JP2018062109A - Method for producing rubber strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a rubber strip capable of suppressing leakage of unvulcanized rubber from a discharge port of a gear pump after rotation of a gear is stopped.SOLUTION: The manufacturing method alternately includes a supplying step for continuously supplying a secondary strip S2 and a stopping step for stopping the supply of the secondary strip S2. The supplying step includes a step of rotating a calender roll 3 while normally rotating a gear 22 of a gear pump 2. The stopping step includes: a first step of stopping rotation of the calender roll 3; and a second step P22 of stopping normal rotation of the gear 22 of the gear pump 2 while stopping after rotating the gear 22 in the reverse direction so that discharge pressure of the gear pump 2 decreases without breaking a primary strip S1 extending between the gear pump 2 and the calender roll.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for intermittently producing a rubber strip using a rubber extrusion device.

  Conventionally, as a method of manufacturing a rubber strip using a rubber extrusion device, for example, Patent Document 1 discloses a technique for turning off rotation of a calendar roll prior to turning off rotation of a gear pump.

Japanese Patent No. 5351931

  In the technique described in Patent Document 1, the primary strip pushed out from the gear pump is slackened, and the primary strip is prevented from being broken by shrink.

  However, after the rotation of the gear stops, the pressure of the unvulcanized rubber in the gear pump increases and the unvulcanized rubber may leak out from the discharge port of the gear pump. If the unvulcanized rubber leaks out after the rotation of the gear is stopped in this manner, the shape of the primary strip in the next rubber strip supply process may be affected.

  The present invention has been devised in view of the actual situation as described above, and provides a rubber strip manufacturing method capable of suppressing leakage of unvulcanized rubber from the discharge port of the gear pump after the rotation of the gear is stopped. Is the main purpose.

  The present invention provides a rubber extrusion apparatus comprising a gear pump including a pair of gears for extruding plasticized unvulcanized rubber as a primary strip, and a pair of calender rolls for rolling the primary strip into a secondary strip. A method for intermittently manufacturing a strip, comprising alternately supplying a secondary strip continuously and a stopping step of stopping the supply of the secondary strip, the supplying step including the gear pump A step of rotating the pair of calendar rolls while rotating the gears in a normal direction, and the stopping step includes a first step of stopping the rotation of the pair of calendar rolls, and then the forward rotation of the gears of the gear pump. And the primary strip extending between the gear pump and the pair of calender rolls is broken. As the discharge pressure of the gear pump is lowered without having, characterized in that it comprises a second step of stopping after reversed the gear.

  In the rubber strip manufacturing method according to the present invention, it is preferable that the second step reverses the gear so that the discharge pressure is 1 to 2 MPa.

  In the rubber strip manufacturing method according to the present invention, the reverse rotation speed of the gear is preferably 0.1 rpm to 1.0 rpm.

  In the rubber strip manufacturing method according to the present invention, it is desirable that the reverse rotation time of the gear is 0.5 to 4.0 seconds.

  In the rubber strip manufacturing method according to the present invention, it is preferable that the supplying step includes a step of starting rotation of the calendar roll before starting forward rotation of the gear.

  The present invention alternately includes a supply process for continuously supplying the secondary strip and a stop process for stopping the supply of the secondary strip. The supplying step includes a step of rotating the pair of calendar rolls while normally rotating the gear pump gear. The stopping step includes a first step of stopping the rotation of the pair of calendar rolls, and then a second step of stopping the forward rotation of the gear pump and then stopping the gear pump after reversing the gear. By the second step, the discharge pressure of the gear pump is reduced, and leakage of unvulcanized rubber from the discharge port is suppressed. Further, since the gear is reversed and then stopped so that the primary strip extending between the gear pump and the pair of calender rolls is not broken, breakage of the primary strip due to shrinkage can be suppressed.

It is sectional drawing of the rubber extrusion apparatus used for the manufacturing method of the rubber strip of one Embodiment of this invention. It is sectional drawing which shows the operation | movement in the supply process of the rubber extrusion apparatus of FIG. It is a cross section which shows the operation | movement in the stop process (1st process) of the rubber extrusion apparatus of FIG. It is a cross section which shows the operation | movement in the stop process (2nd process) of the rubber extrusion apparatus of FIG. It is a cross section which shows the operation | movement in the stop process (2nd process following FIG. 4) of the rubber extrusion apparatus of FIG. 6 is a graph showing the rotation speed of the calendar roll, the rotation speed of the gear, and the pressure at the inlet of the gear pump in the supply process of FIG. 2 and the stop process of FIGS.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a rubber extrusion device 1 used in a method for producing a rubber strip according to an embodiment of the present invention. The rubber extruding device 1 includes a gear pump 2 that extrudes the plasticized unvulcanized rubber G as a primary strip S1, and a pair of calendar rolls 3 that roll the primary strip S1 into a secondary strip S2.

  The gear pump 2 includes a casing 21 and a plurality of gears 22 that mesh with each other in the casing 21. The casing 21 is provided with a discharge port 23 for extruding the unvulcanized rubber G into a predetermined shape.

