JP2000334856A - Manufacture of transmission belt and transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission belt formed of a rubber composition composed mainly of a less sticky rubber, and a method for manufacturing the transmission belt. SOLUTION: Materials are set in a cylindrical mold through a sequence of steps such as a canvas setting step to set a barrel-shaped canvas treated to be adhesive with a mucilage in place over a cylindrical mold, a reinforcing cord setting step to wind the reinforcing cord spirally over the barrel-shaped canvas and a cylindrical rubber setting step to cover the reinforcing cord with a cylindrical rubber consisting of an unvulcanized rubber composition from right above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a power transmission belt and a power transmission belt.

[0002]

2. Description of the Related Art Chloroprene rubber (hereinafter referred to as "CR") is most commonly used as a rubber material for a power transmission belt. However, since CR contains chlorine atoms in the molecule, the power transmission belt fulfills its function, and there is a problem that harmful chlorine compounds are generated when the CR is finally disposed or incinerated. By the way, ethylene-propylene-diene terpolymer rubber (hereinafter referred to as "EPDM")
Has elements that can improve cold resistance and heat resistance more than CR,
Further, since the molecular skeleton is composed of carbon and hydrogen, it has characteristics such as not containing a chlorine atom in the molecule like CR, and being cheaper than CR. Then, in recent years, the rubber material for the power transmission belt is shifting from CR to EPDM.

[0003]

SUMMARY OF THE INVENTION However, EPD
Since the kneaded rubber of M has lower adhesiveness than the kneaded rubber of CR, employing the same method of manufacturing a power transmission belt as in the related art causes many problems in belt forming processing. For example, taking the manufacturing process of a V-ribbed belt as an example, there are the following problems.

[0004] First, as shown in FIG. 13, a bias cut is applied to canvas a which has been glued with rubber glue, and then, as shown in FIG. A lap joint can be formed using the adhesiveness of rubber in a canvas bonded with glue, but such a lap joint cannot be formed in a canvas bonded with EPDM rubber glue because EPDM has low adhesiveness. Similarly, in a case where a canvas a bonded with rubber glue is wound around a cylindrical mold b and the cylindrical mold b is covered with the canvas a (see FIG. 15 (a)), the canvas glued with the rubber glue of CR is cylindrical. Although it can be wound around a mold and wrap jointed, such a wrapping and wrap joint cannot be made with canvas glued with EPDM rubber glue.

Further, as shown in FIG. 16, a first adhesive rubber sheet d formed into a sheet by a calender roll c is wound up while sandwiching a cloth (ply cloth) so as to prevent the sheets from sticking to each other. Then, the first adhesive rubber sheet d
Is wound from above the canvas a set in the cylindrical mold b (see FIG. 15A), the first adhesive rubber sheet of CR can be wound around the cylindrical mold and wrap jointed, but the EPDM of CRDM can be used. Since the first adhesive rubber sheet has low adhesiveness, such winding and lap joint cannot be performed.

Further, when the reinforcing cord e is spirally wound from above the first adhesive rubber sheet d (see FIG. 15B), the position of the reinforcing cord is determined by the adhesiveness of the rubber in the first adhesive rubber sheet of CR. Although the holding is performed, since the first adhesive rubber sheet of EPDM has low tackiness, the position of the reinforcing cord may be shifted.

When the second adhesive rubber sheet f is wound on the wound reinforcing cord e, the second adhesive rubber sheet of CR can be wound around a cylindrical mold and lap jointed. (1) Since the adhesive rubber sheet has low tackiness, such winding and lap joint cannot be performed.

[0008] Finally, when the short-fiber-containing rubber sheet g mixed with short fibers is wound around the adhesive rubber sheet several times (see FIG. 15 (c)), the short-fiber-containing rubber sheet of CR has a rubber adhesive property. The rubber sheet can be wound, but such a rubber sheet containing short fibers of EPDM cannot be wound because of low adhesiveness.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a power transmission belt formed of a rubber composition having poor adhesion and a power transmission belt. .

[0010]

In order to achieve the above object, the present invention provides a method for manufacturing a power transmission belt by covering a cylindrical mold with a cylindrical canvas bonded by a rubber glue, and forming a reinforcing cord on the cylindrical mold. The method includes a step of spirally winding and a step of coating a cylindrical rubber made of an unvulcanized rubber composition thereon.

