JP4089954B2 - Extruded rubber sheet manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an extruded rubber sheet (hereinafter also simply referred to as “rubber sheet”) (hereinafter also simply referred to as “manufacturing method”) and a rubber extrusion base used therefor (hereinafter also simply referred to as “base”). Specifically, the present invention relates to a method for producing an extruded rubber sheet having a taper shape in which the end portion of the sheet is reduced to zero gauge as much as possible, and a rubber extrusion die used therefor.
[0002]
[Prior art]
In general, when producing rubber sheets by continuous extrusion of rubber, a rolling sheeting method is used in which a sheet-like unvulcanized rubber material extruded by an extruder is rolled into a final shape by a roller die profiled into a roll. Is used.
[0003]
In such continuous rubber sheeting, it is important to ensure the dimensional stability of the resulting rubber sheet. On the other hand, for example, in Patent Document 1, the speed of the extruder is controlled by adding correction values to parameters such as the required discharge capacity of the extruder, the dimensions of the sheet-like material, and the operating speed of the extruder. A technique related to a method for controlling the extrusion of a sheet-like material that enables the extruded sheet-like material to be extruded is described.
[0004]
Further, as a technique for improving dimensional stability by processing after extrusion, Patent Document 2 discloses a method for rolling a extruded unvulcanized rubber with a calender roll to form a rubber sheet, and then a predetermined amount for the entire width of the rubber sheet. A method of stabilizing the size of a rubber sheet in a rubber rolling apparatus is described in which the cooling is performed while pressing at a pressure of 2 to accelerate the stabilization of the size of the rubber sheet by cooling.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-34735 (Claims)
[Patent Document 2]
JP-A-5-245864 (Claims etc.)
[0006]
[Problems to be solved by the invention]
On the other hand, in such a sheeting manufacturing method, the extrusion die used for supplying unvulcanized rubber from the extruder to the roller die is generally a very simple one having a straight rubber flow path and a rectangular section. Is used. However, depending on the final shape of the target rubber sheet, the shape and weight distribution of the rubber supplied from the die to the roller die is different from the profile processing of the roller die. There was a case that it was incompatible and affected the shape of the rubber sheet.
[0007]
In particular, when both ends of the rubber sheet in the sheet width direction are sharply tapered so as to approach zero as much as possible from the flat gauge, the amount of rubber supplied exceeds the allowable limit of the profile shape of the roller die at both ends of the tapered shape. In some cases, the obtained rubber sheet has a problem that a wavy shape defect occurs at the tapered end. When such a undulating shape defect occurs, when the rubber sheet is delivered to the next process, depending on the height of the undulating portion, the undulating portion may interfere with the frame or the like, and the conveyor belt may become entangled, In order to supply rubber that does not generate waviness at the tapered end, it is necessary to form a die suitable for a roll profile. It was required to realize.
[0008]
In any of the techniques described in Patent Documents 1 and 2 mentioned above, any problem specific to extruding a rubber sheet having a special shape such as a rubber sheet having an end tapered shape is not considered.
[0009]
Therefore, an object of the present invention is to eliminate waviness when manufacturing a rubber sheet having a special shape, for example, a rubber sheet having sharp tapered shapes at both ends in the sheet width direction, in continuous flat rubber sheeting. An object of the present invention is to provide a method for producing an extruded rubber sheet capable of forming a good tapered end portion, and a rubber extrusion die used therefor.
[0010]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention correspond not only to the roller die that determines the final shape of the sheeting, but also to the die for extrusion that supplies a rubber material to the roller die. By adopting the shape, it was found that a more stable sheet shape, for example, a tapered end portion without undulations, can be obtained upon molding in a roller die, and the present invention has been completed.
[0011]
In order to solve the above-mentioned problems, the extruded rubber sheet manufacturing method of the present invention is a method in which an unvulcanized rubber material is supplied from an extruder to a roller die via a rubber extrusion die and profiled with the roller die. In the method of manufacturing an extruded rubber sheet that is molded into a sheet shape,
As the rubber extrusion base, a base is used in which the shape of the rubber supply hole is substantially similar to the roll profile shape in the roller die, and the roll profile shape is reduced. To do.
