1 METHOD FOR JOINING CONVEYOR BELT TECHNICAL FIELD [0001] 5 The present invention relates to a method for joining a conveyor belt having a core body formed by laminating a plurality of canvas layers and more particularly relates to a method for joining a conveyor belt that can reduce the joining work time and increase the quality of the join at the end in the lengthwise direction of the conveyor belt. 10 BACKGROUND [0002] A conveyor belt with a canvas layer as a core body is provided in a tensioned state between a driving roller and a driven roller installed at front and 15 rear sections of a belt conveyor apparatus. Then, the conveyor belt is supported by a plurality of guide rollers arranged between the driving roller and the driven roller. In a case where the conveyor belt is damaged after being used for a certain time or during use, replacement work for the entire conveyor belt, or repair work where the damaged portion is cut out and a new 20 conveyor belt is joined at the end in the lengthwise direction of the belt main body has been performed (for example, refer to Patent Document 1). [0003] Such replacement work or repair work for a conveyor belt has been exclusively performed at the usage site of the conveyor belt. For example, for 25 joining the end in the lengthwise direction of a conveyor belt having a core body formed by laminating a plurality of canvas layers, there are the following work steps (1) to (5) of: (1) forming a marking-off line on a target portion of a belt main body in order to cut out the end in the lengthwise direction of the belt main body in a 30 stepped shape (stepwise shape); (2) performing work of cutting out a cover rubber along the marking-off line without unnecessarily scratching the canvas layer with a cutting tool (a knife, a cutter, or the like); (3) performing alignment whether or not the portions, which are formed 35 in a stepped shape, of the ends in the lengthwise direction of the belt main bodies to be joined match with each other; (4) performing surface finishing by buffing the surfaces of the portions formed in a stepped shape using a polisher or the like; and 2 (5) achieving a form in such a manner that adhesive is applied on the portions which have been subjected to the surface finishing described above; and the portions formed in a stepped shape are laminated so as to face each other, and vulcanizing and bonding the laminated portion while applying heat 5 and pressure using a vulcanization apparatus so as to join the laminated portion. In the conventional work steps described above, complicated joining work of peeling, one at a time, the cover rubber and the canvas layer of the end in the lengthwise direction of the belt main body is performed. Since there are also constraints in the usage site of the conveyor belt in terms of the work 10 space or the processing facilities, there are problems in that the joining work requires a particularly long time. [0004] In addition, during the joining work, the canvas layer may be unnecessarily scratched by a cutting tool or there may be defects such as a 15 position shift of the canvas layer. Therefore, to ensure the quality of the join of the conveyor belt, a worker carrying out the joining work needs to be highly skilled. PRIOR ART DOCUMENT 20 Patent Document [0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. S63-252814A 25 SUMMARY OF THE INVENTION Problem to be Solved by the Invention [0006] An object of the present invention is to provide a method for joining a conveyor belt with a canvas layer as a core body that can reduce joining work 30 time and increase quality of a join at the end in the lengthwise direction of the conveyor belt. MEANS TO SOLVE THE PROBLEM [0007] 35 A joining method for a conveyor belt of the present invention for achieving the object described above is a method for joining a conveyor belt having a core body formed by laminating a plurality of canvas layers. The method includes steps of: forming the core body of at least one end in a 3 lengthwise direction of a belt main body ahead of time in a stepped shape; covering the top of the core body formed in a stepped shape by a peeling member; and vulcanizing and molding the belt main body with a cover rubber laminated on the peeling member; when joining end in the lengthwise direction 5 of the belt main body, peeling off the peeling member so as to eliminate the cover rubber laminated on the peeling member and to expose the core body formed in a stepped shape which has been covered by the peeling member; laminating, on the exposed core body, an other core body formed in a stepped shape to be joined so that the other core body faces the exposed core body; and 10 vulcanizing and joining a portion where the core bodies are laminated on each other. [0008] Here, it is possible for an excess length portion of the belt main body to be left at a tip end side in the lengthwise direction of the belt main body 15 beyond a portion where the core body is formed ahead of time in a stepped shape. When joining the end in the lengthwise direction of the belt main body, it is possible for the belt main body to be pulled into a belt conveyor apparatus by grasping the excess length portion and for the excess length portion to be cut away after the pulling of the belt main body. It is also possible for the 20 core body of only one end in the lengthwise direction of the belt main body to be formed ahead of time in a stepped shape, for the top of the core body formed in a stepped shape to be covered by the peeling member, and for the belt main body to be vulcanized and molded with the cover rubber laminated on the peeling member. Alternatively, it is also possible for the core bodies of both 25 ends in the lengthwise direction of the belt main body to be formed ahead of time in a stepped shape, for the tops of the core bodies formed in a stepped shape to be covered by the peeling members, and for