Specifically, the invention according to claim 1 is a method for manufacturing a power transmission belt, comprising: a canvas setting step of covering a cylindrical mold bonded with rubber glue on a cylindrical mold; A reinforcing cord setting step of spirally winding a reinforcing cord from above a mold, and a cylindrical rubber setting step of covering a cylindrical rubber formed of an unvulcanized rubber composition on a cylindrical mold set with the reinforcing cord. A method for manufacturing a power transmission belt, comprising:

According to a second aspect of the present invention, in the method for manufacturing a power transmission belt according to the first aspect, the rubber glue used for bonding the tubular canvas is made of EPDM or ethylene-propylene rubber (hereinafter, “EPR”). ) Is formed as a main rubber, and the cylindrical rubber is made of EPDM or EPR.
A method for manufacturing a power transmission belt, comprising: a rubber composition mainly composed of a rubber.

According to the above-described manufacturing method, since the canvas is formed in a cylindrical shape, it is not necessary to lap the canvas on a cylindrical mold. Therefore, even a canvas that has been subjected to an adhesive treatment with rubber adhesive such as EPDM or EPR having low tackiness can be set on a cylindrical mold.

Since the cylindrical rubber formed of the unvulcanized rubber composition is placed on the cylindrical mold around which the reinforcing cord is wound, there is no need to wind the rubber sheet. Therefore, even an unvulcanized rubber composition such as EPDM or EPR having low adhesiveness can be set on a cylindrical mold.

Further, since the operation of wrapping the wrap joint of the canvas and the rubber sheet on the cylindrical mold is not required as described above, the efficiency of the process of setting the material to the cylindrical mold is improved.

According to a third aspect of the present invention, in the method for manufacturing a power transmission belt according to the first or second aspect, the entire outer surface of the tubular canvas is formed of an unvulcanized rubber composition and reinforced. A first adhesive rubber layer for holding the cord at a predetermined distance from the canvas is provided, and the entire inner surface of the cylindrical rubber is made of the same rubber composition as the first adhesive rubber layer and is provided with the first adhesive rubber layer. A second adhesive rubber layer for sandwiching a reinforcing cord between the rubber members, and a cylindrical rubber in which short fibers whose fiber axes are oriented in the axial direction are dispersed. is there.

According to a fourth aspect of the present invention, in the method for manufacturing a power transmission belt according to the third aspect, the rubber paste used for bonding the tubular canvas is made of EPDM or EPR as a main rubber, The rubber-like rubber is formed of a rubber composition containing EPDM or EPR as a main rubber.
The method of manufacturing a power transmission belt, wherein the adhesive rubber and the second adhesive rubber are formed of a rubber composition containing EPDM or EPR as a main rubber.

According to the above manufacturing method, since the first adhesive rubber layer formed of the unvulcanized rubber composition is provided on the entire surface of the tubular canvas, the first adhesive rubber sheet is provided on the cylindrical mold. No need to wrap around and wrap joints. Therefore, even the first adhesive rubber such as EPDM or EPR having low adhesiveness can be set on the cylindrical mold in a form in which the first adhesive rubber layer is provided on the outer surface of the canvas in advance.

Since the second adhesive rubber layer having the same rubber composition as the first adhesive rubber layer is provided on the entire inner surface of the cylindrical rubber, the second adhesive rubber sheet is wound around the cylindrical mold and wrapped. There is no need to make joints. Therefore,
Even a second adhesive rubber such as EPDM or EPR having low adhesiveness can be set on a cylindrical mold by providing a second adhesive rubber layer on the inner surface of the cylindrical rubber.

Further, as described above, the operations of winding the adhesive rubber sheet on the cylindrical mold and lap joint are not required, and the efficiency of the process of setting the material on the cylindrical mold is improved.

Since the reinforcing cord is held at a predetermined distance from the canvas by the first adhesive rubber layer, the reinforcing cord of the transmission belt can be embedded at a predetermined position. Further, the reinforcing cord is sandwiched between rubbers having the same composition, that is, the first adhesive rubber layer and the second adhesive rubber layer, and is vulcanized and integrated, so that the reinforcing cord is firmly adhered to the rubber and embedded.

Also, since short fibers whose fiber axes are oriented in the cylindrical axis direction are dispersed in the cylindrical rubber, the short fibers are oriented in the belt width direction in the transmission belt body manufactured by this method. Thus, the elastic modulus of the rubber in the belt width direction increases.

According to a fifth aspect of the present invention, in the method of the second or fourth aspect, the surface of the first adhesive rubber layer is provided with a surface oxidation preventing means before the reinforcing cord setting step. A method for manufacturing a power transmission belt, characterized in that:

According to the above manufacturing method, the oxidation of the surface of the first adhesive rubber layer provided on the outer surface of the canvas is suppressed, so that the adhesiveness of the surface of the first adhesive rubber layer can be maintained. Therefore, even with the first adhesive rubber layer such as EPDM or EPR having low adhesiveness, it is possible to maintain a certain degree of adhesiveness by taking such means for preventing surface oxidation, and a reinforcing cord is wound thereon. In this case, the position of the reinforcing cord is fixed.

