JP5864501B2 - Mold for tire - Google Patents

Description

  The present invention relates to a mold used in a tire vulcanization process and a method for manufacturing the mold.

  In the tire vulcanization process, a mold is used. As this mold, a split mold or a two-piece mold is used. The split mold includes arc-shaped tread segments (hereinafter simply referred to as segments). A ring-shaped cavity surface is formed by arranging a large number of segments in the circumferential direction.

  In the vulcanization process, a preformed raw cover is put into a mold. The raw cover is heated while being pressurized in a cavity surrounded by the mold and the bladder. The rubber composition of the raw cover flows in the cavity by pressurization and heating. The rubber causes a crosslinking reaction by heating, and a tire is obtained. When air is left between the cavity surface of the mold and the raw cover during pressurization, a bear is formed on the surface of the tire. Bears reduce tire quality.

  Patent Documents 1 to 3 propose so-called spuleless molds as examples of such tire molds. The segment of the mold includes a block in which a plurality of plate-shaped pieces are overlapped, and a holder to which the block is mounted. This block has a cavity surface. A slit is formed between the stacked plate-like pieces. Air is discharged through this slit. The air discharged from the block is further discharged through an opening formed in the holder. Thereby, in these molds, generation of bears is suppressed.

JP 2009-23231 A JP 2012-196973 A JP 2012-250423 A

  The tire tread thickness is not uniform. The thickness of the shoulder region of the tread is thicker than the thickness of the center region. When vulcanized at the optimum vulcanization temperature and vulcanization time for the shoulder region, over-vulcanization may occur in the center region. This overvulcanization may cause deterioration of tire durability and appearance defects. In the vulcanization process, unevenness of vulcanization of the tread tends to occur.

  As a means for uniformly vulcanizing the tread, it can be considered that the thermal conductivity of the shoulder region of the block is made larger than the thermal conductivity of the center region. Due to the difference in thermal conductivity, the vulcanization of the shoulder region and the center region can be made uniform. It is conceivable to use plate-like pieces having different thermal conductivities in the shoulder region and the center region.

  The plate-like pieces having different thermal conductivities have different thermal expansion coefficients. In plate-like pieces having different coefficients of thermal expansion, distortion generated during vulcanization tends to be non-uniform. In the block in which the plate-like pieces are overlapped, distortion also occurs in the slit between the plate-like pieces. The slit gap is very small. This distortion of the slit hinders air discharge. The distortion of the slit causes unvulcanized rubber to enter the slit.

  An object of the present invention is to provide a mold in which a block is securely fixed and generation of bears is suppressed, and to provide a method for manufacturing the mold.

The tire mold according to the present invention is a tire mold in which a cavity surface is formed on the inner surface. This mold includes a block having a plurality of plate-like pieces stacked in the axial direction, a holder having a recess into which the block can be fitted, and a block fitted in the recess to the recess. And a fixing member.
The fixing member includes an engagement groove and an engagement member that engages with the engagement groove. The engaging groove is formed to extend in the axial direction on the radially outer surface of the block. The engaging member is attached to the recess. When the engaging member is passed through the engaging groove, the engaging member and the engaging groove engage from the plate-like piece at one end in the axial direction to the plate-like piece at the other end, and the block is attached to the holder. Yes. The plurality of plate-like pieces are composed of two or more plate-like pieces having different coefficients of thermal expansion.

  Preferably, among the plurality of plate-like pieces, the thermal conductivity of the piece located at the shoulder is made larger than the thermal conductivity of the plate-like piece located at the center.

  Preferably, the engagement member includes a pair of side surfaces facing the circumferential direction and facing the engagement groove. The distance in the circumferential direction between the pair of side surfaces is narrowed from the inside in the radial direction toward the outside. The engagement groove includes a pair of inner surfaces facing the circumferential direction and abutting against a side surface of the engagement member. The circumferential distance between the pair of inner surfaces is narrowed from the inside in the radial direction toward the outside.

  Preferably, the thermal expansion coefficient of the plate-shaped piece is set larger than the thermal expansion coefficient of the engaging member.

  Preferably, the plate-shaped piece is made of an aluminum alloy or a copper alloy. The engaging member is made of steel.

