JPH08112160A - Seat back frame structure of vehicle - Google Patents

Abstract

PURPOSE: To restrain stress concentration from being generated in a connecting part of left and right side parts and a top part to the possible minimum level even when a comparatively large load to rearward of a vehicle is applied to the top part. CONSTITUTION: A seat back frame 18 being an integral mold is composed of left and right side parts 24 and a top part 28 containing a corner part 26. Here, a gradually changing flange part 30D to gradually change a section modulus of a connecting part of both is arranged in a connecting part (a D line view part) to connect the side parts 24 and the corner part 26 to each other. Therefore, even when a comparatively large load to rearward of a vehicle is applied to the top part 28, stress concentration can be restrained from being generated in the connecting part of the left and right side parts 24 and the top part 28 to the possible minimum level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle seat back frame structure having a top portion including a pair of side portions and corner portions and formed in a substantially inverted U shape as a whole.

[0002]

2. Description of the Related Art Generally, a seat back of a vehicle seat is set to have a high strength to form a skeletal member and to support a headrest, and a seatback frame which is attached to the seatback frame to support an upper body of an occupant. The seat back pad and a skin material that covers the surface of the seat back pad are generally configured.

Although there are various structures of the seat back frame of the seat back described above, conventionally, the axis of the pipe is inverted U
There is a seat back frame configured by an upper frame provided by being bent in a letter shape and a pair of side frames of a press-molded product which are attached to the lower end portion of the upper frame by welding. With this configuration, since the seatback frame is composed of three parts, the number of parts is increased and the number of manufacturing steps is increased accordingly. A structure devised to solve this problem is disclosed in JP-A-6-70827, and the structure disclosed in this publication will be described below.

As shown in FIG. 16, in the structure disclosed in this publication, the seat back frame 140 is composed of an upper seat back frame 148 and a lower seat back frame 150. Among these, the upper seat back frame 148 includes a pair of wide side portions 152 arranged on the left and right, and the corner portion 1 extending upward from each upper end portion of these side portions 152.
Top portion 156 formed in a substantially inverted U shape including 54
And are integrally formed. The lower seat back frame 150 is welded to the rear surfaces of the lower end portions of the pair of side portions 152.

The upper seat back frame 148 will be described in more detail.
As shown in (A), it is formed in a substantially U-shaped cross section,
A concave bead 158 is formed at the center in the width direction. An opening 160 for reducing the weight is formed in the center of the bead 158. Also, the top part 15
The corner portion 154 of No. 6 is formed in a substantially C-shaped cross section as shown in FIG. 17 (B), and both end portions 154A are both bent toward the axial center side and arranged in proximity to each other. Has been done. Further, the headrest support portion 157 of the top portion 156 is formed in a substantially rectangular cross section as shown in FIG.
57A are both bent toward the shaft center side and are arranged close to each other.

The above-described upper seat back frame 14
In the case of manufacturing No. 8, the procedure is roughly as follows. First, FIG.
As shown in FIG. 8 (A), the base material 162 conforming to the developed shape of the upper seat back frame 148 is punched from the base material by press molding (pressing step). At this time, the beads 158 and the like of the side portion 152 are also manufactured.
Next, as shown in FIG. 18 (B), the punched base material 162 has predetermined portions (the side portion 152 and the top portion 1).
The connection portion [a portion] with 56, the portion [b portion] corresponding to the corner portion 154 of the top portion 156, and the crushed portion [c portion] where the headrest support portion 157 is formed are welded (welding process). Next, as shown in FIG. 18C, the pair of side portions 152 are bent in the same direction by bending. Then, as shown in FIG. 18D, the central portion of the top portion 156 is crushed to form the headrest support portion 157.

Therefore, according to the above structure, since the upper seat back frame 148 is integrally formed, an increase in the number of parts can be prevented and an increase in the number of manufacturing steps due to the increase in the number of parts can be eliminated. .

[0008]

However, in the case of the structure disclosed in the above publication, the left and right side portions 15 are formed.
2 upper end portion (substantially U-shaped open cross section) and the top portion 15
Lower end of the corner portion 154 of 6 (closed circular cross section)
Since no consideration is given to the method of connection with the, there is a problem in that the change in the section modulus at the connecting portion (the portion viewed from the arrow A in FIG. 16) is large. Therefore, when a relatively large load to the rear of the vehicle is applied to the top portion 156, stress is likely to be concentrated on the connecting portion, which is disadvantageous in terms of strength.

In consideration of the above facts, the present invention suppresses stress concentration as much as possible at the connecting portion between the left and right side portions and the top portion even when a relatively large load to the rear of the vehicle is applied to the top portion. It is an object to obtain a vehicle seat back frame structure that can be used.

