JP2004066709A - Transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission belt capable of suppressing turbulence of rotational transmission between pulleys and preventing noises caused by vibration from occurring. <P>SOLUTION: A mold 5 is covered with a canvas jacket 4a and a core wire 3 is wound on the outside. In addition, an unvulcanized rubber sheet 6 is wound thereon and both end parts 7 thereof are piled up. Tapered parts 9a and 9b are formed in advance on the end parts 7 of the unvulcanized rubber sheet 6. The thickness of a lap part 8 made by piling up the both end parts 7 becomes approximately the same as the thickness of other sites. When this is covered with a shell bag and vulcanization molding is performed in a vulcanization oven, an amount of the unvulcanized rubber of the lap part 8 flowing in the width direction and in the peripheral direction is decreased. A positional shift of the wire 3 due to flow of the unvulcanized rubber hardly occurs. Turbulence of rotational transmission between a drive pulley and a driven pulley can be suppressed so that noises due to vibration of the transmission belt can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission belt such as a toothed belt or a ribbed belt used by being wound around a pulley.
[0002]
[Prior art]
In general, a transmission belt such as a toothed belt or a ribbed belt used by being wound around a pulley is buried in an annular belt body made of rubber so that a core wire for receiving a tensile force is continuous in a circumferential direction of the belt body. It becomes. Among these transmission belts, the toothed belt has a structure in which the belt teeth of the belt main body are covered with canvas, and the cords are embedded so as to be located near the tooth bottom.
[0003]
As a method of manufacturing a toothed belt, first, as shown in FIG. 12A, a canvas is formed by sewing a fabric in an annular shape on an outer peripheral surface of a mold 102 in which tooth grooves 101 corresponding to belt teeth are formed. The jacket 103 is put on, the core wire 104 and the unvulcanized rubber sheet 105 are wound around the jacket 103 in this order, and both ends 106 of the unvulcanized rubber sheet 105 are overlapped. At this time, in the unvulcanized rubber sheet 105, the thickness of the wrap portion 107 formed by overlapping the both end portions 106 is larger than the thickness of other portions.
[0004]
Next, a part of the unvulcanized rubber sheet 105 is caused to flow into the tooth groove 101 of the mold 102 by placing a cylindrical shell bag on the outside of the unvulcanized rubber sheet 105 and heating and pressurizing the shell bag in the vulcanizing pot. Meanwhile, the unvulcanized rubber sheet 105 is vulcanized and formed on the belt body 108 to form a toothed belt (a toothed belt slab). The toothed belt (toothed belt slab) is removed from the shell bag and the mold 101, and the back surface is polished, printed, and cut to a predetermined width to complete the manufacture of the toothed belt. Here, as shown in FIG. 12B, the unvulcanized rubber flows in the width direction and the circumferential direction of the wrap portion 107 by applying heat and pressure from the shell bag side during vulcanization molding.
[0005]
The ribbed belt has a structure in which, for example, an adhesive rubber is interposed between a rib rubber and a canvas covering the outer peripheral side thereof, and a core wire is embedded between the rib rubber and the adhesive rubber. As a method for manufacturing this ribbed belt, a metal jacket is covered with a canvas jacket formed by circularly sewing a canvas in which an adhesive rubber sheet is stuck on the outer peripheral side, and a core wire and an unvulcanized rubber sheet are wound around the outside in this order. Then, the both ends of the unvulcanized rubber sheet are overlapped.
[0006]
Next, the unvulcanized rubber sheet is vulcanized and molded by placing a cylindrical shell bag on the outside of the unvulcanized rubber sheet and applying heat and pressure in a vulcanizing pot to form a rubber body (flat belt). After removing this rubber body from the shell bag and the mold and cutting it to a predetermined width, the ribs are formed on the vulcanized rubber by grinding or the like and turned over to complete the production of the ribbed belt. Similarly to the toothed belt, the unvulcanized rubber sheet is heated and pressurized from the shell bag side during vulcanization molding, so that the unvulcanized rubber flows in the width direction and the circumferential direction.