  Preferably, the plate-like piece is made of a copper alloy and an aluminum alloy. The ratio of the copper alloy of the plate-like piece located at the shoulder is set larger than the ratio of the copper alloy of the plate-like piece located at the center.

In the method for manufacturing a tire mold according to the present invention, a plurality of plate-shaped piece base materials, a holder base material, and an engaging member extending in the axial direction are prepared.
This manufacturing method is
A step of stacking a plurality of plate-like piece base materials in the axial direction to form a block base material;
Forming a recess for fitting the block base material to the holder base material,
Forming an engaging groove for engaging with an engaging member in the block base material;
In a state where the engaging member is engaged with the engaging groove of the block base material, the block base material is fitted into the recess of the holder base material, and this engaging member is attached to the holder member so that the segment base material is The resulting process,
A step in which a cavity surface is formed on the block base material of the segment base material to obtain a segment, and a step in which a plurality of the segments are connected in the circumferential direction to form a mold.
In this manufacturing method, the plurality of plate-shaped piece base materials are made of plate-shaped piece base materials having two or more different thermal expansion coefficients.

  In the mold according to the present invention, each of the plurality of plate-like pieces is fixed to the holder. The block is securely fixed to the holder. Since the engaging member is passed through the engaging groove and attached, even if the coefficient of thermal expansion of the plate-like piece of the block is different, the local distortion is suppressed. In this mold, air is easily discharged through a slit formed between plate-like pieces. Intrusion of unvulcanized rubber into this slit is suppressed.

FIG. 1 is a cross-sectional view showing a part of a tire mold according to an embodiment of the present invention. FIG. 2 is a perspective view showing a segment of the mold of FIG. 3A is a plan view showing a block of the segment of FIG. 2, and FIG. 3B is a front view thereof. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is a front view of the holder of the segment of FIG. 7 is a cross-sectional view taken along the line VII-VII of the segment of FIG. FIG. 8 is a cross-sectional view of the segment of FIG. 2 taken along line VIII-VIII. 9 is a cross-sectional view of the segment of FIG. 4 along the line IX-IX. FIG. 10 is a partially enlarged cross-sectional view of the segment of FIG. FIG. 11 is a partially enlarged cross-sectional view of a segment of a mold according to another embodiment of the present invention. 12 is a perspective view of the segment base material of FIG. 2 before assembly. FIG. 13 is a perspective view after the base material of FIG. 12 is assembled. FIG. 14 is an explanatory view showing each state before and after cutting of the base material of FIG.

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

  FIG. 1 is a cross-sectional view showing a part of a tire mold (hereinafter simply referred to as a mold) 1 according to an embodiment of the present invention. The mold 1 includes a number of segments 2, a pair of upper and lower side plates 3, and a pair of upper and lower bead rings 4. The planar shape of the segment 2 is substantially arcuate. In this mold 1, a large number of segments 2 are connected in a ring shape. The number of segments 2 is usually 3 or more and 20 or less. The side plate 3 and the bead ring 4 are substantially ring-shaped. This mold 1 is a so-called “split mold”. In FIG. 1, the symbol R indicates a raw cover.

  FIG. 2 is a perspective view showing the segment 2 of the mold 1. In FIG. 2, the arrow X indicates the radial direction of the mold 1, the arrow Y indicates the axial direction, and the arrow Z indicates the circumferential direction. The direction of the mold 1 shown in FIG. 2 is similarly used in other drawings. The segment 2 includes a holder 5 and a block 6. The block 6 is attached to the holder 5. A plurality of blocks 6 arranged in the circumferential direction may be attached to one holder 5.

  The block 6 has a cavity surface 7. The cavity surface 7 includes a convex portion 8 and a concave portion 9. The convex portion 8 corresponds to the groove of the tire tread. The recess 9 corresponds to a tread block of the tire. A tread pattern is formed on the tire by the convex portions 8 and the concave portions 9. The shape of the convex part 8 and the recessed part 9 is suitably determined according to a tread pattern. In addition, in FIG. 1, illustration of the convex part 8 and the recessed part 9 is abbreviate | omitted.

