Method for manufacturing rubber crawler and rubber crawler

Abstract

To provide a method for manufacturing a rubber crawler that can efficiently manufacture rubber crawlers of which appearance can be favorably maintained and uniformity is secured, and to provide a rubber crawler.SOLUTION: In a method for manufacturing a rubber crawler, sequentially executed are: a first step of placing a strip-shaped rubber body 10, having a thickness t greater than a belt-forming cavity thickness width Tb, into a belt-forming cavity 50B using an openable / closable mold 50 where protrusion-forming cavity opening widths Wr and Wg are smaller than a belt-forming cavity width Wb; a second step of closing the mold 50 so that the strip-shaped rubber body 10 blocks protrusion-forming cavity openings 50RGo and 50Go to seal protrusion-forming cavities 50R and 50G; and a third step of injecting rubber into the protrusion-forming cavities 50R and 50G to fill them. A rubber crawler has rubber injection marks 5t on the surfaces of rubber protrusions 5 and 6, and a rubber crawler has interfaces 11i and 12i bulging toward the rubber protrusions 5 and 6 between a belt 2 and the rubber protrusions 5 and 6.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a rubber crawler that uses an endless band-shaped rubber body that rotates, and a method for manufacturing the same. Common examples of rubber crawlers include rubber crawlers used in agricultural vehicles such as forming tractors and combine harvesters, or construction vehicles such as hydraulic excavators and bulldozers. [Background technology]

[0002] Generally, a rubber crawler has a belt made of rubber material formed into an endless belt as its main body, with multiple lugs protruding from the outer surface of the belt that comes into contact with the ground at regular intervals around the belt, and multiple guide protrusions, drive protrusions, etc. protruding from the inner surface of the belt at regular intervals around the belt.

[0003] Conventionally, rubber crawlers have typically been manufactured with rubber protrusions such as lugs and guide protrusions formed in advance, and then the rubber protrusions are set in a mold so that they come into contact with a strip of rubber material in which reinforcing material is embedded, and then vulcanization molding is carried out to produce rubber crawlers with protruding rubber protrusions formed on the belt. However, it was time-consuming to incorporate each rubber protrusion into a mold, and there was a temperature difference between the band-shaped rubber body and the pre-molded rubber protrusions, which took a long time to vulcanize, making it difficult to manufacture efficiently.

[0004] Therefore, the same applicant as the present application previously proposed a method for manufacturing a rubber crawler in which guide protrusions are formed by supplying and filling molten rubber material into multiple guide protrusion cavities arranged at intervals along the inner periphery of an annular mold (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-78358

[0006] The manufacturing method for rubber crawlers disclosed in Patent Document 1 involves sequentially stacking an inner rubber sheet that forms the inner wall of the crawler, an embedded member that forms a reinforcing layer, and an outer rubber sheet that forms the ground contact area between an inner mold and an outer mold that are configured in a ring shape, and then pressurizing and vulcanizing the resulting structure.In the inner mold, rubber material is supplied and filled into multiple cavities that are connected to the inner surface of the inner rubber and arranged at intervals around the inner mold, and the resulting structure is vulcanized to form protrusions (rubber protrusions) for drive protrusions that are integrated with the inner rubber sheet.

[0007] By injecting rubber material into multiple cavities, rubber protrusions that become one with the inner rubber sheet are formed, eliminating the need for assembling the rubber protrusions. Injecting molten rubber shortens the vulcanization time, enabling efficient manufacturing. Summary of the Invention [Problem to be solved by the invention]

[0008] However, since the inner surface of the inner rubber sheet blocks the opening of the cavity formed in the inner mold and rubber material is supplied and filled into the closed cavity, there is a risk that the pressure of the supplied rubber will press against the inner surface of the inner rubber sheet, which only blocks the opening of the cavity, causing a dent. If the depression on the inner surface of this inner rubber sheet becomes larger, the blockage of the cavity opening by the inner rubber sheet will break, creating a gap and allowing rubber to leak out of the cavity.When the rubber leaks out, there will be an insufficient amount of rubber to form the rubber protrusion, resulting in a poor appearance.

[0009] Furthermore, if the rubber supplied to the cavity presses against the inner surface of the inner rubber sheet, causing a depression, or if the rubber leaks out of the cavity, the rubber inside the rubber sheet will flow significantly, affecting the reinforcing layer embedded in the rubber sheet and causing disturbances in the embedded member, which may make it impossible to ensure uniformity. If uniformity cannot be maintained, problems will arise with the rubber crawler's straightness, vibration, and durability, especially when traveling at high speeds.