the belt main body to be vulcanized and molded with the cover rubbers laminated on the peeling members. The length of the canvas layer formed ahead of time in a stepped 30 shape is set to, for example, from 0.5 to 2.0 m. EFFECT OF THE INVENTION [0009] According to the present invention, since the core body of at least one 35 end in the lengthwise direction of the belt main body is formed ahead of time in a stepped shape, the top of the core body formed in the stepped shape is covered by the peeling member, and the belt main body is vulcanized and molded with the cover rubber laminated on the peeling member, it is possible to 4 prepare ahead of time a necessary conveyor belt (a belt main body) in a belt manufacturing factory or the like instead of the usage site of the conveyor belt. Then, when joining the end in the lengthwise direction of the belt main body, the peeling member is peeled off so as to eliminate the cover rubber laminated 5 on the peeling member and to expose the core body formed in a stepped shape which has been covered by the peeling member, the other core body formed in a stepped shape to be joined is laminated on the exposed core body so as to face the exposed core body, and a portion where the core bodies are laminated on each other is vulcanized and joined. Therefore, it is not necessary to 10 perform complicated joining work at the usage site of the conveyor belt as in the conventional art. [0010] Accordingly, it is possible to significantly reduce the joining work time at the end in the lengthwise direction of the conveyor belt compared to the 15 conventional methods. In addition, since it is possible to reduce variations in the quality of joins, generated depending on skills of workers performing the joining work, there is an advantage in improving the quality of the joins. BRIEF DESCRIPTION OF THE DRAWINGS 20 [0011] FIG. 1 is a schematic configuration diagram of a belt conveyor apparatus. FIG. 2 is a perspective explanatory diagram illustrating an end in a lengthwise direction of a belt main body formed using the present invention. FIG. 3 is an explanatory diagram illustrating, in a side view, the belt 25 main body before being pulled into the belt conveyor apparatus. FIG. 4 is an explanatory diagram illustrating, in a side view, a step of cutting away an excess length portion of the belt main body after being pulled into the belt conveyor apparatus and exposing a core body formed in a stepped shape. 30 FIG. 5 is an explanatory diagram illustrating, in a side view, a step of laminating core bodies formed in a stepped shape so that the core bodies are placed to face each other. FIG. 6 is an explanatory diagram illustrating, in a side view, a step of joining in a case where a core body of only one end in the lengthwise direction 35 of the belt main body is formed ahead of time in a stepped shape.
5 BEST MODE FOR CARRYING OUT THE INVENTION [0012] Below, description will be given of a method for joining a conveyor belt of the present invention based on embodiments illustrated in the diagrams. 5 [0013] As illustrated in FIG. 1, a conveyor belt (a belt main body 1) is provided in a tensioned state between a driving roller 2A and a driven roller 2B installed at the front and rear sections of a belt conveyor apparatus. The belt main body 1 is wound around the driving roller 2A and the driven roller 2B in 10 addition to a plurality of guide rollers 2C arranged between the driving roller 2A and the driven roller 2B. [0014] As illustrated in FIG. 2, the conveyor belt (the belt main body 1) which is the subject of the present invention is a conveyor belt having a core body la 15 formed by laminating a plurality of canvas layers lb. In this embodiment, the core body la is formed by laminating three canvas layers 1b; however, the number of laminated canvas layers lb is determined as appropriate. [0015] In the present invention, as illustrated in FIG. 3, the core body la of at 20 least one end 1A in the lengthwise direction of the belt main body 1 is formed ahead of time in a stepped shape (stepwise shape) by sequentially differentiating the lengths of the canvas layers lb laminated vertically adjacent to each other. It is preferable that a length L of the core body la formed ahead of time in a stepped shape be set to from 0.5 to 2.0 m. The reason is to 25 ensure the adhesion of an endless join based on the designated belt types defined for conveyer belts of textile construction in JIS K 6322-2011. The length of each step (the length by which each of the canvas layers lb protrudes in the lengthwise direction from a canvas layer lb laminated vertically adjacent) is, for example, approximately from 150 to 500 mm. 30 [0016] Next, the top of the core body la formed in this stepped shape is covered by a peeling member 3, and a cover rubber 4, which is an unvulcanized rubber, is laminated on the peeling member 3. The belt main body 1 in this state is vulcanized and molded ahead of time by a vulcanization apparatus or the like. 35 [0017] As the peeling member 3, one selected from members in the form of a heat resistant sheet, tape, or film is used. The members do not adhere to members constituting the belt main body 1 and do not fusion-bond thereto 6 during vulcanization. Specifically, as the peeling member 3, a vulcanized or unvulcanized rubber sheet, a release sheet formed from fluorine resin or the like, a polyethylene sheet, or the like is used. [0018] 5 Then, as illustrated in FIG. 4, in the usage site of the conveyor belt, the belt main body 1 is set by being pulled into the belt conveyor apparatus. Next, the peeling member 3 embedded in the belt main body 1 is peeled off from the belt main body 1. Accordingly, it is possible to easily eliminate the cover rubber 4 laminated on the peeling member 3. Along with this, the core body 10 la formed in a stepped shape which has been covered by the peeling member 3 is exposed. [0019] In this