JPH06156334A - High elasticity rubber crawler and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase the flexibility so as to make difficult a generation of interface removal and improve the transmitting efficiency of the driving force, in a crawler whose inner peripheral layer is formed of an urethane rubber, and whose outer peripheral layer is formed of a vulcanized rubber of natural rubber and the like, or an elastic substance with the same level of elasticity. CONSTITUTION:At the center in the width direction of the inner periphery side of a crawler main body R, engaging parts 1b and engaging holes with a driving wheel are provided alternately placing a specific interval, and projections 1a1, 1a2, 1a3, and 1a4 for guiding rollers are projected on both sides of the center of the inner periphery surface, while grounding lugs 2 are projected to the outer periphery surface, so as to form this rubber crawler. And the inner periphery layer 1 including the projections 1a1, 1a2, 1a3, and 1a4 is formed of a high rigidity urethane rubber, and the outer periphery layer 2 including the grounding lugs 2a is formed of a vulcanized rubber of natural rubber and the like, or an elastic substance of the same level. Furthermore, reinforcing cords are buried lining up in the roller peripheral direction, near the border surface between the inner peripheral layer 1 and the outer peripheral layer 2, at the positions at both sides of the engaging parts 1b and the engaging holes.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber crawler mounted on a mobile work machine, wherein the inner peripheral layer is made of highly rigid urethane rubber and the outer peripheral layer is made of natural rubber. The present invention relates to a high-elasticity rubber crawler formed of vulcanized rubber such as the above, and a manufacturing method thereof. 2. Description of the Related Art A conventional rubber crawler has a main body made of vulcanized rubber mainly composed of natural rubber. As shown in FIGS. 8A and 8B, a metallic cored bar 2'is provided with a rubber crawler main body 1 '. A large number of steel cords 3'are arranged on the ground side of both blades 2'b, 2'b so as to be embedded at regular intervals in the inner circumferential direction, and a cored bar is provided on the inner peripheral surface of the crawler body 1 '. The projections 2'a, 2'a are projected to be used for guiding the rolling wheels, and the grounding lug 1'a made of the above-mentioned vulcanized rubber is projected on the grounding surface. (2'c is an engaging portion with a drive wheel, H'is an engaging hole) [Problems to be Solved by the Invention] The rubber crawler has been recognized to have various advantages over the iron caterpillar, In particular, it has been widely used because the ground lug is made of rubber and does not damage the pavement surface. However, since many cores and steel cords are embedded in the crawler body to withstand a large driving force from the drive sprocket, the crawler becomes heavy, and the part where the cores are not embedded lacks rigidity, and thus the crawler is not. It is apt to come off, and since the protrusion for guiding the rolling wheels is not provided at this portion, the interval between the protrusions is widened and there is a problem of noise vibration due to the fall of the rolling wheels. On the other hand, a rubber crawler made entirely of urethane rubber has a high elasticity and a high rigidity, so it is considered to solve the above-mentioned drawbacks. Since it is difficult to bend, problems will occur in terms of winding and meshing with the drive sprocket. (B) Urethane rubber has good durability against compression strain, but poor durability against extension. Therefore, cracks and cut scratches generated in the part that is repeatedly stretched grow rapidly, exposing and damaging the reinforcing material inside the crawler body. (C) Urethane rubber on concrete road surface There are problems such as abrasion resistance and (d) urethane rubber is expensive. FIG. 9 shows a state in which the rubber crawler main body 1'bends toward the inner peripheral side because a large tension (abnormal tension) is applied to the rubber crawler (T 'in the figure is an idle wheel). Occurs when debris or foreign matter is caught in the drive wheels or idle wheels. In this case, stress concentrates on the steel cord 3'layer closest to the center. There is also a problem that the steel cord is cut off sequentially and instantaneously toward the width end. The present invention is intended to solve the above problems, and is characterized in that the drive wheels are provided at a constant interval in the widthwise center of the inner peripheral side of the crawler body. A rubber crawler in which engaging portions and engaging holes with and are alternately provided, and projections for guiding the rolling wheels on both sides of the center of the inner peripheral surface and grounding lugs on the outer peripheral surface are respectively