JP6435148B2 - Elastic crawler mold - Google Patents

Description

  The present invention relates to an elastic crawler mold.

  Crawler type traveling devices are used in agricultural machines such as combine harvesters and construction machines such as backhoes. This traveling device has an elastic crawler.

  FIG. 9 shows a traveling device 4 having an elastic crawler 2. The traveling device 4 includes a sprocket 6, an idler 8, a plurality of wheels 10, and an elastic crawler 2. The sprocket 6 has a disk shape and has a large number of teeth 12 on the periphery thereof.

  The crawler 2 has an endless belt shape. The crawler 2 is bridged between the sprocket 6 and the idler 8.

  The crawler 2 includes an endless belt 14, a large number of lugs 16, and a large number of guides 18. Each lug 16 protrudes outward from the endless belt 14. The lug 16 is made of a crosslinked rubber. Each guide 18 protrudes inward from the endless belt 14. The guide 18 includes a cushion 20 made of crosslinked rubber and a cored bar 22 covered with the cushion 20. The material of the cored bar 22 is steel. The cored bar 22 includes a plate-shaped main body 24 and a wedge 26 protruding from the main body 24. In FIG. 9, three lugs 16 are shown. The other lugs 16 are not shown. In FIG. 9, three guides 18 are shown. Illustration of the other guides 18 is omitted.

  The crawler 2 further has a number of holes 28. Each hole 28 is located between the cored bar 22 and the cored bar 22 adjacent thereto. The teeth 12 of the sprocket 6 can enter the holes 28.

  When the sprocket 6 rotates in the traveling device 4, the teeth 12 entering the hole 28 drive the crawler 2. By this driving, the traveling device 4 moves forward. The guide 18 is disposed so as to sandwich the sprocket 6. Thereby, the movement of the sprocket 6 is restrained. The guide 18 passes between the pair of wheels 10. These wheels 10 guide the crawler 2.

  A mold is used in the production of the crawler. In this production, a two-piece mold is usually used. The mold includes an upper mold and a lower mold.

  FIG. 10 shows a part of a lower mold 32 of a conventional mold 30. The lower mold 32 includes a recess 34.

  In manufacturing the crawler 2, the wedge 26 of the cored bar 22 is put into the recess 34. The rubber composition processed into a sheet shape is put into the mold 30 together with other necessary members. The mold 30 is closed, and the members put into the mold 30 are pressurized. The mold 30 is heated. The mold 30 is heated. The rubber composition flows by pressurization and heating. Thereby, the rubber composition is injected between the recess 34 and the wedge 26. The rubber composition causes a crosslinking reaction, and the crawler 2 shown in FIG. 9 is obtained.

  An example of a mold for manufacturing a crawler is described in JP-A-2006-117134.

JP 2006-117134 A

  As shown in FIG. 10, the wedge 26 has a tapered shape. The cored bar 22 is put into the mold 30 with the front end of the wedge 26 facing down. For this reason, as indicated by a two-dot chain line, the cored bar 22 tends to fall down obliquely. In the crawler 2 manufactured by the mold 30, the position accuracy of the cored bar 22 is insufficient. With this mold 30, it is difficult to manufacture the crawler 2 having high quality.

  A support member for supporting the cored bar may be provided in the mold. In this case, the crawler is manufactured by bringing the mandrel into contact with the support member. In this mold, it is not possible to coat rubber on the portion of the core metal of the crawler that is in contact with the support member. In this crawler, a part of the core metal is exposed. As described above, the material of the metal core is steel. Rust tends to occur on the exposed metal core. Rust promotes the peeling of the rubber from the mandrel. The crawler manufactured with this mold is inferior in durability.

  In the mold described in JP-A-2006-117134, the reinforcing core material corresponding to the cored bar is supported by positioning pins. Since the positioning pin has a small size, exposure of the reinforcing core material is suppressed. However, since the angle formed by the side surface of the positioning pin with respect to the cavity surface is not taken into consideration, the rubber covered with the core metal is easily damaged when the crawler is taken out of the mold. Since it is difficult for rubber to enter between the positioning pin and the reinforcing core material, the entire reinforcing core material cannot be covered with rubber. Since the exposure of the reinforcing core material cannot be prevented, in this mold, the reinforcing core material may be rusted. This mold has room for improvement from the viewpoint of producing a crawler with high quality and excellent durability.

  An object of the present invention is to provide a mold from which an elastic crawler having high quality and excellent durability can be obtained.