[0010]

The present invention according to claim 1 is characterized in that a pair of wide side portions are provided in both side portions of the seat back in the width direction and extend in the height direction of the seat back.
For a vehicle that includes a top portion that is disposed along the width direction of the seat back in the upper end portion of the seat back and that is connected to a pair of side portions via corner portions, and is formed in a substantially inverted U shape as a whole In the seat back frame structure, a side portion is composed of a base portion forming a general surface of the side portion, a pair of side portions bent from both side portions of the base portion toward the inside of the seat back, and ends of each side portion. And a pair of flange portions that are bent substantially parallel to the center of the base portion, respectively, and a corner portion of the top portion and a corner base portion of a substantially C-shaped cross section. , A pair of corner ends bent from both ends of the corner base toward the center side of the corner base and abutting each other, and having a substantially circular closed cross section. A connecting portion that transitions from a side portion that is a cross section to a corner portion of the top portion that is the closed cross section is extended inward from the pair of flange portions and is connected to the pair of corner end portions and has an extension length. It is characterized in that a gradual change flange portion for gradually changing the size is provided.

According to a second aspect of the present invention, a pair of wide side portions arranged in both side portions in the width direction of the seat back and extending in the seat back height direction, and a width direction of the seat back in the upper end portion of the seat back. A vehicle seatback frame structure that is formed in a substantially inverted U shape as a whole, including a top portion that is disposed along the corner portion and that is connected to a pair of side portions via a corner portion, ,
A base portion that constitutes the general surface of the side portion, a pair of side portions that are bent from both sides of the base portion toward the inside of the seatback, and the ends of each side portion that are bent substantially parallel to the center of the base portion. And a pair of first flange portions each having a substantially U-shaped open cross section, and a corner portion of the top portion having a substantially C-shaped cross section, and a corner base portion from both end portions of the corner base portion. And a pair of first corner end portions that are respectively bent toward the center side of and are in contact with each other, and have a substantially circular closed cross section, and further, at least:
The pair of first flange portions are bent toward the base portion side, and the bending width of the pair of first portions is changed to the connecting portion that transitions from the side portion that is the open cross section to the corner portion of the top portion that is the closed cross section. It is characterized in that a pair of second flange portions that are substantially the same in width as one corner end portion and are connected to the pair of first corner end portions are provided.

According to a third aspect of the present invention, in addition to the second aspect of the present invention, the corner portion of the top portion is further bent from the pair of first corner end portions toward the corner base portion. Two corner end portions are provided, and the side portions are bent from the pair of second flange portions to the pair of side portions or the pair of first flange portions, respectively, and the bending width is the second corner end portion. And a third flange portion connected to the pair of second corner end portions is provided.

[0013]

According to the present invention as set forth in claim 1, the side portion has a predetermined open cross section and the corner portion of the top portion has a predetermined closed cross section. Since the connecting portion that transitions to the corner portion is provided with the gradually changing flange portion that extends inward from the pair of flange portions in the cross section, is connected to the pair of corner end portions, and the extension length gradually changes, the connecting portion The section modulus of does not change suddenly. Therefore, even if a relatively large load behind the vehicle acts on the top portion of the seat back frame,
Almost no stress is concentrated on the joint. In other words,
A smooth load transmission is achieved by continuously connecting the pair of flange portions and the pair of corner end portions by the gradually changing flange portion whose extension length gradually changes.

Moreover, by adopting the above construction, the section modulus increases by the amount of the gradually changing flange portion provided, which is advantageous in strength.

Further, since the corner ends are bent from both ends of the corner base toward the center of the corner base and abut each other, the corner ends are bent in the bending process and the crushing process when manufacturing the seat back frame. There is also no risk of the edge protruding outside the cross section. That is, it is possible to prevent the top portion from having a cross-section collapse in the manufacturing process. Therefore, in order to prevent this, it becomes possible to eliminate the welding work before the bending process and the crushing process, which are conventionally required.

According to the second aspect of the present invention, the side portion has a predetermined open cross section, the corner portion of the top portion has a predetermined closed cross section, and at least the side portion to the top portion. The connecting portion that transitions to the corner portion is respectively bent from the pair of first flange portions to the base portion side, and the bending width is substantially the same as the width of the pair of first corner end portions, and the pair of first corner ends. Since the pair of second flange portions connected to the portion is provided, the section modulus of the connecting portion does not change suddenly, and there is almost no change itself. For this reason, when a relatively large load is applied to the top portion of the seatback frame toward the rear of the vehicle, it is possible to further suppress the occurrence of stress concentration at the joint portion.

Moreover, in the present invention, since the bending width of the second flange portion is made substantially equal to the width of the first corner end portion, the section modulus is increased as compared with the present invention according to claim 1. Therefore, it is more advantageous in terms of strength.

