JP2001001347A - Production of rubber crawler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable adoption of a relatively small mold although an endless reinforcing code can be adopted, to reduce the member of processes, and to obtain uniform strength characteristics on the circumference. SOLUTION: A primary vulcanization process in which between a middle mold 3 arranged on the inner circumferential side of a endless ring-shaped reinforcing cord 4 and upper and lower molds 1, 2 arranged above and under the outer circumferential side of the cord 4 respectively, inner circumferential side rubber portions 6A, 6B of the approximately half circumferential length of the cord 4 and grounding side rubber portions 5A, 5B are vulcanization- molded and a secondary vulcanization process in which, following the primary vulcanization process, the residual portions of the approximately half circumferential length 5C, 5D, 6C, 6D are vulcanization-molded are provided. In this way, the approximately half circumferential length portion of a rubber crawler can be vulcanization-molded at one stroke by relatively small upper, lower, and middle molds 1, 2, 3, and the vulcanization is completed by vulcanization- molding of two times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an endless rubber crawler to be mounted on a high-speed snowmobile such as an RV vehicle or a construction vehicle.

[0002]

2. Description of the Related Art In recent years, there has been an increasing number of cases in which ordinary driving wheels of a leisure RV are removed, and an endless track driving device including a plurality of sprockets and rolling wheels is mounted and used as a snowmobile or the like. . A crawler composed of an endless rubber belt or the like is attached to such an endless track driving device, and it is urgently necessary to cope with an increase in traveling speed with the attachment of the crawler to an RV vehicle. I have. Further, in addition to ordinary snowmobiles and the like, construction vehicles and the like in which rubber crawlers that reduce noise, vibration, and the like are mounted are required to cope with high-speed crawlers. Generally, a crawler mounted on such an endless track driving device is vulcanized and molded by a method as shown in FIGS.

FIG. 10 shows a basic manufacturing method. As shown in FIG. 10A, a crawler 31 made of rubber band or the like in which a reinforcing cord (not shown) is embedded is used.
As shown in (B), upper and lower molds (molds) 33, 3
2 and vulcanize the crawler 31 by heating and heating the upper and lower portions of the crawler 31 by further sandwiching and heating the outer and inner hot plates 34 and 35, as shown in FIG. 10 (C). Staggered ends 31 of crawler 31
A, 31B are polymerized to form upper and lower molds 33T for end joining,
Both ends are vulcanized and joined by the 32T and the inner and outer heating plates 35T and 34T to obtain an endless crawler product.

FIG. 11 shows a manufacturing method called feed vulcanization, which is used when vulcanizing a relatively long crawler. A crawler 31 made of a long band rubber or the like in which a reinforcing cord (not shown) is embedded as shown in FIG.
11B, the upper and lower dies 33T and 32T having a relatively short predetermined length as shown in FIG. 11B, and the upper and lower portions are further sandwiched by an outer heat plate 34T and an inner heat plate 35T. After heating, a predetermined length of the crawler 31 is vulcanized, and this is sequentially repeated to vulcanize the entire length of the crawler 31. Then, as shown in FIG. The parts 31A and 31B are superimposed to form upper and lower dies 33T and 32T and inner and outer heating plates 35T and 3T.
Both ends are vulcanized and joined by 4T to obtain an endless crawler product.

[0005]

However, in such a conventional manufacturing method, preliminary molding of the crawler is performed in advance in a separate step before vulcanization, and then the crawler is charged into the vulcanization step. In addition to the large size of the equipment for carrying in the vulcanization process, the production process also required a great deal of time. In particular, in the vulcanization method shown in FIG. 10 described above, the mold and the hot plate become longer, which requires an installation space for a large space, and further requires a joining vulcanization step for only the end portions. Also,
In the vulcanization method shown in FIG. 11, although the mold and the hot plate are miniaturized, it is necessary to repeat vulcanization several times to about 10 times for each predetermined length, which requires much more vulcanization time. In addition, in the vulcanization step, a bonding vulcanization step of only the end portion similar to the above was further required. Moreover, in these vulcanizing production methods, both ends of the belt-shaped crawler including the reinforcing cord must be vulcanized and joined, and the reinforcing cord is overlapped and thickened at the joining portion, resulting in a crawler circle. In addition to making it impossible to provide uniform properties on the circumference, it is troublesome to connect each end of the reinforcing cords that are buried side by side in the length direction, and it is continuous in reinforcing strength There was also a possibility that the properties could be cut off. Furthermore, it is almost impossible to embed a spiral reinforcing cord that enables uniform circumferential reinforcing strength. For this reason, the conventional vulcanization-based manufacturing method cannot cope with the high-speed rotation of the crawler accompanying the speeding-up of the vehicle.

