JP5113730B2 - Exhaust groove forming method and exhaust groove forming apparatus - Google Patents

Description

  The present invention relates to an exhaust groove forming method and an exhaust groove forming apparatus for forming an exhaust groove on one surface of an unvulcanized rubber strip from a rubber extruder.

  In recent years, in pneumatic tires, a long strip of rubber strip extruded by a small rubber extruder is spirally wound in the circumferential direction on a molding drum, thereby forming a strip wound body close to a desired cross-sectional shape. A so-called strip wind method has been proposed in which a rubber member for a tire is formed directly on a molding drum. However, in the case of this strip wind method, gaps are formed between the wound rubber strips or between the rubber strips and the molding drum, so that after the vulcanization molding, air remains in the gaps, and tires such as uniformity There are problems such as incurring quality degradation.

  Accordingly, in the following Patent Document 1, the present applicant forms an exhaust groove on one surface of the rubber strip by pressing a molding roller having a groove-forming rib protruding on the outer peripheral surface against the rubber strip, thereby preventing air remaining. An exhaust groove forming method and apparatus are proposed.

JP 2006-051711 A

  On the other hand, in the strip wind method, in order to synchronize with the formation process time of other tire members, the conveyance speed of the rubber strip between the rubber extruder and the forming drum is switched between a high speed and a low speed. . However, as a result of the inventor's research, when the mold roller is pressed against the rubber strip with a constant pressing force, for example, at low speed operation, the depth of the exhaust groove formed becomes excessive and the rubber strip is cut. It has been found that the exhaust depth is too small and the exhaust effect is not sufficiently exhibited during high-speed operation, leading to problems such as the occurrence of residual air.

  Therefore, the present invention includes a pressing force switching step for switching the pressing force of the molding roller to a large value when the rubber strip conveyance speed is high and a small pressing force when the conveyance speed is low in the roller pressing process. The exhaust groove forming method that can stably form the exhaust groove even in high-speed operation and low-speed operation, and that can prevent a decrease in productivity due to a rubber strip breakage and a decrease in tire quality due to remaining air, and An object is to provide an exhaust groove forming apparatus.

In order to achieve the above-mentioned object, the invention of claim 1 of the present application is characterized in that the length is formed on one surface of an unvulcanized rubber strip having a long strip shape which is continuously formed by a rubber extruder and conveyed in the length direction. An exhaust groove forming method for forming an exhaust groove extending in a direction intersecting with a direction,
A roller pressing step for forming the exhaust groove by pressing a molding roller, which is rotatably supported and has a groove forming rib for forming an exhaust groove extending in a direction crossing the circumferential direction on the outer peripheral surface, against the rubber strip. As well as
The roller pressing step is a pressing force switching step for switching the pressing force to a small value when the conveying speed of the rubber strip is high and the pressing force of the molding roller to the rubber strip is large and when the conveying speed is a low speed. It is characterized by having.

Further, the invention of claim 2 is an exhaust groove extending in a direction intersecting with the length direction on one surface of an unvulcanized rubber strip having a long belt shape which is continuously formed by a rubber extruder and conveyed in the length direction. An exhaust groove forming apparatus for forming
A molding roller that is pivotally supported rotatably and has a groove-forming rib for projecting an exhaust groove extending in a direction crossing the circumferential direction on the outer peripheral surface;
A pressing means for forming the exhaust groove by pressing the molding roller against the rubber strip;
The pressing means includes a pressing force switching tool for switching the pressing force to a large value when the conveying speed of the rubber strip is high, and switching the pressing force to a small value when the conveying speed is low. It is characterized by including.

  According to a third aspect of the present invention, the pressing means includes a spring urging tool that urges the mold roller forward toward the rubber strip, and the pressing force switching tool moves the spring urging tool forward and backward. It is characterized in that the pressing force can be increased by changing the position to the front, and the pressing force can be changed to small by changing the position to the rear.

  According to a fourth aspect of the present invention, the pressing force switching tool includes a cylinder, and the spring biasing tool is moved back and forth by expansion and contraction of a rod of the cylinder.