Here, the surface oxidation preventing means is not particularly limited, but the surface on the adhesive rubber side of the canvas to which the adhesive rubber sheet has been attached is covered with a sheet of polyethylene or the like, or before the reinforcing cord is wound. Means include wiping the surface of the first adhesive rubber layer with a solvent.

According to a sixth aspect of the present invention, in the method of the fifth aspect, the surface oxidation preventing means covers the exposed surface of the first adhesive rubber layer with a polyethylene sheet. And a method of manufacturing a power transmission belt.

According to the above manufacturing method, the presence of the polyethylene sheet cuts off the contact between the surface of the first adhesive rubber layer and the air, so that the function of the invention described in claim 5 can be performed specifically. Further, since the surface of the first adhesive rubber layer is kept smooth by the polyethylene sheet, the contact area with the reinforcing cord wound thereon can be widened, and the reinforcing cord is strongly supported on the first adhesive rubber layer. Will be done.

According to a seventh aspect of the present invention, there is provided a power transmission belt provided with a canvas bonded to the surface of the belt with a rubber paste.
The rubber glue used for the bonding process of the canvas is formed of EPDM or EPR as a main rubber, and the belt body is formed of a rubber composition of EPDM or EPR as a main rubber, and is exposed on the surface of the canvas. The connecting portion between the canvases is a power transmission belt characterized in that the ends of the canvases are joined by abutting each other.

According to the above configuration, the joining portions of the canvas appearing on the belt surface are joined to each other, so that the joining portion does not appear as a step on the belt surface as in the case of a lap joint. Therefore, the step generated at the joint of the canvas does not come into contact with the pulley and generate abnormal noise, and the belt is not smoothly wound around the pulley due to the presence of the step, so that smooth power transmission is not hindered. .

Further, the rubber composition forming the belt body fills in the recess formed in the joint part of the canvas by flowing into the joint part of the canvas at the time of vulcanization molding, and the rubber composition forming the belt body is EPDM or Since EPR is the main rubber, the surface of the canvas of the belt is extremely smooth. Therefore, also from this point, the prevention of abnormal noise generated when the transmission belt runs and the smooth transmission of power are achieved.

[0031]

As described above, according to the first or second aspect of the present invention, since the canvas is formed in a tubular shape, it is not necessary to perform a lap joint of the canvas on a cylindrical mold. Therefore, even a canvas that has been subjected to an adhesive treatment with rubber adhesive such as EPDM or EPR having low tackiness can be set on a cylindrical mold. Further, since the cylindrical rubber formed of the unvulcanized rubber composition is placed on the cylindrical mold around which the reinforcing cord is wound, there is no need to wind the rubber sheet.
Therefore, even an unvulcanized rubber composition such as EPDM or EPR having low adhesiveness can be set on a cylindrical mold. Furthermore, since the work of wrapping the wrap joint of the canvas and the rubber sheet on the cylindrical mold is not required as described above, the efficiency of the process of setting the material to the cylindrical mold is improved. In this way, it becomes possible to manufacture a power transmission belt formed of a rubber composition having poor tackiness.

According to the third or fourth aspect of the present invention, since the first adhesive rubber layer formed of the unvulcanized rubber composition is provided on the entire surface of the tubular canvas, the first adhesive rubber sheet has a cylindrical shape. There is no need to wrap around the mold and wrap joints. Therefore, low adhesive EPDM or EPR
Even with the first adhesive rubber, it is possible to set the first adhesive rubber layer on the outer surface of the canvas in advance on the cylindrical mold. Also, since the second adhesive rubber layer having the same rubber composition as the first adhesive rubber layer is provided on the entire inner surface of the cylindrical rubber, the second adhesive rubber sheet is wound around the cylindrical mold and lap jointed. No need. Therefore,
Even a second adhesive rubber such as EPDM or EPR having low adhesiveness can be set on a cylindrical mold by providing a second adhesive rubber layer on the inner surface of the cylindrical rubber. Further, as described above, the operations of winding the adhesive rubber sheet on the cylindrical mold and lap joint are not required, and the efficiency of the process of setting the material in the cylindrical mold is improved. Since the reinforcing cord is held at a position spaced apart from the canvas by the first adhesive rubber layer, the reinforcing cord of the transmission belt can be embedded at a predetermined position. Further, the reinforcing cord is sandwiched between rubbers having the same composition, that is, the first adhesive rubber layer and the second adhesive rubber layer, and is vulcanized and integrated, so that the reinforcing cord is firmly adhered to the rubber and embedded. In addition, cylindrical rubber has
Since the short fibers whose fiber axes are oriented in the cylindrical axis direction are dispersed, the short fibers are oriented in the belt width direction in the power transmission belt body manufactured by this method, whereby the elasticity of the rubber in the belt width direction is increased. Rate is higher.