  FIG. 3A is a plan view showing the block 6 (viewed in the axial direction), and FIG. 3B is a front view thereof (viewed in the radial direction). FIG. 4 is a part of a cross section taken along the line IV-IV in FIG. FIG. 5 is a part of a cross section taken along the line VV in FIG. The block 6 has a cavity surface 7 facing inward in the radial direction, a rear surface 10 facing outward in the radial direction, a pair of split surfaces 11 facing in the circumferential direction, and a pair of end surfaces 29 facing in the axial direction. doing.

  The block 6 includes two end pieces 13 positioned at axial ends and a plurality of intermediate pieces 14 (hereinafter referred to as pieces 14) disposed between two end pieces 13 (hereinafter referred to as pieces 13). And). Each of the pieces 13 and 14 is a plate-like piece. Piece 13 and piece 14 are overlapped in the axial direction. The piece 14 includes a plurality of pieces 14a located on the shoulder side of the tread and a plurality of pieces 14b located on the center side.

  As shown in FIG. 5, each piece 13, 14 (14 a and 14 b) is formed with a bolt hole 15 at a position that coincides with each other when overlapped. Bolts 16 are inserted into the bolt holes 15. Nuts 17 are screwed to both ends of the bolt 16. A counterbore 18 for receiving the nut 17 is formed in the bolt hole 15 of the piece 13. For this reason, neither the bolt 16 nor the nut 17 protrudes from the end surface 29 of the piece 13. As shown in FIG. 3A, in this block 6, all pieces 13 and 14 are fastened by four sets of bolts 16 and a pair of nuts 17.

  In the block 6, a portion formed by the piece 13 and the piece 14 a in the cavity surface 7 forms a shoulder region of the tread. The portion formed by the piece 14b forms the center region of the tread. The piece 13 and the piece 14 are made of, for example, an aluminum alloy or a copper alloy. In this block 6, for example, the piece 13 and the piece 14a are made of a copper alloy. The piece 14b is made of an aluminum alloy. The center region here is a central region in the axial direction straddling the equator plane, and is a region having a width of 0.6 times the tread width, and the shoulder region has a tread width of 0.2 from the end of the tread toward the center region. It is an area of double width. The tread width is measured along the tread surface formed by the cavity surface 7.

  As shown in FIGS. 3A and 3B, a keyway 19 is formed on the back surface 10 of the block 6 (all pieces 13 and 14). As shown in FIG. 3A, a key groove 19 is formed on the end surface 29 at a position avoiding the bolt hole 15 and the counterbore 18. As shown in FIG. 3B, the key groove 19 extends in the axial direction. The keyway 19 extends from one piece 13 in the axial direction to the other piece 13. The keyway 19 is open to the back surface 10.

  The key groove 19 includes a pair of inner surfaces 19a and a bottom surface 19b. The bottom surface 19b is located at the bottom of the keyway 19 and faces outward in the radial direction. The pair of inner surfaces 19a face in the circumferential direction and face each other. The inner surface 19a is formed continuously from the rear surface 10 and the circumferential end of the bottom surface 19b. The inner surface 19a is a plane. The inner surface 19a is inclined from the outer side in the circumferential direction of the key groove 19 toward the inner side from the inner side in the radial direction toward the outer side. The distance between the pair of inner surfaces 19a gradually decreases from the inside in the radial direction toward the outside. In this segment 2, three key grooves 19 are formed in the block 6. The number of key grooves 19 is not limited to three.

  FIG. 6 shows a front view of the holder 5 (viewed in the radial direction). The holder 5 is made of, for example, steel or an aluminum alloy. FIG. 7 shows a cross section taken along line VII-VII in FIG. FIG. 8 shows a cross section taken along line VIII-VIII in FIG.

  As shown in FIGS. 7 and 8, the holder 5 is formed with a recess 21 into which the block 6 can be closely fitted. The recess 21 is defined by a bottom surface 22 and inner surfaces of a pair of opposing side walls 23, and has a channel shape with a substantially rectangular cross section. The recess 21 has a shape complementary to the outer shape of the block 6. The bottom surface 22 of the recess 21 covers the back surface 10 of the block 6, and the side wall 23 of the recess 21 covers the end surface 29 in the axial direction of the block 6 (the end surface of the end piece 13). The dividing surface 11 of the block 6 is exposed.

