Conveyance belt

Abstract

Provided is a conveyance belt capable of suppressing deformation of a through-hole more than before. A conveyance belt 14 comprises: a woven fabric; an elastic layer 25 made of a first thermoplastic material provided on an upper surface of the woven fabric; and a surface resin layer 22 provided on an upper surface of the elastic layer 25 and made of a second thermoplastic material having hardness lower than that of the first thermoplastic material. The woven fabric, the elastic layer 25, and the surface resin layer 22 have a plurality of through-holes 20 which penetrate through the thickness of the woven fabric, the elastic layer 25, and the surface resin layer 22, and which suck air to suck and hold a workpiece 11 placed on the surface resin layer 22. The conveyance belt 14 is configured such that by selecting the thickness of the surface resin layer 22 and the distance between the outer edges of the adjacent through-holes 20, the expansion of the through-hole 20 in the surface direction is suppressed by the elastic layer 25 when the abrasion of the surface resin layer 22 progresses by the brush and the through-hole 20 spreads in the surface direction of the surface resin layer 22.

Description

Conveyor belt

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

[0002] A known example of a polishing device is a deburring device that removes burrs from a workpiece (see, for example, Patent Document 1). In the deburring device, a workpiece having burrs formed on its upper surface is transported by a conveyor belt, and a rotating roll-shaped brush contacts the workpiece from above. This removes the burrs from the workpiece. The conveyor belt used in the deburring device (hereinafter referred to as the conveyor belt for the deburring device or simply the conveyor belt) is an endless belt with joined ends. Multiple brushes are provided at positions that equally divide a rotation plane centered on an axis perpendicular to the conveying surface of the conveyor belt. Each of the multiple brushes rotates around a horizontal axis, and multiple brushes also rotate around an orthogonal axis, thereby pressing the multiple brushes against the surface of the workpiece from various directions.

[0003] The conveyor belt has a plurality of through holes (penetrating holes) that penetrate the thickness of the conveyor belt from the conveying surface to the backside, and a vacuum device sucks air from the backside of the conveyor belt through the plurality of through holes to generate negative pressure. The workpieces are conveyed while being sucked onto the conveying surface.

[0004] A known conveyor belt is composed of at least two layers: a core layer made of woven fabric and an elastic surface resin layer (see, for example, Patent Document 2). The core layer is harder than the surface resin layer. The surface resin layer is made of, for example, polyurethane (PU) or polyvinyl chloride (PVC) softened by adding a plasticizer, thereby increasing adhesion and ensuring high friction on the conveying surface.

[0005] When the surface resin layer is made of soft polyurethane (PU) softened by adding a plasticizer, the adhesiveness becomes strong. When forming through holes in a conveyor belt having a soft PU surface resin layer, the surface resin layer must be thick enough to tolerate abrasion by a brush. Here, 1001 in FIG. 8 shows a cross section of the conveyor belt 100 in its initial state, for example. As shown in FIG. 8, 1001 indicates the conveyor belt 100, which includes a surface resin layer 102 having a thickness T1 (e.g., 5 mm) and a resin layer 101 having a thickness T2 (e.g., 2.5 mm) below the surface resin layer 102. The conveyor belt 100 is provided with a plurality of through holes 103 having a diameter φA, penetrating the thickness of the belt.

[0006] JP 2013-107139 A Japanese Patent No. 7228953 A

[0007] However, as shown in 1002 in FIG. 8 , when a workpiece 104 placed on the surface resin layer 102 is polished by a brush of a deburring device (not shown), the brush also polishes and wears the conveying surface 102a of the surface resin layer 102. When the surface resin layer 102 is worn, the through-holes 103 may widen in the thickness direction of the surface resin layer 102 or in the direction of the conveying surface 102a. In this case, for example, a funnel opening 105 having an inverted truncated cone shape may be formed at the opening of the through-hole 103 on the conveying surface 102a side due to polishing by the brush. For example, the funnel opening 105 may be worn into a large-diameter circle on the conveying surface 102a side, and the diameter gradually decreases in the thickness direction, eventually forming an inverted truncated cone shape that connects to the original diameter of the through-hole 103.

[0008] With long-term use of the conveyor belt 100, the funnel openings 105 of the through holes 103 on the conveying surface 102a side are worn in the thickness direction and also widen in the surface direction. As a result, adjacent funnel openings 105 may connect with each other on the conveying surface 102a. If adjacent through holes 103 connect with each other on the conveying surface 102a, negative pressure may leak, weakening the suction of the workpiece 104 and potentially reducing the holding force of the workpiece 104 required for deburring with a brush. Therefore, a conveyor belt used in a deburring device is desired to have a configuration that can prevent deformation of the through holes 103. Furthermore, in a polishing device that uses a brush to polish the surface of the workpiece 104 for purposes other than deburring, such as simple polishing, the conveying surface of the conveyor belt on which the workpiece 104 is placed is also polished by the brush, as described above. Therefore, a conveyor belt used in various other polishing devices is also desired to have a configuration that can prevent deformation of the through holes.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a conveyor belt that can suppress deformation of the through holes more than ever before.