  As described above, in the method invention of claim 1, a pressing force switching step is provided in the roller pressing step of pressing the mold roller against the rubber strip. In the device invention of claim 2, a pressing force switching tool is provided in the pressing means for pressing the mold roller against the rubber strip. Accordingly, the pressing force of the mold roller can be increased during high-speed operation, and the pressing force can be freely switched during low-speed operation. As a result, the exhaust groove can be stably formed even in high-speed operation and low-speed operation, and it is possible to prevent a decrease in productivity due to a rubber strip breakage and a decrease in tire quality due to remaining air.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view conceptually showing a case where an exhaust groove forming apparatus 1 for carrying out the exhaust groove forming method of the present invention is incorporated in a strip manufacturing / conveying apparatus 2 for forming a rubber strip and transporting it to a forming drum. FIG.

  1 and 2, a strip manufacturing / conveying device (hereinafter referred to as manufacturing / conveying device) 2 includes a rubber extruder 3 that continuously forms a long strip of unvulcanized rubber strip G, and the rubber extruder. 3 and a conveying conveyor 4 that receives the rubber strip G from 3 at the receiving position P1 and conveys it to the forming drum D. Then, the exhaust groove forming device 1 is disposed at the receiving position P1, and as shown in FIG. 6, a plurality of exhaust grooves 14 extending in the direction crossing the length direction are formed on one surface of the rubber strip G.

  The rubber extruder 3 is a so-called roller head rubber extruder, which is a rubber extruder main body 5 that continuously discharges rubber from a discharge port 5A and preforms the rubber from the discharge port 5A. And a roller head 6 having upper and lower calendar rolls 6U and 6L for forming a rubber strip G having a predetermined cross-sectional shape.

  The conveyor 4 includes a non-extendable conveyor tape 31 guided by a plurality of guide rollers 30 so as to be capable of circular movement, and the rubber strip G is adhered to and held on one surface thereof to thereby hold the rubber strip G. It can be conveyed from the receiving position P1 to the feeding position P2 to the forming drum D. For the “holding”, the rubber adhesiveness of the unvulcanized rubber is used. Therefore, as the transport tape 31, a non-stretchable reinforcing core material made of organic fibers and coated with a surface layer of a polyester resin excellent in adhesiveness to unvulcanized rubber is suitably employed. The

  The conveyor 4 includes an outward accumulator means 8 for temporarily storing a rubber strip G continuously received at the receiving position P1 between the receiving position P1 and the sending position P2, and a rubber strip G. And a return accumulator means 9 for temporarily storing only the transporting tape 31 after having been fed out. A continuous operation driving roller 10 is provided on the upstream side of the outward accumulator means 8 to draw out the transport tape 31 stored in the return accumulator means 9. Further, on the downstream side of the forward path accumulator means 8, an intermittently driven driving roller for intermittently pulling out the transport tape 31 with a rubber strip stored in the forward path accumulator means 8 in synchronization with the forming drum D. 11 is arranged.

  Each of the accumulator means 8 and 9 is supported by a plurality of rotatable upper guide rollers 30U arranged in a horizontal row on a horizontal horizontal fixed frame 12 and freely movable up and down below the horizontal fixed frame 12. The horizontal elevating frame 13 is provided with a plurality of rotatable lower guide rollers 30L arranged in a horizontal row. The transport tape 31 is wound in a zigzag shape while alternately turning back between the upper guide roller 30U and the lower guide roller 30L facing each other in the vertical direction. At this time, as shown in FIG. 5, the transport tape 31 is wound between the guide rollers 30 </ b> U and 30 </ b> L with a twist J obtained by twisting one surface S <b> 1 and the other surface S <b> 2 by 180 °. As a result, the transport tape 31 can come into contact with the guide rollers 30U and 30L only by the other surface S2 that does not hold the rubber strip G by adhesion, and can be prevented from stably rotating and deformation of the rubber strip G.

  Here, when the rubber strip G is transported while being adhered to the non-extensible transport tape 31, it is possible to prevent the rubber strip G from being cut or deformed during the transport and to form a raw rubber product efficiently and stably. Has the advantage of being able to. However, since the rubber strip G is stuck and restrained by the conveyance tape 31 during the conveyance, the shrinkage of the rubber strip G after the extrusion occurs after the raw rubber product is formed. As a result, raw rubber products tend to be gradually deformed by rubber contraction, leading to dimensional changes and shape changes.

