Pipe conveyor belt

Abstract

To provide a pipe conveyor belt that can maintain an appropriate cylindrical shape over a long period of time despite being easily deformed into a cylindrical shape, and that has excellent resistance to bending in the longitudinal direction.SOLUTION: A pipe conveyor belt according to the present invention 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 that is 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 4

Description

[Technical Field]

[0001] The present invention relates to a pipe conveyor belt. [Background technology]

[0002] Conventionally, conveying devices equipped with pipe conveyor belts have been used to prevent loads from spilling during transportation. The pipe conveyor belt is designed to run while alternately switching between a flat state where the transported objects are fed and a cylindrical state where the transported objects are covered.

[0003] Since pipe conveyor belts are repeatedly deformed as described above, their bending resistance in the width direction becomes an issue. Specifically, if a pipe conveyor belt has insufficient bending resistance in the width direction, when the belt is formed into a cylindrical shape, the ends in the width direction will sag, reducing the volume of the internal space and possibly degrading conveying performance. To address this issue, Patent Document 1 proposes using canvas containing highly elastic nylon weft yarns, and reducing bending fatigue by stretching the canvas in the width direction, thereby imparting bending resistance.

[0004] Furthermore, not only pipe conveyor belts but also conveyor belts in general are repeatedly bent by the pulleys of the conveying device, which poses a problem of bending resistance in the longitudinal direction. Patent Document 2 addresses this problem by noting that compressive stress is generated in the warp threads of canvas fabric bent by the pulleys, which can cause a phenomenon called buckling in the warp threads and lead to breakage. Patent Document 2 proposes suppressing warp buckling by increasing the degree of curvature of the warp threads in the longitudinal direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-97469 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-215017 Summary of the Invention [Problem to be solved by the invention]

[0006] In addition to the above performance, a pipe conveyor belt is required to be easily deformed from a flat shape that spreads in the width direction into a cylindrical shape. This performance is particularly important for pipe conveyor belts that are small in width (length in the width direction). In order to impart this performance, it is considered effective to reduce the fineness and density of the weft yarn in the canvas.

[0007] However, such weft yarns may reduce the bending resistance in the width direction, which may make it difficult to form a proper cylindrical shape over a long period of time. Furthermore, reducing the fineness and density of the weft yarns may lead to a decrease in the degree of curvature of the warp yarns, which may reduce the bending resistance in the length direction.

[0008] In view of the above circumstances, an object of the present invention is to provide a pipe conveyor belt that can maintain an appropriate cylindrical shape for a long period of time despite being easily deformed into a cylindrical shape, and that has excellent bending resistance in the longitudinal direction. [Means for solving the problem]

[0009] The pipe conveyor belt according to the present invention is a pipe conveyor belt used to convey an object while repeatedly deforming between a cylindrical closed state extending in the length direction and an open state widened in the width direction, A core layer including canvas and a cover rubber covering the core layer, The canvas is a woven fabric composed of warp yarns extending in the length direction and weft yarns extending in the width direction, The weft yarn has a fineness of 1,500 dtex or more and 3,000 dtex or less, The density of the weft yarn is 15 or more and 30 or less per 5 cm, The warp yarn has a fineness of 1,500 dtex or more, In a cross section of the canvas parallel to the length direction and perpendicular to the width direction, an area is divided by two straight lines that pass through the centers of adjacent weft threads 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 thread formed by bending it with one of the weft threads and the outermost point in the thickness direction of the second curved portion of the warp thread formed by bending it with the other weft thread is D and the pitch of the weft thread is P, the elongation rate of the warp thread calculated by D / P x 100 is 2.20% or more.

[0010] Such a pipe conveyor belt is easily deformed into a cylindrical shape by having a weft fineness of 3,000 dtex or less and a weft density of 30 threads per 5 cm or less. Furthermore, by having a weft fineness of 1,500 dtex or more and a weft density of 15 threads per 5 cm or more, the appropriate cylindrical shape can be maintained for a long period of time. Furthermore, by having a warp fineness of 1,500 dtex or more and a warp elongation rate of 2.20% or more, the belt has excellent bending resistance in the longitudinal direction. In addition, a warp elongation rate of 2.20% or more is also important for maintaining the appropriate cylindrical shape for a long period of time.

[0011] Furthermore, a pipe conveyor belt according to one aspect of the present invention comprises: The warp yarn has a fineness of 5,000 dtex or less, The density of the warp threads is 50 or more and 90 or less per 5 cm.