  The mold according to the present invention includes an endless belt and a large number of guides juxtaposed in the rotational direction and projecting from the endless belt, and these guides are spaced apart from each other in the width direction. Are arranged so as to be parallel to each other in the rotation direction, and each guide includes a pair of guide slopes extending from its apex to a hem and a pair of guide side surfaces spanned between the two guide slopes. The guide portion includes a cushion formed of a rubber composition and a cored bar located inside the cushion, and the cored bar includes a plate-shaped main body and a wedge protruding from the main body. Each wedge has a pair of wedge slopes and a pair of wedge sides, each wedge slope being located inside each of the guide slopes, Wedge side is located inside the respective said guide sides, it is used for manufacturing the elastic crawler. The mold is provided with a recess into which the wedge is introduced and the rubber composition is injected between the mold and the wedge. The depression includes a slope forming surface that forms the guide slope and a side surface that forms the guide side surface. The slope forming surface includes a reference surface and a protrusion protruding from the reference surface toward the inside of the recess. The protrusion includes a protrusion slope extending from the apex toward the reference surface. The protruding slope is inclined with respect to the reference plane, and the inclination angle is an obtuse angle. When the wedge is thrown into the recess, the protrusion comes into contact with the wedge slope at its apex.

  Preferably, in the mold for the elastic crawler, the wedge of the crawler has a maximum width, and when the wedge is inserted into the recess, the wedge corresponds to a position where the wedge shows the maximum width. When the specific position is set as the first reference position, the first reference position is upstream of the rubber composition injection from the top of the protrusion. In the thickness direction of the mold, the ratio of the length from the top of the protrusion to the first reference position to the length from the bottom of the recess to the first reference position is 0.2 or less.

  Preferably, in the elastic crawler mold, in the thickness direction of the mold, the ratio of the length of the protrusion to the length from the bottom of the recess to the first reference position is 0.3 or more and 0.5 or less. It is.

  Preferably, in this elastic crawler mold, when the specific position of the recess is the second reference position, the protrusion has the maximum length in the width direction of the mold. The ratio of the maximum length of the protrusion to the length of the recess is 0.1 or more and 0.4 or less.

  Preferably, in the elastic crawler mold, in the pair of recesses arranged apart from each other in the width direction of the mold, the protrusion is formed on each of the one slope forming surface and the other slope forming surface of the one recess. The protrusions are provided on each of the one slope forming surface of one recess and the other slope forming surface of the other recess.

  Preferably, in the mold for the elastic crawler, in the length direction of the mold, the length from the top of one of the protrusions to the top of the other protrusion, and the position of the top of the wedge to be introduced into the recess The difference with the width corresponding to is 0.5 mm or more and 2.0 mm or less.

  The elastic crawler according to the present invention is obtained using any one of the molds described above.

  In the mold for an elastic crawler according to the present invention, the protrusion supports the wedge of the metal core at the apex. With this mold, the mandrel is difficult to collapse. In the crawler manufactured by this mold, the position accuracy of the cored bar is high. This mold contributes to the production of high quality crawlers. In addition, in this mold, the protrusion slope of the protrusion is inclined with respect to the reference plane, and the inclination angle is an obtuse angle. For this reason, when taking out the crawler from the mold, the cushion is hardly damaged. Since the rubber composition also enters between the protrusion and the wedge, the core metal is entirely covered with the rubber composition. Since the core metal is prevented from being exposed, the core metal is less likely to rust with this crawler. The crawler manufactured with this mold is excellent in durability. According to the mold of the present invention, an elastic crawler having high quality and excellent durability can be obtained.

FIG. 1 is a front view showing a part of an elastic crawler according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view illustrating a state of manufacturing the elastic crawler illustrated in FIG. 1. FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is an enlarged cross-sectional view illustrating a part of the mold of FIG. FIG. 7 is an enlarged cross-sectional view showing another variation of the protrusion of FIG. FIG. 8 is an enlarged cross-sectional view showing still another variation of the protrusion of FIG. FIG. 9 is a front view illustrating a traveling device having a conventional elastic crawler. FIG. 10 is a cross-sectional view showing a part of a conventional mold. FIG. 11 is a cross-sectional view showing a protrusion of the mold of Comparative Example 2.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  1 and 2, an elastic crawler 36 is shown. FIG. 2 also shows the ground G and the wheel 10. In FIG. 1, the left-right direction (namely, X direction) is a width direction, and the up-down direction (namely, Y direction) is a rotation direction. In FIG. 2, the upward direction is the inner direction of the loop formed by the crawler 36. In FIG. 2, the downward direction is the outward direction of the loop formed by the crawler 36.

  The crawler 36 includes an endless belt 38, a large number of lugs 40, and a large number of guides 42. The endless belt 38 extends in the rotational direction. The endless belt 38 is not provided with an end. The endless belt 38 forms a loop.

  A large number of lugs 40 are arranged along the rotation direction. In other words, the multiple lugs 40 are arranged in parallel in the rotational direction. Each lug 40 extends in the width direction. The lug 40 is separated from the adjacent lug 40. The lug 40 protrudes outward from the endless belt 38. The lug 40 contributes to traction.

