wall surface 3 a is perpendicular to the top surface of the top plate portion 2, and the longitudinal sectional shape of the front lower arm 1 is substantially U-shaped. That is, the front lower arm 1 has a side wall portion 3 formed by bending the top plate portion 2 around the top plate portion 2 and has an open cross section in a direction perpendicular to the top plate portion 2. The “side wall surface” in the present specification refers to a surface in the range from the tip position of the side wall part 3 to the bending start position of the connection part between the side wall part 3 and the top plate part 2 in a longitudinal sectional view. In the present specification, the direction in which the side wall 3 extends in the longitudinal sectional view of the component is referred to as “extending direction D of the side wall 3”. In the present embodiment, since the angle formed between the top surface of the top plate portion 2 and the side wall surface 3a is 90 °, the view when the front lower arm 1 is viewed from the extending direction D of the side wall portion 3 is shown in FIG. Thus, the front lower arm 1 is viewed from directly below. Further, in the present specification, the length direction of the arc of the side wall portion 3 viewed from the extending direction D of the side wall portion 3 is referred to as “circumferential direction C of the side wall portion 3”. The angle formed between the top surface of the top plate 2 and the side wall surface 3a is not limited to 90 °.

In addition, although it is assumed that the front lower arm 1 according to the present embodiment is made of steel, the material of the front lower arm 1 is not particularly limited as long as the material is metal. For example, the material of the front lower arm 1 may be an aluminum alloy or the like. The front lower arm 1 is mainly composed of a metal material, but other materials may be partially used.

As shown in FIG. 4, the front lower arm 1 is formed such that the top plate portion 2 extends from the center in three directions. The end portions on the front end side of the portions extending in three directions are respectively the first vehicle body attachment side end portion 4 which is an end portion attached to the vehicle body side, and the second vehicle body attachment which is an end portion similarly attached to the vehicle body side. A side end 5 and a wheel attachment side end 6 which is an end attached to the wheel side. The portion connecting the end portions 4 to 6 includes a curved portion, and the side wall portion 3 is also formed on the curved portion. In addition, the shape of the front lower arm 1 of this embodiment is an example, and the shape of the front lower arm 1 is suitably changed according to the suspension shape etc. of a motor vehicle. The plate thickness of the side wall portion 3 is designed to be, for example, 0.8 to 5.0 mm, more preferably 3.2 mm or less, further 2.9 mm or less, and 2.3 mm or less. If the thickness of the side wall 3 is less than 0.8 mm, the component strength is insufficient, and if it exceeds 5.0 mm, the weight of the component increases. Therefore, it is desirable to design the thickness of the side wall portion 3 as thin as possible within the above numerical range.

As described above, when the side wall portion is formed on the curved portion, the blank is deformed or contracted in the press molding process. Therefore, one or both of the convex curved portion and the concave curved portion are formed on the side wall portion of the curved portion. It is formed. Also in this embodiment, a convex curved portion 7 or a concave curved portion 8 is formed on the side wall portion 3 formed in the curved portion. The convex curved portion 7 is a convex portion in the component inner direction of the front lower arm 1 when viewed from the extending direction D of the side wall 3, and the concave curved portion 8 is the front viewed from the extending direction D of the side wall 3. The lower arm 1 is a concave portion in the component inner direction. In the case of the front lower arm 1 of the present embodiment, there are a plurality of convex curved portions 7 and concave curved portions 8 respectively. However, in FIG. 3 and FIG. 4, the convex curved portions 7 and the concave curved portions 8 are shown for convenience of explanation. Each one is shown. Here, the region in the circumferential direction C of the side wall portion 3 of the convex curved portion 7 and the concave curved portion 8 may be a portion that is curved in the circumferential direction C of the side wall portion 3. That is, even if the portion where the radius of curvature is 300 mm or less, for example, when viewed from the extending direction D of the side wall 3, is the region of the convex curved portion 7 and the concave curved portion 8 in the circumferential direction C of the side wall 3. good. Strictly speaking, the regions of the convex curved portion 7 and the concave curved portion 8 in the circumferential direction C of the side wall portion 3 may have a curvature radius of 20 mm or more and 250 mm or less. As described above, the thickness of the side wall portion 3 is, for example, 0.8 mm to 5.0 mm. Therefore, when the radius of curvature is 300 mm or less when viewed from the extending direction D of the side wall portion 3, the curvature radius is equal to the side wall portion. When the radius of curvature is 250 mm or less, it can be said that the radius of curvature is preferably 300 times or less of the thickness of the side wall 3.