[0012] The pipe conveyor belt has excellent bending resistance in the longitudinal direction because the warp density is 50 or more per 5 cm. In addition, the warp fineness is 5,000 dtex or less and the warp density is 90 or less per 5 cm, which suppresses sagging of the ends in the width direction when formed into a cylindrical shape due to the weight of the canvas, and therefore allows for the formation of an appropriate cylindrical shape.

[0013] In a pipe conveyor belt according to one aspect of the present invention, the warp threads are formed of polyester fibers.

[0014] In such a pipe conveyor belt, the warp yarns are formed of polyester-based fibers with relatively low elasticity, so that the belt is less likely to stretch in the longitudinal direction and to become slack. The larger the slack that occurs in the pipe conveyor belt, the more it becomes necessary to shorten the belt (shorten the belt length) or to install a large-scale take-up device to eliminate the slack. Therefore, the pipe conveyor belt of the above embodiment is advantageous in constructing a conveying device.

[0015] Furthermore, the pipe conveyor belt according to one aspect of the present invention has a belt width of 1,100 mm or less.

[0016] A pipe conveyor belt with a belt width of 1,100 mm is usually assembled into a conveying device so that the inner diameter of the cylindrical belt is 300 mm. That is, a pipe conveyor belt with a belt width of 1,100 mm or less is assembled into a conveying device so that the inner diameter of the cylindrical belt is 300 mm or less. The pipe conveyor belt of the above-mentioned embodiment is easily deformed despite its relatively small inner diameter when it is cylindrical.

[0017] Furthermore, a pipe conveyor belt according to one aspect of the present invention comprises: The elongation of the warp yarns is 4.04% or less.

[0018] Such a pipe conveyor belt has better ability to maintain a proper cylindrical shape for a long period of time.

[0019] Furthermore, a pipe conveyor belt according to one aspect of the present invention comprises: The weft yarn has a fineness of 2,200 dtex.

[0020] Such a pipe conveyor belt has an even better ability to maintain a proper cylindrical shape for a long period of time. [Effects of the Invention]

[0021] As described above, according to the present invention, it is possible to provide a pipe conveyor belt that can maintain an appropriate cylindrical shape for a long period of time despite being easily deformed into a cylindrical shape, and that has excellent bending resistance in the longitudinal direction. [Brief explanation of the drawings]

[0022] [Figure 1] 10A and 10B are diagrams illustrating a state in which the pipe conveyor belt of the embodiment is deformed from an open state to a closed state. [Figure 2] 1A and 1B are diagrams showing a cross section of a pipe conveyor belt on a carrier side and a cross section of a return side of the pipe conveyor belt according to an embodiment. [Figure 3] FIG. 2 is a diagram showing a cross section parallel to the width direction of the pipe conveyor belt of the embodiment. [Figure 4] 1 shows a cross section of a canvas provided in a pipe conveyor belt of an embodiment, the cross section being parallel to the length direction and perpendicular to the width direction. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, a pipe conveyor belt according to an embodiment of the present invention will be described with reference to the drawings.

[0024] First, a conveying device equipped with the pipe conveyor belt of this embodiment will be described. Hereinafter, the directions of the pipe 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.

[0025] As shown in FIGS. 1 and 2, a conveying device A according to this embodiment includes an endless pipe conveyor belt 1, a drive pulley and a driven pulley (not shown) around which the pipe conveyor belt 1 is wound, and a plurality of support rollers a1 that support the pipe conveyor belt 1 so that it is cylindrical. As shown in FIG. 1, the conveying device A includes an open section s1 in which the pipe conveyor belt 1 is made flat to supply objects C toward the conveying surface of the pipe conveyor belt 1, and a closed section s2 in which the pipe conveyor belt 1 is made cylindrical by the plurality of support rollers a1 to prevent the objects C from falling. In the closed section s2, the pipe conveyor belt 1 is supported by the plurality of support rollers a1 so that both side ends in the width direction D2 overlap. The pipe conveyor belt 1 has a front surface that serves as a conveying surface on which the objects C are placed and a back surface opposite the conveying surface that is in contact with each pulley.

[0026] The conveying device A is advantageous for conveying an object C containing a powder or granular material that is prone to scattering. Examples of such an object C include coal, iron ore, wood chips, and pellets that are raw materials for various products.

