JP2010210088A - Toothed belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toothed belt that is excellent in durability so that it can reliably protect a canvas and a toothed portion even if used over a long period under severe conditions where high loads are applied at high temperatures. <P>SOLUTION: A tooth rubber layer 12 of the toothed belt 10 is covered with a tooth surface canvas 18 and the outermost tooth surface protection layer 20. The tooth surface protection layer 20 is formed of a rubber sheet. The outside of the tooth surface canvas 18 is covered with the tooth surface protection layer 20 to keep shock absorption good while improving wear resistance, etc. Further, short fibers 24 are added to harden the tooth rubber layer 12 to increase the rigidity of the entire toothed portion to improve the durability of the toothed belt 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a toothed belt used in an automobile engine or the like.

  Toothed belts are widely used in automobile engines and the like. Due to the narrowing accompanying the downsizing of automobile engines, the toothed belt is required to have durability enough to withstand a high load.

  In order to improve the durability of the toothed belt, the canvas is treated (for example, see Patent Document 1), or a layer made of plastomer and elastomer is adhered to the tooth surface (for example, see Patent Document 2). Are known.

JP 2000-240730 A JP 2002-39276 A

  There is a possibility that the durability of the toothed belt cannot be sufficiently improved by the RFL treatment or the rubber paste treatment on the canvas covering the tooth surface. For example, even if the canvas is treated in this manner, the frictional resistance is not sufficiently improved, and as a result, there is a possibility that tooth missing may occur. Further, in a toothed belt used at a high temperature such as around the engine, the amount of deformation of the tooth portion becomes particularly large, which may cause deterioration due to internal heat generation and occurrence of cracks in the tooth root portion.

  Even when an adhesive layer made of plastomer and elastomer is provided on the surface of the tooth portion, there is a possibility that sufficient durability may not be obtained. This is because the adhesive layer does not have sufficient durability due to containing a large amount of the plastomer component, or can be peeled off from the adhesive surface.

  In addition, it is conceivable to improve the durability of the toothed belt by simply increasing the hardness of the teeth covered with the canvas, but cracks are likely to occur relatively early due to stress concentration in the canvas.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to realize a toothed belt excellent in durability that can reliably protect a canvas and a tooth part even when used under a severe condition such as a high load applied at a high temperature. .

  The toothed belt of the present invention includes a tooth portion formed of an elastomer and a tooth surface canvas that covers the surface of the tooth portion, and further includes a tooth surface protection layer formed of a rubber sheet provided outside the tooth surface canvas. It is characterized by that. The tooth surface protective layer preferably contains fluorine rubber or HNBR (hydrogenated nitrile rubber), and more preferably contains both fluorine rubber and HNBR.

  The ratio of the thickness of the tooth surface protective layer to the thickness of the tooth portion is preferably 0.03 to 0.20. The toothed belt preferably further has a reinforcing material for improving the hardness of the tooth portion. Moreover, it is preferable that a toothed belt further has the back surface protective layer by the rubber sheet provided in the back surface. In this case, it is more preferable that the back canvas is laminated inside the back protective layer.

  The thickness of the tooth surface protective layer is, for example, 0.1 to 0.5 mm. In addition, the toothed belt includes a pre-molding process in which a tooth surface molded body having a shape corresponding to the tooth surface is formed after the tooth surface canvas and the tooth surface protective layer are pressure-bonded, and a process after the pre-molding process. It is preferable to manufacture by a sulfur process.

  The method for manufacturing a toothed belt according to the present invention includes a first pre-forming step of pressing a tooth surface canvas and a tooth surface protective layer to form a corrugated shape to obtain a tooth surface molded body, and forming a tooth portion of the belt. A tooth rubber layer to be laminated on the tooth surface canvas side of the tooth surface molded body to obtain a tooth portion molded body, and the tooth surface molded body, the tooth surface protective layer is disposed inside As described above, after the first mounting step of mounting on the molding die, the second mounting step of mounting the core wire and the back rubber layer on the outside of the tooth part molded body on the molding die, and after the second mounting step And a vulcanization step of obtaining a belt slab by vulcanization molding.

  ADVANTAGE OF THE INVENTION According to this invention, even if it uses for a long time under severe conditions, such as high load is applied under high temperature, the toothed belt excellent in durability which can protect a canvas and a tooth | gear part reliably can be implement | achieved.

