JPH0553977B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a toothed belt in which a plurality of tooth surfaces formed at a constant pitch in the longitudinal direction are covered with a reinforcing canvas layer. be.

(Prior art) Conventional toothed belts, especially standard trapezoidal toothed belts, have insufficient tooth strength compared to the belt strength. Most of the lifespan is due to tooth breakage, and damage to the tensile member, ie, the belt itself, is extremely rare, which is a cause of shortening the lifespan.

In view of this, the means to improve the strength of the teeth are to improve the shear fatigue strength by increasing the rigidity of the teeth, and to improve the wear resistance of the teeth to reduce tooth wear. Possible ways to improve fatigue resistance include improving the tooth shape in the tooth portion to distribute and make stress uniform, preventing stress concentration, and improving fatigue resistance.

However, in the above case, since the teeth are formed of an elastic body, even if the shape of the teeth is specified, the shape changes depending on the load, making it difficult to obtain a sufficient improvement effect.

Therefore, focusing on the above points, conventional techniques have been developed to improve the wear resistance of the teeth and increase the strength of the teeth.
As shown in Japanese Patent Publication No. 48-41176, a toothed belt using a wear-resistant canvas having self-lubricating properties, that is, a lubricant such as graphite is added to the woven grooves on the tooth side surface of the canvas. A toothed belt using canvas filled with a rubber mixture is described.
With this toothed belt, when the canvas is subjected to friction due to contact with the pulley while running, a lubricant such as graphite, which is rubbed into the woven grooves of the canvas along with rubber, is supplied to the contact surface, causing friction on the contact surface. The action of keeping the coefficient at a low level prevents the canvas from wearing out.

By the way, although the above-mentioned toothed belt has a structure that improves the wear resistance of the teeth, it does not have the effect of improving the rigidity of the teeth.
In particular, when graphite is used as a lubricant, its high-temperature stability decreases;
In the above), the lubricating effect is slightly reduced, and there is a problem that the effect of improving wear resistance cannot be sufficiently obtained. moreover,
Since canvas is required to have a large number of weave structures,
The weaving structure is limited and the canvas that can be used is limited. Furthermore, since rubber glue containing a lubricant is rubbed into the canvas in advance, the stretch of the canvas is suppressed, making it unsuitable for molding by press-fitting.

Therefore, in order to improve the abrasion resistance of the tooth part and the rigidity of the tooth part to improve the strength of the tooth part and improve the durability of the belt,
Reinforced adhesive rubber in which wear-resistant reinforcing material with high hardness or high elasticity is mixed on the inner and outer surfaces of the reinforcing canvas layer that covers the tooth surfaces of the teeth, and reinforcing material is mixed on the inner surface of the reinforcing canvas layer. developed a toothed belt with
(See Publication No. 65644).

(Problem to be Solved by the Invention) However, although the above technology has a sufficient effect on improving the durability of the belt, wear-resistant reinforcing materials are generally expensive and the number of manufacturing steps increases, resulting in increased costs. There is the problem of inviting

On the other hand, Japanese Patent Publication No. 57-28813 discloses an elastomer-impermeable outer surface of a wear-resistant fabric layer that is closely fitted along alternating tooth and land portions and forms a surface cover for these portions. It is described that the elastomer-impermeable material has a coefficient of friction significantly lower than that of the elastomer used.

However, in the above technology, although the elastomer impermeable layer exhibits a lubricating effect, this impermeable layer is intended to prevent urethane, which has a high coefficient of friction, from seeping onto the outer surface of the canvas, and disappears at the beginning of running. The effect cannot be expected to be maintained. Moreover, since the elastomer impermeable layer is bonded to the canvas in advance, the canvas does not stretch and stretches along the grooves of the mold.
It is necessary to mold each piece one by one and fit the canvas along the mold, which poses a problem of inefficiency and increased costs.

The present invention has been made in view of these points, and its objectives are to improve the wear resistance of the tooth portion, improve strength by reducing tooth wear, and further improve the rigidity of the tooth portion. The object of the present invention is to easily obtain a toothed belt with greatly improved durability.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for manufacturing a toothed belt in which a plurality of tooth surfaces formed at a constant pitch in the longitudinal direction are covered with a reinforcing canvas layer. The following solutions were taken to solve the problem.

