JP2011073262A - Cutting apparatus for cord-containing sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting apparatus 58 for a sheet 56 capable of contributing to manufacture of high-quality tires. <P>SOLUTION: The cutting apparatus 58 is constructed so as to cut the sheet 56 containing a large number of cords 50 arranged in parallel and includes a stretcher 62 and scissors 64. The stretcher 62 can form small-diameter parts 80 in the cords 50 by stretching a part of each cord 50. The scissors 64 can cut the cords 50 in the small-diameter parts 80. A ply formed by the cutting apparatus 58 has a sufficiently high area ratio of the topping rubber 52 occupying the side surface, and the side surface of the ply thus allows sufficient adhesion to another members. In tires produced by using the ply, occurrence of loose is prevented effectively, and the cutting apparatus 58 can contribute to production of high-quality tires. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cutting apparatus for a cord-containing sheet. Specifically, the present invention relates to an apparatus for cutting a sheet including a large number of cords arranged in parallel to form a ply.

  The pneumatic tire includes a belt between the tread and the carcass. This belt is laminated with the carcass. This belt usually consists of two plies. Each ply is composed of a large number of cords arranged in parallel and a topping rubber.

  The cord is formed by twisting a plurality of filaments. A typical material for this filament is steel. From the viewpoint that the cord can be well bonded to the rubber, the surface of each filament may be plated. An example in which such a cord is used for a strip-like sheet incorporated in a tire belt is disclosed in JP-A-10-6711.

  The ply is formed as follows. The topping rubber is pushed out together with the numerous cords that are aligned, and a sheet is formed. This sheet is supplied to a cutting device and cut.

  FIG. 10 is a schematic diagram showing a cutting state of the sheet 4 by the conventional cutting device 2. 11 is a cross-sectional view taken along line XI-XI in FIG. The cutting device 2 includes a stage 6 on which a sheet 4 is placed and a ridge 8. The casket 8 includes two disks 10. The upper disk 10a can rotate in the direction indicated by the arrow A. The lower disk 10b can rotate in the direction indicated by the arrow B. In the cutting apparatus 2, the sheet 4 is cut by moving the collar 8 in the direction indicated by the arrow C while the two disks 10 rotate. By this cutting, the ply 12 is obtained. An example of such a cutting device 2 is disclosed in Japanese Patent Laid-Open No. 6-155632.

Japanese Patent Laid-Open No. 10-6711 JP-A-6-155632

  FIG. 12 is a side view showing a part of the ply 12 obtained by cutting the sheet 4. A side surface of the ply 12 includes a cut surface of the cord 14. The cord 14 is composed of four filaments 16. A plating layer 18 is formed on the peripheral surface of each filament 16. For this reason, this cord 14 can adhere | attach well with the topping rubber 20 located in the circumference | surroundings.

  The distance between the cords 14 is usually equal to or less than the outer diameter of the cords 14. For this reason, more than half of the side surface of the ply 12 is formed by the cut surface of the cord 14. As shown in the drawing, the filament 16 is exposed at the cut surface. The exposed filament 16 is not plated. Since the area ratio of the cut surface of the cord 14 occupying the side surface of the ply 12 is large, this exposure hinders adhesion between the side surface of the ply 12 and another rubber. Insufficient adhesion results in looseness. This looseness affects the durability of the tire.

  From the viewpoint of improving durability, a rubber strip may be provided at the end of the belt. Since the rubber strip restrains the end of the belt, the occurrence of looseness is prevented. However, the addition of this rubber strip increases the tire mass. This rubber strip increases the rolling resistance.

  From the viewpoint of improving durability, a band in which a cord is spirally wound in the circumferential direction may be provided at the end of the belt. Since this band restrains the end of the belt, the occurrence of looseness is prevented. However, the addition of this band increases the tire mass. This band increases the rolling resistance.

  In the strip-like sheet described in JP-A-10-6711, from the viewpoint of improving the durability of the tire, the cut surface of the cord included in the side surface is plated. Since the ply includes a large number of cords, it takes time to perform the plating process on the cut surface of each cord. Such plating treatment hinders tire productivity.

  An object of the present invention is to provide a sheet cutting apparatus that can contribute to the production of high-quality tires.