It is a perspective view which fractures | ruptures and shows a part of toothed belt of 1st Embodiment. It is sectional drawing which shows the pre-molding process made into the shape according to the surface of a tooth | gear part, after crimping | bonding a tooth surface canvas and a tooth surface protective layer. It is sectional drawing which shows the pre-molding process which pushes a material member into a tooth surface molded object, and forms a tooth part molded object. It is a perspective view which fractures | ruptures and shows a part of toothed belt of 2nd Embodiment. It is a perspective view which fractures | ruptures and shows a part of toothed belt of 3rd Embodiment. It is a figure which shows the outline | summary of a servo pulsar test. It is a figure which shows the result of the servo pulser test in the toothed belt of an Example and a comparative example.

  Hereinafter, the toothed belt of the first embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing a part of the toothed belt according to the first embodiment in a cutaway manner.

  The toothed belt 10 includes a tooth rubber layer 12, a back rubber layer 14, a tooth surface canvas 18, and a tooth surface protective layer 20 provided with a plurality of tooth portions 12A along the length. The outer surface of the tooth rubber layer 12 is covered with a tooth surface canvas 18. Furthermore, a tooth surface protective layer 20 of a rubber sheet is provided on the outside of the tooth surface canvas 18, that is, on the tooth surface of the toothed belt 10. A plurality of core wires 16 parallel to the longitudinal direction of the toothed belt 10 are embedded between the tooth rubber layer 12 and the back rubber layer 14.

  The tooth rubber layer 12 includes aramid short fibers 24 (reinforcing material). The tooth rubber layer 12 preferably contains a large amount of short fibers to increase the hardness as much as possible. Specifically, the short fiber 24 is added, for example, 1 to 36 parts by weight, preferably 12 to 24 parts by weight with respect to 100 parts by weight of the rubber component of the tooth rubber layer 12.

  The short fibers 24 are arranged so as to be substantially along the longitudinal direction of the toothed belt 10 and to correspond to the surface shape of the tooth rubber layer 12. The tooth rubber layer 12 is reinforced by short fibers 24 and has increased hardness. The hardness of the tooth rubber layer 12 is, for example, 85-100. The hardness is measured with a type A durometer (A type) of JIS K 6253.

  The tooth surface protective layer 20 is preferably formed of HNBR, fluororubber, or a mixture of HNBR and fluororubber. When the toothed belt 10 is used in an environment where oil adheres, the tooth surface protective layer 20 should preferably contain fluororubber in order to improve the oil resistance of the belt. In this case, the tooth surface protective layer 20 is more preferably formed of a mixture of HNBR and fluororubber in order to improve the adhesion to the tooth surface canvas 18 and improve the durability of the belt. On the other hand, when the toothed belt 10 is used in an environment where oil does not adhere, the tooth surface protective layer 20 should preferably be formed of HNBR alone without containing fluororubber.

  When the tooth surface protective layer 20 is formed of a mixture of HNBR and fluororubber, the weight ratio of HNBR: fluororubber is 90:10 to 10:90, preferably 70:30 to 30:70. By setting the weight ratio within these ranges, it is possible to improve the oil resistance of the belt while improving the adhesion to the tooth surface canvas 18.

  The hardness of the tooth surface protective layer 20 is, for example, 60 to 100. Further, the tooth surface protective layer 20 is preferably one in which short fibers are not mixed in order to ensure a certain level of shock absorption. The tooth surface canvas 18 is formed of, for example, an aramid fiber, but may be formed of other materials.

  The ratio (D2 / D1) of the thickness D2 of the tooth surface protective layer 20 to the thickness D1 of the tooth portion 12A is, for example, 0.03 to 0.20. However, the thickness ratio (D2 / D1) is preferably 0.05 to 0.13. By setting the thickness ratio in such a range, it is possible to keep the tooth portion in good strength while improving the impact absorption of the tooth surface. Furthermore, the thickness ratio (D2 / D1) is more preferably 0.08 to 0.10. By setting it as such a range, durability of a belt, especially the durability of the belt at the time of high load action can be further improved.

  The thickness D2 of the tooth surface protective layer 20 is approximately in the range of 0.1 mm to 0.5 mm, for example, about 0.2 mm to 0.3 mm. The thickness D1 of the tooth portion 12A is the thickness of the tooth rubber layer 12 in the portion where the tooth tip is provided, as is apparent from FIG.

  The back rubber layer 14 and the tooth rubber layer 12 are formed of, for example, HNBR. When formed of HNBR, it is preferable that a metal carboxylate is added to the back rubber layer 14 and the tooth rubber layer 12 in order to improve the adhesion of the rubber layer to the canvas and the core wire. In addition, when the tooth surface protective layer 20 includes HNBR, the carboxylic acid metal salt may be added to the tooth surface protective layer 20.

