JPH0339819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a wide belt made of thermoplastic resin.

(Prior Art) Conventionally, thermoplastic resin belts have been manufactured by extruding the belt body into a belt-like plate-like body and then performing predetermined endless bonding. Therefore, due to processability problems with extrusion molding, only narrow belts can be manufactured, and in order to manufacture wide belts, multiple narrow plate-shaped bodies (belts) are formed by extrusion molding. After that, the longitudinal edges to be joined are cut diagonally so that they can abut each other, and a hot melt adhesive is placed between the joining surfaces of these edges, or a solvent is applied to the joining surfaces. The method used was to apply a mold adhesive, join the two at room temperature or under heat and pressure, and finally perform endless joining.

(Problems to be Solved by the Invention) However, the above conventional method has the following drawbacks.

In this method, the longitudinal edges of the belt are cut off diagonally so that they can abut each other, and the reason for this is that when the belt is bent and runs on a pulley with a small diameter, stress is generated at the joint interface. This is to prevent concentration from occurring; however, despite such considerations, if the joint surface is not cut smoothly, sufficient adhesion may not be obtained, or the belt may not be exposed to high temperatures. Alternatively, when used in the presence of water or various solvents, the conditions of use are often restricted by the performance of the adhesive sheet or adhesive. Further, according to such a method, it is difficult to obtain flatness between the belt body and the joint part, and furthermore, in the case of joining the belt under heat and pressure, not only is necessary equipment such as a press required, There are problems such as the belt body being thermally deformed by heating and pressurization, resulting in partial wavy phenomena, large errors in belt design dimensions, and the need for on-site joining processing because required equipment such as a press is required. However, there is a problem in that wide belts cannot be manufactured in the factory and must be transported to the site.

The present invention was invented based on the above circumstances, and provides a method for manufacturing a wide belt made of thermoplastic resin, which eliminates the above-mentioned conventional drawbacks and can easily and efficiently manufacture a high-quality wide belt. The purpose is to

(Solution Means) The present invention processes (or extrudes) a plurality of band-shaped plate bodies obtained by extrusion molding a thermoplastic resin, at least the longitudinal edges of the plate bodies to be joined into a specific shape. After forming the plate into such a shape (by molding), using a specific welding rod made of the same resin as the plate, the plates are sequentially welded together in the longitudinal direction to form a belt. It is characterized by forming.

The plate-shaped body that makes up the belt body is made of thermoplastic resin (including copolymer resin) such as polyurethane, polyester, polyamide, polyvinyl chloride, polypropylene, and polyether, and the wall thickness is determined by its bending resistance. It is formed to a thickness of about 0.5 to 5 mm in consideration of filling and softness.

The welding rod for welding is made of the same resin as the belt body, and is formed into a rod-shaped body by extrusion or the like in advance when widening the belt. The vertical cross-sectional shape of the rod-shaped body is approximately the same as the cross-sectional shape of the welding gap formed between the ends of the belts to be joined as described above, and is, for example, triangular or fan-shaped.

Further, it is preferable that the angle of the acute angle portion of the inclined surface formed on the longitudinal edge of the plate-shaped bodies to be joined is in the range of 45 to 60 degrees from the viewpoint of the strength of the joint and the joining efficiency.

Further, the temperature of the hot air blown when welding the plate-shaped body and the welding rod is not particularly limited to the present invention, but usually, considering work efficiency, the temperature is about 2 to 3 times higher than the melting temperature of the resin. twice as high temperature is used.

(Example) In order to manufacture a wide belt made of polyester resin with a width of 1400 mm (thickness 3 mm, length 21 m, resin melting temperature 250°C), a belt-shaped plate made of polyester resin with a width of 700 mm (thickness 3 mm, Two pieces (length 21 m) were molded by extrusion molding.

Next, the longitudinal edges of the plate-shaped bodies to be joined were cut out along the entire length at an inclination angle of 45 degrees in the thickness direction. Thereafter, as shown in FIG.
are arranged facing each other on the same plane, and the plate-like body edge 12,
A gap 20 for welding was formed between 12. Then, as shown in FIG. 2, a polyester resin welding rod 30 formed by extrusion into a sector-shaped cross section (radius 4.5 mm) is inserted into the cavity 20, and at that time, the welding rod 30 and the plate-shaped body are inserted. Hot air (temperature: 600° C.) was blown onto each joining surface of the edge portion 12 to melt the surface layer portions of each in a short period of time, and sequentially welded and integrated them over the entire length. The time required for this work was approximately 30 minutes. At this time, a built-up portion 32 was formed on the surface of the joint portion of the plate-shaped body by the surplus portion of the welding rod 30 that had completely filled the void portion 20 . Next, after cooling the joint, the built-up portion 32 was cut out using a knife or the like, and the cut surface was finished with a press roller to make the surface smooth as shown in FIG. 3 while blowing hot air onto the cut surface. Finally, the belt body obtained as described above was endlessly joined using the same method to obtain the desired wide belt.