  Therefore, in this example, a shrink region Y is formed between the rubber extruder 3 and the transport conveyor 4 so that the rubber strip G is not restrained and is loosely suspended in a U shape. In the shrink region Y, the rubber strip G is free without being constrained, so that the rubber can freely contract. Therefore, prior to the conveyance by the conveyance tape 31, it becomes possible to freely give the rubber strip G the maximum rubber shrinkage required by the rubber strip G, to suppress the rubber shrinkage after the conveyance, and to change the dimensions of the raw rubber product. And shape change can be suppressed.

  Next, in the manufacturing / conveying device 2 of the present embodiment, the exhaust groove forming device 1 is disposed at the receiving position P1. In the receiving position P1, a guide roller 30 for guiding the transport tape 31, in this example, the driving roller 10, is provided, and the transport tape 31 is driven at a predetermined transport speed V.

  Further, as shown in FIG. 3, the exhaust groove forming apparatus 1 includes a mold roller 15 that is rotatably supported, and pressing means 16 that forms the exhaust groove 14 by pressing the mold roller 15 against the rubber strip G. The pressing means 16 increases the pressing force of the molding roller 15 against the rubber strip G when the conveying speed V of the rubber strip G is high V1, and the conveying speed V is low V2. In some cases (shown in FIG. 4), the pressing force switching tool 17 is configured to switch the pressing force to a small value.

  Specifically, the mold roller 15 includes a cylindrical roller body 19 pivotally supported by a roller holder 18 and an exhaust gas projecting from the outer peripheral surface of the roller body 19 and extending in a direction intersecting with the circumferential direction. And a groove-forming rib 20 for groove formation. As shown in FIG. 6A, the angle θ with respect to the circumferential direction of the groove forming rib 20, that is, the angle θ with respect to the length direction of the rubber strip G of the exhaust groove 14 formed in the rubber strip G is not particularly restricted. If the angle θ is too small, the length of the exhaust passage becomes excessive and the exhaust efficiency is impaired, and air may remain in the exhaust passage. However, if the angle θ is too large, the strength in the length direction is reduced, and the rubber strip G may be broken due to the tension force when it is wound around the forming drum D. Therefore, the lower limit of the angle θ is preferably 20 ° or more, more preferably 30 ° or more, and the upper limit is preferably 80 ° or less, more preferably 70 ° or less, and further preferably 60 ° or less.

  In order to form the exhaust groove 14 by pressing the groove-forming rib 20, it is preferable that the cross-sectional shape of the groove-forming rib 20 is a rectangular shape as shown in FIG. It is preferable that Further, from the viewpoint of the exhaust effect and the strength of the rubber strip G, the height h of the groove forming rib 20 is preferably 1.0 mm or more and the width w is preferably in the range of 1.0 to 1.5 mm. The outer peripheral surface of the roller body 19 does not need to be in contact with the rubber strip G.

  The pressing means 16 includes a spring biasing tool 21 that biases the mold roller 15 forward toward the rubber strip G, and a pressing force switching tool 17 that can change the position of the spring biasing tool 21 back and forth. Have. The spring biasing tool 21 has, for example, two guide shafts 23 rising forward from the base 22, and the guide shafts 23 pass through the sliding holes 18 </ b> A provided in the roller holder 18, thereby Guide 18 forward and backward. The guide shaft 23 is provided with a spring piece 24, for example, a call spring, for urging the roller holder 18 forward.

  Further, in this example, the pressing force switching tool 17 is a cylinder 25 including a guide shaft 25A. The rod 25B is supported by a frame or the like with the rod 25B facing forward, and the spring 25 is provided at the front end of the rod 25B. A base 22 of the biasing tool 21 is attached. Accordingly, the pressing force switching tool 17 fills the rod 25B until the stopper 26 provided at the rear end of the guide shaft 25A comes into contact with the rear end of the cylinder 25 by filling the working air from the port pa. The spring biasing tool 21 can be repositioned to the forward movement position Q1. The advance position Q1 can be freely set by adjusting the position of the stopper 26, for example. Further, the pressing force switching tool 17 can reduce the rod 25B by filling the working air from the port pb until the front end of the cylinder 25 and the spring urging tool 21 come into contact with each other. Can be repositioned from the forward position Q1 to the reverse position Q2 (shown in FIG. 4).