That is, the first solution of the present invention is as follows:
A non-bonded canvas fabric formed in accordance with the circumferential length of the mold is attached to a mold in which a plurality of concave grooves for forming tooth portions extending in the mold axis direction are formed at a constant pitch on the outer peripheral surface of the mold. Next, at least one layer of a thermoplastic resin sheet having a melting point of 180° C. or lower, an adhesive-treated tensile material, and an unvulcanized rubber sheet are sequentially wrapped around the outside of the canvas. Thereafter, a sleeve is fitted over the wound body and pressure vulcanized to form a cylindrical molded body. Thereafter, the molded body is removed from the mold and cut at predetermined pitches in the axial direction of the molded body, so that the thermoplastic resin constituting the thermoplastic resin sheet forms a bonding surface with the tooth surface of the tooth part on the canvas. The present invention is characterized in that a toothed belt is obtained in which the tooth surfaces of a plurality of tooth portions are covered with a reinforcing canvas layer impregnated over the outer surface thereof.

The second solution of the present invention is that in the above case, a lubricant made of molybdenum, graphite, metal powder, fluorine fiber, carbon fiber, aramid fiber, etc. is added to the thermoplastic resin constituting the thermoplastic resin sheet. It is characterized by containing 10 to 50% by weight.

(Function) With the above configuration, in the first solving means of the present invention, the thermoplastic resin sheet is softened and melted by pressure vulcanization, and the thermoplastic resin flows into the weave of the canvas. A toothed belt is obtained in which a plurality of tooth surfaces of the tooth portions are covered with a reinforcing canvas layer formed by impregnating the canvas from the joint surface with the tooth surface of the tooth portion to the outer surface thereof.

From this, when the toothed belt comes into contact with the pulleys and undergoes a certain degree of wear and tear while the belt is running, the thermoplastic resin impregnated in the canvas is melted by the heat of the belt running, and the reinforcing canvas layer is It oozes out onto the contact surface of the toothed part with the pulley, and wear of the toothed part is greatly suppressed.

Furthermore, the reinforcing canvas layer improves the rigidity of the teeth as a composite, and also reduces deformation during meshing with the pulley, improving shear fatigue strength and improving durability.

In the second solution of the present invention, when the belt runs, the lubricant mixed in the thermoplastic resin oozes out from the reinforcing canvas layer together with the molten thermoplastic resin onto the contact surface of the toothed part with the pulley. Wear is further suppressed.

(Example) Examples of the present invention will be described below with reference to the drawings.

Before explaining the method of the present invention, the structure of a toothed belt 1 having a standard trapezoidal tooth profile 1a obtained by the method of the present invention will be explained based on FIG. The tensile material is made of a material with a high elastic modulus such as glass fiber or steel wire. 3 is an upper rubber layer; 4 is a toothed rubber layer constituting the toothed portion 1a; the upper rubber layer 3 and the toothed rubber layer 4 are made of a material such as chloroprene rubber that protects the tensile member 2 and forms the belt shape; Molded from elastic material. 5 is a reinforcing canvas layer, and as shown in FIG. 2, the reinforcing canvas layer 5 is made of threads (warps and wefts) 5a, 5a, . It is constructed by impregnating an unbonded canvas 14 woven with a thermoplastic resin 6.

FIG. 2 shows a state in which the thermoplastic resin 6 is in contact with the toothed rubber layer 4 and exists within the weave of the canvas 14, and the reinforcing canvas layer 5 has a bonding surface 5b with the toothed surface of the toothed portion 1a. A thermoplastic resin 6 is uniformly impregnated over the outer surface 5c.