The performance of the wide belt manufactured by this example is that the strength of the joint is excellent, the joint has excellent flexibility even when used across pulleys with a small diameter, and the belt does not bend or peel at that part. It did not cause any damage and was highly durable.

On the other hand, belts that are joined with an acute angle of less than 45 degrees on the sloped surfaces formed on the longitudinal edges of the plate-shaped objects to be joined have a large joining area and are inferior in joining efficiency. Belts in which the angle of the acute angle portion of the surfaces exceeds 60 degrees are undesirable because stress concentration tends to act on the joint portion during bending, resulting in poor bending resistance.

(Effect of the invention) According to the manufacturing method of the present invention having the above configuration,
The plate-shaped body constituting the belt body can be formed by extrusion molding, and a welding rod made of the same material as the plate-shaped body is inserted between the longitudinal edges of the plate-shaped bodies to be joined. Since it is possible to weld and integrate in a short time by heating with high-temperature hot air, there is no need for large-scale equipment such as a press for joining, and joining can be performed on-site with a simple hand-held welding jig equipped with a means of blowing hot air. Work can be done easily and efficiently. In addition, since the wide belt obtained by this manufacturing method does not involve heating and pressure bonding using a press or the like as in the past, the belt body may be thermally deformed, resulting in waving in some areas, or Not only will there be no errors in the design dimensions, but the strength of the joint will be equal to that of the belt body because the joint surface is formed uniformly with no interface due to welding. Due to this formation, there is no deterioration in the bending resistance or other mechanical properties of the belt body.

In addition, a welding rod having a cross-sectional area slightly larger than the cross-sectional area of the gap is inserted into the gap formed between the longitudinal edges of the plate-like bodies that will become the joint, and the welding rod is inserted onto the belt surface at the joint. Since the built-up part is once formed by the surplus part of the welding part, even if hot air is blown onto the joint part, a concave part is not formed on the belt surface due to the wind pressure, and the built-up part is finally removed. This makes it possible to manufacture a belt with a flat surface.

Furthermore, according to the joining method of the present invention, not only can wide belts be manufactured, but even if the belt is damaged due to an accident during belt operation, only the damaged part can be pasted using the same method. You can also change it.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams for explaining the present invention, and FIG. 1 is a partial cross-sectional view showing a state in which the longitudinal edges of plate-like bodies to be joined are arranged opposite each other, and FIG. The figure is a partial cross-sectional view showing a state in which plate-like bodies are joined together using a welding rod, and Figure 3 is a partial cross-sectional view showing a state in which the plate-like bodies are joined together and the built-up portion is removed to form a flush belt surface. It is a diagram. DESCRIPTION OF SYMBOLS 10... Plate-shaped body, 12... Longitudinal edge, 14... Acute edge edge line, 20... Gap part, 30... Welding rod,
32...Meat filling part.

Claims (1)

[Claims] 1. After extrusion molding a thermoplastic resin to form a plurality of strip-shaped plate-like bodies, at least the longitudinal edges of the plate-like bodies to be joined are cut diagonally in the thickness direction, and the edges are sloped. Either provide a surface or extrude a thermoplastic resin so as to form the inclined surface in advance at least on the longitudinal edges of the strip-shaped plate-like body to be joined, and then attach each of the edges to be joined. The ridge lines of the acute edges of the plates are brought together to face each other on the same plane, and a welding gap having a triangular cross section is formed between the edges, and then the gap is preformed with the same resin as that of the plate-shaped body. While inserting a welding rod having a cross-sectional area slightly larger than the cross-sectional area of the part into the gap, hot air at a temperature higher than the melting temperature of the resin is applied to each joint surface between the longitudinal edge of the plate and the welding rod. By spraying, we melted the surface layer of each joint surface and welded and integrated them sequentially in the longitudinal direction of the plate-like body, and by using the surplus part of the welding rod that filled the above-mentioned voids on the surface of the plate-like body. 1. A method for producing a wide belt made of thermoplastic resin, which comprises forming a belt by forming a built-up part and then removing the built-up part to form a flat plate surface.