JP2002361642A - Method for molding circular pipe with free curvature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for molding a resin by which a circular pipe with a free curvature can easily be obtained at a low cost. SOLUTION: In this method for molding a resin into the circular pipe with a free curvature, a flexible hose 5 incorporating a woven metallic meshwork is built into a cavity 4 of a resin molding die 1 which has an external shape of the circular pipe with a free curvature, formed by a combination of a cavity side part 2 and a movable part 3, then fixed and a molten resin is cast into the molding die. After the resin is cooled and set, the flexible hose 5 is deformed and removed from the molding die and the molding die is opened to remove a cylindrical resin molded product. In addition, a retention pin 6 for retaining the flexible hose 5 is provided in the molding die.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding method for a circular pipe having a free curvature, such as an intake manifold for a vehicle.

[0002]

2. Description of the Related Art When a circular pipe having a free curvature, such as an intake manifold of a vehicle, is manufactured by resin molding,
It is difficult to manufacture easily with the prior art, which leads to an increase in the manufacturing cost of this type of resin molded product. That is, as a conventional technique, there is a method of obtaining a product shape of a resin circular tube by using a slide core incorporated in a molding die and injecting a resin raw material and then pulling out a slide core inside the circular tube. Although it is possible to form a circular tube having a constant curvature, there is a problem that a circular tube having a free curvature cannot be formed.

[0003] As another conventional technique, a lost core molding method is known. This is to manufacture a core (core) that constitutes the inside of the circular tube using a low-temperature molten metal alloy, hold this core in a mold, mold it, and then melt and remove the core, This is a method of obtaining a product shape having a hollow shape. With this method, it is possible to form a circular tube with a free curvature, but it is necessary to manufacture a core for each product,
This leads to a rise in manufacturing costs, and is not suitable for mass production.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a resin molding method capable of easily and inexpensively obtaining a circular tube having a free curvature. It is.

[0005]

According to the present invention, there is provided, as a means for solving the above-mentioned problems, a resin molding method for a circular pipe having a free curvature as described in each of the claims.
The flexible hose according to claim 1, wherein the metal is woven in a mesh shape in a cavity of a resin molding die having an outer shape of the circular tube having a free curvature. After the resin is incorporated and fixed, a molten resin is poured in, cooled and solidified, and then the flexible hose is deformed and pulled out of the resin molding die, thereby forming a cylindrical resin product. This allows
There is no need to melt and remove the core after resin molding as in the prior art, and a circular tube having a free curvature can be easily and inexpensively manufactured by resin molding.

According to a second aspect of the present invention, the flexible hose incorporated in the resin molding die is supported by a holding pin, whereby the flexible hose is formed by the molding pressure during the resin molding. Movement can be prevented, and a product having a stable product shape can be obtained.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a resin molding method for a circular pipe having a free curvature according to an embodiment of the present invention. 1 to 4 show the resin molding method of the present invention in the order of steps. FIG. 1 shows the resin molding die 1 in a state where the fixed die 2 and the movable die 3 shown in FIG. 4 are closed. A cavity 4 having an outer shape of a circular tube having a free curvature is formed in the closed mold 1, and a flexible hose 5 is incorporated in the cavity 4.
Both ends are fixed between the fixed mold 2 and the movable mold 3. A plurality of holding pins 6 are provided so as to pass through the fixed mold 2 and the movable mold 3. When the molten molding resin flows into the molding die 1, these flexible pins 5 Hold it still. FIG. 1 shows a state of the molding die 1 before the molding resin is filled.

A molten molding resin is injected from an injection port (not shown) into the molding die 1 in the state shown in FIG. FIG.
Shows a state of the molding die 1 after the resin is injected. In this case, it is necessary to hold the flexible hose 5 firmly by the holding pin 6 so that the flexible hose 5 does not move due to the pressure of the injected resin. Further, a mesh is selected so that the melt-molded resin does not enter the mesh of the flexible hose 5, or a means such as a multilayer knitting structure is adopted. In addition, when it is not necessary to consider the background, even if the molten resin enters the mesh, if the flexible hose 5 can be peeled off and removed from the molding resin, some penetration is acceptable.

After the injected resin is cooled and solidified, the end of the flexible hose 5 is pulled, the diameter of the flexible hose 5 is reduced and the flexible hose 5 is deformed by stretching, peeled off from the solidified molding resin, and the flexible hose 5 is removed from the molding die 1. Remove it. This state is shown in FIG.

FIG. 4 shows a state in which the movable mold 3 is moved, the molding die 1 is opened, and the tubular resin product 7 is taken out. For releasing the product 7 from the molding die 1, an ejector pin (not shown) can be used if necessary. When the holding pin 6 is used, the circular pipe resin product 7 is used.
The hole of the holding pin 6 is formed. This is made by filling the hole after taking out the product, or by filling the molding resin of FIG. 2 and solidifying the holding pin 6 by the thickness of the circular pipe. It is necessary to take measures such as retreating and further filling the formed space with a molding resin.

As described above, when a circular tube having a free curvature, such as an intake manifold, is manufactured by resin molding, it is difficult to easily manufacture it by the conventional technique. By using a flexible hose woven into a mesh as a core,
It has become possible to easily manufacture circular resin products having a free curvature.

[Brief description of the drawings]

FIG. 1 is a view showing a state before a molding resin is injected, which is incorporated in a molding die in a state where a flexible hose is closed.

FIG. 2 is a view showing a state after a molding resin is injected into a molding die.

FIG. 3 is a diagram showing a state in which a flexible hose is drawn out of a molding die after solidification of an injected resin.

FIG. 4 is a view showing a state in which a molding die is opened and a circular resin product is taken out.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Resin molding die 2 ... Fixed mold 3 ... Movable mold 4 ... Cavity 5 ... Flexible hose 6 ... Holding pin 7 ... Circular tube resin product

Claims (2)

[Claims] 1. A method of manufacturing a circular tube having a free curvature by resin molding, comprising: a resin molding die having a shape outside a circular tube having a free curvature formed by combining a fixed die and a movable die. After incorporating and fixing a flexible hose in which metal is knitted in a mesh shape into the cavity, the molten resin is poured into the resin molding die to be cooled and solidified. A resin tube having a free curvature, wherein the resin molding die is opened and the resin product is taken out of the tube. 2. The method according to claim 1, further comprising a holding pin for supporting the flexible hose incorporated in the resin molding die.