JP4077571B2 - Rubber crawler manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel method for producing a rubber crawler, and more particularly, to provide a method for producing an internally driven rubber crawler.
[0002]
[Prior art]
The rubber crawler is largely divided into two according to the driving method, and the so-called inner drive type rubber crawler is used at a relatively high speed. This inner drive type rubber crawler generally has no metal core embedded in the rubber, and steel cords are embedded in a row in the longitudinal direction of an endless rubber crawler to provide a driving force on the inner peripheral surface. Protrusions for transmission and prevention of wheel removal are formed with a constant pitch, and lugs are formed on the outer peripheral surface.
[0003]
In the production of such a rubber crawler, the lower mold is formed with a cavity (a) for forming the inner peripheral surface of the rubber crawler and the cavity (b) for forming a projection at a constant pitch, and the other upper mold is a rubber crawler. And a cavity (d) for forming a lug. The cavities (A) formed by these upper and lower molds are filled with unvulcanized rubber and vulcanized, but fluidity is added to the rubber during the vulcanization and the cavities (A) are completely filled. Will be. As a result, the steel cord stretched in the cavity (A) is caused to flow along with the flow of the rubber material to cause turbulence, and it is difficult to make it as designed.
[0004]
Specifically, since the rubber flow in the cavity (A) flows into the cavity (b), the steel cord is drawn into the cavity (b), and the steel cord is curved toward the protrusion as the rubber crawler obtained. Will end up. That is, the steel cord is not embedded linearly in the longitudinal direction of the rubber, but is embedded in a state of rising toward the protrusion. When this is seen in the longitudinal direction of the rubber crawler, the steel cord is buried in a pulsating state between the protruding portion and the non-projecting portion.
[0005]
Further, even when the rubber crawler is viewed from the plane, the steel cord cannot be pressed because there is no cored bar, and a disturbance such as meandering in the width direction may occur. That is, a rubber crawler without a metal core has nothing to block the flow of the steel cord at the time of molding, and the steel cord is caused to flow by the flow of rubber in the cavity (A) by the upper and lower molds, so that the same plane in the rubber There will often be cases where they are not buried on top.
[0006]
In particular, the mesh position of the steel cord and the pitch accuracy of the protrusions have a great influence on the meshing of the rubber crawler without a core metal with the sprocket. If disturbance occurs, a partial meshing failure with the sprocket is caused, which causes power loss and a decrease in durability of the rubber crawler.
[0007]
[Problems to be solved by the invention]
The present invention is a rubber crawler without a cored bar, which eliminates the disturbance of the steel cord and embeds the steel cord on almost the same plane in the rubber, thereby preventing the power loss from being lowered and improving the durability of the rubber crawler. The purpose is to provide a new manufacturing method.
[0008]
[Means for Solving the Problems]
The present invention employs the following configuration in order to achieve the above object. That is, a lug is formed with a lower mold having a cavity (a) forming the inner peripheral surface of the rubber crawler and a cavity (b) forming a protrusion of the rubber crawler, and a cavity (c) forming the outer peripheral surface of the rubber crawler. A rubber crawler molding cavity (A) is formed by overlapping an upper mold having a cavity (d), and an unvulcanized rubber member and a steel cord constituting each part of the rubber crawler are overlapped and added in the cavity (A). This is a rubber crawler manufacturing method that performs vulcanization molding, in which a pre-pressed protruding rubber piece is inserted into the cavity (b), and the rubber crawler inner surface rubber and steel cord are sequentially embedded in the cavity (A). those characterized with rubber, and the rubber rubber crawler outer surface, superimposed and rubber Gomuragu, that obtained by vulcanization molding to close said lower die and said upper mold A.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
As described above, since a force is also applied to the steel cord together with the rubber flow in the cavity during molding of the rubber crawler, this arrangement is liable to be disturbed. In the case of an inner drive type rubber crawler without a cored bar, there is nothing to prevent the steel cord from being disturbed, and the occurrence of the disorder is inevitable.
