JPS59143627A - Manufacture of hydraulic cylinder made of resin - Google Patents

Abstract

PURPOSE:To enable to manufacture a cylinder of double-layer structure, by a method wherein a core pin of a cylinder is kept within a stationary metal die and then an inner layer tube is inserted into an outer layer of strengthened resin molded through injection molding after insertion of the inner layer tube molded out of resin having thermal contraction into the core pin of the cylinder of an extrusion molding die. CONSTITUTION:An insertion tube 3 which is contracted through a rise of temperature and having favorable roughness on the inside is molded by making use of an outer layer resin and adhesive resin, for example, unstrengthened resin such as nylon or teflon to which adherence treatment has been made. Although the tube 3 is inserted when strengthened resin 2 is injected by moving the tube 3 within a stationary metal die after insertion of the tube 3 into a core pin of a cylinder, in this instance, the tube 3 adheres closely to the core pin of the cylinder and the strengthened resin 2 does not flow into the inside of the tube due to a temperature of the core pin of the cylinder heated more than a temperature of about 50 deg.C. When the temperature of the core pin of the cylinder is lowered after molding, the cylinder can be taken out easily and the cylinder of double-layer structure can be formed stably as slackness is generated between the tube and the core of the cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a hydraulic cylinder for self-hffi made of resin (hereinafter referred to as cylinder 1).
This relates to a production method for manufacturing highly accurate cylinders by injection molding a complex cylinder (1*) for the purpose of weight reduction and labor saving. It is.

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. 58-11759 ``Method for Molding Hydraulic Cylinder'' describes the use of glass in polyamide resin. fiber? A method of forming a cylinder with a smooth inner surface by mixing it as a reinforcing material to form the outer part of a hydraulic cylinder, and then injection molding it into a polyamide resin that does not contain glass fibers on the inner side of the cylinder is described. However, this method requires two types of molds, and a two-layer cylinder structure has been proposed as an improved method.
There is a manufacturing method for this in which a tube portion made of unreinforced resin corresponding to an inner layer cylinder is molded in advance, and the whole tube is integrally molded by injection molding as an outer layer cylinder of resin containing glass fiber as an insert member. The method is such that resin containing glass fibers 2 flows into the gap between the cylinder core bottle and the inner surface of the tube from the end surface of the tube, solidifies all or part of the inner surface of the tube, and the surface If becomes 0.
As the temperature deteriorates to about 9μRZ, the resin containing glass fibers flows into the inner surface of the tube, making it impossible to stably obtain °II sound even with the two layers as expected.

That is, 7'L Kai? J＞ According to the cylinder molding situation diagram in Figure 5, in (A), r is the cylinder with glass fiber mixed in, 2 is the reinforcing resin, 2' is the tube for the insert, 3' is the fixed mold, 4' is a cylinder core pin, and 5' is a gap between the cylinder core pin 4' and the tube 2', so that the cylinder core pin moves on the inner surface of the tube, so the gap at 5' is 0.1 to 0.2. When molding a cylinder with such a two-layer structure, as shown in (b), the pressure at the time of molding causes the gap 5' to be filled with l"a.
As shown in 1b, the reinforcing resin flows into the entire inner surface of the tube as shown in 1b of (c), making it impossible to obtain a good surface roughness and making it impossible to stably create a two-layer structure. Togai Tsuta.

The present invention has improved the above-mentioned drawbacks, and has 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. In a hydraulic cylinder with a two-layer structure, (1) a resin that has adhesion to the outer layer resin, such as nylon or an adhesive-treated tearless non-reinforced resin, is used to shrink due to temperature rise, and has inner surface roughness. (2) After inserting the tube into the cylinder core bin of the mold, hold it in a fixed mold; (8) Containing 210-50% of reinforcing material such as glass fiber. A reinforcing resin is injection molded to form the outer layer of the cylinder, and (4) a tube made of the thermoplastic resin is inserted to create a two-layer structure σ) cylinder'? i: To be manufactured.

Cylinders manufactured by this method insert tubes that shrink when the temperature rises by more than 50°C, so the tubes shrink due to heating from the mold.
Because it is in close contact with the cylinder core pin of the mold, there is no gap between the tube and the cylinder core pin even when reinforcing resin is injected, so the reinforcing resin does not flow into the inner surface of the tube) Therefore, the inner surface of the insert member tube can maintain its original good surface roughness of 0.8μRZ,
In addition, since the inner layer and the outer layer are bonded, it is possible to manufacture a hydraulic cylinder having a two-layer structure of an inner layer made of unreinforced resin and an outer layer made of reinforced resin.

The following is a detailed explanation using examples and FIGS. 1 to 4.
7"L, 1 is the hydraulic cylinder, 2 is the outer layer made of resin using reinforcing material, and 3 (gonylon).

PVC, Teflon with X-contact plate, polyethylene, etc. 2
14.It is a tube that is used and has heat shrinkability. Second
The figure shows a mold for injection molding the cylinder, including a 4-piece fixed mold, 5 a movable mold, and a 6C cylinder core bottle.

In the above mold structure, after inserting the tube 8 into the cylinder core bin, the tube 8 is moved into the fixed mold 4 and the reinforcing resin 2 is injected. Due to the temperature of the cylinder core bottle heated to , the reinforcing resin 2 does not flow into the inner surface of the tube because the tube 3 is tightly attached to the cylinder core bottle as shown in (7).

After forming and forming, if the humidity of the cylinder core pin decreases T7''l, the tube and cylinder core will become loose and the cylinder can be easily taken out.As a result, the inner surface of the tube will have its original surface roughness. Can hold 0.8μRZ,
It is possible to stably manufacture a cylinder with a two-layer structure.

Although the cylinder in this example shows a clutch M/e used in a clutch system, the molding method of the present invention can also be applied to molding of 8n M/θ 0) used in a brake system. It is something.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a completed hydraulic cylinder manufactured by the manufacturing method of the present invention, Fig. 2 is an enlarged cross-sectional view of the injection process of the hydraulic cylinder, and Fig. 8 is a cross-sectional view of the resin flow n during injection molding. , FIG. 4 is a sectional view of only the hydraulic cylinder. Figure 5 shows the conventional manufacturing method for hydraulic cylinders.
(C) is a sectional view of the hydraulic cylinder. ■... Hydraulic cylinder, 2... Outer layer, 8.・Inner layer (tube), 41... Fixed mold, 6... Cylinder core bin Patent applicant Aisin Seiki Co., Ltd. Representative Reio Nakai No. 1 No. 31 < 1 4' in the figure (¥J)

Claims (1)

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