[0027] As shown in Figs. 1 and 2, the plurality of support rollers a1 are arranged in a plurality of sets at predetermined intervals in the length direction D1. Each set includes at least a lower support roller a11 that supports the pipe conveyor belt 1 from below and an upper support roller a12 that supports the pipe conveyor belt 1 from above. Each set also includes a plurality of side support rollers a13 that support the pipe conveyor belt 1 from the width direction D2 between the lower support roller a11 and the upper support roller a12. Each support roller a1 is arranged so that its outer circumferential surface contacts the back surface of the pipe conveyor belt 1 and rotates along the conveying direction.

[0028] As shown in Fig. 2, the conveying device A is configured so that the pipe conveyor belt 1 is cylindrical not only on the carrier side (outbound side) CS where the pipe conveyor belt 1 runs toward the destination, but also on the return side (return side) RS where the pipe conveyor belt 1 runs from the destination toward the supply point of the conveyed object C. The conveying device A has a closed section s2 also on the return side RS, which can prevent some of the conveyed object C adhering to the conveying surface of the pipe conveyor belt 1 from falling.

[0029] The length of the closed section s2, including only the carrier side CS, is typically 100 m or more, and may be 500 m or more, or even 1 km or more. The conveying direction of the conveying device A may be horizontal or may be inclined upward or downward relative to the horizontal. Furthermore, the conveying direction of the conveying device A may be partially curved left or right.

[0030] The plurality of support rollers a1 are arranged in a plurality of sets at predetermined intervals in the belt length direction D1 on both the carrier side CS and the return side RS. As shown in FIG. 2, the lower support roller a11 in each set on the carrier side CS is arranged to support the widthwise center of the pipe conveyor belt 1. The upper support roller a12 in each set on the carrier side CS is arranged to support the overlapped both side edges of the pipe conveyor belt 1. On the other hand, the lower support roller a11 in each set on the return side RS is arranged to support the overlapped both side edges of the pipe conveyor belt 1. The upper support roller a12 in each set on the return side RS is arranged to support the widthwise center of the pipe conveyor belt 1. In addition to these, each set on the carrier side CS and the return side RS has a pair of side support rollers a13 that support the pipe conveyor belt 1 from the upper left and upper right, and a pair of side support rollers a13 that support the pipe conveyor belt 1 from the lower left and lower right.

[0031] The pipe conveyor belt 1 in the conveying device A repeatedly changes shape between a flat open state widened in the width direction D2 in the open section s1 and a cylindrical closed state extending in the conveying direction in the closed section s2.

[0032] As shown in Fig. 3, the pipe conveyor belt 1 of this embodiment includes a core layer 10 including canvas, and a cover rubber 20 covering the core layer 10. The core layer 10 of this embodiment is disposed closer to the back surface of the pipe conveyor belt 1 with respect to the center in the thickness direction D3 of the pipe conveyor belt 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 relatively high.

[0033] The pipe conveyor belt 1 is an endless belt in which the ends of one or more belt-shaped members are joined together to form a single continuous belt. That is, the pipe conveyor belt 1 has one or more joint regions formed by joining the ends of the belt-shaped members together.

[0034] The number of layers (plies) of canvas in the core layer 10 is preferably 2 or more and 3 or less, more preferably 2. This allows the pipe conveyor belt 1 to have the bonded region with sufficient strength while being easily deformed into a cylindrical shape.

[0035] In the cross section of Figure 4, i.e., the cross section of the canvas parallel to the length direction D1 and perpendicular to the width direction D2, each canvas 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 of polyester-based fibers and weft threads 102 formed of polyamide-based fibers or polyester-based fibers. Canvas having warp threads 101 formed of polyester-based fibers has relatively little stretchability in the length direction D1, and is therefore excellent at suppressing slack in the pipe conveyor belt 1 in the length direction D1.

[0036] As shown in FIG. 3, the core layer 10 of this embodiment includes a first canvas 10a and a second canvas 10b laminated on the first canvas 10a. The second canvas 10b is formed to be shorter in length in the width direction D2 than the first canvas 10a and is arranged so as not to overlap both side edges of the first canvas 10a. A third canvas 10c is laminated to form a pair on both side edges of the first canvas 10a. Furthermore, an intermediate rubber layer 11 is interposed between the first canvas 10a and the second canvas 10b. The second canvas 10b is arranged closer to the surface of the pipe conveyor belt 1 than the third canvas 10c by at least the thickness of the intermediate rubber layer 11. In this case, the number of canvas layers is two.