[0010] The present invention has been made in view of the above points, and an object of the present invention is to provide a rubber crawler manufacturing method that can efficiently manufacture rubber crawlers that ensure good appearance and uniformity, and to provide such a rubber crawler. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides: A method for manufacturing a rubber crawler in which a belt made of a rubber material formed in an endless belt shape and having a reinforcing material embedded therein has a plurality of rubber protrusions arranged in the belt circumferential direction on at least one of the outer and inner peripheral surfaces, a belt-forming cavity for forming the belt and a protrusion-forming cavity for forming the rubber protrusions are arranged to overlap each other in the belt thickness direction, and a protrusion-forming cavity opening width in the belt width direction of the protrusion-forming cavity facing the belt-forming cavity is smaller than the belt-forming cavity width in the belt width direction of the belt-forming cavity, using an openable and closable mold; a first step of placing the belt-shaped rubber body, in which the reinforcing material is embedded, in the belt-forming cavity, the belt-shaped rubber body having a thickness greater than a belt-thickness width of the belt-forming cavity in the belt thickness direction of the belt-forming cavity; a second step of closing the mold to close the projection-forming cavity opening with the band-shaped rubber body, thereby sealing the projection-forming cavity; a third step of injecting rubber into the protrusion molding cavity to fill it; This is a method for manufacturing a rubber crawler, which sequentially carries out the steps above.

[0012] According to this configuration, a first step is carried out in which a strip of rubber having a thickness greater than the belt molding cavity thickness width is placed in the belt molding cavity using an openable mold whose protrusion molding cavity opening width is smaller than the belt molding cavity width, and then in a second step the mold is closed and the strip of rubber blocks the protrusion molding cavity opening, sealing the protrusion molding cavity.The strip of rubber having a thickness greater than the belt molding cavity thickness width blocks the protrusion molding cavity opening, and the surrounding part of the strip of rubber facing the protrusion molding cavity opening is pressed and compressed to the belt molding cavity thickness width, the compressed rubber flows into the protrusion molding cavity, and the part of the strip of rubber facing the protrusion molding cavity opening bulges out so as to bite into the protrusion molding cavity opening, forming a bulge that is thicker than the strip of rubber and tightly seals the protrusion molding cavity.

[0013] Therefore, when rubber is injected and filled into the protrusion molding cavity in the third step, even if the pressure of the filled rubber presses against the bulging portion of the band-shaped rubber body that has bulged out and blocked the protrusion molding cavity opening, deformation of the bulging portion that has digged into the protrusion molding cavity opening is suppressed. By suppressing deformation of the bulging portion that bulges into the protrusion molding cavity, it is possible to prevent gaps from forming when the band-shaped rubber body closes the protrusion molding cavity, which would allow the rubber to leak out of the protrusion molding cavity.

[0014] Since the rubber does not flow out of the protrusion molding cavity, there is no risk of an insufficient amount of rubber forming the rubber protrusions, which would cause poor appearance, and the appearance can be maintained in a good condition. Furthermore, by suppressing deformation of the bulging portion of the band-shaped rubber body that bulges into the protrusion molding cavity and by preventing rubber from leaking out of the protrusion molding cavity, the flow of rubber within the band-shaped rubber body is suppressed, thereby suppressing the impact on the reinforcing material embedded in the band-shaped rubber body and ensuring uniformity as a rubber crawler.

[0015] In a preferred embodiment of the present invention, After injecting and filling the protrusion molding cavity with rubber in the third step, a fourth step is carried out to vulcanize the rubber in the cavity of the mold.

[0016] According to this configuration, after the rubber is injected and filled into the protrusion molding cavity in the third step, the rubber in the mold cavity is vulcanized. Therefore, the rubber warmed by injection is vulcanized when it is filled into the protrusion molding cavity, thereby shortening the vulcanization time. Vulcanization strengthens the bond between the belt and the rubber projections, promoting greater integration.

[0017] In a preferred embodiment of the present invention, The belt-shaped rubber body has a convex portion formed on a peripheral surface thereof that faces the protrusion molding cavity in the thickness direction of the belt-shaped rubber body, When the band-shaped rubber body is placed in the belt-molding cavity in the first step, the protrusion faces a surface that is wider around the periphery than the opening of the protrusion-molding cavity.

[0018] According to this configuration, the convex portion formed on the peripheral surface of the band-shaped rubber body that faces the protrusion molding cavity in the thickness direction of the band-shaped rubber body faces an area that is wider around the protrusion molding cavity opening, and when the mold is closed in the second step, the convex portion of the band-shaped rubber body blocks the protrusion molding cavity opening and seals the protrusion molding cavity, so that the part around the part of the convex portion that faces the protrusion molding cavity opening is pressed and compressed, and the compressed rubber flows into the protrusion molding cavity, forming a larger bulge that bulges out so as to bite into the protrusion molding cavity opening, and thus sealing the protrusion molding cavity more tightly. Therefore, when rubber is injected and filled into the protrusion molding cavity in the third step, deformation of the large bulging portion is more suppressed, the rubber is more reliably prevented from leaking out of the protrusion molding cavity, and an insufficient amount of rubber to form the rubber protrusion is easily avoided, maintaining a good appearance of the rubber protrusion and easily ensuring uniformity as a rubber crawler.