As the thermoplastic resin 6, a synthetic resin having a melting point of 180°C or lower, such as polyethylene (melting point 137°C), polypropylene (melting point 176°C), copolymerized or modified nylon, is appropriately employed depending on the purpose. Furthermore, in order to improve the lubricity, the thermoplastic resin 6 contains lubricants such as graphite, molybdenum, carbon, metal powder, fluorine fibers, carbon fibers, aramid fibers, and ultra-hard metals in the form of short fibers. Or use it by mixing it into particles. When using short fibers, the filament diameter is 1
~10μm, aspect ratio (length/diameter) 3~15
When a particle size is used, it is desirable that the particle size is 5 to 50 μm.
In addition, regardless of the shape, the mixing ratio with respect to the thermoplastic resin 6 needs to be within the range of 10 to 50% by weight.

Further, the thermoplastic resin 6 has adhesive properties to the elastic material of the toothed rubber layer 4 and the canvas 14 of the reinforcing canvas layer 5, and is present between the toothed rubber layer 4 and the canvas 14. However, in order to improve the adhesion with them, for example, resin formalin condensed low polymer resin or blocked isocyanate (for example, Hylene Mp, manufactured by Dupont) is kneaded into the thermoplastic resin 6, or belt molding is performed. A PEL adhesive or an isocyanate adhesive may be applied to the surface of the previous lubricating synthetic resin sheet.

Note that the thermoplastic resin 6 present on the surface of the reinforcing canvas layer 5 completely or partially covers the entire surface, but from the viewpoint of improving abrasion resistance, it is preferable to cover the entire surface. It is desirable to do so.

Next, a manufacturing procedure for the toothed belt 1 constructed as described above will be explained based on FIG. 3.

First, an unbonded canvas 14 that is stretchable in one direction is made to correspond to the circumference of a mold 11 in which a plurality of concave grooves 11a for forming tooth portions extending in the direction of the mold axis are formed at a constant pitch on the outer peripheral surface of the mold. The mold 1 is finished into a cylindrical shape.
The canvas 14 is attached to the mold 11 by inserting it into the outside of the mold 11 or by wrapping the canvas 14 around the outer peripheral surface of the mold 11 and fixing both ends of the canvas 14 with an adhesive or the like.

Next, at least one layer of a thermoplastic resin sheet (for example, a polyethylene sheet) 13, which is thinner than the canvas 14 and has a melting point of 180° C. or lower, is then wrapped around it, and its ends are heat-sealed. At this time, the thermoplastic resin 6 constituting the thermoplastic resin sheet 13 is made of short fibers or particles made of graphite, molybdenum, carbon, metal powder, fluorine fiber, carbon fiber, aramid fiber, ultrahard metal, etc. Contains 10 to 50% by weight of lubricant.

Furthermore, one or two tensile members 2 made of glass fiber, steel wire, aromatic polyamide, etc. and subjected to an adhesive treatment are spirally wound thereon. The winding pitch is 1.1 of the cord diameter.
~2.0 times denser pitch is adopted.

Furthermore, one or two layers of unvulcanized rubber sheets 12, which will constitute the tooth rubber layer 4 and the upper rubber layer 3, are wound around the tensile member 2.

Thereafter, a vulcanizing sleeve (not shown) is fitted on the outside of this wound body, and a cylindrical molded body is formed by pressure vulcanization under predetermined conditions using a well-known vulcanizing can.

Thereafter, this molded body is pulled out from the mold 11, demolded, and cut at a predetermined pitch in the axial direction, so that the thermoplastic resin 6 constituting the thermoplastic resin sheet 13 forms the teeth of the canvas 14 in the toothed portions 1a. To obtain a toothed belt 1 in which the tooth surfaces of a plurality of tooth parts 1a are covered with a reinforcing canvas layer 5 impregnated from a joint surface 5b with a surface to an outer surface 5c.

In addition, in the above vulcanization treatment, Fig. 3 a to d
It is thought that the situation shown in is occurring. That is, as shown in FIG. 3a, the tooth forming concave groove 11
When the belt component material is wrapped around the outer circumferential surface of the mold 11 having the mold 11 and is vulcanized under pressure, the unvulcanized rubber sheet 12 is softened and melted, and the thermoplastic resin 6 constituting it is vulcanized. The thermoplastic resin sheet 13 and the canvas 14, which have already been softened and melted, are pushed toward the mold 11 side by the pressure and moved from the gap between the spiral tensile members 2, into the concave groove 11a for molding the teeth of the mold 11. (see Figure 3b).