The front lower arm 1 of the present embodiment has a CFRP member 9 made of CFRP (carbon fiber reinforced resin) as an example of a reinforcing member, in addition to a front lower arm main body having a top plate portion 2 and a side wall portion 3. Such a CFRP member 9 is lightweight and excellent in strength and specific rigidity. The CFRP member 9 is joined to at least one outer surface of the side wall portion 3 (side wall surface 3 a) of the convex curved portion 7 and the side wall surface 3 a of the concave curved portion 8. The CFRP member 9 is joined to the side wall portion 3 to reinforce the thickness direction of the side wall portion 3. The method for joining the CFRP member 9 to the side wall 3 is not particularly limited, but is attached to the side wall 3 using, for example, an adhesive resin. In addition, when the CFRP member 9 is affixed to the side wall part 3 with adhesive resin, if the cross section of the side wall part 3 of the said part is observed, an adhesive resin layer will exist between the side wall part 3 and the CFRP member 9. Can be confirmed. The bonding method of the FRP member including the CFRP member 9 and the resin used for bonding will be described later.

The front lower arm 1 of the present embodiment is configured as described above. For example, in the front lower arm 1 in which the CFRP member 9 is joined to the convex curved portion 7, for example, the side wall portion 3 opens outwardly due to vibration during vehicle travel, and the angle formed between the top surface of the top plate portion 2 and the side wall surface 3 a. 5 increases, a force in the contraction direction acts on the convex curved portion 7 as shown in FIG. In the present embodiment, the “shrink direction” refers to the convex curved portion 7 and the side wall portion 3 toward the middle point of the convex curved portion 7 in the cross-sectional view when the convex curved portion 7 is viewed in a cross section perpendicular to the side wall portion 3. This indicates the direction in which the boundary with the plane portion approaches. FIG. 5 is an enlarged view of a portion where the CFRP member 9 of the convex curved portion 7 according to the present embodiment is joined as viewed from the extending direction D (downward direction in FIG. 3) of the side wall portion 3. In this FIG. 5, the force which acts on the convex curve part 7 when the side wall part 3 opens outside is shown. At this time, in the front lower arm 1 of the present embodiment, since the CFRP member 9 is joined to the convex curved portion 7, even if a force in the contracting direction acts on the convex curved portion 7, the force is the convex curved portion. 7 as well as the CFRP member 9. For this reason, the CFRP member 9 generates a reaction force that inhibits deformation of the convex curved portion 7 in the contraction direction. For this reason, the rigidity in the convex curve part 7 in which the CFRP member 9 is joined to the side wall surface 3a is increased, and deformation of the convex curve part 7 due to vibration is suppressed.

On the other hand, for example, when the side wall portion 3 falls inward due to vibration during traveling of the automobile and the angle formed between the top surface of the top plate portion 2 and the side wall surface 3a becomes small, the convex curved portion 7 is formed as shown in FIG. The force in the direction of elongation acts. The “extension direction” in the present embodiment refers to the convex curve portion 7 and the side wall portion 3 toward the middle point of the convex curve portion 7 in the cross-sectional view when the convex curve portion 7 is viewed in a cross section perpendicular to the side wall portion 3. The direction in which the boundary with the plane part of is separated. FIG. 6 is an enlarged view of a portion where the CFRP member 9 of the convex curved portion 7 according to the present embodiment is joined as viewed from the extending direction D (downward direction in FIG. 3) of the side wall portion 3. In this FIG. 6, the force which acts on the convex curved part 7 when the side wall part 3 falls inward is shown. At this time, in the front lower arm 1 of the present embodiment, since the CFRP member 9 is joined to the convex curved portion 7, even if a force in the extending direction acts on the convex curved portion 7, the force is the convex curved portion. 7 as well as the CFRP member 9. For this reason, the CFRP member 9 generates a reaction force that inhibits deformation of the convex curved portion 7 in the extending direction. For this reason, the rigidity in the convex curve part 7 in which the CFRP member 9 is joined to the side wall surface 3a is increased, and deformation of the convex curve part 7 due to vibration is suppressed.

As described above, according to the front lower arm 1 of the present embodiment, the CFRP member 9 is joined to the convex curved portion 7 so that the convex curved portion is formed regardless of whether the side wall portion 3 opens outward or falls inward due to vibration. The deformation of the portion 7 can be suppressed. The outward opening of the side wall 3 in the convex curved portion 7 and the inner side collapse are accompanied by deformation of the convex curved portion 7, but in the front lower arm 1 of this embodiment, such convex curved portion 7 Since the deformation can be suppressed, as a result, the side wall 3 can be prevented from opening outward or falling inward. Thereby, the stress which acts on the root of the side wall part 3 of the convex curved part 7 at the time of vibration generation becomes small, and it becomes possible to suppress the occurrence of fatigue cracks at the root of the side wall part 3.