[0019] The present invention provides In a rubber crawler having a plurality of rubber projections arranged in the circumferential direction of an endless belt on its peripheral surface, there are traces of rubber injection on the surface of the rubber projections.

[0020] According to this configuration, since there are rubber injection marks on the surface of the rubber projections of the rubber crawler, the rubber crawler is a rubber crawler manufactured with the rubber projections formed by injection molding.

[0021] The present invention provides In a rubber crawler having a plurality of rubber projections arranged in the circumferential direction of an endless belt on its peripheral surface, there is an interface between the belt and the rubber projections that bulges out toward the rubber projections.

[0022] According to this configuration, there is an interface between the belt and the rubber protrusions that bulges toward the rubber protrusions, and the rubber crawler is manufactured by pressing a rubber body against the opening of the protrusion molding cavity that forms the rubber protrusions and its surrounding area, forming a bulging portion that bulges out so that it bites into the protrusion molding cavity opening and sealing the protrusion molding cavity, and then injecting rubber into the protrusion molding cavity to form the rubber protrusions. [Effects of the Invention]

[0023] In this invention, an openable mold is used, in which the width of the protrusion-forming cavity opening is smaller than the width of the belt-forming cavity, and a strip-shaped rubber body having a thickness t greater than the belt-forming cavity thickness width Tb is placed into the open mold in a first step. Then, in a second step, the mold is closed and the strip-shaped rubber body presses against the protrusion-forming cavity opening to close it and seal the protrusion-forming cavity. When the strip-shaped rubber body having a thickness greater than the belt-forming cavity thickness width is pressed against the protrusion-forming cavity opening to close the opening, rubber flows into the protrusion-forming cavity and forms a bulge that digs into the protrusion-forming cavity opening, tightly sealing the protrusion-forming cavity.

[0024] Therefore, when rubber is injected into the protrusion molding cavity to fill it, even if the pressure of the filled rubber is applied, deformation of the bulging portion that digs into the protrusion molding cavity opening is suppressed, and the rubber is prevented from leaking out of the protrusion molding cavity.This means that the appearance can be maintained in a good condition, the flow of rubber within the band-shaped rubber body is suppressed, and the impact on the reinforcing material embedded in the band-shaped rubber body is also suppressed, ensuring the uniformity of the rubber crawler. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a perspective view showing, in partial cross section, a rubber crawler track according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view showing the outer circumferential surface of the rubber crawler track. [Figure 3] 3 is a cross-sectional view of the rubber crawler taken along the line III-III in FIG. 2. [Figure 4] FIG. 2 is a side view schematically showing a closed state of a mold used in the manufacturing method according to the present embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the mold as viewed from the arrows VV in FIG. 4. [Figure 6] FIG. 2 is a cross-sectional view schematically showing the state in which the outer mold and inner mold of the mold are separated and a band-shaped rubber body is placed between them. [Figure 7] FIG. 2 is a cross-sectional view schematically showing a state in which a band-shaped rubber body is placed in the inner mold of the mold. [Figure 8] FIG. 2 is a cross-sectional view showing a schematic view of the outer and inner dies of the mold in a closed state with a band-shaped rubber body sandwiched between them. [Figure 9] FIG. 2 is a cross-sectional view schematically showing a mold immediately after injection molding and a molded rubber crawler track. DETAILED DESCRIPTION OF THE INVENTION

[0026] An embodiment of the present invention will be described below with reference to FIGS. The rubber crawler 1 according to this embodiment is used in a crawler traveling device of a combine harvester, which is an agricultural vehicle. A pair of travel devices are provided on the left and right sides of the vehicle, and can be driven independently of each other to allow the vehicle to travel freely.

[0027] The rubber crawler 1 is a circular, endless band-like rubber body that is stretched between the drive wheel and driven wheel of a crawler running device (not shown), and multiple rollers are arranged to roll on the inner surface of the part of the rubber crawler 1 that comes into contact with the ground. The traveling device can make the vehicle travel by rotating the rubber crawler 1 through the driving of the drive wheels.

[0028] FIG. 1 is a perspective view showing a rubber crawler 1 in partial cross section. Referring to Figure 1, the rubber crawler 1 has a main body made of a belt 2 made of rubber and formed in an endless belt shape, and the outer surface of the belt 2 that comes into contact with the ground has a plurality of lugs 5, which are rubber protrusions, protruding from it at regular intervals around the belt, and the inner surface of the belt 2 has a plurality of guide protrusions 6, which are rubber protrusions, protruding from it at regular intervals around the belt.

