Pipe conveyor belt

Abstract

To provide a pipe conveyor belt capable of suppressing damage caused by a reinforcing member and being used for a long time.SOLUTION: A pipe conveyor belt according to the present invention includes at least one fabric forming a core-body layer, a reinforcing member layered on the core-body layer, and a cover rubber covering the fabric and the reinforcing member, wherein a tensile strength of the reinforcing member in a width direction is greater than a tensile strength of the fabric in the width direction, and a ratio of the tensile strength of the reinforcing member in the width direction to the tensile strength of the fabric in the width direction is 2.0 or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a conveying device equipped with a pipe conveyor belt has been used to prevent spillage of cargo during conveyance. The pipe conveyor belt is in a flat state at the point where the transported goods are supplied or discharged, and in a cylindrical state that covers the transported goods in the transporting range, and is incorporated into the conveying device so as to travel while repeating such deformations.

[0003] A pipe conveyor belt usually comprises a canvas forming a core layer and a cover rubber covering the canvas. The pipe conveyor belt is required to have rigidity in the width direction because it is repeatedly deformed as described above. If the pipe conveyor belt has insufficient rigidity in the width direction, when it is made into a cylindrical shape, the ends in the width direction will sag, reducing the volume of the internal space, which may result in a deterioration in conveying performance.

[0004] Therefore, pipe conveyor belts equipped with reinforcing members to increase the rigidity of the belt are known. An advantage of a pipe conveyor belt equipped with a reinforcing member is that, for example, when the belt is used continuously for a long period of time, the frequency of replacement or repair can be reduced. For example, Patent Documents 1 and 2 propose that cords having a predetermined rigidity are arranged in the vicinity of the core layer so as to be parallel to the belt width direction, thereby maintaining a practical level of rigidity for a long period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-72220 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-1462 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors attempted to increase the rigidity of the reinforcing member to form a cylindrical shape that would be stable over a longer period of time, and discovered that a reinforcing member with excessive rigidity could cause damage such as cracks to form from within the cover rubber. They also discovered that if the rigidity of the reinforcing member is too high relative to the canvas that forms the core layer, damage from within the cover rubber becomes even more likely to occur.

[0007] In view of the above circumstances, an object of the present invention is to provide a pipe conveyor belt that can suppress damage caused by reinforcing members and can be used for a long period of time. [Means for solving the problem]

[0008] The pipe conveyor belt according to the present invention comprises: 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, The bag comprises one or more canvases forming a core layer, a reinforcing member laminated on the core layer, and a cover rubber covering the canvases and the reinforcing member, The tensile strength of the reinforcing member in the width direction is greater than the tensile strength of the canvas in the width direction, and the ratio of the tensile strength of the reinforcing member to the tensile strength of the canvas in the width direction is 2.0 or less.

[0009] In a pipe conveyor belt of this configuration, the ratio of the tensile strength in the width direction of the reinforcing member to the tensile strength in the width direction of the canvas of the core layer is 2.0 or less, which suppresses damage caused by the reinforcing member and enables it to be used for a long period of time.

[0010] Moreover, one aspect of the pipe conveyor belt of the present invention is The reinforcing member is arranged so that a center portion in a width direction thereof coincides with a center portion in a width direction of the pipe conveyor belt, The ratio of the width of the reinforcing member to the width of the pipe conveyor belt is 0.60 or more and 0.75 or less.

[0011] The pipe conveyor belt having such a configuration has relatively low rigidity at both ends in the width direction where no reinforcing members are arranged, and damage caused by contact between the ends when the belt is made into a cylindrical shape is suppressed, resulting in excellent maintenance performance against bending in the width direction.

[0012] Moreover, one aspect of the pipe conveyor belt of the present invention is the reinforcing member is a reinforcing fabric having weft yarns extending in the width direction, The weft yarn is made of polyester fiber.