[0010] The conveying belt according to the present invention is a conveying belt that is installed in a polishing device that polishes the surface of a workpiece with a brush, and that sucks and holds the workpiece and transports it to the brush. The conveying belt comprises a woven fabric, an elastic layer made of a first thermoplastic material that is installed on the upper surface of the woven fabric, and a surface resin layer that is installed on the upper surface of the elastic layer and is made of a second thermoplastic material that is lower in hardness than the first thermoplastic material. The woven fabric, elastic layer, and surface resin layer have a plurality of through holes that penetrate the thickness of the woven fabric, elastic layer, and surface resin layer and suck air to suck and hold the workpiece placed on the surface resin layer. By selecting the thickness of the surface resin layer and the distance between the outer edges of adjacent through holes, when the surface resin layer is worn away by the brush and the through holes expand in the surface direction of the surface resin layer, the elastic layer can suppress the expansion of the through holes in the surface direction.

[0011] According to the conveying belt of the present invention, even if the surface resin layer is worn away by the brush and the through holes widen, the elastic layer can suppress the widening of the through holes, and therefore deformation of the through holes can be suppressed more than before.

[0012] 10 is a side view showing the configuration of a deburring device; 1001 is a plan view showing the configuration of a plurality of through holes formed in a conveyor belt; 1002 is a cross-sectional view showing the cross-sectional configuration of a conveyor belt; 1003 is a plan view showing the configuration of through holes in an initial state when the conveyor surface is viewed from above; 1004 is a cross-sectional view showing deformation of through holes in a conveyor belt of this embodiment in time series, where 1011 is a cross-sectional view showing the initial state of the through holes, 1012 is a cross-sectional view showing the state of the through holes when the conveyor belt is polished by a brush, and 1013 is a cross-sectional view showing the state of the through holes when the conveyor belt is polished by a brush over a long period of time; 1005 is a cross-sectional view showing the cross-sectional configuration (1) of a conveyor belt according to another embodiment; 1006 is a cross-sectional view showing the cross-sectional configuration (2) of a conveyor belt according to another embodiment; 1007 is a cross-sectional view showing deformation of through holes that occurs in a conventional conveyor belt, where 1001 is a cross-sectional view showing the initial state of the through holes, and 1002 is a cross-sectional view showing the state of the through holes when the conveyor belt is polished by a brush over a long period of time.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification and the drawings, substantially identical components are designated by the same reference numerals, and redundant description will be omitted.

[0014] 1. Overview of the Deburring Device As shown in Fig. 1, a deburring device 10 includes a belt conveyor 12 that transports a workpiece 11 in a transport direction and a brush mechanism 13 that polishes the surface of the workpiece 11. The brush mechanism 13 is disposed above the belt conveyor 12. The brush mechanism 13 includes a plurality of brushes 131 and a support shaft 132 on which each brush 131 is rotatably mounted. The brush mechanism 13 according to this embodiment has a configuration in which, for example, four brushes 131 are arranged to extend radially (in a cross shape) around the support shaft 132 in a top view of a transport surface 14a of a transport belt (a transport belt for the deburring device, which will be described later and will be simply referred to as the transport belt) 14.

[0015] The support shaft 132 is disposed with its axial direction aligned with the surface normal to the conveying surface 14a of the conveyor belt 14. The brushes 131 are rotatably mounted on the peripheral surface at the tip end of the support shaft 132. The support shaft 132 is rotatably mounted in the circumferential direction around the axial direction. As a result, the support shaft 132 rotates in the circumferential direction, causing the brushes 131 extending radially from the peripheral surface to revolve.

[0016] Since each brush 131 has the same configuration, the following description will focus on one brush 131. The brush 131 is roll-shaped and rotates around a shaft (core member) 13a. The brush 131 has a configuration in which countless brush bristles are planted in a roll around the core member 13a, for example. While rotating, the brush 131 comes into contact from above with the workpiece 11 placed on the conveyor belt 14 of the belt conveyor 12. In this way, the brush 131 polishes the top surface of the workpiece 11 and removes burrs on the top surface.

[0017] In this way, in the deburring device 10, the multiple brushes 131 revolve around the support shaft 132, and each brush 131 rotates independently. This allows the deburring device 10 to polish the surface of the workpiece 11 placed on the conveyor belt 14 with the brushes 131 from various directions, thereby scraping off burrs on the surface of the workpiece 11.

