Conveyor belt

Abstract

The conveyor belt has a conveying surface, and a canvas exposed on the reverse side opposite the conveying surface is made of warp and weft yarns, and the value of a surface property parameter (Sk) using a load curve in a square judgment area set on the reverse side, each side of which is 10 mm or more, is 150 or less.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority based on Japanese Patent Application No. 2023-114609, the entire disclosure of which is incorporated herein by reference. [Technical field]

[0002] The present invention relates to a conveyor belt used in a belt conveyor. [Background technology]

[0003] A belt conveyor used to transport objects placed on it includes a number of pulleys and a transport belt that is wound around the pulleys and moves in a circular motion. The transport belt is made of a fabric such as canvas, whose longitudinal direction is long in accordance with the transport direction.

[0004] Here, the invention described in Patent Document 1 (Japanese Patent No. 6894906) aims to reduce noise during operation. Patent Document 1 describes that in a fabric constituting a belt for conveying, etc., warp threads and weft threads are crossed at an inclination angle other than a right angle, and the weft threads are formed in a wavy shape. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent No. 6894906 Summary of the Invention [Problem to be solved by the invention]

[0006] However, such a configuration in which the warp and weft threads are set in a special positional and shaped relationship is not preferable because it requires a special manufacturing device (such as a loom) to manufacture the belt. Among the noises mentioned above, there is one that is caused by the conveyor belt moving in the conveying direction hitting the table, pulleys, etc. that support the conveyor belt in the belt conveyor. More specifically, this noise is thought to be caused by the back surface of the conveyor belt moving relative to the table or pulley not smoothly transitioning to a contact state.

[0007] Therefore, the present invention provides: By smoothly transitioning the back surface of the conveyor belt moving in the conveying direction to a state of contact with the table, pulley, etc.,No special manufacturing equipment is required and transportation is possible. This occurs when the conveyor belt hits a table, pulley, etc. An object of the present invention is to provide a conveyor belt configured to reduce noise. [Means for solving the problem]

[0008] The present invention is a conveying belt having a conveying surface and capable of conveying an object to be conveyed that is brought into contact with the conveying surface by being moved in a longitudinal direction, the conveying belt having canvas exposed at least on its reverse side opposite the conveying surface, the canvas being composed of warp threads arranged along the longitudinal direction and weft threads arranged crossing the warp threads, and the conveying belt having a surface property parameter (Sk) value of 150 or less using a load curve in a square judgment area set on the reverse side, the square judgment area having one side of 10 mm or more.

[0009] Also, a multifilament may be used as the warp yarn, and a monofilament may be used as the weft yarn.

[0010] The warp threads and the weft threads may be made of polyester.

[0011] The canvas exposed on the back surface may be impregnated with an adhesive. [Brief description of the drawings]

[0012] [Figure 1] 2 is a schematic diagram showing a cross section of a back canvas in a conveyor belt according to one embodiment of the present invention, with the back side facing up. FIG. [Diagram 2] 2 is a schematic diagram showing a configuration of the entire conveyor belt in a vertical cross section; FIG. [Figure 3A] FIG. 1 is a schematic front view showing a method for measuring noise of a prototype belt. [Figure 3B] FIG. 1 is a schematic plan view showing a method for measuring noise of a prototype belt. [Figure 3C] FIG. 1 is a schematic left side view showing a method for measuring noise of a prototype belt. [Figure 4]1 is a graph for explaining a surface texture parameter (Sk) using a load curve. [Diagram 5] 4 is a table showing configurations of the transport belts of the examples and comparative examples, which are prototype belts, and noise measurement results. [Figure 6] 6 is a graph showing the relationship between the surface quality parameter (Sk) and the noise characteristic (AP250) using the load curve for the examples and comparative examples of the conveyor belt shown in FIG. 5. [Figure 7] 6 is a graph showing the relationship between the surface quality parameter (Sk) and the noise characteristic (AP200) using the load curve for the example and the comparative example of the conveyor belt shown in FIG. 5. [Figure 8] 6 is a graph showing the relationship between the surface quality parameter (Sk) and the noise characteristic (AP150) using the load curve for the examples and the comparative examples of the conveyor belt shown in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the surface (front side) that the object to be conveyed contacts during conveyance is referred to as the conveying surface, and the surface on the opposite side to the conveying surface (the surface that contacts the pulleys, rollers, and table of the belt conveyor) is referred to as the back side. In accordance with this, the terms "front side" and "back side" are used to express directions.