[0013] The weft yarn made of polyester fiber has the advantage that it is less likely to stretch than other chemical fibers such as nylon fiber, and therefore it is easier to maintain a proper cylindrical shape.

[0014] In an embodiment in which the weft is made of polyester fiber, the fineness of the weft per mm in the length direction of the belt is preferably 1000 dtex or more and 3000 dtex or less.

[0015] The pipe conveyor belt having such a configuration, having a fineness of 1000 dtex or more and 3000 dtex or less, is easily deformed into a cylindrical shape from the beginning of use, has excellent performance in maintaining bending in the width direction for a relatively long period of time, and further suppresses damage caused by the reinforcing members. [Effects of the Invention]

[0016] As described above, according to the present invention, it is possible to provide a pipe conveyor belt that can suppress damage caused by reinforcing members and can be used for a long period of time. [Brief explanation of the drawings]

[0017] [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. 1 is a diagram schematically illustrating a cross section parallel to the width direction of a pipe conveyor belt having a reinforcing member on the conveying surface side of a core layer. [Figure 4] FIG. 1 is a diagram schematically illustrating a cross section parallel to the width direction of a pipe conveyor belt having a reinforcing member on the contact surface side with a pulley with respect to a core layer. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a pipe conveyor belt according to an embodiment of the present invention will be described with reference to the drawings.

[0019] First, a conveying device including a pipe conveyor belt according to the present embodiment will be described. Hereinafter, the various directions of the pipe conveyor belt may be referred to as the length direction, the width direction, and the direction perpendicular to both the length direction and the width direction as the thickness direction.

[0020] As shown in Figures 1 and 2, the conveying device A of 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.

[0021] The pipe conveyor belt may be endless, with longitudinal ends of one belt-shaped member joined together. The pipe conveyor belt may also be endless, with ends of multiple belt-shaped members joined together to form a single continuous belt. Due to this joining, the pipe conveyor belt has one or more joint regions formed by joining the ends of the belt-shaped members together.

[0022] As shown in Figure 1, the conveying device A has 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 a 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 to form a cylindrical shape with both ends in the width direction D2 overlapping. The pipe conveyor belt 1 has a front surface 101 as a conveying surface on which the objects C are placed, and a back surface 102 on the opposite side from the conveying surface that comes into contact with each pulley.

[0023] 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.

[0024] As shown in Fig. 1, the plurality of support rollers a1 are arranged in a plurality of sets at predetermined intervals in the length direction D1. As shown in Fig. 2, 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 102 of the pipe conveyor belt 1 and rotates along the conveying direction.

[0025] 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 of the conveyed object C, 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, thereby preventing some of the conveyed object C attached to the conveying surface of the pipe conveyor belt 1 from falling.

[0026] 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.

[0027] 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 center portion in the width direction of the pipe conveyor belt 1. Moreover, the upper support roller a12 in each set on the carrier side CS is arranged to support both overlapping ends of the pipe conveyor belt 1 in the width direction. On the other hand, the lower support roller a11 in each set on the return side RS is arranged to support both overlapping ends of the pipe conveyor belt 1 in the width direction. Moreover, the upper support roller a12 in each set on the return side RS is arranged to support the center portion in the width direction 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.

[0028] The pipe conveyor belt 1 in the conveying device A repeatedly changes shape between a flat open state in the open section s1 where it spreads in the width direction D2 and a cylindrical closed state in the closed section s2 where it extends in the conveying direction.

[0029] 3 and 4, the pipe conveyor belt 1 includes one or more canvases 10 forming a core layer, a reinforcing member 20 laminated on the core layer, and a cover rubber 30 covering the canvases 10 and the reinforcing member 20. The layer formed by the reinforcing member 20 is a reinforcing layer that reinforces the core layer and also reinforces the pipe conveyor belt 1 itself.