[0007]
[Problems to be solved by the invention]
However, in the above-described transmission belt, when the unvulcanized rubber sheet is vulcanized and formed, the unvulcanized rubber in the wrap portion flows in the width direction and the circumferential direction. Wire misalignment and deformation of the cord in the thickness direction of the transmission belt are likely to occur. This displacement or deformation of the core wire may cause disturbance in the transmission of rotation between the pulleys by the transmission belt, and there is a concern that noise due to the vibration in the thickness direction of the transmission belt accompanying this may occur.
[0008]
An object of the present invention is to provide a power transmission belt capable of suppressing disturbance in rotation transmission between pulleys and preventing noise due to vibration of the power transmission belt by making it hard to cause displacement or deformation of a core wire. Aim.
[0009]
[Means for Solving the Problems]
In view of the above problems, the present invention includes a belt body formed by laminating both ends of an unvulcanized rubber sheet and vulcanizing and forming an annular shape, and a core wire continuously embedded in the belt body in the circumferential direction. The present invention is to provide a power transmission belt capable of suppressing displacement and deformation of a core wire during vulcanization molding and suppressing disturbance in rotation transmission between pulleys, on the premise of the above structure. In addition, the belt body is not only vulcanized and molded annularly by overlapping both ends of one unvulcanized rubber sheet, but also by annularly laminating the ends of a plurality of unvulcanized rubber sheets. It may be formed by sulfur molding.
[0010]
At the end of the unvulcanized rubber sheet, a tapered portion is formed to make the leading end thinner, and the tapered surfaces of the tapered portions at both ends of the sheet are overlapped to make the thickness of the wrap substantially equal to the thickness of other portions. Then, when the unvulcanized rubber sheet is vulcanized and formed, the amount of unvulcanized rubber in the wrap portion flowing in the width direction and the circumferential direction can be reduced, so that the core accompanying the flow of the unvulcanized rubber can be reduced. Line displacement and deformation can be prevented.
[0011]
The taper portions at both ends of the sheet may have an inclination angle of 15 ° to 70 ° with respect to the circumferential direction of the tapered surface. If the angle of inclination of the tapered surface is smaller than 15 °, it is difficult to form a tapered portion on the unvulcanized rubber sheet. If the angle of inclination of the tapered surface is larger than 70 °, bonding at the lap portion is difficult. The area of the surface is reduced, and cracks due to rubber shrinkage or the like are likely to occur in the wrap portion.
[0012]
If the tip of the tapered portion overlaps the center in the circumferential direction from the other tapered portion, the area of the joining surface of the lap portion can be increased accordingly, and the crack of the lap portion due to rubber shrinkage etc. is more generated Can be difficult. Here, if the length of the overlap in the circumferential direction is 10 mm or less, the thickness of the overlapped portion of the tapered portion can be reduced, and the thickness of the overlap portion can be made substantially equal to the thickness of other portions. it can.
[0013]
Examples of the transmission belt include a toothed belt and a ribbed belt, and the present invention provides a method for manufacturing these belts. Among them, as a method of manufacturing a toothed belt, first, an annular canvas jacket is put on an outer peripheral surface of a mold in which tooth grooves (arc-shaped tooth grooves, trapezoidal tooth grooves, etc.) corresponding to belt teeth are formed, A core wire is wound around the outside, then an unvulcanized rubber sheet is wound around the outside, and both ends of the unvulcanized rubber sheet are overlapped.
[0014]
Furthermore, by covering the outside with a cylindrical shell bag and heating and pressurizing in a vulcanizing pot, a part of the unvulcanized rubber sheet is caused to flow into the tooth space of the mold, and the unvulcanized rubber sheet is removed. A toothed belt (toothed belt slab) is formed by vulcanizing and coating the belt teeth of the belt body in which the cords are embedded with canvas. Thereafter, the toothed belt (toothed belt slab) is removed from the shell bag and the mold, and the back surface is polished, printed, and cut to a predetermined width.
[0015]
In advance, tapered portions are formed at both ends of the unvulcanized rubber sheet to reduce the thickness of the leading end side, and the tapered surfaces of the tapered portions at both ends of the sheet are overlapped and vulcanized and formed. By doing so, the thickness of the wrap portion of the unvulcanized rubber sheet becomes substantially equal to the thickness at other portions, and the amount of unvulcanized rubber of the wrap portion flowing in the width direction and the circumferential direction at the time of vulcanization molding is reduced, It is possible to prevent the displacement and deformation of the cord due to the flow of the unvulcanized rubber.