  A large number of guides 42 are arranged along the rotation direction. In other words, the many guides 42 are arranged in parallel in the rotation direction. As shown in FIG. 2, in the width direction, two guides 42 are arranged with a gap therebetween. Although not shown, in this crawler 36, a pair of guides 42 arranged in parallel in the width direction are arranged along the rotation direction. In other words, in this crawler 36, a large number of guides 42 are arranged such that a pair of guides 42 arranged in parallel in the width direction are arranged in parallel in the rotation direction. Each guide 42 is separated from the adjacent guide 42. The guide 42 protrudes inward from the endless belt 38. The guide 42 has an inwardly tapered shape in a cross section perpendicular to the length direction, that is, in the cross section shown in FIG. The guide 42 includes a pair of guide side surfaces 46 that extend from the apex 44 so as to extend toward the bottom.

  FIG. 3 shows a cross section of the guide 42. In FIG. 3, the left-right direction is the rotational direction, and the direction perpendicular to the paper surface is the width direction. The cross section shown in FIG. 3 is a cross section of the crawler 36 perpendicular to the width direction. In FIG. 3, the upward direction is the inner direction of the loop formed by the crawler 36. The downward direction is the outward direction of the loop formed by the crawler 36.

  As shown in FIG. 3, the guide 42 has an inwardly tapered shape. The guide 42 includes a pair of guide slopes 48 that extend from the apex 44 so as to extend toward the bottom. As described above, the guide side surface 46 is bridged between the two guide slopes 48.

  As illustrated in FIG. 1C, the crawler 36 includes an elastic body 50, a pair of tensile bodies 52, and a number of core bars 54. The members constituting the crawler 36 are not limited to the elastic body 50, the pair of tensile bodies 52, and the many core bars 54. The crawler 36 can include other members other than the elastic body 50, the pair of tensile bodies 52, and the multiple core bars 54 as necessary.

  The elastic body 50 is formed by crosslinking a rubber composition. In other words, the elastic body 50 is made of a crosslinked rubber. The rubber composition contains a base rubber. Examples of the base rubber include natural rubber, polyisoprene, polybutadiene, and styrene-butadiene copolymer. A reinforcing agent, a crosslinking agent, a softening agent, stearic acid, zinc oxide, an anti-aging agent, a wax, a crosslinking aid and the like are added to the rubber composition as necessary.

  As shown in FIG. 2, each tensile body 52 is embedded in the elastic body 50. The tensile body 52 is located outside the cored bar 54. The tensile body 52 includes a plurality of cords arranged in parallel. Each cord extends substantially along the direction of rotation. Preferably, the cord is made of a metal material. Examples of preferable materials for the cord include ordinary steel and alloy steel. An organic fiber may be used for the cord. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The tensile body 52 may be configured by a cord wound in a spiral shape.

  As shown in FIG. 1, a large number of core bars 54 are arranged along the rotation direction. Each cored bar 54 extends in the width direction. The cored bar 54 is separated from the adjacent cored bar 54. As shown in FIG. 2, the cored bar 54 is embedded in the elastic body 50. The core metal 54 is made of a metal material. Examples of the material of the core metal 54 include ordinary steel and alloy steel.

  The cored bar 54 includes a main body 56 and a pair of wedges 58. The main body 56 has a plate shape. Each wedge 58 protrudes inward from the main body 56. One wedge 58 and the other wedge 58 are arranged at an interval in the width direction. The wedge 58 includes a pair of wedge side surfaces 60. As shown in FIG. 2, each wedge side surface 60 extends from the apex 62 of the wedge 58 in a flared manner. The wedge 58 further includes a pair of wedge slopes 64. As shown in FIG. 3, at the front end portion of the wedge 58, each wedge slope 64 extends from the apex 62 of the wedge 58 in a flared manner. Between the front end portion of the wedge 58 and the main body 56, that is, the root portion of the wedge 58 is constricted. This constriction contributes to weight reduction of the crawler 36.

  In FIG. 3, the symbol PW represents the position where the wedge 58 shows the maximum width. The wedge 58 has a maximum width. In this crawler 36, the width of the wedge 58 is obtained based on the length from the wedge slope 64 located on the front side to the wedge slope 64 located on the rear side in the rotation direction.

  In the crawler 36, the endless belt 38 includes an elastic body 50, a main body 56 of a core metal 54, and a pair of tensile bodies 52. In the endless belt 38, the main body 56 and the pair of tensile bodies 52 are embedded in the elastic body 50.

  In this crawler 36, the lug 40 is constituted by an elastic body 50. In this crawler 36, the rubber composition for the elastic body 50 constituting the lug 40 is equivalent to the rubber composition for the elastic body 50 of the endless belt 38. The elastic body 50 of the lug 40 may be made of a rubber composition different from the rubber composition for the elastic body 50 of the endless belt 38.

  In the crawler 36, the guide 42 includes an elastic body 50 and a wedge 58 of the core metal 54. As apparent from FIG. 3, the wedge 58 is embedded in the elastic body 50. In the crawler 36, the guide 42 includes an elastic body 50 and a cored bar 54 positioned inside the elastic body 50. In the present invention, the elastic body 50 in the portion of the guide 42 is also referred to as a cushion 66. The cushion 66 prevents the core metal 54 from coming into direct contact with the wheel 10, the sprocket 6 and the like. As a result, noise and vibration during travel are reduced. In the crawler 36, the rubber composition for the elastic body 50 constituting the cushion 66 is equivalent to the rubber composition for the elastic body 50 of the endless belt 38. The elastic body 50 of the cushion 66 may be made of a rubber composition different from the rubber composition for the elastic body 50 of the endless belt 38.

