JP5574843B2 - Unvulcanized rubber extrusion apparatus and extrusion molding method - Google Patents

Description

  In this invention, an unvulcanized rubber material is fed to a gear pump at the tip of the extruder by a screw inside the extruder, the rubber material is quantitatively extruded from the gear pump, and a required cross-sectional shape is given. For example, the present invention relates to an extrusion molding apparatus and an extrusion molding method for forming a ribbon-like strip suitable for use in the production of raw tires, and in particular, the temperature of a rubber material fed to a gear pump is always appropriate. The present invention proposes a technique for preventing deterioration of the quality of an extruded rubber material.

Conventionally, as this type of extrusion molding apparatus, there are those described in Patent Documents 1 and 2.
In these extrusion molding apparatuses, an unvulcanized rubber material is wound around a molding core for producing a raw tire, such as a molding drum, a hard core, or a base tire, using a base provided at the tip in the extrusion direction. Therefore, it is extruded into a ribbon-like strip having a desired cross-sectional shape.

  By the way, the screw provided inside the extruder that forms a part of the extrusion molding apparatus is kneaded with an unvulcanized rubber material supplied into the extruder by being given a rotational driving force, and rubber. While raising the temperature of the material, it functions to feed the rubber material towards a gear pump located at the tip of the extruder.

JP 2000-79642 A JP 2009-113202 A

  However, when the screw of the extruder is always rotated at the same speed, depending on the material of the unvulcanized rubber material to be extruded, it may not be appropriate to heat the rubber material with the screw. As a result, there is a problem that the quality of a tire manufactured using a strip extruded from an extrusion molding apparatus is deteriorated.

  That is, when the temperature of the rubber material fed through the extrusion molding apparatus varies greatly over time due to the material of the rubber material, the amount of heat shrinkage of the extruded ribbon-like strip becomes longer in the longitudinal direction. As a result, it becomes difficult to maintain the shape of the molded strip, and as a result, the quality of the tire molded using such a strip may be affected. When the temperature of the rubber material rises significantly, a strip of unvulcanized rubber that has started the crosslinking reaction is extruded, and then wound on a drum to vulcanize the green tire to form part of the strip. May become excessively vulcanized, or if the temperature of the rubber material is significantly reduced, it may cause a decrease in the adhesiveness of the extruded strip to other tire components. That.

  The object of the present invention is to solve such problems of the prior art, and the object of the present invention is to bring unvulcanized rubber material fed through the apparatus within an appropriate temperature range. Extrusion molding of unvulcanized rubber that can effectively prevent degradation of the quality of the ribbon-like strips that are extruded and, for example, the quality of raw tires that are molded using this, It is to provide an apparatus and an extrusion method.

The unvulcanized rubber extrusion molding apparatus according to the present invention includes a gear pump for quantitatively extruding a rubber material fed from the extruder at a tip of an extruder having a screw therein, and a rubber material extruded from the gear pump. It is provided with a required cross-sectional shape, for example, a molding means such as a roller molding machine or a molding die, and is provided in an internal passage through which the rubber material flows between the screw of the extruder and the gear pump. , together with arranging the temperature sensor, from the temperature sensor, based on the temperature signal of the rubber material, Ri Na provided speed control means for varying the rotational driving speed of the screw of the extruder, the speed control means, said temperature The increase / decrease width of the rotational drive speed of the screw is changed according to the temperature gradient detected by the sensor .

The unvulcanized rubber extrusion molding method of the present invention is a method of feeding unvulcanized rubber material to a gear pump attached to the tip of the extruder with a screw inside the extruder, When forming by quantitative extrusion with a gear pump, the temperature sensor provided in the internal passage between the screw of the extruder and the gear pump detects the temperature of the rubber material flowing through the internal passage, and based on the detected temperature, The screw rotational speed of the extruder is increased / decreased to adjust the temperature of the rubber material fed to the gear pump, and the increase / decrease width of the rotational speed of the screw is changed according to the temperature gradient detected by the temperature sensor. .

  Preferably, when the rubber temperature detected by the temperature sensor exceeds a set upper limit value lower than the allowable upper limit value, the rotational drive speed of the screw of the extruder is decreased, and the rubber temperature is lower than the allowable lower limit value. Increase the rotational drive speed of the screw when it falls below the high set lower limit.