projected, and the inner portion includes the projections. The peripheral layer is formed of high-rigidity urethane rubber, and the outer peripheral layer including the grounding lug is formed of vulcanized rubber such as natural rubber or an elastic body equivalent thereto, and both sides of the engaging portion and the engaging hole are formed. The reinforcing cords are aligned and buried in the crawler circumferential direction in the vicinity of the boundary surface between the inner peripheral layer and the outer peripheral layer at a location. In this case, by embedding and reinforcing the reinforcing core in the engaging portion, the engagement with the driving wheel can be ensured and the driving efficiency can be improved. Further, the protrusions provided on both sides of the center of the inner peripheral surface are arranged on both outsides of the root position of the engaging portion on one side, and on the outside sides of the engaging portion and the engaging hole on the other side. By providing such a structure, the top surfaces of the left and right protrusions are continuous in the crawler circumferential direction, and the rolling wheels do not fall. In the method for producing the rubber crawler of the present invention, first, the outer peripheral layer is molded by press vulcanization in the same manner as in the production of ordinary rubber crawlers, and then liquid urethane rubber is applied to the non-grounded lug side of the outer peripheral layer. The inner peripheral layer is formed by injection molding. In the rubber crawler according to the present invention, the crawler body is divided into an inner peripheral layer and an outer peripheral layer in the thickness direction thereof, and since the inner peripheral layer is made of high-rigidity urethane rubber, it includes the protrusion of the crawler body. The entire inner peripheral side is highly rigid, making it difficult for the crawler to come off, and since the outer peripheral layer is made of vulcanized rubber made of natural rubber or the like or an elastic body equivalent to this, The entire outer peripheral layer including the lugs becomes flexible and easily bends toward the inner peripheral side. On the other hand, since the reinforcing cords are aligned and buried in the circumferential direction in the vicinity of the boundary surface between the inner peripheral layer and the outer peripheral layer, the crawler body does not extend in the circumferential direction, and the driving force is smoothly transmitted. Since the inner peripheral side is compressed around the reinforcing cord in the winding portion with the drive wheels, the inner peripheral layer (urethane rubber) is slightly compressed and stretched. Therefore, the durability is good. In the above manufacturing method, the liquid urethane rubber is injected and molded on the grounding lug side of the preformed outer peripheral layer to form the inner peripheral layer. At the time of the injection, the liquid urethane rubber is formed on the surface of the outer peripheral layer. Since it sufficiently penetrates into the fine uneven surface and then hardens, the boundary surface is completely adhered and adhered, and the inner peripheral layer and the outer peripheral layer are firmly bonded and integrated. FIG. 1 illustrates an embodiment of the rubber crawler of the present invention, in which A and B are plan views of the outer peripheral side (grounding surface side) and the inner peripheral side, respectively, and FIG. 1B is a sectional view taken along the line X ₁ -X ₁ , FIG. 3 is a sectional view taken along the line X ₂ -X _{2 of} FIG. 1B, and FIGS. 4A and 4B are a side view and a sectional view taken along the center line of FIG. 1A, respectively. Is a rubber crawler body, 1 is an inner peripheral layer made of highly rigid urethane rubber, 2 is an outer peripheral layer made of vulcanized rubber mainly composed of natural rubber, and E is a side end portion of the inner peripheral surface of the crawler body R. In this embodiment, the both end portions E, E are made of the vulcanized rubber of the outer peripheral layer 2. Therefore, even if the side end portion E hits an obstacle, it is hard to be damaged. In FIGS. 1A and 1B, 1a ₁ , 1a ₂ ,
Reference numerals 1a ₃ and 1a ₄ are projections for guiding the rolling wheels provided on the inner peripheral layer, 1b is an engaging portion that engages with the bottom of the drive wheel, H is an engaging hole that engages with the tooth tip, and 2a is The ground lugs 2b projecting from the outer peripheral layer 2 are central lugs connecting the left and right ground lugs 2a, 2a (the central lug 2b is the backside position of the engaging portion 1a), and the inner peripheral surface is as shown in the figure. 1a _{1 on the} left side of the center of
And 1a ₂ are provided on both sides of the base position of the engaging portion 1b, and on the right side, the protrusions 1a ₃ and 1a ₄ are provided on the engaging portion 1b and the engaging hole H.
