JP2000210948A - Manufacture of rubber crawler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the ravelment of a steel cord and enhance the durability of a rubber crawler by introducing a protuberant rubber piece previously press- molded into a cavity, when an unvulcanized rubber member and the steel cord are lapped in the cavity and the rubber crawler is vulcanized and molded. SOLUTION: When an internal drive-type rubber crawler is manufactured, a bottom force 11 having a cavity (a) for forming the inner peripheral face of a rubber crawler and a cavity (b) for forming the protuberance of the rubber crawler and a top force 12 having a cavity (c) for forming the outer peripheral face of the rubber crawler and a cavity (d) for forming a lug, are superposed over each other to constitute a cavity for molding the rubber crawler. Next, a previously press-molded protuberant rubber piece 30 is set inside the cavity (b) and a rubber crawler inner face rubber 31, a coated rubber 33 in which a steel cord 32 is embedded, a rubber crawler outer face rubber 34 and a rubber 35 for a rubber lug are lapped over each other in that order, in the cavity for molding the rubber crawler. Further, both top and bottom forces 11, 12 are clamped to vulcanize and mold the rubber crawler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a rubber track, and more particularly to a method for producing an internally driven rubber track.

[0002]

2. Description of the Related Art A rubber crawler is roughly divided into two by a driving method, and a so-called internally driven rubber crawler is used when traveling at a relatively high speed. This inner drive type rubber crawler does not generally have a core metal buried in rubber, but steel cords are buried in a row in the longitudinal direction of an endless rubber crawler, and a driving force is applied to the inner peripheral surface. Protrusions for transmitting and preventing wheel removal are formed at a constant pitch, and lugs are formed on the outer peripheral surface.

In the manufacture of such a rubber crawler, the lower mold has a cavity (a) forming the inner peripheral surface of the rubber crawler and a cavity (b) forming projections at a constant pitch, and the other upper mold is formed. Has a cavity (c) forming the outer peripheral surface of the rubber track and a cavity (d) forming a lug. The unvulcanized rubber is filled into the cavity (A) formed by the upper and lower molds and vulcanized. At the time of the vulcanization, fluidity is added to the rubber, and the cavity (A) is completely filled. Will be done. As a result,
The steel cord stretched in the cavity (A) flows along with the flow of the rubber material, causing turbulence, and it is difficult to produce the steel cord as designed.

That is, since the rubber flow particularly in the cavity (A) flows into the cavity (b), the steel cord is drawn into the cavity (b) side. It will bend toward it. That is, the steel cord is not buried linearly in the longitudinal direction of the rubber, but is buried in a state of rising toward the protrusion. When this is viewed in the longitudinal direction of the rubber track, the steel cord is buried between the projection and the non-projection in a pulsating state.

[0005] Further, even when the rubber track is viewed from a plane, the steel cord cannot be held down due to the absence of the core metal, and a disturbance such as meandering in the width direction occurs. That is, a rubber crawler having no core metal does not block the flow of the steel cord at the time of molding, and the steel cord flows by the flow of the rubber in the cavity (A) by the upper and lower dies, and the same plane in the rubber is formed. Often there will be cases that are not buried above.

[0006] In particular, the engagement of the rubber crawler without a core bar with the sprocket greatly depends on the embedding position of the steel cord, the pitch accuracy of the projections, and the like, and as described above, the steel cord is also affected in the width direction of the rubber crawler. Further, if the turbulence also occurs in the longitudinal direction, a partial meshing failure occurs with the sprocket, which causes a power loss and a decrease in the durability of the rubber crawler.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a rubber crawler having no metal core, in which the steel cord is not disturbed and the steel cord is buried on substantially the same plane in the rubber, thereby reducing the power loss. It is an object of the present invention to provide a novel manufacturing method which prevents the rubber crawler from being damaged and improves the durability of the rubber crawler.

