JPS58183240A - Manufacture of endless transmission belt - Google Patents

Abstract

PURPOSE:To manufacture the titled belt having excellent bending-resistant property and durability by molding specific tooth-form concave sections to the lower cloth and compression rubber section of the belt proper through a preparatory molding process. CONSTITUTION:The tooth-form concave section 9a is molded preparatorily by using a drum die 7 of which the relationship of contour length L in case of the molding of the tooth-form concave section 9a and the contour length L' of the convex section 7a of the drum die 7 satisfies L>L' and a formula L/L'=1.02- 1.15 is formed in the lower cloth 1 and compression rubber section 2 of the belt proper X, and a cushion rubber 3a, a tensile body 4, a cushion rubber 3b on the tensile body, a tension section rubber 5, into which short fibers are disposed, and upper cloth 6 are laminated on the compression rubber section 2 of the preparatory shape X' and vulcanized. Accordingly, the generation of the cracks of lower cloth and its progress can be retarded, and a phenomenon of breaking of a rubber of a cog section with the partial fatigue of the tensile body by the progress of cracks can be improved largely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an endless power transmission belt, and more particularly to a method of manufacturing a low-edge cog belt having a substantially V-shaped groove in the middle direction of the inner peripheral surface of the belt.

Conventionally, in this type of belt manufacturing method, a drum mold with tooth-shaped irregularities on the outer circumferential surface is used to sequentially layer each heald component material to form a belt molding, and then undergoes a vulcanization and finishing process. It is intended as a product.

By the way, as for the structure of the conventional belt main body X, as shown in FIG. 1 and FIG. 2(a) to FIG. 2(C), for example, a lower cloth 1. Compression part rubber 2 with short fibers arranged in the direction of the belt
．． Cushion rubber 3a under the tensile body, tensile body 4. Cushion rubber 3b on the tensile body, tension section rubber 5 with short fibers arranged in the same manner as the compression section rubber 2. A type in which upper cloth 6 and upper cloth 6 are sequentially laminated is common. When molding such a belt main body will be implemented sequentially. The unevenness of the tooth shape after pasting the lower cloth 1 is as follows:
After filling, the outer surface is finished to a smooth condition. After molding the compressed rubber portion 2 with a smooth outer surface, other constituent materials are sequentially laminated to form the belt body X.

As a method for filling the recess 9 with rubber, for example, there is a method of embedding a rubber strip, or a method of pasting a compressed portion rubber 2 preformed in a shape that fits into the tooth profile 8 onto the lower fabric 1. .

However, in the final product molded by the conventional manufacturing method as described above, since the lower cloth 1 is pasted on the drum mold 7, stress σ remains in the lower cloth portion at the top of the groove after vulcanization. However, there was a problem in that when the product was put into use, cracks were noticeable from that part.

This invention was devised by focusing on such conventional problems, and its purpose is to improve the bending resistance of an endless power transmission belt by providing a low edge cog belt with grooves on the inner surface of the belt body. The present invention provides a method for manufacturing an endless power transmission belt that improves the durability of the belt by effectively preventing and delaying the occurrence and progression of cracks from the vicinity of the groove tops.

In order to achieve the above object, the present invention molds tooth-shaped recesses in the lower cloth and compressed rubber portion of the belt body in a preforming process, and also adjusts the contour length during molding of the tooth-shaped recesses and vulcanization in the finishing process. Outline length L of the convex part of the drum mold for molding
o The relationship between L and L' is L>L', and the ratio of the contour length of the tooth-shaped concave portion of the belt body to the contour length Lo of the drum mold convex portion for vulcanization molding is L/ L' to 1
．． The gist is to set it within the range of 02 to 1.15.

Hereinafter, the present invention will be described in detail based on FIGS. 3 to 7 of the accompanying drawings. Note that the same components as those in the conventional example are given the same reference numerals, and the description thereof will be omitted.

Figure 3 shows the process of molding a preformed product X' of the heald main body X using a drum trough die 7 for vulcanization. It is molded using a press.

In this invention, a tooth-shaped recess 9a is molded in the lower cloth 1 and compression rubber 2 of the belt main body X as shown in FIG.
When molding a, a toothed flat mold is used such that the contour length of the toothed recess 9a during molding is larger than the contour length Lo of the convex portion 7'a of the drum mold 7.