Are provided at the respective outer positions of the above, and the top surfaces of the left and right projections are continuous in the crawler circumferential direction. In the present invention, since the above-mentioned projection is made by projecting urethane rubber of the inner peripheral layer, it can be provided at any position of the inner peripheral layer 1 on the inner peripheral surface. In the figure, M is a strip-shaped reinforcing core for reinforcing the engaging portion 1b to ensure the engaging action with the drive wheel, and as shown in the figure, the reinforcing core. M (indicated by a dotted line) has a length longer than the engaging portion 1b and is projected and embedded on both sides. Therefore, the engaging portion 1b and the projections 1a ₁ , 1a ₂ and 1a _{3 on the} left and right thereof are provided. The range including the area is made into an integrated thick block 1c, and the ground lug 2a at the back side position thereof
And the central lug 2b, this portion is a portion that is hardly bent in the winding portion around the drive wheel and the idle wheel. On the other hand, between the protrusions 1a ₂ and 1a _{1 on} the left and right of the engagement hole H (interval P ₂ ) and between the protrusions 1a ₃ and 1a _{4 on the} right (interval P ₃ ).
Is made as thin as possible over the entire width of the crawler so as to be easily bent. Also, P ₂ > P ₁ (P ₁ is a thick block 1c
As a distance between the protrusions 1a ₁ and 1a ₂ ), the distance P ₂ between the thin-walled portions is made as wide as possible so that no distortion occurs in the winding portion. The material of the reinforcing core M is metal or high-strength plastic. 2B and 3, S ₁ and S ₂ are reinforcing cords embedded in the inner peripheral layer 1 and the outer peripheral layer 2, respectively, for preventing the rubber crawler from extending in the circumferential direction. As the cord S ₁ , high strength and high elastic modulus carbon fibers, aramid fibers, polyarylate fibers, and fiber cords such as nylon, polyester and vinylon, which have a slightly lower elastic modulus, can be impregnated into liquid urethane rubber. And the one with good adhesiveness is used, the reinforcement cord S
_{As 2,} there is used a brass-plated steel cord having good adhesion to vulcanized rubber. In the figure, K is a boundary surface between the inner and outer peripheral layers 1 and 1d is a ridge portion of the inner peripheral layer 1 slightly protruding toward the outer peripheral layer 2 and 2d is toward the inner peripheral layer 1 side. It is a ridge portion of the outer peripheral layer 2 that is slightly projected, and as shown in the figure, the reinforcing cords S ₁ and S
₂ are embedded in the ridges 1d and 2d near the boundary surface K, respectively, and are arranged in parallel at the same height inside the rubber crawler main body. For this reason, the inside of the rubber crawler main body at the winding portion around the drive wheel and the idle wheel is divided into the extension side and the compression side around the reinforcing cord layer, so that the winding state is relatively reasonable and the local portion Since large strain is not generated and internal fatigue is not accumulated, delamination of the boundary surface does not occur, resulting in excellent durability. Further, in this embodiment, a fibrous reinforcing cord is embedded near the center in the width direction and a steel cord is embedded outside, so that the abnormal tension is generated and the rubber crawler bends inward. At this time, the fibrous reinforcing cord near the center slightly extends, so that stress concentration does not occur in the reinforcing cord from the center, and the reinforcing cord is prevented from being cut. 5 to 7 are explanatory views of the manufacturing method of this embodiment, and FIG. 5A is a sectional view of the outer peripheral layer 2 (vulcanized rubber). The outer peripheral layer 2 is a conventional rubber crawler manufacturing. It is formed into an endless body by press vulcanization in the same manner as in the method. As shown in the figure, a reinforcing cord S ₂ (steel cord) is embedded in the ridge 2d, and a boundary surface K is formed. Has been treated with a primer and an adhesive. FIG. 5B is a cross-sectional view of the annular casting mold 3 (3a is an inner mold, 3b is an outer mold), and the outer peripheral surface of the inner mold 3a is fitted with the outer peripheral layer 2 and the recess Q is attached. ₂ , and a dent Q that becomes a space for forming the inner peripheral layer 1 on the inner peripheral surface of the outer mold 3b.