[0008]

The present invention adopts the following constitution in order to achieve the above object. That is,
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; a cavity (c) forming an outer peripheral surface of the rubber crawler; and a cavity forming a lug ( d) to form a rubber crawler molding cavity (A), and in this cavity (A), an unvulcanized rubber member and a steel cord constituting each part of the rubber crawler are laminated and vulcanized. A method of manufacturing a rubber crawler, comprising inserting a prepress-formed rubber piece into a cavity (b).

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, in general, when a rubber crawler is molded, a force is applied to a steel cord together with the flow of rubber in a cavity. In this case, the core metal blocks the flow of the steel cord, but in the internally driven rubber crawler without the core metal, there is nothing to prevent the disturbance of the steel cord, and the occurrence of disturbance is avoided. Absent.

[0010] The present invention has been made in consideration of this point, and in the production of a rubber crawler, since the steel cord is disturbed particularly corresponding to the protrusion, the rubber for forming the protrusion is used in advance. Pre-pressing is performed. More specifically, a pre-pressed protruding rubber piece is set in a cavity (b) of a lower mold and subjected to vulcanization molding of a rubber crawler. For this reason, the protruding rubber piece was not so fluid during the manufacturing process of the rubber crawler, so that the steel cord was not disturbed.

However, in order to obtain such a projection rubber piece, it is usually extruded as a long body having substantially the same shape as the outer shape of the projection in the front-rear direction of the rubber crawler. This is cut to obtain a projection material, or extruded as a long body having substantially the same shape as the outer shape of the projection in the width direction, and then cut as if the length of the projection is substantially the same as the left-right direction. Is set in a prepress mold, and prepressed to obtain a projection rubber piece. This prepress is performed under the conditions of rubber vulcanization. That is, when the prepressed protruding rubber piece is used for manufacturing a rubber crawler, it is prepressed to such an extent that the shape is not changed so much by vulcanization molding (pressing and heating). Therefore, at a temperature of 120 to 130 ° C. which is relatively lower than the vulcanization temperature or lower,
Pressing is performed for about 3 minutes. In some cases, a long body may be obtained by rubber extrusion, prepressed, 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 processed under the prepress conditions described above.

In the projection as a rubber crawler,
In order to increase wear resistance, for example, a nylon rod or the like may be embedded in the projection.In this case, a groove is formed in advance at the position where the rod is embedded during extrusion molding, and this is cut and pre-pressed. Sometimes, a rod is inserted into this groove, and if necessary, a rubber piece covering the rod is further stacked and prepressed to obtain a protruding rubber piece.

In the extrusion molding of the projection material, it is not always necessary to have a shape substantially conforming to the outer shape of the projection from the beginning of extrusion. The projection material may have substantially the same outer shape as that of the projection material. That is, an unvulcanized rubber material having a bending line is obtained, and then cut to substantially match the thickness of the projection,
A projection material may be obtained by bending along the bending line. In the case of a projection rubber piece in which a rod is embedded, a projection rubber piece can be obtained relatively easily by inserting the rod at the time of bending.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The rubber track of the present invention will be described below 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. A cavity (a) forming the inner peripheral surface of the rubber crawler and a cavity (b) for forming the projection are formed at a constant pitch in the lower mold 11. Have been. On the other hand, the upper mold 12 has a cavity (c) forming the outer peripheral surface of the rubber track and a cavity (d) forming a lug. An unvulcanized rubber and a steel cord are set in a cavity (A) formed by the upper and lower dies 11, 12 and vulcanized.

In the production of a conventional rubber crawler, an unvulcanized rubber for forming a projection, an unvulcanized rubber constituting an inner peripheral surface of a rubber crawler, a steel cord, and an outer peripheral surface of a rubber crawler are formed in a cavity (A). In the present invention, the unvulcanized rubber constituting the lug, the unvulcanized rubber constituting the lug, etc. are superposed and vulcanized and formed by pressurizing and heating. In order to prevent the fluidity of the vulcanized rubber at the time of vulcanization, a rubber crawler is manufactured by fitting a protruded rubber piece 30 into the cavity (b).

