JPS6032067B2 - Molding method of thermoplastic resin valve - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides, for example, a piston in a hydraulic cylinder.
A lock valve for a hydraulic cylinder that is configured to be able to freely switch between a state in which the piston can slide against the cylinder and a state in which it is fixed by opening and closing oil passages formed to allow the cylinder chambers on both sides to communicate with each other. The present invention relates to a method for molding a valve, the valve body of which is molded from a thermoplastic resin material.

[Prior art]

Such resin-molded valves tend to have problems with the sealing performance of the valve seat due to distortion during the molding process.

Therefore, in the past, after the molding of the thermoplastic resin valve body was completed, that is, after the molded valve was cooled and completely hardened, a member having the same external shape as the support surface of the valve body for the valve seat was used. A method of caulking was being explored in which the valve seat was applied to the valve seat and hammered with a hammer to deform the valve seat and make it conform to the valve body (as a similar technique, for example, Publication No. 3006).
[Problems to be solved by the invention] Therefore, since the above-mentioned conventional technology involves plastic working by blowing after cooling and hardening,
The large external force required for caulking causes changes in the internal stress of the valve body, and over time, due to changes in internal stress, the shape of the valve seat surface deforms, causing leakage, damage, and deformation during use. This method has the drawback of producing many defective products that are likely to cause problems such as the following.

When molding thermoplastic resin valves, an annealing process is performed to reheat the valve body after molding in order to remove residual stress in the valve body. It is an object of the present invention to make advantageous use of the reheating treatment of the main body to improve the accuracy of the contact surface of the valve seat against the valve body.

[Means for solving problems]

As a technical means for solving the above problems, in the present invention, when reheating and heat-treating a valve body molded using a thermoplastic resin material, the valve seat to be internalized is Heat treatment is performed while pressing a valve body with a certain force with an outer surface that is equal to the contact surface of the valve body or the valve seat.

[Operation] When the valve body is reheated and heat treated, the valve body is heated to a temperature range where it can be plastically deformed.
At this point, if the valve body or a member with the same external shape is pressed against the abutment surface of the valve seat, the abutment seat will be formed correctly following the shape of the valve body or member, and even smaller pressing force will be required. Since the so-called annealing process is a process for removing internal residual stress in the valve body, no distortion of the valve body occurs due to pressing of the valve body or member.

〔Effect of the invention〕

... The pressing force required for processing the valve seat is only 4 mm) Since the valve body is reheated to a temperature range where it can be plastically deformed, there is no risk of changing the internal stress of the valve body. Incorporating the work to ensure sealing performance by blending the valve seat and valve body into the valve molding process makes it very simple, easy, and
It can be done efficiently and contributes to productivity improvement.

'.

) Furthermore, the valve body 1 is not subjected to an annealing process, that is, reheated to remove internal residual stress, after it has been formed and cooled and hardened, rather than using the heat-processed state during the intended forming process. Since it takes advantage of the state,
In other words, annealing removes internal distortion during the cooling process after molding, and since time is given to remove the distortion, use this time to press the valve body or member. Since the valve seat can be formed using the same method, no distortion occurs due to this pressing process, and the valve seat can be formed with even higher sealing accuracy. EXAMPLE Next, an example of the method of the present invention will be explained with reference to the drawings.

The drawing shows a lock valve which is an example of the method of the present invention, which opens and closes an oil passage 6 formed in a piston 4 of a hydraulic cylinder so as to communicate cylinder chambers 5a and 5b on both sides with each other. The piston 4 is provided to be switched between a slidable state and a fixed state relative to the cylinder 5, and this includes a valve body 1 made of thermoplastic resin that also serves as the piston 4, and a valve body 1 of this valve body 1. A pole-shaped valve body 3 corresponding to the seat 2 and a spring 7 are held in a state where the valve body 3 is pressed against the valve seat 2 side, and an oil path 8 is formed between the valve body 1 and the valve body 1. Normally, a spring retainer 9 which can be iron-mounted is assembled to the main body 1 so that the valve body 3 is elastically adhered to the valve seat 2 to close the oil passage 6.

In the figure, 10 is an operation odor provided at the tip of the piston rod 4A connected to the piston 4 so that the valve body 3 can be moved in the opening direction against elastic bias, and 11 is the piston 4 and cylinder 5. It is an oil-tight ring inserted between it and the wall. To fully form the lock valve with the above structure, the valve body 3, spring 7, and spring retainer 9 are assembled to the finished valve body 1, which is formed into a predetermined shape using thermoplastic resin material and cooled and hardened. , the valve body 3 is fixedly held in a state where it is pressed by the force of the spring 7 on the valve seat 2, and in this state, the valve body 1 is reheated to a temperature range at which it can be plastically deformed, and heat treatment (annealing treatment) is performed. Then, before the valve body 1 is cooled and hardened, the valve seat 2 is deformed and molded into a shape that fits the valve body 3 by the above-mentioned pressing. Therefore, in order to process the valve seat 2 to fit the valve body 3 by directly using the valve body 3 to be installed, the valve body 3 is attached to the valve body 3 and the valve body 3 is attached to the valve seat 2 using a spring or the like. Since the valve assembling work can also be used to secure the sealing performance, the number of work steps as a whole can be reduced and workability can be further improved.

In addition, in the above-mentioned embodiment, the valve body 3 was shown in a ball shape, but
For example, the present invention is applicable even to a dish-shaped valve body 3.

Furthermore, the method of the present invention can be applied to various valves such as check valves, relief valves, and safety valves in addition to the lock valves of the embodiments.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view illustrating an embodiment of the method for molding a thermoplastic resin valve according to the present invention. 1... Valve body, 2... Valve seat, 3...
・Valve body.

Claims (1)

[Claims] 1 When the valve body 1 molded using a thermoplastic resin material is reheated and heat-treated, the valve seat 2 is heated with the valve body 3 to be installed or the contact surface of the valve body 3 with the valve seat 2. 1. A method for molding a thermoplastic resin valve, which comprises pressing a member having an external surface with a certain force and subjecting it to heat treatment.