Accordingly, the present invention solves the problems of the conventional method of manufacturing a rubber crawler and can adopt a relatively small mold while adopting an endless reinforcing cord, and the number of steps is small. It is an object of the present invention to provide a method for manufacturing a rubber crawler capable of obtaining circumferentially uniform strength characteristics.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method of manufacturing a rubber crawler in which rubber provided on the inner peripheral side and the ground side of an endless ring-shaped reinforcing cord is heated and vulcanized by using a mold. In between the middle die arranged on the inner peripheral side of the endless ring-shaped reinforcing cord and the upper die and the lower die arranged respectively on the upper and lower sides of the outer peripheral side of the reinforcing cord, a part corresponding to a substantially half circumferential length of the reinforcing cord is provided. It comprises a primary vulcanization step of simultaneously vulcanizing and molding the peripheral rubber and the grounding side rubber, and a secondary vulcanizing step of vulcanizing and molding the remaining substantially half circumference in a similar manner following this step. It is characterized by being performed. The present invention also provides
The vulcanization circumference in the first vulcanization step is larger than the vulcanization circumference in the second vulcanization step. Further, the present invention is characterized in that a driving projection rubber piece is set in advance in each of the driving projection forming grooves formed in the inner die by pre-pressing. Further, the present invention is characterized in that the prepress of at least one inner peripheral rubber to the inner mold is performed by pressing the driving projection rubber piece and the inner peripheral rubber piece by a plate-like body via a reinforcing cord. Things. Also, in the present invention, the preform is pressed by the plate-shaped body of the one inner peripheral side rubber, the middle mold is rotated by 180 ° to be turned upside down, and then the expansion members before and after the middle mold are extended to tension the reinforcing cord. By this, the other inner peripheral side rubber is pre-pressed to a medium size. Further, the present invention is characterized in that lug rubber pieces are set in advance in the respective lug forming grooves formed in the upper and lower molds by pre-pressing. The present invention also provides a vulcanizing step of at least a rubber part on a side to be vulcanized rubber before joining and vulcanizing a connection portion between a rubber part in the primary vulcanizing step and a rubber part in the secondary vulcanizing step. Before polymerizing the release sheet facing the connecting portion and having irregularities, and after vulcanizing the peeling sheet to form irregularities in the connecting portion, the rubber portion and the second portion in the first vulcanization step In the secondary vulcanization step, a connection portion with a rubber portion is bonded and vulcanized. Further, the present invention is characterized in that an adhesive sheet made of an adhesive rubber or the like is interposed between a connecting portion between the rubber portion in the first vulcanization step and the rubber portion in the second vulcanization step during the bonding vulcanization. It is assumed that. Further, the present invention is characterized in that the joint vulcanization is performed as bonding of rubber parts after vulcanization after the secondary vulcanization step. Further, the present invention is characterized in that the sulfur content of the adhesive sheet is larger than the sulfur content of the rubber portion in the first vulcanization step and the sulfur content of the rubber portion in the second vulcanization step. . Further, according to the present invention, the difference between the sulfur content of the adhesive sheet and the sulfur content of the rubber portion in the first vulcanization step and the sulfur content of the rubber portion in the second vulcanization step is in the range of 1 to 10 PHR. Are large, and these are the means for solving the problem.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 are diagrams showing one embodiment of the rubber crawler manufacturing method of the present invention, FIG. 1 is a schematic diagram showing a vulcanization molding process, FIG. 2 is a diagram showing a vulcanization molding die, and FIG. FIG. 4 is a side view showing a step of prepressing the inner peripheral rubber into a middle mold, FIG. 5 is a side view showing a step of turning the middle mold upside down, and FIG. FIG. 7 is a side view showing a prepress step of one inner peripheral side rubber, FIG. 7 is a side view showing a state in which an upper and lower mold containing prepressed ground rubber is set, and FIG. 8 is a vulcanized state in which the upper and lower molds are heated under pressure. FIG. A schematic diagram of the rubber crawler manufacturing method of the present invention is as shown in FIG. FIG.
As shown in (A), a reinforcing cord 4 wound in a spiral shape and formed into an endless ring shape (either rubberized or bare. In some cases, it may be joined. The rubber 6 and 5 attached to the inner peripheral side and the ground side of the conventional type having end portions may be vulcanized by pressurizing and heating them with the molds 1, 2 and 3. In the crawler manufacturing method, between the middle die 3 disposed on the inner peripheral side of the endless ring-shaped reinforcing cord 4 and the upper die 1 and the lower die 2 disposed on the outer peripheral side of the reinforcing cord 4 respectively, FIG. As shown in FIG. 1 (B), a first vulcanization step of simultaneously vulcanizing and molding the inner peripheral rubbers 6A and 6B and the ground rubbers 5A and 5B for approximately half the circumference of the reinforcing cord 4, Subsequently, as shown in FIG. Feed, then FIG. 1 (D)
As shown in the figure, similarly, inner peripheral rubbers 6C and 6D set on the inner peripheral side of the endless ring-shaped reinforcing cord 4 and grounding rubbers 5C and 5C set on the outer peripheral side of the reinforcing cord 4 are similarly provided.
And a second vulcanization step of simultaneously vulcanizing D with the upper, middle and lower dies 1, 3, and 2 to vulcanize and mold the remaining substantially half circumference.