[0037] In the pipe conveyor belt 1 of this embodiment, the rigidity of the central region CA in the width direction D2, where the intermediate rubber layer 11 is arranged, is higher than that of the side regions SA, where the intermediate rubber layer 11 is not arranged, so that the pipe conveyor belt 1 can maintain an appropriate cylindrical shape even when an article C is placed thereon. From this perspective, the central region CA preferably has a width at least half the width of the pipe conveyor belt 1 so as to form a bottom large enough to receive the article C in the closed state. On the other hand, the side regions SA, where the load due to the article C is relatively small, have lower rigidity than the central region CA because the intermediate rubber layer 11 is not arranged, so that the side regions SA are more likely to bend by the support rollers a1. In addition, by reducing the rigidity of the side regions SA, the contact pressure at the overlapping portions of both side ends in the belt width direction when the pipe conveyor belt 1 deforms into a cylindrical shape can be reduced, and wear of the surfaces of the side regions SA due to sliding can be suppressed.

[0038] The thickness of the intermediate rubber layer 11 is preferably 0.4 to 2.0 mm, which makes it possible to increase the rigidity in the central region CA while maintaining flexibility in the longitudinal direction D1.

[0039] The intermediate rubber layer 11 may be formed of the same rubber composition as the cover rubber 20, or may be formed of a rubber composition that can impart a higher elastic modulus (hardness) than the cover rubber 20, in order to further increase the rigidity of the central region CA in the width direction D2 where the intermediate rubber layer 11 is disposed. Alternatively, in order to reduce costs, the intermediate rubber layer 11 may be formed of an inexpensive rubber composition that contains recycled rubber.

[0040] The pipe conveyor belt 1 in the conveying device A has a boundary line (pitch line) between a region that is compressed (compressed region) and a region that is tensioned (tensioned region) in the thickness direction D3 when bent by each pulley. At least one canvas in the core layer 10 is arranged in the compressed region, and all canvas may be arranged in the compressed region. Since a compressive force acts on the warp threads 101 of the canvas arranged in the compressed 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 more likely it is that the warp threads 101 of the canvas will buckle when repeatedly bent by the pulley.

[0041] Therefore, in the cross section of Figure 4, the warp threads 101 of the canvas of this embodiment are curved in the thickness direction D3 so as to form an angle with respect to a straight line parallel to the length direction D1. That is, each warp thread 101 has multiple curved portions due to being bent by the weft threads 102. Specifically, in the cross section of Figure 4, adjacent weft threads 102 are 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 the first weft thread 102a with the outermost point y in the thickness direction D3 of the second curved portion of the warp thread 101 formed by bending the second weft thread 102b. When the length of the line segment L is 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, more preferably 4.04% or less, and even more preferably 4.00% or less. This allows the appropriate cylindrical shape to be maintained for a long period of time. Another advantage is that the thickness of the canvas can be reduced. This advantage is particularly advantageous when the number of layers of canvas is two or more.

[0042] The angle that the line segment L makes with respect to a straight line parallel to the length direction D1 is preferably 12° or more and 18° or less, and more preferably 12° or more and 16° or less.

[0043] The elongation rate and the angle can be obtained by taking out the canvas from the pipe conveyor belt 1 and calculating the average values ​​at six arbitrarily selected points.

[0044] To easily deform the pipe conveyor belt 1 into a cylindrical shape and achieve the above-mentioned elongation rate of the warp yarns 101, the fineness of the weft yarns 102 is 1,500 dtex to 3,000 dtex, preferably 2,000 dtex to 3,000 dtex, and more preferably 2,200 dtex. It is important that the density (number of threads per 5 cm) of the weft yarns 102 is 15 to 30 threads per 5 cm, and that the fineness of the warp yarns 101 is 1,500 dtex or more.

[0045] In order to impart bending resistance to the pipe conveyor belt 1 in the length direction D1, the density (number of threads) of the warp threads 101 is preferably 50 or more per 5 cm.