[0018] The workpiece 11 may be, for example, a metal plate that has been punched. The workpiece 11 may also be a substantially plate-shaped member that has been punched into a desired shape by blanking (outline punching / punching), and may be a member made of paper, resin, metal, or non-ferrous metal with a predetermined rigidity. Burrs are protrusions or thorns (burrs) that occur when processing materials such as metal, non-ferrous metal, resin, wood, and paper. The workpiece 11 has such burrs, for example, on its top surface, side surface, holes formed in the surface, surface edges, etc.

[0019] The belt conveyor 12 is composed of a conveyor belt 14, a drive roller 15, a driven roller 16, a suction device 18, etc. The endless conveyor belt 14 is wound around the drive roller 15 and the driven roller 16. The drive roller 15 is driven to rotate, causing the conveyor belt 14 to rotate between the drive roller 15 and the driven roller 16, and transporting the workpieces 11 placed on the transport surface 14a of the conveyor belt 14 in the transport direction.

[0020] The suction device 18 is disposed so as to face the brush 131 across the conveyor belt 14. More specifically, the suction device 18 is disposed on the belt back surface 14b of the conveyor belt 14, which passes through the outward path (conveyance side) that comes into contact with the brush 131. The suction device 18 generates negative pressure by sucking air from the conveyance surface 14a side to the belt back surface 14b side through a plurality of through holes (described later) formed in the conveyor belt 14. As a result, the workpiece 11 is adsorbed to the conveyance surface 14a of the conveyor belt 14. The workpiece 11 is conveyed while being adsorbed and held by the conveyor belt 14, and passes under the rotating brush 131. As the workpiece 11 passes under the rotating brush 131, the surface of the workpiece 11 is polished by the brush 131.

[0021] 2. Structure of the Conveyor Belt for the Deburring Device <Overall Structure of the Conveyor Belt for the Deburring Device> Next, the overall structure of the conveyor belt 14 will be described. As shown in Fig. 3, the conveyor belt 14 includes a core layer 23 as a lower layer, and a surface resin layer 22 provided as a cover layer (upper layer) for the core layer 23. The core layer 23 has a structure in which a first elastic layer 25, a first woven fabric 24, a second elastic layer 26 as an additional elastic layer, a second woven fabric 27 as an additional woven fabric, a third elastic layer 28 as an additional elastic layer, and a third woven fabric 29 as an additional woven fabric are layered in this order from the lower surface of the surface resin layer 22.

[0022] In this example, the core layer 23 is configured as a three-layer laminate, each consisting of an elastic layer and a woven fabric layer provided on its underside. The first woven fabric 24, the second woven fabric 27, and the third woven fabric 29 have a different warp and weft weaving method than knitted fabrics, and do not have the same stretchability as knitted fabrics. In this example, the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29 are described as having the same woven fabric configuration, but the present invention is not limited to this. For example, different types of woven fabrics may be used, such as by changing the warp and weft materials of the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29, or by changing the thicknesses of the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29.

[0023] The first elastic layer 25 is provided on the first woven fabric 24, the second elastic layer 26 is provided on the lower surface of the first woven fabric 24, the second woven fabric 27 is provided on the lower surface of the second elastic layer 26, the third elastic layer 28 is provided on the lower surface of the second woven fabric 27, and the third woven fabric 29 is provided on the lower surface of the third elastic layer 28. The first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 are made of a first thermoplastic material. Note that, although the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 are described as having the same elastic layer configuration, the present invention is not limited thereto, and the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 may be made of different thermoplastic materials, or the thicknesses of the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 may be different. The surface resin layer 22 is made of a second thermoplastic material having a lower hardness (JIS-A) than the first thermoplastic material, and the surface on which the workpiece 11 is placed is a smooth transport surface 14a.

[0024] The conveyor belt 14 is formed with a plurality of through holes 20 at predetermined intervals, penetrating the thickness from the conveying surface 14a to the belt back surface 14b. As shown in FIG. 2 , the through holes 20, which penetrate the thickness of the surface resin layer 22 and the core layer 23, have a substantially circular opening when viewed from above the conveying surface 14a. The shape of the through holes 20 viewed from above the conveying surface 14a may be elliptical, triangular, rectangular, or other shapes instead of circular. In this embodiment, for example, the plurality of through holes 20 are arranged in a staggered pattern. Here, the staggered pattern refers to, for example, a configuration in which, in rows of a plurality of through holes 20 aligned in the width direction, the positions of the through holes 20 in adjacent rows of a plurality of through holes 20 are shifted relative to each other in the conveying direction, so that the through holes 20 are arranged alternately in the conveying direction. The through holes 20 may be arranged in a matrix at predetermined intervals, or in various other patterns. In this embodiment, a case where a plurality of through holes 20 having the same configuration is provided will be described, but the present invention is not limited to this, and a plurality of through holes 20 having different opening shapes such as circular, elliptical, triangular, rectangular, etc. Details of the through holes 20 will be described later.