In addition, the joining position of the CFRP member 9 with respect to the side wall surface 3a of the convex curved portion 7 is not particularly limited. Regardless of the position of the CFRP member 9 joined to the side wall surface 3a, the portion where the CFRP member 9 is joined to the side wall surface 3a inhibits deformation of the convex curved portion 7 caused by vibration as shown in FIGS. Therefore, the deformation of the convex curved portion 7 can be suppressed as compared with the case where the CFRP member 9 is not provided. However, the deformation of the convex curved portion 7 is likely to occur at the distal end portion in the extending direction D of the side wall portion 3. Therefore, for example, as shown in FIG. 7, it is more preferable that the CFRP member 9 is joined to at least the tip 3 b of the convex curved portion 7. Thereby, since the deformation | transformation of this front-end | tip part 3b is suppressed, the deformation | transformation of the convex curve part 7 can be suppressed more effectively.

Further, as shown in FIGS. 3 and 4, the CFRP member 9 is preferably joined so as to include the central portion 7 a in the circumferential direction C of the convex curved portion 7. The “center portion 7a” is a portion located at the center of the region in the circumferential direction C of the convex curved portion 7, and when the convex curved portion 7 is viewed from the extending direction D of the side wall portion 3 as shown in FIG. The distances from the portion 7a to both ends of the region in the circumferential direction C of the convex curved portion 7 are equal to each other. The deformation of the convex curved portion 7 at the time of vibration is likely to occur at the central portion 7a. For this reason, the CFRP member 9 is joined to the central portion 7a in the circumferential direction C of the convex curved portion 7, so that the deformation of the convex curved portion 7 at the time of vibration is easily suppressed.

Moreover, it is preferable that the CFRP member 9 is joined so as to include the maximum curvature portion 7 b in the circumferential direction C of the convex curved portion 7. The “curvature maximum portion 7 b” is a portion where the radius of curvature R in the region of the convex curved portion 7 is minimized when the convex curved portion 7 is viewed from the extending direction D of the side wall portion 3. In the present embodiment, the central portion 7a is included in the maximum curvature portion 7b. The deformation of the convex curved portion 7 at the time of vibration is likely to occur at the maximum curvature portion 7b in the circumferential direction C where the curvature radius R is small. For this reason, the CFRP member 9 is joined to the maximum curvature portion 7b in the circumferential direction C of the convex curved portion 7, so that deformation of the convex curved portion 7 when vibration is generated can be easily suppressed. This effect is further increased when the radius of curvature R of the convex curved portion 7 viewed from the extending direction D of the side wall portion 3 is 250 mm or less.

The length L ₁ in the circumferential direction C of the CFRP member 9 is preferably 80% or more with respect to the length L ₂ in the circumferential direction C of the convex curved portion 7. Thereby, the effect which suppresses a deformation | transformation of the convex curve part 7 at the time of a vibration generation can be heightened. Also has a circumferential direction C of the length L ₂ with respect to the more than 80% of the length L ₁ of the convex curved portion 7, and includes a central portion 7a in the circumferential direction C of the convex curved portion 7 as described above By joining the CFRP member 9 as described above, the effect of suppressing the deformation of the convex curved portion 7 can be further enhanced. The thickness of the CFRP member 9 is not particularly limited. The thickness of the CFRP member 9 is appropriately changed according to the shape of the convex curved portion 7, the surrounding space, and the like, and is, for example, 1 to 5 mm.

Further, although the fiber orientation of the CFRP member 9 is not particularly limited, it is preferably within ± 30 ° with respect to the circumferential direction C viewed from the side wall surface 3 a of the convex curved portion 7. Thereby, the effect which suppresses a deformation | transformation of the convex curve part 7 at the time of a vibration generation can be heightened. Such a CFRP member 9 can be realized by using, for example, a UD (Unidirectional) material.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

For example, the CFRP member 9 may be joined to a convex curved portion 7 different from the convex curved portion 7 described in the above embodiment as shown in FIG. Even in this case, deformation at the time of vibration is suppressed in the convex curved portion 7 to which the CFRP member 9 is joined.

In the above description, the CFRP member 9 is joined to the convex curved portion 7, but the CFRP member 9 may be joined to the concave curved portion 8 as shown in FIG. 9. In this case, similarly to the case where the CFRP member 9 is joined to the convex curved portion 7 as in the above embodiment, the rigidity of the concave curved portion 8 can be increased, and the concave curved portion 8 can be deformed when vibration is generated. Can be suppressed.