  The bottom surface 22 of the recess 21 is in contact with the back surface 10 of the block 6 fitted in the recess 21 while forming a slight clearance 30. The inner surface of the side wall 23 of the recess 21 is in contact with the upper and lower end surfaces 29 of the fitted block 6 while forming a slight clearance 30. These clearances 30 can be formed, for example, by forming ridges on the inner surface of the recess 21 and / or the outer surface of the block 6. The protrusions formed on the bottom surface 22 of the recess 21 and / or the back surface 10 of the block 6 are formed, for example, extending in the axial direction from one end in the axial direction to the other end. The protruding ridges extending in the axial direction guide the relative movement between the back surface 10 and the bottom surface 22 in the axial direction.

  As shown in FIG. 7, a hole 24 is formed in the bottom surface 22 of the holder 5. The hole 24 is formed at a position facing the key groove 19 of the block 6. A counterbore 25 is formed on the back surface 5a of the holder 5 at a position through which the hole 24 passes. The hole 24 passes through the bottom surface 22 and the bottom of the spot facing 25. As shown in FIG. 6, the hole 24 and the counterbore 25 are formed at twelve locations. The hole 24 and the counterbore 25 are formed to be spaced apart from each other in the axial direction and the circumferential direction.

  As shown in FIGS. 7 and 8, the segment 2 includes a bolt 26 and a key 27. The bolt 26 and the key 27 are made of a steel material such as carbon steel. As shown in FIG. 8, the key 27 includes a side surface 27a facing in the circumferential direction. The side surface 27a is a plane inclined with respect to the radial direction. The side surface 27a is inclined inward from the outer circumferential side of the key 27 toward the outer side in the radial direction. The distance in the circumferential direction between the pair of side surfaces 27a is narrowed from the inside in the radial direction toward the outside. As shown in FIG. 8, the cross-sectional shape perpendicular to the axial direction of the key 27 is a trapezoid. As shown in FIG. 7, the key 27 extends in the axial direction from one end piece 13 to the other end piece 13. A female screw is formed on the outer surface of the key 27 in the radial direction. The female screw is formed at a position corresponding to the hole 24.

  Bolts 26 are passed through the holes 24. A key 27 is inserted into the keyway 19. A head 26 a of the bolt 26 is accommodated in the counterbore 25. The head 26 a does not protrude from the back surface 5 a of the holder 5. The male screw of the bolt 26 is screwed into the female screw of the key 27. Thereby, the block 6 is fixed to the recess 21. The bolt 26 functions as an attachment for attaching the key 27. In the segment 2 of the mold 1, the key groove 19, the bolt 26 and the key 27 constitute a fixing member.

  The block 6 can be removed from the recess 21 by loosening or removing the bolt 26. As described above, the key groove 19, the bolt 26, and the key 27 fix the block 6 to the recess 21 in a detachable manner.

  As shown in FIGS. 4 and 5, a first shim 28 is sandwiched between adjacent pieces 13 and 14. When the nut 17 is tightened, the pieces 13 and 14 clamp the first shim 28. The first shim 28 forms a first slit 31 between the adjacent pieces 13 and 14. The first slit 31 extends in the radial direction and the circumferential direction. The first slit 31 extends from the cavity surface 7 to the back surface 10. Therefore, the first slit 31 communicates with the clearance 30.

  The first shim 28 is made of a metal such as stainless steel. The first shim 28 has a thin plate shape. The size of the gap of the first slit 31 can be adjusted by the thickness of the first shim 28. The size of the gap between the first slits 31 is measured as an axial distance. The gap between the first slits 31 is set to 0.001 mm or more and 0.5 mm or less. In the mold 1 in which the gap between the first slits 31 is large, air is easily discharged. From this viewpoint, the gap is preferably 0.01 mm or more, and more preferably 0.02 mm or more. On the other hand, in the mold 1 having a small gap, intrusion into the unvulcanized rubber into the first slit 31 is suppressed. From this viewpoint, the gap is preferably 0.09 mm or less, more preferably 0.07 mm or less, and particularly preferably 0.05 mm or less.

