Conveyor belt joining structure and conveyor belt

Abstract

To provide a joining structure for a conveyor belt that has excellent tensile strength.SOLUTION: A joining structure according to the present invention is an overlap structure, and comprises a core layer including canvas constituted of: warp threads extending in a belt length direction; and weft threads extending in a belt width direction. In a cross section of the canvas parallel to the belt length direction and perpendicular to the belt width direction, a region is defined by two straight lines that pass through centers of adjacent weft threads and extend in a thickness direction of the canvas, and when D is a length of a line segment connecting an innermost point in a thickness direction of a first curved portion of the warp thread formed bent with one weft thread and an outermost point in a thickness direction of a second curved portion of the warp thread formed bent with the other weft thread, and P is a pitch of the weft thread, an elongation rate of the warp thread calculated by D / P×100 is 2.20% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a joint structure for a conveyor belt and a conveyor belt including the joint structure. [Background technology]

[0002] Generally, a conveyor belt incorporated in a conveying device is an endless belt made up of one or more strip-shaped members whose ends are joined together. Known joining structures for conveyor belts include a butt (step) structure, an overlap structure, and a finger structure (Patent Document 1).

[0003] A conveyor belt that runs around a drive pulley and a driven pulley in a conveying device is always subjected to tension in the longitudinal direction, so the tensile strength in the longitudinal direction is taken into consideration when designing the joint structure of the conveyor belt.

[0004] For example, a butt structure is a structure in which the ends of the canvas provided in each belt-shaped member are joined together while facing each other. The number of layers of canvas in the butt structure is the same as the number of layers of canvas in the belt-shaped member before joining. Although this butt structure has low tensile strength, it has excellent flexibility in pulleys and is therefore suitable for applications with low loads and high safety factors. It has been known that the ratio of the tensile strength of the joined region of a butt structure in a conveyor belt to the non-joined region other than the joined region is approximately N / (N+1)%, where N is the number of layers of canvas. When the number of layers is 2, the ratio of the tensile strength of the joined region to the non-joined region is approximately 50%.

[0005] On the other hand, an overlap structure is a structure in which the canvas of each belt-shaped member is overlapped and joined in the belt thickness direction. The number of layers of canvas in the overlap structure is greater than the number of layers of canvas in the belt-shaped member before joining. Although this overlap structure has poor flexibility in pulleys, it has high tensile strength and is therefore considered suitable for applications with high loads and low safety factors. Conventionally, the joined region of an overlap structure in a conveyor belt has been recognized as having a tensile strength that is approximately 100%, regardless of the number of layers of canvas, similar to the non-joined region other than the joined region. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-232843 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the inventors have found that even in a bonded region formed with an overlapping structure, the tensile strength of the bonded region may be significantly lower than that of a non-bonded region. For example, the tensile strength of the bonded region may be insufficient depending on the specifications of the conveyor belt. Furthermore, the tensile strength of the bonded region may be insufficient depending on the bonding conditions.

[0008] In view of the above circumstances, an object of the present invention is to provide a joint structure for a conveyor belt having excellent tensile strength, and a conveyor belt having excellent tensile strength in the joint region. [Means for solving the problem]

[0009] The joining structure of the conveyor belt according to the present invention is an overlap structure in which a joining region in which end regions of a belt-shaped member including canvas are joined together is formed in the conveyor belt, and the canvas of the belt-shaped member is joined in a state where it is overlapped in the belt thickness direction so that the number of layers of the canvas in the joining region is greater than the number of layers of the canvas in a non-joined region other than the joining region of the conveyor belt, The canvas is a woven fabric made up of warp yarns extending in the belt length direction and weft yarns extending in the belt width direction, In a cross section of the canvas parallel to the belt length direction and perpendicular to the belt width direction, an area is divided by two straight lines that pass through the centers of adjacent wefts and extend in the thickness direction of the canvas, and when the length of the line segment connecting the innermost point in the thickness direction of the first curved portion of the warp formed by bending with one weft is D and the outermost point in the thickness direction of the second curved portion of the warp formed by bending with the other weft is P, the elongation rate of the warp calculated by D / P x 100 is 2.20% or more.

[0010] Such a joining structure has excellent tensile strength because the warp yarns can stretch in the length direction by an elongation rate of 2.20% or more and absorb tension.

[0011] Furthermore, a joining structure of a conveyor belt according to one aspect of the present invention includes: The warp threads are made of polyester fibers.