In addition, in the present invention, since the pair of second flange portions are respectively bent from the pair of first flange portions toward the base portion side, even if the seat back receives a strong load at the time of collision, the second The edge of the flange does not interfere with the seat back pad. Therefore, it is possible to prevent the seat back pad from being damaged.

According to the present invention of claim 3, claim 2
In the present invention described, the corner portion of the top portion is provided with the second corner end portions that are respectively bent from the pair of first corner end portions to the corner base portion side, and the side portion is provided with the pair of second flange portions from the pair of second flange portions. Of the pair of the second corners, and the bending width is substantially the same as the width of the second corner end portion.
Since the third flange portion connected to the corner end portion is provided, in addition to the operation of the present invention according to claim 2, the section modulus is further increased by the amount of the second corner end portion and the third flange portion provided. be able to. Therefore, it is possible to obtain a high-strength seat back frame with a simple configuration without increasing the size of the seat back frame and complicating the manufacturing method.

[0020]

【Example】

[First Embodiment] The first embodiment will be described below with reference to FIGS. In these drawings, an arrow FR, which is shown appropriately, indicates the vehicle front side, an arrow UP indicates the vehicle upper side, and an arrow IN indicates the vehicle interior side. The first embodiment corresponds to an embodiment of the present invention described in claim 1.

FIG. 4 is an external perspective view of the front seat 10 of the automobile. As shown in this figure,
The front seat 10 includes a seat cushion 12 for seating an occupant, and a seat back 14 that supports the occupant's upper body by standing from the rear end of the seat cushion 12.
And a headrest 16 provided on the upper end of the seatback 14 to support the head of the occupant. Further, the seat back 14 is
Frame-shaped seat back frame 18 that constitutes the frame member of
A seat back pad 20 that is attached to the seat back frame 18 and is elastically deformable; and a skin material 22 that covers the surface of the seat back pad 20.

Next, with reference to FIGS. 1 to 3, a seat back frame 18 which is a skeletal member of the seat back 14 described above.
The structure of will be described in detail.

As shown in FIG. 1, the seatback frame 18 includes a pair of left and right side portions 24 which are disposed in both side portions of the seatback 14 in the width direction and extend in the height direction of the seatback 14, and the seatback 14. And a top portion 28 arranged along the width direction of the seat back 14 and connected to the pair of side portions 24 via a corner portion 26, and is generally inverted U-shaped as a whole. It is formed into a shape.

More specifically, the top portion 28
As shown in FIG. 3 (A), the corner portion 26 has a corner base portion 26A having a substantially C-shaped cross section, and a pair of ends bent from the both ends of the corner base portion 26A toward the center of the corner base portion 26A. And a corner end portion 26B of. Furthermore, a pair of corner ends 26B
Are abutted against each other, thereby forming a closed cross section of a tubular shape. The corner end portion 26B is located on the inner side of the seat back frame 18.

Further, the general portion 30 of the left and right side portions 24
In this case, as shown in FIG. 3 (B), a base portion 30A which is arranged with the surface including the seat front-back direction and the seat height direction as the surface direction and constitutes a general surface of the side portion, and the base portion 30A. A pair of side portions 30B bent substantially at right angles from both side portions (that is, both end portions in the front-rear direction side) to the inside of the seat back, and a tip portion of each side portion 30B to the base portion 30.
It is constituted by a pair of flange portions 30C that are bent substantially parallel to the center side of A. Therefore, the general portions 30 of the left and right side portions 24 have a substantially U-shaped open cross section. In addition, in the center of the base portion 30A, a bead 3 which is a recess having a substantially isosceles triangular shape in a side view.
2 is formed.

Further, the upper end of the top portion 28 (ie,
In the headrest support portion 34), as shown in FIG. 3C, the headrest support base portion 34A having an elliptical cross section.
And a pair of headrest support end portions 34B that are respectively bent from both ends of the headrest support base portion 34A toward the center side of the headrest support base portion 34A. Further, the pair of headrest support ends 34B are in contact with each other in the same manner as the pair of corner ends 26B of the corner portion 26 described above, thereby forming an elliptic tubular closed cross section. In addition, this headrest support end portion 34B
Are located on the inner side of the seatback frame 18.

Here, in the present embodiment, the general portion 30 of the side portion 24 which is the above-mentioned substantially U-shaped open cross section is further added.
A gradually changing flange portion 30D is formed at a connecting portion (a portion viewed from the arrow D in FIG. 1) that transitions from the corner portion 26 of the top portion 28 that is a closed cross section of a circular pipe shape. Hereinafter, the gradually changing flange portion 30D will be described in detail.

FIG. 2 shows the connecting portion in an enlarged state. As shown in this figure, a pair of gradually changing flange portions 30D extending inward from the pair of flange portions 30C in the cross section of the side portion 24 are integrally formed at the connecting portion of the side portion 24. This gradually changing flange 3
The upper end of 0D is connected to a pair of corner ends 26B located at the lower end of the top portion 28. Further, the extension length of the gradually changing flange portion 30D gradually increases from the lower end toward the upper end side, and in that sense, the extension length and thus the section modulus continuously and gradually change.