  In the present embodiment, the provision of the tooth surface protective layer 20 made of a relatively hard and thick rubber sheet improves the durability of the tooth surface of the toothed belt 10, that is, wear resistance, heat resistance, and the like.

  Furthermore, a tooth surface protective layer 20 for improving the durability of the tooth surface is provided in the outermost layer, and the tooth surface canvas 18 is disposed under the tooth surface protective layer 20. By disposing the tooth surface protective layer 20 and the tooth surface canvas 18 in this way, it is possible to improve the shock absorption.

  As described above, according to the present embodiment, a severe load is applied such that a high load is applied at a high temperature mainly by covering the tooth surface with the tooth surface protective layer 20 of the rubber sheet and increasing the hardness of the tooth rubber layer 12. The durability of the toothed belt 10 is improved even under conditions, and the toothed belt 10 can be used normally over a long period of time. Moreover, since the core wire 16 is covered with the hard rubber layer (tooth rubber layer 12), it is possible to prevent the rubber layer from being peeled off at the interface with the core wire 16 due to the anchor effect.

  Next, a manufacturing method of the toothed belt 10 will be described. FIG. 2 is a cross-sectional view showing a pre-molding step for forming a tooth surface forming body having a shape corresponding to the surface of the tooth portion after the tooth surface canvas 18 and the tooth surface protective layer 20 are pressure-bonded. FIG. 3 is a cross-sectional view showing a pre-molding process in which a material member is pushed into a tooth surface molded body to form a tooth portion molded body.

  First, in order to enhance the adhesion between the canvas 18 and the tooth surface protective layer 20 on the tooth surface canvas 18 as necessary, an isocyanate adhesion treatment, a dipping treatment in a resorcin-formalin-latex solution (RFL treatment), a rubber paste Pre-processing such as processing is performed. After this treatment, the tooth surface canvas 18 and the tooth surface protective layer 20 are laminated and pressed. The tooth surface canvas 18 and the tooth surface protective layer 20 in a state of being overlapped in this way are continuously fed onto the preforming drum 32. On the surface of the preforming drum 32, tooth spaces 52 are provided at a predetermined pitch. The preforming drum 32 rotates in the direction indicated by the arrow A.

  Further, the toothed roller 34 is rotated in the direction of arrow B in conjunction with the pre-forming drum 32. The laminated tooth surface canvas 18 and the tooth surface protective layer 20 move in the direction indicated by the arrow A together with the preforming drum 32. In the region where the pre-forming drum 32 and the toothed roller 34 are engaged, the tooth surface canvas 18 and the tooth surface are obtained by the cooperative action of the tooth portion 36 of the pre-forming drum 32 and the tooth portion 38 of the toothed roller 34. The protective layer 20 is deformed. As a result, the tooth surface canvas 18 and the tooth surface protective layer 20 are formed into a corrugated shape similar to the surface shape of the tooth rubber layer 12 shown in FIG.

  Subsequently, the material member 13 (see FIG. 3) of the tooth rubber layer 12 made of an elastomer such as HNBR (hydrogenated nitrile rubber) including the short fibers 24 is laminated on the tooth surface canvas 18 of the tooth surface molded body 42. The material member 13 is pressed in the direction indicated by the arrow C and pressed into the tooth groove 52 of the pre-molding drum 32 to be integrated with the tooth surface molded body 42 to form a tooth portion molded body 45.

  This tooth part molded body 45 is cut into a predetermined length and mounted on a molding die (not shown). At this time, the tooth surface protective layer 20 is disposed on the molding die side, that is, on the inner side. Then, the core wire 16 is wound on the tooth portion molded body 45, and further, the material member of the back rubber layer 14 is laminated on the core wire 16 to form a toothed belt intermediate (none of which is shown). .

  The toothed belt intermediate disposed on the molding die is pressurized and heated (vulcanization step). The vulcanized tooth rubber layer material and the back rubber layer material are deformed in this way, and a belt slab (not shown) having the same cross-sectional shape as the toothed belt 10 is formed. The slab is cooled and cut into a circular shape so as to have a predetermined width. As a result, the toothed belt 10 is manufactured.

  In the present embodiment, since it is difficult to deform the rubber sheet, which is the material of the tooth surface protective layer 20, into a tooth surface shape only by the vulcanization step, a pre-molding step is provided. However, when rubber with good flowability is used as the material for the tooth surface protective layer 20, the pre-molding step may be omitted and the slab may be formed only by the vulcanization step.