  The tire sheet cutting apparatus according to the present invention is configured to be able to cut a sheet including a large number of cords arranged in parallel. This cutting device includes a stretcher and a heel. The stretcher can stretch a part of each cord and form a narrow portion in the cord. The scissors can cut the cord at the small diameter portion.

The tire manufacturing method according to the present invention includes:
(1) A step of supplying a sheet including a plurality of cords arranged in parallel to a cutting device that includes a stretcher and a scissors, and the stretcher includes a main body;
(2) a step in which the stretcher stretches a part of each cord and forms a narrow diameter portion in the cord;
(3) a step of cutting the cord at the small diameter portion to form a ply;
(4) obtaining a raw cover including the ply;
And (5) putting the raw cover into a mold, and pressurizing and heating in the mold.

  Preferably, in this tire manufacturing method, the ratio of the area of the cut surface of the cord to the cross-sectional area of the cord is 25% or less.

  In the tire sheet cutting apparatus according to the present invention, the sheet is cut after the cord is stretched. Since the cord is cut at the small diameter portion, the area ratio of the cut surface of the cord occupying the side surface of the ply is smaller than that when the sheet is cut without forming the small diameter portion. Since the side surface of the ply can be sufficiently adhered to other members, the tire manufactured using the ply can prevent the occurrence of looseness. This tire is excellent in durability. This cutting device can contribute to the production of high-quality tires.

FIG. 1 is a cross-sectional view illustrating a part of a pneumatic tire manufactured by a method for manufacturing a tire according to an embodiment of the present invention. FIG. 2 is a perspective view showing a part of a belt constituting the tire of FIG. FIG. 3A is a front view of a cord included in the belt, and FIG. 3B is a side view thereof. FIG. 4 is a schematic diagram illustrating a sheet cutting state by the cutting apparatus. FIG. 5 is a cross-sectional view taken along line VV in FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a schematic diagram showing the formation state of the raw cover. FIG. 9 is a side view showing a part of a ply formed by cutting a sheet. FIG. 10 is a schematic diagram showing a sheet cutting state by a conventional cutting apparatus. 11 is a cross-sectional view taken along line XI-XI in FIG. FIG. 12 is a side view showing a part of the ply obtained by cutting the sheet.

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

  The pneumatic tire 22 shown in FIG. 1 includes a tread 24, a sidewall 26, a bead 28, a carcass 30, a belt 32, an inner liner 34, and a chafer 36. The tire 22 is a tubeless type. The tire 22 is attached to a passenger car. In FIG. 1, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The tire 22 has a substantially bilaterally symmetric shape with the one-dot chain line CL in FIG. 1 as the center. This alternate long and short dash line CL represents the equator plane of the tire 22.

  The tread 24 is made of a crosslinked rubber having excellent wear resistance. The tread 24 has a shape protruding outward in the radial direction. The tread 24 includes a tread surface 38. The tread surface 38 is in contact with the road surface. A groove 40 is carved in the tread surface 38.

  The sidewall 26 extends substantially inward in the radial direction from the end of the tread 24. The sidewall 26 is made of a crosslinked rubber.

  The bead 28 is located substantially inward of the sidewall 26 in the radial direction. The bead 28 includes a core 42 and an apex 44 that extends radially outward from the core 42. The core 42 has a ring shape. The core 42 is formed by winding a non-stretchable wire. The apex 44 is made of a highly hard crosslinked rubber.

  The carcass 30 includes a carcass ply 46. The carcass ply 46 is bridged between the beads 28 on both sides, and extends along the inside of the tread 24 and the sidewall 26. The carcass ply 46 is folded around the core 42 from the inner side in the axial direction to the outer side. Although not shown, the carcass ply 46 includes a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is usually 70 ° to 90 °. In other words, the carcass 30 has a radial structure. The cord is usually made of organic fibers.

  The belt 32 is located on the radially outer side of the carcass 30. The belt 32 is laminated with the carcass 30. The belt 32 reinforces the carcass 30. In the tire 22, the belt 32 includes two plies 48.