At this time, preferably, the vulcanization circumference (the circumference of the crawler portion composed of the inner circumference rubbers 6A and 6B and the ground rubbers 5A and 5B) in the first vulcanization step is set to a second length. The vulcanization circumference in the next vulcanization step (the circumference of the crawler portion composed of the inner circumference rubbers 6C and 6D and the ground rubbers 5C and 5D) is made larger. In the example of FIG. 1, the vulcanization circumference in the primary vulcanization step is substantially equal to the vulcanization circumference in the secondary vulcanization step. Even when the circumference is large, the same set of upper, middle, lower, and upper parts can be obtained by appropriately controlling the temperature of the overlapping set portion of the rubber in the mold due to the difference in the vulcanization circumference during the second vulcanization step. Even if a mold is used, the adverse effects due to double vulcanization of the connection portion can be easily eliminated. With this configuration, it is possible to easily perform the processing of the rubber joint portion set in the first vulcanization step and the second vulcanization step in the secondary vulcanization step, and also to use the reinforcing cord. Which affects the vulcanization joining accuracy of the rubber part with respect to
The vulcanized portion in the first vulcanization step in which the rubber portion is vulcanized first can be lengthened, and a more stable and uniform rubber crawler can be obtained. The rubber joint formed by the first vulcanization step and the second vulcanization step is preferably configured to be joined by male and female wedge engagement.

FIG. 2 shows a mold for vulcanization molding.
As shown in FIG. 1A, a middle mold 3 and an upper mold 1 and a lower mold 2 which are arranged vertically with the middle mold 3 interposed therebetween. The upper mold 1 and the lower mold 2 have the same shape, and are viewed from the arrow A in FIG.
As clearly shown in FIG. 2 (B) and FIG. 2 (D) which are arrows, a large number of lug forming grooves 1 </ b> A and 2A is engraved. FIG. 2C is a view taken in the direction of arrow B in FIG.
As will be understood from the above, a large number of upper and lower drive projection forming grooves 3A and 3B are engraved along the upper and lower centers of the middle die 3. Further, a tension cylinder 7 is provided at the center of the middle die 3, and a pair of expandable and contractible expansion members 8 </ b> A and 8 </ b> B are provided before and after the tension cylinder 7.