[0029] The lugs 5 protruding from the outer peripheral surface of the belt 2 of the rubber crawler 1 enable it to run on uneven ground, and the guide protrusions 6 protruding from the inner peripheral surface of the belt 2 guide the rollers in the belt width direction, preventing the rubber crawler 1 from coming off the rollers and therefore preventing it from coming off the driven wheels.

[0030] In the belt 2, a reinforcing material 3 consisting of a steel cord layer 3a and one or more reinforcing plies 3b is embedded continuously over the entire circumference of the belt. The steel cord layer 3a is made up of a plurality of steel cords extending parallel to the circumferential direction of the belt. The reinforcing ply 3b is disposed closer to the outer periphery of the belt than the steel cord layer 3a, and is a reinforcing layer in which a plurality of cords are arranged inclined or perpendicular to the circumferential direction of the belt.

[0031] Referring to FIG. 1, trapezoidal lugs 5 are formed on the outer peripheral surface of the belt 2 and arranged at regular intervals in the belt circumferential direction at the center of the belt width direction of the belt 2. Similarly, trapezoidal guide protrusions 6 are formed on the inner peripheral surface of the belt 2 and arranged at regular intervals in the belt circumferential direction at the center of the belt width direction of the belt 2.

[0032] Each of the lug 5 and the guide projection 6 has a rectangular top surface that is long in the belt width direction, and four isosceles trapezoidal side surfaces that are continuous with the four sides of the top surface. The lug 5 is larger than the guide protrusion 6 .

[0033] The mold 50 for vulcanizing and molding the rubber crawler track 1 has an annular shape as shown in FIG. The mold 10 can be opened and closed, and the outer mold 51 on the outer periphery side and the inner mold 52 on the inner periphery side are separated from each other to open and are brought into contact with each other to close. FIG. 4 is a side view showing the mold 50 in a state where the outer mold 51 and the inner mold 52 are joined together to close the mold 50. As shown in FIG.

[0034] Both the outer mold 51 and the inner mold 52 are divided into a plurality of segments in the circumferential direction, and the outer mold 51 and the inner mold 52 are combined to form the mold 50, and the outer mold 51 and the inner mold 52 are joined together to close the mold 50. The inner mold 52 does not have to be divided into segments.

[0035] FIG. 5 is a cross-sectional view of the mold 50 in a closed state as viewed from the arrows VV in FIG. When the mold 50 is closed, a belt-molding cavity 50B is formed within the mold 50 in a band-like shape that is continuous in the circumferential direction, and a plurality of lug-molding cavities 50R are formed on the outer periphery of the belt-molding cavity 50B at regular intervals in the circumferential direction, and a plurality of guide protrusion-molding cavities 50G are formed on the inner periphery of the belt-molding cavity 50B at regular intervals in the circumferential direction.

[0036] The belt molding cavity 50B is a space for molding the belt 2 of the rubber crawler 1, the lug molding cavity 50R is a space for molding the lugs 5, and the guide projection molding cavity 50G is a space for molding the guide projections 6. Therefore, the lug forming cavity 50R and the guide projection forming cavity 50G are positioned at the center in the belt width direction, and overlap with the belt forming cavity 50B in the belt thickness direction to form a common space.

[0037] Figure 6 is a cross-sectional view showing the state in which the mold 50 is open, with the outer mold 51 and the inner mold 52 facing each other and spaced apart, and showing a band-shaped rubber body 10, which will be described later, placed between the outer mold 51 and the inner mold 52. The dividing surface of the outer die 51 and the inner die 52 is a surface that divides the belt-forming cavity 50B formed in a belt-like ring shape into an outer peripheral side and an inner peripheral side.

[0038] That is, referring to Figure 6, the outer mold 51 has an outer belt molding cavity 50Bo that forms the outer peripheral side of the belt molding cavity 50B and a lug molding cavity 50R, and the inner mold 52 has an inner belt molding cavity 50Bi that forms the inner peripheral side of the belt molding cavity 50B and a guide protrusion molding cavity 50G.

[0039] As shown in FIG. 5, when the outer mold 51 and the inner mold 52 are mated to close the mold 50, the outer belt molding cavity 50Bo and the inner belt molding cavity 50Bi are mated to form the belt molding cavity 50B.

[0040] Referring to FIG. 5, the belt forming cavity 50B has a belt forming cavity width Wb, which is the width in the belt width direction, and a belt forming cavity thickness width Tb, which is the width in the belt thickness direction. The lug molding cavity 50R has a lug molding cavity opening 50Ro facing the belt molding cavity 50B, and the guide molding cavity 50G has a guide molding cavity opening 50Go facing the belt molding cavity 50B.