[0016]
In the method for manufacturing a ribbed belt provided by the present invention, first, an annular canvas is put on the outer peripheral surface of a mold, an adhesive rubber sheet is arranged on the outer peripheral side, and a core wire is wound around the outer side. Here, the adhesive rubber sheet may be wound around the outer periphery of the annular canvas covered by the mold, but in advance, a canvas jacket in which the adhesive rubber sheet is arranged on the outer periphery of the annular canvas is configured. Alternatively, the canvas jacket may be put on a mold. Alternatively, another adhesive rubber sheet may be wound around the core wire, and an unvulcanized rubber sheet may be wound around the outside.
[0017]
Next, an unvulcanized rubber sheet is wound around the outside, and both ends of the unvulcanized rubber sheet are overlapped. Furthermore, the outer shell is covered with a tubular shell bag and heated and pressurized in a vulcanizing kettle to vulcanize and form an unvulcanized rubber sheet, and the inner peripheral surface of the belt body in which the cords are embedded is canvased. To form a rubber body (flat belt) covered with. The rubber body is removed from the shell bag and the mold, cut into a predetermined width as necessary, and a rib is formed on the outer peripheral surface of the belt body by polishing or the like, and the rib is turned over to obtain a ribbed belt.
[0018]
In advance, tapered portions are formed at both ends of the unvulcanized rubber sheet to make the leading end thinner, and the tapered surfaces of the tapered portions at both ends of the sheet are overlapped and vulcanized and formed. Then, the thickness of the wrap portion of the unvulcanized rubber sheet becomes substantially equal to the thickness of the other portions, and the amount of the unvulcanized rubber in the wrap portion flowing in the width direction and the circumferential direction is reduced. The displacement and deformation of the cord due to the flow of the wire can be prevented.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a transmission belt according to the present invention will be described with reference to the drawings. First, the toothed belt of the transmission belt will be described. FIG. 1 is a perspective view of a main part of a toothed belt (power transmission belt) of the present invention. This toothed belt is used by being wound around a toothed pulley, and belt teeth 2 formed on the inner peripheral surface of an annular belt body 1 mesh with the pulley teeth to follow the rotation of the driving pulley. It is designed to transmit to the pulley.
[0020]
The belt main body 1 is made of, for example, rubber made of chloroprene rubber or the like, and has a core wire 3 embedded so as to be located near the bottom of the belt teeth 2. The core wire 3 is a glass core wire or the like obtained by twisting glass fibers, and is continuous in the circumferential direction of the belt main body 1 so as to bear a tensile force acting on the toothed belt. The surface of the belt teeth 2 is covered with a canvas 4 made of, for example, a nylon cloth immersed in rubber glue or the like, and the canvas 4 reinforces the belt teeth 2.
[0021]
Here, the distance (PLD) from the tooth bottom to the center of the core wire 3 is expressed by PLD = t + d / 2 using the tooth bottom fabric thickness (t) and the cord diameter (diameter of the core wire 3, d). This is one of the criteria for determining the size of the toothed pulley that meshes with the toothed belt.
[0022]
Next, a method for manufacturing the toothed belt will be described. FIG. 2A is a perspective view of a main part showing a state in which an unvulcanized rubber sheet is wound around a mold without overlapping a tip end of a tapered portion, and FIG. 2B is an enlarged sectional view of the wrap portion. .
[0023]
As shown in FIG. 2, first, the outer periphery of the mold 5 is covered with a canvas jacket 4 a formed by sewing the canvas 4 in an annular shape, and the core wire 3 is spirally wound around the outside thereof. Next, an unvulcanized rubber sheet 6 is wound around the outside, and both ends 7 of the unvulcanized rubber sheet 6 are overlapped to form a wrap portion 8.
[0024]
The unvulcanized rubber sheet 6 is formed with tapered portions 9a and 9b which are thinned at both ends 7 in advance at the both ends 7 thereof so that the wrap portion 8 is continuous in a direction (width direction) orthogonal to the circumferential direction. deep. Of the two tapered portions 9a and 9b, one of the tapered portions 9a has a tapered surface formed on the outer peripheral side thereof, and the other tapered portion 9b has a tapered surface formed on the inner peripheral side thereof.