[0012] In this joint structure, the warp yarns are made of polyester fibers with relatively low elasticity, so the conveyor belt is less likely to stretch in the longitudinal direction and to become slack. The larger the slack that occurs in the conveyor belt, the more likely it is that the belt will need to be shortened (shortened in length) or a large-scale take-up device will be required to eliminate the slack. Therefore, the joint structure of the above aspect is advantageous in constructing a conveying device.

[0013] Furthermore, a joining structure of a conveyor belt according to one aspect of the present invention includes: The warp yarn has a fineness of 2,000 dtex or more and 5,000 dtex or less, The fineness of the weft yarn is 1,500 dtex or more and 3,000 dtex or less.

[0014] Such a joining structure has superior tensile strength when the warp and weft finenesses are within the above ranges.

[0015] Furthermore, a joining structure of a conveyor belt according to one aspect of the present invention includes: The density of the weft yarns is 15 or more and 30 or less per 5 cm.

[0016] Such a joining structure has even greater tensile strength when the weft density is within the above range.

[0017] The conveyor belt of the present invention includes any one of the above-described joint structures.

[0018] Such a conveyor belt has excellent tensile strength in the bonded region. [Effects of the Invention]

[0019] As described above, according to the present invention, it is possible to provide a joint structure for a conveyor belt having excellent tensile strength, and a conveyor belt having excellent tensile strength in the joint region. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 2 is a cross-sectional view of the joining structure of the embodiment. [Figure 2] 2A to 2C are diagrams illustrating a process for forming the junction structure of FIG. 1. [Figure 3] 1 shows a cross section of a canvas provided with a joining structure of an embodiment, the cross section being parallel to the length direction and perpendicular to the width direction. [Figure 4] FIG. [Figure 5] 5A to 5C are diagrams illustrating a process for forming the joint structure of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] A joint structure of a conveyor belt according to an embodiment of the present invention will be described below with reference to the drawings. Hereinafter, the directions of the conveyor belt may be referred to as a length direction D1 as a first direction, a width direction D2 as a second direction, and a thickness direction D3 as a third direction perpendicular to both the length direction D1 and the width direction D2. Furthermore, with regard to the surfaces of each member, the surface on the conveying side of the conveyor belt will be referred to as the front surface, and the surface on the back side of the conveyor belt that comes into contact with the pulley will be referred to as the back surface.

[0022] 1 and 2, the joint structure 1 of this embodiment is formed by joining end regions of a plurality of strip-shaped members, including a first strip-shaped member 1a and a second strip-shaped member 1b, in a longitudinal direction D1. In the joint structure 1, the second strip-shaped member 1b is joined from the front surface side of the first strip-shaped member 1a.

[0023] Each of the first belt-shaped member 1a and the second belt-shaped member 1b includes a core layer 10 including canvas, and a cover rubber 20 that covers the core layer 10. In this embodiment, the core layer 10 is disposed closer to the back surface of the joined structure 1 than the center of the thickness direction D3 of the joined structure 1. That is, the upper cover rubber 21, which is the cover rubber 20 on the front surface side via the core layer 10, is formed to be thicker than the lower cover rubber 22, which is the cover rubber 20 on the back surface side. Because the upper cover rubber 21 on the conveying surface side is thicker, durability (wear resistance) against conveyed objects can be made relatively high.

[0024] In the cross section of Figure 3, i.e., the cross section of the canvas parallel to the length direction D1 and perpendicular to the width direction D2, the canvas of the core layer 10 is a woven fabric composed of multiple warp threads 101 extending in the length direction D1 and weft threads 102 extending in the width direction D2. In each canvas, the weft threads 102 intersect with the warp threads 101 at a predetermined pitch P. The canvas of this embodiment has warp threads 101 formed from polyester-based fibers and weft threads 102 formed from polyamide-based fibers or polyester-based fibers. Canvas having warp threads 101 formed from polyester-based fibers has relatively little stretch in the length direction D1, and is therefore excellent at suppressing slack in the conveyor belt in the length direction D1.

[0025] The core layer 10 of this embodiment includes a first canvas 10a and a second canvas 10b laminated on the first canvas 10a. The core layer 10 may include one or more canvases.