embodiment, an excess length portion IX of the belt main body 1 is left at a tip end side in the lengthwise direction of the belt main body 1 15 beyond the portion where the core body la is formed ahead of time in a stepped shape. Therefore, when joining the end 1A in the lengthwise direction of the belt main body 1, the belt main body 1 is pulled into the belt conveyor apparatus by grasping the excess length portion IX. Whether or not the excess length portion IX is provided is optional; however, the pulling work is 20 facilitated by providing the excess length portion IX. The excess length portion IX is cut away after the pulling of the belt main body 1. [0020] Next, as illustrated in FIG. 5, the other core body la formed in a stepped shape to be joined is placed to face the exposed core body la. The facing core 25 bodies la are laminated after adhesive Q or the like is applied onto at least one of the surfaces of the core bodies la. The laminated portion is inserted into a mold for vulcanization; then, the laminated portion is vulcanized and bonded by applying heat and pressure thereto at a fixed temperature for a fixed length of time so as to be joined. 30 [0021] According to the present invention as described above, since the core body la of the end in the lengthwise direction of the belt main body 1 is formed ahead of time in a stepped shape, the top of the core body la formed in this stepped shape is covered by the peeling member 3, and the belt main body 1 is 35 vulcanized and molded with the cover rubber 4 laminated on the peeling member 3, it is possible to prepare ahead of time the conveyor belt (the belt main body 1) in a belt manufacturing factory or the like. Then, when joining the end 1A in the lengthwise direction of the belt main body 1, it is possible to 7 eliminate the cover rubber 4 laminated on the peeling member 3 by peeling off the peeling member 3. Accordingly, it is possible to expose the core body la formed in a stepped shape which has been covered by the peeling member 3. [0022] 5 Therefore, the other core body la formed in a stepped shape to be joined is laminated on the exposed core body la so as to face the exposed core body la. Then, the portion where the core bodies la have been laminated is vulcanized and joined. Therefore, it is not necessary to perform complicated joining work at the usage site of the conveyor belt where there are constraints 10 on space or processing facilities as in the conventional art. That is, at the joining work site, since it is possible to simplify the cutting work, buffing work, or the like for the end 1A in the lengthwise direction of the belt main body 1, it is possible to significantly reduce the joining work time at the end 1A in the lengthwise direction of the conveyor belt compared to the conventional method. 15 [0023] In addition, since it is possible to prevent unnecessary scratching of the core body la by a cutting tool, there is an advantage in reducing variations in the quality of joins, generated depending on skills of workers and in improving the quality of the joins. 20 [0024] In a case where the length of the belt conveyor apparatus is short and the total length of the conveyor belt (the belt main body 1) is short, it is possible to accurately grasp ahead of time the circumferential length of the belt main body 1 with an endless form. In addition, there is a take-up mechanism which 25 adjusts the length by moving the driving roller 2A or the driven roller 2B in the longitudinal direction. [0025] Therefore, in such a case, the core bodies la of both ends 1A in the lengthwise direction of the belt main body 1 are formed ahead of time in a 30 stepped shape as in the present embodiment, the tops of the core bodies la formed in this stepped shape are covered by the peeling members 3, and the belt main body 1 can be vulcanized and molded with the cover rubbers 4 laminated on the peeling members 3. [0026] 35 On the other hand, in a case where the length of the belt conveyor apparatus is long and the total length of the conveyor belt (the belt main body 1) is long, it is difficult to accurately grasp ahead of time the circumferential length of the belt main body 1 with an endless form. In addition, there is no 8 take-up mechanism which is sufficient for adjusting the length by moving the driving roller 2A or the driven roller 2B in the longitudinal direction. [0027] Therefore, as illustrated in FIG. 6, the core body la of only one end in 5 the lengthwise direction of the belt main body 1 is formed ahead of time in a stepped shape. Then, the top of the core body la formed in this stepped shape is covered by the peeling member 3, and the belt main body 1 is vulcanized and molded with the cover rubber 4 laminated on the peeling member 3. The other core body la to be joined is formed in a stepped shape at the usage site of 10 the conveyor belt as in the conventional art. Then, it is also possible to laminate the core bodies la so that the core bodies la face each other and to vulcanize and join the laminated portion. [0028] For example, in joining work at four positions in a belt main body which 15 has a designated belt type of 1250 which is defined for conveyer belts in JIS K 6322-2011 and has a width of 1500 mm where four layers of polyester canvas were set as the core body, the conventional method required six workers, two days for the preparation, and three days for the work. On the other hand, it was possible to reduce the work time to approximately two-thirds including the 20 preparation time by applying the present invention illustrated in FIG. 5. Therefore, it was found that it is possible to reduce the number of workers to two. REFERENCE NUMBER 25 [0029] 1 Belt main body la Core body lb Canvas layer 1A End in lengthwise direction of belt main body 30 IX Excess length portion 2A Driving roller 2B Driven roller 2C Guide roller 3 Peeling member 35 4 Cover rubber Q Adhesive