FIG. 3 is an overall schematic view of a vulcanizer, in which a lower mold 2 is disposed on a lower vulcanizing table 10 fixed to a floor or the like.
The upper die 1 is disposed below the upper vulcanization table 9 that moves up and down with respect to the lower vulcanization table 10. On the other hand, the middle die 3 is disposed at an appropriate position on the movable trolley 11 that can move on the floor, and the middle dies 3 are moved to an appropriate position between the upper die 1 and the lower die 2 by the movement of the movable trolley 11. It is configured to be arranged. Note that FIG.
As shown in FIG.
Is configured to be able to be turned upside down about its center O. The upper vulcanizing table 9 and the lower vulcanizing table 10 are provided with a heating device, and by pressing the upper vulcanizing table 9 close to the lower vulcanizing table 10 to press the upper, middle and lower parts. Between the molds 1, 2, and 3, the inner peripheral rubber 6 and the ground rubber 5 are vulcanized and molded as if the reinforcing cord 4 is embedded.

FIGS. 4 to 8 correspond to FIGS.
It is a figure explaining the primary vulcanization process of (B). The secondary vulcanization step is the same as the primary vulcanization step, and a description thereof will be omitted. When moving from the state shown in FIG. 1B to the second vulcanization step shown in FIG. 1C, the rubber crawler semi-finished product is fed in the circumferential direction by an appropriate method such as human power or a crane or roller drive. Can be done. Hereinafter, the first vulcanization step will be described with reference to FIGS. 4 to 8. As shown on the right side of FIG.
As shown in FIG. 4, first, the inner mold 3 is placed in a single state before the device 1 is installed between the upper vulcanizing table 9 and the lower vulcanizing table 10.
Each of the upper drive projection forming grooves 3A formed in the upper part of the housing has a soft unvulcanized drive projection rubber piece 6A2 housed therein, and a portion excluding the drive projection formation grooves 3A (see FIG. 2C). ), The belt-shaped inner peripheral rubber piece 6A1 is placed. The upper inner peripheral rubber 6A is constituted by the driving protrusion rubber pieces 6A2 and the inner peripheral rubber pieces 6A1. Then, FIG.
As shown in (B), the upper inner peripheral rubber 6A is pressed by the plate-like body 12 from above through the reinforcing cord 4,
The driving projection rubber piece 6A2 and the inner peripheral rubber piece 6A1 are set in advance by prepress. Note that reference numerals 13A and 13A
B is a front and rear tightening tool, which holds a prepressed state when the middle mold 3 described later is inverted.

When the prepress of the upper inner peripheral rubber 6A is completed in this way, as shown in FIGS. 5 (A), 5 (B) and 5 (C), the middle mold 3 has a central portion O (see FIG. 3 (B)). And rotate it upside down. (For convenience, in FIG. 1, the position at the time of vulcanization of the inverted upper inner peripheral side rubber 6A and the like is drawn above.) As shown in FIG. A soft unvulcanized driving projection rubber piece 6B2 is accommodated in each lower driving projection forming groove 3B located on the upper side, and a band-shaped inner peripheral rubber piece 6B1 is provided in a portion excluding these driving projection forming grooves 3B. Place. The lower inner peripheral rubber 6B is constituted by the driving protrusion rubber piece 6B2 and the inner peripheral rubber piece 6B1. Next, as shown in FIG. 6B, the tension cylinder 7 installed at the center of the
And the reinforcing cord 4 is tensioned by the pressing members 8A and 8B at the front and rear ends, so that the lower inner rubber 6B, which is the other inner rubber, is formed into the lower drive projection forming groove 3B of the middle die 3. Is prepressed. Thus, even when the prepress plate 12 for the upper inner peripheral rubber 6A, which is located below the middle die 3, is removed, the inner peripheral rubber 6A does not come off.

Thus, the middle mold 3 in which the inner peripheral rubbers 6A and 6B are set on the inner peripheral side of the reinforcing cord 4 by pre-pressing, as shown in FIG. And the lower vulcanizing table 10. As shown in FIG. 7, each of the upper vulcanizing table 9 and the lower vulcanizing table 10 has a lug forming groove 1A,
An upper mold 1 and a lower mold 2 in which lug rubber pieces 5A2 and 5B2 are set in advance by prepressing by an appropriate method are arranged in A. Outer peripheral surface of reinforcing cord 4, upper mold 1 and lower mold 2
After the ground rubber pieces 5A1 and 5B1 of the belt-like body are set between them, as shown in FIG. 8, the upper mold 1 and the lower mold 2 are sandwiched between the middle mold 3 and the upper vulcanizer 9 and the lower vulcanizer. The table 10 is heated under pressure to perform vulcanization molding. When the primary vulcanization step is completed in this way, the upper vulcanization table 9 and the lower vulcanization table 10 are separated from each other, and the upper and lower dies 1, 2 and the middle die 3, although not shown in the drawings, are omitted. When released from the rubber crawler, the movable carriage 11 retreats from between the upper vulcanizing table 9 and the lower vulcanizing table 10, and at its working position, the rubber crawler is moved by an appropriate method such as human power or a crane or roller drive. The semi-finished product is fed out in the circumferential direction, is set at the position shown in FIG. 1 (C), and shifts to the second vulcanization step.