  As shown in FIG. 2, each ply 48 includes a large number of cords 50 arranged in parallel and a topping rubber 52. Each cord 50 is inclined with respect to the equator plane. In the tire 22, the inclination direction of the cord 50a included in the ply 48a located on the inner side in the radial direction is opposite to the inclination direction of the cord 50b included in the ply 48b located on the outer side. In FIG. 2, the angle α represents an inclination angle formed by the cord 50a with respect to the equator plane. The angle β represents an inclination angle formed by the cord 50b with respect to the equator plane. In the tire 22, the absolute value of the inclination angle α is not less than 10 ° and not more than 35 °. The absolute value of the inclination angle β is not less than 10 ° and not more than 35 °. The outer diameter of the cord 50 is not less than 0.15 mm and not more than 2.0 mm. The density of the cord 50 is not less than 10/5 cm and not more than 50/5 cm. The density of the cord 50 is obtained by measuring the number (ends) of the cords 50 existing per 5 cm width of the ply 48 in a cross section perpendicular to the longitudinal direction of the cords 50.

  Shown in FIG. 3 is a cord 50 included in the ply 48. FIG. 3A shows the tip of the cord 50. FIG. 3B shows the side surface of the cord 50. In the tire 22, the cord 50 is configured by twisting four filaments 54. A preferred material for each filament 54 is steel. Although not shown, the surface of the filament 54 is brass-plated. This plating can contribute to adhesion between the cord 50 and the topping rubber 52.

  In the method for manufacturing the tire 22, the ply 48 is prepared as follows. The topping rubber 52 is pushed out together with a number of the cords 50 that are aligned, and a sheet 56 as shown in FIG. 4 is formed. The sheet 56 includes a large number of cords 50 arranged in parallel. The sheet 56 is supplied to the cutting device 58 shown in FIGS. A cross-sectional view taken along line VI-VI in FIG. 5 is shown in FIG.

  The cutting device 58 includes a pair of chucks 60, a stretcher 62, and a collar 64. Both chucks 60 are arranged at a predetermined interval. The stretcher 62 and the collar 64 are located between both chucks 60. In the cutting device 58, the stretcher 62 and the collar 64 are configured to be able to move between the chucks 60 in the direction indicated by the arrow D. In FIG. 6 and FIG. 7 described later, what is indicated by a double arrow W is an interval of the chuck 60.

  Each chuck 60 includes an upper jaw 66, a lower jaw 68, and a stage 70. As shown in FIG. 4, the upper jaw 66 is an elongated plate. The upper jaw 66 extends from one end of the sheet 56 to the other end. The lower jaw 68 is located below the upper jaw 66. Although not shown, the lower jaw 68 extends from one end of the sheet 56 to the other end. In the cutting device 58, the lower jaw 68 and the stage 70 are integrally formed. The sheet 56 is placed on the lower jaw 68 and the stage 70. An upper jaw 66 is placed on the sheet 56.

  The stretcher 62 includes a disk-shaped main body 72 and a number of partitions 74. These partitions 74 project radially outward from the outer edge 76 of the main body 72. These partitions 74 are arranged at equal intervals in the circumferential direction. Each partition 74 has a shape that tapers radially outward. The tip of the partition 74 is pointed. The stretcher 62 can rotate in the direction indicated by the arrow E. A point P1 represents the center of rotation of the stretcher 62.

  The collar 64 is located behind the stretcher 62 in the movement direction D. The collar 64 includes a pair of disks 78. The upper disk 78a can rotate in the direction indicated by the arrow F. Point P2 represents the center of rotation of the upper disk 78a. The lower disk 78b can rotate in the direction indicated by the arrow G. Point P3 is the center of rotation of the lower disk 78b. As shown in the drawing, the lower end portion of the upper disc 78a and the upper end portion of the lower disc 78b overlap each other.

  In the cutting device 58, the sheet 56 placed on the stage 70 is sandwiched between the upper jaw 66 and the lower jaw 68. As shown in FIG. 6, the lower surface of the upper jaw 66 has a shape that can be brought into contact with the sheet 56 to bend the sheet 56. The lower jaw 68 is configured such that the upper surface thereof corresponds to the lower surface of the upper jaw 66. For this reason, in the sheet | seat 56 clamped by the upper jaw 66 and the lower jaw 68, the code | cord | chord 50 is fully restrained. In the cutting device 58, both chucks 60 can grip the sheet 56 and hold a large number of cords 50 included in the sheet 56. In the cord 50 held in this way, a portion located between both chucks 60 is pulled with a predetermined force.