  According to the unvulcanized rubber extrusion molding apparatus or extrusion molding method of the present invention, the rotation of the screw of the extruder according to the temperature of the rubber material measured by the temperature sensor disposed in the internal passage between the screw and the gear pump. Since the drive speed can be changed, the rubber material fed to the gear pump can be always heated to a temperature within an appropriate range according to the material of the rubber material, based on the heating by the screw. For this reason, it is possible to effectively prevent deterioration of the quality of the green tire molded using the ribbon-shaped strip that is extruded.

  Here, in the unvulcanized rubber extrusion molding method, a set upper limit value lower than the allowable upper limit value and a set lower limit value higher than the allowable lower limit value of the temperature of the rubber material are determined in advance, and each of these set values When the rotational drive speed of the screw is increased or decreased when exceeding or below the value, the temperature of the rubber material fed to the gear pump is substantially between these allowable upper and lower limits. By controlling the rotational drive speed, for example, by making the entire rubber material to be extruded and molded sufficiently close to the reference appropriate temperature according to the material at each of the set upper limit value and the set lower limit value, the time passes. The non-uniform heat shrinkage of the rubber material can be further suppressed, and the ribbon-shaped strip can maintain the shape imparted by the extrusion molding sufficiently reliably.

  Also, here, when changing the increase / decrease width of the rotational speed of the screw according to the temperature gradient of the rubber material fed to the gear pump, the fluctuation range of the temperature of the rubber material can be further reduced, The temperature control responsiveness of the rubber material can be further increased.

It is sectional drawing which shows embodiment of the extrusion molding apparatus which concerns on this invention. It is a graph which shows the temperature control example in the extrusion molding method which concerns on this invention. It is the same graph as FIG. 2 which shows the other temperature control example.

Embodiments of the present invention will be described below with reference to the drawings.
An extrusion molding apparatus 1 shown in a sectional view in FIG. 1 includes an extruder 2, a gear pump 3 disposed at the tip of the extruder 2, a base 4a attached to the tip of the gear pump 3 as a molding means 4 here, and a base And a roller molding machine 4b disposed apart from 4a.

Here, the extruder 2 includes a hopper 2a for supplying the unvulcanized rubber member 5 into the extruder cylinder, and guides the rubber material 5 from the hopper 2a to the gear pump 3 inside. A passage 2b formed to extend in the left-right direction is provided, and a screw 2c extending along the passage 2b in the cylinder and contributing to kneading and feeding of the rubber material 5 is provided. Is.
The screw 2c is connected to a driving means (not shown), such as a motor, which applies a rotational driving force thereto.

  In addition, here, the gear pump 3 includes a pair of gears 3a that mesh with each other in a direction (vertical direction in the figure) perpendicular to the extending direction of the screw 2c, and is rotated at a predetermined speed. By passing the rubber material 5 fed from the screw 2c between the gears 3a, the rubber material 5 is quantitatively extruded to the base 4a side.

Here, the temperature sensor 6 is disposed in an internal passage between the screw 2c of the extruder 2 and the gear pump 3 through which the rubber material 5 passes, and the above-described screw 2c is based on a signal from the temperature sensor 6. Speed control means for controlling the drive means is provided.
As a control method by such speed control means, for example, the rotational drive speed of the screw 2c of the extruder 2 can be changed based on the graph illustrated in FIG.

That is, as shown in FIG. 2 (a), a set lower limit value T1 higher than the allowable lower limit value and a set upper limit value T2 lower than the allowable upper limit value are preset according to the material of the rubber material 5 to be extruded. Then, the extrusion of the rubber material 5 is started, and the temperature sensor 6 appropriately detects the temperature of the rubber material 5 at a required time interval or continuously, and the detected temperature gradually decreases to a lower limit of setting. When the value falls below the value T1, as shown in FIG. 2B, the rotational speed of the screw 2c is increased from R1 to R2.
As a result, the function of heating the rubber material 5 in the extruder 2 by the screw 2c is enhanced, and the temperature of the rubber material 5 fed to the gear pump 3 gradually increases.