Further, the section L of the gradually changing flange portion 30D is formed.
Is a predetermined range (range shown in FIG. 2) in the connecting portion. However, it may be arbitrarily changed depending on the shape of the seatback frame 18. The pair of corner end portions 26B located on the upper end side of the gradually changing flange portion 30D are welded to prevent the cross section from opening. Further, the upper end position of the bead 32 formed on the base portion 30A of the side portion 24 is set slightly below the formation section L of the gradually changing flange portion 30D.

The operation of this embodiment will be described below while explaining the manufacturing process of the seatback frame 18.

First, as shown in FIG. 5A, a base material 36 conforming to the developed shape of the seatback frame 18 is punched out from a base material such as a steel plate (pressing process). At this time, the cross-sectional shape of the general portion 30 of the side portion 24 and the corner portion 26 of the top portion 28 and the cross-sectional shape of the connecting portion are formed in the process of pressing with the direction of the arrow in FIG. 24 beads 32 are also formed at the same time.

Next, as shown in FIG. 5B, the base material 36 manufactured by the pressing process is bent in the same direction at the corner portions 26 of the top portion 28 (bending process).

Next, as shown in FIG. 5C, a predetermined range of the upper end portion of the top portion 28 of the seat back frame 18 manufactured in the bending process is crushed (headrest crushing process). As a result, an elliptic tubular headrest support portion 34 is formed at the upper end of the top portion 28 as shown in FIG. 3 (C).

Thereafter, as shown in FIG. 5D, a predetermined portion of the seat back frame 18 manufactured in the headrest crushing step is welded (welding step). Specifically, the upper end of the connecting portion and the headrest support portion 34 of the top portion 28 are welded at two points. As a result, the seatback frame 18 having a substantially inverted U shape when viewed from the front is manufactured.

According to the seat back frame 18 of the present embodiment manufactured through the above manufacturing steps, the pair of left and right side portions 24 having a substantially U-shaped open cross section to the top portion 28 having a circular tubular closed cross section. Since the gradually changing flange portion 30D whose extension length gradually increases from the lower end to the upper end side is provided at the connecting portion that transitions to the corner portion 26, the side portion 24 and the top portion 28 are connected. The section modulus of the connecting portion can be gradually changed. That is,
There is no sudden change in the section modulus at the joint. Therefore, even if a relatively large load is applied to the top portion 28 of the seatback frame 18 toward the rear of the vehicle, it is possible to suppress the concentration of stress in the joint portion as much as possible. In other words, the pair of flange portions 30C of the side portion 24 and the top portion 28 are formed by the gradually changing flange portion 30D whose extension length gradually changes.
Since the pair of corner ends 26B are continuously connected, smooth load transmission can be performed.

Moreover, according to the present embodiment, since the section modulus of this portion can be increased by the provision of the gradually changing flange portion 30D, the strength can be improved.

The basic effects of this embodiment have been described above.
According to this embodiment, the following effects can be obtained.

First, the corner portion 26 of the top portion 28
In this case, the pair of corner end portions 26B are brought into contact with each other so as to form a closed cross section having a circular tubular shape, and the headrest support portion 3
In the case of No. 4, the pair of headrest supporting end portions 34B are brought into contact with each other so as to form a closed cross section of an elliptic tube.
The section modulus of 8 can be improved. Therefore, the rigidity of the top portion 28 can be improved.

Secondly, the pair of corner ends 26B are brought into contact (interference with each other) and the pair of headrest support ends 34B are brought into contact with each other (interference with each other). Time and seat back frame 18
It is possible to prevent the occurrence of cross-sectional collapse at the time of manufacturing (bending process and headrest crushing process) and to improve torsional rigidity. With respect to this point, conventionally, in order to secure the strength and prevent the cross-section from collapsing, the top portion 28 is subjected to the bending step and the headrest crushing step.
Although the corner portion 26 and the like are welded, according to the present embodiment, the same or higher strength can be obtained without welding the corner portion 26, so that the welding work can be reduced. it can.

Thirdly, since the second effect can be obtained, the welding work on the seatback frame 18 can be simultaneously performed at the same time as other welding work (for example, mounting work of the seatback spring 38). Can
It can contribute to cost reduction.

Fourthly, since the welding process can be collectively performed at the end, welding management becomes easy. Further, since the pair of corner end portions 26B and the headrest support end portion 34B are in contact with each other, that is, the surfaces are in a state of being face-to-face, the welding work is facilitated in this respect as well, and the welding management is also improved. It will be easier. [Second Embodiment] A second embodiment will be described below with reference to FIGS. 6 and 7. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The second embodiment corresponds to an embodiment of the present invention described in claim 2.

