JPH04229227A - Manufacture of rubber hose - Google Patents

Abstract

PURPOSE:To eliminate a defect where at the time of manufacturing of a radiator hose for an automobile, when the hose of an uncured elastic material is molded by outserting a flexible and linear (straight) mandrel possessing a spirally wound screw, spirally wound screw marks are left behind in an inside mandrel and a leak in a joint part with an opposite pipe or pressure resistance of the rubber hose is deteriorated. CONSTITUTION:To vulcanized and molds the title rubber hose by interposing a heat-resistant elastic tube 3 between a flexible mandrel 2 and unvulcanized rubber hose 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing rubber hoses used for automobile radiator hoses and the like.

0002

2. Description of the Related Art A conventional method for manufacturing a hose of a desired shape is found in, for example, Japanese Patent Laid-Open No. 85736/1983. This method involves extrapolating a hose of uncured elastic material onto a flexible straight mandrel with a spirally wound thread, inserting an inner mandrel into the assembly, and vulcanizing the hose into the desired shape. After molding, the hose was removed from the inner mandrel and flexible mandrel.

0003

[Problems to be Solved by the Invention] This conventional technology has disadvantages such as the spiral winding thread marks of the mandrel on the inner wall of the hose, which may cause leakage at the joint with the mating pipe or reduce the pressure resistance of the hose. . The present invention aims to prevent the occurrence of this spiral defect and eliminate the above-mentioned drawbacks of the hose.

0004

[Means for solving the problem] An unvulcanized rubber hose is fitted onto a flexible straight mandrel, and the unvulcanized rubber hose and the flexible mandrel are inserted into an inner mandrel to form and cure the desired shape. In the method of manufacturing a rubber hose to be cured, a heat-resistant elastic tube 3 is interposed between the flexible mandrel 2 and the unvulcanized rubber hose 1, and the hose is cured and molded. Examples of the material for the heat-resistant elastic tube include acrylic rubber, fluororubber, silicone rubber, and EPDM. The thickness of the tube needs to be such that when it is extrapolated onto the flexible mandrel, the shape of the spirally wound thread of the flexible mandrel does not protrude from the outer peripheral surface, and is usually 0.3 to 10 mm, preferably 0.3 to 10 mm. 3-5mm
The thickness should be appropriate depending on the material and hardness of the rubber hose to be molded.

[0005]

[Operation] According to the method of the present invention, the heat-resistant elastic tube 3 interposed between the flexible mandrel 2 and the unvulcanized rubber hose 1 absorbs the spirally wound screw marks on the flexible mandrel 2, and Prevents spiral marks from forming on the inner wall of the rubber hose.

[0006]

EXAMPLES Example 1 First, as shown in FIG. 1(a), the outer surface of a flexible mandrel 2 was coated with a heat-resistant elastic tube 3. In this case, the elastic tube 3 and the flexible mandrel 2 may be bonded or not bonded. The heat-resistant elastic tube 3 is made of acrylic rubber in this example. Next, Figure 1 (
As shown in b), an EPDM unvulcanized rubber hose 1 was inserted outside. As shown in FIG. 1(c), the assembly was extrapolated onto the inner mandrel 4 and formed into a predetermined bent shape, and then vulcanized at 154°C. After vulcanization, the heat-resistant elastic tube 3 and the inner mandrel 4 were removed, and as a result, a rubber hose with a curved shape suitable for an automobile radiator hose and a smooth inner surface was obtained.

Embodiment 2 As shown in FIG. 2(a), the heat-resistant elastic tube 3 is inserted into the inner surface of the unvulcanized rubber hose 1, and as shown in FIG. 2(b), an elastic A straight flexible mandrel 2 with a spiral wound thread was inserted into the inner surface of the tube 3. The assembled body is extrapolated onto the inner mandrel 4 having the desired curved shape for the hose as shown in Figure 2(c), and after being assembled and molded, it is vulcanized in the same manner as in Example 1, and thereafter a rubber hose product is obtained in the same process. Ta. By this method, a good product similar to Example 1 was obtained.

[0008]

Effects of the Invention: With the rubber hose manufacturing method of the present invention, the spiral irregularities on the outer surface of the flexible mandrel during molding and vulcanization are absorbed by the heat-resistant elastic tube material interposed between the mandrel and the hose. The hose was then vulcanized and molded with the inner surface smooth, resulting in a good product with no unevenness on the inner surface.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of each step in Example 1 of the present invention.

FIG. 2 is a cross-sectional view of each process in Example 2 of the present invention.

[Explanation of symbols]

1 Unvulcanized rubber hose 2 Flexible mandrel 3 Heat-resistant elastic tube 4 Inner mandrel

Claims (1)

[Claims] Claim 1: A rubber hose in which an unvulcanized rubber hose is extrapolated onto a flexible straight mandrel, and the unvulcanized rubber hose and the flexible mandrel are inserted into an inner mandrel to be formed into a desired shape and vulcanized. A method for manufacturing a rubber hose, characterized in that a heat-resistant elastic tube 3 is interposed between the flexible mandrel 2 and the unvulcanized rubber hose 1, and vulcanization and molding are performed.