JPH0365322A - Blow molding method for of frame member - Google Patents

Abstract

PURPOSE:To mold a frame member excellent in strength and rigidity relatively inexpensively by molding a plurality of parisons in parallel between a pair of molds by extrusion molding and, after clamping the molds, injecting compressed air in the respective parisons and expanding the parisons in the molding cavity to mutually weld the wall parts of the adjacent parisons. CONSTITUTION:The synthetic resin material 7 in a receiving chamber 8 is pressurized to form five parisons 3 in parallel between molds 20 by extrusion molding and an air supply nozzle 21 is inserted in respective expansion spaces 18 from below and the molds 20 are clamped to grasp the respective parisons 3 in the vicinity of both upper and lower ends thereof by both upper and lower end parts of the molds 20 to bring the expansion spaces 18 to an almost airtight state. Compressed air is injected from the air supply nozzle 21 to expand the respective parisons 3 in the molding cavity 32 of the molds 20 and the wall parts 3a of the front and rear parts of the respective parisons 3 and the outside wall part 3b of the parison 3A are brought into close contact with the inner wall surface of the molds 20 evenly and the wall parts 3b of the left and right parts of the parisons 3 are selded to the wall parts 3b of the adjacent parisons 3 almost evenly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blow molding method for a hollow synthetic resin frame member.

[Prior art]

In general, the molding method for molding hollow synthetic resin frame members involves extrusion molding a parison made of synthetic resin such as polyethylene or polypropylene, and blow molding by expanding this parison with air within the molding cavity of a mold. Molding methods are known.

Normally, if the above frame members are made only of synthetic resin materials, sufficient strength and rigidity cannot be obtained, so frame members that require relatively high strength and rigidity, such as automobile seat frames, are molded. In some cases, fibers such as glass fiber or talc are mixed into the synthetic resin material to increase the strength and rigidity of the molded frame members.

However, fibers such as glass fiber and talc are relatively expensive and have a higher specific gravity than synthetic resin materials, resulting in a problem that the manufacturing cost of the frame member increases and its weight increases.

Therefore, recently, many blow molding techniques have been proposed in which the synthetic resin frame member is reinforced with a metal reinforcing frame.

For example, in Japanese Patent Application Laid-Open No. 61-134225, a reinforcing metal room is configured to be expandable and retractable with a plurality of divided frames, and is connected to an air supply nozzle within a roughly cylindrical parison made of synthetic resin. After the mold is closed, pressurized air is injected into the bag to inflate the bag, and the parison is expanded through the bag while reinforcing the reinforcing frame. A blow molding technique is described in which a reinforced frame is crimped onto a parison and a reinforcing frame is joined to an inner wall of a synthetic resin type frame member.

In addition, Japanese Utility Model Application Publication No. 62-75916M discloses that a synthetic resin molded substantially cylindrical parison and a substantially rectangular frame-shaped metal reinforcing frame L disposed outside the parison are placed in a molding cavity of a mold. After setting and mold-clamping the gold, pressurized air is injected into the parison to expand the parison, and the parison portion on the outer peripheral edge of the frame member wraps the reinforcing frame, thereby bonding the synthetic resin frame member and the reinforcing frame. Blow molding techniques are described that provide integral bonding.

On the other hand, there is also a blow molding technique in which ribs are integrally formed within a synthetic resin frame member to increase its strength and rigidity.

In the above-mentioned blow molding technology, a slide core that can protrude into the mold cavity is provided in the mold, and the walls of the extruded synthetic resin parison are fused together using the slide core to create multiple spaces within the parison. The parison is expanded by injecting pressurized air into the clamping customer space of the mold, and a rib is formed inside the plate member at the fused portion.

[Problem to be solved by the invention]

In the former blow molding technology of the above-mentioned blow molding technology in which a frame member is reinforced with a reinforcing frame made of metal, the reinforcing frame does not protrude outside the surface of the frame member, so the appearance of the frame member is not impaired. Since the material is not wrapped in the parison, the joint area between the reinforcing frame and the synthetic resin frame is small, and the adhesion between the synthetic resin material such as polyethylene or polypropylene and the metal reinforcing frame is not very good, so the reinforcing frame It was difficult to obtain sufficient bonding strength between the frame member and the frame member.

In addition, the latter blow molding technology can increase the bonding strength between the reinforcing frame and the synthetic resin frame member, but since the viscosity of the parison is usually relatively high and the blowing pressure is relatively low, the reinforcing frame is completely covered by the parison. There are problems in that the frame member is not wrapped up, resulting in poor adhesion, resulting in a decrease in bonding strength, and in addition, depressions are formed in the poor adhesion, impairing the appearance of the frame member.