₁ are provided respectively, and both are assembled in a ring shape by mating with each other on the inner peripheral side and the outer peripheral side, and may be a split type having an appropriate size for convenience of the assembly. FIG. 6A shows the upper body in which the outer peripheral layer 2 is fitted in the recess Q ₂ of the inner mold 3a and is attached. As shown in the figure, the reinforcing cord S ₁ (fibrous reinforcing cord) is attached to the inner periphery. Wrap the layer 1 at a position to be the protruding portion 1d, and then engage the engaging portion 1
Both ends of the reinforcing core M are attached to the ridges 2d on both sides at the position of b with a urethane rubber adhesive to temporarily fix them. Instead of winding the reinforcing cord S ₁ , the urethane rubber ring body 4 as shown in FIG. 7 is prepared (the reinforcing cord S ₁ is embedded in the ring body 4 and the cross section and the circumferential length are ridges). The dimension is such that it can be suitably fitted into the portion to be the portion 1d), and this may be affixed to the protruding portion 1d and temporarily fixed. FIG. 6B shows a state in which the outer die 3b is attached to the outer periphery of the inner die 3a to which the outer peripheral layer 2 is attached (V is a liquid urethane rubber injection port), and in the figure, the outer die 3b is provided outside. Liquid urethane rubber is injected and cured from the injection port V into the formed space (recess Q ₁ ), and the molded rubber crawler is turned inside out to use the inner peripheral layer as the inner peripheral side and the outer peripheral layer as the outer peripheral side. To serve. In addition to the above method, it is possible to form the inner peripheral layer on the inner peripheral side of the outer peripheral layer. In this case,
(1) The outer mold has a recess for fitting and mounting the outer peripheral layer on the inner peripheral surface, whereas the inner mold has a recess for forming a space for forming the inner peripheral layer on the outer peripheral surface. (2) The outer peripheral layer is fitted into the recess of the outer mold to be attached, and then the reinforcing cord S ₁ or the ring body 4 is temporarily fixed to the surface of the outer peripheral layer at a location to be the protruding portion 1d. The reinforcement urethane M is placed and temporarily fixed in the same manner as in the above-mentioned method by injection molding of liquid urethane rubber. The present invention is not limited to the above embodiment, but the entire inner peripheral surface of the rubber crawler body may be constituted by an inner peripheral layer (urethane rubber), and a steel cord is embedded in the inner peripheral layer. The fibrous reinforcing cord may be embedded in the outer peripheral layer (vulcanized rubber). In this case, the steel cord should be given an appropriate surface treatment to improve its adhesion to urethane rubber. On the other hand, the fibrous reinforcing cord requires a surface treatment for improving the adhesion to rubber. Further, the reinforcing core M is not limited to a strip shape, and a plurality of steel cords, fibrous reinforcing cords and the like may be embedded in parallel. In the present invention, the outer peripheral layer 2 is formed of a vulcanized rubber such as natural rubber or an elastic body equivalent thereto,
That is, in addition to vulcanized rubber made of natural rubber or synthetic rubber, it may be made of thermoplastic elastomer or the like. In the rubber crawler of the present invention, since the inner peripheral layer 1 is made of high-rigidity urethane rubber, it is extremely excellent in preventing the crawler from coming off, and the outer peripheral layer 2 is a conventional rubber. Since it is made of the same vulcanized rubber as the crawler, the outer peripheral layer of the crawler body and the ground contact lug are flexible and easy to bend, so that they can be easily wound around the drive wheels and the pavement road surface is not damaged. Further, since the reinforcing cords are arranged in the circumferential direction in the vicinity of the boundary surface between the inner circumferential layer and the outer circumferential layer and buried in the circumferential direction, the crawler body does not extend in the circumferential direction and the driving force is smoothly transmitted. In addition, since the inner peripheral layer (urethane rubber) is not stretched due to only a slight compressive strain in the winding portion around the drive wheel, the durability of the inner peripheral layer is improved,