[0012]
The production method of the present invention is, for example, when the extruded rubber sheet is formed into a sheet shape having a tapered end in the width direction, and in particular, when formed in a tapered shape such that the end in the width direction is substantially zero gauge. It is valid. In particular, it can be suitably used when a tire tread is molded as an extruded rubber sheet.
[0013]
The rubber extrusion die of the present invention is used in the method for producing an extruded rubber sheet of the present invention.
[0014]
In the base of the present invention, the first flow path has a portion where the rubber flow path from the head to the rubber supply hole has a tapered shape extending from the cross-sectional shape of the head to the cross-sectional shape of the rubber supply hole. And a second flow path having the same cross-sectional shape as the shape of the rubber supply hole, and the first flow path and the second flow path are substantially equidistant. More preferably, it is provided. Further, it is more preferable that the tapered portion in the first flow path is shorter in the sheet thickness direction than in the sheet width direction and is provided closer to the head.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The method for producing an extruded rubber sheet according to the present invention comprises supplying an unvulcanized rubber material from an extruder to a roller die through a rubber extrusion die, and forming the extruded rubber sheet into a sheet shape profiled by the roller die. The present invention relates to a series of steps for obtaining a sheet, and is characterized in that the rubber extrusion die of the present invention described in detail below is used as the rubber extrusion die.
[0016]
In (a), (b), (c) and (d) of FIG. 1, a front view, a plan view, a rear view and a cross-sectional view (in (a)) of a preferred embodiment of the rubber extrusion base of the present invention are shown. (Cross section along line AA) is shown respectively. The arrows in the figure indicate the direction of rubber flow. The illustrated base 1 is used when an extruded rubber sheet is manufactured in a sheet shape having a tapered end in the width direction, and the shape of the rubber supply hole 2 corresponds to the tapered sheet shape. It is formed into a shape. That is, in the base 1 of the present invention, the rubber supply hole 2 that determines the final shape of the rubber material supplied from the base 1 to the roller die is formed in a shape similar to the final sheet shape profiled on the roller die. ing.
[0017]
As a result, since the rubber volume is evenly distributed in the rubber supply holes 2, it is possible to prevent the rubber distribution amount from being excessive in the rolled sheeting portion at the taper end, and the rubber that has conventionally been produced in accordance with this. It is possible to suppress shape defects such as the occurrence of undulation caused by escape. That is, since the rubber material supplied through the die 1 of the present invention appropriately matches the roll profile processing of the roller die, it is possible to obtain an extruded rubber sheet having a stable shape without any shape defects such as waving. Obtainable.
[0018]
Specifically, the rubber supply hole 2 is formed so as to be substantially similar to the sheet shape of the roller die and smaller than the sheet shape. Thereby, it is possible to obtain a well-balanced die 1 suitable for a roll profile, and in particular, when forming a sheet-like rubber sheet having a tapered end in the width direction, as shown in the drawing, the end in the width direction is particularly preferable. In the case of forming a sharp taper-shaped rubber sheet having a substantially zero gauge, it is possible to ensure the stability of the tapered end portion and appropriately prevent the shape defect.
[0019]
Here, the reason why the shape of the rubber supply hole 2 is formed to be smaller than the roll profile is in consideration of the expansion due to the rubber swell. This also applies to the profile processing of the roller die, and is determined by the reduced shape in the order of the final rubber sheet shape, the roll profile shape in the roller die, and then the shape of the rubber supply hole 2 of the base 1. Is done. Since this reduction ratio varies depending on the rubber type to be used, each reduced shape needs to be determined from time to time by a laboratory evaluation or the like for the final rubber sheet shape, but the means for suppressing shape defects such as undulations according to the present invention itself. The same applies in any case. For example, when a rubber material for an inner tire is used, the reduction ratio of the base 1 from the final rubber sheet shape is 80 to 90% over the entire sheet width, and the taper at both ends, depending on the thickness setting. Only the width of the portion can be set to about 45 to 60%.