[0010]
The present invention has been made in particular in consideration of this point, and during the production of the rubber crawler, the steel cord is disturbed particularly corresponding to the protrusions. More specifically, a pre-pressed protruding rubber piece is set in the cavity (b) of the lower mold and used for vulcanization molding of a rubber crawler.
For this reason, the protruding rubber piece is not so fluid in the manufacturing process of the rubber crawler, and therefore the steel cord is not disturbed.
[0011]
However, in order to obtain such a protruding rubber piece, it is usually extruded as a long body that is approximately the same shape as the outer shape of the protruding rubber crawler in the front-rear direction, and then cut according to the thickness of the protrusion in the front-rear direction. To obtain a projection material, or extrusion-molded as a long body having substantially the same shape as the outer shape of the projection in the width direction, and then cut as approximately the same as the length of the projection in the left-right direction. It is set inside and pre-pressed to obtain a protruding rubber piece. This prepress is performed under the conditions for rubber vulcanization. In other words, when the pre-pressed protruding rubber piece is used for rubber crawler production, it is pre-pressed to such an extent that the shape is not changed so much by vulcanization (pressing and heating). Therefore, the press treatment is performed at about 120 to 130 ° C. or lower than the vulcanization temperature for about 2 to 3 minutes.
In some cases, a long body may be obtained by rubber extrusion, pre-pressed, and then cut as a protruding rubber piece. This is because it is difficult to cut a completely vulcanized rubber, but it is relatively easy to cut a rubber material treated under the prepress conditions described above.
[0012]
In addition, in order to improve wear resistance, for example, a nylon rod or the like may be embedded in the protrusion on the protrusion as a rubber crawler, but in this case, a groove is formed to a position where the rod is embedded in advance during extrusion molding. It is formed, cut, and a rod is inserted into this groove during pre-pressing. If necessary, a rubber piece covering the rod is further stacked and pre-pressed to obtain a protruding rubber piece.
[0013]
In the extrusion molding of the projection material, it is not always necessary to have a shape that substantially matches the outer shape of the projection from the beginning of extrusion, and after extrusion, and bending these after cutting, it is substantially the same as the outer shape of the projection. It may be a projection material representing an outer shape. That is, an unvulcanized rubber material provided with a folding line may be obtained, then cut substantially in accordance with the thickness of the projection, and bent with the folding line to obtain a projection material, or a protruding rubber piece in which a rod is embedded In this case, the protruding rubber piece can be obtained relatively easily if the rod is inserted at the time of bending.
[0014]
【Example】
Hereinafter, the rubber crawler of the present invention will be described in more detail with reference to the drawings.
The manufacturing process of the rubber crawler of the present invention will be described with reference to FIG. 1. The lower mold 11 is formed with a cavity (a) for forming the inner peripheral surface of the rubber crawler and a cavity (b) with a constant pitch for forming protrusions. Has been. On the other hand, the upper mold 12 includes a cavity (c) that forms the outer peripheral surface of the rubber crawler and a cavity (d) that forms a lug. The unvulcanized rubber and steel cord are set in the cavity (A) formed by the upper and lower molds 11 and 12 and vulcanized.
[0015]
In the production of a conventional rubber crawler, the unvulcanized rubber for projection molding in the cavity (A), the unvulcanized rubber constituting the inner peripheral surface of the rubber crawler, the steel cord, and the outer peripheral surface of the rubber crawler are configured. The unvulcanized rubber and the unvulcanized rubber constituting the lug are overlapped and vulcanized and molded by pressurization and heating. In the present invention, the unvulcanized rubber constituting the protrusions In order to prevent fluidity during vulcanization, a rubber crawler is manufactured by fitting a pre-pressed protruding rubber piece 30 into the cavity (b).