FIG. 9 is an explanatory view of a joint vulcanization mode at a connection portion between the first vulcanization step and the second vulcanization step. FIG.
1A to 1B in the first vulcanization step in the first vulcanization step, and the connecting portions which are the ends of the rubber portions 5A and 6A;
In the secondary vulcanization step leading to (D), the bonding and vulcanization of the rubber parts 5C and 6C with the connection part which is the end will be described as an example. As shown in FIG. Prior to the primary vulcanizing step of vulcanizing 6A, at least before the vulcanizing step of the rubber part on the side to be vulcanized rubber (rubber parts 5A and 6A to be vulcanized rubber by the primary vulcanizing step) The release sheets 14A and 14B having irregularities facing the connection portion are polymerized,
As shown in FIG. 9 (B), after vulcanization, the release sheet 1
After peeling 4A, 14B to form irregularities on the connection, the connection between the rubber parts 5A, 6A in the first vulcanization step and the rubber parts 5C, 6C in the second vulcanization step is joined and vulcanized. I did it. With this configuration, it is possible to easily apply irregularities to the connection portion of the rubber portion and improve the adhesion performance by using a common sheet-like material having irregularities on the surface such as ox canvas as a release sheet. Therefore, it is possible to omit a troublesome process such as a conventional work of buffing the surface of the bonding portion.

As shown in FIG. 9 (C), at the time of the joining vulcanization, the rubber portion 5 in the first vulcanization step is used.
A, 6A and rubber parts 5C, 6C in the second vulcanization step
An adhesive sheet 15A made of an adhesive rubber or the like between connecting portions with
FIG. 9 shows a case where these are joined and vulcanized by interposing 15B.
As shown in (D), through the vulcanization of the rubber portions 5C and 6C in the second vulcanization step, the adhesive sheets 15A and 15B, which are unvulcanized rubbers, are simultaneously vulcanized, and the first vulcanization step is performed. The rubber portions 5A and 6A can be satisfactorily connected to the rubber portions 5C and 6C in the second vulcanization step. Here, as shown in FIG.
Regarding 5B, the connection surfaces of the rubber parts 5A and 6A in the primary vulcanization step after vulcanization have fine irregularities, but the rubber parts 5C and 6C in the secondary vulcanization step are unvulcanized. When the connection surface is a flat surface as in the illustrated example, the rubber portion 5 in the adhesive sheets 15A and 15B is used.
The C and 6C sides may be formed with irregularities. Preferably, the sulfur content of the adhesive sheets 15A, 15B is larger than the sulfur content of the rubber parts 5A, 6A in the primary vulcanization step and the rubber parts 5C, 6C in the secondary vulcanization step. This is to effectively prevent a decrease in hardness (a decrease in adhesive strength) due to the transfer of sulfur from the unvulcanized side to the vulcanized side of the adhesive interface during vulcanization.

Then, the sulfur content of the adhesive sheets 15A and 15B and the rubber parts 5A and 6 in the first vulcanization step are determined.
The difference between the sulfur contents of the rubber portions 5C and 6C in the A and the secondary vulcanization steps is in the range of 1 to 10 PHR and the adhesive sheet is larger, so that the unvulcanized side of the adhesive interface at the time of joint vulcanization. From the sulfur side to the vulcanization side, which leads to a decrease in the elastic modulus and adhesive strength at the connection part due to the deficiency due to the sulfur transfer, or a decrease in the adhesive sheet due to an excessive amount of sulfur. It is intended to effectively prevent a decrease in the adhesive force due to a decrease in physical properties of the rubber.