  In the vulcanization process, the material member 13 of the tooth rubber layer 12 is impregnated in the tooth surface canvas 18. The amount of impregnation of the material of the tooth rubber layer 12 may be adjusted as appropriate. For example, in order to prevent uneven thickness of the tooth surface protection layer 20 (see FIG. 1), impregnation of the tooth surface canvas 18 with the material of the tooth rubber layer 12 may be appropriately suppressed. On the contrary, the material of the tooth rubber layer 12 may be sufficiently infiltrated so as to come into contact with the tooth surface protective layer 20 through the tooth surface canvas 18 after completion of the belt and welded to the tooth surface protective layer 20. In this case, the durability of the tooth surface can be further improved as compared with a toothed belt or the like from which the surface protective sheet simply adhered to the tooth rubber layer can be peeled off.

  Next, a second embodiment will be described. FIG. 4 is a perspective view showing a part of the toothed belt according to the second embodiment in a cutaway manner.

  A back protective layer 30 of a rubber sheet is provided on the back of the toothed belt 10 of the present embodiment. Thus, by providing the back surface protective layer 30 covering the back surface, the durability including the heat resistance and oil resistance of the toothed belt 10 of the present embodiment can be improved as compared to the first embodiment. The thickness of the back surface protective layer 30 is generally in the range of 0.1 mm to 1.0 mm, similar to the tooth surface protective layer 20, for example, about 0.2 mm to 0.5 mm.

  Furthermore, not only the tooth rubber layer 12 but also the back rubber layer 14 includes aramid short fibers 24 (reinforcing material). For this reason, the back rubber layer 14 is reinforced by the short fibers 24, and the hardness may be increased. Therefore, the interface peeling between the rubber layer and the core wire can be more effectively prevented by the anchor effect of the back rubber layer 14 in addition to the tooth rubber layer 12. Further, since the back surface protective layer 30 is provided, it is possible to prevent cracks from occurring on the back rubber side starting from the short fibers of the back rubber layer 14.

  The back protective layer 30 is formed of fluororubber or a mixture of HNBR and fluororubber. The back protective layer 30 is preferably formed of a mixture of HNBR and fluororubber in order to improve the adhesion with the back rubber layer. The back rubber layer 14 may be formed of HNBR alone or may be formed of a mixture of HNBR and fluororubber.

 When the back protective layer 30 is formed of a mixture of HNBR and fluororubber, the weight ratio of HNBR: fluororubber is 90:10 to 10:90, preferably 70:30 to 30:70, respectively. By setting the weight ratio within these ranges, it is possible to improve the oil resistance of the belt while improving the adhesion to the back rubber layer 14. Also when the back rubber layer 14 is formed of a mixture of HNBR and fluororubber, the weight ratio thereof is preferably selected from the above range.

  In this embodiment, since the back surface protective layer 30 containing fluororubber is provided, the durability can be improved particularly when the belt is used in an environment where oil adheres.

  The manufacturing process of the toothed belt according to the present embodiment is performed by stacking a layer member to be the back protective layer 30 after completion together with a material member of the back rubber layer 14 on a molding die (not shown). Except for forming a body (none of which are shown), this is the same as the first embodiment.

  Next, the third embodiment will be described focusing on the differences from the second embodiment. FIG. 5 is a perspective view showing a part of the toothed belt according to the third embodiment in a cutaway manner.

  In the toothed belt 10 of this embodiment, a back canvas 28 is laminated inside the back protective layer 30 and between the back rubber layer 14 and the back protective layer 30. Thus, by providing the back canvas 28 that covers the outer surface of the back rubber layer 14, the durability of the toothed belt 10 can be further improved as compared with the second embodiment. This is because the back canvas 28 further increases the strength of the back surface of the belt, such as preventing the occurrence of cracks in the back rubber layer 14, and further improves the heat resistance and oil resistance. The back canvas 28 is a woven or knitted fabric having elasticity, and may be seamless or seamless. The back canvas 28 is formed of, for example, an aramid fiber, and the tooth surface canvas 18 and the back canvas 28 may be formed of the same material, but may be formed of different materials.

  In the manufacture of the toothed belt of this embodiment, the back canvas 28 is bonded in advance to a rubber sheet (not shown) that is a material of the back protective layer 30. Then, a canvas jacket obtained by cutting and joining them to a predetermined length is laminated on the material member of the back rubber layer 14 to form a toothed belt intermediate body (not shown).