Further, since the boundary surface has almost no expansion and contraction and no distortion occurs, interface peeling or the like hardly occurs and the rubber crawler has excellent durability. In addition, according to the present invention, since the reinforcing core is embedded and reinforced at the engaging portion, the engagement with the drive wheel can be ensured and the transmission efficiency of the driving force can be improved. Since the top surfaces of the protrusions are arranged continuously in the crawler circumferential direction, the rolling wheel track is continuous, and the vibration noise during running can be made extremely small. Further, in the manufacturing method of the present invention, the liquid urethane rubber is injected into the surface of the preformed outer peripheral layer to form the inner peripheral layer, and the liquid urethane rubber is injected into the surface of the outer peripheral layer during the injection. As it hardens after sufficiently penetrating into the fine uneven surface of, the boundary surface between the inner and outer layers is completely adhered and adhered, and both layers are firmly joined and integrated to improve durability. It was able to be excellent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a rubber crawler of the present invention,
A and B are plan views of the outer peripheral side and the inner peripheral side, respectively. FIG. 2 is a sectional view taken along line X ₁ -X ₁ of FIG. 1B. 3 is a _X 2 -X ₂ line sectional view of FIG. 1B. 4A and 4B are a side view and a center line cross-sectional view of FIG. 1A, respectively. 5A and 5B are views for explaining the manufacturing method of the present embodiment, in which A is a cross-sectional view of a preliminarily molded outer peripheral layer, and B is a cross-sectional view of an annular casting die. 6A illustrates a state in which an outer peripheral layer is fitted in a recess of the inner mold of the casting mold of FIG. 5B and is attached, and B illustrates a state in which an outer mold is attached to the outer periphery of the inner mold of A. FIG. is there. FIG. 7 shows a ring body. FIG. 8 shows a conventional rubber crawler, where A is a sectional view and B is a plan view. FIG. 9 shows a state where abnormal tension is applied to a conventional rubber crawler. [Explanation of reference numerals] R rubber crawler main body 1 inner peripheral layer 1a ₁ , 1a ₂ , 1a ₃ , 1a ₄ protrusion 1b engagement portion 1c thick block 1d ridge portion 2 (of the inner peripheral layer) outer peripheral layer 2a ground lug 2b Central lug 2d Ridge portion 3 (of the outer peripheral layer) Casting mold 3a Inner die 3b Outer die 4 Ring body E side end M Reinforcement cores S ₁ and S ₂ Reinforcement cord V Injection port

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Claims (1)

Claim: What is claimed is: 1. An engaging portion and an engaging hole for driving wheels are alternately provided at regular intervals in the widthwise center of the inner peripheral side of the crawler main body, and the inner peripheral surface is rolled on both sides of the center. A rubber crawler in which a ring guide projection and a ground lug are respectively provided on the outer peripheral surface of the rubber crawler, the inner peripheral layer including the projection being made of high-rigidity urethane rubber, and the outer peripheral layer including the ground lug being made of natural rubber or the like. A reinforcing cord is formed of vulcanized rubber or an elastic body equivalent to this, and a reinforcing cord is provided in the crawler circumferential direction near the boundary surface between the inner peripheral layer and the outer peripheral layer at both sides of the engaging portion and the engaging hole. A high-elasticity rubber crawler characterized by being aligned and embedded in 2. The high-elasticity rubber crawler according to claim 1, wherein a reinforcing core is embedded in the engaging portion. 3. The high-elasticity rubber crawler according to claim 1, wherein the protrusions projecting on both sides of the center of the inner peripheral surface are arranged on both outer sides of the root position of the engaging portion on one side. A high-elasticity rubber crawler is provided on the other side at positions outside the engaging portion and the engaging hole, respectively. 4. An inner peripheral layer including angular protrusions protruding from the inner peripheral surface is made of high-rigidity urethane rubber, and an outer peripheral layer including ground lugs protruding from the outer peripheral surface is a vulcanized rubber such as natural rubber or the like. A method of manufacturing a highly elastic rubber crawler formed of an elastic body equivalent to this, wherein the outer peripheral layer is first molded by press vulcanization in the same manner as in the production of a normal rubber crawler, and then the non-grounded lug side of the outer peripheral layer. A method for producing a high-elasticity rubber crawler, which comprises injecting and molding liquid urethane rubber into an inner layer to form an inner peripheral layer.