JPH047893B2 - - Google Patents

Description

Detailed Description of the Invention Industrial Field of Application The present invention is directed to molding a hollow body in which a plurality of tubular parts communicating with the hollow body are provided around the hollow body in a direction in which the axes intersect with each other. This invention relates to a method for blow molding a hollow body.

BACKGROUND ART FIG. 5 shows a lumbar support for an automobile part, which is an example of the above-mentioned hollow body, and this lumbar support a has a plurality of tubular parts b, b, ... are provided in substantially the same plane and protrude in directions perpendicular to each other. Since a pipe joint is inserted into the inner surface of each tubular portion b of this lumbar support a, it must be a smooth cylinder with precision.

Conventionally, this type of hollow body has been molded by blow molding.

Problems to be Solved by the Invention When a hollow body in which a tubular part communicating with the hollow part protrudes around the periphery is formed by a normal blow molding method, grooves peculiar to blow molding are formed on the inner peripheral surface of each tubular part. However, as described above, this groove causes air leakage when a pipe joint is inserted into the tubular part and communicates with the hollow part.

In order to prevent the formation of this groove, it is possible to insert a core that regulates the inner diameter of the tubular part in advance and clamp it during mold clamping. It would have been impossible to break through with the core.

Therefore, a molding method has been used in which two sheets are used and the core is placed between the sheets to mold a tubular part with a regulated inner diameter. Unlike the parison molding method, since the pressure between the sheets is the same as atmospheric pressure, there was a problem that the sheets came into contact with each other and welded together when the mold was clamped, making it impossible to mold the hollow part.

Means and Effects for Solving the Problems The present invention has been made in view of the above-mentioned problems, and includes a side wall cavity for forming each left and right side of a hollow body, and a tubular section cavity for forming a tubular section. Between the left and right split molds, there is an intermediate mold that has a core that surrounds the outside of the split mold and that regulates the inner diameter of the tubular part in accordance with the cavity for the tubular part of the split mold. , place two molten sheets between the left and right split molds and the intermediate mold, and then apply each molten sheet to the left and right end surfaces of the intermediate mold in an airtight manner using a sliding mold. After that, the left and right split molds were moved forward and clamped to form a hollow body inside the intermediate mold.

Example Embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a molding apparatus for carrying out the present invention, in which 1 and 2 are left and right split molds,
Cavities for molding the lumbar support a, that is, a side cavity 3 and a tubular cavity 4 protruding to the periphery, are respectively formed on opposing surfaces of the split molds 1 and 2. Reference numerals 5 and 6 denote sliding molds formed in a frame shape so as to surround the outside of the tip of each of the divided molds 1 and 2, and these sliding molds 5 and 6 are used for each of the divided molds 1 and 2. It is provided so as to be slidable in the backward direction from a position flush with or slightly protruding from the tip of the tip, and biased by a spring 7 in the tip direction. The opposing end surfaces of both sliding molds 5 and 6 are parallel to each other.

Reference numeral 8 denotes an intermediate mold located between the two split molds 1 and 2, and this intermediate mold 8 is formed into a frame shape having the same end face shape as the two sliding molds 5 and 6. It has a predetermined thickness in the moving direction of the split molds 1 and 2. This intermediate mold 8 is held by a holding device (not shown). Inside this intermediate mold 8 is a core 9 that regulates the inner diameter of the tubular part of the molded product.
is set up so that you can come and go as you like. This core 9 is provided at a position corresponding to the tubular cavity 4 of the split molds 1 and 2, and its length when projected is long enough to reach the side cavity 3. 10 is a cylinder that operates this core 9.

The forming operation using the forming apparatus having the above structure will be explained below with reference to FIGS. 2 to 4.

(1) Two molten sheets 11 and 12 are suspended on both sides of the intermediate mold 8 with the two split molds 1 and 2 separated. At this time, each core 9 is made to protrude into the intermediate mold 8 (FIG. 2).

(2) Start mold clamping. During mold clamping, the molten sheets 11 and 12 are first clamped between the sliding molds 5 and 6 and both end surfaces of the intermediate mold 8 (FIG. 3). In this state, the interiors of both sheets 11 and 12 are sealed within the intermediate mold 8.

