JP2009127816A - Toothed belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of dedendum portions while maintaining the bending property of a toothed belt. <P>SOLUTION: The toothed belt 10 includes a tooth rubber layer 11 and a back rubber layer 12. The tooth rubber layer 11 includes tooth portions 14 and tooth bottom portions alternately formed along the longitudinal direction of the belt. The tooth rubber layer 11 consists of a surface tooth rubber layer 16 provided on the tooth surface side, and an adhesive rubber layer 17 provided on the side of the back rubber layer 12. Between the adhesive rubber layer 17 and the back rubber layer 12, core wires 30 are embedded extending in the longitudinal direction in crosswise spaced relation. Part of the adhesive rubber layer 17 is formed running over from between the core wires 30 to the side of the back rubber layer 12 to form run-over portions 18. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a toothed belt used in a high load environment, for example.

  A toothed belt is widely used as a belt for transmitting power in internal combustion engines and various devices for general industrial use. In recent years, internal combustion engines and various devices have been miniaturized, and accordingly, toothed belts are also being miniaturized. As a result, high loads are applied to the toothed belts. When a high load is applied to the toothed belt, a high stress is applied to the root portion, and there is a problem in that tooth missing occurs early on the root portion.

  Conventionally, as described in Patent Document 1, for example, a toothed belt in which an adhesive rubber layer is provided between a tooth rubber layer and a back rubber layer and a core wire is embedded in the adhesive rubber layer is known. In this toothed belt, short fibers are mixed in the adhesive rubber layer, whereby the rigidity of the tooth base portion is increased and early tooth chipping is prevented.

When manufacturing the above-mentioned toothed belt, a pre-formed canvas in which a tooth rubber sheet is joined to a canvas that has been previously formed into a tooth shape is prepared. Then, a preformed canvas, a core wire, an adhesive rubber sheet, and a back rubber sheet are wound around the mold of the vulcanizing pot in this order, and then vulcanized and molded by pressing and heating to produce a toothed belt. In this manufacturing process, the adhesive rubber sheet is pressed inward from the back side, flows into the inside through the core wires, and is integrally bonded to the tooth rubber layer. The core wire is buried in
JP 2005-180486 A

  However, according to the toothed belt described in Patent Document 1, since the adhesive rubber layer is pushed from the back side and flows into the tooth rubber layer side, the thickness of the adhesive rubber layer on the back side from the core wire is small. Relatively thick. Therefore, the belt rigidity on the back side is increased, and the flexibility of the belt may be impaired.

  In particular, since the thickness of the adhesive rubber layer is uniformly formed on the back side from the core wire, the thickness is increased in both the tooth portion and the root portion, and not only the tooth root portion of the tooth portion. The tooth bottom part also becomes less flexible. However, when the belt is bent, the relatively thin-walled tooth bottom portion is bent greatly, so that if the flexibility of the tooth bottom portion is low, cracks are likely to occur in the tooth bottom portion.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a toothed belt having high flexibility while increasing the rigidity of the root portion of the belt.

  The toothed belt according to the present invention includes a tooth rubber layer in which tooth portions and a tooth bottom portion are alternately formed on one surface along the longitudinal direction of the belt, and a back rubber layer provided on the other surface of the tooth rubber layer. A core wire extending in the longitudinal direction of the belt and embedded in the width direction at a boundary portion between the back rubber layer and the tooth rubber layer, and a part of the tooth rubber layer is It is formed so as to protrude from the space to the back rubber layer side, and constitutes a protruding portion.

  It is preferable that the volume per unit length along the belt longitudinal direction of the protruding portion is relatively small at the tooth bottom portion and relatively large at the tooth portion. Further, it is preferable that the protruding portion is formed to swell larger than the interval between the core wires, and is in close contact with the surface of the core wire on the back rubber layer side.

