JP2971536B2 - Plastic seat frame - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plastic seat frame suitable for a vehicle seat such as an automobile.

[Related Art] It is desired that a vehicle seat be lightweight and have high strength. Seat frames made of fiber reinforced plastic (FPR) have the advantages of being lightweight, requiring fewer parts, being relatively easy to mold and satisfying the required strength, compared to steel, and are suitable for vehicle seat frames. Suitable for materials. Fiber reinforced plastics used in such applications have longer fibers in the matrix resin because they are superior in strength. Tend to use.

When molding a seat frame using fiber reinforced plastic, stamping molding is suitable. In stamping molding, a blank material (hot blank) in which fibers are contained in a thermoplastic matrix resin is used. This blank material is heated above the softening temperature of the matrix resin, set in a mold whose temperature has been adjusted to a predetermined temperature, and then clamped. Thus, a molded product having a desired shape is obtained.

[Problem to be Solved by the Invention] The seat frame generally has a tray shape.
As shown in the drawing, a flange-shaped end b is formed at the upper edge of the rising wall a as a terminal treatment. However, this flange-shaped end b is troublesome when performing stamping molding. That is, at the time of stamping molding, the long fiber c cannot sufficiently flow into the end portion b, and a so-called weld-resin-rich portion substantially consisting of only the resin is locally caused. The weld has a flanged end b
In addition to the above, it is also likely to occur at places where the resin flow is entangled or where the resin flows last. Since the weld is not substantially reinforced by fiber,
It is a weak point, such as a starting point for the occurrence of small cracks.

Accordingly, an object of the present invention is to provide a plastic sheet frame that contains long fibers that are advantageous in strength but does not cause welds.

Means for Solving the Problems The present invention developed to achieve the above object provides a plastic sheet frame formed into a desired frame shape by stamping and molding a blank material.
The blank material is made of a fiber reinforced plastic, and the fiber reinforced plastic is made of a long fiber resin layer containing a long fiber having a length of 100 to 160 mm in a thermoplastic matrix resin and a short fiber having a length of 8 to 60 mm in a matrix resin. It is characterized by comprising a short fiber resin layer containing fibers and laminated so as to be located on the outer surface side in the thickness direction of the blank material.

[Operation] The seat frame of the present invention is used for stamping molding.
Short fibers with excellent fluidity contained in the blank material,
Since it flows into the end or corner of the molded article together with the matrix resin, the occurrence of weld can be prevented even at a location where the long fiber does not easily flow.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The automotive plastic seat frame 1 shown in FIG. 1 has a tray shape, and is provided with a bottom plate portion 2 and a rising wall 3 provided over the entire circumference of the bottom plate portion 2. The rising wall 3 is formed integrally with the bottom plate portion 2, and furthermore, the upper edge of the rising wall 3 is provided with a flange-like end 4 facing outward over the entire circumference. At an appropriate position of the bottom plate portion 2, a bolt insertion hole 5 used for fixing to a floor-side member such as a seat slide mechanism (not shown) is provided. Near the rear of the rising wall 3,
A bolt insertion hole 6 used for mounting a bracket such as a reclining mechanism or a hinge mechanism (not shown) is provided.

The seat frame 1 is integrally formed into the above shape by stamping. Stamping molding is the third
This is performed by using the upper and lower dies 10, 11 as illustrated in the figure, and pressing the heated blank material 12 with the dies 10, 11.

The blank material 12 is obtained by cutting a flat fiber-reinforced plastic into the same size as that of the bottom plate portion 2, and as shown in FIG. However, in order to more effectively suppress the occurrence of weld, a long fiber resin layer 21 containing long fibers 16 and a short fiber 17 are contained as shown in FIG. In addition, a laminate structure including the short fiber resin layer 22 laminated on the outer surface side of the blank material 12 is desirable. The matrix resin 15 is integrated with each of the resin layers 21 and 22 before or after the stamping molding, and is completely integrated. An example of the matrix resin 15 is polypropylene, but in addition,
Polyethylene and other thermoplastic resins can be applied. Each of the long fiber 16 and the short fiber 17 is a glass fiber having an example of a fiber diameter of about 20 μm. The fiber content depends on the mechanical properties required for the seat frame 1, but is usually several tens% or more.

The length of the long fiber 16 is preferably 100 mm to 160 mm, more preferably 120 mm to 130 mm. The recommended length of the short fiber 17 is 8 mm to 60 mm, more preferably 13 mm
Good place. Glass is recommended for the material of the fibers 16 and 17 in terms of cost, but carbon fibers and organic fibers having high tensile strength may be used if cost is acceptable.