  In each of the above embodiments, the material, shape, and the like of each member of the toothed belt 10 are not limited to those described above. For example, the tooth surface protective layer 20 may be formed of an elastomer or resin other than the above-described HNBR and fluororubber.

  Further, the tooth rubber layer 12 and the back rubber layer 14 may be formed of rubber other than HNBR or fluororubber, or a thermoplastic elastomer. Further, the reinforcing material included in the tooth rubber layer 12 is not limited to the aramid short fibers 24, and may be, for example, short fibers such as nylon other than aramid, silica, SHP which is a fine fiber, and the like. In the second and third embodiments, when the back protective layer 30 includes HNBR, a carboxylic acid metal salt may be added to the back protective layer 30.

  Next, although embodiment of this invention is described in detail using an Example, this invention is not limited to the Example shown below.

  First, in order to show the effect of forming a tooth surface rubber layer with a mixture of fluororubber and HNBR, the following peel test and oil resistance immersion test were performed.

[Peel test]
The adhesion of the canvas to the rubber was measured by a test according to JIS K 6256-1. In this test, first, a rubber sheet having a width of 25 mm, a length of 120 mm, and a thickness of 3 mm was subjected to RFL treatment on an aramid canvas by press heating at 160 ° C. and 4 to 5 MPa to obtain a test piece. . Table 1 shows the force required when the canvas was peeled from the rubber sheet at a speed of 50 mm / min.

[Oil resistance immersion test]
Under the test conditions according to JIS K6258, an oil resistance immersion test was carried out, and the results are shown in Table 1. IRM903 was used as the lubricating oil for testing, and rubber pieces having a width of 20 mm, a length of 30 mm, and a thickness of 2 mm were used. Moreover, it implemented by immersion temperature 140 degreeC and immersion time 72 hours.

  As is clear from Table 1, the rubber sheet and rubber piece used in the peel test and the oil-resistant immersion test were HNBR simple rubber, fluororubber (FKM) simple rubber, and a mixture of these rubbers. In the mixture, HNBR: FKM weight ratios of 70:30, 50:50, and 30:70 were used. In addition, what added the carboxylic acid metal salt was used as HNBR, and the vinylidene fluoride fluororubber was used as FKM.

  Next, the toothed belts of Examples 1 to 6 and Comparative Examples 1 to 3 were produced, and the durability of these toothed belts was evaluated by a servo pulser test.

[Example 1]
The toothed belt according to Example 1 corresponds to the second embodiment, and the tooth surface protective layer and the back surface protective layer are rubber sheets in which HNBR and FKM are mixed at a weight ratio of 50:50. Formed by. These rubber sheets did not contain short fibers. The tooth rubber layer is formed of an HNBR rubber sheet to which 16 parts by weight of aramid short fibers are added with respect to 100 parts by weight of HNBR (rubber component), and the back rubber layer is 100 parts by weight of HNBR (rubber component). On the other hand, a rubber sheet of HNBR to which 4 parts by weight of aramid short fibers were added was formed. Further, an aramid canvas subjected to RFL treatment was used as the tooth surface canvas, and a core made of glass fiber was used as the core. HNBR to which a carboxylic acid metal salt was added was used as HNBR used in each layer, and vinylidene fluoride-based fluororubber was used as FKM. In addition, the thickness before molding of the rubber sheet for forming the tooth surface protective layer, the tooth rubber layer, the back rubber layer, and the back surface protective layer is 0.2 mm, 1.5 mm, 0.5 mm, and 0.2 mm, respectively. there were. The belt tooth profile was a YU tooth profile, and the belt width was 13 mm.

[Example 2]
The toothed belt according to Example 2 corresponds to the third embodiment, except that a back canvas made of an aramid canvas is provided between the back rubber layer and the back protective layer. 1 was carried out.

[Example 3]
The tooth surface protective layer is formed of a rubber sheet whose rubber component is composed of HNBR alone, and does not include short fibers, and the back surface protective layer does not include short fibers, and the weight ratio of HNBR: FKM is 70:30. The same procedure as in Example 2 was performed except that the rubber sheet was formed from a FKM mixture.

[Example 4]
The tooth surface protective layer and the back surface protective layer were carried out in the same manner as in Example 1 except that the rubber component was made of a single FKM and was formed of a rubber sheet containing no short fibers.

[Example 5]
Implemented in the same manner as in Example 4 except that the tooth surface protective layer and the back rubber layer were formed of a rubber sheet of a mixture of HNBR and FKM that does not contain short fibers and the weight ratio of HNBR: FKM is 70:30. did.