[0026] In the end region of the first belt-shaped member 1a, the first canvas 10a extends further toward one side in the longitudinal direction D1 (the right side in FIG. 2) than the second canvas 10b, and the surface of the extending portion forms a first bonding surface 111 with the second belt-shaped member 1b. In addition, in the end region of the first belt-shaped member 1a, the surface of the second canvas 10b forms a second bonding surface 112 with the second belt-shaped member 1b. In other words, the end region of the first belt-shaped member 1a has a stepped bonding portion including the first bonding surface 111 of the first canvas 10a and the second bonding surface 112 of the second canvas 10b. In addition, in the end region of the first belt-shaped member 1a, the first canvas 10a extends further toward the one side in the longitudinal direction D1 (the right side in FIG. 2) than the lower cover rubber 22. Furthermore, in the end region of the first belt-shaped member 1a, the second canvas 10b extends further toward the one side (the right side in FIG. 2) in the length direction D1 than the upper cover rubber 21.

[0027] In the end region of the second belt-shaped member 1b, the back surface of the first canvas 10a forms a third bonding surface 113 with the first belt-shaped member 1a. In addition, in the end region of the second belt-shaped member 1b, the second canvas 10b extends further toward the other side in the longitudinal direction D1 (the left side in FIG. 2) than the first canvas 10a, and the back surface of the extended portion forms a fourth bonding surface 114 with the first belt-shaped member 1a. In other words, the end region of the second belt-shaped member 1b has a stepped bonding portion including the third bonding surface 113 of the first canvas 10a and the fourth bonding surface 114 of the second canvas 10b. In addition, in the end region of the second belt-shaped member 1b, the first canvas 10a extends further toward the other side in the longitudinal direction D1 (the left side in FIG. 2) than the lower cover rubber 22. Furthermore, in the end region of the second belt-shaped member 1b, the second canvas 10b extends further toward the other side (left side in FIG. 2) in the length direction D1 than the upper cover rubber 21.

[0028] In the joining structure 1, the first joining surface 111 of the first belt-shaped member 1a and the third joining surface 113 of the second belt-shaped member 1b are arranged opposite each other in the thickness direction D3 via an unvulcanized rubber sheet 31 (which becomes adhesive rubber after vulcanization), the second joining surface 112 of the first belt-shaped member 1a and the fourth joining surface 114 of the second belt-shaped member 1b are arranged opposite each other in the thickness direction D3 via the unvulcanized rubber sheet 31, and the end faces of the second canvas 10b of the first belt-shaped member 1a and the end faces of the first canvas 10a of the second belt-shaped member 1b are arranged opposite each other in the length direction D1 via the unvulcanized rubber sheet 31 and are vulcanized and integrated together. In addition, in the joining structure 1, the end 13a of the first canvas 10a of the second belt-shaped member 1b is covered and vulcanized with a rubber sheet 40 extending in the width direction D2, which is arranged between the end faces of the upper cover rubber 21 of each of the first belt-shaped member 1a and the second belt-shaped member 1b and the upper cover rubber 21 via an unvulcanized rubber sheet 32. Furthermore, in the joining structure 1, the end 13c of the first canvas 10a of the first belt-shaped member 1a is covered and vulcanized with a rubber sheet 50 extending in the width direction D2, which is arranged between the end faces of the lower cover rubber 22 of each of the first belt-shaped member 1a and the second belt-shaped member 1b and the lower cover rubber 22 via an unvulcanized rubber sheet 33.

[0029] In a conveyor belt equipped with such a joint structure 1, the number of layers of canvas (3) in the joint area including the joint structure 1 is greater than the number of layers of canvas (2) in the non-joined area other than the joint area. In other words, the joint structure 1 of this embodiment is an overlap structure in which the number of layers of canvas increases before and after joining.

[0030] A tension acts on the joining structure 1 in the conveying device in the length direction D1. Furthermore, the joining structure 1 in the conveying device has a boundary line (pitch line) between a region that is compressed (compressed region) and a region that is pulled (tensioned region) in the thickness direction D3 when bent by a pulley. At least one canvas in the joining structure 1 is arranged in the compression region, and all of the canvas may be arranged in the compression region. Since a compression force acts on the warp threads 101 of the canvas arranged in the compression region in the length direction D1 by the pulley, the smaller the degree of curvature in the thickness direction D3 (the closer it becomes to a straight line parallel to the length direction D1), the easier it is to bend, but repeated bending by a pulley with a small diameter makes the warp threads 101 more likely to buckle. Furthermore, at least one canvas in the joining structure 1 may be arranged in the tensioned region. The warp threads 101 of the canvas arranged in the tension area are subjected to tension in the longitudinal direction D1 by the pulley, so the smaller the degree of curvature in the thickness direction D3 (the closer it is to a straight line parallel to the longitudinal direction D1), the more difficult it is to absorb tension.