According to the fifth aspect of the invention, in addition to the effect of the second or fourth aspect, the oxidation of the surface of the first adhesive rubber layer provided on the outer surface of the canvas is suppressed, so that the first adhesive rubber is provided. The tackiness of the layer surface can be maintained. Therefore,
Even with the first adhesive rubber layer such as EPDM or EPR having low adhesiveness, it is possible to maintain a certain degree of adhesiveness by taking such means for preventing surface oxidation, and when a reinforcing cord is wound thereon, The position of the reinforcing cord is fixed.

According to the sixth aspect of the present invention, the presence of the polyethylene sheet interrupts the contact between the surface of the first adhesive rubber layer and the air, so that the function of the fifth aspect of the present invention can be achieved. Further, since the surface of the first adhesive rubber layer is kept smooth by the polyethylene sheet, the contact area with the reinforcing cord wound thereon can be widened, and the reinforcing cord is strongly supported on the first adhesive rubber layer. Will be done.

According to the seventh aspect of the present invention, since the joining portions of the canvas appearing on the belt surface are joined to each other,
The joint does not appear as a step on the belt surface as in the case of a lap joint. Therefore, the step generated at the joint of the canvas comes into contact with the pulley and generates abnormal noise,
Since the belt is not smoothly wound around the pulley due to the presence of the step, smooth power transmission is not hindered. In addition, the rubber composition forming the belt body is filled with the concave portion formed in the joint portion of the canvas by flowing into the joint portion of the canvas during vulcanization molding, and the rubber composition forming the belt body mainly includes EPDM or EPR. Therefore, the canvas surface of the belt becomes extremely smooth. Therefore, also from this point, the prevention of abnormal noise generated when the transmission belt runs and the smooth transmission of power are achieved.

[0036]

(Embodiment 1) Hereinafter, a method for manufacturing a V-ribbed belt according to Embodiment 3 of the present invention will be described in detail with reference to the drawings.

<Process for preparing canvas> As shown in FIG.
The canvas 1 in which the rubber composition containing M is immersed in a rubber paste obtained by dissolving the rubber composition in a solvent and dried by heating is heated by the first roll 2a and the second roll 2b of the first calender roll 2 and is mainly made of EPDM. A rubber laminated canvas in which the first adhesive rubber layer 3 is integrally formed on the surface of the canvas 1 by passing the sheet between the second roll 2b and the third roll 2c together with the sheet-like first adhesive rubber made of the vulcanized rubber composition. Get 4. Then, the surface of the first adhesive rubber layer 3 of the rubber laminated canvas 4 is covered with a polyethylene sheet 5 and wound up.

Next, as shown in FIG. 2, the rubber laminated canvas 4 wound together with the polyethylene sheet 5 is subjected to bias cutting at a predetermined angle, and a number of parallelogram pieces 4a, 4a,.
And Then, as shown in FIG. 3, a large number of parallelogram pieces 4a, 4a,... Are joined so that the cut ends of the parallelogram pieces 4a are on both sides, and the rubber laminated canvas 4 is formed again. As a result, the warp and the weft of the canvas 1 make a predetermined angle with the length direction of the rubber laminated canvas 4, that is, the belt length direction, and stable running of the transmission belt is realized. When joining the parallelogram pieces 4a, the joining ends are abutted with each other and sewn with a sewing machine so that a step due to overlapping does not occur.

Subsequently, a required amount of rubber laminated canvas 4 pieces are cut out from the sewn rubber laminated canvas 4 in accordance with the circumference of a cylindrical mold used for molding. At this time, the rubber laminated canvas 4 is cut in parallel with the sewn canvas joint 6. Then, the cut ends of the four pieces of rubber laminated canvas with the first adhesive rubber layer 3 side facing outside are butted together and sewn with a sewing machine. As shown in FIG. The canvas 7 is created.

When suturing with a bias cut and a sewing machine, the polyethylene sheet 5 stuck on the surface of the first adhesive rubber layer 3 is not peeled except for the portion to be sewn.

<Cylindrical Rubber Preparation Step> As shown in FIG. 5, an unvulcanized rubber composition 8 mainly composed of EPDM mixed with short fibers is formed into a pellet and put into an extruder 9 to expand the cylinder. Rubber-like cylindrical body 1 of required thickness from die 10
1 is extruded, and this rubber-like cylindrical body 11 is cut open by a cutter 12 in the extrusion direction to form a rubber-like flat plate 13. At this time, the short fibers contained in the unvulcanized rubber composition 8 are oriented in the circumferential direction of the extruded rubber-like cylinder 11, that is, in the width direction of the rubber-like flat plate 13.