[0014] The conveyor belt 1 of the present embodiment is applied to, for example, a light conveyor belt used for conveying luggage at logistics sites, etc. The conveyor belt 1 is formed into an endless ring shape with one end and the other end connected, has a conveying surface, and is moved in the longitudinal direction by a circulating motion during operation, thereby being able to convey objects to be conveyed that are in contact with the conveying surface.

[0015] 2, the conveyor belt 1 has a two-ply structure in which two sheets of canvas (front canvas 11, back canvas 12) are bonded together and integrated via an intermediate resin layer 13 (made of thermoplastic polyurethane in this embodiment). The surface of the front canvas 11 is covered with a cover resin layer 14.

[0016] FIG. 1 shows a schematic cross section of the back canvas 12. The weave of the back canvas 12 shown in FIG. 1 is a 2 / 2 twill weave (FIG. 1 shows the weave along one warp thread 2). In FIG. 1, the surface located on the upper side (on which the front canvas 11 is laminated via an intermediate resin layer 13 as shown in FIG. 2) is shown facing downward when the back canvas 12 is attached to the belt conveyor. Each of the canvases 11, 12 is constructed by weaving a warp thread 2 and a weft thread 3 made of polyester. By weaving, a convex region 4 protruding to the back side and a concave region 5 concave to the front side are formed on the back side of the back canvas 12. The part of the convex region 4 facing the concave region 5 is a step 41. Multifilament is used for the warp thread 2, and monofilament is used for the weft thread 3. By using a relatively flexible multifilament for the warp thread 2, the conveyor belt 1 can be easily bent to fit along the pulley when attached to the belt conveyor. For this reason, it is less likely to shake during operation. On the other hand, by using a relatively stiff monofilament for the weft yarn 3, unnecessary deformation of the conveyor belt in the width direction can be suppressed, and the objects to be conveyed can be stably supported. In addition, excessive deformation caused by being pressed by components of the belt conveyor when the belt comes into contact with the components can also be prevented.

[0017] The warp threads 2 are arranged along the longitudinal direction of the conveyor belt 1, and the weft threads 3 are arranged to cross the warp threads 2 in a plan view of the conveyor belt 1. In this embodiment, the weft threads 3 are arranged perpendicular to the warp threads 2, but they may be configured to cross at an angle other than a right angle. As shown in FIG. 2, the canvas on the conveyor surface side is covered with a cover resin layer 14 (made of thermoplastic polyurethane in this embodiment), and this cover resin layer 14 abuts against the object to be conveyed. In addition, the canvas 12 exposed on the back surface is impregnated with an adhesive. As a result, the end of the width direction of the conveyor belt 1 is hardened by the adhesive, so that it is possible to suppress the occurrence of fuzzing at the end due to a part of the warp threads 2 (multifilament) coming off the canvas 12. In addition, when a guide member for preventing meandering is attached to the back surface of the conveyor belt 1 by welding, it can be installed without roughening. Incidentally, when the canvas is impregnated with an adhesive, it becomes hard and tends to make a louder sound when it comes into contact with a support such as a pulley or a table, which is disadvantageous from the viewpoint of noise reduction. However, in this embodiment, since noise can be reduced by setting the value of the surface quality parameter (Sk) using the load curve to 150 or less as described below, the canvas is impregnated with adhesive to prevent fuzzing and to facilitate the attachment of the guide members. With the above-mentioned configuration, at least the canvas (impregnated with adhesive in this embodiment) is exposed on the back surface located on the side opposite the conveying surface.

[0018] An example of a manufacturing method for the conveyor belt 1 is shown below. First, two pieces of prepared canvas 11, 12 are subjected to a primer treatment to impregnate them with a resin solution. In this embodiment, the canvas is impregnated with a urethane resin adhesive solution. Next, heated resin is poured between the two pieces of canvas 11, 12. In this embodiment, the resin is extruded from a T-die using an extrusion molding technique. This resin becomes the intermediate resin layer 13 in the conveyor belt 1. Next, the two pieces of canvas 11, 12 with the resin poured in are sandwiched between two laminating rolls and pressure-bonded to be integrated.

[0019] In the present embodiment, the conveyor belt 1 is exposed on the back surface of the canvas 12 on which the convex region 4 and the concave region 5 are formed. In the case where a square-shaped judgment region with a side of 10 mm or more is set, the value of the surface property parameter (Sk) using the load curve in the judgment region (inside the region) is set to 150 or less. In the present embodiment, the judgment region is a square with a side of 10 mm. It is preferable from the viewpoint of judgment accuracy to set the dimension of one side of the judgment region to be large, since it is possible to absorb the measurement variation. For this reason, the upper limit value of the dimension of one side of the judgment region is not particularly limited. In other words, the upper limit value is the width dimension of the conveyor belt 1.