As shown in these figures, in this embodiment, instead of the gradually changing flange portion 30D provided at the connecting portion (see the portion indicated by the arrow D in FIG. 2), not the gradually changing but the equal width. The feature is that the second flange portion 30E is used. That is, as shown in FIGS. 7A and 7C, the corner portion 26 of the top portion 28 and the headrest support portion 34 have a closed cross section of a circular tube or an elliptic tube. Is similar to the above-described first embodiment. In the present embodiment, for convenience of description, the pair of flange portions 30C of the side portion 24 described above is referred to as "first flange portion 30".
"C", a pair of corner ends 26 of the top portion 28
B is referred to as “first corner end portion 26B”, and the pair of headrest support end portions 34B is referred to as “first headrest support end portion 3”.
4B ”.

However, as shown in FIG. 7 (B), the general portion 30 of the side portion 24 has an open cross-section with a substantially U-shaped cross section, but the pair of first flange portions 30.
These are further bent from C to the base portion 30A side to provide a pair of second flange portions 30E. The pair of second flange portions 30E are set to have substantially the same width direction dimension as the width direction dimension of the first corner end portion 26B of the corner portion 26 and the first headrest support end portion 34B of the headrest support portion 34, It is continuously provided not only at the connecting portion but also at the general portion 30. Therefore, the first headrest support end portion 30A of the headrest support portion 34 of the top portion 28
Is continuously connected to the first corner end portion 26B of the corner portion 26 as it is, and the first corner end portion 26B of the corner portion 26 is continuously extended as it is to the connecting portion of the side portion 24 and the general portion 30. Second flange 30
It is E.

According to the above configuration, the gradually changing flange portion 30D
Since the second flange portion 30E is used instead of the above, not only does the section modulus of the connecting portion not suddenly change, but also the change itself hardly occurs. Therefore, when a relatively large load to the rear of the vehicle is applied to the top portion 28 of the seatback frame 18, it is possible to further suppress the occurrence of stress concentration in the joint portion as compared with the first embodiment described above. it can.

Moreover, in the present embodiment, the second flange portion 30E is provided instead of the gradual change flange portion 30D at the connecting portion, and the constant width flange portion 30D is provided over the pair of side portions 24. Side part 2 including the connecting part
The section modulus of 4 can be increased. Therefore, according to this embodiment, it is possible to obtain the seat back frame 18 having higher strength.

Further, in the present embodiment, the pair of second flange portions 30E are provided by bending the pair of first flange portions 30C further toward the base portion 30A, so that they are strong in the event of a collision. Even when the seat back 14 receives the load, the problem that the edge of the second flange portion 30E projects outward in the cross section and interferes with the seat back pad does not occur. Therefore, it is possible to prevent the seat back pad 20 from being damaged without providing a separate component such as felt. Since the space in which the second flange portion 30E is provided is normally a dead space, there is no restriction on the space. [Third Embodiment] The third embodiment will be described below with reference to FIGS. The same components as those in the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted. In addition, the third embodiment is characterized by claim 3.
It corresponds to an embodiment of the invention described.

As shown in FIGS. 8 and 9, in this embodiment, the tip portions of the pair of second flange portions 30E of the side portion 24 are further bent toward the pair of side portions 30B at substantially right angles. The feature is that the three flange portions 30F are provided.

That is, as shown in FIG.
The first embodiment and the second embodiment described above in that the corner portion 26 of the top portion 28 has a substantially circular tubular closed cross section.
This is the same as the embodiment, except that the tip of the first corner end 26B is further bent toward the corner base 26A at a substantially right angle to provide the second corner end 26C. Similarly, as shown in FIG. 9C, the headrest support portion 34 of the top portion 28 is similar in that it has a substantially elliptic closed cross section, but the first headrest support end portion is the same. The difference is that the tip end portion of 34B is further bent at a substantially right angle to the headrest support base portion 34A side to provide a second headrest support end portion 34C.

On the other hand, as shown in FIG. 9B, in the side portion 24, the pair of second flange portions 30E has a further pair of tip portions over the entire general portion 30 including the connecting portion. The third flange portion 30F is formed by being bent substantially at a right angle to the side portion 30B side. This third flange portion 30F
The dimension in the width direction is set to be substantially the same as the dimension in the width direction of the second corner end portion 26C of the corner portion 26 of the top portion 28 and the second headrest support end portion 34C of the headrest support portion 34. Therefore, the second headrest support end portion 34C of the headrest support portion 34 of the top portion 28 is continuously connected to the second corner end portion 26C of the corner portion 26 as it is, and the second corner end portion 26C of the corner portion 26 is further connected. Is continuously extended as it is to the connecting portion of the side portion 24 and the general portion 30 to form the third flange portion 30F.