As the process progresses further, the canvas 14 takes on a shape that follows the concave grooves 11a for forming the tooth portion (see Fig. 3c), and the thermoplastic resin sheet 13 is cured at a vulcanization temperature of 140 to 160°C.
Since it is softened and melted in a flowable state, it is pushed by the unvulcanized rubber sheet 12 and flows into the weave of the warp 5a and weft 5a of the canvas 14.
(See Figure 3d). Thereafter, the canvas 14 is stretched by 30 to 50% relative to its original state, so that it not only fills the weave but also covers the outer surface of the canvas 14 in some cases.

In this way, after the formation of the tooth shape is completed, vulcanization of the rubber of the unvulcanized rubber sheet 12 begins, and a plurality of tooth portions 1a formed at a constant pitch in the longitudinal direction are formed.
A toothed belt 1 whose tooth surfaces are covered with a reinforcing canvas layer 5 is obtained (see FIG. 1).

Therefore, the thermoplastic resin sheet 13 needs to soften and melt at the vulcanization temperature, and this molten thermoplastic resin 6 needs to flow into the weave of the canvas 14 under the vulcanization pressure, so the melting point is low as described above. 180℃
It is desirable to use the following thermoplastic resin 6.

Furthermore, depending on the vulcanization conditions and the amount of thermoplastic resin 6 used, if the rubber constituting the toothed rubber portion 4 flows into the reinforcing canvas layer 5 as shown in FIG. 4a, as shown in FIG. 4b. As shown in FIG. When covering the outer surface 5c of the canvas layer 5, as shown in FIG. If
As shown in FIG. 4e, there are cases where the thermoplastic resin sheet 6 exists inward from the joint surface 5b of the reinforcing canvas layer 5 with the tooth surface 1a of the reinforcing canvas layer 5 and covers the outer surface 5c. However, the same effect is achieved in either case.

Therefore, in the above embodiment, the reinforcing canvas layer 5 covering the tooth surface of the toothed portion 1a of the toothed belt 1 protects the toothed portion 1a from being worn out due to sliding contact with the pulley or interference in meshing. In particular, when 6-6 nylon is used as the material of the canvas 14, it has a somewhat lubricating effect. In addition, since the canvas 14 of the reinforcing canvas layer 5 is impregnated with the thermoplastic resin 6, when the toothed belt 1 comes into contact with the pulleys and undergoes a certain degree of wear and tear, the belt will absorb heat during running. Therefore, the thermoplastic resin 6 melts and the reinforcing canvas layer 5 is formed.
This oozes out onto the contact surface of the toothed portion 1a with the pulley, and wear on the tooth surface of the toothed portion 1a can be significantly suppressed.

Further, in the above embodiment, the stiffness of the toothed portion 1a as a composite body is improved by the reinforcing canvas layer 5, and when the toothed portion 1a meshes with the pulley, deformation due to bending and shearing received from the pulley can be reduced. It is possible to improve shear fatigue strength and durability.

Furthermore, in the above embodiment, the toothed belt can be easily molded using a normal molding procedure without using any special molding equipment.

Next, test results that confirmed the effects of the present invention will be explained.

Test 1 The toothed belt of the present invention and the conventional toothed belt were tested. Belt tooth profile, pitch: ZA type, 9.525 mm Belt width, number of teeth: 19.0 mm, 95 teeth Ambient temperature: 80°C Driven shaft load power: Figure 5 shows the comparative results of a tooth canvas friction test conducted under the test conditions of 2.5ps, drive shaft rotation speed: 6000rpm, and belt initial tension: 25kgf. The conventional type refers to one in which the reinforcing canvas layer is not impregnated with thermoplastic resin.
Inventive type 1 is a reinforced canvas layer impregnated with polyethylene as a thermoplastic resin, and inventive type 2 is a reinforced canvas layer impregnated with polyethylene as a thermoplastic resin.
This is a polyethylene reinforced canvas layer impregnated with 20% by weight of graphite. In addition, the belt tooth surface canvas wear residual rate refers to the ratio of the tooth surface canvas thickness after the belt runs to the tooth surface canvas thickness before the belt runs, and the canvas thickness is measured using an industrial microscope. be.

