JP2001038818A - Production of rubber crawler and vulcanization mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent not only the ply separation and omission of rubber of a rubber article or a reinforcing cord but also the generation of bare by enhancing the bonding strength of the constituent parts of an endless bonded part of strip-like rubber. SOLUTION: Strip-like rubber 1 having reinforcing cords 8 embedded therein is constituted by one vulcanization molding and the both end parts 9 thereof are superposed one upon another to be bonded to produce a rubber crawler. In this case, both end parts 9 of the strip-like rubber 1 are molded in an unvulacanized or semi-vulcanized state and the addition vol. of both end parts 9 is made larger than required vol. after vulcanization bonding.

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 a rubber crawler used in agricultural machines, construction vehicles, snow vehicles, snow vehicles obtained by remodeling recreational vehicles, and vulcanized metal molds thereof. It is about type.

[0002]

2. Description of the Related Art For example, in manufacturing a rubber crawler by endlessly overlapping and joining a belt-like rubber having a reinforcing cord embedded therein, FIG. 7A shows a schematic cross-sectional view along the length direction. And a pair of upper and lower molds 101 and 102
The rubber material is molded and vulcanized by pressurizing and heating the rubber material in the molding cavity 103 defined by the above, and the band-shaped rubber 104 manufactured in such a single vulcanization molding step is stepwise thinned. As shown in a schematic cross-sectional view in FIG. 7B, the both end portions thus formed are overlapped and joined by pressurizing and heating with a joining mold 105, and the belt-shaped rubber itself is joined to FIG. 8A. As shown in FIG.
06, a rubber block 104a sequentially added by repeating feed vulcanization molding a plurality of times from one end to the other end
The step-like thin portions at both ends of the belt-shaped rubber 104 are directly overlapped and joined by a joining mold 105 as shown in FIG. Have been done.

As in the latter case, the belt-like rubber 10
4 is formed by a plurality of feed vulcanization moldings, the endless joints thereof are formed, for example, as shown in FIG. 9, by reinforcing cords protruding from each end of the rubber band 104 and extending in the longitudinal direction thereof. Under the required overlapping posture of 104b, the unvulcanized inner peripheral surface member 107 and the outer peripheral surface member 108 which are separately molded or not molded are formed in the overlapping region.
Are further superimposed, and both of these members 1
07 and 108 can be indirectly performed by being integrated into the belt-shaped rubber 104 by vulcanization molding using a joining mold 109.

In manufacturing a crawler comprising an endless rubber ring having a reinforcing cord embedded therein, a state in which a plurality of aligned reinforcing cords are connected endlessly in advance or one reinforcing cord is spirally formed. Under the wound state, as shown in FIG. 10, for example, based on repetition of feed vulcanization molding of the mold 110 along the reinforcing cord 111 thereof, each of the rubber blocks 112 is mutually vulcanized. It is known that they are sequentially added by sulfuric bonding to finally form an endless structure.

[0005]

By the way, in such a manufacturing method, both end portions of the belt-shaped rubber 104 are connected to each other as shown in FIG.
As shown in FIG. 8 (b) and FIG. 8 (b), in the case of vulcanization joining by overlapping, both end portions of the belt-shaped rubber 104 are subjected to vulcanization molding of the rubber itself, in an unvulcanized or semi-vulcanized state. It is preferable to increase the adhesive strength between the end portions and between each end portion and the reinforcing cord,
This means that in indirect endless joining of the belt-shaped rubber 104 as shown in FIG. 9, both end portions of the belt-shaped rubber 104 are bonded to the inner peripheral member 107, the outer peripheral member 108, and the reinforcing cord 104b. It is the same as above.

When the belt-shaped rubber 104 and the endless rubber ring are formed by sequentially adding rubber blocks 104a and 112, respectively, as shown in FIGS. Block 10
4a, 112, the vulcanization molding of the rubber block,
It is also preferable to form the additional end portion of the next block in an unvulcanized or semi-vulcanized state, in order to increase the adhesive strength to each part.

However, in reality, in rubber crawlers manufactured in this way, separation between rubbery materials is still difficult.
In addition to peeling of rubbery material from the reinforcing cord, rubber chipping may occur, and a bear may occur on the molding surface.