[0025] <Woven Fabric> In this embodiment, the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29 are woven fabrics of the same configuration. Therefore, to avoid repetition, the following description will mainly focus on the first woven fabric 24. When no particular distinction is made between the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29, these will be referred to individually or collectively as simply "woven fabrics." The first woven fabric 24 is not particularly limited as long as it is obtained by weaving fibers. The weave of the first woven fabric 24 may be any weave, such as a plain weave or a twill weave. The fibers forming the first woven fabric 24 may be selected from, for example, polyester fiber, nylon fiber, aramid fiber, glass fiber, cotton thread, etc. The fibers used for the first woven fabric 24 may be one type or two or more different types.

[0026] Because the conveyor belt 14 uses woven fabric, unlike knitted fabric, it has substantially no stretchability in the conveying direction, and is therefore different in configuration from an elastic belt that has stretchability and elasticity. The thickness of the fibers forming the first woven fabric 24 is not particularly limited, and is, for example, approximately 20 to 280 T (decitex). The thickness of the first woven fabric 24 is preferably approximately 0.3 to 0.8 mm, and more preferably approximately 0.4 to 0.6 mm. The second woven fabric 27 and the third woven fabric 29 may have the same configuration as the first woven fabric 24, or may have a different configuration.

[0027] <Elastic Layer> In this embodiment, the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 have the same configuration. Therefore, to avoid duplication, the following description will focus primarily on the first elastic layer 25. When the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 are not particularly distinguished from one another, they will be referred to individually or collectively as "elastic layers." The first elastic layer 25 is formed from a first thermoplastic material and provides flexibility and strength to the conveyor belt 14. Examples of the first thermoplastic material include thermoplastic elastomers made of polyurethane, polyolefins such as polyethylene and polypropylene, and polyester. Polyurethane elastomers are particularly preferred due to their excellent processability and high strength. The thickness of the first elastic layer 25 is preferably approximately 0.2 to 1.5 mm, and more preferably approximately 0.3 to 0.8 mm. The second elastic layer 26 and the third elastic layer 28 may have the same configuration as the first elastic layer 25 or may have different configurations.

[0028] <Surface Resin Layer> The surface resin layer 22 is composed of a second thermoplastic material having a lower hardness (JIS-A) than the first thermoplastic material. The surface of the surface resin layer 22 opposite the first elastic layer 25 is the conveying surface 14a, which is flat. Because the conveying surface 14a of the surface resin layer 22 is flat, gaps are less likely to form between the workpiece 11 and the through-holes 20. This allows for greater suction force from the through-holes 20 to be applied to the workpiece 11, ensuring that the workpiece 11 is securely held by suction against the conveying surface 14a. Because the surface resin layer 22 is composed of a thermoplastic material, it has excellent abrasion resistance. The second thermoplastic material may be, for example, a mixture of the first thermoplastic material and the additives described below. A preferred second thermoplastic material is a resin such as low-hardness polyurethane having a hardness (JIS-A) of 70 or less.

[0029] The thickness T1 of the surface resin layer 22 is preferably approximately 0.2 to 2.5 mm, and more preferably approximately 0.3 to 0.8 mm. The thickness T1 of the surface resin layer 22 is preferably selected taking into consideration the distance between the outer edges of adjacent through holes 20 formed in the conveyor belt 14 and the abrasion deformation of the through holes 20 caused by the brushes 131. Specifically, the thickness T1 of the surface resin layer 22 and the distance between the outer edges of adjacent through holes 20 are preferably selected so that when the surface resin layer 22 is worn down by the brushes 131 over a long period of use of the conveyor belt 14, the first elastic layer 25, which has a high hardness and is located directly below the surface resin layer 22, suppresses abrasion of the through holes 20 in the thickness direction, thereby preventing the worn through holes 20 from connecting with each other on the conveyor surface 14a. Details will be described later.

[0030] <Configuration of Through Holes> In the initial state when the conveyor belt 14 has not yet been polished by the brush 131, the through holes 20 are configured to penetrate through the thicknesses of the surface resin layer 22, the first elastic layer 25, the first woven fabric 24, the second elastic layer 26, the second woven fabric 27, the third elastic layer 28, and the third woven fabric 29, with approximately the same opening area. The through holes 20 allow the suction device 18 to suck air from the belt back surface 14b to the conveyor surface 14a, and the workpiece 11 placed on the surface resin layer 22 is suctioned and held by the suction of air by the suction device 18. For example, the ratio of the through holes 20 to the total area of ​​the conveyor surface 14a (opening rate) is 1 to 50%, preferably 1 to 20%.

[0031] Fig. 4 is a plan view showing the configuration of the through holes 20 in an initial state when viewed from above the conveying surface 14a. In Fig. 4, the diameter of the through holes 20 is φA, and the center-to-center distance (conveying direction distance) between adjacent through holes 20 in the conveying direction, including different rows, is shown as P1. Also in Fig. 4, the center-to-center distance (width direction distance) between adjacent through holes 20 in the same row in the width direction is shown as P2. Furthermore, in Fig. 4, the minimum distance between the centers of the closest through holes 20 is shown as R, and the distance (minimum distance) between the outer edges of the closest through holes 20 is shown as L.

