JPS6042022B2 - Manufacturing method of toothed belt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a polyurethane toothed belt whose toothed surfaces are covered with a reinforcing cloth.

In particular, by accurately attaching the reinforcing cloth to the tooth profile surface of the toothed belt during the belt manufacturing process, it is possible to reliably prevent tooth base cracks that frequently occur in this type of belt and extend the belt life. By increasing the number of belt teeth and forming precise belt teeth, smooth belt drive can be achieved. Traditionally, polyurethane toothed belts have been manufactured by wrapping reinforcing cloth endlessly around the outer circumferential surface of a cylindrical inner mold that has multiple tooth-shaped grooves in the axial direction of the outer circumferential surface, or by wrapping the reinforcing cloth around the inner mold. The rope is wound endlessly along the tooth grooves, and the rope tensile body is spirally wound on top of it.A cylindrical outer mold is then set concentrically on the outside of this inner mold, and the inner mold and Liquid urethane elastomer is injected into the gap between it and the outer mold, and the urethane elastomer is passed between the tensile members and filled into the tooth grooves of the inner mold to form the teeth of the belt, and the tensile member is embedded. The most common method is to simultaneously form the belt tension part using the urethane elastomer, remove the belt molded body from the mold after curing the urethane elastomer, and cut the belt molded body into rounds in the circumferential direction to a predetermined width to obtain multiple toothed belts. However, when winding the rope tensile material or filling the teeth with liquid urethane elastomer, the reinforcing fabric may become misaligned, causing air bubbles to form on the surface of the belt teeth or cracking the teeth. Wrinkles and sagging occurred in the reinforcing cloth on the surface of the belt, and there were many problems in the uniform and accurate forming of the belt tooth profile, which is the most important part for smooth belt drive.

In the present invention, a reinforcing cloth coated with polyurethane elastomer is held between a pair of molding plates, heated and pressed to form a reinforcing cloth with a tooth shape, and then tooth shape connecting pieces are solidified only at both ends of the groove of this reinforcing cloth. A middle cylindrical inner metal part with intervening and interlocking, integrally strengthening the shape retention of both ends of the reinforcing cloth, having tooth-shaped grooves carved in the axial direction of the circumferential surface, and having a thin layer of polyurethane elastomer adhered inside the grooves. The reinforcing cloth with tooth-shaped connecting pieces attached and integrated at both ends is pressed and wound around the mold in an interlocking state, and the lobe tensile material is spirally wound on the surface of the reinforcing cloth, and then the outer mold is assembled concentrically, A method for producing a toothed belt is provided in which a belt molded product produced by injecting liquid urethane elastomer between both molds and curing is cut into rings.

The present invention aims to prevent failures in forming accurate belt tooth portions due to disorder of the reinforcing cloth, and the reinforcing cloth is molded to form a reinforcing cloth with a tooth pattern in advance. A tooth-shaped connecting piece is solidified and interposed only in the groove portions at both ends of the reinforcing cloth to integrally strengthen the shape retention of the portion, and then it is precisely fitted and positioned along the inner mold tooth portion to prevent subsequent injection. The structure is characterized by the fact that the center portion of the remaining reinforcing cloth is also accurately fitted into the tooth-shaped groove of the inner mold by using the pressing force of the liquid polyurethane elastomer.

Next, a method for manufacturing a polyurethane toothed belt according to the present invention will be explained with reference to the drawings.

First, as a first step, as illustrated in FIG. 1, the upper and lower 1
A reinforcing fabric 4 made of stretchable canvas, non-woven fabric, knitted fabric, etc. woven with crimped nylon warp and normal nylon weft is placed between the pair of patterning boards 1 and 2, especially when the reinforcing fabric 4 is stretchable canvas. The stretching direction of the canvas is arranged perpendicular to the tooth profiles 3, 3 of the lower molding board 2.

Apply polyurethane elastomer to the entire surface of the reinforcing cloth 4,
This reinforcing cloth 4 is held between the upper and lower mold attachment plates 1 and 2, and is heated under pressure from the outside for a predetermined period of time, so that the shape-retaining polyurethane elastomer permeated through the reinforcing cloth 4 is cured, and the tooth-shaped reinforcing cloth 4
a is obtained (see Figure 2). The next second step is to remove the tooth-shaped reinforcing cloth 4a. Tooth-shaped connecting pieces are solidified and interposed only at both end portions of the tooth grooves to integrally strengthen and fix both end portions of the reinforcing cloth, thereby achieving further shape retention of the tooth-shaped reinforcing cloth.