As is clear from FIG. 5, the toothed belts of Types 1 and 2 of the present invention have four to six times higher wear resistance than the conventional toothed belt.

In addition, for example, in a toothed belt manufactured using a sheet made of polyethylene mixed with 2% by weight of resorcinol-formalin resin in order to further improve the adhesiveness of the thermoplastic resin, there is almost no effect on the residual rate of wear on the belt tooth surface. Without giving, the adhesive force is approx.
It has been confirmed that the improvement is about 20%.

Test 2 Figure 6 shows the results of a comparative test regarding the shear fatigue strength of the toothed belt, in which a load durability test was conducted on the toothed belt under the same running conditions as the toothed canvas wear test, with the load power varied. It shows. Note that the durability life is the running time until the teeth of the toothed belt are damaged by shearing.

As is clear from FIG. 6, the durable life of the toothed belt of the present invention type (invention type 1 in the test) is 1.5 to 2.0 times longer than that of the conventional toothed belt.

In the above embodiment, a toothed belt having a standard trapezoidal tooth profile has been described, but it goes without saying that the present invention can also be applied to a toothed belt having an arcuate tooth profile.

(Effects of the Invention) As explained above, according to the method of the present invention, since the canvas of the reinforcing canvas layer is impregnated with a thermoplastic resin having a melting point of 180°C or less, the wear resistance of the tooth portion is improved. It is possible to easily manufacture a toothed belt whose strength is improved by reducing wear of the tooth portions, and the rigidity of the tooth portions is further improved, thereby greatly improving durability. Furthermore, if a lubricant is mixed into the thermoplastic resin, the wear of the teeth can be further suppressed due to the synergistic effect with the thermoplastic resin.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a longitudinal cross-sectional view of a toothed belt, FIG. 2 is an enlarged view of section A in FIG. 1, and FIGS. figure,
Figures 4 a to e are cross-sectional views showing the state of the thermoplastic resin in the reinforcing canvas layer, Figure 5 is a graph showing the results of the tooth canvas wear test, and Figure 6 is a graph showing the results of the tooth shear fatigue test. It is. DESCRIPTION OF SYMBOLS 1... Toothed belt, 1a... Teeth, 2... Tensile body, 5... Reinforced canvas layer, 5b... Joint surface, 5c...
...Outer surface, 6...Thermoplastic resin, 11...Mold,
11a... Concave groove for tooth molding, 12... Unvulcanized rubber sheet, 13... Thermoplastic resin sheet, 14...
...Canvas.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a toothed belt in which the tooth surfaces of a plurality of teeth formed at a constant pitch in the longitudinal direction are covered with a reinforcing canvas layer, the method comprising forming a plurality of teeth extending in the axial direction of the mold. A non-adhesive treated canvas formed in accordance with the circumference of the mold is attached to a mold in which concave grooves are formed at a constant pitch on the outer circumferential surface of the mold, and then at least one layer of melting point or higher is applied to the outside of the canvas. A thermoplastic resin sheet with a temperature of 180°C or less, an adhesive-treated tensile material, and an unvulcanized rubber sheet are sequentially wrapped around each other, and then a sleeve is fitted around the wrapped body and pressure vulcanized to create a cylindrical shape. The molded body is molded, and then the molded body is removed from the mold and cut at a predetermined pitch in the axial direction of the molded body, so that the thermoplastic resin constituting the thermoplastic resin sheet is formed into teeth on the canvas. A method for producing a toothed belt, the method comprising obtaining a toothed belt in which a plurality of tooth surfaces of the tooth portion are covered with a reinforcing canvas layer impregnated from the joint surface with the tooth surface to the outer surface. 2. The thermoplastic resin constituting the thermoplastic resin sheet contains 10 to 50% by weight of a lubricant made of molybdenum, graphite, metal powder, fluorine fiber, carbon fiber, aramid fiber, etc. A method for manufacturing a toothed belt according to claim 1.