An object of the present invention is to solve such a problem.
By further increasing the adhesive strength of each component at the endless joint of the band-shaped rubber, the additional joint of each rubber block, etc., the occurrence of delamination of rubber, reinforcing cords and the like, rubber chipping, etc., It is an object of the present invention to provide a method of manufacturing a rubber crawler and a vulcanization mold capable of preventing occurrence of bears.

[0009]

According to a method of manufacturing a rubber crawler of the present invention, a belt-like rubber having a reinforcing cord embedded therein is formed by one vulcanization molding, and both ends of the belt-like rubber are overlapped and joined. In manufacturing the rubber crawler, both ends of the belt-shaped rubber are molded in an unvulcanized or semi-vulcanized state, and the added volume of both ends is configured to be larger than the required volume after vulcanization bonding. is there.

In this method, substantially the entire end portion of the rubber band, which is subjected to vulcanization bonding by a bonding mold, is unvulcanized or semi-vulcanized when vulcanizing the rubber band itself. As described above, the end portions can be joined with high adhesive strength, and the added volume of both unvulcanized end portions and the like can be reduced by the required volume after vulcanization joining in the same region. When the end portions of the belt-shaped rubber are vulcanized and joined by a joining mold, a sufficiently large pressing force is applied to the end portions, and the rubber material can sufficiently flow in the cavity. As a result, the adhesive strength between the end portions of the belt-like rubber and between the rubber material of each end portion and the reinforcing cord is greatly increased, and the occurrence of delamination, chipping of the rubber, etc. during use of the rubber crawler. It would be effectively prevented,
In addition, the occurrence of bears on the crawler surface is also prevented.

The ratio of the added volume to the required volume after the vulcanization bonding is preferably more than 100% and not more than 120% per one pitch of the rubber track. That is, if it is 100% or less, it is impossible to generate a large pressing force at the time of vulcanization bonding, and if it exceeds 120%, the material yield is greatly reduced.

In another manufacturing method of the present invention, a belt-like rubber having a reinforcing cord embedded therein is constituted by a continuous body of a rubber block sequentially added by a plurality of feed vulcanization moldings from one end to the other end, In producing a rubber crawler by directly or indirectly endlessly joining both end portions of the belt-shaped rubber, a rubber block to be vulcanized and molded first,
Subsequently, the end portion on the connection side to the rubber block to be vulcanized and formed is, for example, over the range of one pitch of the crawler
In the previous vulcanization molding, it is molded in an unvulcanized or semi-vulcanized state, and at the same time, its end portion is configured to be larger than a predetermined volume for one crawler pitch after vulcanization molding. is there.

According to this, when the rubber blocks are sequentially added by repeating the vulcanization molding, the end portions of the rubber blocks which have been unvulcanized by the previous vulcanization molding are replaced by the normal state in the subsequent vulcanization molding step. The end portion is unvulcanized or semi-vulcanized by placing it in the mold cavity and applying the same pressure and heating to the end portion as the rubber material for forming the adjacent rubber block. The volume of the end portion is larger than the volume of the corresponding mold cavity portion, and based on being greatly compressed in vulcanization molding, the end portion of the previously vulcanized rubber block is later It can be firmly adhered to each layer of the vulcanized rubber block, thereby preventing the occurrence of bear, and also effectively removes rubber crawler interlayer delamination, rubber chipping, etc. To prevent Door can be.

Preferably, the end portion of the rubber block to be vulcanized first and last is formed in an unvulcanized or semi-vulcanized state at the endless joining side, and the two ends are added together. The volume is greater than the required volume after vulcanization, or the volume at each end thereof is greater than the required volume after vulcanization.

According to the former, a high adhesive force can be secured when the both ends of the band-shaped rubber are overlapped and joined as described above, and according to the latter, both ends of the band-shaped rubber are joined together. In addition to the case of direct butt joining, in the case of indirect joining by interposing unvulcanized rubber between both end portions, a large adhesive force can be exhibited for the same reason as described above. .

In the latter case, when a belt-shaped rubber is formed by one vulcanization molding, both end portions to be joined endlessly are molded in an unvulcanized or semi-vulcanized state, and the volume of each end portion is adjusted. The same applies to the case where is larger than the required volume after vulcanization molding.