  The stretcher 62 moves from one end of the sheet 56 toward the other end while rotating. By this rotation, the partition 74 of the stretcher 62 comes into contact with the sheet 56. The partition 74 pierces the topping rubber 52 of the sheet 56. Since the pitch of the partition 74 is equal to the pitch of the cord 50, the cord 50 is fitted between one partition 74 and another partition 74 adjacent to the one partition 74. By this fitting, the cord 50 comes into contact with the main body 72 of the stretcher 62. When the stretcher 62 moves while rotating further, the main body 72 pushes up the cord 50 at the outer edge 76 thereof.

  7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 7 shows a situation where the stretcher 62 pushes up the cord 50. As shown in the drawing, a part of the cord 50 is stretched by pushing up the main body 72 of the stretcher 62. By this stretching, a part of the cord 50 is plastically deformed, and a narrow diameter portion 80 is formed in the cord 50. By moving the stretcher 62 while rotating further, the partition 74 is pulled out from the sheet 56.

  The collar 64 follows the stretcher 62 and moves from one end of the sheet 56 toward the other end while the two disks 78 rotate. A sheet 56 including a cord 50 having a small diameter portion 80 is supplied to the flange 64. The flange 64 cuts the cord 50 at the small diameter portion 80. In this way, the collar 64 cuts the sheet 56 and the ply 48 is formed.

  In this manufacturing method, the ply 48 is supplied to the former together with members such as the carcass ply 46 and the tread 24. In this former, after the carcass ply 46 is wound, the ply 48 is laminated on the carcass ply 46.

  FIG. 8 shows a ply 48 laminated on the carcass ply 46. As shown in the figure, in this manufacturing method, one end 82a of the ply 48 and the other end 82b are joined together to form the belt 32. In the belt 32 formed in this way, the side surface 84 of the ply 48 constitutes the end of the belt 32. Although not shown, the tread 24 is laminated on the belt 32. The end of the belt 32 is covered with the tread 24. In this way, members such as the carcass ply 46 and the tread 24 are assembled, and a raw cover including the belt 32 formed from the ply 48 is obtained.

  In this manufacturing method, the raw cover is put into a mold held at a predetermined temperature. The raw cover is pressed between the cavity surface of the mold and the outer surface of the bladder. The raw cover is heated by heat conduction from the bladder and the mold. While the rubber composition of the low cover flows by the pressurization and heating, the rubber composition causes a crosslinking reaction, and the tire 22 is obtained.

  In FIG. 9, the side surface 84 of the ply 48 is shown. The side surface 84 includes a cut surface of the cord 50. In this manufacturing method, the cord 50 is cut at the small diameter portion 80. For this reason, the area ratio of the cut surface of the cord 50 occupying the side surface 84 of the ply 48 is the case where the sheet 4 is cut without forming the small diameter portion 80 using the conventional cutting device 2 (see FIG. 12). It is small enough compared to that of). In other words, the area ratio of the topping rubber 52 occupying the side surface 84 of the ply 48 is sufficiently large. In the tire 22, the side surface 84 of the ply 48 can sufficiently adhere to the tread 24 as another member, so that the occurrence of looseness at the end of the belt 32 is effectively prevented. The tire 22 is excellent in durability. This cutting device 58 can contribute to the production of high-quality tires 22.

  In this manufacturing method, the ratio RA of the area of the cut surface of the cord 50 to the cross-sectional area of the cord 50 in the cutting direction of the sheet 4 is preferably 25% or less. By setting the ratio RA to 25% or less, the side surface 84 of the ply 48 can be sufficiently adhered to the tread 24. In the tire 22 manufactured using the ply 48, the occurrence of looseness at the end of the belt 32 is effectively prevented. The tire 22 is excellent in durability. This cutting device 58 can contribute to the production of high-quality tires 22. In this respect, the ratio RA is more preferably 20% or less, further preferably 15% or less, and particularly preferably 10% or less. The area of the cut surface of the cord 50 is indicated by the sum of the areas of the cut surfaces of the filaments 54 included in the cut surface. The cross-sectional area of the cord 50 is indicated by the sum of the cross-sectional areas of the filaments 54 included in the cord 50 in the cutting direction of the sheet 4. The cross-sectional area of the filament 54 is obtained based on the filament 54 that is not in the small diameter portion 80 of the cord 50.