The cross-sectional shape of the above structure is manufactured as follows. First, the corner portion 26 of the top portion 28 will be described. As shown in FIG. 10A, a lower mold 52 having a shallow recess 50 and a protrusion 54 having a small protrusion amount.
A flat base material 58 is press-molded by using the upper mold 56 having the above. As a result, the second corner end portions 26C that bend in the same direction are first formed at both widthwise ends of the base material 58,
The primary processed product 60 is manufactured. Next, as shown in FIG. 10B, a relatively shallow recess 62 having a substantially semicircular cross section is formed.
Lower mold 64 and a relatively wide rectangular parallelepiped projection 6
Using the upper mold 68 having 6, the primary processed product 60 obtained
Press-mold. As a result, the central portion of the primary processed product 60 is pressed against the projected parts 66 until the pair of second corner end portions 26C come into contact with both side surfaces of the projected parts 66, and a substantially semicircular shaped secondary processed product 70 is manufactured. It Next, as shown in FIG. 10C, a lower mold 74 having a relatively deep recess 72 having a substantially semicircular cross section, a rectangular parallelepiped projection 76 having a relatively narrow width, and both sides of the projection 76 are provided. The obtained secondary processed product 70 is press-molded using the upper mold 80 having the inclined recessed portion 78. As a result, the pair of second corner end portions 26C descends along both side surfaces of the protrusion 76, and a part of the corner base portion 26A enters the inclined recessed portion 78 to form the first corner end portion 26B. As a result, a tertiary processed product 82 that is longer than the secondary molded product 70 is manufactured. After that, FIG.
As shown in (D), the obtained tertiary processed product 82 is press-molded using a lower mold 86 having a recess 84 having a semicircular cross section and an upper mold 90 having a recess 88 having a semicircular cross section. As a result, the pair of first corner end portions 26B come into contact with each other and are in close contact with each other, and the pair of second corner end portions 2
6C faces the corner base portion 26A, and the corner portion 26 is obtained.

Next, the general portion 30 of the side portion 24 will be described, but since it is basically the same as the corner portion 26, it will be briefly described. Although not shown in FIG. 11, the same steps as those shown in FIG. 10A are performed in this case as well. The primary processed product 60 obtained in this step is shown in FIG.
As shown in FIG. 1 (A), press molding is performed using a lower die 94 having a relatively shallow recess 92 having a rectangular cross section and an upper die 98 having a relatively wide rectangular parallelepiped projection 96.
As a result, the central portion of the primary processed product 60 remains in the protrusion 9 until the pair of third flange portions 30F abut on both side surfaces of the protrusion 96.
The secondary processed product 100 having a substantially U-shape is pressed by being pressed by 6. Next, as shown in FIG. 11B, a lower mold 104 having a recess 102 having a relatively deep rectangular cross section and an upper mold 108 having a rectangular parallelepiped projection 106 having a relatively narrow width are obtained. The secondary processed product 100 is press-molded.
As a result, the pair of third flange portions 30F are connected to the protrusions 106.
A pair of second flange portions 30E are formed on the bottom surface side of the upper mold 108 and the tertiary processed product 110 is manufactured while descending along both side surfaces. Thereafter, as shown in FIG. 11C, a lower mold 114 having a recess 112 having a rectangular cross section.
Using the upper die 118 having the narrow protrusions 116, the obtained tertiary processed product 110 is press-molded. As a result, the pair of third flange portions 30F moves toward the pair of side portions 30B, and the pair of second flange portions 30E are positioned on both side surfaces of the protrusion 116, so that the general portion 30 of the side portion 24 is formed. can get.

With the above structure, the same operational effect as that of the second embodiment described above can be obtained. Furthermore, in this embodiment,
Since the second corner end portion 26C and the second headrest support end portion 34C are newly provided in the top portion 28, and the third flange portion 30F is newly provided in the side portion 24,
The section modulus can be increased accordingly. Therefore, according to the present embodiment, it is possible to obtain the seat back frame 18 having higher strength without increasing the size of the seat back frame 18 and complicating the manufacturing method. [Fourth Embodiment] A fourth embodiment will be described below with reference to FIGS. The same components as those in the first to third embodiments are designated by the same reference numerals and the description thereof will be omitted. Further, the fourth embodiment corresponds to an embodiment of the present invention described in claim 3.

As shown in FIGS. 12 and 13, in the present embodiment, the third flange portion 30G (the hemming portion) is mainly formed by further folding back the tip portions of the pair of second flange portions 30E of the side portion 24 and closely contacting them. ) Is the feature.