[0030] Each canvas is a woven fabric made up of multiple warp threads (hereinafter referred to as first warp threads) extending in the belt length direction and weft threads (hereinafter referred to as first weft threads) extending in the belt width direction. On the other hand, the reinforcing member of this embodiment is a woven fabric as a reinforcing cloth made up of multiple warp threads (hereinafter referred to as second warp threads) extending in the belt length direction and weft threads (hereinafter referred to as second weft threads) as wire rods extending in the belt width direction.

[0031] When the core layer is formed from two or more canvases, the canvases are bonded together with adhesive rubber, that is, in this case, two or more canvases are bonded together with adhesive rubber to form one laminate.

[0032] When the core layer is formed from only one canvas, the reinforcing fabric is adhered to one of the pair of surfaces of the canvas with adhesive rubber. When the core layer is formed from two or more canvases, the reinforcing fabric is adhered to one of the pair of surfaces of the laminate with adhesive rubber. Furthermore, to further increase the rigidity of the belt in the width direction, an intermediate rubber layer may be formed between the canvas and the reinforcing fabric. The thickness of the intermediate rubber layer is preferably 3.0 mm or less, more preferably 1.0 mm or less. This makes it possible to increase the rigidity of the belt in the width direction while suppressing an increase in the mass of the belt and the power required to run the belt.

[0033] Furthermore, when the canvas adjacent to the reinforcing fabric in the belt thickness direction among the one or more canvases is designated as a reinforced canvas, the ratio of the tensile strength of the reinforcing fabric in the belt width direction to the tensile strength of the reinforced canvas in the belt width direction is 2.0 or less. Having similar tensile strengths for the reinforced canvas and the reinforcing fabric prevents the reinforcing member from peeling off from the core layer, thereby reducing damage caused by the reinforcing member. Specifically, in a pipe conveyor belt that repeatedly deforms between a flat open state and a cylindrical closed state, a reinforcing member that peels off from the core layer may move inside the cover rubber and push up against the cover rubber from the inside, destroying it. Therefore, preventing the reinforcing member from peeling off from the core layer is important for long-term use. From this perspective, the ratio here is preferably 1.5 or less. Typically, the tensile strength of the reinforcing fabric in the belt width direction is greater than the tensile strength of the reinforced canvas in the belt width direction. Preferably, the ratio here is 1.2 or more.

[0034] When the core layer is formed of two or more canvases, the ratio of the tensile strength of the reinforcing fabric in the belt width direction to the tensile strength of the canvases other than the reinforced canvas in the belt width direction is preferably 2.0 or less, more preferably 1.5 or less, and more preferably 1.2 or more.

[0035] The tensile strength of the reinforced canvas in the belt width direction is preferably 40 N / mm or more and 120 N / mm or less, more preferably 40 N / mm or more and 100 N / mm or less, and even more preferably 40 N / mm or more and 80 N / mm or less. When the core layer is formed from two or more canvases, the ratio of the tensile strength of the canvases other than the reinforced canvas in the belt width direction to the tensile strength of the reinforced canvas in the belt width direction is preferably 0.9 or more and 1.1 or less, and more preferably 1.0.

[0036] The tensile strength of the reinforcing fabric in the belt width direction is preferably 150 N / mm or less, more preferably 100 N / mm or less, and even more preferably 80 N / mm or less. The tensile strength of the reinforcing fabric in the belt width direction is preferably 50 N / mm or more.

[0037] The tensile strength of the canvas in the belt length direction is, for example, 100 N / mm or more and 600 N / mm or less, and the tensile strength of the reinforcing fabric in the belt length direction is, for example, 50 N / mm or more and 100 N / mm or less.

[0038] The tensile strength of the canvas and the reinforcing fabric is measured in accordance with the measurement method described in JIS K6377-7 (Conveyor rubber belt - Determination of tensile properties). The test specimens are prepared by cutting out an A-type test specimen having the entire thickness (total thickness) of the pipe conveyor belt to measure the tensile strength in the belt width direction and belt length direction, and then dividing each layer of each test specimen (upper and lower cover rubber, canvas, reinforcing fabric) in the thickness direction. The tensile strength in the belt width direction and belt length direction is measured using each test specimen divided in the thickness direction. If it is difficult to separate and extract only the canvas (reinforced canvas) or the reinforcing fabric, the canvas (reinforcing fabric) may be divided in the thickness direction with a thin layer of rubber remaining on the surface, so long as it does not affect the tensile strength.

