JP2016215414A - Rubber extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber extruder capable of suppressing shrinkage of an extruded rubber extruded object in an extrusion direction in a short time despite a simple configuration.SOLUTION: A rectifying body 8 extending from a prescribed position, at which a protrusion amount a in a front direction from a front end face of an extrusion port 6 is 10 mm or less, toward a cylinder 2 is installed at least inside an extrusion flow passage 7 which is formed on a die 5, and rubber extruded by a screw is allowed to pass through gaps t1, t2 in a thickness direction of the extrusion flow passage 7 and the rectifying body 8 and gaps w, w in a width direction of the extrusion flow passage 7 and the rectifying body 8, and the rubber is extruded from the extrusion port 6, by which portions contacting an inner surface of the extrusion flow passage 7 of the rubber and the surface of the rectifying body 8 show behavior of extending in an extrusion direction after extrusion, and the extending behavior suppresses shrinkage at the central part in cross section of a rubber extruded object R which is about to shrink .SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rubber extrusion device, and more particularly to a rubber extrusion device capable of suppressing shrinkage in the extrusion direction of an extruded rubber extrudate in a short time while having a simple configuration.

  When manufacturing rubber products such as tires, there is an extrusion process in which unvulcanized rubber is extruded by a rubber extrusion device. In the rubber extrusion device, the unvulcanized rubber is plasticized by an internal screw, and is extruded from an extrusion port formed in the die at the tip to form a rubber extrudate molded into a predetermined shape. This rubber extrudate is cut to a predetermined length after cooling. Since rubber has viscoelastic properties, the strain in the extrusion process is stored in the interior as energy, and after cutting due to this, it shrinks (shrinks) mainly in the extrusion direction. If the shrinkage is excessive, a difference from a preset dimension becomes large, and there is a problem that troubles occur in a subsequent process.

  Various methods for solving such problems have been proposed in the past (see, for example, Patent Document 1). In Patent Document 1, the rubber extrudate is vibrated by a vibration device arranged on the downstream side of the extruder to increase the shrinkage speed of the rubber. In this way, the rubber extrudate is sufficiently shrunk to prevent shrinkage in the subsequent process.

  As another countermeasure, a method is known in which a plurality of transport conveyors are arranged in series on the downstream side of the extruder, and the downstream transport conveyor and the transport speed are set slower. In this method, the rubber extrudate is forcibly contracted when the transfer conveyor is transferred to prevent contraction in the subsequent process. However, with these conventional measures, there is a problem that the apparatus becomes large and the time required to suppress the shrinkage becomes long.

JP-A-8-244090

  An object of the present invention is to provide a rubber extrusion device capable of suppressing the shrinkage in the extrusion direction of an extruded rubber extrudate in a short time while having a simple configuration.

  In order to achieve the above object, a rubber extrusion device according to the present invention comprises a cylindrical cylinder, a screw disposed in the cylinder, a head installed at the tip of the cylinder, and a pusher disposed at the tip of the head. In the rubber extrusion apparatus including a die having an outlet, at least the rectifying body extending toward the cylinder side from a predetermined position within a forward projection amount of 10 mm or less from the front end surface of the extrusion port is formed on the die. The rubber pushed out by the screw is installed inside the extrusion flow path, and in the gap in the thickness direction between the extrusion flow path and the rectification body and in the width direction gap between the extrusion flow path and the rectification body. It is configured to pass through and push out from the extrusion port.

  According to the present invention, the rectifying body is installed inside the extrusion flow path formed in the die, and the gap between the extrusion flow path and the thickness direction of the rectification body and between the extrusion flow path and the width direction of the rectification body are set. By passing the rubber extruded by the screw between the gaps, the rubber is extruded from the extrusion port while being in contact with the inner surface of the extrusion flow path and the surface of the rectifier. The strain in the direction orthogonal to the extrusion direction remains in the portion in contact with the inner surface of the rubber extrusion channel and the surface of the rectifier. When these portions are extruded, they exhibit a behavior of extending in the extrusion direction due to this strain, and as a result, shrinkage of the rubber extrudate can be suppressed. In addition, since the rectifier is protruded from the front end surface of the extrusion port, the rubber can be left with the maximum strain in the direction orthogonal to the extrusion direction, and accordingly, the shrinkage of the rubber extrudate is suppressed. The effect is increased. That is, the shrinkage of the rubber extrudate in the extruding direction can be suppressed immediately after extrusion, while having a simple configuration provided with a rectifier without requiring a large structure. This makes it possible to sufficiently suppress the shrinkage of the rubber extrudate in a short time.