  As apparent from FIGS. 2 and 3, the wedge 58 is covered with a cushion 66. In this guide 42, each wedge slope 64 is located inside each guide slope 48. Each wedge side surface 60 is located inside each guide side surface 46.

  In the production of the crawler 36 described above, a mold is used.

  FIG. 4 shows a part of the mold 68. In FIG. 4, the left-right direction is the length direction of the mold 68, and the direction perpendicular to the paper surface is the width direction of the mold 68. The length direction of the mold 68 corresponds to the rotation direction of the crawler 36. The width direction of the mold 68 corresponds to the width direction of the crawler 36. In FIG. 4, the vertical direction is the thickness direction of the mold 68. This thickness direction coincides with the direction of the vertical line. In FIG. 4, the upward direction corresponds to the outward direction of the loop formed by the crawler 36. The downward direction corresponds to the inner direction of the loop formed by the crawler 36.

  The mold 68 includes a lower mold 70. Although not shown, the mold 68 also includes an upper mold. This mold 68 is a two-piece mold. In this mold 68, the upper die and the lower die 70 are combined to form a cavity surface 72 that forms the outer surface of the crawler 36.

  The lower mold 70 includes a horizontal plane 74. The horizontal plane 74 is a part of the cavity surface 72. The horizontal surface 74 forms the outer surface of the endless belt 38.

  The lower mold 70 further includes a recess 76. The recess 76 is a part of the cavity surface 72. The recess 76 forms the outer surface of the guide 42. As described above, the crawler 36 is provided with a number of guides 42. Therefore, the lower mold 70 includes a large number of depressions 76. As shown in FIG. 4, in manufacturing the crawler 36 by the mold 68, the wedge 58 of the cored bar 54 is put into the recess 76.

  In the mold 68, the recess 76 includes a slope forming surface 78 that forms the guide slope 48 and a side surface forming surface 80 that forms the guide side surface 46. As described above, the guide 42 includes a pair of guide slopes 48 and a pair of guide side surfaces 46. Accordingly, the recess 76 includes a pair of slope forming surfaces 78 and a pair of side surface forming surfaces 80.

  In this mold 68, the slope forming surface 78 includes a reference surface 82 and a protrusion 84. The protrusion 84 protrudes from the reference surface 82 toward the inside of the recess 76. The protrusion 84 includes a protrusion slope 88 that extends from the apex 86 toward the reference surface 82. The protrusion slope 88 extends substantially radially from the apex 86 of the protrusion 84.

  FIG. 5 is a cross-sectional view taken along line VV in FIG. In FIG. 5, the left-right direction is the width direction of the mold 68, and the direction perpendicular to the paper surface is the length direction of the mold 68. In FIG. 5, the vertical direction is the thickness direction of the mold 68. In FIG. 5, the upward direction corresponds to the outward direction of the loop formed by the crawler 36. The downward direction corresponds to the inner direction of the loop formed by the crawler 36. In FIG. 5, a wedge 58 of the cored bar 54 is indicated by a two-dot chain line.

  In this mold 68, the outline of the boundary between the protrusion 84 and the reference surface 82 is substantially rectangular. As shown in FIG. 5, each side constituting the contour extends in the thickness direction or the width direction of the mold 68. The contour may be configured such that each side extends while being inclined with respect to the thickness direction or the width direction. This outline may be a circle or an ellipse. The boundary contour is appropriately determined as necessary.

  As shown in FIG. 5, the protrusion 84 is provided so as to be positioned between one wedge side surface 60 and the other wedge side surface 60 in a state where the wedge 58 is inserted into the recess 76. In this state, the protrusion 84 faces the wedge slope 64.

  Using the mold 68 described above, the crawler 36 is manufactured as follows.

  In the production of the crawler 36, a rubber composition processed into a sheet shape, a tensile body 52, and a cored bar 54 are prepared. The mold 68 is set in a vulcanizer (not shown). The mold 68 is heated. The temperature of the mold 68 is maintained at a temperature for manufacturing the crawler 36.

  The mold 68 is opened. The wedge 58 of the cored bar 54 is put into the recess 76 of the lower mold 70. As shown in FIG. 4, the cored bar 54 is put into the recess 76 with the apex 62 of the wedge 58 facing down.

  The lower mold 70 is charged with a rubber composition. The rubber composition is set on the horizontal surface 74 of the lower mold 70. A tensile body 52 is further introduced into the lower mold 70. The tensile body 52 is set outside the core metal 54 and the rubber composition. The lower mold 70 is further charged with a rubber composition. This rubber composition is set outside the tensile body 52. This completes the assembly of the raw cover (also referred to as an uncrosslinked crawler).