[0032] In the conveyor belt 14 in which the distance L between the outer edges of adjacent through holes 20 is shortened, the number of areas where the workpieces 11 are attracted increases, thereby increasing the suction holding power of the workpieces. However, this poses the problem of shortening the lifespan of the belt 14 due to wear of the through holes 20 by the brushes 131, which makes it easier for adjacent through holes 20 to connect with each other.

[0033] On the other hand, in the conveyor belt 14 in which the distance L between the outer edges of adjacent through holes 20 is increased, the adjacent through holes 20 are less likely to be connected to each other due to wear of the through holes 20 caused by the brushes 131, and therefore the lifespan of the conveyor belt 14 is extended. However, there is a problem in that the suction force for the workpiece 11 is reduced because the number of points for adsorbing the workpiece 11 is reduced.

[0034] In this embodiment, it is desirable to select the distance L between the outer edges of adjacent through holes 20 so as to increase the number of points where the workpiece 11 is adsorbed and thereby increase the suction holding force of the workpiece, and to select the thickness T1 of the surface resin layer 22 so that the first elastic layer 25 prevents the through hole 20 from expanding in the thickness direction and surface direction.

[0035] The thickness T1 of the surface resin layer 22 is desirably less than the distance L between adjacent through holes 20 (i.e., T1<L). For example, when the thickness T1 of the surface resin layer 22 is 2.5 mm or less, the diameter φA of the through holes 20 is desirably 2 to 8 mm, desirably 2 to 5 mm, the minimum distance R between the centers of the nearest through holes 20 is desirably 15 to 40 mm, desirably 20 to 30 mm, and the minimum distance L between the outer edges of the nearest through holes 20 is desirably 10 to 30 mm, desirably 20 to 30 mm.

[0036] Furthermore, for example, when the thickness T1 of the surface resin layer 22 is 2.5 mm or less, the center-to-center distance (conveyance direction distance) P1 between adjacent through holes 20 in the conveyance direction, including different rows, is 10 to 30 mm, preferably 20 to 30 mm, and the center-to-center distance (width direction distance) P2 between adjacent through holes 20 in the same row in the width direction is 15 to 40 mm, preferably 20 to 30 mm.

[0037] <Static Friction Coefficient> The static friction coefficient of the conveying surface 14a of the surface resin layer 22 of the conveyor belt 14 is preferably 0.5 to 1.0. By making the surface resin layer 22 from the second thermoplastic material, a static friction coefficient within a predetermined range can be ensured. If the static friction coefficient of the conveying surface 14a is 0.5 or higher, the workpiece 11 can be reliably conveyed even when the conveyor belt 14 is installed at an angle, without suction and holding via the through holes 20 by the suction device 18. Considering the high friction coefficient required for object conveyance, the upper limit of the static friction coefficient of the conveyor belt 14 is preferably set to 1.0. The static friction coefficient is preferably 0.6 or higher, and more preferably 0.7 or higher.

[0038] The static friction coefficient is measured using a surface property measuring instrument (manufactured by Shinto Scientific Co., Ltd.). The conveyor belt 14 is a test piece of 20 mm x 30 mm, and cardboard is used as the object. The test piece is placed on the cardboard and moved at a speed of 5 mm / min while applying a load of 0.8 kPa to the test piece to determine the static friction coefficient.

[0039] 3. Degree of Deformation of Through Holes Due to Long-Term Use Next, the use state of the conveyor belt 14 of this embodiment will be described with reference to Fig. 5 . Here, of the surface resin layer 22 and the core layer 23 of the conveyor belt 14, the following description focuses on the surface resin layer 22 and the first elastic layer 25 located directly below the surface resin layer 22. In Fig. 4 , the first woven fabric 24, the second elastic layer 26, the second woven fabric 27, the third elastic layer 28, and the third woven fabric 29 in the core layer 23 are omitted from illustration. In the initial state, as indicated by 1011 in Fig. 5 , the diameter of the through holes 20 penetrates the thickness of the surface resin layer 22 and the first elastic layer 25 with approximately the same diameter.

[0040] 5, for example, the thickness of the surface resin layer 22 is represented as T1, the thickness of the first elastic layer 25 is represented as T2, the diameter of the through hole 20 is represented as φA, the distance between the outer edges of adjacent through holes 20 is represented as L, and the distance between the centers of adjacent through holes 20 is represented as R. For example, the thickness T1 of the surface resin layer 22 is selected to be less than the distance L between the outer edges of adjacent through holes 20 (T1<L).

