JPS5824266B2 - Manufacturing method of drive belt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a drive unit for use in small precision transmission mechanisms such as magnetic recording devices, phono motors, and self-recording devices.

related to the root and its manufacturing method.

Although the power to be transmitted in this type of transmission mechanism is relatively small, transmission that faithfully follows the movement of one drive shaft is often required, and transmission errors such as backlash and slip must be kept to a minimum. No.

Synthetic rubbers such as chloroprene rubber and urethane rubber conventionally used for this purpose are in practical use, but they lack strength and tend to have uneven thickness and strength, so they cannot be said to be fully satisfactory.

Ideally, the belt should be thin in order to reduce the difference in circumference between the inner and outer surfaces of the belt when it is surrounded by pulleys. The material of the belt must have considerable strength.

The method of reinforcing the belt with thread or cloth, which is generally used to compensate for the drawbacks of synthetic rubber, is not preferred because it increases the thickness of the belt and complicates the manufacturing process.

Some attempts have been made to use thermoplastic elastomers such as polyurethane, polyvinyl chloride, and styrene-butadiene copolymers, but if they are not reinforced with reinforcing materials, they will gradually undergo permanent deformation and elongation under tension, which is the so-called creep phenomenon. Even if the characteristics are good, it cannot withstand long-term use.

As a result of extensive research into drive belts used in precision power transmission mechanisms and methods for manufacturing the same, the inventors of the present invention have found that polynisal block copolymers, especially those obtained by stretching or heat-treating them, are suitable as materials for this purpose. We discovered this and arrived at the present invention.

That is, the first aspect of the present invention is a seamless drive bell i made of a polyester block copolymer.

The second aspect of the present invention is a seamless drive belt characterized by punching a polyester block copolymer sheet or film into circular shapes, or cutting a polyester block copolymer pipe or tube into rings. This is the manufacturing method.

The polyester block copolymer in the present invention refers to a linear block copolymer consisting of a high melting point crystalline polyester segment and a low melting point non-quality polymer segment.

The high melting point crystalline polyester segment of the polyester block copolymer forms a fiber-forming high polymer with its constituent components alone, and contains ethylene tereclate units,
A typical example is one whose main component is an aromatic polyester having a bond at the P-position, such as a tetramethylene ethylene reflex clay 1 unit.

Here, as dibasic acid components, isophthalic acid, adipic acid,
It may also partially contain sebacic acid, dodecanedioic acid, etc.

The average molecular weight of the high melting point crystalline polyester segment in the polyester block copolymer is 400 to 10,0
00 is preferred.

The low melting point non-quality segment is one that exhibits a substantially amorphous state in the polyester block copolymer, such as polyether, aliphatic linear polyester, polylactone, etc.
That is, polyethylene oxide glycol, polytetramethylene oxide glycol, polyethylene adipate, polyneopentyl sebacate, poly-ε-caprolactone, and the like.

Specific examples of the polyester block copolymer include polyethylene terephthalate/polyethylene oxide block copolymer, polytetramethylene ethylene terephthalate/polytetramethylene oxide block copolymer, polyethylene terephthalate/poly-ε-caprolactone block copolymer, Typical examples include polyethylene terephthalate/polyethylene adipate block copolymer and polyethylene terephthalate/polyneopentyl sebacate block copolymer.

The hardness or elasticity of such a polyester block copolymer can be adjusted by adjusting the composition ratio of the high melting point crystalline polyester segment and the low melting point non-grade polymer segment. A material with uniform hardness can be obtained as desired, and its physical properties can also be adjusted by stretching it, or by further heat treating it.

For normal purposes, the weight proportion of high melting point crystalline polyester segments is preferably in the range of 20 to 80%.

To create a 1-drive belt from a polyester book copolymer, either mold the copolymer into a film or sheet and punch it into a ring shape, or mold the copolymer into a cylindrical shape. It is preferable to cut this into rounds.