  The gear 22 is driven by a motor (not shown) or the like, and is configured to be rotatable in the forward rotation direction and the reverse rotation direction. The forward rotation direction indicated by the arrow R1 is a rotation direction in which the unvulcanized rubber G filled in the casing 21 is pushed out from the discharge port 23 toward the calendar roll 3 downstream. The reverse rotation direction indicated by the arrow R <b> 2 is a rotation direction opposite to the normal rotation direction, and is a rotation direction in which the unvulcanized rubber G in the vicinity of the discharge port 23 is drawn upstream of the gear pump 2.

  The rotation of the gear 22 is controlled by the control means 9. The control means 9 controls the rotational direction and rotational speed of the gear 22 by adjusting the voltage applied to the motor.

  In the rubber extrusion device 1 of this embodiment, the gear pump 2 is provided on the downstream side of the extruder body 5. The extruder body 5 includes a cylindrical casing 51, a screw shaft 52 accommodated in the casing 51, and an inlet 53 for introducing unvulcanized rubber G into the casing 51. ing.

  The screw shaft 52 includes a shaft main body 52a and a spiral blade 52b protruding from the shaft main body 52a to the outside in the radial direction of the screw shaft 52. The spiral blade 52 b is continuously formed in the circumferential direction while being displaced in the axial direction of the screw shaft 52. The spiral blade 52 b pushes the unvulcanized rubber G in the casing 51 while kneading it toward the discharge port 23. At this time, the unvulcanized rubber G generates heat and is plasticized.

  In the rubber extrusion device 1 of the present embodiment, the relative distance between the discharge port 23 of the gear pump 2 and the calendar roll 3 is constant.

  A recess corresponding to the cross-sectional shape of the secondary strip S <b> 2 is formed on the outer peripheral surface of at least one calendar roll 3. By rolling the primary strip S1 with the calendar roll 3, the secondary strip S2 having a desired cross-sectional shape is accurately manufactured.

  The rotation of the screw shaft 52 and the rotation of the calendar roll 3 are controlled by the control means 9. The control means 9 controls the gear 22, the screw shaft 52, and the calendar roll 3 in synchronization.

  The rubber extrusion device 1 is used for manufacturing a tire, for example. In this case, the secondary strip S2 is spirally wound around the surface of a cylindrical former (not shown) to form tire tread rubber or sidewall rubber. The tire is composed of various members such as a carcass and a belt in addition to the tread rubber and the sidewall rubber. In order to sequentially wind each member around the former, it is necessary to manufacture the rubber strip intermittently.

  That is, the rubber strip manufacturing method of the present invention alternately includes a supply process P1 for continuously supplying the secondary strip to a former or the like and a stop process P2 for stopping the supply of the secondary strip.

  FIG. 2 shows the rubber extrusion device 1 in the supply step P1. The supply process P1 includes a process of rotating the pair of calendar rolls 3 in the direction of the arrow R3 while rotating the gear 22 of the gear pump 2 in the normal direction.

  3 to 5 show the rubber extrusion device 1 in the stopping process P2. The stop process P2 includes a first process P21 shown in FIG. 3 and second processes P22 and P23 shown in FIGS.

  FIG. 6 shows the rotation speed V3 of the calender roll 3 in the supply process P1 and the stop process P2, the rotation speed V22 of the gear 22 and the pressure PG at the inlet of the gear pump 2 aligned vertically with the horizontal axis aligned. Show.

  As shown in FIGS. 2 and 6, in the supply process P1, the control means 9 causes the gear 22 to rotate forward so that the unvulcanized rubber G filled in the casing 21 becomes the primary strip S1 from the discharge port 23. Extruded and supplied to the calendar roll 3.

  As shown in FIGS. 3 and 6, in the first process P <b> 21 of the stop process P <b> 2, the control unit 9 stops the rotation of the pair of calendar rolls 3. In the first step P21, it is desirable that the forward rotation of the gear 22 is continued while decelerating. Thereby, since the primary strip S1 is continuously extruded from the discharge outlet 23, it can suppress that the primary strip S1 slacks slightly and is fractured | ruptured by shrink.

  As shown in FIGS. 4 and 6, in the second step P <b> 22 subsequent to the first step P <b> 21, the control means 9 stops the forward rotation of the gear 22 of the gear pump 2 and further reverses the gear 22. Due to the reverse rotation of the gear 22, a part of the unvulcanized rubber G moves from the vicinity of the discharge port 23 toward the inlet side of the gear pump 2, and the pressure PG increases. Along with this, the pressure of the unvulcanized rubber G on the downstream side of the gear 22 in the casing 21 decreases. Accordingly, the discharge pressure of the gear pump 2 is reduced, and leakage of the unvulcanized rubber G from the discharge port 23 can be suppressed.

  Thereafter, as shown in FIGS. 5 and 6, in the second step P23, the control means 9 reverses the gear 22 so that the primary strip S1 extending between the gear pump 2 and the pair of calendar rolls 3 is not broken. Stop. Thereby, the discharge pressure of the gear pump 2 is maintained at an appropriate value, and breakage due to shrinkage of the primary strip S1 can be suppressed.