[0046] Furthermore, to prevent sagging of the side region SA (at the carrier side CS) over a long period of time when the pipe conveyor belt 1 is cylindrical, the density of the warp yarns 101 is preferably 90 threads per 5 cm or less, and the fineness of the warp yarns 101 is more preferably 5,000 dtex or less. Also, from the viewpoint of preventing sagging of the side region SA, the fineness of the weft yarns 102 is preferably 3,000 dtex or less. The reason for this is that if the weft yarns 102 are too thick, they lack flexibility, making the canvas prone to bending and breaking. This is thought to be particularly noticeable in the portions of the first canvas 10a that are pressed by the end of the intermediate rubber layer 11 in the width direction D2 and the end of the third canvas 10c in the width direction D2 that faces the end of the intermediate rubber layer 11. On the other hand, if the fineness of the weft yarns 102 is appropriately thin, stress can be reduced due to flexibility. Furthermore, when the weft threads 102 of the canvas become thinner, the degree of curvature of the warp threads 101 in the thickness direction D3 becomes relatively smaller, and the elongation rate of the warp threads 101 tends to become smaller. Therefore, from the viewpoint of ensuring an elongation rate of the warp threads 101 of 2.20% or more, the fineness of the weft threads 102 is preferably 1500 dtex or more, and more preferably 2000 dtex or more.

[0047] 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.

[0048] Each of the warp yarns 101 and the weft yarns 102 may be monofilament or multifilament. The warp yarns 101 are preferably multifilament. This makes the pipe conveyor belt 1 more easily bendable around pulleys with small diameters. In the case of multifilament, the number of filaments is usually 2 to 4. In the canvas of this embodiment, the elongation percentage of the warp yarns 101 is 2.20%, which can improve the bending resistance of the pipe conveyor belt 1 in the longitudinal direction D1.

[0049] The thickness of the pipe conveyor belt 1 is, for example, 5 to 30 mm. The width of the pipe conveyor belt 1 is, for example, 600 to 2800 mm. The width of the pipe conveyor belt 1 may be 600 mm or more and 1100 mm or less. In this case, the inner diameter of the pipe conveyor belt 1 when formed into a cylindrical shape is 150 mm or more and 300 mm or less. The thickness of the core layer 10 is, for example, 10 to 80% of the thickness of the pipe conveyor belt 1.

[0050] The cover rubber 20 of this embodiment includes a layered upper cover rubber 21 that covers the core layer 10 from the surface side, a layered lower cover rubber 22 that covers the core layer 10 from the back side, and a pair of ear rubbers 23 that cover the core layer 10 from both sides in the width direction D2.

[0051] 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.

[0052] Although the embodiments have been shown as examples, the pipe conveyor belt according to the present invention is not limited to the configurations of the above-mentioned embodiments. Furthermore, the pipe conveyor belt according to the present invention is not limited by the above-mentioned effects. The pipe conveyor belt according to the present invention can be modified in various ways without departing from the gist of the present invention.

[0053] This specification includes the following disclosures. (1) A pipe conveyor belt used to transport objects while repeatedly changing between a cylindrical closed state extending in the length direction and an open state widened in the width direction, A core layer including canvas and a cover rubber covering the core layer, The canvas is a woven fabric composed of warp yarns extending in the length direction and weft yarns extending in the width direction, The weft yarn has a fineness of 1,500 dtex or more and 3,000 dtex or less, The density of the weft yarn is 15 or more and 30 or less per 5 cm, The warp yarn has a fineness of 1,500 dtex or more, In a cross section of the canvas parallel to the length direction and perpendicular to the 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 one of the wefts and the outermost point in the thickness direction of a second curved portion of the warp formed by bending the other weft is D, and the pitch of the weft is P. This is a pipe conveyor belt in which the elongation rate of the warp calculated by D / P x 100 is 2.20% or more. (2) The warp yarn has a fineness of 5,000 dtex or less, The pipe conveyor belt according to (1), wherein the density of the warp yarns is 50 or more and 90 or less per 5 cm. (3) The pipe conveyor belt according to (1) or (2), wherein the warp yarns are formed of polyester fibers. (4) The pipe conveyor belt according to any one of (1) to (3), wherein the belt width is 1,100 mm or less. (5) The pipe conveyor belt according to any one of (1) to (4), wherein the elongation of the warp yarns is 4.04% or less. (6) The pipe conveyor belt according to any one of (1) to (5), wherein the weft has a fineness of 2,200 dtex. [Example]

[0054] Next, the present invention will be explained in more detail by showing examples, but the present invention is not limited to these examples.