[0020]
As shown in FIG. 1 (b) and FIG. 1 (d), which is a cross-sectional view taken along line AA in FIG. 1 (a), the rubber flow path of the base 1 is connected to the rubber supply hole 2 from the head 3. The first flow path X having a gently tapered portion extending from the cross-sectional shape of the head 3 to the cross-sectional shape of the rubber supply hole 2 is the same as the shape of the rubber supply hole 2. It is preferable to form the second flow path Y having a cross-sectional shape. The rubber flow path of the base 1 is formed by the first flow path X and the second flow path Y, so that the rubber flow is made uniform and stable, and the rubber distribution is distributed in the cross-sectional shape of the rubber supply hole 2. It is possible to adjust in If the rubber flow path is formed linearly, the rubber filling degree varies in the final flow path, and as a result, defects such as undulation are likely to occur. That is, the rubber gauge can be stabilized by providing the second flow path Y related to the final shape of the rubber sheet as a final mold forming section of a certain section.
[0021]
Further, as shown in FIGS. 1B and 1D, it is more preferable that the first flow path X and the second flow path Y are provided at substantially equal distances. The above-described rubber flow uniformity and stabilization effect can be obtained more appropriately. Further, as shown in the figure, the first flow path X has a tapered portion that is shorter in the sheet thickness direction than in the sheet width direction and provided closer to the head 3. preferable. That is, the cross-sectional shape of the rubber flow path is preferably narrowed down to the cross-sectional shape of the rubber supply hole 2 earlier in the sheet thickness direction (the flow in the first flow path X in FIG. 1 (D)). The final gauge can be further stabilized by providing the path Z) and the subsequent final molding section longer in the thickness direction.
[0022]
The method for producing an extruded rubber sheet of the present invention using such a base 1 can be suitably used, for example, for molding a tire tread as a rubber sheet having a tapered end in the width direction. In the present invention, as described above, in the case where the tread is formed in a tapered shape such that the end in the width direction is substantially zero gauge, the occurrence of undulation failure is prevented, and a tread having high shape stability is obtained. It is effective for manufacturing.
[0023]
【The invention's effect】
As described above, according to the present invention, particularly in a continuous flat rubber sheeting, a rubber sheet having a special shape, for example, a rubber sheet having both ends in the sheet width direction formed into a sharp tapered shape is manufactured. In this case, it is possible to provide a method for producing an extruded rubber sheet capable of forming a good tapered end portion without undulations, and a rubber extrusion base used for the method.
[Brief description of the drawings]
1A is a front view, FIG. 1B is a plan view, FIG. 1C is a rear view, and FIG. 1D is an AA in FIG. Each of the cross-sectional views along the line is shown.
[Explanation of symbols]
1 Rubber Extrusion Base 2 Rubber Supply Hole 3 Head X First Channel Y Second Channel Z Channel

Claims (4)

In the method for producing an extruded rubber sheet, an unvulcanized rubber material is supplied from an extruder to a roller die via a rubber extrusion die, and is molded into a sheet shape profiled with the roller die.
As the rubber extrusion base, a base is used in which the shape of the rubber supply hole is substantially similar to the roll profile shape in the roller die, and the roll profile shape is reduced. A method for producing an extruded rubber sheet.   The method for producing an extruded rubber sheet according to claim 1, wherein the extruded rubber sheet is formed into a sheet shape having a tapered end in the width direction.   The method for producing an extruded rubber sheet according to claim 2, wherein the extruded rubber sheet is formed in a taper shape such that the end in the width direction is substantially zero gauge.   The method for producing an extruded rubber sheet according to claim 2 or 3, wherein a tire tread is molded as the extruded rubber sheet.

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