Next, the extruded rubber-like flat plate 13 is
As shown in FIG. 6, the second calender roll 14 is passed between the second roll 14b and the third roll 14c together with the second adhesive rubber heated by the first roll 14a and the second roll 14b. A rubber-like laminated flat plate 16 having the second adhesive rubber layer 15 integrally formed on the surface is obtained. The second adhesive rubber is made of an unvulcanized rubber composition having the same composition as the first adhesive rubber.

Then, as shown in FIG. 7A, a length necessary for molding is cut out from the rubber-like laminated flat plate 16. At this time, as shown in FIG. 7B, the cut is made so that both cut surfaces are parallel and make a predetermined angle with respect to the thickness direction of the rubber-like laminated flat plate 16.

Finally, the cut surfaces of the cut rubber-like laminated flat plate 16 are abutted so that the side of the second adhesive rubber layer 15 is on the inner side, and the abutted portion is further heated as shown in FIG. 17 and heated and pressed to form a cylindrical rubber 1 having a second adhesive rubber layer 15 provided inside.
Create 8.

<Canvas Setting Step> As shown in FIG. 9, the tubular canvas 7 is put on a cylindrical mold 19.

<Reinforcing cord setting step> The polyethylene sheet 5 on the surface of the first adhesive rubber layer 3 provided on the tubular canvas 7 is peeled off, so that the first adhesive rubber layer 3 is exposed.
Then, as shown in FIG. 10, the reinforcing cord 20 is spirally wound around the cylindrical mold 19 in the circumferential direction.

<Cylindrical Rubber Setting Step> As shown in FIG. 11, the cylindrical rubber 18 is put on a cylindrical mold 19 around which a reinforcing cord 20 is wound.

<Vulcanization Step> A cylindrical mold 19 in which a cylindrical rubber 18 is set is put in a vulcanization can, and EPDM is vulcanized at a predetermined temperature and pressure for a predetermined time.

<Grinding Step> The cylindrical mold 19 is taken out of the vulcanizing can, and the cylindrical vulcanized molded body formed on the peripheral surface of the cylindrical mold 19 is released. Then, the outer peripheral surface of the removed vulcanized molded body is ground with a grindstone to form a large number of ribs extending in the circumferential direction of the cylindrical body and extending over the entire circumference.

<Width cutting step> The ground cylinder is cut into a required width in a direction perpendicular to the axis, and the V-ribbed belt A
Is manufactured.

Next, the operation and effect will be described.

According to the method of manufacturing the V-ribbed belt described above, since the tubular canvas 7 is used, it is not necessary to lap the canvas on the cylindrical mold 19. Therefore, even a canvas that has been subjected to an adhesive treatment with low adhesive EPDM rubber glue can be set on the cylindrical mold 19.

Further, since the first adhesive rubber layer 3 made of an unvulcanized rubber composition mainly composed of EPDM is provided on the entire surface of the tubular canvas 7, the cylindrical mold of the first adhesive rubber sheet is provided. There is no need to wrap over 19 and wrap joints. Therefore, even the first adhesive rubber of EPDM having low adhesiveness can be set on the cylindrical mold 19 in such a manner that the first adhesive rubber layer 3 is provided on the outer surface of the canvas in advance.

The two cut surfaces of the rubber laminated plate 16 cut out from the rubber laminated plate 16 are parallel and form a predetermined angle with respect to the thickness direction of the rubber laminated plate 16. Therefore, the cylindrical rubber 1 is heated by the heating press 17.
Since the contact area of the cut surfaces to be abutted with each other is larger than that in the case where the rubber-like laminated flat plate 16 is cut in the thickness direction, the cylindrical rubber 18 to be formed is formed.
Are tightly adhered to each other.

Further, since the cylindrical rubber 18 made of a rubber composition mainly composed of EPDM is put on the cylindrical mold 19 around which the reinforcing cord 20 is wound, it is not necessary to wind the rubber sheet. Therefore, EPDM with low tackiness
The unvulcanized rubber composition can be set on the cylindrical mold 19.

The second adhesive rubber layer 15 having the same rubber composition as the first adhesive rubber layer 3 is formed on the entire inner surface of the cylindrical rubber 18.
Is provided, there is no need to wind the second adhesive rubber sheet onto the cylindrical mold 19 and perform lap joint. Therefore, even the second adhesive rubber of EPDM having low adhesiveness can be set on the cylindrical mold 19 in such a manner that the second adhesive rubber layer 19 is provided on the inner surface of the cylindrical rubber 18.