[0031] 3, the warp threads 101 of the canvas of this embodiment are curved in the thickness direction D3 at an angle to a straight line parallel to the length direction D1. That is, each warp thread 101 has multiple curved portions due to bending by each weft thread 102. Specifically, adjacent weft threads 102 are designated as the first weft thread 102a and the second weft thread 102b, and a first straight line L1 is drawn that passes through the center of the first weft thread 102a and extends in the thickness direction D3, and a second straight line L2 is drawn that passes through the center of the second weft thread 102b and extends in the thickness direction D3. In the region in the length direction D1 defined by the first straight line L1 and the second straight line L2, a line segment L is drawn connecting the innermost point x in the thickness direction D3 of the first curved portion of the warp thread 101 formed by bending it with the first weft thread 102a to the outermost point y in the thickness direction D3 of the second curved portion of the warp thread 101 formed by bending it with the second weft thread 102b, and the length of the line segment L is defined as D. The elongation of the warp thread 101 calculated by D / P×100 is 2.20% or more. The elongation is preferably 5% or less.

[0032] Furthermore, the angle that the line segment L makes with respect to a line parallel to the length direction D1 is preferably 12° or more and 18° or less.

[0033] The elongation rate and the angle can be obtained by taking out the canvas from the joint structure 1 and calculating the average values ​​of six arbitrarily selected points.

[0034] In order to achieve the above-mentioned elongation rate and impart the desired tensile strength to the joining structure 1, it is preferable that the fineness of the weft yarn 102 is 1,500 dtex or more and 3,000 dtex or less, preferably 2,000 dtex or more and 3,000 dtex or less, the density (number of threads per 5 cm) of the weft yarn 102 is 15 to 30 threads per 5 cm, and the fineness of the warp yarn 101 is 1,500 dtex or more.

[0035] Furthermore, in order to impart bending resistance in the length direction D1 to the joint structure 1, the density (number of threads) of the warp threads 101 is preferably 50 or more per 5 cm. Furthermore, the fineness of the warp threads 101 is more preferably 5,000 dtex or less. In detail, as shown in FIG. 1, on the back surface of the first canvas 10a in the second belt-shaped member 1b pressed by the end 13a of the first canvas 10a in the first belt-shaped member 1a, on the front surface of the second canvas 10b in the first belt-shaped member 1a pressed by the end 13b of the second canvas 10b in the second belt-shaped member 1b, on the back surface of the second canvas 10b in the second belt-shaped member 1b pressed by the end 13c of the second canvas 10b in the first belt-shaped member 1a, and on the front surface of the first canvas 10a in the first belt-shaped member 1a pressed by the end 13d of the first canvas 10a in the second belt-shaped member 1b, warp threads 101 with a large fineness that lack flexibility are likely to break. Therefore, the fineness of the warp threads 101 is preferably a thickness that reduces stress, i.e., 5,000 dtex or less.

[0036] The fineness of the warp yarns 101 may be smaller than, the same as, or larger than the fineness of the weft yarns 102. The density of the warp yarns 101 is usually larger than the density of the weft yarns 102. The total fineness of the warp yarns 101 is usually larger than the total fineness of the weft yarns 102. In this specification, the total fineness of the warp yarns 101 means the fineness per mm in the width direction D2, and the total fineness of the weft yarns 102 means the fineness per mm in the length direction D1.

[0037] Each of the warp yarns 101 and weft yarns 102 may be monofilament or multifilament. The warp yarns 101 are preferably multifilament. This makes the conveyor belt more easily bent around pulleys with small diameters. In the case of multifilament, the number of filaments is usually 2 to 4. The canvas of this embodiment can improve the bending resistance of the conveyor belt in the longitudinal direction D1 by having the elongation percentage of the warp yarns 101 be 2.20% or more. In other words, canvas containing monofilament warp yarns 101 can improve the bending resistance of the conveyor belt in the longitudinal direction D1 while suppressing the occurrence of slack in the conveyor belt.

[0038] The thickness of the joint structure 1 is, for example, 5 to 30 mm. The width of the joint structure 1 is, for example, 500 to 2800 mm. The thickness of the core layer 10 is, for example, 10 to 80% of the thickness of the joint structure 1.