As shown in Fig. 3, the upper plate 1 of the molding plate is removed, and both ends of the lower molding plate 2 with the tooth-shaped reinforcing cloth still attached are used as a lower mold by a pair of end plates 6, 6. It is closed by tightening bolts 7 etc. to the lower molding board 2, and one pre-formed tooth-shaped urethane rod 8 as shown in FIG. 4 is placed in the center of each tooth groove of the lower molding board 2. That is, the tooth-shaped reinforcing cloth 4a is fitted into the center of each groove, thereby creating a gap 9 between the end plate 6 and the end face of the fitted tooth-shaped rod-like body 8 (see FIG. 3). Polyurethane elastomer is injected into the void 9, the upper plate 10 is placed on the lower molding plate 2, and the elastomer injected into the void 9 is cured by applying pressure and heat from the outside. , the tooth-shaped urethane rod-shaped body 8 is sequentially removed, and the groove portions at both ends of the tooth-shaped reinforcing cloth shown in FIG. It is removed from the lower molding board 2. As a third step, as shown in FIG. 6, the tooth-shaped reinforcing cloth 4b is placed in a cylindrical inner mold 12 having a large number of tooth-shaped grooves in the axial direction on the entire outer periphery. After spraying a thin layer of polyurethane elastomer to adhere it, the tooth-shaped portions of the reinforcing cloth 4b are made to match the tooth-shaped grooves 13 of the inner mold 12, and the tooth-shaped connecting pieces 5 integrated with the reinforcing cloth 4b are attached to both ends of the reinforcing cloth 4b. . In this invention, a method is adopted in which tooth-shaped connecting pieces 5, 5 integrally attached to both ends of the reinforcing cloth are pushed into the inner mold groove, so that the reinforcing cloth 4b is wrapped around the outer peripheral surface of the inner mold 12. Fixation becomes simple and the fixation becomes strong and reliable. As a fourth step, a low-elongation, high-strength material such as steel wire, Tetron (trade name), nylon fiber, etc. The lobe tension member 15 is wound in a spiral.

Thus, as the fifth step, reinforcing cloth 4 with a tooth shape and a connecting piece is formed.
A cylindrical outer mold (not shown) is set concentrically outside the inner mold with a lobe tensile member wrapped around the outer peripheral surface of b, and both ends of the inner and outer molds are closed with end walls. A liquid urethane elastomer is press-fitted into the gap formed by both the inner and outer molds, and the elastomer fills the gap. While being pressed against the tooth profile groove of the inner mold, accurate shaping of the belt tooth profile is carried out, whereby the tooth part and tension part of the belt are simultaneously filled and molded, and vulcanization hardening progresses by heating for a predetermined time. A wide toothed belt molded body is formed. In the final sixth step, the thus obtained toothed belt molded body is removed using both the inner and outer molds, cut into rounds with a predetermined width in the circumferential direction, and the entire surface of the toothed part shown in FIG. 7 is covered with reinforcing cloth. A precisely coated polyurethane toothed belt 16 is obtained.

The present invention is intended to strengthen the belt tooth portion by accurately covering the entire surface of the tooth portion with reinforcing cloth. Accurately fixing and covering the reinforcing cloth at a predetermined position is often accompanied by difficulties. In the present invention, a reinforcing cloth with a tooth shape is created in advance by applying polyurethane elastomer to the reinforcing cloth and molding using heating and pressure, and then grooves at both ends of this reinforcing cloth are made into urethane tooth shape connecting pieces. In order to further strengthen the shape retention, the reinforcing cloth with the connecting piece is tightly wrapped around the grooved peripheral surface of the inner mold in an interlocking state, and the tooth-shaped connecting piece is centered. Since it can be stably attached to the surface of the inner mold by pressing the reinforcing cloth, it can be used to wrap the lobe tensile material or inject the liquid urethane elastomer into the belt. The fit of the inner mold of the reinforcing cloth with toothed shapes is achieved by the retention of the toothed connecting pieces that are integrally solidified at both ends of the reinforcing cloth. The shape-reinforcing portion is tightly fitted into the tooth groove of the inner mold by effectively utilizing the pressing force during the subsequent injection of liquid urethane elastomer. This simplifies the time-consuming work of press-wrapping the reinforcing cloth onto the inner mold, and the reinforcing cloth is accurately and firmly fixed over the entire surface of the toothed part of the belt. It is possible to maintain a belt with no cracks and a good meshing state for a long period of time.

Brief explanation of the drawings Figure 1 is a partial perspective view of the molding board, Figure 2 is a partial perspective view of the molding board;
The figure is a partial perspective view of the reinforcing cloth with a tooth-shaped pattern, FIG. 3 is a perspective view showing the molding process of the reinforcing cloth with a connecting piece, FIG. 4 is a perspective view of a tooth-shaped urethane rod, and FIG. 5 is a reinforcement with a connecting piece. FIG. 6 is a perspective view of the inner mold in which the reinforcing cloth with connecting pieces is fixed to the peripheral surface, and FIG. 7 is a perspective view of a part of the toothed belt obtained by implementing the present invention. It is a diagram.

In the figure, 1 and 2 are upper and lower molding plates, 3 is tooth profile, 4 is reinforcing cloth,
4a is a reinforcing cloth with a tooth pattern, 4b is a reinforcing cloth with a connecting piece, 5
, 5 is a tooth profile connecting piece, 12 is an inner mold, 13 is a tooth profile groove, 15
indicates a lobe tensile body.

Claims (1)

[Claims] 1. A reinforcing cloth coated with polyurethane elastomer is held between a pair of molding plates, heated and processed to form a reinforcing cloth with a tooth shape, and tooth shape connecting pieces are solidified and interposed only at both ends of the groove of this reinforcing cloth. Then, both ends of the reinforcing cloth are integrally strengthened to retain their shape, tooth-shaped grooves are carved in the axial direction of the circumferential surface, and tooth-shaped grooves are formed around a cylindrical inner mold in which a thin layer of polyurethane elastomer is adhered in the grooves. The reinforcing fabric with connecting pieces attached and integrated at both ends is pressed and wound in an interlocking state, and the rope tensile body is spirally wound on the surface of the reinforcing fabric. After that, outer molds are assembled concentrically, and a A method for manufacturing a toothed belt in which a belt molded product is injected into liquid urethane elastomer, cured, and torn, and then cut into rings.