Since the work of wrapping the wrap joint of the canvas and the adhesive rubber sheet on the cylindrical mold 19 is not required, the efficiency of the process of setting the material in the cylindrical mold can be improved.

Since the reinforcing cord 20 is held at a predetermined distance from the canvas by the first adhesive rubber layer 3, the reinforcing cord 20 can be embedded at a predetermined position of the belt. Further, the reinforcing cord 20 is provided with the first adhesive rubber layer 3.
The second adhesive rubber layer 15 is sandwiched between rubbers of the same composition and vulcanized and integrated, so that it is firmly adhered to the rubber and embedded.

Since short fibers whose fiber axes are oriented in the cylindrical axis direction are dispersed in the cylindrical rubber 18, the short fibers are oriented in the belt width direction at each rib portion of the manufactured V-ribbed belt A. As a result, the elastic modulus of the rib portion in the belt width direction increases.

Also, the presence of the polyethylene sheet 5 covering the surface of the first adhesive rubber layer 3 blocks the contact of the surface of the first adhesive rubber layer 3 with air, thereby suppressing the oxidation of the surface of the first adhesive rubber layer 3. . As a result, even the first adhesive rubber layer 3 of EPDM having low adhesiveness can maintain a certain degree of adhesiveness, and when the reinforcing cord 20 is wound thereon, the position of the reinforcing cord 20 is fixed.

(Embodiment 2) FIG. 12 shows a V-ribbed belt A according to Embodiment 2 of the present invention. V-ribbed belt A
Has a back canvas 21 attached to the back of the belt integrally with the belt, and a plurality of reinforcing cords 22 embedded in the lower portion of the back canvas 21 in the longitudinal direction of the belt.
3, and three rib rubber layers 24, 24, 24 extending in the belt length direction are provided below the adhesive rubber layer 23. The back canvas 21 has been subjected to an adhesive treatment with a rubber paste containing EPDM, and the adhesive rubber layer 23 and the rib rubber layer 24 are formed of a rubber composition mainly composed of EPDM. Furthermore, a rib rubber layer 24
Has short fibers oriented in the belt width direction. The connecting portions of the canvas exposed on the surface of the rear canvas 21 are connected by abutting the ends of the rear canvas 21.

Next, the operation and effect will be described.

In the above-described V-ribbed belt A, since the joining portions of the back canvas 21 on the back surface of the belt are joined to each other, they do not appear as steps on the belt surface as in the case of lap joint. . Therefore, the step generated at the joint portion of the rear canvas 21 comes into contact with the pulley and generates an abnormal noise, and the belt is not smoothly wound around the pulley due to the presence of the step, so that smooth power transmission is hindered. There is no.

The rubber composition forming the belt body fills in the recess formed in the joint portion of the canvas by flowing into the joint portion of the back canvas 21 during vulcanization molding, and the rubber composition forming the belt body is EPDM. , The surface of the canvas of the belt is extremely smooth. Therefore, also from this point, the prevention of abnormal noise and the smooth transmission of power generated when the power transmission belt runs can be achieved.

(Embodiment 3) Hereinafter, Embodiment 3 of the present invention will be described.
The method for manufacturing the toothed belt according to the above is described.

<Canvas Preparing Step> A nylon canvas using a wooly-processed nylon yarn as a weft is immersed in a rubber paste obtained by dissolving a rubber composition containing EPDM in a solvent, and dried by heating. The required amount of this bonded canvas is cut out according to the circumference of the cylindrical mold. Then, the ends are butted and sewn with a sewing machine to form a tubular canvas. At this time, the wooly-processed nylon thread extends in the circumferential direction of the tubular canvas.

<Cylindrical Rubber Preparation Step> The unvulcanized rubber composition mainly composed of EPDM is made into a pellet and is put into an extruder, and a rubbery cylinder having a required thickness is extruded from a cylindrical expansion die. Then, the rubber-like cylindrical body is cut open by a cutter in the extrusion direction to form a rubber-like flat plate.

Next, a flat plate having a length required for molding is cut out from the rubber-like flat plate. At this time, the cut piece is cut so that both cut surfaces of the cut out flat plate piece become parallel and make a predetermined angle with respect to the thickness direction of the rubber-like flat plate.

Lastly, the cut surfaces of the cut rubber-like flat plate were abutted, and the portion was sandwiched by a heating press.
Heat and pressurize to make cylindrical rubber.

<Canvas setting step> The tubular canvas is covered on a cylindrical mold.

<Reinforcing Cord Setting Step> A reinforcing cord is spirally wound around the cylindrical mold covered with the tubular canvas in the circumferential direction of the mold.