  In this manufacturing method, the ratio RB of the area of the topping rubber 52 on the side surface 84 of the ply 48 to the area of the cut surface of the cord 50 is preferably 1000% or more. By setting the ratio RB within the above range, the side surface 84 of the ply 48 can be sufficiently adhered to the tread 24. In the tire 22 manufactured using the ply 48, the occurrence of looseness at the end of the belt 32 is effectively prevented. The tire 22 is excellent in durability. This cutting device 58 can contribute to the production of high-quality tires 22. In this respect, the ratio RB is more preferably 1300% or more, further preferably 2800% or more, and particularly preferably 14000% or more.

  In FIG. 5, the double-headed arrow HA represents the height from the lower end 86 of the cord 50 included in the sheet 56 before being put into the stretcher 62 to the upper end 88 of the main body 72 of the stretcher 62. In this manufacturing method, from the viewpoint that the cord 50 is effectively stretched, the ratio of the height HA to the interval W of the chuck 60 (see FIGS. 6 and 7) is preferably 0.883 or more, and 0.889 or more. Is more preferable.

  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 sheet formed by extruding a topping rubber together with a number of aligned cords was supplied to a cutting apparatus having the basic configuration shown in FIGS. Each chuck grabbed the sheet and the cords were held. The body of the stretcher stretched a part of each cord at its outer edge, and a narrow portion was formed in this cord. A scissors cut the cord at the small diameter portion to form a ply. The ply was assembled with a member such as a tread, and a raw cover including the ply was formed. The raw cover was put into a mold, and the raw cover was pressurized and heated in the mold. The pneumatic tire shown in FIG. 1 was manufactured by this pressurization and heating. The tire size was 205 / 55R16. As this cord, a cord formed by twisting four filaments was used. The outer diameter of the filament was 0.27 mm. The cross-sectional area of this cord is 0.23 mm ² . The ratio RA of the area of the cut surface of the cord to the cross-sectional area of the cord was 25%. The area of the cut surface of the cord was 0.057 mm ² . The ratio RB of the area of the topping rubber on the side surface of the ply to the area of the cut surface of the cord was 1080%. The cord density in this ply was 40 / 5cm.

[Example 2]
Tires were manufactured in the same manner as in Example 1 except that the ratio RA and the ratio RB were changed.

[Comparative Example 1]
A tire was manufactured in the same manner as in Example 1 except that a ply was formed using a conventional cutting device.

[durability]
The tire was incorporated into a regular rim, and the tire was filled with air to adjust the internal pressure to 230 kPa (standard internal pressure). This tire was mounted on a drum-type running test machine, and a load corresponding to 150% of the reference load (5.64 kN) was applied to the tire. This tire was run on a drum having a radius of 1.7 m at a speed of 80 km / h. After traveling 30000 km, the tire was disassembled and the occurrence of looseness at the end of the belt was confirmed. When the occurrence of loose was confirmed, the maximum length of this loose was measured. The results are shown in Table 1 below as an index. In Table 1, “Y” indicates that looseness is recognized, and “N” indicates that looseness is not recognized.

  As shown in Table 1, the manufacturing method of the example has a higher evaluation than the manufacturing method of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The method described above can be applied to the manufacture of various tires.

2, 58 ... Cutting device 4, 56 ... Sheet 6, 70 ... Stage 8, 64 ... 鋏 10, 78, 78a, 78b ... Disc 12, 48 ... Ply 14, 50 ... Cord 16, 54 ... Filament 18 ... Plating layer 20, 52 ... Topping rubber 22 ... Tire 24 ... Tread 26 ... Side wall 28 ... Bead 30 ... Carcass 32 ... Belt 60 ... Chuck 62 ... Stretcher 76 ... Outer edge 80 ... Small diameter part 84 ... Side

Claims (3)

It is configured so that a sheet containing a large number of parallel codes can be cut.
It has a stretcher and a heel,
This stretcher stretches a part of each cord, forms a narrow diameter part in this cord,
A device for cutting a tire sheet, in which the scissors can cut the cord at the small diameter portion. A step of supplying a sheet including a plurality of cords arranged in parallel to a cutting device including a stretcher and a scissors, and the stretcher having a main body;
The stretcher stretches a part of each cord and forms a narrow portion in the cord;
Cutting the cord at the small diameter portion to form a ply;
Obtaining a raw cover including the ply;
A method of manufacturing a tire, comprising: inserting the raw cover into a mold, and pressurizing and heating in the mold.   The tire manufacturing method according to claim 2, wherein the ratio of the area of the cut surface of the cord to the cross-sectional area of the cord is 25% or less.

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