[0041] As the conveyor belt 14 is used in the deburring device 10, the outer edges of the through holes 20 exposed to the conveying surface 14a are worn away by the abrasion caused by the brush 131. As a result, as shown by 1012 in FIG. 5 , the surface openings 34a of the through holes 20 on the conveying surface 14a side widen in the planar direction, and the surface openings 34a are also worn away in the thickness direction. By being abraded by the brush 131, the diameter of the surface openings 34a of the through holes 20 becomes larger than the initial diameter. As a result, for example, a funnel opening 34 having an inverted truncated cone shape may be formed at the surface openings 34a of the through holes 20 in the surface resin layer 22. The diameter of the funnel opening 34a gradually decreases as it approaches the first elastic layer 25 from the conveying surface 14a. The funnel opening 34 has an inverted truncated cone shape that connects a surface opening 34a and a small-diameter opening 34b, which has a smaller diameter than the surface opening 34a and is closer to the first elastic layer 25, by an inclined surface.

[0042] As the conveyor belt 14 continues to be used in the deburring device 10, the surface openings 34a on the conveying surface 14a side are polished by the brush 131, further abrading the funnel openings 34 of the through holes 20, and the diameter of the funnel openings 34 increases, as indicated by 1013 in FIG. 5 . The first elastic layer 25, provided as a lower layer of the surface resin layer 22, is made of a first thermoplastic material having a harder hardness (JIS-A) than the surface resin layer 22. Therefore, wear of the through holes 20 progresses at the surface resin layer 22, and when the small-diameter openings 34b of the funnel openings 34 reach the first elastic layer 25, the first elastic layer 25 suppresses the progression of wear of the small-diameter openings 34b. Since the first elastic layer 25 suppresses the progression of wear in the thickness direction at the funnel openings 34 of the surface resin layer 22, wear in the surface direction (toward the conveying surface 14a) accompanying the progression of wear in the thickness direction is also suppressed accordingly.

[0043] Therefore, even if the conveyor belt 14 is used for a long period of time in the deburring device 10, the first elastic layer 25 directly below the surface resin layer 22 can suppress the expansion of the through holes 20 in the surface direction, thereby suppressing deformation of the through holes 20 that would cause adjacent through holes 20 to communicate with each other. In this way, by selecting the thickness T1 of the surface resin layer 22 and the distance L between the outer edges of adjacent through holes 20, the conveyor belt 14 is less likely to deform than the through holes 103 of the conventional conveyor belt 100 described in Figure 8.

[0044] 4. Manufacturing Method of Conveyor Belt for Deburring Device The following describes a manufacturing method of the conveyor belt 14. The conveyor belt 14 can be manufactured by any method as long as the first elastic layer 25, the first woven fabric 24, the second elastic layer 26, the second woven fabric 27, the third elastic layer 28, and the third woven fabric 29 are fixed together and the first elastic layer 25 and the surface resin layer 22 are fixed together so that they do not peel off.

[0045] First, a thermoplastic sheet that will become the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28 is produced using a predetermined thermoplastic elastomer using a calendar or extrusion device. The size of the sheet is adjusted to the size of the woven fabrics (first woven fabric 24, second woven fabric 27, and third woven fabric 29). The sheet can be fixed to the first woven fabric 24, second woven fabric 27, and third woven fabric 29 using rubber cement.

[0046] The woven fabrics (here, the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29) are pre-impregnated with rubber cement. The rubber cement can be impregnated into the woven fabrics using an application means such as a coater or a brush. Alternatively, the woven fabrics may be immersed in the rubber cement to impregnate the woven fabrics with the rubber cement.

[0047] The third elastic layer 28, the second woven fabric 27 impregnated with rubber cement, the second elastic layer 26, the first woven fabric 24 impregnated with rubber cement, and the first elastic layer 25 are placed in this order on the third woven fabric 29 impregnated with rubber cement, and then bonded together under heat and pressure. In this way, the core layer 23 is obtained, in which the woven fabrics (the first woven fabric 24, the second woven fabric 27, and the third woven fabric 29) and the elastic layers (the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28) made of the first thermoplastic material are alternately laminated.

[0048] On the other hand, a surface resin layer 22 made of a second thermoplastic material is produced using a predetermined raw material composition. The raw material composition can be prepared, for example, by mixing an ether-based thermoplastic polyurethane elastomer (hereinafter referred to as ether-based TPU) as a first thermoplastic material with a hydrogenated styrene-based thermoplastic elastomer (hereinafter referred to as styrene-based TPE) as an additive, a compatibilizer, and a wax. By using such a raw material composition, a second thermoplastic material having a lower hardness (JIS-A) than the first thermoplastic material can be obtained.

[0049] The proportions of the components in the raw material composition can be, for example, as follows: Ether-based TPU: 50 to 65% by mass Styrene-based TPE: 10 to 30% by mass Compatibilizer: 0 to 10% by mass Wax: 5 to 15% by mass Calcium carbonate: 0 to 25% by mass If necessary, the raw material composition may be prepared by further blending optional components.