<Cylindrical Rubber Setting Step> The cylindrical rubber is put on a cylindrical mold around which a reinforcing cord is wound.

<Vulcanization Step> A cylindrical mold in which a cylindrical rubber is set is placed in a vulcanization can, and EPDM is vulcanized at a predetermined temperature and pressure for a predetermined time.

<Width cutting step> The cylindrical mold is taken out of the vulcanizing can, and the cylindrical vulcanized molded body formed on the periphery of the cylindrical mold is released. Then, the cylindrical vulcanized molded body is cut into a desired width in a direction perpendicular to the axis, and the toothed belt B is manufactured.

Next, the operation and effect will be described.

According to the above-described method of manufacturing the toothed belt, since the canvas is formed in a cylindrical shape, there is no need to perform a lap joint of the canvas on a cylindrical mold. Therefore, EPD with low tackiness
Even if the canvas is glued with M rubber glue, it can be set on a cylindrical mold.

The two cut surfaces of the rubber plate cut out from the rubber plate are parallel and at a predetermined angle to the thickness direction of the rubber plate. Therefore, when the cylindrical rubber is formed by the heating press, the contact area of the cut surfaces to be abutted becomes wider than when the rubber-shaped laminated flat plate is cut in the thickness direction, and the joint portion of the formed cylindrical rubber is formed. It becomes tightly adhered.

Since the cylindrical rubber formed of the unvulcanized rubber composition mainly composed of EPDM is put on the cylindrical mold around which the reinforcing cord is wound, it is not necessary to wind the rubber sheet. Therefore, even an unvulcanized rubber composition of EPDM having low adhesiveness can be set on a cylindrical mold.

Further, since the work of wrapping the wrap joint of the canvas and the rubber sheet on the cylindrical mold as described above becomes unnecessary, the efficiency of the process of setting the material in the cylindrical mold is improved. .

(Other Embodiments) In the first embodiment, the bias-cut canvas is joined by joining the joining ends. However, the present invention is not limited to this, and a part of the ends is overlapped. May be joined together. The bias cut canvas was joined by sewing with a sewing machine.However, the present invention is not limited to this, and includes a case where the joining ends are butt or overlapped with each other and rubber glue is applied to the joining portions and joined. .

In the first and third embodiments, the canvas is formed by butt-joining the ends, but is not limited to the butt-joining as described above. Further, the joining means is not limited to the sewing by the sewing machine, similarly to the above.

In the first embodiment, the canvas and the adhesive rubber are integrated by using a calendar roll. However, the present invention is not limited to this. A solvent is applied to either the canvas or the first adhesive rubber sheet. And the case where both are bonded together to be integrated. Also, the means for integrating the rubber-like flat plate and the second adhesive rubber is not limited to the one using the calender roll, as in the above.

In Embodiments 1 and 3, the cut ends of the rubber-like flat plate pieces are butted and joined by a hot press to form a cylindrical rubber. However, the present invention is not particularly limited to this method. The case where rubber glue is applied and joined is also included.

In the first and third embodiments, the rubber material such as rubber glue used for the bonding process of the canvas is made of EP.
Although DM was used, it is not particularly limited to this,
EPR having poor adhesion may be used. Also, CR,
The present invention can also be applied to hydrogenated nitrile rubber (H-NBR) and the like, and in this case, the effect of increasing the efficiency of the process of setting the material in the cylindrical mold is obtained.
Further, the main rubber constituting each member such as the rubber paste used for the bonding process of the canvas and the rubber composition forming the belt body is not limited to the same rubber type, and different types of rubber are used as the main rubber. It may be something.

[Brief description of the drawings]

FIG. 1 is a side view of a first calender roll.

FIG. 2 is a front view of the canvas before a bias cut is performed.

FIG. 3 is a front view of the canvas in which the joint ends of the bias-cut canvas are joined together by butt-stitching and joining with a sewing machine.

FIG. 4 is a perspective view of a cylindrical canvas.

FIG. 5 is a side sectional view of the extrusion molding machine.

FIG. 6 is a side view of a second calender roll.

FIG. 7 (a) is a top view of a rubber-like laminated flat plate,
FIG. 7B is a side view.

FIG. 8 is a perspective view showing a state in which a rubber-like laminated flat plate whose cut ends are butted is set in a heating joint press.

FIG. 9 is a perspective view of a cylindrical mold covered with a tubular canvas provided with a first adhesive rubber layer on the outside.

FIG. 10 is a perspective view showing a reinforcing cord setting step.

FIG. 11 is a perspective view showing a step of setting a cylindrical rubber in a cylindrical mold.

FIG. 12 is a perspective view of a V-ribbed belt A.

FIG. 13 is a front view of the canvas before the bias cut is performed.