In still another manufacturing method of the present invention, for example, a rubber crawler comprising an endless rubber ring embedded with an endlessly connected or spirally wound reinforcing cord is sequentially formed by feed vulcanization molding a plurality of times. In forming the endless structure of the rubber block to be added to the above, the end portion of the rubber block that is first vulcanized and formed on the connection side to the block that is subsequently vulcanized and formed is subjected to the above vulcanization and molding. At that time, molded in an unvulcanized or semi-vulcanized state,
The end portion is configured to have a volume larger than a predetermined volume after vulcanization molding, for example, more than 100% and 120% or less.

In this manufacturing method, the connection strength between the rubber blocks can be increased in the same manner as in the above case, whereby the occurrence of peeling between blocks, various kinds of interlayer peeling, and chipping of rubber can be sufficiently prevented. , Can also be prevented from occurring.

In this manufacturing method, with respect to the rubber block to be vulcanized first, the end portion opposite to the above-mentioned end portion is also formed in an unvulcanized or semi-vulcanized state. It is preferable to configure a larger volume than the required volume after vulcanization molding. According to this, the connection strength when the rubber block is integrally connected to the rubber block to be finally vulcanized is also greatly increased. be able to.

The vulcanization mold of the present invention comprises a pair of dies which are opposed to each other and define a molding cavity for a rubber material, and a plurality of rubber blocks are formed by repeating vulcanization molding a plurality of times. And a cooling means for suppressing the vulcanization of the rubber material is provided at at least one end portion, and the molding cavity portion corresponding to the end portion per unit length is provided. Volume
It is larger than similar volumes of other parts. According to this, at least one end portion is in an unvulcanized or semi-vulcanized state, and can constitute a rubber block having a larger volume than other vulcanized molded portions.

Here, the rubber block which is first vulcanized and formed is provided with cooling means for suppressing vulcanization of the rubber material at both ends, and a unit length of the molding cavity corresponding to each end. It is preferable to configure a vulcanization mold having a larger volume per contact than similar volumes of the other parts. According to this, both ends of the rubber block are in an unvulcanized or semi-vulcanized state. And a larger volume than other vulcanized molded parts.

Further, in such a vulcanization mold,
In the case where at least one end, for example, both ends are provided with a lip for restraining leakage of the rubber material, for example, in the vulcanization molding of the first rubber block, the reinforcement cord is allowed to pass through the molding cavity, The material yield can be advantageously improved.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a vulcanization mold used for carrying out one method according to the present invention. This is a relatively short band of rubber 1
Is manufactured by one vulcanization molding, and comprises an upper mold 3 and a lower mold 4 which are positioned opposite to each other to define a molding cavity 2 made of a rubber material.

Here, the upper and lower dies 3, 4 are:
It has a molding surface of the lug 5 located on the outer peripheral surface of the rubber track and a surface for receiving the core 6 located on the inner peripheral surface side of the rubber crawler or forming a driving projection. The molding cavity 2 defined by the molds 3 and 4 has a stepped cavity depth at both ends thereof for the endless joining of the end portions of the band-shaped rubber 1, and furthermore, the molding cavity 2 has a stepped shape. It has a volume reducing portion 7 reduced from the opposite side.

Thus, the band-like rubber 1 vulcanized and molded by such a vulcanization mold has therein at least one reinforcing cord 8 which extends in the longitudinal direction of the rubber band.
In addition, each of the upper and lower surfaces has an uneven portion having a shape and size as required, and a thin portion 9 for overlap joining at both ends. In addition, as shown in FIG. 2, the thin portions 9 are overlapped and arranged in an endless vulcanizing mold 10 when the belt-shaped rubber 1 is joined endlessly, and both of them are pressurized. By heating, it functions to realize vulcanized joining without thickness steps.

By the way, as shown in this figure, a water jacket 11 is provided at a portion of the vulcanization molding die which contributes to the formation of the thin portion 9, in other words, at a portion corresponding to the volume reducing portion 7. In the operation of the vulcanization molding die, both end portions of the die are used as the non-vulcanization molding region 12 and the remaining portion is used as the vulcanization molding region 13.

In addition, here, for example, by making the added volume of each volume reducing section 7 larger than the cavity volume of the corresponding portion of the endless vulcanizing die 10, the vulcanization molding of the band-shaped rubber 1 by the vulcanizing die is performed. In the vulcanization molding, the thin portions 9 formed by the respective volume reducing portions 7 are set in an unvulcanized or semi-vulcanized state, and the added volumes of the thin portions 9 are vulcanized and joined. Larger than the required volume.