[Example 6]
The tooth surface protective layer was carried out in the same manner as in Example 5 except that the tooth surface protective layer was formed of a rubber sheet of a mixture of HNBR and FKM having a weight ratio of HNBR: FKM of 30:70, which did not contain short fibers.

[Comparative Example 1]
Except for the fact that the structure of the tooth rubber layer is a two-layer structure in which a relatively soft HNBR is used for the outer layer and a harder HNBR is used for the inner layer, and the tooth surface protective layer and the back surface protective layer are not provided. This was carried out in the same manner as in Example 1. In addition, the thickness before shaping | molding of the rubber sheet for forming the outer layer of the tooth rubber layer of 2 layer structure, an inner layer, and a back rubber layer was 1.0 mm, 0.5 mm, and 1.5 mm, respectively.

[Comparative Example 2]
In Comparative Example 2, the tooth surface protective layer and the back surface protective layer were not provided, and the aramid short fibers mixed in the tooth rubber layer were 4 parts by weight with respect to 100 parts by weight of HNBR (rubber component). In the same manner as in Example 1. In addition, the thickness before shaping | molding of the rubber sheet for forming a tooth rubber layer and a back rubber layer was 1.5 mm and 1.5 mm, respectively.

[Comparative Example 3]
The rubber component is composed of a single FKM, and a back protective layer formed from a rubber sheet not containing short fibers is provided, and the back rubber layer contains 4 parts by weight of aramid short fibers with respect to 100 parts by weight of HNBR (rubber component). This was carried out in the same manner as in Comparative Example 2 except for the points. The thickness before molding of the rubber sheet for forming the tooth rubber layer, the back rubber layer, and the back protective layer was 1.5 mm, 0.5 mm, and 1.0 mm, respectively.

  FIG. 6 is a diagram showing an outline of the servo pulser test. FIG. 7 is a diagram showing the results of the servo pulser test of each of the above-described examples and comparative examples. The servo pulser test was performed by the servo pulser testing machine 40 as follows. The servo pulser testing machine 40 includes a metal tip 43 and a clamp 44 having an uneven shape corresponding to the tooth profile of the toothed belt.

  In the evaluation test, the test piece 46 which cut | disconnected the toothed belt of each Example and the comparative example, and extract | collected partially was used. The upper end of the test piece 46 is fixed to the fixing portion 48, and the lower end teeth 46 a are engaged with the metal tip 43. The lower ends of the metal tip 43 and the test piece 46 are sandwiched from the left and right by the clamp 44 so as not to move. The test was conducted in an air atmosphere at 120 ° C.

  A clamp 44 sandwiching the metal tip 43 and the test piece 46 was periodically loaded with a sine wave load from 0 to a predetermined upper limit in a downward direction, and the frequency of the sine wave was 1 Hz. By changing the upper limit value of the load within a range of 300 to 500 N / belt width 13 mm as shown in FIG. 7, each test piece 46 was tested a plurality of times. And the frequency | count (cycle number) of the sine wave until the fracture | rupture of the tooth | gear 46a was measured. The number of cycles for each load until the tooth 46a is broken is shown on the horizontal axis of FIG.

  As is clear from FIG. 7, compared with Comparative Examples 1 and 2 that show almost the same results, in Example 1, the number of cycles until breakage was large even when the load was increased. For example, when the upper limit of the load is 400 N / belt width 13 mm, in Comparative Examples 1 and 2, the test piece 46 broke at a cycle number of about 1000 to 2000, whereas in Example 1, up to the time of breakage. The number of cycles exceeded 70000. Thus, it was confirmed that the durability of the toothed belt 10 of Example 1 is superior to that of Comparative Examples 1 and 2.

  The reason for this is that the outer surface of the tooth surface canvas 18 in Example 1 was covered with a tooth surface protective layer 20 to maintain good shock absorption while improving wear resistance and the like, and the tooth rubber layer 12 was hardened. it is conceivable that. As described above, in the toothed belt 10 of the embodiment in which the rigidity of the entire tooth portion is high, the load resistance is improved, so the deformation of the tooth portion is small, and the generation of internal heat and cracks can be suppressed.

  On the other hand, in Comparative Example 1, the hardness of the entire tooth rubber layer is mainly increased by the hard HNBR while the shock absorption property to the impact applied to the tooth rubber layer through the canvas is secured by the soft HNBR, and the durability is increased. Yes. However, since soft HNBR is included, it is impossible to sufficiently increase the hardness of the entire tooth rubber layer as in the embodiment.