  In this production, when the setting of the rubber composition, the cored bar 54 and the tensile body 52 is completed, the mold 68 is closed. Thereby, the lower mold 70 and the upper mold are combined. Within the cavity, the raw cover is pressurized. Since the mold 68 is heated, the raw cover is heated. The rubber composition flows in the cavity by pressurization and heating. Thereby, the rubber composition is injected between the recess 76 and the wedge 58. The rubber composition causes a crosslinking reaction by heating. Thereby, the crawler 36 shown by FIGS. 1-3 is obtained.

  In this production, the rubber composition set on the horizontal surface 74 of the lower mold 70 is injected toward the bottom 90 of the recess 76. Therefore, in this recess 76, the horizontal plane 74 side is the upstream side of this injection.

  In this production, when the wedge 58 is inserted into the recess 76, the protrusion 84 comes into contact with the wedge slope 64 of the cored bar 54 at its apex. In other words, the protrusion 84 supports the wedge 58 of the cored bar 54 at its apex 86. In the mold 68, the cored bar 54 is difficult to fall down. In the crawler 36 manufactured by the mold 68, the position accuracy of the cored bar 54 is high. This mold 68 contributes to the production of a high-quality crawler 36.

  As described above, the cored bar 54 includes a pair of wedges 58, and one wedge 58 and the other wedge 58 are arranged with an interval in the width direction. For this reason, also in this mold 68, a pair of hollow 76 is arrange | positioned at intervals in the width direction so as to correspond to a pair of wedge 58 of the metal core 54. In the present application, of the pair of depressions 76, one depression 76 is referred to as a first depression 76 and the other depression 76 is referred to as a second depression 76.

  In the mold 68, for each of the first recess 76 and the second recess 76, a protrusion 84 is provided on each of the slope forming surface 78a and the other slope forming surface 78b. The arrangement of the protrusions 84 contributes to stable holding of the cored bar 54. In the mold 68, the cored bar 54 is difficult to fall down. The crawler 36 manufactured with this mold 68 is of high quality. Since the cored bar 54 put into the recess 76 only needs to be stably held, one of the first recess 76 and the second recess 76 is formed with one inclined surface 78a and the other inclined surface. A protrusion 84 may be provided on each of the surfaces 78b. A protrusion 84 may be provided on each of the one slope forming surface 78a of the first recess 76 and the other slope forming surface 78b of the second recess 76, or the other slope forming surface 78b and the first slope forming surface 78b of the first recess 76 may be provided. A protrusion 84 may be provided on each of the one slope forming surface 78 a of the two recesses 76. Thereby, the number of the protrusions 84 used for supporting the cored bar 54 can be reduced. The reduction in the number of protrusions 84 contributes to the production cost.

  FIG. 6 shows a part of the recess 76 of FIG. FIG. 6 shows a portion of the protrusion 84 of the recess 76. In the mold 68, the projecting slope 88 is inclined with respect to the reference surface 82.

  In FIG. 6, the angle α represents an inclination angle formed by the protrusion inclined surface 88 with respect to the reference surface 82. The inclination angle α is obtained based on the tangent line of the reference surface 82 and the tangent line of the protrusion slope 88 at the boundary between the protrusion 84 and the reference surface 82. When the boundary between the reference surface 82 and the projection slope 88 is expressed by an arc, the inclination angle α is based on the tangent of the reference plane 82 at one end of the arc and the tangent of the projection slope 88 at the other end. can get.

  In the present application, the inclination angle α on the upstream side of the injection of the rubber composition is referred to as a first inclination angle α1. The inclination angle α on the downstream side of this injection is referred to as a second inclination angle α2. When the inclination angle α measured along the boundary between the protrusion 84 and the reference surface 82 is not uniform, the inclination angle α is an average value of the first inclination angle α1 and the second inclination angle α2. Is done.

  In this mold 68, the inclination angle α is an obtuse angle. For this reason, when the crawler 36 is taken out from the mold 68, the cushion 66 is hardly damaged. Since the rubber composition also enters between the protrusion 84 and the wedge 58, the core metal 54 is entirely covered with the rubber composition. Since the exposure of the cored bar 54 is prevented, the cored bar 54 is not easily rusted by the crawler 36. The crawler 36 manufactured with this mold 68 is excellent in durability. As described above, in the crawler 36 manufactured by the mold 68, the position accuracy of the cored bar 54 is high. This mold 68 contributes to the production of a high-quality crawler 36. According to the mold 68 of the present invention, the elastic crawler 36 having high quality and excellent durability can be obtained. In this respect, the inclination angle α is preferably 100 ° or more and more preferably 170 ° or less. Accordingly, the upstream side inclination angle α1 is preferably 100 ° or more, and more preferably 170 ° or less. The inclination angle α2 on the downstream side is preferably 100 ° or more, and more preferably 170 ° or less.