On the other hand, with the blow molding technology that forms ribs within the frame member, the ribs can significantly increase the strength and rigidity of the frame member, but in order to ensure sufficient strength and rigidity, the entire freneme member must be reinforced with fissures. This increases the manufacturing cost of the loom member, and the structure of the mold becomes complicated due to the slide core and the drive mechanism that drives it. There is a problem with becoming.

An object of the present invention is to provide a method for blow molding a frame member, which allows a frame member having excellent strength and rigidity to be molded at a relatively low cost using a blow molding apparatus having a relatively simple configuration.

[Means to solve the problem]

A blow molding method for a frame member according to the present invention is a blow molding method in which a hollow synthetic resin mold frame member is blown into a bottom shape using a blow molding device, and a plurality of parisons of a synthetic resin mold are placed between a pair of molds. After the mold is closed, pressurized air is injected into each parison to expand the parison within the molding cavity and fuse the walls of adjacent parisons together.

[Effect]

In the blow molding method for a frame member according to the present invention, 1
First, a plurality of synthetic resin parisons are extruded in parallel between a pair of molds, and after the molds are clamped, pressurized air is injected into each parison to expand the parisons within the molding cavity. Since the adjacent parison walls are fused together to form the frame member, multiple rifs are integrally formed inside the flared member by the fused portion, and these ribs increase the strength and rigidity of the frame member. It will be done.

When molding the multiple parisons mentioned above, it is also possible to mix fibers into a given parison, and by reinforcing only the parts of the frame member that require strength and rigidity with fibers, a lightweight frame with excellent strength and rigidity can be created. The parts can also be manufactured relatively inexpensively.

In addition, the configuration of the extrusion device of the blow molding device applied to the above blow molding method is somewhat complicated because it extrudes multiple parisons, but the mold, which is replaced as appropriate depending on the type and size of the molded product, can be replaced with an existing simple configuration. It is advantageous in terms of equipment economics because it can be applied to various equipment.

〔Effect of the invention〕

In the method for blow molding a frame member according to the present invention, as detailed in the above [Operation] section, a plurality of ribs can be formed within the frame member at the fused portions of the parison walls. It is possible to increase the strength and rigidity of the frame member by reinforcing it with multiple ribs, it is advantageous in terms of equipment economy since the existing mold can be used, and it is possible to mix fisi into the specified parison. By doing so, it is possible to obtain effects such as being able to manufacture a frame member that is lightweight and has excellent strength and rigidity at a relatively low cost.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

This example is a case where the present invention is applied to a blow molding method for a seat back frame of a hollow synthetic resin automobile seat.

First, the blow molding apparatus 1 will be explained.

The blow molding device 1 includes an extrusion device 4 that extrudes five parisons 3, and a blow molding section 5 that is disposed below the extrusion device 4 and blow molds the extruded parisons 3.
It is structured as follows.

To explain the extrusion device 4, as shown in FIGS. 1 and 2, the accumulator head 6 is provided with five slide cores 9 at predetermined intervals in the left and right direction, and each slide core 9 is connected to the accumulator head 6. A substantially cylindrical storage chamber 8 capable of accommodating one shot of synthetic resin material 7 is formed on the outside of each slide core 9 in the lower and middle portions of the accumulator head 6, so as to be movable in the vertical direction.
A substantially cylindrical piston member 10 capable of pressurizing the inside of the storage chamber 8 is movably attached to the upper half of each slide core 9, and the lower and middle portions of the piston member 10 are attached to the accumulator head 6 in an airtight manner. A hydraulic cylinder 11 is provided above the accumulator head 6 to drive each piston member 10 in the vertical direction, and a material supply device ( A material supply cylinder 12 (path shown) is connected.

Of the storage chambers 8, the outer pair of chambers 8 is filled with a synthetic resin material 7A having a high fibrous content, and the inner pair of accommodating chambers 8 is filled with a synthetic resin material 7B having a low fibrous content. The central storage chamber 8 is filled with a synthetic resin material 7C that does not contain fissures.

A generally annular extrusion passage 13 with an open lower end communicating with the storage chamber 8 is formed between each of the slide cores 9 and the lower end of the accumulator head 6, and when the piston member 10 is driven downward by the hydraulic cylinder 11, The synthetic resin material 7 filled in the storage chamber 8 is extruded from the accumulator head 6 through the extrusion passage 13, and as shown in FIGS. 1 and 3,
Five approximately cylindrical parisons 3 having an expansion space 18 extending in the extrusion direction (up and down direction) are extruded in parallel, and the outer pair of parisons 3A of the parisons 3 is made of synthetic resin material 7A. The inner pair of parisons 3B are made of synthetic resin material 7B, and the central parison 3C is made of synthetic wood material 7C. In addition, the thickness of parison 3 is
By moving the slide core 9 in the vertical direction using a lifting cylinder (not shown), the width of the extrusion passage 13 can be varied and adjusted.