[0039] The cover rubber 20 of this embodiment includes a layered upper cover rubber 21 that covers the core layer 10 from the front side, a layered lower cover rubber 22 that covers the core layer 10 from the back side, and a pair of ear rubbers (not shown) that cover the core layer 10 from both sides in the width direction D2.

[0040] The cover rubber 20 is formed from a rubber composition. The rubber composition contains rubber as a main component. The rubber composition may contain additives. Examples of the rubber include natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), isobutylene-isoprene rubber (IIR), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), chlorinated butyl rubber (CIIR), brominated butyl rubber (BIIR), silicone rubber (SR), urethane rubber (UR), acrylic rubber (ACR), and fluororubber (FR). The rubber composition may contain only one type of rubber or multiple types of rubber. Examples of the additives include fillers such as carbon black, silica, and calcium carbonate; flame retardants such as chlorinated paraffin, antimony trioxide, and ethylenebistetrabromophthalimide; crosslinking agents such as sulfur and organic peroxides; vulcanization accelerators such as zinc oxide; plasticizers such as paraffin oil and dioctyl adipate; antioxidants such as amine compounds and benzimidazole compounds; and lubricants such as stearic acid.

[0041] Although the embodiments have been described above as examples, the conveyor belt joining structure and conveyor belt according to the present invention are not limited to the configurations of the above-described embodiments. Furthermore, the conveyor belt joining structure and conveyor belt according to the present invention are not limited by the above-described effects. The conveyor belt joining structure and conveyor belt according to the present invention can be modified in various ways without departing from the spirit and scope of the present invention.

[0042] For example, in the above embodiment, a joint structure made up of a plurality of strip-shaped members is exemplified, but the joint structure according to the present invention may be one in which end regions of a single strip-shaped member are joined together.

[0043] This specification includes the following disclosure: (1) A joining structure of a conveyor belt, The joining structure is an overlap structure in which a joining region in which end regions of a belt-shaped member including canvas are joined together is formed in the conveyor belt, and the canvases of the belt-shaped member are joined in a state where they are overlapped in the belt thickness direction so that the number of layers of the canvas in the joining region is greater than the number of layers of the canvas in non-joined regions other than the joining region in the conveyor belt, The canvas is a woven fabric made up of warp yarns extending in the belt length direction and weft yarns extending in the belt width direction, A conveyor belt joining structure in which, in a cross section of the canvas parallel to the belt length direction and perpendicular to the belt width direction, an area is divided by two straight lines that pass through the centers of adjacent wefts and extend in the thickness direction of the canvas, and the length of the line connecting the innermost point in the thickness direction of a first curved portion of the warp formed by bending with one weft is D, and the outermost point in the thickness direction of a second curved portion of the warp formed by bending with the other weft is P, and the elongation rate of the warp calculated by D / P x 100 is 2.20% or more. (2) The joining structure of a conveyor belt according to (1), wherein the warp yarns are formed of polyester-based fibers. (3) The warp yarn has a fineness of 2,000 dtex or more and 5,000 dtex or less, The joining structure of a conveyor belt according to (1) or (2), wherein the weft yarn has a fineness of 1,500 dtex or more and 3,000 dtex or less. (4) The joining structure of a conveyor belt according to any one of (1) to (3), wherein the density of the weft yarns is 15 or more and 30 or less per 5 cm. (5) A conveyor belt comprising the joint structure according to any one of (1) to (4). [Example]

[0044] Next, the present invention will be explained in more detail by showing examples, but the present invention is not limited to these examples.

[0045] [Example 1] Two belt-shaped members were fabricated using the canvases listed in Table 1, each comprising a core layer made of a first canvas and a second canvas, and a cover rubber covering the core layer. The upper cover rubber of the first belt-shaped member was peeled off to form an end region with a stepped joint as shown in Figure 2. The lower cover rubber of the other belt-shaped member, the second belt-shaped member, was peeled off to form an end region with a stepped joint as shown in Figure 2. Unvulcanized rubber sheets (thickness: 0.4 to 1.0 mm) were attached to the joint surfaces of each of the canvases, and unvulcanized rubber sheets were filled between the butted ends of the lower cover rubber of the first belt-shaped member and the upper cover rubber of the second belt-shaped member, as well as between the butted ends of the upper cover rubber of the first belt-shaped member and the lower cover rubber of the second belt-shaped member. Test samples were fabricated by vulcanization for 25 minutes using a belt vulcanizer at a temperature of 140°C and a pressure of 0.6 to 1.0 MPa. The dimensions of the obtained test sample were 1200 mm in length, 300 mm in width, and 10 to 12 mm in thickness.

