JPS6155418A - Coil made of synthetic resin - Google Patents

Abstract

PURPOSE:To obtain excellent profile and size stability and rigidity by melting and spinning thermoplastic polyester, molding a monofilament with a specific extension multiplying factor and a diameter into a spiral, and specifying its spring index and pitch interval. CONSTITUTION:A monofilament with a diameter of 1.2-5.0mm. made by melting and spinning thermoplastic polyester and extending it at an extension multiplying factor of three times or more is molded into a spiral, the spring index D/d is set to 3-7, where D is the diameter of the spring and (d) is the diameter of the monofilament, and the pitch interval is set to DX0.5(mm.) or less. In this case, polyethylene terephthalate or the like is used for thermoplastic polyester. The polyester monofilament is produced by extruding a molten polymer through a spinning nozzle and spinning it, cooling it and applying oil to it, then extending and heat-fixing it. Accordingly, excellent rigidity and profile and size stability can be obtained.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention provides a synthetic resin spring that is strong, has excellent shape stability, dimensional stability, rust resistance, electromagnetic insulation resistance, light weight, and chemical resistance. The purpose of this invention is to provide a synthetic resin spring that is particularly useful as a light load compression spring for various mechanical devices, miscellaneous goods, miscellaneous goods, and the like.

(Prior art) Metal wire has been used exclusively as a material for industrial springs used in the mechanical and electrical fields, but these tend to rust, have poor durability, cannot be colored, and are not conductive. There are problems such as being sharp, easily causing injury or accidents, and being heavy and difficult to handle and store.Recently, synthetic resins have been attracting attention as an alternative material to these conventional metals. .

For example, as a spring made of synthetic resin,
An integrally molded spring described in Japanese Patent No. 4-27470 is known, but conventional synthetic resin compression springs have poor toughness and shape stability when used as compression springs,
In particular, the maximum load that can be applied is small, and it is easy to cause fatigue and deformation, so the actual situation is that its uses are extremely limited.

(Problems to be Solved by the Present Invention) Therefore, the present inventors conducted extensive studies with the aim of obtaining a synthetic resin spring that can be applied with a large maximum load and has excellent toughness, shape stability, and dimensional stability. As a result, it was discovered that a spring with a specific shape made by shaping a specific synthetic resin monofilament exhibits performance that is significantly stronger and has superior shape stability compared to conventional synthetic resin compression springs, and the present invention reached.

(Means for solving the problems) In other words, the present invention melt-spun thermoplastic polyester,
Diameter 1.2 obtained by stretching to a stretching ratio of 3 times or more
~5. It is made by shaping a monofilament of Qmm into a circular V shape, and has a spring index of 3 to 7 expressed as D/d from the diameter of the spring and the diameter d of the monofilaments 1 to 1, and has a pitch interval of Dxo.

The present invention provides a synthetic resin spring characterized by having a thickness of 5 (mm) or less.

Examples of the thermoplastic polyester used in the present invention include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polyethylene naphthalate, and mutual copolymers thereof, among which polyethylene terephthalate is preferably applied. These thermoplastic polyesters preferably have a solution viscosity (IV) of 0.6 or more as measured with an orthochlorophenol solution. The thermoplastic polyester may also contain conventional additives such as heat resistant agents, weathering agents, UV stabilizers, combustible agents, antistatic agents, abrasives, plasticizers, nucleating agents, lubricants and colorants. Among them, it contains colorants such as various pigments and dyes1! It becomes possible to color the 1c spring in the desired color and remove it.

The polyester monofilament as a material constituting the spring of the present invention is manufactured by a commonly known method consisting of extrusion spinning a molten polymer from a spinneret, cooling it, applying an oil agent, stretching it, and heat-setting it as necessary. be able to.

However, the diameter of the monofilament used is 1, 2 to 5.
0mm, especially in the range of 1.5 to 4.0mm; if it is less than 1.2IIIm, the toughness as a spring cannot be expected; 5. If it exceeds 0 mm, it becomes difficult to form into a spring, which is not preferable.

Moreover, monofilament is more than 3 times, especially 3.5 to 6.
It has been stretched to a 5x stretching ratio and weighs 30 kg.
It is important that the spring has a strength of 2 or more and an elongation of 100% or less, and if it is not stretched or the stretching ratio is less than 3.0 times, the shape and dimensional stability of the spring obtained by shaping will deteriorate. Not only is it inferior, it gradually deforms during use, but it is not desirable because it cannot be expected to have sufficient toughness. Such stretching of the monofilament can be carried out in one stage or in multiple stages of two or more stages, using conventional hot rollers, hot bottles, hot plates, and the like.