[0041] The belt forming cavity width Wb of the belt forming cavity 50B is larger than the lug forming cavity opening width Wr, which is the width of the lug forming cavity opening 50Ro in the belt width direction, and the guide forming cavity opening width Wg, which is the width of the guide forming cavity opening 50Go in the belt width direction. Furthermore, the lug molding cavity 50R has a larger capacity than the guide molding cavity 50G, and the lug molding cavity opening width Wr is larger than the guide molding cavity opening width Wg. Belt forming cavity width Wb >Lug molding cavity opening width Wr >Guide molding cavity opening width Wg

[0042] In addition, the outer mold 51 is formed with a runner 51r that runs from its outer peripheral surface to the bottom surface of the lug molding cavity 50R to guide the molten rubber into the lug molding cavity 50R, and the inner mold 52 is formed with a runner 52r that runs from its inner peripheral surface to the bottom surface of the guide protrusion molding cavity 50G to guide the molten rubber into the guide protrusion molding cavity 50G.

[0043] The belt-shaped rubber body 10 shown in FIG. 6 is a belt-shaped rubber body to be molded into the belt 2 by the belt molding cavity 50B of the mold 50, and has the reinforcing material 3 embedded therein. The belt-shaped rubber body 10 has a belt-shaped protrusion 10s formed in the center in the belt width direction on the outer peripheral surface facing the lug molding cavity 50R, the protrusion 10s continuing in a belt shape in the circumferential direction.

[0044] The width ws of the belt-like protrusion 10s in the belt width direction is larger than the lug-forming cavity opening width Wr and smaller than the belt-forming cavity width Wb. Lug forming cavity opening width Wr < belt-shaped convex portion width ws < belt forming cavity width Wb The circumferentially continuous band-like protrusion 10s has a band-like protrusion width ws greater than the lug molding cavity opening width Wr, so the band-like protrusion 10s faces a surface that is wider on the periphery than the lug molding cavity opening 50Ro.

[0045] The width w of the belt-shaped rubber body 10 in the belt width direction is approximately equal to the belt-forming cavity width Wb of the belt-forming cavity 50B. The thickness t of the belt-like rubber body 10 in the belt thickness direction on which the belt-like protrusions 10s are formed is greater than the belt-forming cavity thickness width Tb. Thickness of belt-shaped rubber body t>Thickness of belt molding cavity width Tb The belt-shaped protrusions 10s are thin, and the thickness of the belt-shaped rubber body 10 excluding the belt-shaped protrusions 10s is approximately equal to the belt molding cavity thickness width Tb.

[0046] A method for manufacturing the rubber crawler 1 using the mold 50 will be described below. In the first step, the band-shaped rubber body 10 is placed in an open mold 50 . As shown in FIG. 7, the belt-shaped rubber body 10 is arranged so as to fit into the inner peripheral belt-molding cavity 50Bi of the inner mold 52 in which the segments are joined together (first step).

[0047] The inner peripheral portion of the band-shaped rubber body 10 fits into the inner peripheral belt molding cavity 50Bi of the inner mold 52, and the inner peripheral surface of the band-shaped rubber body 10 contacts the bottom surface of the inner peripheral belt molding cavity 50Bi, blocking the guide molding cavity opening 50Go. In addition, if the inner mold 52 of the mold 50 is preheated from the first step, the temperature difference between the band-shaped rubber body 10 placed in the mold 50 and the molten rubber injected and filled therein will be smaller in the subsequent steps, which will contribute to shortening the vulcanization time.

[0048] Next, in the second step, the outer mold 51 is fitted to the inner mold 52 with the band-shaped rubber body 10 sandwiched therebetween, and the mold 50 is closed (see FIG. 8). Since the thickness t of the band-shaped rubber body 10 is greater than the belt molding cavity thickness width Tb, as shown in Figure 8, the band-shaped convex portion 10s on the outer surface of the band-shaped rubber body 10 comes into contact with the bottom surface of the outer peripheral belt molding cavity 50Bo of the outer mold 51, and the surrounding portion of the band-shaped convex portion 10s facing the lug molding cavity opening 50Ro is pressed and compressed to the belt molding cavity thickness width Tb, so that the compressed rubber easily flows into the lug molding cavity 50R and bulges out, biting into the lug molding cavity opening 50Ro, forming a large bulge portion 11 that is thicker than the band-shaped rubber thickness t, and tightly sealing the protrusion molding cavity 50R.

[0049] On the other hand, the inner surface of the strip-shaped rubber body 10 fitted into the inner belt molding cavity 50Bi of the inner mold 52 is also pressed against the bottom surface of the inner belt molding cavity 50Bi of the inner mold 52, and the strip-shaped rubber body 10 is pressed against the guide molding cavity opening 50Go to block the opening, and the surrounding portion of the strip-shaped rubber body 10 facing the guide molding cavity opening 50Go is pressed and compressed to the belt molding cavity thickness width Tb, and the compressed rubber flows into the guide molding cavity opening 50G and bulges out, biting into the guide molding cavity opening 50Go, forming a bulge portion 12 thicker than the strip-shaped rubber body thickness t, thereby sealing the guide molding cavity 50G.