  Moreover, the rubber | gum which passed through the clearance gap between an extrusion flow path and a rectification | straightening body because the rectification | straightening body extends toward the cylinder side from the predetermined position where the protrusion amount to the front from the front-end surface of the said extrusion opening is within 10 mm. Since the extrudate is integrated immediately after passing through the front end of the rectifying body, which is in the vicinity of the front end face of the extrusion port, the rubber extrudate does not remain divided by the rectifying body. Therefore, the rubber extrudate can be used without difficulty in the subsequent process.

  Here, for example, the extension length of the rectifier is set to 10 mm or more. According to this specification, distortion in a direction orthogonal to the extrusion direction can be sufficiently applied to the rubber portion that contacts the surface of the rectifying body. Therefore, it is advantageous for suppressing shrinkage in the extrusion direction of the rubber extrudate.

  For example, the rectifier is plate-shaped. Since the resistance to the rubber passing therethrough can be prevented by using a plate-like rectifier, a smooth extrusion operation can be ensured. For example, the plate body is arranged with its plate thickness direction facing the thickness direction of the extrusion port. Alternatively, the rectifier may be arranged with its plate thickness direction facing the width direction of the extrusion port.

It is explanatory drawing which illustrates the rubber extrusion apparatus of this invention by planar view. It is explanatory drawing which illustrates die | dye of FIG. 1 by front view. It is explanatory drawing which illustrates the die | dye and head periphery of FIG. 1 by side surface sectional view. It is explanatory drawing which illustrates the state of the rubber extrudate immediately after the conventional extrusion by sectional view. It is explanatory drawing which illustrates the state of the rubber extrudate immediately after extrusion by the rubber extrusion apparatus of this invention by a cross sectional view. It is explanatory drawing which illustrates the die | dye which installed another rectifier in front view. FIG. 7 is an explanatory diagram illustrating the periphery of the die and the head of FIG. 6 in a side sectional view.

  Hereinafter, a rubber extrusion device of the present invention is explained based on an embodiment shown in a figure.

  A rubber extrusion device 1 of the present invention illustrated in FIGS. 1 to 3 includes a cylindrical cylinder 2, a screw 4 disposed inside the cylinder 2, and a head 3 installed at the tip of the cylinder 2. Yes. A die 5 is attached to the tip of the head 3. An extrusion port 6 is formed in the die 5, and a take-up conveyor 9 is disposed in front of the extrusion port 6.

  A rectifier 8 extends from a predetermined position protruding forward from the front end face of the extrusion port 6 by a predetermined dimension a toward the cylinder 2 side. The extending length b of the rectifying body 8 is, for example, 10 mm or more. The rectifying body 8 has a flat plate shape and is installed at least inside the extrusion flow path 7 formed in the die 5. The rectifying body 8 is fixed to the die 5 via a connecting portion 8 a extending downward from the rectifying body 8, and extends across the extrusion flow path 7 formed in the die 5 and the head 3. The rectifying body 8 can be extended only to the extrusion flow path 7 formed in the die 5, but may be installed inside the extrusion flow path 7 formed in the die 5 and the head 3.

  The predetermined dimension a is set to more than 0 mm and not more than 10 mm. The upper limit value of the extension length b is, for example, about 100 mm, but is not limited to this. Moreover, it is preferable to extend the rectifying body 8 by 10 mm or more from the front end face of the extrusion port 6 toward the cylinder side 2.

  In this embodiment, a single flat plate-like rectifying body 8 is arranged with the plate thickness direction facing the thickness direction of the extrusion port 6, and is arranged at the center in the width direction of the extrusion port 6. The gaps w and w in the width direction between the extrusion channel 7 and the rectifier 8 are 10 mm or more. The left and right clearances w and w can be different, but they should be the same. The gaps t1 and t2 in the thickness direction between the extrusion channel 7 and the rectifier 8 are each 0.5 mm or more. The upper and lower gaps t1 and t2 can be different, but are preferably the same.