Therefore, when the position change amount between the forward position Q1 and the reverse position Q2 is L, and the spring constant of the whole spring urging tool 21 is K, the pressing force F of the molding roller 15 is changed by the position change. It can be increased or decreased by ΔF.
ΔF = L × K

  The forward biasing force of the rod 25B by the working air is sufficiently larger than the pressing force F of the mold roller 15, and therefore the forward movement position Q1 is not changed by the reaction force due to the pressing. The operation air can be switched to the ports pa and Pb by, for example, an electromagnetic valve. The position of the spring urging tool 21 can be changed only by turning on / off the working air to the port pa.

  Further, the manufacturing / conveying device 2 of this embodiment includes control means for controlling the conveying conveyor 4, the pressing force switching tool 17, and the rubber extruder 3. This control means switches the electromagnetic valve when the transport speed V of the transport tape 31 is a high speed V1, and changes the position of the spring biasing tool 21 from the reverse position Q2 to the forward position Q1 by the pressing force switching tool 17. As a result, the pressing force F of the molding roller 15 can be switched from small to large. At the same time, the control device can switch the operating speed of the rubber extruder 3, that is, the extrusion speed of the rubber strip G, from the low speed V2 to the high speed V1. Conversely, when the transport speed V of the transport tape 31 is the low speed V2, the control means switches the electromagnetic valve, and the pressing force switching tool 17 moves the spring biasing tool 21 from the forward position Q1 to the reverse position Q2. Let me change. As a result, the pressing force F of the molding roller 15 can be switched from large to small. Further, the control device switches the operation speed of the rubber extruder 3, that is, the extrusion speed of the rubber strip G from high speed to low speed.

  The exhaust groove forming method using the exhaust groove forming apparatus 1 includes a roller pressing step (FIG. 6A) for forming the exhaust groove 14 by pressing the mold roller 15 against the rubber strip G. In this roller pressing step, a pressing force switching step (FIGS. 3 and 4) is performed using the pressing force switching tool 17, and when the conveying speed V is a high speed V1, the pressing force F of the molding roller 15 is increased. When the transport speed V is the low speed V1, the pressing force F is switched to a small value.

  Thus, the exhaust groove forming apparatus 1 and the exhaust groove forming method are such that the pressing force F of the molding roller 15 is large when the conveying speed V of the rubber strip G is high V1, and the pressing force when the conveying speed V of the rubber strip G is low. Since F is switched to a small value, the exhaust groove 14 can be accurately and stably formed in the rubber strip G even at high speeds and low speeds. Therefore, it is possible to effectively prevent a decrease in productivity due to the rubber strip being cut and a decrease in tire quality due to remaining air.

  In the manufacturing / conveying device 2, the rubber strip G is adhered and held on the conveying tape 31 by the pressing force F of the molding roller 15. The rubber strip G tends to peel from the transport tape 31. On the contrary, in the case of the low speed V2, the rubber strip G tends to be wound around the shaping roller 15. However, in the present invention, since the pressing force F of the molding roller 15 is switched between large and small according to the high speed / low speed, the peeling of the rubber strip G from the conveying tape 31 and the winding around the molding roller 15 are prevented at the same time. be able to.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