Therefore, when the two thin portions 9 of the belt-shaped rubber 1 are vulcanized and joined by the endless vulcanizing mold 10, the thin portions 9 are smoothly plastically flowed under the action of a large pressing force. The thin-walled portion 9 can be firmly adhered to the reinforcing cord 8 and the like in addition to the respective portions of the belt-shaped rubber 1 facing the thin-walled portion 9 by causing the cross-linking reaction quickly and sufficiently. Thus, here, it is possible to sufficiently prevent various delaminations, rubber chipping, and the like from occurring in the vulcanized joint portion, and it is possible to effectively prevent the occurrence of bears. In FIG. 2, reference numeral 14 denotes a hot air or other heat medium jacket or heater provided in the mold.

FIG. 3 is a sectional view showing a vulcanization mold used for carrying out another method according to the present invention. This is because rubber strips 1a, 1b, 1c,... Which are sequentially added to a belt-shaped rubber 1 in which a reinforcing cord 8 is embedded are sequentially added based on repeated vulcanization molding of a vulcanization molding die a plurality of times. In this case, it is assumed that the rubber blocks are sequentially added to the left side of the figure.

The vulcanization mold having an upper mold 21 and a lower mold 22 is provided at a left end portion of the mold cavity 23 in the drawing.
A range corresponding to a molding region for one pitch of the belt-shaped rubber 1 is defined as a non-vulcanized molding region 25 provided with a water jacket 24, and the volume of the molding region for one pitch of the molding cavity 23 is changed to another region. It is increased in the range from more than 100% to 120% or less of the volume of the molding area for one pitch in the vulcanization molding area 26.

In this vulcanization mold, when the rubber block 1c is vulcanized under the action of the mold, one pitch of the left end portion of the rubber block 1c is molded in an unvulcanized or semi-vulcanized state. At the same time, the volume is larger than the required volume after vulcanization molding. So here,
In the subsequent vulcanization molding of the rubber block, one pitch of the left end portion of the rubber block 1c is shaded on the right end portion of the vulcanization molding area 26 of the vulcanization mold in the figure. The vulcanization molding of the next rubber block is performed with the position determined and arranged as shown in FIG.

According to this, the left end portion of the previously vulcanized rubber block 1c is greatly pressurized during the vulcanization molding of the next rubber block, whereby the rubber material smoothly plastically flows. Since the crosslinking reaction is performed quickly and sufficiently, the rubber block 1c is firmly adhered to the rubber block to be vulcanized and molded. Therefore, delamination at the joint between the rubber blocks, Rubber chipping, occurrence of bears, and the like are effectively prevented.

As shown in the figure, the rubber block 1a to be vulcanized first also corresponds to, for example, one pitch of the belt-shaped rubber 1 at the right end of the vulcanization mold. With a range of non-vulcanized molding areas,
It is preferable to use a cavity part volume in the non-vulcanization molding area which is larger than a similar cavity part volume in the vulcanization molding area 26. In the case where the end of 1a is directly vulcanized and joined to the rear end of a rubber block to be finally vulcanized and formed under a butt shape or the like to form an endless structure, both butt ends are sufficiently vulcanized. By pressing and sufficiently reacting, a strong endless joint can be realized.

This means that the end portions of the rubber blocks formed by the first and last vulcanization moldings are arranged at the overlapping end portions of the reinforcing cord 8 as shown in FIG. 4, for example. Indirect vulcanization bonding with an endless vulcanization mold 29 under the interposition of an unvulcanized inner peripheral surface member 27 and an unvulcanized outer peripheral member 28 before or after molding, and once The same applies to the endless vulcanization joining of both end portions of the belt-shaped rubber formed by the vulcanization molding as shown in FIG. 4, and the end portions of the respective rubber blocks are the respective unvulcanized members 27, 28. , The reinforcing cord 8 and the like.

FIG. 5 is a cross-sectional view showing a vulcanization molding die used for carrying out still another method according to the present invention. That is, the rubber blocks are sequentially formed along the reinforcing cords 8 and formed to be continuous with each other by a plurality of feed vulcanization moldings in a state where the reinforcing cords 8 are endlessly configured in advance. It is used in the case.