That is, as shown in FIG. 13 (A), the corner portion 26 of the top portion 28 has a substantially circular tube-shaped closed cross section.
The third embodiment is similar to the third embodiment, except that the tip of the first corner end portion 26B is further folded back and brought into close contact with the second corner end portion 26D, which is a hemming portion. . Similarly, as shown in FIG. 13 (C), the headrest support portion 34 of the top portion 28 is similar in that it has a substantially elliptic tubular closed cross section, but the first headrest support end portion is the same. The second end, which is a hemming portion, is formed by further bending the tip end of 34B and closely contacting it.
The difference is that a headrest support end portion 34D is provided.

On the other hand, as shown in FIG. 13B, in the side portion 24, the tip portions of the pair of second flange portions 30E are further folded back over the entire general portion 30 including the connecting portion. The third flange portion 30G, which is a hemming portion, is formed by closely contacting each other. The widthwise dimension of the third flange portion 30G is set to be substantially the same as the widthwise dimension of the second corner end portion 26D of the corner portion 26 of the top portion 28 and the second headrest support end portion 34D of the headrest support portion 34. There is. Therefore, the top portion 28
The second headrest support end portion 34D of the headrest support portion 34 is continuously connected to the second corner end portion 26D of the corner portion 26 as it is, and the second corner end portion 26D of the corner portion 26 is continuously connected as it is. The third flange portion 30G is extended to the connecting portion of the side portion 24 and the general portion 30.

The manufacturing process of the cross-sectional shape of the above construction is shown in FIGS. 14 and 15, but it is basically the same as in the case of the third embodiment described above (see FIGS. 10 and 11). Therefore, the description is omitted. The difference from the case of the third embodiment is that
The point is to provide a hemming part necessary for manufacturing the primary processed product.

With the above structure, the same effect as that of the third embodiment can be obtained. Furthermore, according to this embodiment,
Even if the cross section of the top portion 28 has a small diameter, there is an advantage that the moldability is good. That is, in the third embodiment, as shown in FIG.
In the step shown in (C), the second corner end 26
Since C is restricted when entering the inclined recess 78,
If the cross section of the top portion 28 has a small diameter, molding becomes difficult, but according to the present embodiment, such a problem does not occur because hemming is performed in advance.

In the first embodiment, the gradually changing flange portion 30D is provided only at the connecting portion, but the present invention is not limited to this, and the gradually changing flange portion 30D is provided from the connecting portion to the lower end portion of the general portion 30. Good. On the contrary, in the second to fourth embodiments, the second flange portion 30E, the entire general portion 30 including the connecting portion,
Although the third flange portion 30F is provided, these may be provided at least in the connecting portion.

[0059]

As described above, in the vehicle seat back frame structure according to the present invention as set forth in claim 1, at least the connecting portion that transitions from the side portion having the open cross section to the corner portion of the top portion having the closed cross section. In addition, since a gradual change flange portion is provided that extends inward from the pair of flange portions in the cross section, is connected to the pair of corner ends, and has an extension length that gradually changes, a relatively large load to the rear of the vehicle Even when it is added to the top portion, it has an excellent effect that it is possible to suppress the stress concentration from occurring in the connection portion between the left and right side portions and the top portion as much as possible.

Further, in the vehicle seat back frame structure according to the present invention as defined in claim 2, at least a pair of first and second connecting portions are provided at the joint portion that transitions from the side portion having the open cross section to the corner portion of the top portion having the closed cross section. The first flange portion is bent from the first flange portion to the base portion side, and the bending width is substantially the same as the width of the pair of first corner end portions.
Since a pair of second flanges that are connected to the corner ends are provided, even when a comparatively large load to the rear of the vehicle is applied to the top part, stress is concentrated on the connection part between the left and right side parts and the top part. It has an excellent effect that the occurrence of the above can be suppressed as compared with the present invention described in claim 1.

Further, the vehicle seat back frame structure according to the present invention according to claim 3 is the vehicle seat back frame structure according to claim 2, further comprising a pair of first corner end portions to a corner base portion at the corner portion of the top portion. The second corner ends bent respectively to the sides are provided, and at the side parts,
It is bent from the pair of second flange portions to the pair of side portions or the pair of first flange portions, respectively, and the bending width is substantially the same as the width of the second corner end portion, and at the pair of second corner end portions. Since the third flange portion to be connected is provided, in addition to the effect achieved by the present invention as set forth in claim 2, a seatback frame having a simple structure and a high-strength seat does not cause an increase in the size of the seatback frame and a complicated manufacturing method. It has an excellent effect that a back frame can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a seat back frame according to a first embodiment.

FIG. 2 is an enlarged perspective view showing a connecting portion between a side portion and a top portion in the seat back frame shown in FIG.

3 is a cross-sectional view showing a cross-sectional structure of each part of the seat back frame shown in FIG. 1, where (A) is 3 (A) in FIG.
-3 (A) line sectional view, (B) is 3 (B)-of FIG.
3 (B) is a sectional view taken along the line 3 (B), and FIG.
It is a (C) line sectional view.