The blow molding section 5 has five extruded parisons 3.
As shown in FIGS. 1 and 2, below the accumulator head 6 are a pair of front and rear molds 20 that can hold the upper and lower ends of the extruded parison 3. is arranged between the molds 20, and an air supply device (
Five air supply nozzles 21 are provided which are connected to the (illustrated path) and capable of supplying pressurized air into each expansion space 18, and each air supply nozzle 21 is moved into the vicinity of the lower end of the parison 3 by a lifting device (not shown). It is driven up and down between the moved position of the block 1 and the retracted position where the parison 3 is moved by -1 below.

Next, the blow molding force method of the seat back frame 31 using the blow molding apparatus 1 described in "2" will be explained.

First, the synthetic resin material 7 heated and melted at 200-300°C in the material supply cylinder 12 is filled into the storage chamber 8.
With the mold 20 opened, the hydraulic cylinder 11 is driven to pressurize the synthetic resin material 7 in the storage chamber 8 with the piston member 10, and five parisons 3 are extruded in parallel between the molds 20.

Next, as shown in FIGS. 1 and 3, the air supply nozzle 21 is inserted from below into each expansion space 18, and then, as shown in FIG. 4, the mold 20 is clamped and molded. The upper and lower ends of each parison 3 are held in the vicinity of both upper and lower ends of each parison 3, and the inside of each expansion space 18 is kept substantially airtight.

Next, as shown in FIG. Inflate parison 3. As a result, as shown in FIG. 6, the front and rear walls 3a of each parison 3 and the outer wall 31 of the parison 3A are substantially free from gaps on the inner wall surface of the mold 20 constituting the molding cavity 32. In addition, the left side and right side wall portions 3b of each parison 3 are fused to the wall portions 3b of the adjacent parison 3 with substantially no gap.

Next, the parison 3 is kept in the above state for a predetermined period of time to harden, and then the mold is opened and unnecessary parts are cut out to obtain a sea I back frame 31 shown in FIG.

The seat back frame 31 blow-molded as described above is assembled into each parison 3 as shown in FIGS. 7 and 8.
Due to the fused portion between the wall portions 3b, the front wall portion 3
1a and the rear wall portion 31b are integrally molded from the second end to the lower end,
Seat back frame 31, which requires the most strength and rigidity
Parisons 3A and 3B whose left end and right end contain fisi
Therefore, the seat back frame 31 can be made relatively lightweight by reducing the amount of filler filling, while ensuring sufficient strength and rigidity.

Although the structure of the extrusion device 4 is somewhat complicated, the mold 20, which is frequently replaced depending on the shape of the product, can be an existing simple structure, which is advantageous in terms of equipment economy.

In the above-mentioned blow molding apparatus 1, the height position of the slide core 9 is adjusted so that the parison 3C in the center part becomes thinner, and as shown in FIG. The seat back frame 31A having the thin backrest portion 34 may be blow molded. In this seat back frame 31A, parison 3C
Pressurized air is injected into the space 35 of the backrest portion 34 configured by an on-vehicle factory supply device (not shown) to cause the front wall portion 34a of the backrest portion 34 to protrude toward the passenger side. This also allows the backrest portion 34 to function as a lumbar support.

In addition, one to seven parisons 3 are extruded and a pair of parisons 3 on the outside thereof are made thin, so that the left and right side support parts 36 are made thin as shown in FIG. 1O. may be blow molded. In this seat back frame 31B, pressurized air is injected into the space 37 in the side support part 36 by an on-vehicle air supply device (not shown), and the side support part 36 is inflated according to the size of the occupant to improve ride comfort. - It is possible to improve the horizontal searchability.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a longitudinal sectional view of a blow molding device and an extruded parison, FIG. 2 is a sectional view taken along line nn of FIG. Figure 4 is a diagram equivalent to Figure 3 at the time of mold clamping, Figure 5 is a diagram equivalent to Figure 3 at the time of blow molding, Figure 6 is a diagram equivalent to Figure 3 at the time of completion of blowing, Figure 7 shows the seat pack full
/ -, , /-; FIG. 8 is a sectional view taken along the line nn in FIG. FIG. 8 is a diagram corresponding to FIG. 8, and FIG. 1O is a diagram corresponding to FIG. 8 according to the second modification. 19. Blow forming device, 3, 3A, 3B, 3C, parison, 3b... wall, 20... mold, 31, 31A
・31B... Seat back frame, 32... Molding cavity,

Claims (1)

[Claims] (1) In a blow molding method in which a hollow synthetic resin frame member is blow molded using a blow molding device, a plurality of synthetic resin parisons are extruded in parallel between a pair of molds, and the mold A blow molding method for a frame member, which comprises injecting pressurized air into each parison after mold clamping to expand the parison within a molding cavity and fuse the walls of adjacent parisons together.