Here, the vulcanization mold for the rubber block to be vulcanized first is as shown in FIG.
At both ends, a non-vulcanized molding zone 31 having a water jacket 30 formed therebetween, and a vulcanized molding zone 32 therebetween.
, Each of the non-vulcanized molding area 31,
The volume per unit length of the cavity portion, for example, the volume per length corresponding to one pitch of the rubber block is larger than the similar volume of the vulcanization molding area 32.

Therefore, the rubber block 33 vulcanized and formed by the vulcanization mold is formed by unvulcanized or semi-vulcanized portions corresponding to one pitch on both right and left ends in the figure.
The portion corresponding to one pitch has a required volume after vulcanization molding, in other words, a volume larger than the volume of the portion corresponding to one pitch in the vulcanization molding region 32.

In such a vulcanization molding die, as shown in FIG. 6, one end of the vulcanization molding die is allowed to penetrate the reinforcing cord 8, but the rubber material in the cavity is not leaked during the pressure molding. It is preferable to provide the lip 34 for preventing the rubber material from being provided with excellent formability and fluidity of the rubber material under a high pressing force, and also to improve the material yield.

FIG. 5 (b) shows a vulcanization mold for forming the second and subsequent rubber blocks.
Only the left end of the figure is the non-vulcanized molding area 35,
The volume of the cavity portion in the non-vulcanization molding region is increased as described above, while the remaining portion including the right end portion in the figure is the vulcanization molding region 36. Therefore, the cavity portion corresponding to the right end portion of the drawing has a volume per unit length substantially the same as the volume per unit length of the cavity portion corresponding to the other vulcanization molding zone portions.

In the case where the second rubber block is vulcanized by such a vulcanization molding die, the left end portion of the rubber block 33 formed by the first vulcanization molding in the figure is shown in FIG. As shown by hatching, the vulcanization molding die is positioned at the right end, and the second rubber block is vulcanized.

According to this, the left end portion of the rubber block 33 formed first is pressed against the rubber block 33 and the constituent parts of the second rubber block with a large force under the action of a large pressing force. At the same time, the flow smoothly flows to the details of the cavities, and furthermore, the cross-linking reaction at the left end portion proceeds promptly and sufficiently, similar to that of the second rubber block.
The rubber block is firmly adhered to the second rubber block, so that there is no inconvenience such as delamination or rubber chipping at the joint portion between the two rubber blocks, and no bear is generated.

By the way, the thus formed second
A large volume of unvulcanized or semi-vulcanized part is formed at the left end of the second rubber block 37 under the action of the non-vulcanized molding area 35. The third and subsequent rubber blocks can be formed in the same manner as described above, and as a result, the adjacent rubber blocks are firmly connected to each other.

Incidentally, in this vulcanization molding die,
By providing the lip 34 as described above at the end on the side of the non-vulcanized molding area, the moldability, fluidity, leakage resistance, and the like of the rubber material can be improved.

FIG. 5 (c) shows a vulcanization mold used to form the final rubber block and to use the rubber block as an endless structure. Each of the left and right end portions has a cavity partial volume substantially equal to the other portions, similarly to the right end portion of the vulcanization mold shown in FIG. 5B.

According to such a vulcanization mold, a large-volume unvulcanized end portion of the rubber block formed by the immediately preceding vulcanization molding is attached to the right end portion of the vulcanization mold diagram. In addition, by performing vulcanization molding of the last rubber block in a state where similar large-volume unvulcanized end portions and the like of the rubber block 33 formed first are respectively positioned and arranged at the left end portion in the figure, The rubber block formed first and the rubber block formed first can be firmly connected to the last rubber block for the same reason as described above.

[0046]

As is apparent from the above description, according to the present invention, the contact side end portion of the belt-shaped rubber or the rubber block is vulcanized by molding each rubber block.
By molding in an unvulcanized or semi-vulcanized state, and increasing the volume of the end part by the required volume after vulcanization molding, the connecting side end part is firmly attached with high adhesion to the opposing side member etc. Since it can be joined, it is possible to sufficiently prevent the occurrence of peeling between rubbery materials, between rubbery material and the reinforcing cord, and the occurrence of chipping of rubber, and at the same time, the occurrence of bear on the molding surface. Can also be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a vulcanization mold used for carrying out a method according to the present invention.

FIG. 2 is a sectional view showing an endless vulcanizing mold.

FIG. 3 is a longitudinal sectional view showing an embodiment of a vulcanization molding die.