FIG. 2 shows a prepressed projection rubber piece 30.
It is a figure which shows the process of shape | molding. That is, the first step is a step of extruding the rubber material for projection 30A (unvulcanized rubber material) by extruding with a rubber extruder.
Is substantially the same as the outer shape of the protrusion of the rubber track in the front-rear direction 30a. Next, in a second step, the projection material 30B is cut by a length 30b that is substantially the same as the thickness of the projection. Then, in the third step, this is pre-pressed. The projection material 30B is set in the cavity (e) of the pre-press mold 40, and the pre-press is performed under the condition of 120 ° C. × 2 minutes to form the projection rubber piece. 30 is obtained. As described above, the obtained rubber projection piece 30 has been semi-vulcanized by the prepress, as described above, and has a property that does not relatively change its shape under vulcanization conditions. Note that 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 then the protrusion may be cut to have a thickness substantially equal to the thickness of the protrusion in the front-rear direction. .

A rubber crawler is manufactured by using the projection rubber piece 30. First, the projection rubber piece 3
0 is set in the cavity (b), and a rubber crawler inner rubber 31, a coated rubber 33 in which a steel cord 32 is embedded, a rubber crawler outer rubber 34, and a rubber lug rubber 35 (all of which are shown) are sequentially arranged in the cavity (A). (Unvulcanized rubber) are stacked, and the upper and lower dies 11, 12 are closed and vulcanized. Of course, in some cases, a fiber reinforcing layer (not shown) may be superimposed on the inside and / or outside of the coated rubber 33.

As described above, in the production of the rubber crawler of the present invention, the projection rubber piece 30 has almost no fluidity at the time of vulcanization molding, and therefore, the steel cord 32 does not have a structure waving on the projection rubber piece 30 side. Instead, it is buried linearly at a predetermined position of the rubber crawler.

When the rubber crawler is used for high-speed running, it is preferable that the rubber crawler be formed in a uniform endless shape. For example, the lower mold 11 has an endless structure, and a cavity (b) is formed in the center thereof with a constant pitch. The protruding rubber piece 30 is set in the cavity (b), and the steel cord 32 is continuously spirally wound on the cavities (a) and (b) of the lower mold 11, and then the upper mold 12 is closed and each part is closed. It is preferable to obtain the unvulcanized rubber integrally by vulcanization molding.

FIG. 3 is a cross-sectional view of the rubber crawler 1 obtained by the method of the present invention. Reference numeral 2 denotes a projection formed from the inner peripheral surface of the rubber crawler. Reference numeral 3 denotes a lug formed on the outer peripheral surface. is there. A steel cord 4 is embedded in the rubber crawler 1 in the longitudinal direction. In this example, nylon fiber layers 5 and 6 are embedded inside and outside the steel cord 4. In such a rubber crawler 1, the protrusion 2
Is made of a pre-pressed rubber piece 30 referred to in the present invention. Since the fluidity of the rubber piece 30 is suppressed during the vulcanization molding of the rubber crawler 1, the steel cord 4 flows to the protrusion 2 side. It is buried while maintaining a substantially straight state in the longitudinal direction without being buried.

In the case of an inner drive type rubber crawler, a sprocket or a roller (not shown) comes into contact with the left and right side surfaces of the projection, so that this surface often wears. For this reason, for example, a nylon rod may be buried in the left-right direction of the projection. In such a case, when extruding the rubber material for projection 30A, the base is changed and FIG.
As shown in the figure, a rubber material 30A for a projection is obtained having a shape having a groove 30c in the longitudinal direction, which 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. It is preferable that the projection material 30B be set in a prepress mold to perform a prepress process.