  In the second step P22, the control means 9 desirably reverses the gear 22 so that the discharge pressure of the gear pump 2 becomes 1 to 2 MPa. The discharge pressure of the gear pump 2 here is the discharge pressure of the gear pump 2 after 2 seconds have elapsed since the reverse rotation of the gear 22 was stopped in the second step P22. When the discharge pressure of the gear pump 2 is less than 1 MPa, the primary strip S1 may be broken by shrink. On the other hand, when the discharge pressure of the gear pump 2 exceeds 2 MPa, the unvulcanized rubber G may leak from the discharge port 23.

  The reverse rotation speed of the gear 22 is preferably 0.1 rpm to 1.0 rpm. When the reverse rotation speed of the gear 22 is less than 0.1 rpm, the discharge pressure of the gear pump 2 is not sufficiently reduced, and the unvulcanized rubber G may leak from the discharge port 23. On the other hand, when the reverse rotation speed of the gear 22 exceeds 1.0 rpm, the discharge pressure of the gear pump 2 is excessively reduced, and the primary strip S1 may be broken by shrink.

  The reverse rotation time of the gear 22 is preferably 0.5 to 4.0 seconds. When the reverse rotation time of the gear 22 is less than 0.5, the discharge pressure of the gear pump 2 is not sufficiently reduced, and the unvulcanized rubber G may leak from the discharge port 23. On the other hand, when the reverse rotation time of the gear 22 exceeds 4.0 seconds, the discharge pressure of the gear pump 2 is excessively reduced, and the primary strip S1 may be broken by shrink.

  As already described, the rubber strip manufacturing method of the present invention alternately includes the supply process P1 for continuously supplying the secondary strip and the stop process P2 for stopping the supply of the secondary strip. Therefore, when the second process P23 included in the stop process P2 is completed, one manufacturing cycle is completed, and the supply process P1 shown in FIG. 1 is started in the next manufacturing cycle.

  As shown in FIG. 6, the supply process P <b> 1 includes a rotation start process P <b> 11 that starts the rotation of the gear 22 and the calendar roll 3. In the rotation start process P <b> 11, it is desirable that the control unit 9 starts the rotation of the calendar roll 3 before the forward rotation of the gear 22 is started. Sag of the primary strip S1 in the supply process P1 is suppressed, and appropriate tension is applied to the primary strip S1. Thus, the primary strip S1 is rolled into a desired shape by the calendar roll 3.

  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.

  Unvulcanized rubber was extruded using the rubber extrusion apparatus shown in FIG. 1, and the state of the primary strip was evaluated. In addition, the discharge pressure was measured immediately after the reverse rotation of the gear stopped and after 2 seconds.

<State of primary strip>
The state of the primary strip 30 seconds after the reverse rotation of the gear was stopped was evaluated visually by the operator. The result is expressed as a score of Example 2 as 100, and the larger the value, the less the unvulcanized rubber leaked from the discharge port of the gear pump.

  As is apparent from Table 1, as a result of the test, the rubber strip manufacturing method of the example has less leakage of unvulcanized rubber from the discharge port of the gear pump and the state of the primary strip is better than the comparative example. It was confirmed that.

DESCRIPTION OF SYMBOLS 1 Rubber extrusion apparatus 2 Gear pump 3 Calendar roll 22 Gear 23 Discharge port G Unvulcanized rubber P1 Supply process P2 Stop process P21 1st process P22 2nd process P23 2nd process S1: Primary strip S2: Secondary strip

Claims (5)

Intermittent rubber strips using a rubber extrusion device comprising a gear pump having a pair of gears for extruding plasticized unvulcanized rubber as a primary strip and a pair of calender rolls for rolling the primary strip into a secondary strip A method of manufacturing,
Alternately including a supply step of continuously supplying the secondary strip and a stop step of stopping the supply of the secondary strip,
The supply step includes
Including rotating the pair of calender rolls while rotating the gear of the gear pump forward,
The stopping step includes
A first step of stopping rotation of the pair of calendar rolls;
Subsequently, the gear pump of the gear pump is stopped so that the forward rotation of the gear pump is stopped, and the discharge pressure of the gear pump is reduced without breaking the primary strip extending between the gear pump and the pair of calender rolls. A method of manufacturing a rubber strip, comprising: a second step of stopping after reverse rotation.   The rubber strip manufacturing method according to claim 1, wherein the second step reverses the gear so that the discharge pressure becomes 1 to 2 MPa.   The method for producing a rubber strip according to claim 1 or 2, wherein a reverse rotation speed of the gear is 0.1 rpm to 1.0 rpm.   The method for producing a rubber strip according to any one of claims 1 to 3, wherein the reverse rotation time of the gear is 0.5 to 4.0 seconds.   The method of manufacturing a rubber strip according to any one of claims 1 to 4, wherein the supplying step includes a step of starting rotation of the calendar roll before starting forward rotation of the gear.

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