  When extruding the rubber extrudate R by the rubber extrusion device 1 in the production line, a predetermined amount of unvulcanized rubber and compounding agent are charged into the extruder 1. These materials are mixed and kneaded by the rotating screw 4. The unvulcanized rubber that has been mixed and kneaded is softened to some extent (plasticized), molded from the extrusion port 6 to the cross-sectional shape of the extrusion port 6, and extruded into a sheet as an unvulcanized rubber extrudate R. .

  At this time, the rubber pushed forward by the screw 4 passes through the gaps w, w, t1, and t2 between the extrusion flow path 7 and the rectifier 8, and is pushed out from the extrusion port 6. That is, the rubber extruded from the cylinder 2 side by the screw 4 is extruded from the extrusion port 6 while being in contact with the inner surface of the extrusion flow path 7 and the surface of the rectifying body 7.

  Here, in the conventional rubber extrusion apparatus, the rubber extrudate R is extruded from the extrusion port 6 while being in contact with the inner surface of the extrusion flow path 7. At this time, strain in a direction orthogonal to the extrusion direction remains in a portion that contacts the inner surface of the extrusion flow path 7. The inventor of the present invention observes and analyzes the shapes of a large number of rubber extrudates R by a conventional rubber extruding device, and as shown in FIG. As a result, it has been found that it exhibits a behavior of extending in the tip direction (extrusion direction) due to this strain.

  Therefore, the tip of the rubber extrudate R has a shape in which the outer peripheral portion relatively protrudes in the tip direction (extrusion direction) and the central portion of the cross section is relatively recessed backward. That is, if a strain is left in the direction orthogonal to the extrusion direction immediately before the rubber extrudate R is extruded, the portion extends in the extrusion direction after extrusion, and accordingly, shrinkage of the central portion of the cross section to be contracted is suppressed. To do. The present invention utilizes this principle.

  As illustrated in FIG. 5, in the rubber extrusion device 1 of the present invention, strain in a direction orthogonal to the extrusion direction remains in a portion that contacts the inner surface of the extrusion flow path 7 and the surface of the rectifying body 8. When the portion where the strain remains is extruded, the portion that extends in the extrusion direction due to the strain exhibits a behavior, so that the portion that extends in the extrusion direction increases compared to the conventional case. As a result, the contraction of the central portion of the cross section to be contracted is suppressed, and the contraction of the rubber extrudate R is suppressed as a whole.

  Moreover, in the present invention, since the rectifying body 8 is protruded from the front end face of the extrusion port 6, strain in the direction orthogonal to the extrusion direction can be left to the maximum extent in the rubber. Accordingly, the effect of suppressing the shrinkage of the rubber extrudate R can be maximized.

  Therefore, according to the rubber extrusion device 1 of the present invention, the rubber extrudate R is contracted in the extrusion direction immediately after extrusion, while having a simple structure provided with the rectifying body 8 without requiring a large structure. It becomes possible to suppress. That is, on the take-up conveyor 9, the shrinkage is settled in a short time without performing a process such as waiting for a long time to sufficiently shrink the rubber extrudate R. Therefore, the shrinkage of the rubber extrudate R can be sufficiently suppressed in a short time as compared with the conventional case.

  In addition, the forward projecting dimension a from the front end face of the extrusion port 6 of the rectifying body 8 is 10 mm or less, and the rubber extrudate R has gaps t1 and t2 in the thickness direction between the extrusion flow path 7 and the rectifying body 8 and Since the extrusion flow path 7 and the rectifying body 8 are pushed through the gaps w and w in the width direction, the rubber primarily divided by the rectifying body 8 is divided in the extruded flow. Immediately, the split surfaces join together naturally. That is, the divided surfaces of the rubber extrudate R are automatically joined together by the swell of unvulcanized rubber divided by the rectifier 8 (property to spread).