  9 is an enlarged cross-sectional view along the line IX-IX in FIG. FIG. 9 shows the intermediate piece 14, the bolts 16, and six first shims 28. As shown in FIG. 9, the planar shape of the first shim 28 is substantially rectangular. The first shim 28 which is rectangular can be easily manufactured. The first shim 28 is arranged avoiding the bolt hole 15 and the key groove 19. The bolt 16 and the key 27 do not penetrate the first shim 28. Since the first shim 28 does not have to have holes for the bolts 16 and the keys 27, the first shim 28 can be easily manufactured.

  As shown in FIG. 10, in this segment 2, the key 27 is attracted to the holder 5 by a bolt 26. The inner surface 19a of the key groove 19 of the piece 14 and the side surface 27a of the key 27 are in pressure contact. Key 27 presses piece 14 radially outward. Thereby, the piece 14 is fixed to the holder 5. Similarly, the piece 13 and the other piece 14 are fixed to the holder 5. In this segment 2, all pieces 13 and pieces 14 from the piece 13 at one end in the axial direction to the piece 13 at the other end are securely fixed to the holder 5.

  The inner surface 19a of the key groove 19 and the side surface 27a of the key 27 are pressed against each other, and a frictional resistance is generated in the movement of the pieces 13 and 14 in the axial direction. The movement of all pieces 13 and pieces 14 in the axial direction is similarly suppressed.

  In the tire tread, the thickness of the shoulder region is larger than the thickness of the center region. The optimum vulcanization time differs between the tread shoulder region and the center region. In this block 6, the piece 13 and the piece 14a located in the shoulder region are made of a copper alloy. The piece 14b located in the center region is made of an aluminum alloy. The thermal conductivity of the piece 13 and the piece 14a is made larger than the thermal conductivity of the piece 14b. Thereby, the shoulder region and the center region can be vulcanized more uniformly.

  Here, the example in which the piece 13 and the piece 14a are made of a copper alloy and the piece 14b is made of an aluminum alloy has been described, but the piece 13, the piece 14a and the piece 14b are made of a copper alloy and an aluminum alloy, The ratio of the copper alloy of 13 and piece 14a may be made larger than the ratio of the copper alloy of piece 14b. The thermal conductivity of piece 13 and piece 14a should just be made larger than the thermal conductivity of piece 14b.

  The thermal expansion coefficients of the piece 13 and the piece 14a are different from the thermal expansion coefficient of the piece 14b. The whole piece 13 and piece 14 are fixed by a key 27. Unlike the configuration in which a part of the piece 13 and the piece 14 is fixed to the holder, in the block 6, the distortion generated during heating is suppressed from being concentrated on a part of the pieces 13 and 14. The deformation of the first slit 31 between the piece 13 and the piece 14 is suppressed. The smaller the gap between the first slits 31, the more easily the size of the gap changes due to deformation. In this segment 2, the unvulcanized rubber is prevented from entering the first slit 31. Air is exhausted sufficiently during vulcanization. A tire without spew is obtained by the mold 1 having no vent hole.

  The thermal expansion coefficients of the pieces 13 and 14 are larger than those of the bolt 26 and the key 27. Since the inner surface 19a of the key groove 19 is in contact with the side surface 27a of the key 27, the block 6 is pressed against the holder 5 even during heating. During vulcanization, loosening between the block 6 and the holder 5 is suppressed.

FIG. 11 is a partial sectional view of a mold 41 according to another embodiment of the present invention.
The segment 42 of the mold 41 includes a block 43 and a key 44. The mold 41 has the same configuration as the mold 1 except that it includes a block 43 and a key 44 instead of the block 6 and the key 27 of the mold 1. Here, of the configuration of the mold 41, the configuration different from the mold 1 will be described, and the description of the same configuration as the mold 1 will be omitted. Here, the same components as those of the mold 1 will be described using the same reference numerals.

  The block 43 includes a key groove 45 instead of the key groove 19 of the block 6. Although not shown, the other configuration of the block 43 is the same as that of the block 6. The keyway 45 of the block 43 is open to the back surface 43 a of the block 43. The key groove 45 is formed so as to penetrate all the pieces in the axial direction. The cross-sectional shape perpendicular to the axial direction of the key groove 45 is a T-shape.