[0018] It is also possible that the joint vulcanization is carried out as bonding of rubber parts after vulcanization after the secondary vulcanization step. That is, in this case,
After vulcanizing the rubber parts 5A and 6A in the first vulcanization step and then vulcanizing the rubber parts 5C and 6C in the second vulcanization step as shown in FIG. It is an example of joining and vulcanizing a part. Even in this case, as described above, when vulcanizing each rubber portion, the peeling sheet 14 is used to form unevenness on the connection surface by using the release sheet 14 to increase the adhesive force, or to bond the rubber sheet with an adhesive sheet 15 of an appropriate component. It can be configured to effectively prevent the strengthening of the force and the deterioration of the physical properties.

Although the embodiments of the present invention have been described in detail above, the shapes of the upper, lower, and middle dies, that is, the shapes of the rubber crawlers (if the core burring type is used, are included in the scope of the present invention). Drive projection forming grooves in a medium-sized die are provided in a plurality of rows, and the protrusions of the respective cores are mounted in the grooves and vulcanized, etc., and the type of reinforcing cord (endless shape by spiral winding, connecting portion with parallel cord) , Bias cords, rubberized rubber cords, etc.), shape, shape of the expansion member in the middle size, its expansion and contraction, and movement of the middle size (or the middle side is immovable, and the upper and lower sides are movable. Preset shapes of the inner peripheral rubber and the ground rubber, the connection shape of the connecting portion between the rubber portion in the first vulcanization step and the rubber portion in the second vulcanization step, and the like. It may be appropriately selected for engagement vulcanization forms and the like.

[0020]

As described above in detail, according to the present invention, the rubber attached to the inner peripheral side and the ground side of the endless ring-shaped reinforcing cord is pressurized and heated by a mold to vulcanize. In the method for manufacturing a rubber crawler, the middle of the endless ring-shaped reinforcing cord and the upper die and the lower die arranged on the upper and lower sides of the outer peripheral side of the reinforcing cord, respectively, the reinforcing cord substantially. A first vulcanizing step of simultaneously vulcanizing and molding the inner circumferential rubber and the ground side rubber for a half circumference; By comprising a vulcanization process, it is possible to vulcanize almost half the circumference of the rubber crawler at a time with a relatively small upper, lower and middle mold, and vulcanization is completed by two convenient vulcanization moldings.
In addition to achieving cost reduction by downsizing vulcanization equipment, the number of processes is small, spiral reinforcement cords can be embedded, and there are few connections by vulcanization bonding and uniform strength characteristics around the circumference. It is possible to provide a rubber crawler capable of coping with high-speed running. In addition, the first
If the vulcanization perimeter in the next vulcanization step is larger than the vulcanization perimeter in the second vulcanization step, the overlap setting in the first vulcanization step and the second vulcanization step is set. In addition to being able to easily carry out the processing of the rubber joint in the secondary vulcanization step, the primary vulcanization of the rubber portion first, which affects the vulcanization joining accuracy of the rubber portion with respect to the reinforcing cord, The vulcanization part by the sulfurization process can be taken longer,
A more stable and uniform rubber crawler is obtained.

Further, by setting the driving projection rubber pieces or lug rubber pieces in advance in the respective driving projection forming grooves formed in the inner mold or the respective lug forming grooves formed in the upper and lower molds by pre-pressing, the rubber is filled. Since the unvulcanized rubber pieces can be sufficiently filled in the mold even in a large volume portion, a high-quality rubber crawler can be obtained by stable vulcanization without fear of nests. Further, in the case where the prepress of at least one inner peripheral side rubber to the inner mold is performed by pressing the driving projection rubber piece and the inner peripheral rubber piece by a plate-like body via a reinforcing cord, a large number of driving projections are provided. Pre-pressing can be performed by pressing the rubber pieces at once and uniformly pressing the inner peripheral rubber pieces through the reinforcing cords, and the pre-press work can be performed efficiently and stably. In addition, while maintaining the prepress state of the one inner peripheral rubber plate-like body, the middle mold is rotated 180 ° to be turned upside down, and then the reinforcing cord is stretched by extending the front and rear expansion members of the middle mold. When the other inner circumferential rubber is pre-pressed to the middle size, the one inner circumferential rubber can be pre-pressed with high efficiency and stable by the plate-like body, and easily by the tension of the reinforcing cord due to the extension of the expanding member in the middle size. Since the other inner peripheral side rubber can be prepressed, the prepress work process can be simplified.

