JPH0479911A - Plastic sheet frame and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent occurrence of weld, though long fiber advantageous in strength is contained, by forming to a desired form by stamping a blank material comprising a fiber reinforced plastic. CONSTITUTION:A sheet frame 1 is formed integrally by stamping. The stamping formation is made by pressing a heated long fiber blank material 12a and heated short fiber blank materials 12b, 12c with molds 10, 11. The respective blank materials 12a, 12b, 12c are planar fiber reinforced plastics and are cut to sizes similar to the size of a bottom plate portion 2. The long fiber blank material 12a contains long fiber 16 in the thermoplastic matrix resin 15. The short fiber blank materials 12b, 12c contain short fiber 17 in the matrix resin 15. Therefore, by at least the short fiber 17 flowing in, the resin 15 is reinforced so that the occurrence of the disadvantage in strength is evaded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic seat frame suitable for a seat for a vehicle such as an automobile, and a method for manufacturing the same.

[Prior Art] Vehicle seats are desired to be lightweight and have high strength. Seat frames made of fiber-reinforced plastic (FRP) have the advantages of being lighter than steel ones, requiring fewer parts, being relatively easy to mold, and meeting the required strength, making them ideal for vehicle seat frames. Suitable for materials such as Fiber-reinforced plastics used for such applications have better strength when the fibers contained in the matrix resin are longer, so in products where strength is important, such as seat frames, long fibers are used. There is a tendency to use

When molding a seat frame using fiber-reinforced plastic, stamping molding is suitable.

For stamping molding, a blank material (hot blank) made of thermoplastic matrix resin containing fibers is used. This blank material is heated to a temperature higher than the softening temperature of the matrix resin, set in a mold whose temperature is controlled to a predetermined temperature, and then the mold is clamped to allow the matrix resin and fibers to flow into the cavities within the mold. A molded product having a desired shape can be obtained.

[Problems to be Solved by the Invention] The seat frame generally has a tray shape, and as shown in FIG. 6, a flange-shaped end portion is formed on the upper edge of the rising wall a as an end treatment. That's what I do.

However, this flange-like end portion is troublesome when performing stamping molding. That is, during stamping molding, a portion consisting only of fat may be locally formed.

Welds tend to occur not only at flange-like ends but also at locations where resin flow intertwines, or where resin flows last. The areas where welds are formed are not substantially reinforced by fibers, and therefore are weak points in terms of strength, such as becoming starting points for small cracks.

Furthermore, in the past, since a homogeneous blank material was used throughout the frame, it was difficult to mold the frame so that it would have a reasonable distribution of strength in accordance with the required strength of each part of the frame.

Therefore, an object of the present invention is to provide a plastic sheet frame that can suppress the occurrence of welding even though it does not contain long fibers that are advantageous in terms of strength, and that can also adjust the strength distribution according to the required strength of each part of the molded product. and its manufacturing method.

[Means for Solving the Problems] The plastic seat frame of the present invention developed to achieve the above object is one in which a blank material made of fiber-reinforced plastic is molded into a desired shape by stamping molding. It is characterized in that a long fiber resin layer containing long fibers in the matrix resin and a short fiber resin layer containing short fibers in the matrix resin are polymerized in the thickness direction and integrated. The length of the above-mentioned fibers may include not only long and short lengths but also intermediate lengths.

Further, the method of the present invention, when molding a blank material into a desired frame shape by stamping molding, uses a long fiber blank material containing long fibers in a thermoplastic matrix resin, and a long fiber blank material containing long fibers in the matrix resin. The resin layer containing the long fibers and the resin layer containing the short fibers are integrated with each other by stacking the short fiber blank material containing the short fibers in the thickness direction and performing stamping molding.

Note that the number of blanks and the stacking order are arbitrary. Furthermore, the size, shape, and overlapping position of the blank materials can be arbitrarily selected.

[Function] The seat frame of the present invention is stamped by selecting the polymerization state of the long fiber blank material and the short fiber blank material depending on the strength required for each part of the frame. For example, the blank material is distributed so that a large proportion of long fibers are used in areas where impact resistance is required.

During stamping molding, the highly fluid short fibers contained in the short fiber blank material flow into the edges and corners of the molded product together with the matrix resin.
Welds are prevented even in areas where long fibers are difficult to flow into. It is also possible to produce short fibers on the surface by changing the method of setting the blank material. This can be adjusted depending on the part of the molded product.

[Example 1] An example of this invention will be described below with reference to Figures 1 to 3.
This will be explained with reference to the figures.

The plastic seat frame 1 for an automobile shown in FIG. 1 has a tray shape and includes a bottom plate part 2 and a rising wall 3 provided around the entire circumference of the bottom plate part 2. The rising wall 3 is integrally formed with the bottom plate part 2, and a flange-shaped end 4 facing outward is provided on the upper edge of the rising wall 3 over the entire circumference. Bolt insertion holes 5 are provided at appropriate positions in the bottom plate portion 2 to be used for fixing to a legal member such as a seat slide mechanism (not shown). Near the rear of the rising wall 3, a bolt insertion hole 6 is provided for use in attaching a bracket such as a reclining mechanism or a hinge mechanism (not shown).

The seat frame 1 is integrally molded into the above shape by stamping molding. The stamping molding is performed using upper and lower molds 10° and 11 as illustrated in FIG. 3, and a heated long fiber blank material 12a and a heated short fiber blank material 12b are used.

This is done by pressing 12c with the mold 10.11.

Each of the blank materials 12a, 12b, and 12c is made of flat fiber-reinforced plastic, and is cut to the same size as the bottom plate portion 2. The long fiber blank material 12a is
The thermoplastic matrix resin 15 contains long fibers 16. The short fiber blank materials 12b and 12C are those in which the above matrix resin 15 contains short fibers 17.