  The key 44 extends in the longitudinal direction in the axial direction. The cross-sectional shape perpendicular to the axial direction of the key 44 is rectangular. The key 44 is passed through the key groove 45. The keys 44 are all engaged with the pieces in the axial direction.

  The key 44 is attracted to the holder 5 by the bolt 26. The keyway 45 and the key 44 are in pressure contact. The key 44 presses the block 43 outward in the radial direction. Thereby, the block 43 is fixed to the holder 5. All the pieces from the one end piece in the axial direction to the other end piece are fixed to the holder 5 respectively. In the segment 42, all the pieces are securely fixed to the holder 5.

  The block 43 is formed with an edge 46 that sandwiches the opening of the key groove 45. This edge 46 is sandwiched between and pressed against the key 45 and the holder 5. Due to this pressure contact, movement of all pieces of the block 43 in the axial direction is suppressed.

  Also in this segment 42, since the whole piece 13 is fixed by the key 45, it is suppressed that the distortion which arises at the time of a heating concentrates on some pieces. The deformation of the first slit 31 is suppressed.

  In particular, in the above-described mold 1, the key 27 and the holder 5 are fixed without sandwiching a part of the end piece 13 and the intermediate piece 14 in the axial direction of the bolt 26. Compared to the mold 41, the mold 1 is restrained from causing local distortion in the pieces 13 and 14. In the mold 1, the deformation of the first slit 31 is further suppressed as compared with the mold 41.

  In the mold 1, the uneven pattern may not be formed on the cavity surface 7. A slick tire and a plain tire can be obtained by the mold 1 having no uneven pattern. Spew is also suppressed in this slick tire and plain tire. The surface of the plain tire is cut to form an uneven pattern. Since there is little spew, it is easy to cut this plain tire.

  The manufacturing method of the mold 1 is outlined with reference to FIGS. A base material (referred to as a holder base material) 32 of the holder 5, a base material (referred to as an end piece base material) 33 of the end piece 13, a base material (referred to as an intermediate piece base material) 34 of the intermediate piece 14, and a bolt 26 And a key 27 are prepared.

  The manufacturing method of the mold 1 includes a step of forming a block base material 36, a step of forming the recess 21 in the holder base material 32, a step of forming the key groove 19 in the block base material 36, and a segment base material 37. Including the step of obtaining the segment 2, the step of obtaining the segment 2, and the step of forming the mold 1.

  In the step of forming the block base material 36, the plurality of plate-like piece base materials 33 and 34 are overlapped in the axial direction to form the block base material 36. The piece base materials 33 and 34 are plate-shaped. The planar shape of the piece base materials 33 and 34 is a shape in which one side of the rectangle is formed in an arc shape. The radius of curvature of this arc is substantially equal to the radius of curvature of the bottom surface 22 of the recess 21. Two piece base materials 33, a plurality of piece base materials 34, and a plurality of first shims 28 are laminated. Bolts 16 are inserted into the bolt holes 15 and nuts 17 are tightened. Thereby, all the piece base materials 33 and 34 are fastened, and the block base material 36 is formed. A counterbore 18 is further formed on the end piece base material 33. In the block base material 36, a large number of piece base materials 33 and 34 and a large number of first shims 28 are alternately stacked. The piece base materials 33 and 34 and the first shim 28 are integrated by a bolt 16 and a nut 17.

  In the step of forming the recess 21 in the holder base material 32, the recess 21 is formed by cutting. FIG. 12 shows a holder base material 32 in which a recess 21 is formed. The recess 21 is for fitting the block base material 36. The bottom surface 22 of the recess 21 has a partial cylindrical shape. In the cross section perpendicular to the axial direction, the bottom surface 22 extends in an arc shape. In the holder base material 32, a pair of side walls 23 that are opposed to each other in the axial direction across the bottom surface 22 are provided upright. A hole 24 is formed in the bottom surface 22. Although not shown, a counterbore is formed on the back surface of the holder base material 32. A hole 24 is formed on the bottom face of the counterbore so as to penetrate from the bottom face 22. The holder base material 32 is preferably formed in a rectangular parallelepiped shape from a forged aluminum alloy.