[0025]
The two tapered surfaces are set to have the same inclination angle (θ) with respect to the circumferential direction in the range of 15 ° to 70 °, and by overlapping these tapered surfaces, the thickness of the wrap portion 8 is reduced to the other portions. Make it almost equal to the thickness.
[0026]
Thereafter, the unvulcanized rubber sheet 6 is vulcanized and molded by, for example, covering the outside of the unvulcanized rubber sheet 6 with a cylindrical shell bag 10 made of rubber and applying heat and pressure in a vulcanizing pot. At this time, a part of the unvulcanized rubber sheet 6 passes through the gap between the core wires 3 and flows into the tooth grooves 11 of the mold 5 corresponding to the belt teeth 2, and the lap portions 8 thereof are joined. It is formed on the annular belt body 1. The belt main body 1 constitutes a rubber toothed belt slab in which the belt teeth 2 are covered with canvas, and a core wire 3 is buried near the tooth bottom. This is detached from the shell bag 10 and the mold 5 and subjected to back grinding, printing and cutting to a predetermined width, thereby completing the production of the toothed belt.
[0027]
Further, as another method of manufacturing the toothed belt, the tip of the tapered portion may overlap the center of the other tapered portion in the circumferential direction. FIG. 3A is a perspective view of a main part showing a state where an unvulcanized rubber sheet is wound around a mold with the tip of a tapered portion overlapped, and FIG. 3B is an enlarged sectional view of the wrapped portion.
[0028]
This manufacturing method is almost the same as the above-described manufacturing method, except that the tips of the tapered portions 9a, 9b at both ends of the sheet overlap the center in the circumferential direction with respect to the other tapered portions 9b, 9a. As a result, the bonding area of the wrap portion 8 is increased, so that the wrap portion 8 is less likely to crack due to rubber contraction or the like. The length (L) of the overlap in the circumferential direction is set to 10 mm or less so that the thickness of the wrap portion 8 is substantially equal to the thickness of other portions. The other configuration is the same as the above-described manufacturing method.
[0029]
Next, the state of the unvulcanized rubber sheet 6, the core wire 3, and the canvas 4 when the unvulcanized rubber sheet 6 wound around the mold 5 is vulcanized and formed on the belt body 1 will be described. 4 shows a case where the tip of the tapered portion is not overlapped, FIG. 6 shows a case where the tip of the tapered portion is overlapped, and FIG. 6 (a) shows a state before vulcanization molding. (B) shows the state after vulcanization molding.
[0030]
In the case of the conventional manufacturing method, as shown in FIG. 4A, the thickness of the wrap portion 8 formed by overlapping both end portions 7 of the unvulcanized rubber sheet 6 is set to be twice the thickness of other portions. You. As shown in FIG. 4 (b), the unvulcanized rubber sheet 6 is wound on the mold 5, and the cylindrical shell bag 10 is put on the unvulcanized rubber sheet 6 and heated and pressurized in the vulcanization vessel. A part of the rubber flows into the tooth space 11 of the mold 5, and the unvulcanized rubber of the wrap portion 8 flows in the width direction and the circumferential direction. Displacement and deformation occur. The misalignment of the core wire 3 and the deformation of the core wire remain even after vulcanization molding to make the PLD non-uniform.
[0031]
When the tips of the tapered portions 9a and 9b are not overlapped, as shown in FIG. 5A, the thickness of the wrap portion 8 of the unvulcanized rubber sheet 6 is made equal to the thickness of other portions. As shown in FIG. 5B, the unvulcanized rubber sheet 6 wound around the mold 5 is covered with the shell bag 10 and heated and pressurized in a vulcanizing pot to remove a part of the unvulcanized rubber sheet 6. When the unvulcanized rubber of the wrap portion 8 flows into the tooth groove 11 of the mold 5, it is difficult for the unvulcanized rubber to flow in the width direction and the circumferential direction, and the core wire 3 after vulcanization molding is not easily displaced or deformed.