[0050] In this way, the band-shaped rubber body 10 is sandwiched within the belt molding cavity 50B, and the inner mold 52 and outer mold 51 are aligned to close the mold 50. With the lug molding cavity 50R and the guide protrusion molding cavity 50G sealed by the band-shaped rubber body 10, the third step is carried out in which rubber is forcefully injected, i.e., injected, into the lug molding cavity 50R and the guide protrusion molding cavity 50G.

[0051] The molten rubber injected from the injection molding machine is guided to the lug molding cavity 50R by the runner 51r formed on the outer mold 51, and is injected into the lug molding cavity 50R through a gate opening at the bottom of the lug molding cavity 50R, filling the lug molding cavity 50R. Similarly, the molten rubber injected from the injection molding machine is guided to the guide protrusion molding cavity 50G by the runner 52r formed on the inner mold 52, injected into the guide protrusion molding cavity 50G through a gate opening at the bottom surface of the guide protrusion molding cavity 50G, and filled into the guide protrusion molding cavity 50G.

[0052] In the second step, as shown in Figure 8, the band-shaped rubber body 10 forms a bulging portion 11 that bulges out so as to bite into the lug molding cavity opening 50Ro, thereby sealing the lug molding cavity 50R, and also forms a bulging portion 12 that bulges out so as to bite into the guide molding cavity opening 50Go, thereby sealing the guide molding cavity 50G.

[0053] In this way, the band-shaped rubber body 10 forms bulges 11, 12 at the lug molding cavity opening 50Ro and the guide molding cavity opening 50Go, and the molten rubber is injected into the sealed lug molding cavity 50R and guide molding cavity 50G, guided by runners 51r, 52r, respectively, and fills the lug molding cavity 50R and guide molding cavity 50G, as shown in Figure 9 (third step).

[0054] Therefore, when rubber is injected and filled into the lug molding cavity 50R and the guide molding cavity 50G in the third step, even if the pressure of the injected and filled rubber presses against the bulging portions 11, 12 that have blocked the lug molding cavity opening 50Ro and the guide molding cavity opening 50Go, the bulging portions 11, 12 that have bulged out so as to bite into the lug molding cavity opening 50Ro and the guide molding cavity opening 50Go can withstand the pressing force and are not easily deformed (see Figure 9).

[0055] By suppressing deformation of the bulging portions 11, 12 that bulge into the lug molding cavity 50R and the guide molding cavity 50G, it is possible to prevent gaps from occurring when the band-shaped rubber body 10 blocks the lug molding cavity opening 50Ro and the guide molding cavity opening 50Go, which would cause the rubber to leak out of the lug molding cavity 50R and the guide molding cavity 50G.

[0056] Since the rubber does not flow out of the lug molding cavity 50R and the guide molding cavity 50G, there is no shortage of rubber to form the lug 5 or the guide protrusion 6, which causes poor appearance, and the appearance can be maintained in good condition.

[0057] In addition, by suppressing deformation of the bulging portions 11, 12 of the band-shaped rubber body that bulges into the lug molding cavity 50R and the guide molding cavity 50G, and by preventing rubber from leaking out of the lug molding cavity 50R and the guide molding cavity 50G, the flow of rubber within the band-shaped rubber body 10 is suppressed, reducing the impact on the reinforcing material 3 embedded in the band-shaped rubber body 10 and ensuring uniformity as a rubber crawler.

[0058] After the rubber is injected and filled into the lug molding cavity 50R and the guide molding cavity 50G, the rubber in the cavities of the mold 50 (belt molding cavity 50B, lug molding cavity 50R, guide molding cavity 50G) is vulcanized (fourth step). In the third step, the molten rubber is injected into the lug molding cavity 50R and the guide molding cavity 50G, so the temperature difference with the preheated band-shaped rubber body 10 is small, and the vulcanization time can be shortened. In the vulcanization-molded rubber crawler 1, the lugs 5 and guide projections 6 are bonded to the belt 2 in a stronger manner, promoting greater integration.

[0059] Since the rubber crawler 1 is manufactured as described above, the manufactured rubber crawler 1 has a good appearance, uniformity is ensured, and the vulcanization time is shortened, allowing for efficient manufacturing.

[0060] In this embodiment, the band-shaped rubber body 10 has a band-shaped protrusion 10s formed on the outer circumferential surface thereof facing the lug molding cavity 50R. Since the band-shaped convex portion 10s has a band-shaped convex portion width ws in the belt width direction that is larger than the lug molding cavity opening width Wr, the band-shaped convex portion 10s faces a surface that is wider around the periphery than the lug molding cavity opening 50Ro, and in the second step of closing the mold 50, the band-shaped convex portion 10s of the band-shaped rubber body 10 blocks the lug molding cavity opening 50Ro and seals the lug molding cavity 50R, so that the surrounding area of ​​the part of the band-shaped convex portion 10s that faces the lug molding cavity opening 50Ro is pressed and compressed, and the compressed rubber easily flows into the lug molding cavity 50R, and a large bulge portion 11 is formed that bulges out so as to bite into the protrusion molding cavity opening 50Ro, tightly sealing the protrusion molding cavity 50R.