(3) Furthermore, the split molds 1 and 2 are clamped to the end (Fig. 4). In this state, both sheets 11 and 12 are expanded and molded into a shape along each cavity 3 and 4 of both split molds 1 and 2 by internal pressure. Further, a core 9 is positioned at the inner diameter portion of each tubular portion to regulate the inner diameter thereof. Note that the sheets 11 and 12 at the outer periphery of the split molds 1 and 2 are maintained in a state where they are clamped to the respective sliding molds 5 and 6 and the intermediate mold 8.

(4) After maintaining the mold clamped state for a predetermined time, the mold is opened and the core 9 is inserted into the intermediate mold 8 from the inside, thereby forming the lumbar support shown in FIG. 5.

In addition, if the internal pressure in both sheets 11 and 12 increases too much during mold clamping, it is also possible to form a hole in the core 9 that communicates with the outside and release the internal pressure to the outside through a pressure regulating valve. The appropriate internal pressure during molding is 2 to 5 atmospheres.

FIG. 6 shows another example of the molding device, in which the sliding molds 5 and 6 are biased by an air cylinder 13 instead of a spring.
An example is shown below.

Further, in the embodiment shown in FIGS. 1 to 4, the space inside the intermediate mold 8 is sealed, and the air in this space is compressed by the clamping of the split molds 1 and 2, and the pressure is applied to the sheet 11. , 12 have been shown to be expansion molded, but in addition to the above-mentioned internal pressure, pressure fluid may be blown into the hollow space from a fluid blowing passage 14 provided in the core 9, as shown in FIG. In FIG. 6, 15 is a degassing hole.

The lumbar support shown above as an example of the hollow body of the present invention improves riding comfort by changing the degree of elasticity using air pressure, and is therefore made of an elastic body such as rubber or elastomer. However, the material of the hollow body of the present invention is not limited to these elastic bodies; for example, it can also be formed of a non-elastic body, such as a container for multicolored liquids having a mixing function inside.

Effects of the Invention According to the present invention, the following effects can be achieved.

(1) Since the inner diameter is regulated by the core 9, a tubular portion with uniform wall thickness can be obtained.

(2) Since the core 9 is always positioned at the center of the mold using the intermediate mold 8 as a guide, the thickness of the tubular portion does not vary.

(3) Since two sheets are used for molding, it is possible to mold a hollow body around the molded body with tubular portions protruding in directions intersecting the axes of each other.

(4) Since the two sheets 11 and 12 are separated by the intermediate mold 8 and the pressure between the sheets 11 and 12 is higher than atmospheric pressure, both sheets 11 and 12 are It is possible to prevent mutual contact and welding.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a molding device used in the method of the present invention, Figs. 2 to 4 are explanatory diagrams of the operation, and Fig. 5 shows a lumbar support which is an example of a molded article formed by the method of the present invention. The perspective view shown in FIG. 6 is a sectional view showing the main parts of another example of the molding apparatus. 1 and 2 are split molds, 3 is a side cavity,
4 is a cavity for the tubular part, 5 and 6 are sliding molds, 8
9 is an intermediate mold, 9 is a core, and 11 and 12 are molten sheets.

Claims (1)

[Claims] 1. In a blow molding method for a hollow body in which a plurality of tubular parts communicating with the hollow interior are provided on the outer periphery of the hollow body in a direction in which their axes intersect with each other, side parts for molding the left and right sides of the hollow body. This split mold 1, 2 is placed between the left and right split molds 1, 2 having cavities 3, 3 and cavities 4, 4 for the tubular part for molding the tubular part.
The split mold 1 has a shape that surrounds the outside of the split mold 1,
An intermediate mold 8 having a core 9 inside that regulates the inner diameter of the tubular part is arranged corresponding to the cavities 4, 4 for the tubular part 2, and the left and right split molds 1, 2 and the intermediate mold 8
Two molten sheets 11 and 12 are placed between each of the molten sheets 11 and 12, and then each of the molten sheets 11 and 12 is airtightly clamped to each of the left and right end surfaces of the intermediate mold 8 by the sliding molds 5 and 6. The hollow molding method is characterized in that the left and right split molds 1 and 2 are then moved forward and clamped to form a hollow body inside the intermediate mold 8.