Therefore, the outline length of the tooth-shaped recess 9a and the outline length Lo of the protrusion 7a of the drum mold 7 are in the relationship L>L'', and when they are fitted together, the tooth-shaped recess 9a is formed as shown in FIG. A space 10 is formed between 9a and the convex portion 7a of the drum mold 7.The thus formed preform X° is molded in the drum mold 7 for vulcanization molding, and other The constituent materials are the cushion rubber 3a under the tension body, the tension body 4, the cushion rubber 3b on the tension body, the tension part rubber 5 on which short fibers are arranged like the compression part rubber 2, and the upper fabric. 6 is sequentially laminated and vulcanized.

In the product vulcanized and molded in this way, the space 10 is filled with the lower fabric 1 and the compressed rubber 2, as shown in FIG. That is, when the space IO is filled with cloth and rubber during vulcanization, the lower cloth 1 located near the top of the tooth groove receives uniform pressure due to expansion during vulcanization from the compressed rubber 2 on the outer periphery.
By being compressed, the internal stress σ shown in FIG. 6 can be made extremely small.

The contour length L is 1.02 to 1 for the contour length Lo described above.
．． The relationship should be 15 times, more preferably L/L'
= 1.05 to 1.15. As a result of an experiment using the test machine shown in Figure 7, as is clear from the table below, the effect is small when L/L° is less than 1.02, and the molding process becomes difficult when it is more than 1.15. It is from.

Table (initial crack occurrence rate of lower fabric part) (%) In Fig. 7, X is the belt body, 11 is the large diameter test sheave, 12 is the small diameter test sheave, and W is the heald body
It is a weight that adds tension to. As described above, the present invention molds tooth-shaped recesses in the lower fabric and compressed rubber portion of the belt body in the preforming process, and also adjusts the contour length during molding of the tooth-shaped recesses and the vulcanization molding in the finishing process. The relationship between the contour length L'' of the drum mold convex part is L>L', and the contour length of the tooth-shaped concave part of the belt body and the drum mold convex part for vulcanization molding are Outline length L
By setting the ratio L/L'' to 1.02 to 1.150, the residual stress after vulcanization of the lower fabric near the top of the belt groove is reduced, thereby preventing the occurrence and progression of cracks in the lower fabric. This has the effect of significantly improving the phenomenon of rubber failure at the cog portion, which is accompanied by local fatigue of the tensile member due to crack progression, to a greater degree than in the past.

[Brief explanation of drawings]

Figure 1 is a half-sectional view of a conventional drum mold, and Figure 2 (a!
) to FIG. 2(c) are cross-sectional explanatory views of a conventional belt body, and FIG. 3 is a preformed product X° of the belt body X of the present invention.
FIG. 4 is a cross-sectional view comparing the contour lengths of the belt body and the drum mold, and FIGS. 5 and 6 are Cross-sectional view when the belt body is fitted into the drum mold and cross-sectional view after vulcanization molding, No. 7
The figure shows a test machine used for experiments of this invention. 1...Lower fabric 2...Compression part rubber 3a, 3b...Cushion rubber 4...Tension body 5...Tension part rubber 6...Upper fabric
7. Drum mold 8.. Tooth shaped recess 9.. Recess 9a.. Tooth shaped recess Agent Patent attorney Ogawa Ya - Kensho Noguchi Shimo Kazuhiko Figure 1 Figure 2 (a) ■ 2nd CA (b) b ,,l Funeral diagram 2 (C) xt
, e X 65i-i Fig. 40 .

Claims (1)

[Claims] 1. In the preforming process, a tooth-shaped recess is molded on the lower cloth and compressed rubber part of the belt body, and the contour length of the tooth-shaped recess during molding and the vulcanization molding in the finishing process are determined. A method for manufacturing an endless power transmission belt, characterized in that the relationship between the contour length L'' of the protrusion of the drum mold and the relationship L>L' is satisfied. 2. The contour length L of the tooth-shaped recess of the heald body and the contour length of the convex part of the drum mold for vulcanization molding, the ratio L/L.
The method of manufacturing an endless power transmission belt according to claim 1, wherein