[0055] [Example 1] Using the canvas shown in Table 1, a first canvas with adhesive rubber on its surface was laminated onto an unvulcanized sheet for the lower cover rubber. An unvulcanized sheet for the intermediate rubber layer was laminated to the center region of the first canvas, excluding both side edges. A second canvas with adhesive rubber on its surface was then laminated onto this unvulcanized sheet. A third canvas with adhesive rubber on its surface was then laminated to both side edges of the first canvas, and an unvulcanized sheet for the upper cover rubber was then laminated to produce a pre-vulcanized laminate. Next, the laminate was vulcanized and integrated under specified pressure and temperature conditions using a belt vulcanizer to obtain a test sample. The dimensions of the resulting test sample were 75 mm long, 1000 mm wide, approximately 10 mm thick, and the intermediate rubber layer was approximately 2 mm thick.

[0056] [Examples 2 to 9, Comparative Examples 1 to 3] Test samples were prepared in the same manner as in Example 1, except that the canvas shown in Table 1 was used.

[0057] [Cylindrical deformation performance] Using the six support rollers shown in Figure 2, it was observed whether the test sample was supported in a cylindrical shape with an inner diameter of 250 mm, and the results were evaluated according to the following evaluation criteria. The results are shown in Table 1. (Evaluation criteria) ○: Can be supported cylindrically ×: Cannot support cylindrically

[0058] [Long-term cylindrical maintenance performance] The test sample was bent 300,000 times, repeatedly changing between a flat and cylindrical shape. The total reaction force generated on each support roller was measured before and after the test. The rigidity retention rate (%) of the test sample was calculated by dividing the total reaction force after bending by the total reaction force before bending × 100, and evaluated according to the following criteria. The results are shown in Table 1. (Evaluation criteria) ○: Retention rate is 70% or more ×: Retention rate is less than 70%

[0059] [Flexibility in the longitudinal direction] Using the canvas shown in Table 1, test samples measuring 25 mm wide and 500 mm long were prepared. Using a Scott-type bending tester, the samples were wrapped around a 100 mm diameter pulley and subjected to 300,000 reciprocating motions. Then, using a tensile tester (Shimadzu Autograph), the tensile strength (N / mm) in the longitudinal direction was measured before and after bending. The breaking strength retention rate (%) was calculated by dividing the breaking strength of the test sample after bending by the breaking strength of the test sample before bending, and evaluated according to the following criteria. The results are shown in Table 1. (Evaluation criteria) ○: Retention rate is 90% or more △: Retention rate is between 85% and 90% ×: Retention rate is less than 85%

[0060] [Table 1] [Explanation of symbols]

[0061] A: conveying device, 1: pipe conveyor belt, 10: core layer, 10a: first canvas, 10b: second canvas, 10c: third canvas, 11: middle rubber layer, 101: warp, 102: weft, 102a: first weft, 102b: second weft, L1: first straight line, L2: second straight line, L: line segment, 20: cover rubber, a1: support roller, a11: lower support roller, a12: upper support roller, a13: side support roller, C: conveyed object, s1: open section, s2: closed section, CS: carrier side, RS: return side, D1: length direction, D2: width direction, D3: thickness direction

Claims

1. A pipe conveyor belt used to transport objects while repeatedly changing between a cylindrical closed state extending in the length direction and an open state widened in the width direction, A core layer including canvas and a cover rubber covering the core layer, The canvas is a woven fabric composed of warp yarns extending in the length direction and weft yarns extending in the width direction, The weft yarn has a fineness of 1,500 dtex or more and 3,000 dtex or less, The density of the weft yarn is 15 or more and 30 or less per 5 cm, The warp yarn has a fineness of 1,500 dtex or more, In a cross section of the canvas parallel to the length direction and perpendicular to the 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. 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 the other weft is D, and the pitch of the weft is P, the elongation rate of the warp calculated by D / P x 100 is 2.20% or more.

2. The warp yarn has a fineness of 5,000 dtex or less, 2. The pipe conveyor belt according to claim 1, wherein the density of the warp yarns is 50 to 90 per 5 cm.

3. 3. The pipe conveyor belt according to claim 1, wherein the warp yarns are made of polyester fibers.

4. 3. The pipe conveyor belt according to claim 1 or 2, wherein the belt width is 1,100 mm or less.

5. 2. The pipe conveyor belt according to claim 1, wherein the elongation of the warp yarns is 4.04% or less.

6. 6. The pipe conveyor belt according to claim 5, wherein the weft yarn has a fineness of 2,200 dtex.

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