[0016]
FIG. 2 is a diagram illustrating a process of forming the pre-pressed protruding rubber piece 30. That is, the first step is a step of extruding the protrusion rubber material 30A (unvulcanized rubber material) by extruding with a rubber extruder, and the outer shape of the protrusion rubber material 30A is substantially the same as the outer shape of the rubber crawler protrusion in the front-rear direction. It is the same shape 30a. Next, in the second step, the projection material 30B is cut by cutting with a length 30b substantially the same as the thickness of the projection. Then, in the third step, this is pre-pressed. The protruding material 30B is set in the cavity (e) of the pre-press mold 40, and pre-pressing is performed on the protruding material 30B at a temperature of 120 ° C. for 2 minutes. 30 is obtained. The obtained protruding rubber piece 30 is semi-vulcanized by pre-pressing as described above, and exhibits a property that does not relatively change shape under vulcanization conditions.
The outer shape of the rubber material for the protrusion is substantially the same as the outer shape in the width direction of the protrusion of the rubber crawler, and may then be cut into a protrusion material by cutting with a thickness approximately the same as the thickness of the protrusion in the front-rear direction. .
[0017]
A rubber crawler is manufactured using the protruding rubber piece 30. First, the protruding rubber piece 30 is set in the cavity (b), and further, a rubber crawler inner surface rubber 31 and a steel cord 32 are sequentially embedded in the cavity (A). The rubber 33, rubber crawler outer surface rubber 34, and rubber lug rubber 35 (both are unvulcanized rubber) are stacked, and the upper and lower molds 11 and 12 are closed and vulcanized. Of course, depending on the case, a fiber reinforcing layer (not shown) can be stacked on the inner side and / or the outer side of the coated rubber 33.
[0018]
Thus, in the production of the rubber crawler of the present invention, the protruding rubber piece 30 has almost no fluidity at the time of vulcanization molding. Therefore, the steel cord 32 does not have a structure that undulates to the protruding rubber piece 30 side, and the rubber The crawler is embedded in a straight line at a predetermined position.
[0019]
When the rubber crawler is used for high speed running, it is preferable to form a uniform endless shape. For example, the lower mold 11 has an endless structure, and a cavity (b) is formed at a constant pitch in the center. ) Set the protruding rubber piece 30 inside, and the steel cord 32 is continuously spirally wound on the cavities (a) and (b) of the lower die 11, and then the upper die 12 is closed and unvulcanized at each part. It is preferable to obtain the rubber by integrally vulcanization molding.
[0020]
FIG. 3 is a cross-sectional view of the rubber crawler 1 obtained by the manufacturing method of the present invention. 2 is a protrusion formed by protruding from the inner peripheral surface of the rubber crawler, and 3 is a lug formed on the outer peripheral surface. A steel cord 4 is embedded in the longitudinal direction of the rubber crawler 1. In this example, nylon fiber layers 5 and 6 are embedded inside and outside the steel cord 4. In the rubber crawler 1, the protrusion 2 is composed of the pre-pressed protrusion rubber piece 30 according to the present invention, and the fluidity of the protrusion rubber piece 30 is suppressed when the rubber crawler 1 is vulcanized. In addition, the steel cord 4 is embedded while being kept substantially straight in the longitudinal direction without flowing toward the protrusion 2 side.
[0021]
In the inner drive type rubber crawler, a sprocket or a roller (not shown) often comes into contact with the left and right side surfaces of the protrusion, and this surface often wears. For this reason, for example, a nylon rod may be embedded in the left-right direction of the protrusion. In such a case, when extruding the protrusion rubber material 30A, the base is changed as shown in FIG. A protrusion rubber material 30A is obtained as a shape having a groove 30c in the direction, and this is cut and a rod 3d is fitted into the groove 30c, and this is covered with an unvulcanized rubber piece 30e in some cases to form a protrusion material 30B. It is good to set this in a prepress mold and to perform a prepress process.