When performing stamping molding using the blank material 12, the molds 10 and 11 are heated to a predetermined temperature (100 ° C. or less in this embodiment).
The blank material 12 is heated in an oven at or above the softening temperature of the matrix resin 15 (for example, 210 ° C.).
Heat before and after). The thickness of the blank material 12 before heating is, for example, about 3 mm to 5 mm, but after heating, the fibers 16, 1
Due to the springback effect of 7, the thickness is increased and the state is expanded. Mold blank material 12 removed from oven
Place on 11 and press between molds 10,11. By this mold clamping, the matrix resin 15 and the fibers 16 and 17 flow in the cavity 20 between the molds 10 and 11, and the bottom plate portion 2 is formed. By flowing, it is formed into a predetermined frame shape.

As described above, the long fiber 16 is 100 mm or more, and the resin 15
Since they are mixed randomly, they are intertwined with each other. Therefore, the higher the fiber content, the worse the flowability of the long fiber 16 becomes, and it is difficult for the long fiber 16 to flow into the flange-shaped end 4 during stamping. On the other hand, the short fiber 17 is only about one tenth the length of the long fiber 16, and is therefore mixed in the resin 15 in a state where it can easily flow. For this reason, the short fiber 17 is formed at the end 4 together with the resin 15 during stamping molding.
Since a sufficient amount flows into the resin 15 and the like, the resin is mixed with the resin 15 at the end 4 and hardened, as schematically shown in FIG. Therefore, even in a place where the long fibers 16 cannot sufficiently flow, the resin 15 is reinforced by at least the short fibers 17 flowing, so that welding of only the resin 15 does not occur, and a strength weak point is generated. Is avoided.

As shown in FIG. 6, the blank material 12 has resin layers 22 and 23 containing only short fibers 17 on both sides in the thickness direction (upper and lower surfaces in the drawing) of a resin layer 21 containing only long fibers 16. May be present. Also in this case, the short fiber resin layers 22 and 23 are laminated on the outer surface side of the blank material 12, which is effective in suppressing the occurrence of weld. In the case of such a sandwich shape, the length of the fiber 17 may be different between the one short fiber resin layer 22 and the other short fiber resin layer 23.

Further, the long fibers 16 and the short fibers 17 may be mixed at an optimum ratio according to the magnitude of the strength load acting on the seat frame 1. For example, since it is more advantageous for the impact strength to be reinforced by the long fibers 16, measures to increase the content of the long fibers 16 may be taken in a portion where impact strength is required.

[Effects of the Invention] According to the present invention, even in a place where long fibers do not easily flow in, such as an end portion of a stamping molded product, short fibers flow to reinforce the resin. Although it contains, the occurrence of weld is avoided,
The ends of the frame and the like are reinforced by the short fibers. This overcomes the strength weakness caused by the weld,
Stable molded product strength is obtained. In addition, since the occurrence of welds can be suppressed even in a relatively complicated shape, it is suitable for a stamping molded product having a complicated shape.

[Brief description of the drawings]

FIG. 1 is a perspective view of a plastic sheet frame showing one embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 shows an outline of a mold used for stamping molding. FIG. 4 is a cross-sectional view schematically showing a part of the blank material used for the plastic sheet frame shown in FIG. 1, and FIGS. 5 and 6 each show a different modification of the blank material. FIG. 7 is a sectional view schematically showing a part of a conventional plastic sheet frame. 1 ... Plastic sheet frame, 2 ... Bottom plate part, 3
…… Rising wall, 4 …… End of molded product, 10,11 …… Mold, 1
2 ... blank material, 15 ... matrix resin, 16 ... long fiber, 17 ... short fiber.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI B29K 105: 12 (58) Investigated field (Int.Cl. ⁶ , DB name) A47C 7/16 B29C 51/12 B32B 27/04 B29C 43 / 02 C08L 101/00

Claims (1)

(57) [Claims] 1. A plastic sheet frame formed into a desired frame shape by stamping a blank material, wherein the blank material is made of fiber reinforced plastic, and the fiber reinforced plastic is
A long fiber resin layer containing a long fiber of 100 to 160 mm in a thermoplastic matrix resin, and a length of 8 mm in the matrix resin.
A plastic sheet frame comprising a short fiber resin layer containing short fibers of up to 60 mm and laminated so as to be located on the outer surface side in the thickness direction of the blank material.