[0039] The first warp threads of the canvas are preferably made of polyester or nylon fibers. When the first warp threads of the canvas are made of polyester fibers, they have higher rigidity and are less likely to stretch than other chemical fibers such as nylon fibers, which can prevent slack in the belt length direction. On the other hand, when the first warp threads of the canvas are made of nylon fibers, they have lower rigidity and are more likely to stretch than polyester fibers, but they are easier to bend in the belt length direction, which has the advantage that they can be easily wound around pulleys with smaller diameters than canvas made of polyester fibers.

[0040] The first weft of the canvas is preferably formed from polyester fiber.

[0041] The second weft of the reinforcing fabric is preferably formed from polyester-based fibers. Such second wefts are more rigid and less likely to stretch than wires formed from other chemical fibers, such as nylon-based fibers, and therefore have the advantage of maintaining the proper cylindrical shape of the pipe conveyor belt for a long period of time. On the other hand, wires (second wefts) with the advantages of polyester-based fibers can be relatively small in their expansion and contraction, which is expected to prevent damage to the cover rubber from the inside. However, using wires with excessively high rigidity in a pipe conveyor belt may result in damage to the cover rubber from the inside. One reason for this is that even wires formed from polyester-based fibers may experience unexpected expansion and contraction during belt operation. Specifically, the greater the difference in rigidity between the first weft of the canvas forming the core layer and the second weft of the reinforcing fabric, the greater the difference in expansion and contraction between the adjacent layers of the cover rubber at positions corresponding to the core layer and the reinforcing layer in the belt thickness direction, which is thought to result in stress fracture of the cover rubber. Therefore, in order to take advantage of the above-mentioned advantages of polyester-based fibers while suppressing stress fracture in the cover rubber, it is particularly important to make the ratio of the tensile strength of the reinforcing fabric in the belt width direction to the tensile strength of the reinforced canvas in the belt width direction 2.0 or less.

[0042] The first warp yarn of the canvas is preferably a multifilament yarn, which makes it easier to wind the pipe conveyor belt around a pulley. The first weft yarn of the canvas is preferably a multifilament yarn, which makes it easier to bend the pipe conveyor belt into a trough shape (U-shape) or a cylindrical shape.

[0043] The fineness (single yarn fineness) of the first weft yarn of the canvas is preferably 1000 dtex or more and 2000 dtex or less. The fineness (single yarn fineness) of the first warp yarn of the canvas is, for example, 1000 dtex or more and 3000 dtex or less, and may be 1500 dtex or more and 2500 dtex or less.

[0044] The density (number of threads) of the first weft of the canvas is preferably 20 or more and 30 or less per 50 mm in the belt length direction.

[0045] The fineness of the first weft yarn of the canvas per 1 mm in the length direction of the belt is preferably 500 dtex or more and 1500 dtex or less, and more preferably 600 dtex or more and 1000 dtex or less. The fineness here can be calculated by (fineness of the first weft yarn of the canvas) x (density of the first weft yarn of the canvas) / 50 mm.

[0046] The second weft yarns of the reinforcing cloth are preferably monofilaments, which can increase the rigidity of the pipe conveyor belt in the width direction. On the other hand, the second warp yarns of the reinforcing cloth are preferably multifilaments, which can make it easier to wind the pipe conveyor belt around a pulley.