  In this fabrication, the rubber composition is poured toward the bottom 90 of the recess 76. At this time, the rubber composition flows so as to go around the protrusion 84 from the upstream side of injection. From the standpoint that the flow hindrance by the protrusions 84 is suppressed and the core metal 54 is prevented from being exposed, the first inclination angle α1 on the upstream side of the injection of the rubber composition is the second inclination angle α2 on the downstream side of the injection. It is preferable that the inclination angle α is configured to be larger than that. From this viewpoint, the difference (α1−α2) between the first inclination angle α1 and the second inclination angle α2 is preferably 10 ° or more, and more preferably 30 ° or less. When providing a difference between the first inclination angle α1 and the second inclination angle α2, it is more preferable that the inclination angle α is gradually decreased from the upstream side toward the downstream side.

  In this mold 68, as shown in FIG. 6, the projecting slope 88 is represented by a straight line extending from the apex 86 toward the reference surface 82. The protruding slope 88 may be represented by an arc as shown in FIG. In this mold 68, as shown in FIG. 6, the boundary between the projecting slope 88 and the reference surface 82 is represented by an arc. As shown in FIG. 8, this boundary may be represented by the intersection of the projecting slope 88 and the reference surface 82 without providing an arc. The contour of the projecting slope 88 is appropriately determined in consideration of the flow of the rubber composition.

  In FIG. 4, a solid line L1 represents a specific position of the recess 76 corresponding to the position PW where the wedge 58 exhibits the maximum width. This position L1 is referred to as a first reference position.

  As shown in FIG. 4, the first reference position L <b> 1 is on the upstream side of the injection of the rubber composition with respect to the vertex 86 of the protrusion 84. In the mold 68, the protrusion 84 effectively contributes to the support of the wedge 58 introduced into the recess 76. In the mold 68, the cored bar 54 is difficult to fall down. The crawler 36 manufactured with this mold 68 is of high quality.

  In FIG. 4, a double-headed arrow H is the length from the bottom 90 of the recess 76 to the first reference position L1. A double arrow a is a length from the apex 86 of the protrusion 84 to the first reference position L1. The length H and the length a are measured along the thickness direction of the mold 68.

  In the mold 68, the ratio of the length a to the length H is preferably 0.2 or less. By setting this ratio to 0.2 or less, the apex 86 of the protrusion 84 is disposed at an appropriate position with respect to the position PW where the wedge 58 exhibits the maximum width. In the mold 68, the protrusion 84 effectively contributes to the support of the wedge 58 introduced into the recess 76. In the mold 68, the cored bar 54 is difficult to fall down. The crawler 36 manufactured with this mold 68 is of high quality.

  In FIG. 4, a double-headed arrow b represents the length from the upstream end of the protrusion 84 to the downstream end thereof. This length b is measured along the thickness direction of the mold 68. This length b is represented by the maximum length among the lengths measured at the protrusions 84.

  In the mold 68, the ratio of the length b to the length H is preferably 0.3 or more and 0.5 or less. By setting this ratio to be 0.3 or more, when the crawler 36 is taken out from the mold 68, the projection 84 is smoothly pulled out from the cushion 66. This prevents the rubber covered with the cored bar 54 from being damaged. The crawler 36 manufactured with the mold 68 is of high quality. By setting this ratio to 0.5 or less, inhibition of the flow of the rubber composition by the protrusions 84 is suppressed, and exposure of the cored bar 54 is prevented. In this crawler 36, the cored bar 54 is not easily rusted. The crawler 36 manufactured with this mold 68 is excellent in durability.

  In FIG. 4, a double-headed arrow e represents the length from the vertex 86 of one projection 84 to the vertex 86 of the other projection 84. Reference numeral Pt represents a specific position of the wedge slope 64 facing the apex 86 of the protrusion 84 in a state where the wedge 58 is inserted into the recess 76. A double arrow f represents the length from one position Pt to the other position Pt. The length f is the width of the wedge 58 corresponding to the position of the vertex 86 of the protrusion 84. The length e and the length f are measured along the length direction of the mold 68.

  In this mold 68, the difference (ef) between the length e and the length f is preferably 0.5 mm or more and 2.0 mm or less. By setting the difference (ef) to be 0.5 mm or more, inhibition of the flow of the rubber composition by the protrusions 84 can be suppressed. Since the rubber composition also enters between the protrusion 84 and the wedge 58, the core metal 54 is entirely covered with the rubber composition. Since the exposure of the cored bar 54 is prevented, the cored bar 54 is not easily rusted by the crawler 36. The crawler 36 manufactured with this mold 68 is excellent in durability. By setting this difference to be equal to or less than 2.0 mm, the protrusion 84 effectively contributes to the support of the wedge 58 introduced into the recess 76. In the mold 68, the cored bar 54 is difficult to fall down. The crawler 36 manufactured with this mold 68 is of high quality.