For example, when the side wall 3 is opened to the outside due to vibration during traveling of the automobile and the angle formed between the top surface of the top plate 2 and the side wall 3a is increased, a force in the extending direction acts on the concave curved portion 8. At this time, if the CFRP member 9 is bonded to the concave curved portion 8, a reaction force that inhibits deformation of the concave curved portion 8 in the extending direction is generated. For this reason, the rigidity in the concave curved portion 8 in which the CFRP member 9 is joined to the side wall surface 3a is increased, and deformation of the concave curved portion 8 due to vibration is suppressed.

On the other hand, for example, when the side wall portion 3 falls inward due to vibration during traveling of the automobile and the angle formed between the top surface of the top plate portion 2 and the side wall surface 3a becomes small, a force in the contraction direction acts on the concave curved portion 8. . At this time, if the CFRP member 9 is joined to the concave curved portion 8, a reaction force that inhibits deformation of the concave curved portion 8 in the contraction direction is generated. For this reason, the rigidity in the concave curved portion 8 in which the CFRP member 9 is joined to the side wall surface 3a is increased, and deformation of the concave curved portion 8 due to vibration is suppressed.

As described above, when the CFRP member 9 is joined to the concave curved portion 8, deformation of the concave curved portion 8 can be suppressed regardless of whether the side wall portion 3 opens outward or falls down due to vibration. The outward opening of the side wall portion 3 or the inner side collapse of the concave curved portion 8 is accompanied by deformation of the concave curved portion 8, but the CFRP member 9 is joined to the concave curved portion 8, so that Since the deformation of the concave curved portion 8 can be suppressed, as a result, the side wall portion 3 can be prevented from opening outward or falling inward. Thereby, the stress which acts on the root of the side wall part 3 of the concave curved part 8 at the time of vibration generation becomes small, and it becomes possible to suppress the occurrence of fatigue cracks at the base of the side wall part 3.

The CFRP member 9 may be joined to both the convex curved portion 7 and the concave curved portion 8. Further, when there are a plurality of convex curved portions 7 and concave curved portions 8, they may be joined to all the convex curved portions 7 and concave curved portions 8, but fatigue cracks occur from the viewpoint of weight reduction. It is preferable to be joined to the convex curved portion 7 or the concave curved portion 8 of the easy portion or both. Although the location where fatigue cracks are likely to occur differs depending on the shape of the front lower arm 1, for example, by estimating a portion where fatigue cracks are likely to occur from a plurality of convex curved portions 7 or concave curved portions 8 by simulation, CFRP The joining position of the member 9 may be determined.

Even when the CFRP member 9 is joined to the concave curved portion 8, the CFRP member 9 is joined to at least the distal end portion 3 b of the concave curved portion 8 in the same manner as when the CFRP member 9 is joined to the convex curved portion 7. It is preferable. Similarly, the CFRP member 9 is preferably joined so as to include the central portion in the circumferential direction C of the concave curved portion 8. Similarly, the CFRP member 9 is preferably joined so as to include the maximum curvature portion in the circumferential direction C of the concave curved portion 8. Similarly, it is more preferable that the radius of curvature of the concave curved portion 8 when viewed from the extending direction D of the side wall portion 3 is 250 mm or less. Similarly, the length of the CFRP member 9 in the circumferential direction C is preferably 80% or more with respect to the length of the concave curved portion 8 in the circumferential direction C. Similarly, the fiber orientation of the CFRP member 9 is preferably within ± 30 ° with respect to the circumferential direction C as viewed from the side wall surface 3 a of the concave curved portion 8.

Further, in the description of the above embodiment, the structure of the CFRP member 9 as the reinforcing member joined to the convex curved portion 7 or the concave curved portion 8 is joined to the outside of the side wall surface 3a or the tip portion 3b. However, the bonding position of the CFRP member 9 in the present invention is arbitrary, and can be bonded to any part of the convex curved part 7 and the concave curved part 8. FIG. 10 is a schematic explanatory view showing a configuration of a CFRP member 9 according to another embodiment of the present invention, and shows an enlarged cross section in the circumferential direction C of the joint portion of the CFRP member 9.

As shown in FIG. 10A, the CFRP member 9 may be joined to both the inside and the outside of the side wall portion 3, for example. As shown in FIG. 10B, the CFRP member 9 may be joined so as to cover the end surface portion 3 c of the side wall portion 3 in addition to both the inside and the outside of the side wall portion 3. By bonding the CFRP member 9 to both the inside and the outside of the side wall portion 3, it is possible to further enhance the effect of suppressing the deformation of the convex curved portion 7 and the concave curved portion 8 when vibration is generated. Further, by joining the end face portion 3c so as to be covered with the CFRP member 9, end face fatigue and corrosion resistance of the side wall portion 3 can be improved.