-1- For forming the monofilament into a spring, the monofilament was preheated to a temperature close to the melting point of polyester.
! Wound continuously at appropriate pitches around 8 rotating rods with a diameter equal to the inner diameter of the spring.
This can be done by cooling while cooling.

In the synthetic resin spring of the present invention, it is important that the spring index expressed by D/d is in the range of 3 to 7 from the spring diameter (outer diameter) I) and the monofilament diameter d. If the spring index is less than 3, the workability will decrease and a spring with a desired shape cannot be obtained, and if it exceeds 7, the toughness of the spring will decrease, which is not preferable. The spring of the present invention can have a cross-sectional shape other than a circle, such as an ellipse or a rectangular shape such as a triangle or quadrilateral. The spring index is determined from the maximum diameter of the circle (square) that is tangent to the square.

In addition, the pitch interval P between each helix in the synthetic resin spring of the present invention is less than or equal to the spring diameter Dx0.5+nm;
xo, 311IIIl or less, and P
If Dxo exceeds 5+nm, the toughness and shape stability of the spring will decrease, which is not preferable.

As shown in the plan view of the spring of the present invention, the spring of the present invention has a fixed shape in which the monofilament is spirally wound, and corresponds to a fixed number of turns when a load is applied to the monofilament. It has the characteristics that not only can it withstand quite high loads, but it also takes a long time to deform when such high loads are repeatedly applied, and has extremely excellent shape and dimensional stability. , especially useful as compression springs.

(Example) Polyethylene terephthalate 1 or more having a solution viscosity (IV) of 0.65 is melt-spun and then stretched 5.25 times, or
Or, without stretching, the IC diameter (
d) Obtain a monofilament having:

Next, the above-mentioned polyethylene terephthalate monofilament, which had been softened by heating to a temperature higher than the glass transition temperature, was continuously wrapped around iron round bars having various diameters and cooled.
By removing it, a spring with the spring diameter (D), spring index (D/d > and pitch interval (P) shown in Table 1) is created.
Two types of springs were created.

Table 1 shows the evaluation results of the toughness and shape stability of the obtained springs.
It is also shown in .

The toughness of the spring was determined by subjecting the springs cut to the quality shown in Table 1 with a constant number of turns of 8 to a constant speed elongation tensile tester.
This was then compressed by gradually applying a load, and evaluated by determining the maximum load until each helix was in complete contact with each other and the pitch interval became 0.

In addition, shape stability was determined by measuring the length of the spring (11) after repeating the above maximum load 105 times, and measuring its initial length (6).
From o), (fo)-(ヱ1)/(I!, o)xlo
o was calculated and evaluated.

Table-1 *Measurement after repeating 1 to 104 times *Measurement after repeating 2 to 2x104 times As is clear from the results in Table-1, the spring of the present invention (N0
2.6.8.11 and 12) have a large maximum load,
It had excellent toughness and good dimensional and shape stability after restoration.

On the other hand, a spring using unstretched monofilament (N01
．． 5. and 7), springs using monofilament with d less than 1.2w1m (N09 and 10) and D/d
None of the springs where P exceeds 7 (No. 3) satisfy both toughness and shape stability. Also, when P is d
The spring (No. 4), which is too large (x0.8), has a high maximum load but is poor in shape stability.

(Effects of the Invention) The synthetic resin spring of the present invention is strong and has excellent shape stability, dimensional stability, rust resistance, electromagnetic insulation resistance, light weight, and chemical resistance, and is particularly resistant to deflection under light loads. Because it contains a lot of acid, it is useful as a light-load compression spring for various machines, electrical equipment, miscellaneous goods, and miscellaneous goods that are designed to sensitively detect displacement under small loads.

[Brief explanation of drawings]

The drawing is a plan view of the synthetic resin spring of the present invention. d... Monofilament diameter D・・・Spring diameter P・・・・・・Pitch interval

Claims (1)

[Claims] A monofilament with a diameter of 1.2 to 5.0 mm, which is obtained by melt-spinning thermoplastic polyester and drawing it to a draw ratio of 3 times or more, is formed into a spiral shape, and the spring diameter D and the monofilament diameter d are formed. and the spring index expressed as D/d is 3 to 7, and the pitch interval is D x 0.5.
(mm) or less.