  In FIG. 5, reference sign g <b> 1 represents an intersection of an extension line of one side surface forming surface 80 a and an extension line of the bottom 90. This intersection point g1 is a boundary between one side surface forming surface 80a and the bottom 90. The symbol g2 represents the intersection of the extension line of the other side surface forming surface 80b and the extension line of the bottom 90. This intersection point g2 is a boundary between the other side surface forming surface 80b and the bottom 90.

  In the mold 68, in the width direction, the protrusion 84 is located between the boundary g1 and the boundary g2. In this mold 68, the protrusion 84 contacts the wedge slope 64. The arrangement of the protrusions 84 contributes to stable holding of the cored bar 54. In the mold 68, the cored bar 54 is difficult to fall down. The crawler 36 manufactured with this mold 68 is of high quality.

  In FIG. 5, a solid line L <b> 2 represents a position where the protrusion 84 has the maximum length in the width direction of the mold 68. This position L2 is referred to as a second reference position. A double-headed arrow c represents the maximum length of the protrusion 84 in the width direction of the mold 68. A double-headed arrow d indicates the length of the recess 76 at the second reference position L2. The length d is represented by the length from one side surface forming surface 80 to the other side surface forming surface 80 at the second reference position L2.

  In the mold 68, the ratio of the length c to the length d is preferably 0.1 or more and 0.4 or less. When this ratio is set to 0.1 or more, when the crawler 36 is taken out from the mold 68, the projection 84 is smoothly pulled out from the cushion 66. In this mold 68, the cushion 66 is not easily damaged. The crawler 36 manufactured with the mold 68 is of high quality. By setting this ratio to 0.4 or less, inhibition of the flow of the rubber composition by the protrusions 84 is suppressed, and exposure of the cored bar 54 is prevented. In this crawler 36, the cored bar 54 is not easily rusted. The crawler 36 manufactured with this mold 68 is excellent in durability.

  In the mold 68, the protrusion 84 can be detachable. Thereby, even if the projection 84 is worn away by contact with the core metal 54, the support of the core metal 54 by the projection 84 is stably maintained by exchanging the portion of the projection 84. This configuration contributes to production costs because there is no need to renew the entire mold 68.

  In the mold 68, the surface of the protrusion 84 may be plated. The plating contributes to suppression of wear of the protrusions 84. Since plating suppresses the friction of rubber against the protrusions 84, when the crawler 36 is taken out from the mold 68, the protrusions 84 are smoothly pulled out from the cushion 66. In this mold 68, damage to the cushion 66 is effectively prevented. The crawler 36 manufactured with the mold 68 is of high quality.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A mold having the basic configuration shown in FIGS. 4-6 and having the specifications shown in Table 1 below was prepared. A crawler was produced using this mold. The first inclination angle α1 was 162 °. The second inclination angle α2 was 146 °. Therefore, the inclination angle α was 154 °.

[Example 2]
A mold of Example 2 was prepared in the same manner as Example 1 except that the shape of the protrusion was changed to the shape shown in FIG. A crawler was produced using this mold. The first inclination angle α1 was 144 °. The second inclination angle α2 was 132 °. Therefore, the inclination angle α was 138 °.

[Example 3]
A mold of Example 3 was prepared in the same manner as Example 1 except that the shape of the protrusion was changed to the shape shown in FIG. A crawler was produced using this mold. The first inclination angle α1 was 161 °. The second inclination angle α2 was 143 °. Therefore, the inclination angle α was 161 °.

[Comparative Example 1]
A mold of Comparative Example 1 was prepared in the same manner as Example 1 except that no protrusion was provided. A crawler was produced using this mold.

[Example 4-8]
A mold of Example 4-8 was prepared in the same manner as Example 1 except that the first inclination angle α1 and the second inclination angle α2 were adjusted so that the inclination angle α was as shown in Table 2 below. A crawler was manufactured using these molds. In the mold of Example 4-8, the inclination angle α measured along the boundary between the protrusion and the reference surface was uniform. Therefore, the inclination angle α1 and the inclination angle α2 are equivalent.

[Comparative Example 2]
A mold of Comparative Example 2 was prepared in the same manner as in Example 1 except that the shape of the protrusion was changed to the shape shown in FIG. A crawler was produced using this mold. The first inclination angle α1 was 90 °. The second inclination angle α2 was 90 °. Therefore, the inclination angle α was 90 °.

[Example 9-10]
Molds of Examples 9-10 were prepared in the same manner as in Example 1 except that the ratio (a / H) was as shown in Table 3 below. A crawler was manufactured using these molds.

[Examples 11-14]
Molds of Examples 11-14 were prepared in the same manner as in Example 1 except that the difference (ef) was as shown in Table 4 below. A crawler was manufactured using these molds.

[Example 15]
A mold of Example 15 was prepared in the same manner as Example 1 except that the first inclination angle α1 and the second inclination angle α2 were adjusted so that the inclination angle α was as shown in Table 4 below. A crawler was produced using this mold.