[0050] The ether-based TPU may be, for example, an ether-based thermoplastic urethane resin having a hardness equivalent to 80 as measured with a Type A durometer in accordance with Japanese Industrial Standard JIS K6253. The compatibilizer may be a mixture of a hydrogenated styrene-based elastomer and a thermoplastic urethane resin. The wax may be commercially available solid paraffin oil.

[0051] A raw material composition prepared by blending the components in a predetermined ratio is used to produce a resin sheet that will become the surface resin layer 22 using a calendaring device. That is, the molten raw material composition is continuously poured between two rolls arranged at a predetermined distance, while the two rolls are rotated in the same direction to obtain a strip-shaped resin sheet. The size of the resin sheet is adjusted to the size of the woven fabrics (first woven fabric 24, second woven fabric 27, and third woven fabric 29).

[0052] The resulting resin sheet is placed on the first elastic layer 25 of the previously prepared core layer 23 to obtain a laminate. This laminate is laminated during extrusion or processed to a predetermined thickness by heat and pressure bonding after sheet molding. Heat and pressure bonding fixes the first elastic layer 25 of the core layer 23 to the surface resin layer 22.

[0053] In this way, a conveyor belt is obtained in which the surface resin layer 22 is laminated on the core layer 23, which has three layers of woven fabric and elastic layers. Then, by forming a plurality of through holes 20 in the obtained conveyor belt by drilling, the conveyor belt 14 for use in the deburring device 10 can be obtained. The conveyor belt 14 can be processed into an endless shape by joining both ends with finger joints, and can be used in belt conveyors, etc. Alternatively, the conveyor belt 14 can be manufactured by first double-sizing the width, drilling the conveyor belt 14 to open a plurality of through holes 20, and then cutting the width in half to obtain the specified width.

[0054] The static friction coefficient of the conveying surface 14a of the surface resin layer 22 depends on the hardness (JIS-A) of the second thermoplastic material constituting the surface resin layer 22. By adjusting the blending ratio of each component in the raw material composition, the static friction coefficient of the conveying surface 14a can be changed between 0.5 and 1.0. For example, the higher the ratio of styrene-based TPE to ether-based TPU in the raw material composition, the higher the static friction coefficient.

[0055] 5. Function and Effect The conveyor belt 14 according to this embodiment is formed with a plurality of through holes 20 that penetrate the thickness of the woven fabric, the elastic layer, and the surface resin layer 22 and suck in air to hold by suction the workpiece 11 placed on the surface resin layer 22. In addition, the conveyor belt 14 is configured such that, by selecting the thickness T1 of the surface resin layer 22 and the distance L between the outer edges of adjacent through holes 20, when the surface resin layer 22 is worn down by the brushes 131 and the through holes 20 expand in the surface direction of the surface resin layer 22, the first elastic layer 25 suppresses the expansion of the through holes 20 in the surface direction.

[0056] As a result, even if the surface resin layer 22 of the conveying belt 14 is worn away by the brush 131 and the through holes 20 widen, the first elastic layer 25 can prevent the through holes 20 from widening, and therefore deformation of the through holes 20 can be suppressed more than before.

[0057] The conveyor belt 14 according to the present embodiment includes a woven fabric and an elastic layer made of a thermoplastic material provided on the woven fabric. The conveyor belt 14 has sufficient strength due to the inclusion of at least the woven fabric and the elastic layer.

[0058] The surface resin layer 22 provided on the first elastic layer 25 is made of a thermoplastic material having a lower hardness (JIS-A) than the first elastic layer 25, and has a smooth conveying surface 14a. As is generally known, the lower the hardness (JIS-A) of a thermoplastic material, the higher the coefficient of friction. Therefore, the conveying surface 14a of the surface resin layer 22 has a larger static friction coefficient than the conveying surface (surface) of the first elastic layer 25. The static friction coefficient of the conveying surface 14a is in the range of 0.5 to 1.0. The conveying belt 14 according to this embodiment can reliably convey the workpiece 11 even during inclined conveying, even without suction by the suction device 18, and also has sufficient wear resistance.

[0059] In addition, the surface resin layer 22 of the conveyor belt 14 is formed from low-hardness polyurethane, the same polyurethane-based material as the first elastic layer 25, thereby increasing the adhesive strength between the surface resin layer 22 and the first elastic layer 25 and preventing peeling during use. Furthermore, in the conveyor belt 14, the surface resin layer 22 is formed from a low-hardness polyurethane without adding a plasticizer, thereby preventing a decrease in abrasion resistance and preventing adhesion inhibition due to bleeding of the plasticizer. Furthermore, in the conveyor belt 14, the surface resin layer 22 is formed from a second thermoplastic material obtained by mixing a styrene-based TPE as an additive into a first thermoplastic material, thereby achieving abrasion resistance, low hardness, and a high coefficient of friction in the surface resin layer 22.