[0047] The fineness (single yarn fineness) of the second weft yarn of the reinforcing fabric is preferably 1000 dtex or more and 2000 dtex or less, and more preferably 1500 dtex or more and 2000 dtex or less. The difference between the fineness (single yarn fineness) of the second weft yarn of the reinforcing fabric and the fineness (single yarn fineness) of the first weft yarn of the canvas is preferably 500 dtex or less, more preferably 400 dtex or less, even more preferably 300 dtex or less, and even more preferably 200 dtex or less. The fineness of the second warp yarn of the reinforcing fabric may be, for example, 1000 dtex or more and 2000 dtex or less, or 1000 dtex or more and 1500 dtex or less.

[0048] The density (number of threads) of the second weft of the reinforcing fabric is preferably 40 to 50 per 50 mm in the belt length direction.

[0049] The fineness of the second weft yarn of the reinforcing fabric per 1 mm in the belt length direction is preferably 1,000 dtex or more and 3,000 dtex or less, and more preferably 1,400 dtex or more and 1,600 dtex or less. By setting an upper limit on the fineness of the second weft yarn, the pipe conveyor belt can be easily deformed into a cylindrical shape from the beginning of use. In addition, since the rigidity of the second weft yarn is reduced, damage to the cover rubber caused by the second weft yarn can be suppressed. On the other hand, by setting a lower limit on the fineness of the second weft yarn, the pipe conveyor belt can be endowed with the ability to maintain its resistance to bending in the width direction for a relatively long period of time. The fineness here can be calculated by (fineness of the second weft yarn of the reinforcing fabric) × (density of the second weft yarn of the reinforcing fabric) / 50 mm.

[0050] The density (number of threads) of the second warp yarns of the reinforcing fabric is preferably, for example, 30 to 40 threads per 50 mm in the belt width direction.

[0051] The fineness of the second warp threads of the reinforcing fabric per 1 mm in the belt width direction is, for example, 500 dtex to 1500 dtex. The fineness here can be calculated by (fineness of the second warp threads) × (density of the second warp threads of the reinforcing fabric) / 50 mm.

[0052] The number of layers (plies) of canvas in the core layer is preferably 2 or more and 4 or less, and more preferably 3.

[0053] The number of layers of the reinforcing fabric relative to the core layer is preferably 1. Furthermore, in a cross section parallel to the width direction D2 shown in FIGS. 3 and 4 , the reinforcing member 20 is arranged so that its widthwise center coincides with the widthwise center of the pipe conveyor belt 1. Here, when the width of the pipe conveyor belt is W and the circumferential length when the pipe conveyor belt is cylindrical is C, the ratio of the circumferential length C to the width W is usually set to about 80%. That is, the ratio of the width of the reinforcing member to the width of the pipe conveyor belt is usually set to about 0.8. Meanwhile, in this embodiment, the ratio of the width of the reinforcing member 20 to the width W of the pipe conveyor belt 1 is 0.60 or more and 0.75 or less. Furthermore, this ratio is more preferably 0.60 or more and 0.70 or less. This relatively reduces the rigidity of both end regions of the pipe conveyor belt 1, suppressing damage due to contact between the end regions when the pipe conveyor belt is cylindrical, resulting in excellent retention performance against bending in the width direction D2. In addition, the overall rigidity of the pipe conveyor belt 1 in the width direction is also reduced, making it easier to deform into a cylindrical shape, thereby reducing the power required to deform the pipe conveyor belt 1 from a flat shape to a cylindrical shape while it is running. In other words, although the pipe conveyor belt 1 is easily deformed into a cylindrical shape, it has excellent ability to maintain bending in the width direction D2.

[0054] Furthermore, the width of each canvas is preferably 80% or more of the width (total width) of the pipe conveyor belt. The pipe conveyor belt preferably does not include a member narrower than the width of the reinforcing fabric. For example, such a member may be a second reinforcing member arranged in the belt thickness direction so as to overlap both ends of the reinforcing fabric in the width direction in order to prevent the reinforcing fabric from peeling off from the core layer. A pipe conveyor belt that does not include such a narrow member has the advantage of being easy to manufacture. Specifically, a pipe conveyor belt is usually manufactured by advancing each belt-shaped member while aligning it in the length direction and arranging each member at a predetermined position in the width direction. In this case, narrow members are prone to deviation or meandering, making it difficult to accurately arrange them at a predetermined position in the width direction, so it is preferable not to include such a member.