It is formed into a band or string, cut to size, and joined at both ends to create a ring.

This is inappropriate for manufacturing a drive belt used in a precision transmission mechanism, which is the object of the present invention.

This is because the thickness and hardness of the joints differ, and this unevenness in thickness and hardness causes fatal conduction errors.

A polyester block molded into a seamless circular ring.

Lock copolymers are already used in small precision transmission mechanisms.
It has sufficiently excellent properties as a drive belt, and may be used as is for this purpose in some cases, but it is preferable to stretch it because its properties are further improved.

If the stretched material is heat treated, its properties can be further improved.

That is, by stretching or further heat-treating it, the thickness can be reduced while maintaining the strength, and the creep phenomenon under tension is further reduced and the recoverable elastic deformation area is increased.

Since the hardness or elasticity changes when stretched or further heat treated, the high melting point crystalline polyester segment and the low melting point non-polyester segment are prepared in advance so that the desired hardness or elasticity is exhibited after the prescribed stretching or further heat treatment. It is necessary to select the composition ratio of the polymer segments.

One method for manufacturing a seamless drive belt made of such a stretched or further heat-treated polyester block copolymer is to punch out an unstretched sheet or film into an annular shape and stretch or further heat-treat it. It is to be.

That is, the second aspect of the present invention is a method for producing the drive belt described above, which comprises punching out an unstretched sheet or film of a polyester block copolymer into an annular shape and stretching it.

To stretch an unstretched sheet or film punched into an annular shape, for example, as shown in the figure, pulleys 2 and 2' each rotatable around at least two slidable rotating shafts 3 and 3' are prepared. , First, the rotation shafts 3 and 3' of the pulleys are brought close to each other, and the annular seams 1 to 1 or the film 1 are
This can be achieved by surrounding these pulleys and then sliding the rotating shafts 3, 3' away from each other while rotating the pulley 2 as shown by the arrow, and removing it when a predetermined elongation is achieved.

The purpose of rotating the pulley is to prevent uneven stretching from occurring in the portion in contact with the pulley, resulting in uneven thickness and hardness.

Although the stretching method is not limited to the method in this example, this method is the simplest and easiest.

Methods for heat-treating the stretched belt include heating under constant length, under constant tension, or under no tension, but heat-treating under constant length is easier.

An example of a method for heat treatment under a fixed length is a method in which a stretched belt is wrapped around a cylinder having a circumference equal to the desired belt length and the cylinder is heated.

The heating temperature is 30 to 1° higher than the melting point of the high melting point crystalline polyester segment in the polyester block copolymer.
A temperature 20°C lower is appropriate; if it is too high, the belt will fuse, and if it is too low, the heat treatment will be ineffective or require a long time.

In the drive belt manufactured according to the present invention, the inner circumference and outer circumference punched out in an annular shape form the left and right ears of the belt, so the difference between the inner and outer circumferences causes a difference in the stretching ratio of both ears, causing unevenness in thickness and hardness. However, theoretically speaking, it does not pose any problem in practice.

The second method for manufacturing a seamless single-drive belt made of a stretched polyester block copolymer is to cut a cylindrical unstretched pipe or tube into rings and stretch them.

That is, the third aspect of the present invention is a method for producing the drive belt described above, which comprises cutting an unstretched pipe or tube of a polyester block copolymer into rings and stretching the unstretched pipes or tubes.

According to this method, the theoretical concerns about unevenness in thickness and hardness due to differences in the inner and outer circumferences of the ring, as in the above method, are resolved, but in general, pipes or tubes have a uniform thickness compared to sheets or films. The disadvantage is that it is difficult to obtain something, so you can choose it depending on the situation and purpose.

The tube or sheet cut into rings can be stretched or further heat treated in the same manner as described above.

A fourth aspect of the present invention is a method for producing the drive belt described above, which comprises punching out a stretched sheet or film of a polyester block copolymer into an annular shape.