[0020] The surface texture parameter (Sk) is defined in ISO25178 "Geometric Product Specifications (GPS)-Surface Texture" and is one of the various parameters for evaluating the surface roughness of three-dimensional surface textures. This Sk is a parameter indicating the level difference of the core portion (the level difference between the upper and lower limits of the height of the core portion) described later. Sk can be measured by a commercially available three-dimensional shape measuring instrument. Therefore, it is easy to use it as an evaluation standard for the unevenness of the back surface of the conveyor belt 1.

[0021] The surface texture parameter (Sk) will be briefly described. First, the area ratio of the part that is at or above a certain height in the judgment region, based on the height of a set plane (reference plane), is called the "area load ratio". As shown in FIG. 4, a curve (a curve that appears on a graph in which the area load ratio is shown on the horizontal axis and the height is shown on the vertical axis) that shows the height change between 0% and 100% of this area load ratio is called the "load curve". Then, a tangent (straight line) drawn to the load curve in a section in which the difference in the area load ratio (the difference in the horizontal axis of the graph) is 40%, where the slope of the load curve in the 40% section is the gentlest, is called an equivalent line. Then, the height range (range from minimum to maximum) when the equivalent line is extended over the section between the area load ratio of 0% and 100% is called a core part. The difference in level between the top and bottom of this core part is Sk. Incidentally, the portion higher than the upper end of the core portion is called a protruding peak portion, and the portion lower than the lower end of the core portion is called a protruding valley portion, but the height dimensions of these protruding peak portions and protruding valley portions are excluded from Sk.

[0022] There are various parameters for surface roughness. For example, along with the above-mentioned Sk (core roughness depth), there are Spd (peak density), Smr2 (area ratio separating the protruding valleys and the core), and Sxp (pole height), which are specified in ISO25178. The inventors of the present application have also investigated these and other parameters, but have decided to adopt the above-mentioned surface texture parameter (Sk) because it separates the surface textures of different weaves with the highest accuracy and has been found to have a correlation with noise characteristics.

[0023] Here, at least a part of the noise caused by the conveyor belt 1 is generated by the conveyor belt 1 hitting the table or pulley that supports the conveyor belt 1 in the belt conveyor. The cause of this noise is not directly related to the type of weave of the fabric that constitutes the canvas. The following are reasons why the parameter Sk contributes to the reduction of noise of the conveyor belt 1 in this embodiment. First, the part corresponding to the core part in the load curve of FIG. 4, which occupies the majority of the fabric that constitutes the conveyor belt 1, actually comes into contact with the table or pulley when it comes into contact with the table or pulley. The lower the value of Sk, the gentler the slope of the load curve at the core part, indicating that the height changes gradually. This means that the flatness of the back surface of the canvas 12 is high. Therefore, it is presumed that a lower value of Sk ensures the parallelism of the conveyor belt 1 when it comes into contact with the table or pulley (i.e., the back surface of the conveyor belt 1 that is moving relative to the table or pulley does not tilt or wobble excessively, and smoothly transitions to a contact state), resulting in lower noise. In this embodiment, the unevenness on the rear surface of the conveyor belt 1 can be made small corresponding to an Sk value of 150 or less, so that noise caused by the unevenness can be reduced.

[0024] In particular, the conveyor belt 1 for logistics applications is often operated at high speeds to increase the conveying speed, and there is a demand for reducing noise generated during high-speed operation in order to improve the environment at the installation site. The conveyor belt 1 of the present embodiment can fully meet this demand.