  The tooth rubber layer is preferably provided with a surface tooth rubber layer provided on one surface side and an adhesive rubber layer provided on the back rubber layer side. In this case, at least a part of the adhesive rubber layer constitutes the protruding portion.

  The modulus of the adhesive rubber layer should be larger than that of the surface tooth rubber layer. For example, short fibers are mixed in the adhesive rubber layer. Furthermore, it is preferable that the surface tooth rubber layer contains short fibers having a smaller modulus than the short fibers mixed in the adhesive rubber layer.

  The method for manufacturing a toothed belt according to the present invention includes a tooth rubber sheet formed on a jacket formed in advance along a tooth shape in a toothed mold formed in a tooth shape by arranging a plurality of tooth grooves in the circumferential direction on the outer periphery. A pre-molded jacket attaching step for attaching a pre-formed jacket to which a wire is bonded to a toothed mold, and a core wire winding step for winding a core wire on a tooth rubber sheet in a circumferential direction so that adjacent core wires are separated from each other And a rubber attaching process for attaching the back rubber sheet on the core wire, urging the pressure inward from the back rubber sheet side, and heating at least the tooth rubber sheet and the back rubber sheet. A vulcanization step of forming a belt sleeve by vulcanization, and in the vulcanization step, a portion of the tooth rubber sheet is relatively between the adjacent core wires and relative to the core wire. Allowed to flow out to the side, and forming a protruding portion.

  The tooth rubber sheet preferably includes a surface tooth rubber sheet bonded to the canvas and an adhesive rubber sheet attached on the surface tooth rubber sheet. In this case, the protruding portion is formed by the adhesive rubber sheet.

  The present invention provides a toothed belt having high flexibility while increasing the rigidity of the root portion of the belt by providing a protruding portion that protrudes from the tooth rubber layer side to the back rubber layer side. be able to.

The present invention will be described below with reference to the drawings.
FIG. 1 shows a toothed belt 10 according to an embodiment of the present invention. The toothed belt 10 is an endless belt, and a belt main body 13 is integrally formed by the tooth rubber layer 11 and the back rubber layer 12.

  The tooth rubber layer 11 has tooth portions 14 and tooth bottom portions 15 alternately formed along the longitudinal direction on one surface (tooth surface 11A) side. The tooth surface 11 </ b> A of the tooth rubber layer 11 is covered with the canvas 20. The back rubber layer 12 is provided in close contact with the tooth rubber layer 11 on the other surface side of the tooth rubber layer 11. A core wire 30 that is wound in a spiral shape and extends in the longitudinal direction of the belt is embedded in a boundary portion between the tooth rubber layer 11 and the back rubber layer 12.

  The tooth rubber layer 11 includes a surface tooth rubber layer 16 provided on the tooth surface 11A side and an adhesive rubber layer 17 provided on the other surface side (back rubber layer 12 side), which are integrally formed, The surface tooth rubber layer 16 is bonded to the back rubber layer 12 via the adhesive rubber layer 17. The surface tooth rubber layer 16 is recessed toward the tooth surface 11 </ b> A side at the center of the tooth portion 14, and an adhesive rubber layer 17 is filled in the recessed portion. A part of the adhesive rubber layer 17 extends beyond the core wire 30 and protrudes to the back rubber layer 12 side to form a protruding portion 18.

  The surface tooth rubber layer 16, the adhesive rubber layer 17, and the back rubber layer 12 are obtained by vulcanizing a predetermined rubber component that is appropriately mixed with an additive. Examples of the rubber component include hydrogenated nitrile rubber (H-NBR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPDM), millable urethane, fluorine rubber, silicon rubber, or a mixture thereof. Is used, but H-NBR is preferably used. The same rubber component may be used as the rubber component of each rubber layer 16, 17, 12 or different rubber components may be used. Moreover, the same additive may be used for the rubber component of each rubber layer, or different additives may be used.