  Therefore, when the split surfaces of the rubber extrudate R are joined, the split surfaces disappear and are conveyed to the next process by the take-up conveyor 9. Therefore, the rubber extrudate R can be used as it is sent to the next process of the production line.

  When the extending length b of the rectifying body 8 is set to 10 mm or more, distortion in a direction orthogonal to the extrusion direction can be sufficiently applied to the rubber portion that contacts the surface of the rectifying body 8. Therefore, it is advantageous for suppressing the shrinkage of the rubber extrudate R in the extrusion direction. A suitable extension length b is, for example, 10 mm to 50 mm.

  If the front end position of the rectifying body 8 is set to a position exceeding 10 mm forward from the front end face of the extrusion port 6, the rubber extrudate R is likely to remain divided by the rectifying body 8, and the post-process This will cause problems in use. Therefore, by setting the predetermined dimension a to 10 mm or less, it is possible to obtain a rubber extrudate R that can be used as it is in the subsequent process without any problem.

  In addition to the plate shape, the rectifying body 8 can have various shapes such as a cone shape and a pyramid shape. Since the resistance to the rubber passing therethrough can be prevented by using the plate-like rectifier 8, a smooth extrusion operation can be ensured. The flat plate-like rectifying body 8 is extended in the direction along the extending direction of the extrusion channel 7 so that the plane having a relatively large area faces the inner surface of the extrusion channel 7 having a relatively large area. . For example, in the case of the extrusion channel 7 having a quadrangular cross section, a rectifying body 8 having a quadrangular cross section is used, and in the case of the extrusion channel 7 having a circular cross section, the rectifying body 8 having a circular cross section is used. 7 and the rectifier 8 have the same cross-sectional shape (similar shape).

  If the cross-sectional area of the rectifying body 8 is excessive with respect to the cross-sectional area of the extrusion channel 7, the resistance to rubber becomes excessive, the rubber temperature becomes too high, or an excessive external force acts on the rectifying body 8. Such problems arise. Therefore, the ratio of the cross-sectional area of the rectifier 8 to the cross-sectional area of the extrusion channel 7 is preferably 40% or less, more preferably 5% to 30%, and still more preferably 5% to 20%.

  A plurality of rectifying bodies 8 can also be provided. In this case, the cross-sectional view of the extrusion flow path 7 is arranged such that the maximum separation distance between the surface of the rectifying body 8 and the inner surface of the extrusion flow path 7 and the maximum separation distance between adjacent rectification bodies 8 are 100 mm or less. It is preferable. Specifically, when the extrusion port 6 has a rectangular shape with a width dimension of 300 mm and a height dimension of 50 mm, for example, three rectifier bodies 8 with a width dimension of 10 mm and a height dimension of 5 mm are arranged in the width direction in the extrusion flow path 7. It is preferable that the widthwise interval between each other, the rightmost rectifier 8 and the right inner surface of the extrusion port 6, and the leftmost rectifier 8 and the left inner surface of the extrusion port 6 be equally spaced.

  The embodiment of the rubber extrusion device 1 illustrated in FIGS. 6 and 7 is different from the previous embodiment only in the specifications of the rectifying body 8. In this embodiment, a single plate-like rectifying body 8 is disposed at the center in the width direction of the extrusion port 6 with its thickness direction directed in the width direction of the extrusion port 6. A notch 8 b is formed at a corner below the tip of the rectifier 8.

  The rectifier 8 extends from the front end surface of the extrusion port 6 toward the cylinder 2 from a predetermined position protruding forward by a predetermined dimension a. The extending length b of the rectifying body 8 is, for example, 10 mm or more. The flat plate-like rectifier 8 is installed at least inside the extrusion flow path 7 formed in the die 5. An upper end portion of the rectifying body 8 is fixed to the inner surface of the extrusion flow path 7, and a lower end portion of the rectification body 8 is fixed to the inner surface of the extrusion flow path 7, so that the extrusion flow path 7 formed in the die 5 and the head 3 It extends across. The rectifying body 8 can be extended only to the extrusion flow path 7 formed in the die 5, but may be installed inside the extrusion flow path 7 formed in the die 5 and the head 3.