When the detected temperature of the rubber material 5 exceeds the set upper limit value T2, the rotational speed of the screw 2c is reduced to R2 to reduce the heating function by the screw 2c, thereby feeding the gear pump 3 The temperature of the rubber material 5 is gradually reduced.
According to such a speed control method of the extruder screw 2c, the temperature of the rubber material 5 fed to the gear pump 3 is determined according to the material by the selection of the set lower limit value T1 and the set upper limit value T2. Can be easily adjusted so as to be maintained in the vicinity of the reference appropriate temperature Ts between the upper limit value and the allowable upper limit value, so that the heating to the rubber material 5 by the screw 2c is always appropriate, and extrusion molding is performed. It is possible to prevent the quality of the ribbon-like strip 5a and the like from being deteriorated.
As specific numerical values of the set lower limit value T1 and the set upper limit value T2, for example, the set lower limit value T1 can be set to 50 ° C., and the set upper limit value T2 can be set to 130 ° C.

Preferably, as shown in FIG. 3, in addition to the set lower limit value T1 ′ and the set upper limit value T2 ′, other set values T3 and T4 between them are provided, and the other set values T3 and T4 are used to The rotational speed of 2c is changed more finely.
According to this, the fluctuation range of the temperature of the rubber material 5 fed to the gear pump 3 can be further reduced, and the responsiveness of the temperature control can be enhanced.

In order to improve the temperature control responsiveness by the control means, the increase / decrease width of the rotational drive speed of the screw 2c can be changed according to the temperature gradient detected by the temperature sensor 6.
That is, for example, when the detected temperature suddenly rises or falls within a short period of time, the rotational drive speed of the screw 2c is greatly reduced or increased according to the temperature gradient. When the speed is increased or decreased, the rotational drive speed of the screw 2c is slightly decreased or increased.

By the way, the illustrated extrusion molding apparatus 1 is for molding the rubber material 5 extruded from the gear pump 3 into, for example, a ribbon-shaped strip 5a by the molding means 4 of the die 4a and the roller molding machine 4b.
Here, the base 4a forms its discharge port into a required inner contour cross-sectional shape such as a flat rectangle, a parallelogram, and a hexagon, and the roller molding machine 4b has a required surface contour shape. It can comprise with a pair of roller which has.
In the illustrated embodiment, the rubber material 5 is molded by both the base 4a and the roller molding machine 4b. However, the rubber material 5 can be molded by only one of them.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Extruder 2a Hopper 2b Passage 2c Screw 3 Gear pump 3a Gear 4 Molding means 4a Base 4b Roller molding machine 5 Rubber material 5a Ribbon-shaped strip 6 Temperature sensor T1, T1 'Setting lower limit T2, T2' Setting upper limit T3, T4 Other set values Ts Reference appropriate temperature

Claims (3)

A gear pump for quantitatively extruding the rubber material fed from the extruder and a molding means for giving the required cross-sectional shape to the rubber material extruded from the gear pump are attached to the tip of an extruder having a screw inside. An unvulcanized rubber extrusion molding apparatus comprising:
A temperature sensor is disposed in the internal passage through which the rubber material flows between the screw of the extruder and the gear pump, and the rotational drive speed of the screw of the extruder is determined based on the temperature signal of the rubber material from the temperature sensor. Ri Na provided speed control means for changing,
The speed control means is an unvulcanized rubber extrusion apparatus that changes the increase / decrease width of the rotational drive speed of the screw according to the temperature gradient detected by the temperature sensor . When unvulcanized rubber material is fed to a gear pump attached to the tip of the extruder by a screw inside the extruder, and the rubber material is quantitatively extruded by the gear pump and molded, The temperature sensor provided in the internal passage between the gear pump detects the temperature of the rubber material flowing in the internal passage, and based on the detected temperature, the rotational drive speed of the screw of the extruder is increased or decreased, adjust the temperature of the rubber material fed,
A method for extruding unvulcanized rubber, wherein the increase / decrease width of the rotational drive speed of the screw is changed according to the temperature gradient detected by the temperature sensor .   When the rubber temperature detected by the temperature sensor exceeds a set upper limit value lower than the allowable upper limit value, the rotational drive speed of the screw of the extruder is slowed down, and the rubber temperature has a set lower limit value higher than the allowable lower limit value. 3. The method for extruding unvulcanized rubber according to claim 2, wherein when it falls below, the rotational drive speed of the screw is increased.

Images