  Further, in Comparative Example 2 without the tooth surface protective layer 20 as in Comparative Example 1, the tooth rubber layer is formed of a uniform component of HNBR whose hardness is increased with short fibers. Thus, the comparative example 2 which lacks the member which absorbs the impact from the outside is inferior to the impact-absorbing property of the tooth rubber layer. Therefore, it is difficult to improve the durability comprehensively, such as preventing the early occurrence of cracks due to stress concentration in the canvas.

  That is, in Comparative Examples 1 and 2, making the entire tooth rubber layer hard is not compatible with maintaining shock absorption. Therefore, Comparative Examples 1 and 2 were inferior to Example 1 in durability. As in Example 1, Example 2 also had better durability than Comparative Examples 1 and 2.

  Further, in Example 3 in which the tooth surface protective layer was formed of HNBR alone, durability was improved as compared with Examples 1 and 2. On the other hand, Example 4 which formed both the tooth surface protective layer and the tooth surface protective layer by FKM single-piece | unit was inferior to Examples 1-3. From these results, it can be understood that, in an environment where oil does not adhere, it is better that the tooth surface protective layer contains HNBR, and it is more preferable to form HNBR alone. However, as is clear from the comparison with Comparative Examples 1 to 3, regarding Example 4, it can be understood that the durability was improved by providing the tooth surface protective layer.

  On the other hand, in Examples 5 and 6, although the back protective layer was formed of FKM alone, the durability was the same as or higher than those in Examples 1 to 3. This is because the durability and the structure of the tooth surface protection layer are more influenced by the composition and structure of the tooth surface protection layer than the back surface protection layer in terms of durability in a normal use environment (that is, in an environment where oil does not adhere). This is probably because the durability was not lowered by using the mixture.

  Next, the toothed belts of Examples 7 to 9 and Comparative Example 4 were produced, and the durability of these toothed belts was evaluated by a servo pulser test.

[Example 7]
The toothed belt according to Example 7 corresponds to the first embodiment. The tooth surface protective layer was formed of a rubber sheet having a rubber component made of HNBR alone and containing no short fibers. The tooth rubber layer is formed of a rubber sheet in which 16 parts by weight of aramid short fibers are added to 100 parts by weight of HNBR (rubber component), and the back rubber layer is formed of a rubber sheet of HNBR containing no short fibers. . Further, an aramid canvas subjected to RFL treatment was used as the tooth surface canvas, and a core made of glass fiber was used as the core. The thickness before molding of the rubber sheet for forming the tooth surface protective layer, the tooth rubber layer, and the back rubber layer was 0.3 mm, 1.3 mm, and 1.5 mm, respectively. In addition, as the rubber sheet of HNBR, a rubber sheet having the same composition as in Example 1 was used. The tooth profile of the belt was an RU tooth profile, and the belt width was 19 mm.

[Example 8]
Same as Example 7 except that the thickness of the rubber sheet for forming the tooth surface protective layer, tooth rubber layer and back rubber layer was 0.2 mm, 1.4 mm and 1.5 mm, respectively. Implemented.

[Example 9]
The same as in Example 7 except that the thickness before molding of the rubber sheet for forming the tooth surface protective layer, the tooth rubber layer, and the back rubber layer was 0.15 mm, 1.45 mm, and 1.5 mm, respectively. Implemented.

[Comparative Example 4]
The same as in Example 7 except that the thickness before forming the rubber sheet for forming the tooth rubber layer and the back rubber layer was 1.5 mm and 1.6 mm without providing the tooth surface protective layer. Implemented.

  In Examples 7 to 9 and Comparative Example 4, the evaluation by the servo pulser test was performed by the same method as described above, but a higher load was applied than the belts of Examples 1 to 7 and Comparative Examples 1 to 3. It was. Specifically, the upper limit value of the load was set to 650N and 600N, and the number of cycles until the tooth 46a was broken was measured. The results are shown in Table 3. Table 3 also shows the thickness D2 of the tooth surface protective layer of the belt after molding, the thickness D1 of the tooth portion, and the thickness ratio D2 / D1.

  As is clear from Table 3, when the thickness ratio (D2 / D1) is about 0.06 and 0.09, the durability performance is good under both high load (650 N) and medium load (600 N). In particular, it can be understood that particularly good results were obtained at a thickness ratio of 0.09. Further, when the thickness ratio is relatively large, 0.12, the durability performance was the same as that of the comparative example under a high load, but it can be understood that the durability performance was improved under a medium load.