  In the step of forming the key groove 19 in the block base material 36, the key groove 19 is formed on the back surface 10 of the block base material 36. The back surface 10 has a shape made into a partial columnar shape. A keyway 19 is formed in the end piece base material 33 and the intermediate piece base material 34.

  In the process of obtaining the segment base material 37, the key 27 is inserted into the key groove 19 of the block base material 36. With the key 27 inserted and engaged, the block base material 36 is fitted into the recess 21 of the holder base material 32. A bolt 26 is passed through the hole 24 of the holder base material 32, and the bolt 26 is screwed into the key 27. The key 27 is attracted to the holder base material 32. The block base material 36 is drawn to the holder base material 32 via the key 27. A block base material 36 is attached to the holder base material 32. In this way, the block base material 36 and the holder base material 32 are fixed to form the segment base material 37.

  In the process of obtaining the segment 2, both end surfaces of the segment base material 37 are cut into an inclined shape as indicated by a two-dot chain line in FIG. 13. The hatched portion in FIG. 14 is cut by cutting. A segment (white background portion in the figure) 2 is formed by this cutting process. The counterbore 25 of the holder 5 is formed from the counterbore formed in the holder base material 32 by this cutting process. By this cutting process, the cavity surface 7 having a concavo-convex pattern is formed on the block base material 36. In this method, the concavo-convex pattern is directly carved. A typical cutting process is cutting with a tool. Cutting may be performed by high energy density processing. Specific examples of the high energy density machining include electrolytic machining, electric discharge machining, wire cut electric discharge machining, laser machining, and electron beam machining. Since the concavo-convex pattern is directly carved, the degree of freedom of the shape of the concavo-convex pattern is high. The dimensional accuracy of this uneven pattern is high. Segment 2 is obtained by this cutting process.

  In the process of forming the mold 1, the plurality of segments 2 are connected in the circumferential direction. These segments 2, a pair of upper and lower side plates 3, and a pair of upper and lower bead rings 4 are combined to form a mold 1.

  In the tire manufacturing method using this mold 1, a raw cover is prepared by preforming. The raw cover is put into the mold 1 in a state where the mold 1 is open and the bladder is contracted. At this stage, the raw cover rubber composition is in an unvulcanized state. The mold 1 is tightened and the bladder expands. The raw cover is pressed against the cavity surface 7 of the mold 1 by a bladder and pressurized. The raw cover R in this state is shown in FIG. At the same time, the raw cover is heated. The rubber composition flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and a tire is obtained. The process in which the raw cover is pressurized and heated is referred to as a vulcanization process.

  As described above, since the first slit 31 is exposed to the cavity surface 7, the air between the raw cover and the cavity surface 7 moves through the first slit 31 in the vulcanization process. The air reaches the dividing surface 11 and is discharged. Air can also be discharged through the bolt hole 15 and the keyway 19. By discharging air, bear is prevented. In the mold 1, air can be sufficiently discharged even if a vent hole is not provided. A tire without spew is obtained by the mold 1 having no vent hole. This tire is excellent in appearance and initial grip performance. A small number of vent holes may be provided together with the first slit 31.

  When the mold 1 is used repeatedly, deposits adhere to the cavity surface 7. This deposit impairs the tire quality. The deposit needs to be removed. For removal, the block 6 is removed from the recess 21 of the holder 5 after the bolt 26 has been loosened or removed. Next, the bolts 16 are extracted from the block 6 and disassembled into pieces 13 and 14. After each part is cleaned, the segment 2 is assembled in the reverse procedure.

  The mold according to the present invention is suitable for manufacturing various tires.