[0025] Among the multiple layers of canvas (two-ply in this embodiment), the weave of at least the canvas exposed on the back side (specifically, the back canvas 12) can be, for example, twill or satin. Note that these are representative examples and are not limited to these. In this embodiment, as long as the value of Sk is the same, the type of weave is not particularly important from the perspective of noise control. Twill and satin weaves are more expensive to manufacture than plain weaves, which have traditionally been common weaves for conveyor belts, but can be selected when noise control is important. Note that the weave of the back canvas 12 shown in Figure 1 is a 2 / 2 twill weave (Figure 1 is shown along one warp thread 2). EXAMPLES

[0026] Next, the inventor of the present application created a prototype belt 10 according to a plurality of different configurations (Examples) and Comparative Examples, and measured the noise, which will be described below. The prototype belt 10 to be measured used a polyester fabric woven in a plain weave with a warp density of 84 / 5cm and a weft density of 52 / 5cm as the front canvas 11 (see FIG. 2, the same as for the configuration of the prototype belt 10 below), and a canvas similar to the polyester fabric as the back canvas 12, but with a weave structure and weft count changed as shown in FIG. 5, was used in Examples 1 to 6 and Comparative Examples 1 to 6. The examples were twill weave, more specifically, Examples 1 to 3 were 2 / 2 twill weave, and Examples 4 to 6 were 3 / 1 twill weave. The weft density of the back canvas 12 was 60 to 85 / 5cm, more specifically, 63 to 83 / 5cm. The intermediate resin layer 13 used adipate ester thermoplastic polyurethane. The warp threads 2 constituting each of the canvases 11 and 12 are multifilaments (1100 dtex / 192 f) made of polyethylene terephthalate, and the weft threads 3 are monofilaments (1100 dtex) made of polyethylene terephthalate. The lamination of each of the canvases 11 and 12 was performed in the manner described above as an example of the manufacturing method. The back canvas 12 was previously impregnated with a urethane resin adhesive solution in the manner described above. Note that the cover resin layer 14 was not provided for the front canvas 11.

[0027] As shown in Fig. 3A to Fig. 3C, the prototype belt 10 (circumference 260 cm, width 10 cm, thickness 1.4 mm) formed in an endless loop was stretched between pulleys P, P of a two-shaft belt conveyor and supported by a table T made of stainless steel alloy. For safety reasons, the test belt conveyor was placed in a frame equipped with a wire mesh (the frame is not shown in Fig. 3A to Fig. 3C). A microphone M was installed facing the table, with the tip of the sound collecting part positioned at the same height as the table T (i.e., the upper belt passing position on the belt conveyor), in the center of the longitudinal direction of the table T, and 1 m away from the edge of the width direction of the prototype belt 10 in a direction perpendicular to the belt longitudinal direction. The sound level meter used was "NA-29E" manufactured by Rion Co., Ltd. The measurement was performed indoors. The indoor environment was such that the total noise (background noise) when the belt was stopped was 60 dB or less.

[0028] The noise value (total noise) when the belt area to be measured was located horizontally to the side of microphone M was adopted as the measured value. Among the noise measurement conditions, the frequency weighting characteristic was A-characteristic, and the time weighting characteristic was F (fast). The running speed of prototype belt 10 was 150 m / min. Although tests were also conducted at other speeds, the measurement performed at 150 m / min will be explained here as a representative example. The boundary for noise evaluation of the total noise at a running speed of 150 m / min was set to 74 dB. This value was set with the goal of reducing noise by approximately 10 dB from the noise level of approximately 85 dB for conveyor belts with a plain weave structure.

[0029] FIG. 5 shows the canvas configuration (weave diagram, weave structure, density of weft yarn 3 (number of weft yarns 3 per 5 cm in the longitudinal direction)), surface property parameter (Sk), and noise characteristics of the back canvas 12 of Examples 1 to 6, which are prototypes of the conveyor belt 1 according to the present invention among the prototype belts 10, and Comparative Examples 1 to 6. In the noise measurement results AP250, AP200, and AP150, the alphabetic letter "AP" represents the all-pass value, which is the sum of the noise levels of all frequencies (dB). The numbers "250", "200", and "150" represent the conveying speed (m / min) of the prototype belt. The surface property parameter (Sk) was obtained by performing measurements using a 3D shape measuring instrument VR-6000 manufactured by Keyence Corporation. The measurement conditions were 25x auto magnification, S filter (low pass filter) 8 mm, and L filter (high pass filter) 8 mm.

[0030] 6 to 8 show graphs in which the horizontal axis is the surface property parameter (Sk) and the vertical axis is the noise characteristic (dB) for AP250 (FIG. 6), AP200 (FIG. 7), and AP150 (FIG. 8) for the prototype belts of the examples and comparative examples, plotted based on the results shown in FIG. 5, with a thick vertical line indicating Sk of 150. As can be seen from each figure, the prototype belts of the examples, whose plotted points are Sk of 150 or less, have smaller noise characteristic values ​​than the prototype belts corresponding to the comparative examples. The Sk values ​​clearly supported by the examples are 145 or less, but since it can be said with common sense that the change in noise characteristic with respect to the change in Sk is not rapid, the first digit is rounded off to 150 or less as described above. In addition, from the experimental results, it can be said that the noise assessment boundary for total noise when the running speed is 150 m / min is 74 dB, while the noise assessment boundary for total noise when the running speed is 200 m / min is 76 dB, and the noise assessment boundary for total noise when the running speed is 250 m / min is 79 dB.