  Next, in addition to Example 2 above, toothed belts of Example 10 and Comparative Examples 5 and 6 shown below were prepared, and the following running tests were conducted to confirm the oil resistance of these belts. did. The results are shown in Table 4.

[Example 10]
The toothed belt according to Example 10 corresponds to the first embodiment. The tooth surface protective layer was formed of a rubber sheet having a rubber component made of HNBR alone and containing no short fibers. The tooth rubber layer is formed of an HNBR rubber sheet in which 12 parts by weight of nylon short fibers are added to 100 parts by weight of HNBR (rubber component), and the back rubber layer is formed of an HNBR rubber sheet not including short fibers. Formed. Further, an aramid canvas subjected to RFL treatment was used as the tooth surface canvas, and a core made of glass fiber was used as the core. The thickness before molding of the rubber sheet for forming the tooth surface protective layer, the tooth rubber layer, and the back rubber layer was 0.2 mm, 1.2 mm, and 1.5 mm, respectively. The tooth profile of the belt was a YU tooth profile, and the belt width was 13 mm.

[Comparative Example 5]
In Comparative Example 5, the tooth surface protective layer was not provided, and the thickness of the rubber sheet for forming the tooth rubber layer and the back rubber layer before molding was 1.4 mm and 1.5 mm, respectively. Example 10 was carried out in the same manner as in Example 10.

[Comparative Example 6]
Comparative Example 6 was carried out in the same manner as Comparative Example 5 except that the tooth surface canvas was subjected to RFL treatment and then further subjected to HNBR rubber paste treatment on the tooth surface side.

[Running test]
In the running test, a belt was installed on the driving and driven pulleys in an atmosphere of 120 ° C., the belt was run with tension applied to the belt with a tensioner, and the number of repeated loads until the belt was broken was measured. The rotation speed during belt running was 6000 rpm. In this running test, oil droplets with an oil temperature of 140 ° C. were constantly applied to the running belt.

  As can be seen from Table 4, it can be understood that Examples 2 and 10 provided with the tooth surface protective layer had better oil resistance than the comparative example. In particular, in Example 2, since the back surface protective layer was provided in addition to the tooth surface protective layer, and these were formed of a mixture of HNBR and fluororubber, the oil resistance performance was further improved. On the other hand, in Comparative Example 6 in which the tooth surface protective layer was formed by the rubber paste treatment, the oil resistance performance could not be sufficiently improved because the thickness was small.

DESCRIPTION OF SYMBOLS 10 Toothed belt 12 Tooth rubber layer 12A Tooth part 14 Back rubber layer 18 Tooth surface canvas 20 Tooth surface protective layer 24 Short fiber (reinforcement material)
28 Back canvas 30 Back protective layer

Claims (10)

  A toothed belt comprising a tooth portion formed of an elastomer and a tooth surface canvas covering the surface of the tooth portion, further comprising a tooth surface protection layer formed of a rubber sheet provided outside the tooth surface canvas. A toothed belt characterized by that.   The toothed belt according to claim 1, wherein a ratio of the thickness of the tooth surface protective layer to the thickness of the tooth portion is 0.03 to 0.20.   The toothed belt according to claim 1, wherein the tooth surface protective layer contains at least one of fluororubber and HNBR.   The toothed belt according to claim 3, wherein the tooth surface protective layer contains fluororubber and HNBR.   The toothed belt according to claim 1, further comprising a reinforcing material for improving the hardness of the tooth portion.   The toothed belt according to claim 1, further comprising a back protective layer made of a rubber sheet provided on a back surface of the toothed belt.   The toothed belt according to claim 6, wherein a back canvas is laminated inside the back protective layer.   The toothed belt according to claim 1, wherein the tooth surface protective layer has a thickness of 0.1 to 0.5 mm.   The tooth surface canvas and the tooth surface protective layer are press-bonded to form a shape corresponding to the surface of the tooth part, and the vulcanization step after the preforming step is manufactured. The toothed belt according to claim 1. A first pre-forming step of obtaining a tooth surface molded body by crimping the tooth surface canvas and the tooth surface protective layer, and forming them into a corrugated shape;
A second pre-molding step of obtaining a tooth part molding by laminating a tooth rubber layer for forming the tooth part of the belt on the tooth surface canvas side of the tooth surface molding;
A first mounting step of mounting the tooth part molded body on a molding die such that the tooth surface protective layer is disposed inside;
A second mounting step of mounting a core wire and a back rubber layer on the outside of the tooth part molded body on the molding die;
And a vulcanization step of obtaining a belt slab by performing vulcanization molding after the second mounting step.

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