[0032]
When the tapered portions 9a and 9b overlap, as shown in FIG. 6A, the thickness of the wrap portion 8 of the unvulcanized rubber sheet 6 is made substantially equal to the thickness at other portions. As shown in FIG. 6 (b), the shell bag 10 is put on the unvulcanized rubber sheet 6 wound around the mold 5 and heated and pressed in a vulcanizing pot to remove a part of the unvulcanized rubber sheet 6. When flowing into the tooth groove 10 of the mold 5, the amount of rubber flowing in the width direction and the circumferential direction is small among the unvulcanized rubber of the wrap portion 8, and the core wire 3 after vulcanization is displaced or deformed. Becomes smaller.
[0033]
Next, the result of measuring the PLD of the toothed belt will be described. FIG. 7A shows the PLD at each position in the circumferential direction of the toothed belt, and FIG. 7B shows the PLD near the wrap portion. 7, the horizontal axis represents the belt tooth number. And the vertical axis indicates PLD (unit: mm) at the belt teeth. The PLD in the figure is measured by cutting the toothed belt at a predetermined position in the circumferential direction, and the solid line is the PLD of the toothed belt of the present invention manufactured by forming tapered portions at both ends of the sheet. The dashed line is the PLD of a conventional toothed belt manufactured without forming a tapered portion at the end of the seat.
[0034]
As shown in FIG. 7, in the conventional toothed belt, the measured value of the PLD is disturbed in the vicinity of the wrap portion 8 due to the disorder or deformation of the alignment of the cords 3 due to the flow of the unvulcanized rubber in the wrap portion 8. . On the other hand, in the toothed belt of the present invention, the disturbance of the measured value of the PLD is extremely small, and it can be seen that the disturbance of the alignment of the cords 3 and the deformation do not occur.
[0035]
Next, rotation transmission between the driving pulley and the driven pulley by the toothed belt will be described. FIG. 8A is a diagram showing a method for detecting the relative rotation amount of the driven pulley with respect to the driving pulley. As shown in FIG. 8A, the toothed belt 12 is wound around a driving pulley 14 driven by a motor 13 and a driven pulley 16 connected to a hysteresis brake 15, and the rotation of the driving pulley 14 is driven. Inform the pulley 16.
[0036]
The driving pulley 14 and the driven pulley 16 have the same size, the amount of rotation is detected by the rotary encoders 17 and 18 via the motor 13 and the hysteresis brake 15, and the signal is transmitted to the computer 19. Based on this signal, the computer 19 calculates a relative rotation amount that is a difference between the rotation amount of the driven pulley 16 and the rotation amount of the driving pulley 14.
[0037]
FIG. 8B is a diagram showing the relationship between the driving pulley rotation amount and the relative rotation amount, and shows the relative rotation due to the displacement or deformation of the core wire 3 of the toothed belt 12 wound around the driving pulley 14 and the driven pulley 16. Indicate the difference in quantity. The thick line in the figure is the case where the toothed belt of the present invention is wound and the thin line is the case where the conventional toothed belt is wound and wound.
[0038]
As shown in FIG. 8 (b), when a conventional toothed belt is wound and wound, when the wrap portion is located near the driving pulley 14 or the driven pulley 16, the rotation transmission is disturbed and the relative rotation is generated. The amount is increasing. On the other hand, when the toothed belt of the present invention is wound around, the relative rotation amount is stable at about 0 deg, and it can be seen that the rotation of the driving pulley 14 is smoothly transmitted to the driven pulley 16.
[0039]
As described above, in the conventional toothed belt in which the tapered portion is not formed at the end of the seat, the displacement and deformation of the core wire 3 increase, and the relative rotation amount of the driven pulley 16 with respect to the driving pulley 14 tends to increase. On the other hand, in the toothed belt of the present invention in which the tapered portions are formed at both ends of the seat, since the displacement and deformation of the core wire 3 are small, the disturbance of the rotation transmission between the driving pulley 14 and the driven pulley 16 is suppressed. And the relative rotation amount can be reduced. Thereby, it is possible to prevent vibration in the thickness direction of the toothed belt.
[0040]
It should be noted that the present invention is not limited to the above-described embodiment, and appropriate modifications can be made within the scope of the present invention. For example, instead of continuing the wrap portion 8 of the unvulcanized rubber sheet 6 in a direction orthogonal to the circumferential direction, the wrap portion 8 may be continued in a direction inclined with respect to the circumferential direction as shown in FIG. Further, instead of making the wrap portion 8 continuous in a straight line, as shown in FIG.