[0031] As described above, it has been clearly confirmed that the surface property parameter (Sk) affects the quietness of the conveyor belt 1. This is based on a new viewpoint that has not been seen before, and since it does not require the formation of a special weave structure as described in, for example, Patent Document 1 (Japanese Patent No. 6894906), it is possible to provide a low-noise conveyor belt 1 using a low-cost general manufacturing method. Therefore, according to the present invention, a significant noise reduction effect can be obtained at low cost.

[0032] The present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the gist of the present invention.

[0033] For example, the number of plies of the canvas was two in the above embodiment, but it may be one, three or more. Also, the cover resin layer 14 does not need to be formed. Also, the canvas does not need to be impregnated with adhesive. In this case, the canvas becomes relatively softer than when the canvas is impregnated with adhesive, so further noise reduction can be expected.

[0034] The configurations and functions of the above-mentioned embodiments are summarized below. The first of the above-mentioned embodiments is a conveyor belt 1 having a conveying surface and capable of conveying an object to be conveyed that is brought into contact with the conveying surface by being moved in a longitudinal direction, in which canvas 12 is exposed at least on the back surface located on the side opposite to the conveying surface, and the canvas 12 is composed of warp threads 2 arranged along the longitudinal direction and weft threads 3 arranged crossing the warp threads 2, and the conveyor belt 1 has a surface property parameter (Sk) value of 150 or less using a load curve in a square-shaped judgment area with a side of 10 mm or more set on the back surface.

[0035] According to this configuration, the unevenness on the back surface can be made small corresponding to a surface texture parameter (Sk) value of 150 or less, thereby reducing noise caused by the unevenness. Furthermore, the surface texture parameter (Sk) can be measured by a commercially available three-dimensional shape measuring device, so it can be easily used as an evaluation criterion.

[0036] In a second embodiment (subordinate to the first embodiment), the warp yarns 2 may be multifilaments, and the weft yarns 3 may be monofilaments.

[0037] According to this configuration, by using relatively flexible multifilaments for the warp yarns 2, the conveyor belt 1 can be easily bent, for example, to fit around a pulley when attached to a belt conveyor. On the other hand, by using relatively rigid monofilaments for the weft yarns 3, unnecessary deformation of the conveyor belt 1 in the width direction can be suppressed, and the articles to be conveyed can be stably supported.

[0038] In a third of the above embodiments (subordinate to the first or second), the warp threads 2 and the weft threads 3 may be made of polyester.

[0039] According to this configuration, the conveyor belt 1 can be made of a general-purpose material.

[0040] In the fourth embodiment (subject to any of the first to third embodiments), the canvas 12 exposed on the back surface may be impregnated with an adhesive.

[0041] According to this configuration, the widthwise ends of the conveyor belt 1 are fixed with an adhesive, so that the generation of fuzz at the ends can be suppressed.

[0042] According to the embodiment, noise caused by unevenness on the back surface can be reduced, and therefore noise during transportation can be reduced without requiring special manufacturing equipment. [Explanation of symbols]

[0043] 1...conveyor belt, 2...warp thread, 3...weft thread, 4...projection area, 5...recess area, 11...front canvas, 12...back canvas, 13...middle resin layer, 14...cover resin layer, 41...step

Claims

1. A conveyor belt having a conveying surface and capable of conveying an object to be conveyed that is brought into contact with the conveying surface by being moved in a longitudinal direction, At least the canvas is exposed on the back surface located on the opposite side to the conveying surface, The canvas is The fabric is made up of warp yarns arranged along the longitudinal direction and weft yarns arranged to cross the warp yarns, The conveyor belt has a surface quality parameter (Sk) value of 150 or less using a load curve in a square judgment area having one side of 10 mm or more set on the back surface.

2. 2. The conveyor belt according to claim 1, wherein the warp yarns are multifilaments and the weft yarns are monofilaments.

3. 2. The conveyor belt according to claim 1, wherein the warp threads and the weft threads are made of polyester.

4. The conveyor belt according to claim 1 , wherein the canvas exposed on the back surface is impregnated with an adhesive.

Images