  The surface tooth rubber layer 16 and the adhesive rubber layer 17 are mixed with countless short fibers 40 and 41, respectively, while the back rubber layer 12 is not mixed with short fibers. The short fiber 40 mixed in the surface tooth rubber layer 16 is a short fiber whose modulus is lower than that of the short fiber 41 mixed in the adhesive rubber layer 17 and is, for example, a nylon short fiber, preferably a modified nylon microfiber. The modified nylon microfiber is made of, for example, a copolymer obtained by graft copolymerizing polyolefin with nylon fiber. The short fibers 41 mixed in the adhesive rubber layer 17 are, for example, aramid short fibers.

  However, the short fibers 40 and 41 can also use short fibers other than the types described above. For example, synthetic fibers such as glass fibers and polyester fibers, and natural fibers such as cotton can also be used. . Further, the surface tooth rubber layer 16 may not contain short fibers.

  When the short fibers 40 mixed in the surface tooth rubber layer 16 are modified nylon microfibers, the short fibers 40 are randomly oriented in the surface tooth rubber layer 16. However, when the short fibers 40 are other types of short fibers, they may be oriented in a predetermined direction. On the other hand, the short fibers 41 mixed in the adhesive rubber layer 17 are oriented substantially along the thickness direction of the belt.

  The adhesive rubber layer 17 is blended with short fibers having a high modulus, so that the modulus is higher than that of the surface tooth rubber layer 16 and the back rubber layer 12, and the modulus is, for example, 8 MPa or more. Since the short rubber is not mixed in the back rubber layer 12, the modulus is lower than that of the surface tooth rubber layer 16, and the modulus is, for example, less than 4 MPa. In addition, the modulus of the surface tooth rubber layer 16 is, for example, 1 to 9 MPa. The modulus of each rubber layer refers to a measurement sample obtained by vulcanizing each rubber sheet described below under the same temperature and time conditions as in the method for manufacturing a toothed belt, for example, in accordance with JIS-K6251. The measured 20% modulus. In addition, when the short fibers are oriented in a predetermined direction in each rubber layer, the modulus is measured when the short fibers are oriented in one direction in the sample and the sample is pulled in the orientation direction. Value.

  2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. As shown in FIGS. 2 and 3, the core wire 30 wound in a spiral shape is separated from the adjacent core wire 30 in the width direction. Further, a part of the adhesive rubber layer 17 is formed so as to protrude to the back rubber layer 12 side from between the core wires 30 adjacent to each other in the width direction, and constitutes a protruding portion 18. Each protruding portion 18 swells in the width direction larger than the interval W between the adjacent core wires 30, and surrounds a part of the core wire 30 while being in close contact with a part of the surface of the core wire 30. Thereby, a part of each core wire 30 is sandwiched between the protruding portion 18 and the adhesive rubber layer 17.

  As shown in FIG. 1, the protruding volume per unit length along the belt longitudinal direction of each protruding portion 18 is relatively small at the tooth bottom portion 15 and relatively large at the tooth portion 14. That is, as shown in FIGS. 2 and 3, the protruding portion 18 has a thickness L that is relatively large in the tooth portion 14 and relatively small in the tooth bottom portion 15, and is the most rear side in the central portion of the tooth portion 14. Stick out.

  4-7 is a figure for demonstrating the manufacturing method of the toothed belt which concerns on this embodiment. In the manufacture of the toothed belt 10, first, the preforming drum 51 is used to produce the preformed jacket 50.

  As shown in FIG. 4, the outer periphery of the preforming drum 51 is provided with tooth grooves 52 and convex portions 55 alternately in the circumferential direction, and a toothed roller 53 is engaged with a part of the outer periphery. The toothed roller 53 is provided with a tooth portion 54 that cooperates with the tooth groove 52 of the preforming drum 51. The pre-forming drum 51 and the toothed roller 53 are rotated in directions indicated by arrows A and B, respectively.