The protrusion rubber material 30A obtained by extrusion molding may not be cut into a shape substantially the same as the protrusion after extrusion molding. In some cases, the cut rubber material 30A may be bent. The shape may be substantially the same as the shape of the protrusion. For example, as shown in FIG. 5, the rubber material 30A extruded in four blocks by three lines 30f may be bent along each line 20f to have substantially the same shape as the projection as a whole. Of course,
It goes without saying that the same can be applied to the case where the rod is buried.

[0023]

According to the present invention, since the steel cord is disturbed particularly at the protruding portion when the rubber track is manufactured,
The rubber for forming the projections is pre-pressed in advance. For this reason, the rubber projection pieces are not so fluid during the rubber crawler manufacturing process, and the steel cord is not disturbed by the rubber flow.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a rubber track of the present invention.

FIG. 2 is a view showing a step of molding a protruding rubber piece.

FIG. 3 is a cross-sectional view of a rubber track obtained by the present invention.

FIG. 4 is a diagram showing a molding process of another example of the projection rubber piece.

FIG. 5 is a view showing a molding process of still another example of the projection rubber piece.

[Explanation of symbols]

 A: a cavity formed by the upper and lower molds; a: a cavity forming the inner peripheral surface of the rubber crawler; b: a cavity forming the protrusion of the rubber crawler; c) a cavity forming the outer peripheral surface of the rubber crawler; 1) Rubber crawler obtained by the present invention, 2) Projection, 3) Lug, 4) Steel cord, 5, 6 Fiber layer, 11) Lower mold, 12) Upper mold, 30突起 Pre-pressed rubber piece for protrusion, 30A ゴ ム Rubber material for extrusion formed by extrusion, 30B ‥ Protrusion material, 30c ‥ groove, 30d ‥ Rod, 31 ‥ Rubber inner surface rubber, 32 ‥ Steel cord, 33 ‥ Coated rubber, 34 ‥ Rubber Crawler outer rubber, 35mm rubber lug rubber, 40mm prepress mold.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B29K 105: 24 B29L 31:00 F term (Reference) 4F202 AA45 AD16 AD27 AD35 AG03 AH17 CA27 CB12 CB20 CK41 CQ01 4F203 AA45 AD16 AD27 AD35 AG03 AH17 DA11 DC01 DJ01 DL10 4F204 AA45 AD16 AD27 AD35 AG03 AH17 FA01 FB12 FB20 FG05 FN17

Claims (5)

[Claims] 1. A lower mold having a cavity (a) forming an inner peripheral surface of a rubber crawler and a cavity (b) forming a protrusion of the rubber crawler, a cavity (c) forming an outer peripheral surface of the rubber crawler, and a lug. Cavity (d) forming
A rubber crawler molding cavity (A) is formed by superimposing an upper mold having a rubber mold, and an unvulcanized rubber member and a steel cord constituting each part of the rubber crawler are superimposed and vulcanized in the cavity (A). Crawler manufacturing method,
A method for manufacturing a rubber crawler, comprising inserting a prepress-molded rubber piece into a cavity (b). 2. An unvulcanized rubber body in which the projection rubber piece substantially conforms to the outer shape of the projection is obtained by extrusion molding, and then is cut to substantially conform to the size of the projection to obtain a projection material, which is prepressed. The method for producing a rubber crawler according to claim 1, wherein 3. An unvulcanized rubber body having a projection rubber piece substantially matching the size of the projection and having a groove is obtained by extrusion molding.
2. The method according to claim 1, wherein the protrusion is cut to substantially match the thickness of the protrusion, and an abrasion preventing rod is fitted into the groove to obtain a protrusion material, which is prepressed. 4. A protruding rubber piece is obtained by extruding an unvulcanized rubber body provided with a bending line, then cutting it, bending it along the bending line to obtain a protruding material, and prepressing it. A method for producing a rubber crawler according to claim 1. 5. The method for producing a rubber crawler according to claim 1, wherein the pre-pressing is performed under the conditions of rubber vulcanization.