In the above description, the CFRP member 9 has been described as an example of the reinforcing member joined to at least one of the convex curved portion 7 and the concave curved portion 8, but the reinforcing member is, for example, GFRP (glass fiber reinforced resin). A GFRP member made of Further, the reinforcing member may be a resin member made of a resin other than the resin described above. Moreover, the build-up part formed in the side wall surface 3a may be sufficient. That is, the material of the reinforcing member is not particularly limited as long as it is a member separate from the front lower arm 1 and can be joined to the side wall surface 3a. From the viewpoint of weight reduction and specific rigidity improvement, it is preferable to use a CFRP member as the reinforcing member. Specific examples of the type and joining method of the FRP member when the reinforcing member is an FRP member will be described later. The reinforcing member may be joined to the inside of the side wall surface 3a. Even in this case, it is possible to suppress the deformation of the convex curve portion or the concave curve portion at the time of vibration by the same mechanism as when the reinforcing member is joined to the outside of the side wall surface 3a.

Note that the part having the side wall portion 3 in the curved portion is not limited to the front lower arm 1 of the automobile described in the above embodiment, and for example, at least one of a rear lower arm, a trailing arm, an upper arm, a front subframe, and a rear subframe. Or a single component. Further, the part having the side wall part 3 in the curved part may be another underbody part. Moreover, the part which has the side wall part 3 in a curved part is not limited to the suspension part of a motor vehicle, The motor vehicle part attached to other parts other than a suspension part may be sufficient. Moreover, the component which has the side wall part 3 in a curved part is not limited to a motor vehicle component, The component used for another field may be sufficient.

Since the part in which the side wall portion 3 having at least one of the convex curved portion 7 and the concave curved portion 8 is formed can be exposed to some vibrations without being limited to the use, the root of the side wall portion 3 is caused by the stress caused by the vibration. There is a risk of fatigue cracking. On the other hand, if a reinforcing member is joined to at least one of the convex curved portion 7 and the concave curved portion 8, the occurrence of fatigue cracks in the portion is suppressed, and the reinforcing member is provided. Compared with parts that are not provided, the occurrence of fatigue cracks at the base of the side wall 3 can be suppressed.

<Type of FRP member>
The FRP member that can be used as the reinforcing member means a fiber reinforced resin member that is composed of a matrix resin and a reinforced fiber material that is contained in the matrix resin and combined.

As the reinforcing fiber material, for example, carbon fiber or glass fiber can be used. In addition, boron fiber, silicon carbide fiber, aramid fiber, or the like can be used as the reinforcing fiber material. In the FRP used for the FRP member, examples of the reinforcing fiber base material used as the base material of the reinforcing fiber material include, for example, a nonwoven fabric base material using chopped fibers, a cloth material using continuous fibers, and a unidirectional reinforcing fiber base material (UD). Material) etc. can be used. These reinforcing fiber bases can be appropriately selected according to the orientation of the reinforcing fiber material.

The CFRP member is an FRP member using carbon fiber as a reinforcing fiber material. As the carbon fiber, for example, a PAN-based or pitch-based one can be used. By using the carbon fiber, the strength with respect to weight can be improved efficiently.

The GFRP member is an FRP member using glass fiber as a reinforcing fiber material. Although it is inferior to a carbon fiber in mechanical characteristics, it can suppress the electric corrosion of a metal member.

Both the thermosetting resin and the thermoplastic resin can be used as the matrix resin used for the FRP member. Examples of the thermosetting resin include epoxy resins, unsaturated polyester resins, and vinyl ester resins. Thermoplastic resins include polyolefins (polyethylene, polypropylene, etc.) and acid-modified products thereof, polyamide resins such as nylon 6 and nylon 66, thermoplastic aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyethersulfone. And polyphenylene ether and modified products thereof, polyarylate, polyetherketone, polyetheretherketone, polyetherketoneketone, styrene resins such as vinyl chloride and polystyrene, and phenoxy resin. The matrix resin may be formed of a plurality of types of resin materials.

In consideration of application to metal members, it is preferable to use a thermoplastic resin as the matrix resin from the viewpoint of workability and productivity. Furthermore, the density of the reinforcing fiber material can be increased by using a phenoxy resin as the matrix resin. Moreover, since the phenoxy resin has a molecular structure very similar to that of an epoxy resin that is a thermosetting resin, the phenoxy resin has a heat resistance comparable to that of an epoxy resin. Moreover, application to a high temperature environment is also possible by further adding a curing component. In the case of adding a curable component, the addition amount may be appropriately determined in consideration of the impregnation property to the reinforcing fiber material, the brittleness of the FRP member, the tact time, the workability, and the like.