In order to confirm the effect of the present invention, a rubber strip manufacturing / conveying device having a structure shown in FIG. 1 was used, and a rubber strip G having a drain groove formed on one surface was wound around a molding drum D to form a tread rubber. And the following problem when this tread rubber was formed was compared.
(1) When the rubber strip G is transported by the transport tape 31 from the receiving position P1 to the delivery position P2, the rate of occurrence of separation of the rubber strip G from the transport tape 31 is defined as the number of tread rubber formations 100. Measurement was performed for each piece (when one tread rubber is formed, peeling may occur several times).
(2) When the rubber strip G is adhered to the transport tape 31 using the molding roller 15, the rate at which the rubber strip does not peel off at the delivery position P2 and returns to the accumulator means 9 side is defined as the number of tread rubber formations. Measurements were made on 100 pieces. (When one tread rubber is formed, winding may occur a plurality of times.)
(3) The rate of occurrence of defective air remaining products, in which the drainage groove was poorly formed and air residue was generated and the tread rubber became defective, was measured for 100 tread rubber formations.
(4) With respect to the number of tread rubber formations of 100, the drainage groove is poorly formed, the strength of the rubber strip G is reduced, and the rubber strip G is not peeled off from the transport tape 31 and is cut. It was measured.
(When one tread rubber is formed, the rubber strip may be cut several times.)

  The molding roller 15 has a roller body 19 with a diameter of 80 mm, a width of 40 mm, the number of groove-forming ribs 20 formed (equally spaced in the circumferential direction), a forming angle θ of 45 °, and a rib height h of 1. 5 mm and rib width w is 1.0 mm. Further, the spring constant K of the whole spring urging tool 21 is 75 g / mm, and the repositioning amount L between the forward position Q1 and the backward position Q2 is 5 mm. The conveyance speed of the rubber strip G at high speed is 1400 mm / sec, and the conveyance speed at low speed is 50 mm / sec.

It is a side view which shows notionally the case where the exhaust groove formation apparatus for enforcing the exhaust groove formation method of this invention is integrated in the strip manufacture and conveyance apparatus which forms a rubber strip and conveys to a forming drum. It is a side view which expands and shows a part. It is a side view which shows the exhaust groove formation apparatus in the position change state ahead. It is a side view which shows the exhaust groove formation apparatus in the position change state back. It is a perspective view which shows the twist of a conveyance tape. (A) is a perspective view which shows the roller pressing process by a shaping | molding roller, (B) is a fragmentary sectional view which shows the cross-sectional shape of a groove formation rib.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust groove forming apparatus 3 Rubber extruder 14 Exhaust groove 15 Molding roller 16 Pressing means 17 Pressing force switching tool 20 Groove forming rib 21 Spring biasing tool 25 Cylinder 25A Rod G Rubber strip V Conveying speed

Claims (4)

An exhaust groove forming method for forming an exhaust groove extending in a direction crossing the length direction on one surface of an unvulcanized rubber strip having a long strip shape that is continuously formed by a rubber extruder and conveyed in the length direction. There,
A roller pressing step for forming the exhaust groove by pressing a molding roller, which is rotatably supported and has a groove forming rib for forming an exhaust groove extending in a direction crossing the circumferential direction on the outer peripheral surface, against the rubber strip. As well as
The roller pressing step is a pressing force switching step for switching the pressing force to a small value when the conveying speed of the rubber strip is high and the pressing force of the molding roller to the rubber strip is large and when the conveying speed is a low speed. An exhaust groove forming method characterized by comprising: An exhaust groove forming device for forming an exhaust groove extending in a direction crossing the length direction on one surface of a long strip-like unvulcanized rubber strip formed continuously by a rubber extruder and conveyed in the length direction. There,
A molding roller that is pivotally supported rotatably and has a groove-forming rib for projecting an exhaust groove extending in a direction crossing the circumferential direction on the outer peripheral surface;
A pressing means for forming the exhaust groove by pressing the molding roller against the rubber strip;
The pressing means includes a pressing force switching tool for switching the pressing force to a large value when the conveying speed of the rubber strip is high, and switching the pressing force to a small value when the conveying speed is low. An exhaust groove forming apparatus comprising:   The pressing means has a spring urging tool for urging the mold roller forward toward the rubber strip, and the pressing force switching tool can change the position of the spring urging tool forward and backward. 3. The exhaust groove forming apparatus according to claim 2, wherein the pressing force is switched to a large value by changing the position of the gas and the pressing force is switched to a small value by changing the position to the rear.   4. The exhaust groove forming apparatus according to claim 3, wherein the pressing force switching tool includes a cylinder, and the spring biasing tool is moved back and forth by expansion and contraction of a rod of the cylinder.

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