  The canvas 20 is supplied to the pre-forming drum 51 so as to surround a part of the outer periphery of the pre-forming drum 51 and is introduced into an engagement region with the toothed roller 53. Here, the canvas 20 is preformed into a corrugated shape in which the concave portions 20A and the convex portions 20B are alternately formed by the cooperative action of both the convex portions 55 and the tooth portions 54.

  As shown in FIG. 5, a steel band 57 is caused to travel at the same speed as the peripheral speed of the preforming drum 51 with an appropriate pressing force on a part of the outer periphery of the preforming drum 51. A surface tooth rubber sheet 16 ′ and an adhesive rubber sheet 17 ′ are stacked between the preforming drum 51 and the steel band 57 and supplied as a tooth rubber sheet 11 ′. Further, the preformed canvas 20 is also supplied to the lower side of the steel band 57 in a state of being wrapped around the outer periphery of the preforming drum 51.

  Between the preforming drum 51 and the steel band 57, the tooth rubber sheet 11 ′ is laminated and integrated on the pre-formed canvas 20, and the pre-molding is performed by joining the tooth rubber sheet 11 ′ to the canvas 20. A jacket 50 is obtained. The surface tooth rubber sheet 16 ′ and the adhesive rubber sheet 17 ′ are respectively formed into the surface tooth rubber layer 16 and the adhesive rubber layer 17 in the post-vulcanization toothed belt 10. Short fibers 40 are randomly oriented and mixed in the surface tooth rubber sheet 16 ′, and short fibers 41 are oriented in the circumferential direction in the adhesive rubber sheet 17 ′.

  Due to the pressing of the steel band 57, the rubber sheets 16 ′ and 17 ′ in the preformed jacket 50 are deformed along the unevenness of the canvas 20, are relatively thick inside the concave portion 20A, and are relatively thick on the convex portion 20B. getting thin. As a result, tooth portions 14 ′ and tooth bottom portions 15 ′ are alternately formed on the preformed jacket 50.

  Further, the tooth surface rubber sheet 16 ′ is recessed on the inner side of the drum so as to conform to the shape of the canvas 20 at the center portion of the tooth portion 14 ′ to form a recess 16 </ b> A. Then, the adhesive rubber sheet 17 ′ is deformed so as to be inclined inward with respect to the circumferential direction of the drum, and is filled in the recess 16 A. Therefore, a large number of short fibers 41 mixed in the adhesive rubber sheet 17 ′ are oriented inwardly with respect to the circumferential direction in accordance with the inclination, and in the vicinity of the tip portion inside the recess 16A with respect to the circumferential direction. In a substantially vertical direction (belt thickness direction).

  The preformed jacket 50 is sequentially cut to a predetermined length, and then wound around the outer periphery of a cylindrical toothed mold 60 so that the canvas 20 side faces inward as shown in FIG. The toothed mold 60 is formed in a tooth shape by arranging a plurality of tooth grooves 61 at equal intervals in the circumferential direction on the outer peripheral surface thereof. The preformed jacket 50 is preformed so as to follow the tooth profile of the toothed mold 60. Therefore, when the preformed jacket 50 is wound around the toothed mold 60, the tooth portion 14 ′ is disposed in the tooth gap 61 and the tooth bottom portion 15 ′ is disposed on the convex portion 62 between the tooth grooves 61. Is done. The volume of the tooth portion 14 ′ is larger than the volume inside the tooth groove 61 of the portion used for belt molding, and the tooth portion 14 ′ overflows from the inside of the tooth groove 61 to the outer peripheral side.

  Subsequently, the core wire 30 is wound around the preformed jacket 50 (that is, the adhesive rubber sheet 17 ′) in a spiral shape along the circumferential direction so that the adjacent core wires 30 have a predetermined gap therebetween. Next, a back rubber sheet 12 ′ which becomes the back rubber layer 12 of vulcanization molding is further wound around the core wire 30.