<Adhesive resin layer>
When the reinforcing member is formed of an FRP member or the like, an adhesive resin layer is provided between the FRP member and the metal member (the front lower arm 1 in the above embodiment), and the FRP member and the metal member are joined by the adhesive resin layer. May be.

The type of the adhesive resin composition that forms the adhesive resin layer is not particularly limited. For example, the adhesive resin composition may be either a thermosetting resin or a thermoplastic resin. The kind of thermosetting resin and thermoplastic resin is not particularly limited. For example, as thermoplastic resins, polyolefins and acid-modified products thereof, polystyrene, polymethyl methacrylate, AS resin, ABS resin, thermoplastic aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyimide, polyamide, polyamide Use one or more selected from imide, polyetherimide, polyethersulfone, polyphenylene ether and modified products thereof, polyphenylene sulfide, polyoxymethylene, polyarylate, polyetherketone, polyetheretherketone, and polyetherketoneketone can do. Moreover, as a thermosetting resin, 1 or more types chosen from an epoxy resin, a vinyl ester resin, a phenol resin, and a urethane resin can be used, for example.

The adhesive resin composition can be appropriately selected according to the characteristics of the matrix resin constituting the FRP member, the characteristics of the reinforcing member, or the characteristics of the metal member. For example, the adhesiveness is improved by using a resin having a polar functional group or a resin subjected to acid modification as the adhesive resin layer.

Thus, the adhesion between the FRP member and the metal member can be improved by adhering the FRP member to the metal member using the above-described adhesive resin layer. If it does so, the deformation | transformation followable | trackability of an FRP member when a load is input with respect to a metal member can be improved. In this case, the effect of the FRP member on the deformed body of the metal member can be more reliably exhibited.

The form of the adhesive resin composition used to form the adhesive resin layer can be, for example, a liquid such as powder or varnish, or a solid such as a film.

Also, a crosslinkable adhesive resin composition may be formed by blending a crosslinkable curable resin and a crosslinker into the adhesive resin composition. Thereby, since the heat resistance of the adhesive resin composition is improved, application under a high temperature environment becomes possible. As the cross-linking curable resin, for example, a bifunctional or higher functional epoxy resin or a crystalline epoxy resin can be used. Moreover, an amine, an acid anhydride, etc. can be used as a crosslinking agent. Moreover, various additives, such as various rubber | gum, an inorganic filler, a solvent, may be mix | blended with the adhesive resin composition in the range which does not impair the adhesiveness and physical property.

The compounding of the FRP member into the metal member can be realized by various methods. For example, it can be obtained by adhering an FRP forming prepreg which is an FRP member or an FRP molding prepreg thereof and a metal member with the above-described adhesive resin composition, and solidifying (or curing) the adhesive resin composition. . In this case, for example, the FRP member and the metal member can be combined by performing thermocompression bonding.

The above-mentioned adhesion of FRP or FRP molding prepreg to a metal member can be performed before molding, during molding, or after molding. For example, after forming a metal material as a workpiece into a metal member, FRP or FRP molding prepreg may be bonded to the metal member. Alternatively, after FRP or FRP molding prepreg is bonded to the workpiece by thermocompression bonding, the workpiece to which the FRP member is bonded may be molded to obtain a composite metal member. If the matrix resin of the FRP member is a thermoplastic resin, it is possible to perform a bending process or the like on the portion to which the FRP member is bonded. In addition, when the matrix resin of the FRP member is a thermoplastic resin, composite batch molding in which the thermocompression bonding step and the molding step are integrated may be performed.

In addition, the joining method of the FRP member and the metal member is not limited to the above-described adhesion by the adhesive resin layer. For example, the FRP member and the metal member may be mechanically joined. More specifically, a fastening hole is formed at a position corresponding to each of the FRP member and the metal member, and these are fastened through the hole by a fastening means such as a bolt or a rivet. The member may be joined. In addition, the FRP member and the metal member may be joined by a known joining means. Further, the FRP member and the metal member may be joined in a composite manner by a plurality of joining means. For example, the adhesion by the adhesive resin layer and the fastening by the fastening means may be used in combination.

As the reinforcing member, various materials can be used in addition to the FRP member. For example, the reinforcing member may be formed of a resin composition other than the resin composition described above, such as a foamable resin formed of rigid polyurethane foam or the like. Moreover, the reinforcing member may be formed by overlaying as the overlaying part. In this case, the type of metal used for overlaying is appropriately determined in view of the characteristics of the metal member with the base material. Moreover, the joining method with a metal member is not restricted to welding, A various appropriate joining method can be used.

