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EP-3868549-B2 - TREAD RUBBER FORMING METHOD AND TREAD RUBBER FORMING DEVICE

EP3868549B2EP 3868549 B2EP3868549 B2EP 3868549B2EP-3868549-B2

Inventors

  • ONIMATSU, HIROYUKI

Dates

Publication Date
20260513
Application Date
20210210

Claims (12)

  1. A tread rubber forming method (S2) for spirally winding and superposing tape-shaped unvulcanized rubber strips (GS1, GS2, GS3, and GS4) on an outer side in a radial direction of a cylindrical body (101) to form an annular tread rubber (10), the method (S2) comprising: a first step (S21) of winding and superposing a first rubber strip (GS1) while moving the first rubber strip (GS1) in an axial direction of the cylindrical body (101), to form a base layer (1); a second step (S22) of winding and superposing a non-electrically-conductive second rubber strip (GS2) in a region on one side in the axial direction on an outer circumferential surface of the base layer (1) while moving the second rubber strip (GS2) in the axial direction, to form a first intermediate layer (21), wherein the second step (S22) includes winding the second rubber strip (GS2) at a winding pitch that is larger than a width of the second rubber strip (GS2), to form a separation portion (23) separating adjacent portions of the second rubber strip (GS2) in the axial direction; a third step (S23) of winding and superposing a non-electrically-conductive third rubber strip (GS3) on an outer circumferential surface of the first intermediate layer (21) while moving the third rubber strip (GS3) in the axial direction, to form a first cap layer (31); a fourth step (S24) of winding, in a region on another side in the axial direction relative to the first intermediate layer (21) and the first cap layer (31), an electrically-conductive fourth rubber strip (GS4) from a position of contact with the base layer (1) to an outer circumferential surface of the first cap layer (31), to form an electrically-conductive layer (4), wherein the fourth step (S24) includes winding the fourth rubber strip (GS4) in a region that includes the separation portion (23); and a fifth step (S25) of winding and superposing, on an outer side in the radial direction of the base layer (1), the third rubber strip (GS3) in a region on the other side in the axial direction relative to the electrically-conductive layer (4) while moving the third rubber strip (GS3) in the axial direction, such that a portion of the electrically-conductive layer (4) is exposed to an outer side in the radial direction of the tread rubber (10), to form a second cap layer (32).
  2. The tread rubber forming method (S2) according to claim 1, wherein the fifth step (S25) includes winding the third rubber strip (GS3) in a region that includes the separation portion (23).
  3. A tread rubber forming method (S3) for spirally winding and superposing tape-shaped unvulcanized rubber strips (GS1, GS2, GS3, and GS4) on an outer side in a radial direction of a cylindrical body (101) to form an annular tread rubber (10), the method (S3) comprising: a first step (S31) of winding and superposing a first rubber strip (GS1) while moving the first rubber strip (GS1) in an axial direction of the cylindrical body (101), to form a base layer (1); a second step (S32) of winding and superposing a non-electrically-conductive second rubber strip (GS2) in a region on one side in the axial direction on an outer circumferential surface of the base layer (1) while moving the second rubber strip (GS2) in the axial direction, to form a first intermediate layer (21), wherein the second step (S32) includes winding and superposing the second rubber strip (GS2) such that an edge (21e), on the other side in the axial direction, of the first intermediate layer (21) is located on the other side relative to an equator (CL) of the tread rubber (10); a third step (S33) of winding and superposing a non-electrically-conductive third rubber strip (GS3) on an outer circumferential surface of the first intermediate layer (21) while moving the third rubber strip (GS3) in the axial direction, to form a first cap layer (31); a fourth step (S34) of winding, in a region on another side in the axial direction relative to the first intermediate layer (21) and the first cap layer (31), an electrically-conductive fourth rubber strip (GS4) from a position of contact with the base layer (1) to an outer circumferential surface of the first cap layer (31), to form an electrically-conductive layer (4); and a fifth step (S35) of winding and superposing, on an outer side in the radial direction of the base layer (1), the third rubber strip (GS3) in a region on the other side in the axial direction relative to the electrically-conductive layer (4) while moving the third rubber strip (GS3) in the axial direction, such that a portion of the electrically-conductive layer (4) is exposed to an outer side in the radial direction of the tread rubber (10), to form a second cap layer (32).
  4. The tread rubber forming method (S3) according to claim 3, wherein a length W2 in the axial direction of the first intermediate layer (21) formed in the second step (S32) is 60% to 80% of a length W1 in the axial direction of the tread rubber (10).
  5. A tread rubber forming device (100, 100B) that spirally winds and superposes tape-shaped unvulcanized rubber strips (GS1, GS2, GS3, and GS4) to form an annular tread rubber (10) according to the method of any one of claims 1 to 4, the device (100, 100B) comprising: a first applicator (111) configured to wind and superpose the first rubber strip (GS1) while moving the first rubber strip (GS1) in an axial direction of the tread rubber (10), to form the base layer (1); a second applicator (112) configured to wind and superpose the non-electrically-conductive second rubber strip (GS2) in a region on one side in the axial direction on an outer circumferential surface of the base layer (1) while moving the second rubber strip (GS2) in the axial direction, to form the first intermediate layer (21); a third applicator (113) configured to wind and superpose the non-electrically-conductive third rubber strip (GS3) on an outer circumferential surface of the first intermediate layer (21) while moving the third rubber strip (GS3) in the axial direction, to form the first cap layer (31); and a fourth applicator (114) configured to wind, in a region on another side in the axial direction relative to the first intermediate layer (21) and the first cap layer (31), the electrically-conductive fourth rubber strip (GS4) from a position of contact with the base layer (1) to an outer circumferential surface of the first cap layer (31), to form the electrically-conductive layer (4).