[0061] Therefore, when rubber is injected and filled into the lug molding cavity 50R in the third step, deformation of the large bulging portion 11 is more suppressed, and the rubber is more reliably prevented from leaking out of the lug molding cavity 50R, maintaining a good appearance of the lug 5 and easily ensuring uniformity as a rubber crawler.

[0062] In addition, the band-shaped rubber body 10 has a band-shaped convex portion 10s formed on the outer peripheral surface facing the lug molding cavity 50R, but no band-shaped convex portion is formed on the inner peripheral surface facing the guide protrusion molding cavity 50G. This is because the guide protrusion molding cavity 50G, which has a smaller capacity than the lug molding cavity 50R, also has a smaller guide molding cavity opening 50Go, and even if the bulge portion 12 that bulges out to fit into the guide molding cavity opening 50Go in the second step of closing the mold 50 is small, the guide protrusion molding cavity 50G is tightly sealed, and when rubber is injected and filled into the guide protrusion molding cavity 50G in the third step, deformation of the bulge portion 12 is appropriately suppressed, preventing the rubber from leaking out of the guide protrusion molding cavity 50G. Therefore, the belt-shaped convex portion may be formed on the belt-shaped rubber body according to the need such as the capacity of the protrusion molding cavity.

[0063] As described above, by the manufacturing method using the mold 50, a rubber crawler 1 is manufactured in which a plurality of lugs 5 are formed protruding from the outer surface of the belt 2 at regular intervals in the circumferential direction of the belt, and a plurality of guide protrusions 6 are formed protruding from the inner surface of the belt 2 at regular intervals in the circumferential direction of the belt.

[0064] The manufactured rubber crawler 1 has rubber injection marks 5t (see FIG. 2) on the surfaces of the lugs 5, in this embodiment on the top faces of the lugs 5 that protrude in a trapezoidal shape. This is because in the third step, the lug is injection molded by injecting and filling the lug molding cavity 50R with rubber, and a rubber injection mark (rubber injection mark) 5t is left at the gate of the runner 51r that guides the molten rubber into the lug molding cavity 50R.

[0065] Similarly, although not shown, there are rubber injection marks on the top surface of the guide projection 6. Therefore, if there are rubber injection marks on the surfaces of the lugs or guide projections of the rubber crawler, it can be determined that the lugs or guide projections were formed by injection molding. The rubber injection marks are not limited to the top surfaces of the trapezoidally protruding lugs and guide protrusions, but may also be formed on the side surfaces.

[0066] In the second step, a band-shaped rubber body 10 having a thickness t greater than the belt molding cavity thickness width Tb is sandwiched between the mold 50 and the mold is closed, so that the rubber of the band-shaped rubber body 10 forms a bulging portion 11 that bulges out so as to bite into the lug molding cavity opening 50Ro, and also forms a bulging portion 12 that bulges out so as to bite into the guide molding cavity opening 50Go.Then, in the third step, molten rubber is injected and filled into the lug molding cavity 50R to form the lug 5, and molten rubber is injected and filled into the guide protrusion molding cavity 50G to form the guide protrusion 6, thereby forming an interface 11i between the belt 2 and the lug 5 that bulges out toward the lug 5, and forming an interface 12i between the belt 2 and the guide protrusion 6 that bulges out toward the guide protrusion 6.

[0067] The interface 11i is the boundary surface between the rubber of the bulging portion 11 of the band-shaped rubber body 10 and the rubber injected into the lug molding cavity 50R. The interface 12i is the boundary surface between the rubber of the bulging portion 12 of the band-shaped rubber body 10 and the rubber injected into the guide protrusion molding cavity 50G.

[0068] Therefore, if there is a bulging interface between the rubber crawler belt and the rubber protrusions (lugs 5, guide protrusions 6) on the side of the rubber protrusions (lugs 5, guide protrusions 6), it can be determined that the rubber crawler was manufactured by sandwiching a band-shaped rubber body with a thickness t that is larger than the belt molding cavity thickness width Tb, closing the mold 50 (second step), and injecting rubber into the protrusion molding cavity to form the rubber protrusions (third step).

[0069] The above describes a rubber crawler manufacturing method and a rubber crawler according to one embodiment of the present invention, but the aspects of the present invention are not limited to the above embodiment and include various aspects that are implemented within the scope of the gist of the present invention.