<Metal member and its surface treatment>
The metal member according to the present invention may be plated. Thereby, corrosion resistance improves. In particular, it is more suitable when the metal member is a steel material. The type of plating is not particularly limited, and known plating can be used. For example, as galvanized steel sheets (steel materials), hot dip galvanized steel sheets, galvannealed steel sheets, Zn—Al—Mg alloy plated steel sheets, aluminum plated steel sheets, electrogalvanized steel sheets, electric Zn—Ni alloy plated steel sheets, etc. Can be used.

Further, the metal member may have a surface coated with a film called chemical conversion treatment. Thereby, corrosion resistance improves more. As the chemical conversion treatment, a generally known chemical conversion treatment can be used. For example, as the chemical conversion treatment, zinc phosphate treatment, chromate treatment, chromate-free treatment or the like can be used. Further, the film may be a known resin film.

In addition, the metal member may be one that is generally painted. Thereby, corrosion resistance improves more. As the coating, a known resin can be used. For example, as a coating, an epoxy resin, a urethane resin, an acrylic resin, a polyester resin, or a fluorine resin can be used as a main resin. Moreover, generally well-known pigment may be added to the coating as needed. The coating may be a clear coating to which no pigment is added. Such coating may be applied to the metal member in advance before the FRP member is combined, or may be applied to the metal member after the FRP member is combined. Alternatively, the FRP member may be combined after the metal member has been painted in advance, and then painted. The paint used for painting may be a solvent-based paint, a water-based paint, a powder paint, or the like. In general, a known method can be applied as a method of painting. For example, electrodeposition coating, spray coating, electrostatic coating, immersion coating, or the like can be used as a coating method. Since electrodeposition coating is suitable for coating the end face and gap portion of a metal member, it is excellent in corrosion resistance after coating. Moreover, coating film adhesion improves by performing generally well-known chemical conversion treatments, such as a zinc phosphate process and a zirconia process, on the surface of a metal member before coating.

<Stress simulation (A)>
Stress simulation was performed on a part having a side wall portion in a curved portion according to the present invention. The analysis model is a front lower arm 1 shown in FIG. 11, and a CFRP member made of CFRP having a four-layer structure at a convex curved portion 7 between the first vehicle body mounting side end 4 and the second vehicle body mounting side end 5. 9 is affixed.

The CFRP member 9 is pasted so as to cover the entire side wall surface of the convex curved portion 7, and the radius of curvature of the convex curved portion 7 to which the CFRP member 9 is pasted is about 50 mm. The thickness of the CFRP member 9 is 3 mm, and the plate thickness of the front lower arm main body (base material) is 2.3 mm. Three types of analysis models are prepared: a model in which the fiber direction of CFRP coincides with the circumferential direction C, a model in which the fiber direction is orthogonal to the circumferential direction C, and a model in which the CFRP member 9 is not attached. The steel type and shape of the front lower arm body (base material) in each analysis model are the same.

In this simulation, assuming a bending deformation from the front to the rear in the vehicle length direction, a load of 15 kN was input in the arrow direction of the wheel mounting side end portion 6 shown in FIG. The first vehicle body attachment side end 4 and the second vehicle body attachment side end 5 are restrained. The results of stress simulation performed under such conditions are shown in Table 1 below. In this simulation, the evaluation was performed by paying attention to the maximum principal stress at the base of the side wall portion 3 of the convex curved portion 7 between the first vehicle body attachment side end portion 4 and the second vehicle body attachment side end portion 5. Do.

As shown in Table 1, in Example 1 and Example 2 in which the CFRP member 9 is attached to the convex curved portion 7, the maximum principal stress is smaller than that in Comparative Example 1 in which the CFRP member 9 is not attached. ing. That is, even if a stress is repeatedly applied to the base of the side wall 3 of the convex curved portion 7 due to vibration, the stress is smaller than when the CFRP member 9 is not attached. Thus, the occurrence of fatigue cracks is suppressed.

<Stress simulation (B)>
Next, an analysis model shown in FIG. 12 was created and a stress simulation was performed. In the analysis model of this simulation, a CFRP member 9 made of CFRP having a four-layer structure is attached to a convex curved portion 7 between the first vehicle body attachment side end 4 and the wheel attachment side end 6.

The CFRP member 9 is pasted so as to cover the entire side wall surface of the convex curved portion 7, and the radius of curvature of the convex curved portion 7 to which the CFRP member 9 is pasted is 250 mm. The thickness of the CFRP member 9 is 3 mm, and the plate thickness of the front lower arm main body (base material) is 2.3 mm. Three types of analysis models are prepared: a model in which the fiber direction of CFRP coincides with the circumferential direction C, a model in which the fiber direction is orthogonal to the circumferential direction C, and a model in which the CFRP member 9 is not attached. The steel type and shape of the front lower arm body (base material) in each analysis model are the same.