  6. The tread rubber forming device (100, 100B) according to claim 5, wherein the third applicator (113) winds and superposes, on an outer side in a radial direction of the base layer (1) and the electrically-conductive layer (4), the third rubber strip (GS3) in a region on the other side in the axial direction relative to the electrically-conductive layer (4) while moving the third rubber strip (GS3) in the axial direction, such that a portion of the electrically-conductive layer (4) is exposed to an outer side in the radial direction of the tread rubber (10), to form a second cap layer (32).
  7. The tread rubber forming device (100, 100B) according to claim 6, wherein the second applicator (112) winds and superposes, on the outer circumferential surface of the base layer (1) and an outer circumferential surface of the electrically-conductive layer (4), the second rubber strip (GS2) in a region on the other side in the axial direction relative to the electrically-conductive layer (4) while moving the second rubber strip (GS2) in the axial direction, such that a portion of the electrically-conductive layer (4) is exposed to an outer side in the radial direction of the second rubber strip (GS2), to form a second intermediate layer (22).
  8. The tread rubber forming device (100B) according to any one of claims 5 to 7, further comprising: a pair of cylindrical bodies (101 and 102) which are each exclusively disposed at a first position (P1) or a second position (P2) and on which the rubber strips (GS1, GS2, GS3, and GS4) are wound; and a movement portion (104) configured to move the cylindrical bodies (101 and 102), to mutually exchange the cylindrical bodies (101 and 102) disposed at the respective positions (P1 and P2), wherein the first applicator (111) and the second applicator (112) are arranged at positions corresponding to the first position (P1), and the third applicator (113) and the fourth applicator (114) are arranged at positions corresponding to the second position (P2).
  9. A tread rubber forming device (100C) that spirally winds and superposes tape-shaped unvulcanized rubber strips (GS1A, GS2A, GS3A, GS4A, and GS5A) to form an annular tread rubber (10), the device (100C) comprising: a first applicator (111A) configured to wind and superpose a first rubber strip (GS1A) while moving the first rubber strip (GS1A) in an axial direction of the tread rubber (10), to form a base layer (1); a second applicator (112A) configured to wind and superpose a non-electrically-conductive second rubber strip (GS2A) on an outer circumferential surface of the base layer (1) while moving the second rubber strip (GS2A) in the axial direction, to form an intermediate layer (2); a third applicator (113A) configured to wind an electrically-conductive third rubber strip (GS3A) from a position of contact with the base layer (1) to an outer circumferential surface of the intermediate layer (2), to form a first electrically-conductive layer (41); a fourth applicator (114A) configured to wind and superpose a non-electrically-conductive fourth rubber strip (GS4A) on the outer circumferential surface of the intermediate layer (2) while moving the fourth rubber strip (GS4A) in the axial direction, to form a cap layer (3); and a fifth applicator (115A) configured to wind an electrically-conductive fifth rubber strip (GS5A) from a position of contact with the first electrically-conductive layer (41) to an outer circumferential surface of the cap layer (3), to form a second electrically-conductive layer (42).
  10. The tread rubber forming device (100C) according to claim 9, wherein the second applicator (112A) winds and superposes the second rubber strip (GS2A) in a region on one side in the axial direction on the outer circumferential surface of the base layer (1), to form a first intermediate layer (21), the third applicator (113A) winds, to an outer circumferential surface of the first intermediate layer (21), the third rubber strip (GS3A) in a region on another side in the axial direction relative to the first intermediate layer (21), to form the first electrically-conductive layer (41), and the second applicator (112A) winds and superposes the second rubber strip (GS2A) on the outer circumferential surface of the base layer (1) and an outer circumferential surface of the first electrically-conductive layer (41) such that a portion of the first electrically-conductive layer (41) is exposed to an outer side in a radial direction of the second rubber strip (GS2A), to form a second intermediate layer (22).
  11. The tread rubber forming device (100C) according to claim 10, wherein the fourth applicator (114A) winds and superposes the fourth rubber strip (GS4A) on a portion of the outer circumferential surface of the first intermediate layer (21), to form a first cap layer (31), the fifth applicator (115A) winds, to the outer circumferential surface of the intermediate layer (2), the fifth rubber strip (GS5A) in a region on the other side in the axial direction relative to the first cap layer (31), to form the second electrically-conductive layer (42), and the fourth applicator (114A) winds and superposes the fourth rubber strip (GS4A) on the outer circumferential surface of the intermediate layer (2) and an outer circumferential surface of the second electrically-conductive layer (42) such that a portion of the second electrically-conductive layer (42) is exposed to an outer side in the radial direction of the fourth rubber strip (GS4A), to form a second cap layer (32).
  12. The tread rubber forming device (100C) according to any one of claims 9 to 11, further comprising: a pair of cylindrical bodies (101 and 102) which are each exclusively disposed at a first position (P1) or a second position (P2) and on which the rubber strips (GS1A, GS2A, GS3A, GS4A, and GS5A) are wound; and a movement portion (104) configured to move the cylindrical bodies (101 and 102), to mutually exchange the cylindrical bodies (101 and 102) disposed at the respective positions (P1 and P2), wherein the first applicator (111A) to the third applicator (113A) are arranged at positions corresponding to the first position (P1), and the fourth applicator (114A) and the fifth applicator (115A) are arranged at positions corresponding to the second position (P2).