[0046] [Examples 2 to 5, Comparative Examples 1 and 2] Test samples were prepared in the same manner as in Example 1, except that the canvas shown in Table 1 was used.

[0047] [Evaluation of tensile strength] 50 mm wide test pieces were cut from each of the bonded and non-bonded regions of the test sample, and the test pieces were pulled at a speed of 100 m / min using a Shimadzu precision universal testing machine (Autograph, AG-250kNX) until they broke, and the tensile strength per unit width (N / mm) was determined. The strength ratio of the tensile strength of the bonded region to the non-bonded region was calculated by (tensile strength of the bonded region) / (tensile strength of the non-bonded region) × 100 and evaluated according to the following criteria. The results are shown in Table 1. (Evaluation criteria) ○: Intensity ratio is 80% or more ×: Intensity ratio is less than 80%

[0048] [Table 1]

[0049] [Comparative Examples 3 to 5] Using the canvases shown in Table 2, test samples with the butt-joint structure shown in Figure 4 were produced. Specifically, two strip-shaped members were produced, each having a core layer made of a first canvas and a second canvas, and a cover rubber covering the core layer. Next, the upper cover rubber of the first strip-shaped member was peeled off, forming an end region with a stepped joint as shown in Figure 5. Furthermore, the lower cover rubber of the second strip-shaped member was peeled off, forming an end region with a stepped joint as shown in Figure 5. An unvulcanized rubber sheet (0.4 to 1.0 mm thick) was attached to the joining surface of each canvas, and the end of the first canvas of the first belt-shaped member was butted against the end of the second canvas of the second belt-shaped member, and the end of the second canvas of the first belt-shaped member was butted against the end of the first canvas of the second belt-shaped member. Unvulcanized rubber sheets were filled between the butted ends of the lower cover rubber of the first belt-shaped member and the upper cover rubber of the second belt-shaped member, and between the butted ends of the upper cover rubber of the first belt-shaped member and the lower cover rubber of the second belt-shaped member. Vulcanization was carried out in the same manner as in Example 1 to obtain test samples. The test samples were evaluated using the evaluation methods described above. The results are shown in Table 2.

[0050] [Table 2] [Explanation of symbols]

[0051] 1: joint structure, 1a: first belt-shaped member, 1b: second belt-shaped member, 10: core layer, 10a: first canvas, 10b: second canvas, 101: warp, 102: weft, 102a: first weft, 102b: second weft, L1: first straight line, L2: second straight line, L: line segment, 111: first joint surface, 112: second joint surface, 113: third joint surface, 114: fourth joint surface, 13a, 13b, 13c, 13d: end, 20: cover rubber, 21: upper cover rubber, 22: lower cover rubber, 31, 32, 33: unvulcanized rubber sheet, 40: rubber sheet, 50: rubber sheet, D1: length direction, D3: thickness direction

Claims

1. A joining structure of a conveyor belt, The joining structure is an overlap structure in which a joining region in which end regions of a belt-shaped member including canvas are joined together is formed in the conveyor belt, and the canvases of the belt-shaped member are joined in a state where they are overlapped in the belt thickness direction so that the number of layers of the canvas in the joining region is greater than the number of layers of the canvas in non-joined regions other than the joining region in the conveyor belt, The canvas is a woven fabric made up of warp yarns extending in the belt length direction and weft yarns extending in the belt width direction, In a cross section of the canvas parallel to the belt length direction and perpendicular to the belt width direction, an area is divided by two straight lines that pass through the centers of adjacent wefts and extend in the thickness direction of the canvas, and when the length of the line connecting the innermost point in the thickness direction of a first curved portion of the warp formed by bending with one weft is D and the outermost point in the thickness direction of a second curved portion of the warp formed by bending with the other weft is P, the elongation rate of the warp calculated by D / P x 100 is 2.20% or more.

2. 2. The joining structure of a conveyor belt according to claim 1, wherein the warp yarns are made of polyester fibers.

3. The warp yarn has a fineness of 2,000 dtex or more and 5,000 dtex or less, 3. The joining structure of a conveyor belt according to claim 1, wherein the weft yarn has a fineness of 1,500 dtex or more and 3,000 dtex or less.

4. 3. The joining structure of a conveyor belt according to claim 1, wherein the density of the weft yarns is 15 or more and 30 or less per 5 cm.

5. A conveyor belt comprising the joint structure according to claim 1 or 2.

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