FIG. 14 is a front view of the canvas in which the joining ends of the bias-cut canvas are overlapped and joined by rubber adhesiveness.

FIG. 15A is a perspective view showing a step of winding a canvas and a first adhesive rubber around a cylindrical mold, and FIG.
FIG. 15B is a perspective view showing a step of winding a reinforcing cord around a cylindrical mold, and FIG. 15C is a perspective view showing a step of winding a fiber-containing rubber sheet around the cylindrical mold.

FIG. 16 is a perspective view of a calender roll for processing adhesive rubber into a sheet shape.

[Explanation of symbols]

 Reference Signs List 1 canvas 2 first calendar 2a first roll 2b second roll 2c third roll 3 first adhesive rubber layer 4 rubber laminated canvas 4a parallelogram piece 5 polyethylene rubber sheet 6 canvas joint 7 tubular canvas 8 rubber with short fibers Composition 9 Extruder 10 Cylinder expansion die 11 Rubber cylinder 12 Cutter 13 Rubber plate 14 Second calender 14a First roll 14b Second roll 14c Third roll 15 Second adhesive rubber layer 16 Rubber laminate plate 17 Heating Press machine 18 Cylindrical rubber 19 Cylindrical mold 20 Reinforcement cord 21 Back canvas 22 Reinforcement cord 23 Adhesive rubber layer 24 Rib rubber layer a Canvas b Cylindrical mold c Calendar roll d First adhesive rubber sheet e Reinforcement cord f Second adhesive rubber sheet g Rubber sheet with short fibers

Claims (7)

[Claims] 1. A method for manufacturing a power transmission belt, comprising: a canvas setting step of covering a cylindrical mold covered with a rubber paste with a cylindrical canvas, and spirally reinforcing a reinforcing cord from above the cylindrical mold covered with the tubular canvas. A reinforcing cord setting step of winding the reinforcing cord, and a cylindrical rubber setting step of covering a cylindrical rubber formed of an unvulcanized rubber composition on a cylindrical mold on which the reinforcing cord is set. Belt manufacturing method. 2. The method for manufacturing a power transmission belt according to claim 1, wherein the rubber glue used for the bonding treatment of the tubular canvas is ethylene-based.
Propylene-diene terpolymer rubber or ethylene-
A method for producing a power transmission belt, comprising: forming a propylene rubber as a main rubber; and forming the cylindrical rubber from a rubber composition containing an ethylene-propylene-diene terpolymer rubber or an ethylene-propylene rubber as a main rubber. . 3. The method for manufacturing a power transmission belt according to claim 1, wherein the entire outer surface of the tubular canvas is formed of an unvulcanized rubber composition and a reinforcing cord is provided at a predetermined distance from the canvas. A first adhesive rubber layer is provided for holding at an open position, and the entire inner surface of the cylindrical rubber is formed of the same rubber composition as the first adhesive rubber layer, and a reinforcing cord is provided between the first adhesive rubber layer and the first adhesive rubber layer. A method for manufacturing a power transmission belt, comprising: a second adhesive rubber layer for sandwiching; and short fibers having fiber axes oriented in an axial direction are dispersed in a cylindrical rubber. 4. The method of manufacturing a power transmission belt according to claim 3, wherein the rubber glue used for the bonding treatment of the tubular canvas is ethylene-based.
Propylene-diene terpolymer rubber or ethylene-
The propylene rubber is formed as a main rubber, the cylindrical rubber is formed of a rubber composition having ethylene-propylene-diene terpolymer rubber or ethylene-propylene rubber as a main rubber, and the first adhesive rubber and the second adhesive rubber are: A method for producing a power transmission belt, comprising a rubber composition containing ethylene-propylene-diene terpolymer rubber or ethylene-propylene rubber as a main rubber. 5. The transmission belt manufacturing method according to claim 2, wherein a surface oxidation preventing means is provided on a surface of the first adhesive rubber layer before the reinforcing cord setting step. Belt manufacturing method. 6. The method of manufacturing a power transmission belt according to claim 5, wherein the surface oxidation preventing means covers the exposed surface of the first adhesive rubber layer with a polyethylene sheet. Method. 7. A power transmission belt provided with a canvas bonded to a surface of the belt with rubber glue, wherein the rubber glue used for the bonding process of the canvas is ethylene-based.
Propylene-diene terpolymer rubber or ethylene-
The belt main body is formed of propylene rubber as a main rubber, and the belt body is formed of a rubber composition containing ethylene-propylene-diene terpolymer rubber or ethylene-propylene rubber as a main rubber, and a connection between the canvases exposed on the canvas surface. The power transmission belt, wherein the portion is formed by joining the ends of the canvas with each other.