[0070] In this embodiment, the cross-sectional view of the rubber crawler in Figure 3 is a cross-sectional view taken at a point where the lugs 5 and the guide protrusions 6 are located at the same position in the circumferential direction of the belt, and the lugs 5 and the guide protrusions 6 are not necessarily located at the same position in the circumferential direction of the belt. Therefore, although the cross-sectional views of the mold in Figures 5 to 9 show the lug molding cavity 50R and the guide protrusion molding cavity 50G, the lug molding cavity 50R and the guide protrusion molding cavity 50G are not necessarily located at the same position in the belt circumferential direction.

[0071] The rubber crawler in this embodiment has multiple rubber protrusions (lugs 5 and guide protrusions 6) arranged on both the outer and inner surfaces of the belt, but the present invention also includes a crawler in which multiple rubber protrusions are arranged on only one of the outer and inner surfaces of the belt.

[0072] The band-shaped rubber body 10 in this embodiment has a band-shaped convex portion 10s formed on its outer peripheral surface in a continuous band shape in the circumferential direction, but the convex portion does not have to be a band-shaped convex portion in the circumferential direction; it may be a convex portion that faces a surface that is wider outward than the protrusion molding cavity openings at locations on the peripheral surface of the band-shaped rubber body that face each of the multiple protrusion molding cavity openings, and a band-shaped rubber body on which such convex portions are formed is also included in the present invention.

[0073] The present invention maintains a good appearance and ensures uniformity as a rubber crawler, thereby resolving issues with the rubber crawler's straightness, vibration, and durability, particularly when traveling at high speeds, and enabling the rubber crawler to be used for a long period of time. [Explanation of symbols]

[0074] 1... rubber crawler, 2... belt, 3... reinforcing material, 3a... steel cord layer, 3b... reinforcing ply, 5... lug, 5t... rubber injection mark, 6... guide protrusion, 10...Band-shaped rubber body, 10s...Band-shaped convex part, 11...Bulging part, 11i...Interface, 12...Bulging part, 12i...Interface, 50...Mold, 50B...belt molding cavity, 50Bo...outer peripheral belt molding cavity, 50Bi...inner peripheral belt molding cavity, 50R...Lug molding cavity, 50Ro...Lug molding cavity opening, 50G... Guide protrusion molding cavity, 50Go... Guide molding cavity opening, 51...outer mold, 51r...runner, 52...inner mold, 52r...runner, Wb: Belt molding cavity width, Wr: Lug molding cavity opening width, Wg: Guide molding cavity opening width, w: Band-shaped rubber body width, ws: Band-shaped convex portion width, Tb...belt molding cavity thickness width, t...thickness of belt-shaped rubber body.

Claims

1. A method for manufacturing a rubber crawler in which a belt made of a rubber material formed in an endless belt shape and having a reinforcing material embedded therein has a plurality of rubber protrusions arranged in the belt circumferential direction on at least one of the outer and inner peripheral surfaces, a belt-forming cavity for forming the belt and a protrusion-forming cavity for forming the rubber protrusions are arranged to overlap each other in the belt thickness direction, and a protrusion-forming cavity opening width in the belt width direction of the protrusion-forming cavity facing the belt-forming cavity is smaller than the belt-forming cavity width in the belt width direction of the belt-forming cavity, using an openable and closable mold; a first step of placing the belt-shaped rubber body, in which the reinforcing material is embedded, in the belt-forming cavity, the belt-shaped rubber body having a thickness greater than a width of the belt-forming cavity in a belt thickness direction of the belt-forming cavity; a second step of closing the mold to close the opening of the protrusion-forming cavity with the band-shaped rubber body, thereby sealing the protrusion-forming cavity; a third step of injecting and filling the protrusion molding cavity with rubber; A method for manufacturing a rubber crawler, comprising the steps of:

2. 2. The method for manufacturing a rubber crawler according to claim 1, wherein after the third step, rubber is injected and filled into the protrusion molding cavity, a fourth step is carried out to vulcanize the rubber in the cavity of the mold.

3. The belt-shaped rubber body has a convex portion formed on a peripheral surface thereof that faces the protrusion molding cavity in the thickness direction of the belt-shaped rubber body, 3. The method for manufacturing a rubber crawler according to claim 1, wherein when the band-shaped rubber body is placed in the belt molding cavity in the first step, the convex portion faces a surface that is wider around the opening of the protrusion molding cavity.

4. In a rubber crawler in which a plurality of rubber protrusions are arranged in the circumferential direction of the belt on the peripheral surface of an endless belt, A rubber crawler characterized in that the surfaces of the rubber projections have traces of rubber injection.

5. In a rubber crawler in which a plurality of rubber protrusions are arranged in the circumferential direction of the belt on the peripheral surface of an endless belt, A rubber crawler characterized in that an interface between the belt and the rubber projections is formed so as to bulge toward the rubber projections.

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