4 is an overall perspective view showing a front seat provided with the seat back frame shown in FIG. 1. FIG.

5A to 5C are process drawings for explaining a manufacturing process of the seat back frame shown in FIG.

FIG. 6 is a perspective view of a connecting portion corresponding to FIG. 2 showing a structure of a seat back frame according to a second embodiment.

7 is a sectional view corresponding to FIG. 3 showing a sectional structure of each part of the seat back frame shown in FIG. 6.

FIG. 8 is a perspective view of a connecting portion corresponding to FIG. 6 showing a structure of a seat back frame according to a third embodiment.

9 is a sectional view corresponding to FIG. 7, showing a sectional structure of each part of the seat back frame shown in FIG.

FIG. 10 is a process drawing for explaining the procedure for manufacturing the corner portion of the top portion of the third embodiment.

FIG. 11 is a process drawing for explaining the procedure for manufacturing the general portion of the side portion of the third embodiment.

FIG. 12 is a perspective view of a connecting portion corresponding to FIG. 8 showing a structure of a seat back frame according to a fourth example.

13 is a cross-sectional view corresponding to FIG. 9 showing a cross-sectional structure of each part of the seat back frame shown in FIG.

FIG. 14 is a process drawing for explaining the procedure of manufacturing the corner portion of the top portion of the fourth embodiment.

FIG. 15 is a process drawing for explaining the procedure for manufacturing the general portion of the side portion of the fourth embodiment.

FIG. 16 is a perspective view showing a conventional seat back frame structure.

FIG. 17 is a sectional view showing a sectional structure of each part of the upper seat back frame shown in FIG. 16;

FIG. 18 is a process drawing for explaining the manufacturing process for the upper seat back frame shown in FIG. 16.

[Explanation of symbols]

 14 seat back 18 seat back frame 24 side portion 26 corner portion 26A corner base portion 26B (first) corner end portion 26C second corner end portion 28 top portion 30A base portion 30B side portion 30C (first) flange portion 30D gradually changing flange Part [claim 1] 30E second flange part [claim 2] 30F third flange part [claim 3] 30G third flange part [claim 3]

Claims (3)

[Claims] 1. A pair of wide side portions arranged in both side portions of the seat back in the width direction and extending in the seat back height direction, and a corner disposed in the upper end portion of the seat back along the width direction of the seat back. A seat back frame structure for a vehicle, which includes a top portion connected to a pair of side portions via a portion, and is formed in a substantially inverted U shape as a whole, the side portion being a general surface of the side portion. And a pair of side portions that are bent from both sides of the base portion to the inside of the seat back, and a pair of flange portions that are bent substantially parallel from the end portions of each side portion to the center side of the base portion. And a substantially U-shaped open cross-section including, and the corner portion of the top portion has a substantially C-shaped cross-section corner base and both ends of the corner base toward the center side of the corner base. A substantially circular closed cross section including a pair of corner ends that are bent and abutted against each other, and further, at least a corner portion from the side portion that is the open cross section to the top portion that is the closed cross section. In the connecting portion that transitions to, a gradually changing flange portion that extends inward from the pair of flange portions in the cross section and is connected to the pair of corner end portions and that has an extension length that gradually changes is provided. The vehicle seat back frame structure. 2. A pair of wide side portions arranged in both side portions of the seat back in the width direction and extending in the seat back height direction, and arranged in the upper end portion of the seat back along the width direction of the seat back and corners. A seat back frame structure for a vehicle, which includes a top portion connected to a pair of side portions via a portion, and is formed in a substantially inverted U shape as a whole, the side portion being a general surface of the side portion. And a pair of side portions that are bent from both sides of the base portion toward the inside of the seat back, and a pair of first portions that are bent substantially in parallel from the end portions of each side portion toward the center of the base portion. It is configured with a substantially U-shaped open cross section including a flange portion, and the corner portion of the top portion is a corner base portion having a substantially C-shaped cross section and both ends of the corner base portion are closer to the center side of the corner base portion. A substantially circular closed cross-section including a pair of first corner ends bent and abutted against each other, and further, at least from a side part that is the open cross-section to a top part that is the closed cross-section. Of the pair of first flange portions to the base portion side, and the bending width is substantially the same as the width of the pair of first corner end portions, and First
A vehicle seat back frame structure, comprising a pair of second flange portions connected to corner ends. 3. Further, the corner portion of the top portion is provided with second corner end portions that are respectively bent from the pair of first corner end portions toward the corner base portion side, and the side portion includes the pair of second corner end portions. The second flange portion is bent to the pair of side portions or the pair of first flange portions, respectively, and the bending width is substantially the same as the width of the second corner end portion, and the pair of second corner end portions. The vehicle seat back frame structure according to claim 2, further comprising a third flange portion connected to the.