In this simulation, assuming a bending deformation from the rear to the front in the vehicle length direction, a load of 15 kN was input in the arrow direction of the wheel mounting side end 6 shown in FIG. The first vehicle body attachment side end 4 and the second vehicle body attachment side end 5 are restrained. The results of the stress simulation performed under such conditions are shown in Table 2 below. In this simulation, the evaluation is performed by paying attention to the maximum principal stress at the base of the side wall portion 3 of the convex curved portion 7 between the first vehicle body attachment side end 4 and the wheel attachment side end 6.

As shown in Table 2, in Example 3 and Example 4 in which the CFRP member 9 is adhered to the convex curved portion 7, the maximum principal stress is smaller than that in Comparative Example 2 in which the CFRP member 9 is not adhered. ing. That is, even if a stress is repeatedly applied to the base of the side wall 3 of the convex curved portion 7 due to vibration, the stress is smaller than the stress when the CFRP member 9 is not attached, and therefore the CFRP member 9 is attached. The occurrence of fatigue cracks is suppressed as compared with the case where there is no.

Further, when Example 3 and Example 4 are compared, the maximum principal stress is smaller in Example 4 in which the fiber direction of CFRP coincides with the circumferential direction C. According to the result of this simulation, it is possible to reduce the maximum principal stress by sticking the CFRP member 9 to the convex curved portion 7 regardless of the fiber direction of the CFRP. It is shown that the maximum principal stress can be further reduced by aligning in the circumferential direction C. According to the result of this simulation, it is presumed that the preferred fiber direction of CFRP is within ± 30 ° with respect to the circumferential direction C. In this case, the effect of suppressing the occurrence of fatigue cracks at the base of the side wall 3 is enhanced. be able to. Further, when GFRP is used instead of CFRP, the influence of the fiber direction is the same as that of CFRP. Therefore, if the fiber direction of GFRP is within ± 30 ° with respect to the circumferential direction C, the root of the side wall 3 is The effect of suppressing the occurrence of fatigue cracks can be enhanced.

The present invention can be used as a front lower arm of an automobile.

DESCRIPTION OF SYMBOLS 1 Front lower arm 2 Top plate part 3 Side wall part 3a Side wall surface 3b Tip part 4 1st vehicle body attachment side edge part 5 Car body attachment side edge part 6 Wheel attachment side edge part 7 Convex curve part 7a Center of convex curve part Part 7b Maximum curvature of convex curved portion 8 Concave curved portion 9 CFRP member 50 Front lower arm C Side wall circumferential direction D Side wall extending direction R Curvature radius L ₁ CFRP member circumferential length L ₂ Convex curved portion Circumferential length

Claims

A top plate part and a side wall part formed by bending the top plate part around the top plate part, and a component having an open cross section in a direction perpendicular to the top plate part,
The side wall portion includes a curved portion that is concave or convex in the component inner direction when viewed from a direction perpendicular to the top plate portion, and is curved with a curvature radius of 300 mm or less.
A component, wherein a reinforcing member joined to the side wall portion is provided on at least a part of the curved portion.
The component according to claim 1, wherein the reinforcing member is provided at least at a front end portion in the extending direction of the side wall portion.
The component according to claim 1, wherein the reinforcing member is provided in a curved portion that is curved with a curvature radius of 20 mm or more and 250 mm or less when viewed from a direction perpendicular to the top plate portion.
The said reinforcing member is provided in the curved part which curves when the curvature radius seen from the direction perpendicular | vertical to the said top plate part is 4 times or more and 375 times or less of the plate | board thickness of the said side wall part, It is characterized by the above-mentioned. 2. The component according to 2.
5. The reinforcing member according to claim 1, wherein the reinforcing member is provided so as to include a portion having a minimum curvature radius when viewed from a direction perpendicular to the top plate portion in the curved portion. The parts described in.
The length of the reinforcing member provided in the bending portion in the circumferential direction of the bending portion is 80% or more of the length of the bending portion. The parts described in.
The component according to any one of claims 1 to 5, wherein a thickness of the side wall portion is 5.0 mm or less.
The part according to any one of claims 1 to 7, wherein the reinforcing member is a resin member made of resin.
The component according to claim 8, wherein the resin is FRP.
The component according to claim 9, wherein a fiber orientation of a reinforcing fiber material included in the FRP is within ± 30 ° with respect to a circumferential direction of the curved portion.
The component according to claim 9 or 10, wherein the FRP is CFRP.
The component according to claim 9 or 10, wherein the FRP is GFRP.
The component according to any one of claims 1 to 7, wherein the reinforcing member is a built-up portion.
The part according to any one of claims 1 to 13, wherein the part is an automobile part.
The part according to claim 14, wherein the automobile part is an undercarriage part.