[Presence / absence of exposure]
The appearance of the manufactured crawlers (10) was visually observed. The degree of exposure of the core metal was rated according to the following criteria.
B: No exposure is observed in all of the crawlers produced. G: Partial exposure is observed. NG: All exposures are observed. The results are shown in Tables 1-4 below.

[Presence or absence of bias]
The position of the core metal in the produced crawlers (10) was confirmed. The thickness of the cushion covering the wedge side was measured. Based on this thickness, the degree of bias of the cored bar was rated according to the following criteria.
B: Unevenness is not recognized in all of the manufactured crawlers G: Unevenness is partially recognized NG: Unevenness is recognized in all, the results are shown in Tables 1-4 below.

  As shown in Table 1-4, the mold of the example has a higher evaluation than the mold of the comparative example. From this evaluation result, the superiority of the present invention is clear. In Example 1, a cushion having a thickness about 100 μm larger than that in Examples 6 and 15 was formed. From this, it was confirmed that increasing the upstream inclination angle α1 larger than the downstream inclination angle α2 contributes to the fluidity of the rubber composition.

  The mold described above can also be applied to the production of various types of crawlers.

2, 36 ... Crawler 4 ... Traveling device 6 ... Sprocket 10 ... Rolling wheel 12 ... Teeth 14, 38 ... Endless belt 16, 40 ... Lugs 18, 42 ... Guide 20, 66 ... Cushion 22, 54 ... Core metal 24, 56 ... Main body 26, 58 ... Wedge 30, 68 ... Mold 34, 76, 92 ... Recess 44 ... Vertex 48 of guide 42 ... Guide slope 54 ... Core metal 56 ... Body 58 ... Wedge 62 ... Apex of wedge 58 64 ... Wedge slope 72 ... Cavity surface 74 ... Horizontal planes 78, 78a, 78b ... slope forming surfaces 82, 96 ... reference planes 84, 98 ... projections 86 ... apexes of projections 84, 100 ... projection slopes

Claims (5)

An endless belt and a large number of guides juxtaposed in the rotational direction and projecting from the endless belt, and these guides are arranged so that a pair of guides spaced apart in the width direction are juxtaposed in the rotational direction. Each guide has a pair of guide slopes extending from its apex to the hem and a pair of guide side surfaces spanned between the two guide slopes. A cushion formed from a rubber composition and a cored bar located inside the cushion, the cored bar includes a plate-like body and a wedge protruding from the body, and the wedge is a pair of A wedge slope and a pair of wedge sides, each wedge slope is located inside each of the guide slopes, and each wedge side is Located inside the serial guide side, the elastic crawler, a method of producing using a mold,
The mold is provided with a recess into which the wedge is introduced and the rubber composition is injected between the mold and the wedge,
The depression has a slope forming surface forming the guide slope and a side forming surface forming the guide side surface;
The slope forming surface includes a reference surface and a protrusion protruding from the reference surface toward the inside of the recess,
The protrusion has a protrusion slope extending from the apex toward the reference plane,
The protruding slope is inclined with respect to the reference plane, and the angle of the inclination is an obtuse angle,
In a pair of recesses that are spaced apart in the width direction of the mold,
The protrusion is provided on each of the one slope forming surface and the other slope forming surface of one recess, or one of the slope forming surface of one recess and the other slope forming surface of the other recess. Each is provided with the above protrusions,
In the length direction of the mold, the length from the top of one of the protrusions to the top of the other protrusion is made larger than the width corresponding to the position of the top of the wedge introduced into the recess. The method of manufacturing an elastic crawler , wherein , when the wedge is inserted into the recess, the protrusion supports the wedge slope so that the wedge does not fall at the apex. When the wedge has the maximum width, and when the wedge is inserted into the depression, the specific position of the depression corresponding to the position where the wedge shows the maximum width is set as the first reference position. ,
The first reference position is upstream of the rubber composition injection from the top of the protrusion,
The ratio of the length from the top of the protrusion to the first reference position to the length from the bottom of the recess to the first reference position in the thickness direction of the mold is 0.2 or less. Item 2. A method for producing an elastic crawler according to Item 1. When the wedge has the maximum width, and when the wedge is inserted into the depression, the specific position of the depression corresponding to the position where the wedge shows the maximum width is set as the first reference position. ,
The ratio of the length of the protrusion to the length from the bottom of the recess to the first reference position in the thickness direction of the mold is 0.3 or more and 0.5 or less. Method for producing an elastic crawler. In the width direction of the mold, when the protrusion has a maximum length, and the specific position of the recess is the second reference position,
The method of manufacturing an elastic crawler according to any one of claims 1 to 3, wherein a ratio of a maximum length of the protrusion to a length of the recess at the second reference position is 0.1 or more and 0.4 or less. . In the length direction of this mold,
The difference between the length from the top of one of the protrusions to the top of the other protrusion and the width of the wedge that is put into the depression corresponding to the position of the top is 0.5 mm or more and 2.0 mm or less. The manufacturing method of the elastic crawler in any one of Claim 1 to 4.

Images