JPH0212169B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a resin hydraulic cylinder for automobiles (hereinafter referred to as a cylinder).More specifically, the present invention relates to a resin-made hydraulic cylinder for automobiles (hereinafter referred to as a cylinder). , relates to a manufacturing method for manufacturing highly accurate cylinders.

As for conventional technology, in order to improve the accuracy of the inner diameter dimension and the roughness of the surface in contact with the seal in resin cylinders, the specification of Japanese Patent Application No. 11759/1983 entitled ``Method for Molding Hydraulic Cylinder'' describes the use of glass in polyamide resin. A method is described for forming a cylinder having a smooth inner surface by incorporating fibers as a reinforcing material to form the outer part of a hydraulic cylinder, and then injection molding the inner part of the cylinder into a polyamide resin that does not contain glass fibers. However, this method requires two types of molds, and a two-layer cylinder structure has been proposed as an improved method.In this manufacturing method, a tube made of unreinforced resin corresponding to the inner layer cylinder is molded in advance, and the tube is As an insert member, there is a manufacturing method in which resin containing glass fiber is injection molded as an outer layer cylinder to integrate it, but in this method, resin containing glass fiber flows into the gap between the cylinder core pin and the inner surface of the tube from the end surface of the tube. The resin adheres to the entire or part of the inner surface of the tube, and the surface roughness deteriorates to about 0.9μRZ. At the same time, the resin containing glass fibers flows into the inner surface of the tube, making it impossible to stably obtain the desired two-layer structure. Can not.

That is, this can be explained using the cylinder molding situation diagram shown in Figure 5. In A, 1' is a cylinder made of reinforced resin mixed with glass fiber, 2' is a tube for insert, 3' is a fixed mold, and 4' is a cylinder. is the cylinder core pin, and 5' is the gap between cylinder core pin 4' and tube 2'.The cylinder core pin moves on the inner surface of the tube, so the clearance at 5' is about 0.1 to 0.2 mm. When molding a cylinder with a two-layer structure such as
The reinforcing resin flows into 5′ as shown in 1′a, and flows into the entire inner surface of the tube as shown in 1′b of C, making it impossible to obtain a good surface roughness and stabilizing the two-layer structure. The disadvantage was that it could not be made.

The present invention improves the above-mentioned drawbacks, and provides a two-layer hydraulic cylinder having an inner layer (tube) made of an unreinforced resin material and an outer layer made of a reinforced resin material mixed with a reinforcing material such as glass fiber. ) Molding an insert tube that shrinks when temperature rises and has good inner surface roughness using a resin that has adhesive properties with the outer layer resin, such as nylon or non-reinforced resin such as adhesive-treated Teflon, (2) After inserting the tube into the cylinder core pin of the mold, it is held in a fixed mold, and (3) the outer layer of the cylinder is made by injection molding a reinforced resin containing 10 to 50% of reinforcing material such as glass fiber. and (4) inserting the tube made of the unreinforced resin to manufacture a cylinder with a two-layer structure.

Cylinder manufactured by this method inserts a tube that shrinks when the temperature rises above 50℃, so the tube shrinks due to the heat from the mold and tightly adheres to the cylinder core pin of the mold. Even if reinforcing resin is injected, there is no gap between the tube and the cylinder core pin, so the reinforcing resin does not flow into the inner surface of the tube, so the inner surface of the insert member tube remains in its original good condition. Since the surface roughness of 0.3 μRZ can be maintained as is and the inner layer and outer layer are bonded, it is possible to manufacture a hydraulic cylinder with a two-layer structure of an inner layer made of unreinforced resin and an outer layer made of reinforced resin.

1 to 4, 1 is a hydraulic cylinder, 2 is an outer layer made of resin using reinforcing material, 3 is nylon,
PVC, and a sodium treatment method in which metal sodium is immersed in a solution of liquid ammonia.
This tube is made of Teflon, polyethylene, etc. that has been treated with adhesive properties such as glow discharge treatment or corona discharge treatment, and has been given heat shrinkability. Figure 2 shows a mold for injection molding the cylinder, with 4
5 is a fixed mold, 5 is a movable mold, and 6 is a cylinder core pin.

In the above mold structure, after the tube 3 is inserted into the cylinder core pin, it is moved into the fixed mold 4 and the reinforcing resin 2 is injected, and the tube 3 is inserted. Due to the temperature of the heated cylinder core pin, the tube 3 comes into close contact with the cylinder core pin as shown at 7, and the reinforcing resin 2 does not flow into the inner surface of the tube. After molding, if the temperature of the cylinder core pin decreases, loosening will occur between the tube and the cylinder core, allowing the cylinder to be easily removed. As a result, the inner surface of the tube was able to maintain its original surface roughness of 0.3 μRZ.
It is possible to stably manufacture a cylinder with a two-layer structure.

Although the cylinder in this embodiment shows a clutch M/e used in a clutch system, the molding method of the present invention can also be applied to other moldings such as M/e used in a brake system. It is.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a completed hydraulic cylinder manufactured using the manufacturing method of the present invention, Fig. 2 is an enlarged sectional view of the injection process of the hydraulic cylinder, Fig. 3 is a sectional view of the flow of resin in injection molding, Figure 4 is a sectional view of only the hydraulic cylinder. FIG. 5 shows a conventional method for manufacturing a hydraulic cylinder, in which A is a cross-sectional view of the injection process, B is a cross-sectional view of the resin flow in the injection process, and C is a cross-sectional view of the hydraulic cylinder. 1... Hydraulic cylinder, 2... Outer layer, 3... Inner layer (tube), 4... Fixed mold, 6... Cylinder core pin.

Claims (1)

[Claims] 1. In a method for manufacturing a hydraulic cylinder in which the outer layer is made of reinforced resin mixed with glass fiber and the inner layer tube is made of unreinforced resin, nylon, PVC,
An inner layer tube is formed from a heat-shrinkable resin made of adhesive-treated Teflon and polyethylene, and then the tube is inserted into the cylinder core pin of the injection mold, and the cylinder core pin is fixed. A method for manufacturing a hydraulic cylinder having a two-layer structure of an outer layer and an inner layer, which is held in a mold, then injection molded with a reinforced resin of the outer layer, and inserted with a tube of the inner layer.