[0022]
The protrusion rubber material 30A obtained by extrusion molding does not have to be cut into substantially the same shape as the protrusions after extrusion molding. In some cases, the cut rubber material 30A is bent to form a protrusion shape. It may be of substantially the same shape. For example, as shown in FIG. 5, the rubber material 30 </ b> A extruded in four blocks by three lines 30 f can be bent along each line 20 f so as to have substantially the same shape as the protruding shape as a whole. Of course, it goes without saying that the present invention can be similarly applied to a case where a rod is embedded.
[0023]
【The invention's effect】
In the present invention, since the steel cord is disturbed particularly in the projection portion during the production of the rubber crawler, the projection forming rubber is pre-pressed in advance, and thus the projection rubber piece is a process of producing the rubber crawler. The steel cord was not so disturbed by the rubber flow.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram of a rubber crawler according to the present invention.
FIG. 2 is a diagram showing a process of forming a protruding rubber piece.
FIG. 3 is a cross-sectional view of a rubber crawler obtained by the present invention.
FIG. 4 is a diagram showing a molding process of another example of the protruding rubber piece.
FIG. 5 is a diagram showing a molding process of still another example of the protruding rubber piece.
[Explanation of symbols]
A: Cavity formed by upper and lower molds,
a. Cavity that forms the inner peripheral surface of the rubber crawler,
b. Cavity that forms the protrusion of the rubber crawler,
c. Cavity that forms the outer peripheral surface of the rubber crawler,
d. Cavity forming rubber crawler lug,
1. Rubber crawler obtained by the present invention,
2 ... Protrusions,
3 ... Rug,
4. Steel cord,
5, 6 ... fiber layer,
11 ... Lower mold,
12 ... Upper mold,
30 ... Pre-pressed protruding rubber piece,
30A ... Extruded rubber material for protrusions,
30B ... projection material,
30c ... groove,
30d. Rod,
31 ... rubber crawler inner rubber,
32 ... Steel cord,
33. Coated rubber,
34 ... rubber crawler outer surface rubber,
35. Rubber for rubber lugs,
40: Prepress mold.

Claims (5)

A lower mold having a cavity (a) that forms the inner peripheral surface of the rubber crawler and a cavity (b) that forms a protrusion of the rubber crawler, a cavity (c) that forms the outer peripheral surface of the rubber crawler, and a cavity that forms a lug ( A rubber crawler molding cavity (A) is formed by overlapping the upper mold having d), and an unvulcanized rubber member and a steel cord constituting each part of the rubber crawler are stacked in the cavity (A) to perform vulcanization molding. A rubber crawler manufacturing method ,
Insert a pre-pressed protruding rubber piece into the cavity (b) ,
Furthermore, in the cavity (A), the rubber for the inner surface of the rubber crawler, the coated rubber having the steel cord embedded therein, the rubber for the outer surface of the rubber crawler, and the rubber for the rubber lug are sequentially stacked.
A process for producing a rubber crawler, wherein the upper mold and the lower mold are closed and vulcanized . The protrusion rubber piece is obtained by extrusion molding an unvulcanized rubber body approximately matching the outer shape of the protrusion, and then cut substantially in accordance with the protrusion size to obtain a protrusion material, which is pre-press molded. The method for producing a rubber crawler according to claim 1. The protruding rubber piece is obtained by extrusion molding an unvulcanized rubber body that substantially matches the size of the protrusion and is provided with a groove, and is then cut to approximately match the thickness of the protrusion, and a wear prevention rod is fitted in the groove. The method for producing a rubber crawler according to claim 1, wherein the protrusion material is obtained by pre-press molding . The protruding rubber piece is obtained by extruding an unvulcanized rubber body having a folding line, then cutting it, bending the bending line to obtain a protruding material, and pre-press molding it. A process for producing a rubber crawler according to 1. The method for producing a rubber crawler according to claim 1 , wherein the pre-press molding is performed at a temperature lower than the vulcanization temperature .

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