Description

Field of the Invention The present invention relates to a technology of spirally winding and superposing tape-shaped unvulcanized rubber strips to form an annular tread rubber. Description of the Background Art Conventionally, technologies have been known in which rubber strips are spirally wound and superposed to form a jointless tread rubber so that the uniformity of a tire is improved (see, for example, Japanese Laid-Open Patent Publication No. 2005-35337). Japanese Laid-Open Patent Publication No. 2005-35337 discloses a technology of forming, in a jointless manner, a tread rubber that includes an electrically-conductive band penetrating two rubber layers in the thickness direction. Meanwhile, tread rubbers including three rubber layers have been recently studied to, for example, improve wet performance, low fuel consumption performance, and responsiveness in a balanced manner. However, the technology disclosed in the above-described Japanese Laid-Open Patent Publication No. 2005-35337 has difficulty in forming, in a jointless manner, a tread rubber that includes three rubber layers and an electrically-conductive layer. EP 2 487 051 A1 discloses a tread rubber forming method for the formation of a tread rubber including two rubber layers and an electrically-conductive layer. The tread rubber has a cap portion which is formed by a nonconductive rubber and constructs a ground-contacting surface, a base portion which is formed by a nonconductive rubber and is provided in an inner side in the tire radial direction of the cap portion, and a conductive portion which is formed by a conductive rubber and reaches a bottom surface of the tread rubber from a ground-contacting surface. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a tread rubber forming method and a tread rubber forming device that enable jointless formation of a tread rubber including three rubber layers and an electrically-conductive layer. A first aspect of the present invention is directed to a method for spirally winding and superposing tape-shaped unvulcanized rubber strips on an outer side in a radial direction of a cylindrical body to form an annular tread rubber, the method as recited by Claim 1. It is preferable that, in the tread rubber forming method according to the present first aspect, the fifth step includes winding the third rubber strip in a region that includes the separation portion. A second aspect of the present invention is directed to a method for spirally winding and superposing tape-shaped unvulcanized rubber strips on an outer side in a radial direction of a cylindrical body to form an annular tread rubber, the method as recited by Claim 3. It is preferable that, in the tread rubber forming method according to the present second aspect, a length W2 in the axial direction of the first intermediate layer formed in the second step is 60% to 80% of a length W1 in the axial direction of the tread rubber. A third aspect of the present invention is directed to a device that spirally winds and superposes tape-shaped unvulcanized rubber strips to form an annular tread rubber, the device as recited by Claim 5. It is preferable that, in the tread rubber forming device according to the present third aspect, the third applicator winds and superposes, on an outer side in a radial direction of the base layer and the electrically-conductive layer, the third rubber strip in a region on the other side in the axial direction relative to the electrically-conductive layer while moving the third rubber strip in the axial direction, such that a portion of the electrically-conductive layer is exposed to an outer side in the radial direction of the tread rubber, to form a second cap layer. It is preferable that, in the tread rubber forming device according to the present third aspect, the second applicator winds and superposes, on the outer circumferential surface of the base layer and an outer circumferential surface of the electrically-conductive layer, the second rubber strip in a region on the other side in the axial direction relative to the electrically-conductive layer while moving the second rubber strip in the axial direction, such that a portion of the electrically-conductive layer is exposed to an outer side in the radial direction of the second rubber strip, to form a second intermediate layer. It is preferable that the tread rubber forming device according to the present third aspect further includes: a pair of cylindrical bodies each exclusively disposed at a first position or a second position; and a movement portion configured to move the cylindrical bodies, to mutually exchange the cylindrical bodies disposed at the respective positions, wherein the first applicator and the second applicator are arranged at positions corresponding to the first position, and the third applicator and the fourth applicator are arranged at posit