  The toothed mold 60 to which these rubber sheets and the like are attached is accommodated in a vulcanizer (not shown). The inside of the vulcanizing vessel is maintained in a state heated to a predetermined temperature by, for example, steam, and pressure is applied from the outer peripheral side of the mold 60 toward the inner peripheral side by a vulcanizing bag or the like provided in the vulcanizing vessel. Is done. By the steam heating, the rubber sheets 11 ′ and 12 ′ are increased in fluidity, and the canvas 20, the rubber sheets 11 ′ and 12 ′, and the core wire 30 are pressed inward by pressurization. Accordingly, the canvas 30 is formed into a shape that matches the outer peripheral shape of the toothed mold 60, and the tooth rubber sheet 11 ′ is also flown inward along the canvas 30.

  Here, the volume of each tooth portion 14 ′ in the preformed jacket 50 is larger than the volume inside each tooth groove 61, and the adhesive rubber sheet 17 ′ overflows from the tooth groove 61. Therefore, when the core wire 30 is moved inward by pressurization, a part of the adhesive rubber sheet 17 ′ cannot enter the tooth gap 61, and the core is released from the gap formed between the adjacent core wires 30. It will flow out toward the outside relative to the line 30. A part of the adhesive rubber sheet 17 ′ that has flowed out forms a protruding portion 18 as shown in FIG. 7.

  As described above, the adhesive rubber sheet 17 'in the tooth portion 14' is thicker than the adhesive rubber sheet 17 'in the tooth bottom portion 15'. Therefore, the amount of the adhesive rubber sheet 17 ′ flowing out toward the outside of the core wire 30 is relatively large at the tooth portion 14 ′ and relatively small at the tooth bottom portion 15 ′. Accordingly, the thickness L of the protruding portion 18 is relatively large at the tooth portion 14 ′, while it is relatively small at the tooth bottom portion 15 ′.

  Further, when the adhesive rubber sheet 17 ′ flows relatively outward, the short fibers 41 are also flowed outward, and the longitudinal direction of the short fibers 41 is directed in the flowing direction in accordance with the flow of the adhesive rubber sheet 17 ′. . Accordingly, in the adhesive rubber sheet 17 ′, the short fibers 41 other than the short fibers 41 near the tip of the recess 16A that have already been oriented in the thickness direction of the belt are also in the thickness direction of the belt of the rubber sheet 17 ′. Oriented.

  As the pressurization and heating proceed, the rubber sheets 16 ', 17' and 12 'are vulcanized, and the surface tooth rubber sheet 16' and the back rubber sheet 12 'are vulcanized and bonded via the adhesive rubber sheet 17'. It is done. At the same time, the surface tooth rubber sheet 16 ′ is vulcanized and bonded to the canvas 20, thereby obtaining a vulcanized belt slab 10 ′. The belt slab 10 ′ is removed from the toothed drum 60 and cut after polishing, whereby the toothed belt 10 (see FIG. 1) is obtained.

  As described above, in the present embodiment, in the toothed belt 10, the core wire 30 is surrounded by the adhesive rubber layer 17 having relatively high rigidity. Therefore, the strength of the root portion of the toothed belt is improved, and breakage due to tooth chipping or the like of the toothed belt is effectively prevented. In addition, the adhesive rubber layer 17 having a relatively high rigidity is formed thick at the tooth portion 14 and thin at the tooth bottom portion 15, and the flexibility of the tooth bottom portion 15 becomes relatively good. Therefore, the belt is bent and attached when the belt is attached to the pulley, and accordingly, the bottom portion 15 of the belt is largely bent. However, the bending does not cause cracks or the like in the bottom portion 15.

  Further, the belt thickness direction in which the short fibers of the adhesive rubber layer are oriented is the same as the load direction acting on the tooth root portion of the belt when the belt rotates, thereby improving the durability of the belt. Furthermore, since no short fibers are mixed in the back rubber layer, cracks from the back rubber are unlikely to occur. Furthermore, in this embodiment, since the core wire is surrounded by the high modulus adhesive rubber layer, the adhesive strength between the adhesive rubber layer and the core wire can be increased by the anchor effect. On the other hand, since the modulus of the surface tooth rubber layer is relatively low, the generation of cracks on the tooth surface and the generation of noise during meshing with the pulley are prevented.