[0055] A pipe conveyor belt that does not include such narrow members is preferable because the thickness can be reduced accordingly. The thickness of the pipe conveyor belt is, for example, 5 to 30 mm.

[0056] It is considered that the influence of the difference in expansion and contraction increases as the width of the pipe conveyor belt increases, so that the pipe conveyor belt preferably has a width of 1000 mm or more and 3000 mm or less.

[0057] As shown in Figures 3 and 4, the cover rubber 30 includes a first cover rubber layer 31 that covers one or more canvases 10 and reinforcing members 20 from the front surface 101 side, a second cover rubber layer 32 that covers one or more canvases 10 and reinforcing members 20 from the back surface 102 side, and a pair of ear rubbers 33 that cover one or more canvases 10 and reinforcing members 20 from both sides in the width direction D2.

[0058] The cover rubber 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.

[0059] The intermediate rubber layer may be formed of the same rubber composition as the cover rubber 30, or may be formed of a rubber composition that can impart a higher elastic modulus (hardness) than the cover rubber 30. Alternatively, for the purpose of reducing costs, the intermediate rubber layer may be formed of an inexpensive rubber composition that includes recycled rubber.

[0060] 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.

[0061] For example, the reinforcing layer may be formed of an assembly of a plurality of cords arranged to extend in the belt width direction. The tensile strength of such a reinforcing layer in the width direction can be measured in the same manner as for the reinforcing fabric described above.

[0062] 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, The bag comprises one or more canvases forming a core layer, a reinforcing member laminated on the core layer, and a cover rubber covering the canvases and the reinforcing member, A pipe conveyor belt, wherein the tensile strength of the reinforcing member in the width direction is greater than the tensile strength of the canvas in the width direction and the ratio of the tensile strength of the reinforcing member to the tensile strength of the canvas in the width direction is 2.0 or less. (2) The reinforcing member is arranged so that a center portion in a width direction thereof coincides with a center portion in a width direction of the pipe conveyor belt, The pipe conveyor belt according to (1) above, wherein a ratio of the width of the reinforcing member to the width of the pipe conveyor belt is 0.60 or more and 0.75 or less. (3) the reinforcing member is a reinforcing fabric having weft yarns extending in the width direction, The pipe conveyor belt according to (1) or (2) above, wherein the weft yarns are formed of polyester-based fibers. (4) The pipe conveyor belt according to any one of (1) to (3) above, wherein the fineness of the weft yarns per mm in the length direction of the belt is 1000 dtex or more and 3000 dtex or less. [Example]

[0063] Next, the present invention will be explained in more detail by showing examples, but the present invention is not limited to these examples.

[0064] Table 1 below shows the material and physical properties of one canvas for forming the core layer.

[0065] [Table 1]

[0066] [Example 1] Using the canvas shown in Table 1 and the reinforcing cloth shown in Table 2 below, three sheets of canvas with adhesive rubber on their surfaces were laminated onto an unvulcanized sheet for the second cover rubber layer. Another reinforcing cloth with adhesive rubber on its surface was laminated on the conveying surface of the canvas so that the width ratio of the reinforcing cloth to the belt width was 0.62. An unvulcanized sheet for the first cover rubber layer was then laminated on top of the reinforcing cloth to produce a pre-vulcanization laminate. Next, the laminate was vulcanized and integrated using a belt vulcanizer under specified pressure and temperature conditions to produce a pipe conveyor belt. The resulting pipe conveyor belt had a thickness of approximately 12 mm.

[0067] [Example 2] As shown in Table 2, a pipe conveyor belt was produced in the same manner as in Example 1, except that the width ratio of the reinforcing fabric to the belt width was changed to 0.70.