This method is more efficient than the previous two methods because it eliminates the need to stretch each belt-shaped object individually.

Also, unlike the previous two methods, which have a uniaxial orientation, this method has a biaxial orientation, which is characterized by strong resistance to tearing.

The belt obtained by this method can be heat-treated in the same manner as in the previous two methods, but one method is to punch out the heat-treated sheet or film after stretching.

A fifth aspect of the present invention is a method for manufacturing the above-mentioned drive belt, characterized in that a polyester block copolymer is formed into a tube shape by an inflation method, and the tube is cut into rings.

This method also has the same characteristics as the previous method, and has other characteristics such as extremely high production efficiency, although it is difficult to precisely control the diameter of the tube in the inflation method.

Also in this method, the properties of the belt obtained can be further improved by subjecting it to heat treatment.

Although the stretching and the subsequent heat treatment in the present invention improve the performance of the belt, they require a considerable amount of effort and expense, so they may be omitted as appropriate depending on the purpose.

As described above, there are various advantages and disadvantages between the methods for producing a seamless drive belt made of a polyester block copolymer according to the present invention, but these are relative and neither method can be used. The present invention provides a drive belt that is far superior to those conventionally used in precision transmission mechanisms.

Next, the present invention will be explained in detail with reference to Examples.

Example 1 Terephthalic acid, 1,4-butanediol, molecule 11oo
A polyester block copolymer synthesized from polytetramethylene glycol (polytetramethylene glycol content: 40 parts, melting point: 203°C) was extrusion molded to obtain a tube with an outer diameter of 25 mm and a thickness of 1 mm.

This tube was cut into rounds with a width of 5c7rL, then stretched between two rolls while rotating until the final tube shape was 100mm long, fixed at a constant length for 10 minutes at 160°C, and then slit into widths of 10mm. A stretched belt (■) was obtained.

The thickness of the stretched belt was 0.3 mm.

Bells I-■ and 0 below were manufactured as comparative samples.

Belt ■: Extrusion molded from the above polymer to a diameter of 100m
- Manufactured from a tube 0.3 mm thick and slit to a width of 10 mm.

Belt 0: A 100 mm diameter chloroprene belt (thickness 0.5 mm) with reinforcing cloth slit to a width of 107 nr/l.

As shown in FIG. 1, the obtained belts ■, ■ and 0 were applied to pulleys ■ and ◎ having a diameter of 20 mm, and a wear ring C8-17 for a tapered abrasion tester was pressed onto the pulley @.

In FIG. 1, ■ indicates a driving pulley, ◎ indicates a driven pulley (however, the brake is applied so that a tension of 3 kg is applied to the belt), and O indicates a driven pulley (contact pressure: 100 g).

In this state, a rotation test was conducted for 10 hours at a circumferential speed of 10 m/min, and the elongation and wear of the belt after rotation were observed.

Belt ■ had a diameter of 100.2 mrn and a wear amount of 24 rv.

In the case of the belt ■, the belt stretched (permanently deformed) under a load of 3 kg, caused a slip on the pulley ■, became unable to rotate, and stopped in 2 hours.

In belt ■, the rubber layer on the surface was worn away and the reinforcing fabric was exposed on the surface.

The amount of wear was 347 ~, and the diameter was 100.1 m.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a schematic part of an apparatus for performing stretching according to the present invention. 1: Film or sheet punched into an annular shape by stretching to make a drive belt, or tube or pipe cut into rings, 2, 2-way pulley, 3.3': Rotating shaft of pulley. Fig. 2 is a cross-sectional view of the drive belt wrapped around the pulley and pressed against the wear wheel. ■: Drive pulley, @: Driven pulley, ○: Driven pulley.

Claims (1)

[Claims] 1. A method for producing a seamless drive belt, which comprises cutting an unstretched pipe or tube of a polyester block copolymer into rings and stretching it.