[0041]
In addition, the transmission belt of the present invention is not only a toothed belt, but also has a belt body formed by vulcanization molding in an annular shape with both ends of an unvulcanized rubber sheet as an overlapped portion, and a core wire is formed on the belt body. Any material such as a ribbed belt may be used as long as it is buried. FIG. 11 is a perspective view of a main part of the ribbed belt.
[0042]
The ribbed belt has a structure in which an outer peripheral side of a belt main body 20 is covered with a canvas 21, and the belt main body 20 is made of rubber made of, for example, chloroprene rubber. The canvas 21 is, for example, a cloth made of nylon immersed in rubber glue or the like to reinforce the belt body 20.
[0043]
The belt main body 20 is composed of a rib rubber 23 having a plurality of ribs 22 on the inner peripheral side, and an adhesive rubber 24 interposed between the rib rubber 23 and the canvas 21 and bonding them together. The core 25 is buried. The core wire 25 is a polyester cord or the like in which a number of filaments are twisted, and continuously bears in the circumferential direction of the belt body 20 and bears a tensile force acting on the ribbed belt.
[0044]
As a method for manufacturing this ribbed belt, first, the outer peripheral surface of a mold is covered with a canvas jacket formed by annularly sewing a canvas 21 having an adhesive rubber sheet 24 attached to the outer peripheral side, and a core wire 25 is spirally formed on the outside thereof. Wrap around. Next, an unvulcanized rubber sheet is wound around the outside, and both ends are overlapped to form a wrap. In advance, tapered portions are formed at both end portions of the unvulcanized rubber sheet to reduce the thickness of the leading end side, and the thickness of the wrap portion is set to be substantially equal to the thickness at other portions.
[0045]
Here, in the canvas jacket, only the canvas 21 may be circularly sewn, instead of circularly sewing the canvas 21 to which the adhesive rubber sheet 24 is attached. In this case, the mold is covered with a canvas jacket, an adhesive rubber sheet 24 is wound around its outside, and a core wire 25 is wound around its outside. Alternatively, another core rubber sheet may be wound around the outside of the core wire 25, and an unvulcanized rubber sheet may be wound around the outside thereof so that the core wire 25 is embedded in the adhesive rubber 24.
[0046]
The outer shell of the unvulcanized rubber sheet is covered with a cylindrical shell bag and heated and pressurized in a vulcanizing pot to vulcanize and form the unvulcanized rubber sheet to form the belt body 20 in which the core wire 25 is embedded. A rubber body (flat belt) having an inner peripheral surface covered with canvas 21 is formed. After removing the rubber body from the shell bag and the mold and cutting it to a predetermined width, the rib 22 is formed on the rib rubber 23 and turned over, thereby completing the production of the ribbed belt. Other configurations are the same as the method of manufacturing the toothed belt.
[0047]
【The invention's effect】
As is clear from the above description, in the present invention, by forming a tapered portion at both ends of the unvulcanized rubber sheet and vulcanizing and molding into a ring, the thickness of the wrap portion is substantially equal to the thickness at other portions. are doing.
[0048]
Therefore, when the unvulcanized rubber sheet wound around the mold is covered with the shell bag and vulcanized and formed, the unvulcanized rubber in the wrap portion is made difficult to flow in the width direction and the circumferential direction. The displacement and deformation of the cord can be reduced. As a result, disturbance of rotation transmission between the driving pulley and the driven pulley can be suppressed, and the vibration of the transmission belt can be prevented, so that noise during use can be prevented.