Before the joint vulcanization of the joint between the rubber portion in the first vulcanization step and the rubber portion in the second vulcanization step, at least the vulcanization step of the rubber part on the side to be vulcanized rubber is performed. Before polymerizing the release sheet facing the connecting portion and having irregularities, and after vulcanizing the peeling sheet to form irregularities in the connecting portion, the rubber portion and the second portion in the first vulcanization step In the case of joining and vulcanizing the connection portion with the rubber portion in the secondary vulcanization step, the connection portion of the rubber portion can be easily formed by using an ordinary sheet-like material having an uneven surface such as ox canvas as a release sheet. The adhesive performance can be improved by applying irregularities to the surface, so that it is possible to omit a troublesome process such as a conventional work of buffing the surface of the bonded portion. Further, when an adhesive sheet made of an adhesive rubber or the like is interposed between a connection portion between the rubber portion in the primary vulcanization step and the rubber portion in the secondary vulcanization step during the bonding vulcanization, the adhesive rubber or the like is used. At the time of vulcanization of the adhesive sheet made of, the adhesive rubber component is sufficiently spread over the large adhesive area formed by the unevenness on the connection surface, and a large adhesive force is secured.

Further, when the bonding and vulcanization is performed as bonding between rubber parts after vulcanization after the secondary vulcanization step, even if the bonding surfaces after vulcanization are bonded together,
Sufficient adhesive strength can be ensured by the presence of unevenness on the connection surface. Further, when the sulfur content of the adhesive sheet is larger than the sulfur content of the rubber portion in the first vulcanization step and the sulfur content of the rubber portion in the second vulcanization step, the adhesive interface at the time of vulcanization does not have It is possible to effectively prevent a decrease in hardness (a decrease in adhesive strength) due to the transfer of sulfur from the vulcanization side to the vulcanization side. Further, the difference between the sulfur content of the adhesive sheet and the sulfur content of the rubber portion in the primary vulcanization step and the rubber content in the secondary vulcanization step is in the range of 1 to 10 PHR,
When the size of the adhesive sheet is larger, the elastic modulus and the adhesive force at the connecting portion are reduced due to the deficiency due to sulfur transfer, or the physical properties of the rubber of the adhesive sheet are reduced due to the excessive amount of sulfur. Thus, the adhesive force is effectively prevented from being reduced. Thus, according to the present invention, there is provided a rubber crawler manufacturing method capable of adopting an endless reinforcing cord, employing a relatively small mold, reducing the number of steps, and obtaining uniform circumferential strength characteristics. Provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of a vulcanization molding step, showing one embodiment of a rubber crawler manufacturing method of the present invention.

FIG. 2 is a view of the same vulcanization molding die.

FIG. 3 is an overall schematic view of the same vulcanizer.

FIG. 4 is a side view showing a step of prepressing an inner peripheral rubber into a middle die.

FIG. 5 is a side view showing a step of turning the middle mold upside down.

FIG. 6 is a side view showing a pre-pressing step of the other inner circumferential rubber into the middle mold after the reversal.

FIG. 7 is a side view showing a state in which an upper and lower mold containing prepressed ground rubber is set.

FIG. 8 is a side view showing a vulcanized state in which the upper and lower dies are pressurized and heated.

FIG. 9 is an explanatory view of a joint vulcanization mode at a connection portion between a primary vulcanization step and a secondary vulcanization step.

FIG. 10 is a schematic view of a first conventional example showing a vulcanization molding step of a rubber crawler manufacturing method.

FIG. 11 is a schematic view of a second conventional example showing a vulcanization molding step of a rubber crawler manufacturing method.