DESCRIPTION OF SYMBOLS 1 ... Mold 2 ... Segment 3 ... Side plate 4 ... Bead ring 5 ... Holder 6 ... Block 7 ... Cavity surface 8 ... Convex part 9 ... Concave part 10 ... Back 11 ... Dividing surface 13 ... End piece 14 ... Intermediate piece 15 ... Bolt hole 16 ... Bolt 17 ... Nut 18 ... Counterbore 19 ... Key Groove 21 ... Recess 22 ... Bottom 23 ... Side wall 24 ... Hole 25 ... Counterbore 26 ... Bolt 27 ... Key 28 ... First shim 29 ... End face 30 ... Clearance 31 ... First slit 32 ... Holder base material 33 ... End piece base material 34 ... Intermediate piece base material 36 ... Block base material 37 ... Segment base material 41 ... Mold 42 ... Segment 43 ... Click 44 ... key 45 ... key groove 46 ... edge

Claims (8)

A tire mold having a cavity surface formed on the inner surface,
A block having a plurality of plate-like pieces stacked in the axial direction in the plate thickness direction ;
A holder having a recess into which the block can be fitted;
A fixing member for fixing the block fitted in the recess to the recess;
The fixing member includes an engagement groove and an engagement member that engages with the engagement groove.
This engaging groove is formed to extend in the axial direction on the radially outer surface of the block,
This engaging member is attached to the recess and extends in the axial direction ,
When the engaging member is passed through the engaging groove, the engaging member and the engaging groove engage from the plate-like piece at one end in the axial direction to the plate-like piece at the other end, and the block is attached to the holder. And
The plate-like piece is sandwiched between the engagement member and the recess in the radial direction,
The thermal expansion coefficient of the plate-shaped piece is larger than the thermal expansion coefficient of the engaging member,
A tire mold in which a plurality of plate-shaped pieces are composed of two or more plate-shaped pieces having different coefficients of thermal expansion. The back surface of the block and the bottom surface of the recess that covers the back surface are in a complementary shape,
  The tire mold according to claim 1, wherein a back surface of the block and a bottom surface of the recess are formed in an arc shape when viewed in the axial direction.   3. The tire mold according to claim 1, wherein a protrusion extending in the axial direction is formed on at least one of the bottom surface of the recess and the back surface of the block. The tire according to any one of claims 1 to 3, wherein a thermal conductivity of a plate-like piece located at a shoulder among the plurality of plate-like pieces is larger than a thermal conductivity of a plate-like piece located at a center. Mold. The engagement member has a pair of side surfaces facing the engagement groove facing the circumferential direction, and a circumferential distance between the pair of side surfaces is narrowed from the radially inner side to the outer side,
The engagement groove includes a pair of inner surfaces that face the circumferential direction and contact the side surfaces of the engagement member, and a circumferential distance between the pair of inner surfaces is narrowed from the radially inner side toward the outer side. The mold for tires in any one of Claim 1 to 4 . The plate-shaped piece is made of an aluminum alloy or a copper alloy,
The tire mold according to any one of claims 1 to 5, wherein the engaging member is made of steel. Claims 1, the plate-like piece is the ratio of the copper alloy plate piece which is located above shoulder has become a copper alloy and aluminum alloy is greater than the ratio of the copper alloy plate pieces situated in the center 6 The mold for tires in any one of . A plurality of plate-shaped piece base materials, a holder base material, and an engaging member extending in the axial direction are prepared,
A step of forming a block base material by stacking a plurality of plate-like piece base materials in the axial direction and overlapping the plate thickness direction ;
Forming a recess for fitting the block base material to the holder base material,
Forming an engaging groove extending in the axial direction to engage with an engaging member in the block base material;
The engaging member is engaged with the engaging groove of the block base material, and the engaging groove and the engaging member are engaged from the plate-shaped piece base material at one end in the axial direction to the plate-shaped piece base material at the other end. In this state, the block base material is fitted into the recess of the holder base material, and this engagement member is attached to the holder member to obtain the segment base material.
A step of forming a cavity surface by forming a cavity surface on the block base material of the segment base material, and a step of forming a mold by connecting a plurality of the segments in the circumferential direction,
The plate-shaped piece base material is sandwiched between the engagement member and the recess in the radial direction,
The thermal expansion coefficient of the plate-shaped piece base material is larger than the thermal expansion coefficient of the engaging member,
A method for manufacturing a tire mold, wherein the plurality of plate-like piece base materials are made of plate-like piece base materials having two or more different thermal expansion coefficients.

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