  The predetermined dimension a protruding forward from the front end face of the extrusion port 6 of the rectifier 8 is set to be greater than 0 mm and not greater than 10 mm. The extension length b is 10 mm or more, and the upper limit is, for example, about 100 mm. Moreover, it is preferable to extend the rectifying body 8 by 10 mm or more from the front end face of the extrusion port 6 toward the cylinder side 2.

  The gaps w and w in the width direction between the extrusion channel 7 and the rectifier 8 are 10 mm or more. The left and right clearances w and w can be different, but they should be the same. A gap t in the thickness direction between the extrusion flow path 7 and the rectifier 8 is 0.5 mm or more. That is, the gap t in the thickness direction is provided by forming the notch 8 b in the rectifying body 8. The gap t can be provided on the upper side of the rectifier 8 by forming a notch 8b on the upper side. Alternatively, a pair of notches 8b can be formed on the upper side and the lower side of the rectifying body 8, and the gap t can be provided on the upper side and the lower side.

  In the rubber extrusion device 1 of this embodiment, the rubber extruded forward by the screw 4 passes through the gaps w, w, t between the extrusion flow path 7 and the rectifier 8 and is extruded from the extrusion port 6. The rubber extrudate R is likely to be divided into two in the width direction by the rectifier 8. However, since the gap t is provided by the notch 8b formed in the rectifying body 8, the rubber extrudate R can be integrated immediately after passing through the front end of the rectifying body 8, and the rubber extrudate R is converted into a post-process. Can be used without any trouble.

  The notch 8b is set at a position retracted backward from the front end face of the extrusion port 6 by a predetermined dimension c. In order to reliably integrate the rubber extrudate R immediately after passing through the front end of the rectifying body 8, the predetermined dimension c may be set to 1 mm or more.

  The rubber extrudate was extruded using an extruder equipped with an extrusion channel having a circular cross section and an extrusion port. At this time, extrusion was carried out by changing only the presence or absence of the rectifying body. The rectifying body is flat and extends 10 mm toward the cylinder from the position protruding 2 mm forward from the front end face of the extrusion port, and is installed so as to cross the extrusion flow path as illustrated in FIGS. 6 and 7. did. The extruded rubber was extruded from the extrusion port through a gap in the thickness direction between the extrusion flow path and the rectifying body and a gap in the width direction between the extrusion flow path and the rectifying body. The ratio of the cross-sectional area of the rectifier to the cross-sectional area of the extrusion channel was about 10%.

  For two types of samples that differed only in the presence or absence of a rectifying body, the shrinkage in the extrusion direction was measured by comparing immediately after extrusion with the time when the shrinkage in the extrusion direction was sufficiently reduced. As a result, it was confirmed that the rubber extrudate obtained by extruding with the rectifying member had a shrinkage rate in the extruding direction reduced by about 40% as compared with the rubber extrudate extruded without the rectifying member.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Cylinder 3 Head 4 Screw 5 Die 6 Extrusion port 7 Extrusion flow path 8 Rectifier 8a Connection part 9 Take-out conveyor R Rubber extrudate

Claims (5)

In a rubber extrusion device comprising a cylindrical cylinder, a screw arranged in the cylinder, a head installed at the tip of the cylinder, and a die arranged at the tip of the head and having an extrusion port,
A rectifying body extending toward the cylinder side from a predetermined position within a forward projection amount of 10 mm or less from the front end face of the extrusion port is installed at least inside the extrusion flow path formed in the die, and the extrusion flow The rubber extruded by the screw is passed through the gap in the thickness direction between the path and the rectifying body and the gap in the width direction between the extrusion flow path and the rectifying body, and extruded from the extrusion port. A rubber extrusion device.   The rubber extrusion device according to claim 1, wherein an extension length of the rectifying body is 10 mm or more.   The rubber extruding device according to claim 1, wherein the rectifying body is plate-shaped.   The rubber extruding apparatus according to claim 3, wherein the flow straightening body is disposed with a plate thickness direction directed in a thickness direction of the extrusion port.   The rubber extruding apparatus according to claim 3, wherein the rectifying body is arranged with a plate thickness direction directed in a width direction of the extrusion port.

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