[0068] [Example 3] As shown in Table 2, a pipe conveyor belt was produced in the same manner as in Example 1, except that a reinforcing fabric was laminated on the surface of the canvas that would come into contact with the pulley.

[0069] [Example 4] As shown in Table 2, a pipe conveyor belt was produced in the same manner as in Example 2, except that a reinforcing fabric was laminated on the surface of the canvas that would come into contact with the pulley.

[0070] [Example 5] As shown in Table 2, a pipe conveyor belt was produced in the same manner as in Example 1, except that the width ratio of the reinforcing fabric to the belt width was changed to 0.78.

[0071] [Comparative Example 1] A pipe conveyor belt was produced in the same manner as in Example 1, except that no reinforcing fabric was laminated on the canvas (core layer).

[0072] Comparative Example 2 A pipe conveyor belt was produced in the same manner as in Example 2, except that the reinforcing fabrics shown in Table 2 were used.

[0073] Comparative Example 3 Pipe conveyor belts were produced in the same manner as in Example 5, except that the reinforcing fabrics shown in Table 2 were used.

[0074] [Damage prevention with reinforcing fabric] Test samples (25 mm long, 500 mm wide) were cut out from each pipe conveyor belt, wrapped around a 100 mm diameter pulley so that the test samples were bent in the width direction, and bent 1 million times to observe whether the reinforcing fabric peeled off from the canvas. The results are shown in Table 2.

[0075] [Cylindrical deformation performance] Test samples (75 mm long, 1000 mm wide) were cut out from each pipe conveyor belt, and supported in a cylindrical shape with an inner diameter of 250 mm using the six support rollers shown in Figure 2. The total repulsive force (N) exerted by the test samples on the support rollers was measured. Evaluation was performed according to the following evaluation criteria, with the repulsive force of Comparative Example 1 as the standard. The results are shown in Table 2. (Evaluation criteria) ○: Repulsion index less than 200 relative to the repulsion of 100 in Comparative Example 1 ×: Repulsion index of 200 or more relative to the repulsion of 100 in Comparative Example 1

[0076] [Maintenance performance against bending in the width direction] Test samples prepared to evaluate cylindrical deformation performance were bent 300,000 times in the width direction. The total repulsive force generated in each support roller after bending was measured and evaluated according to the following criteria, with the repulsive force of Comparative Example 1 (no bending) as the standard. The results are shown in Table 2. (Evaluation criteria) ○: Repulsion index of 100 or more relative to the repulsion of Comparative Example 1, which is 100 ×: Repulsion index less than 100 relative to the repulsion of Comparative Example 1, which is 100

[0077] [Table 2] [Explanation of symbols]

[0078] A: conveying device, 1: pipe conveyor belt, 101: surface, 102: back surface, 10: canvas, 20: reinforcing member, 30: cover rubber, 31: first cover rubber layer, 32: second cover rubber layer, 33: ear 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, The inflatable bag includes one or more canvases forming a core layer, a reinforcing member laminated on the core layer, and a cover rubber covering the canvases and the reinforcing member, A pipe conveyor belt, wherein the tensile strength of the reinforcing member in the width direction is greater than the tensile strength of the canvas in the width direction and the ratio of the tensile strength of the reinforcing member to the tensile strength of the canvas in the width direction is 2.0 or less.

2. The reinforcing member is arranged so that a center portion in a width direction thereof coincides with a center portion in a width direction of the pipe conveyor belt, 2. The pipe conveyor belt according to claim 1, wherein a ratio of a width of the reinforcing member to a width of the pipe conveyor belt is 0.60 or more and 0.75 or less.

3. the reinforcing member is a reinforcing fabric having weft yarns extending in the width direction, The pipe conveyor belt according to claim 1 or 2, wherein the weft yarns are made of polyester fibers.

4. 4. The pipe conveyor belt according to claim 3, wherein the fineness of the weft yarns per 1 mm in the length direction of the belt is 1,000 dtex or more and 3,000 dtex or less.

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