An example of the matrix resin 15 is polypropylene, but other than that, polyethylene and other thermoplastic resins can also be used. The long fibers 16 and short fibers 17 are
In each case, an example of the fiber diameter is glass fiber of around 20 μm. The fiber content depends on the mechanical properties required of the seat frame 1, but is usually several tens of percent or more.

The length of the long fibers 16 is preferably 100 to 18
0 ms, more preferably 120 layers to 130 layers.

The recommended length of short fiber 17 is between 8 liters and 60 liters.
More preferably, the position is 13■@yabui. fiber 1
Glass is recommended as the material for 116.17 in terms of cost, but carbon fiber or organic fiber with high tensile strength may also be used if cost permits.

When performing stamping molding using the blank materials 12a, 12b, and 12c, the molds 10 and 11 are heated to a predetermined temperature (
In this example, the temperature is controlled to below 100°C, and
Blank materials 12a, 12b.

12c is heated in an oven to a temperature higher than the softening temperature of the matrix resin 15 (for example, around 210° C.). Blank materials 12a, 12b, 12 taken out from the oven
c is placed on mold 11 and pressurized between molds 10 and 11. By this mold clamping, matrix resin 15 and fibers 16.1
7 flows in the cavity 20 between the molds 10 and 11, forming the bottom plate part 2, and the resin 15 and fibers 16 and 17 also flow into the rising wall 3, thereby forming it into a predetermined frame shape. .

As mentioned above, the number of long fibers 16 is 100IIl11 or more, and since they are randomly mixed into the resin 15, they are intertwined with each other. Therefore, the long fibers 16 are
The higher the fiber content, the worse the fluidity, and the harder it is to flow into the flange-shaped end 4 during stamping. On the other hand, since the short fibers 17 are only about one-tenth as long as the long fibers 16, they are mixed into the resin 15 in a fluidized state.

Therefore, the short fibers 17 are made of resin 15 during stamping molding.
Since a sufficient amount also flows into the end portion 4 etc.,
As schematically shown in FIG.
5 and hardens. Therefore, even in places where the long fibers 16 cannot sufficiently flow, the resin 15 is strengthened by at least the short fibers 17 flowing in, so welds of only the resin 15 do not occur, and weak points in strength occur. is avoided.

Schematically speaking, as shown in FIG. 2, the seat frame 1 of this embodiment formed by the above-mentioned stamping molding has a long fiber resin layer 21 containing only long fibers 16 in the middle part in the thickness direction. , short fiber resin layers 22 and 23 containing only the short fibers 17 overlap on both sides of the long fiber resin layer 21 in the thickness direction. However, in reality, the matrix resin 15 of the resin layers 21, 22, and 23 is integrated with each other by stamping molding, and the resin layers 21, 22, and 23 are completely integrated. In the case of such a sandwich structure, the lengths of the fibers 17 may be made different between the short fiber resin layer 22 on one side and the short fiber resin layer 23 on the other side.

Further, depending on the magnitude of the strength load acting on the seat frame 1, the long fiber blank material 12a and the short fiber blank material 12
Adjust the polymerization state of b and 12c.

For example, since it is advantageous to be reinforced with long fibers 16 in terms of impact strength, a large amount of long fiber blank material 12a is used in areas where impact strength is required so that a large amount of long fibers 16 is used. That's how it goes.

Note that, as shown in FIG. 4, a resin layer 22 containing short fibers 17 may be provided on one side in the thickness direction of the resin layer 21 containing long fibers 16. In this case, as shown in FIG. 5, a long fiber blank material 12a and a short fiber blank material 12b similar to those described above are superposed on a mold 11, and stamping molding is performed.

[Effects of the Invention] According to the present invention, even in places where long fibers are difficult to flow into, such as the edges of stamped products, short fibers flow in and strengthen the resin, so long fibers with excellent strength can be used. Even though it contains, the occurrence of welds is avoided.

Therefore, weak points in strength caused by welding can be overcome, and stable molded product strength can be obtained.

Further, according to the method of the present invention, a plastic sheet frame with a rational strength distribution can be obtained by adjusting the usage conditions of the long fiber blank material and the short fiber blank material according to the required strength of each part of the molded product.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a plastic sheet frame showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a schematic diagram of a mold used for stamping molding. FIG. 4 is a cross-sectional view schematically showing a modified example of the resin layer, FIG. 5 is a cross-sectional view showing the blank material polymerization state when obtaining the resin layer shown in FIG. 4, and FIG. The figure is a sectional view showing a part of a conventional plastic seat frame. DESCRIPTION OF SYMBOLS 1... Plastic sheet frame, 2... Bottom plate part, 3... Standing wall, 4... End of molded product, 10 degrees 11... Mold, 12a... Long fiber blank material, 12b
12c... Short fiber blank material, 15... Matrix resin, 16... Long fiber, 17... Short fiber, 21.
... Long fiber resin layer, 22.23... Short fiber resin layer.

Claims (2)

[Claims] (1) A plastic sheet frame formed into a desired frame shape by stamping a blank material made of fiber-reinforced plastic, comprising a long fiber resin layer containing long fibers in a matrix resin, and a matrix resin layer containing long fibers. A plastic seat frame characterized in that a short fiber resin layer containing short fibers in the resin is polymerized and integrated in the thickness direction. (2) When molding a blank material into a desired frame shape by stamping molding, a long fiber blank material containing long fibers in a thermoplastic matrix resin and a long fiber blank material containing short fibers in the matrix resin are used. A method for manufacturing a plastic seat frame, characterized in that a resin layer containing long fibers and a resin layer containing short fibers are integrated with each other by stacking a short fiber blank material in the thickness direction and stamping molding.