[Explanation of symbols]

 Reference Signs List 1 upper die 1A lug forming groove 2 lower die 2A lug forming groove 3 middle die 3A upper driving protrusion forming groove 3B lower driving protrusion forming groove 4 reinforcing cord 5 grounding rubber 5A, 5C upper grounding rubber 5B, 5D lower grounding rubber 5A1 5B1 Ground rubber piece 5A2, 5B2 Lug rubber piece 6 Inner circumference rubber 6A, 6C Upper inner circumference rubber 6B, 6D Lower inner circumference rubber 6A1, 6B1 Inner circumference rubber piece 6A2, 6B2 Drive projection rubber piece 7 Tension cylinder 8 Extension Pressure member 8A Front expansion member 8B Rear expansion member 9 Upper vulcanizing table 10 Lower vulcanizing table 11 Moving carriage 12 Plate 13 Tightening tool 13A Front tightening tool 13A Rear tightening tool 14 Release sheet 15 Adhesive sheet O Medium Central part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 24 B29L 31:32 F term (Reference) 4F202 AA45 AD16 AG05 AG13 AG16 AH22 CA09 CB01 CB12 CN01 CN21 4F203 AA45 AD16 AG05 AG13 AG16 AH22 DA11 DB01 DC01 DE16 DK02 DL09 DN23

Claims (11)

[Claims] 1. A method for manufacturing a rubber crawler, wherein a rubber attached to an inner peripheral side and a ground side of an endless ring-shaped reinforcing cord is pressurized and heated by a mold to vulcanize the rubber. At the same time, the inner circumferential rubber and the ground rubber for approximately half the circumference of the reinforcing cord are simultaneously applied between the middle mold arranged on the inner circumferential side and the upper mold and the lower mold arranged above and below the outer circumferential side of the reinforcing cord. Manufacturing a rubber crawler, comprising: a primary vulcanization step of vulcanization molding; and a secondary vulcanization step of vulcanizing and molding the remaining approximately half circumference in a similar manner following the step. Method. 2. The method according to claim 1, wherein the vulcanization circumference in the first vulcanization step is larger than the vulcanization circumference in the second vulcanization step. . 3. The method for manufacturing a rubber crawler according to claim 1, wherein a driving projection rubber piece is set in advance in each of the driving projection forming grooves formed in the inner die by pre-pressing. 4. The pre-press of at least one inner peripheral rubber to the inner mold is performed by pressing a driving projection rubber piece and an inner peripheral rubber piece by a plate-like body via a reinforcing cord. The method for manufacturing a rubber crawler according to claim 3. 5. The middle mold is rotated by 180 ° to turn it upside down in the prepressed state by the one inner peripheral rubber plate-like body, and then the expansion cord members before and after the middle mold are extended to tension the reinforcing cord. The method for manufacturing a rubber crawler according to claim 4, wherein the other inner peripheral side rubber is prepressed to a middle size. 6. The rubber crawler manufacturing method according to claim 1, wherein a lug rubber piece is set in advance in each of the lug forming grooves formed in the upper and lower molds by a prepress. 7. A vulcanizing step of at least a rubber part on a side to be vulcanized rubber before joining and vulcanizing a connecting portion between a rubber part in the first vulcanizing step and a rubber part in the secondary vulcanizing step. Before polymerizing the release sheet facing the connecting portion and having irregularities, and after vulcanizing the peeling sheet to form irregularities in the connecting portion, the rubber portion and the second portion in the first vulcanization step 7. The method for producing a rubber crawler according to claim 1, wherein a connection portion with a rubber portion in the secondary vulcanization step is joined and vulcanized. 8. An adhesive sheet made of an adhesive rubber or the like is interposed between a connection portion between a rubber portion in the first vulcanization step and a rubber portion in the second vulcanization step during the joining vulcanization. The method for manufacturing a rubber crawler according to claim 7, wherein 9. The method for manufacturing a rubber crawler according to claim 7, wherein the joint vulcanization is performed as bonding of rubber parts after vulcanization after the secondary vulcanization step. 10. The sulfur content of the adhesive sheet is larger than the sulfur content of the rubber portion in the first vulcanization step and the sulfur content of the rubber portion in the second vulcanization step. Or the method for producing a rubber crawler according to 9. 11. The adhesive sheet according to claim 1, wherein the difference between the sulfur content of the adhesive sheet and the sulfur content of the rubber portion in the first vulcanization step and the sulfur content of the rubber portion in the second vulcanization step is 1 to 10 PHR. 9. The method according to claim 8, wherein
11. The method for producing a rubber crawler according to any one of claims 10 to 10.