It is a side view of a toothed belt concerning one embodiment concerning the present invention. It is a cross-sectional view which follows the II-II line in FIG. It is a cross-sectional view along the III-III line in FIG. It is a longitudinal cross-sectional view which shows a mode that a canvas is preformed. It is a longitudinal cross-sectional view which shows a mode that a tooth rubber sheet is joined to the preformed canvas. It is a longitudinal cross-sectional view which shows a mode when a preforming jacket, a core wire, and a back rubber sheet are attached to a toothed mold. It is a longitudinal cross-sectional view which shows the mode of the toothed mold after vulcanization molding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Toothed belt 11 Tooth rubber layer 12 Back rubber layer 14 Tooth part 15 Tooth bottom part 16 Surface tooth rubber layer 17 Adhesive rubber layer 18 Overhang part 20 Canvas (jacket)
30 Core 40, 41 Short fiber 50 Pre-molded jacket 11 'Tooth rubber sheet 12' Back rubber sheet 16 'Surface tooth rubber sheet 17' Adhesive rubber sheet

Claims (9)

A tooth rubber layer in which tooth portions and tooth bottom portions are alternately formed along the longitudinal direction of the belt on one surface;
A back rubber layer provided on the other surface of the tooth rubber layer;
A core wire that extends in the longitudinal direction of the belt at the boundary portion between the back rubber layer and the tooth rubber layer and is embedded separately in the width direction,
A portion of the tooth rubber layer is formed so as to protrude from between the core wires to the back rubber layer side, and constitutes a protruding portion.   2. The toothed belt according to claim 1, wherein a volume per unit length along the belt longitudinal direction of the protruding portion is relatively small in the tooth bottom portion and relatively large in the tooth portion. .   2. The toothed belt according to claim 1, wherein the protruding portion is formed to swell larger than an interval between the core wires, and is in close contact with the surface of the core wire on the back rubber layer side. The tooth rubber layer comprises a surface tooth rubber layer provided on the one surface side, and an adhesive rubber layer provided on the back rubber layer side,
The toothed belt according to claim 1, wherein at least a part of the adhesive rubber layer constitutes the protruding portion.   The toothed belt according to claim 4, wherein a modulus of the adhesive rubber layer is larger than a modulus of the surface tooth rubber layer.   The toothed belt according to claim 5, wherein short fibers are mixed in the adhesive rubber layer.   The toothed belt according to claim 6, wherein the surface tooth rubber layer is mixed with short fibers having a modulus smaller than that of the short fibers mixed in the adhesive rubber layer. A plurality of tooth grooves on the outer periphery are arranged in the circumferential direction, so that a pre-molded jacket in which a tooth rubber sheet is joined to a pre-molded jacket along the tooth profile is added to the tooth mold formed in the tooth profile. A pre-molding jacket attaching process to be attached to the mold;
On the tooth rubber sheet, the core wire is wound in the circumferential direction so that adjacent core wires are separated from each other, and
A rubber attaching step of attaching a back rubber sheet on the core wire;
While urging the pressure inward from the back rubber sheet side, and at least heating the tooth rubber sheet and the back rubber sheet, vulcanizing them to form a belt sleeve,
In the vulcanization step, a part of the tooth rubber sheet is caused to flow out from between the adjacent core wires to the outside relative to the core wire, thereby forming a protruding portion. A method for manufacturing a belt.   The tooth rubber sheet includes a surface tooth rubber sheet bonded to the canvas and an adhesive rubber sheet attached on the surface tooth rubber sheet, and the protruding portion is formed by the adhesive rubber sheet. A method for manufacturing a toothed belt according to claim 8.

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