FIG. 4 is a cross-sectional view showing another endless vulcanization mold.

FIG. 5 is a longitudinal sectional view showing another embodiment of a vulcanization molding die.

FIG. 6 is a cross-sectional view illustrating an end lip of a vulcanization mold;

FIG. 7 is a cross-sectional view showing a conventional vulcanization mold and a joining mold.

FIG. 8 is a cross-sectional view showing another conventional vulcanization mold and a joining mold.

FIG. 9 is a cross-sectional view showing another joining mold.

FIG. 10 is a cross-sectional view showing another conventional vulcanization molding die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Belt rubber 1a, 1b, 1c, 33, 37 Rubber block 2,23 Mold cavity 3,21 Upper die 4,22 Lower die 5 Lug 6 Core metal 7 Volume reduction part 8 Reinforcement cord 9 Thin part 10 Endless vulcanization mold 11, 24, 30 Water jacket 12, 25, 31, 35 Non-vulcanized molding area 13, 26, 32, 36, 38 Vulcanized molding area 14 Heat medium jacket 34 Lip

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 08 B29L 31:00

Claims (10)

[Claims] 1. A belt rubber in which a reinforcing cord is embedded is formed by one vulcanization molding, and both ends of the rubber band are overlapped and joined to manufacture a rubber crawler. A method for producing a rubber crawler, comprising molding in a vulcanized or semi-vulcanized state, and making an added volume of both end portions larger than a required volume after vulcanization bonding. 2. A belt-like rubber having a reinforcing cord embedded therein is formed by one vulcanization molding, and both ends of the belt-like rubber are endlessly joined to produce a rubber crawler. A method of manufacturing a rubber crawler, comprising molding in a vulcanized or semi-vulcanized state, and configuring each end portion to have a volume larger than a required volume after vulcanization molding. 3. A belt-like rubber having a reinforcing cord embedded therein is constituted by a continuous body of rubber blocks sequentially added by a plurality of feed vulcanization moldings from one end to the other end. In manufacturing a rubber crawler by joining endlessly, the end of the rubber block that is first vulcanized and formed on the connection side to the rubber block that is subsequently vulcanized and molded is used during the previous vulcanization and molding. A method for producing a rubber crawler, comprising molding in an unvulcanized or semi-vulcanized state and having a volume larger than a required volume after vulcanization molding. 4. An endless joining side end portion of a rubber block to be vulcanized first and last is formed in an unvulcanized or semi-vulcanized state, and an added volume of both end portions is vulcanized. The method according to claim 2, wherein the volume is larger than a required volume after the joining. 5. An endless joining side end portion of a rubber block to be vulcanized and molded first and last is formed in an unvulcanized or semi-vulcanized state, and the volume of each end portion is vulcanized. 3. The method according to claim 2, wherein the volume is larger than a required volume after molding. 6. A rubber crawler comprising an endless rubber ring having a reinforcing cord embedded therein is constituted by an endless structure of a rubber block which is sequentially added by a plurality of feed vulcanization moldings, and is vulcanized first. The end of the rubber block on the connection side to the rubber block to be subsequently vulcanized is molded in an unvulcanized or semi-vulcanized state during the previous vulcanization molding, and the required A method for manufacturing a rubber crawler, characterized in that it is configured to be larger than the volume of the rubber track. 7. The rubber block which is vulcanized and molded first.
The method for producing a rubber crawler according to claim 5, wherein the other end portion is formed in an unvulcanized or semi-vulcanized state, and is configured to be larger than a required volume after vulcanization molding. 8. A plurality of rubber blocks which are opposed to each other and define a molding cavity of a rubber material, and a plurality of rubber blocks are formed by repeating vulcanization molding a plurality of times. In the vulcanization mold, at least one end portion is provided with cooling means for suppressing the vulcanization of the rubber material, and the volume per unit length of the molding cavity portion corresponding to the end portion is set to the other portion. A vulcanization mold having a larger volume than that of the above. 9. A cooling means for suppressing vulcanization of a rubber material is provided at both end portions, and the volume per unit length of a molding cavity portion corresponding to each end portion is made smaller than a similar volume of other portions. The vulcanization mold according to claim 7, which is enlarged. 10. The vulcanization mold according to claim 7, wherein at least one end is provided with a lip for restraining leakage of the rubber material.