[Brief description of the drawings]
FIG. 1 is a perspective view of a main part of a toothed belt (power transmission belt) of the present invention. FIG. 2 (a) shows a state in which an unvulcanized rubber sheet is wound around a mold without overlapping a tapered end. FIG. 3 (a) is an enlarged cross-sectional view of the wrap portion. FIG. 3 (a) is a main portion showing a state where an unvulcanized rubber sheet is wound around a mold with the tip of a tapered portion overlapped. FIG. 4B is a perspective view, FIG. 4B is an enlarged cross-sectional view of the wrap portion. FIG. 4 is a view showing a state before the vulcanization molding, and FIG. FIG. 5 is a diagram showing a state before vulcanization molding, and FIG. 5 (b) is a diagram showing a state after vulcanization molding in a case where the tips of the tapered portions are not overlapped. (A) is a view showing a state before vulcanization molding in which the tip of the tapered portion is overlapped, and (b) is a view showing a state before vulcanization molding. FIG. 7 (a) shows the PLD at each position in the circumferential direction of the toothed belt, and FIG. 7 (b) shows the PLD near the wrap portion of the toothed belt. FIG. 9B is a diagram illustrating a method of detecting a relative rotation amount of the pulley with respect to the driving pulley, and FIG. 9B is a diagram illustrating a relationship between the driving pulley rotation amount and the relative rotation amount. FIG. 10 is a perspective view of a main part showing a state in which a vulcanized rubber sheet is wound around a mold. FIG. 10 is a perspective view of a main part showing a state in which an unvulcanized rubber sheet is wound around a mold with a wrap portion in a finger shape. FIGS. 12A and 12B are views showing a conventional method for manufacturing a toothed belt, in which FIG. 12A is a perspective view showing a state where an unvulcanized rubber sheet is wound around a mold, and FIG. Plan view of wrap after vulcanization molding [Explanation of symbols]
1, 20 Belt body 2 Belt teeth 3, 25 Core wire 4, 21 Canvas 5 Mold 6 Unvulcanized rubber sheet 7 End 8 Wrap 9a, 9b Taper 10 Shell bag 24 Adhesive rubber

Claims (6)

A power transmission belt comprising: a belt main body formed by annularly vulcanizing the both ends of an unvulcanized rubber sheet by overlapping each other; and a core wire continuously embedded in the belt main body in the circumferential direction. A power transmission belt, wherein a tapered portion is formed at an end portion of a rubber sheet so as to reduce a leading end side, and tapered surfaces of tapered portions at both ends of the sheet are overlapped with each other so as to be substantially equal in thickness to other portions. The power transmission belt according to claim 1, wherein the taper portion has an inclination angle of 15 ° to 70 ° with respect to a circumferential direction of the tapered surface. The power transmission belt according to claim 1, wherein a tip end of the tapered portion overlaps a center of the other tapered portion in a circumferential direction. The power transmission belt according to claim 3, wherein the length of the overlap in the circumferential direction is 10 mm or less. An annular canvas jacket is put on the outer peripheral surface of the mold in which the tooth grooves corresponding to the belt teeth are formed, a core wire is wound around the outside, and then an unvulcanized rubber sheet is wound around the outside. Both ends of the vulcanized rubber sheet are overlapped, and further, a cylindrical shell bag is put on the outside of the vulcanized rubber sheet and heated and pressurized in a vulcanizing pot, so that a part of the unvulcanized rubber sheet is used as a tooth of the mold. The method of vulcanizing the unvulcanized rubber sheet while flowing into the groove, and manufacturing a toothed belt in which the belt teeth of the belt body in which the cords are embedded is covered with canvas, A method of manufacturing a toothed belt, comprising: forming a tapered portion in advance at both ends of a sheet so as to reduce the thickness of the leading end side; An annular canvas is placed on the outer peripheral surface of the mold, an adhesive rubber sheet is arranged on the outer peripheral side, a core wire is wound around the outer side, and then an unvulcanized rubber sheet is wound around the outer side, and the unvulcanized rubber sheet is wound. The unvulcanized rubber sheet is vulcanized and molded by placing both ends of the rubber sheet on top of each other, covering the outside with a cylindrical shell bag, and applying heat and pressure in a vulcanization oven, thereby embedding the core wire. A rubber body is formed by covering the inner peripheral surface of the belt body with canvas, the rubber body is removed from the shell bag and the mold, and a rib is formed on the outer peripheral surface of the belt body by polishing or the like. In the method of manufacturing a ribbed belt by turning over the rubber body, the unvulcanized rubber sheet is formed in advance with a tapered portion having a thinner tip end at both ends thereof, and the tapered surfaces of the tapered portions at both ends of the sheet are overlapped. Vulcanization Method of manufacturing a ribbed belt which is characterized in that shape.

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