[0060] Furthermore, in the conveyor belt 14, the thickness T1 of the surface resin layer 22 is set to 2.5 mm or less, and the thickness T1 of the surface resin layer 102 is reduced, thereby enabling the weight of the entire conveyor belt 14 to be reduced. Also, in the conveyor belt 14, elastic layers (the first elastic layer 25, the second elastic layer 26, and the third elastic layer 28) having a higher hardness (JIS-A) than the surface resin layer 22 and exceeding 70 are provided in the core layer 23. This allows the conveyor belt 14 to maintain its overall strength, as well as the strength of the joints when both ends are joined to form an endless belt.

[0061] 6. Other Embodiments The present invention is not limited to the embodiments described herein, and can be modified appropriately within the scope of the present invention.

[0062] In the above-described embodiment, the core layer 23 has a three-layer structure of a woven fabric and an elastic layer, in which the first elastic layer 25, the first woven fabric 24, the second elastic layer 26, the second woven fabric 27, the third elastic layer 28, and the third woven fabric 29 are laminated as a core layer having an elastic layer on the upper surface of the woven fabric. However, the present invention is not limited to this. As another conveyor belt, for example, as shown in Fig. 6, a conveyor belt 14A may be used which includes a core layer 23A in which the first woven fabric 24 and the first elastic layer 25 are laminated and fixed in this order on the second elastic layer 26.

[0063] In this case, the core layer 23A has a first elastic layer 25 and a second elastic layer 26, which are elastic layers, provided on both the front and back surfaces of a first woven fabric 24, which is a woven fabric, and a surface resin layer 22 provided on one of the first elastic layers 25. Similarly to the above-described embodiment, the conveyor belt 14A also has a plurality of through holes 20 formed therethrough to penetrate the thickness. The second thermoplastic material used for the second elastic layer 26 may be the same as or different from the first thermoplastic material used for the first elastic layer 25. The second thermoplastic material is not limited to being a mixture of the first thermoplastic material and an additive, but may also be a mixture of a thermoplastic material different from the first thermoplastic material and an additive.

[0064] 7, a conveyor belt 14B may be used, which includes a core layer 23B having a single-layer structure of a woven fabric and an elastic layer, in which a first elastic layer 25 and a first woven fabric 24 are laminated together. The core layer 23B has a surface resin layer 22 provided on the first elastic layer 25. The conveyor belt 14B also has a plurality of through holes 20 formed therethrough, similar to the above-described embodiment. Even with this configuration, the same effects as those of the conveyor belt 14 of the above-described embodiment can be achieved.

[0065] In the above-described embodiment, the conveyor belts 14, 14A, and 14B used in the deburring device 10, which polishes the surface of a workpiece 11 with a brush 131 to remove burrs from the workpiece 11, have been described as conveyor belts used in a polishing device that polishes the surface of a workpiece with a brush. However, the present invention is not limited to this. For example, the conveyor belts may be used in various polishing devices that perform other surface processing, such as polishing the surface of a workpiece with a brush, rather than deburring. Note that, like the conveyor belts 14, 14A, and 14B described above, the conveyor belts for such polishing devices also suction-hold the workpiece on the conveying surface by suctioning air through the through holes and transporting the workpiece to the brushes of the polishing device. By selecting the thickness T1 of the surface resin layer and the distance L between the outer edges of adjacent through holes in the same manner as in the above-described embodiment, the conveyor belts for polishing devices can also be configured to have an elastic layer that suppresses the expansion of the through holes in the surface direction when the surface resin layer is worn down by the brush and the through holes expand in the surface direction of the surface resin layer.

[0066] 10 Deburring device (polishing device) 11, 104 Workpiece 14, 14A, 14B, 100 Conveyor belt (conveyor belt for deburring device, conveyor belt for polishing device) 14a, 102a Conveyor surface 18 Suction device 20, 103 Through hole 22, 102 Surface resin layer 24 First woven fabric (woven fabric) 25 First elastic layer (elastic layer) 26 Second elastic layer (additional elastic layer) 27 Second woven fabric (additional woven fabric) 28 Third elastic layer (additional elastic layer) 29 Third woven fabric (additional woven fabric) 34, 105 Funnel opening 131 Brush

Claims

1. A conveyor belt that is installed in a polishing device that polishes the surface of a workpiece with a brush, and that suction-holds the workpiece and transports it to the brush, comprising: a woven fabric; an elastic layer made of a first thermoplastic material provided on an upper surface of the woven fabric; and a surface resin layer made of a second thermoplastic material having a hardness lower than that of the first thermoplastic material, the woven fabric, the elastic layer, and the surface resin layer having a plurality of through holes that penetrate through the thicknesses of the woven fabric, the elastic layer, and the surface resin layer and suck in air to hold the workpiece placed on the surface resin layer, and the thickness of the surface resin layer and the distance between the outer edges of adjacent through holes are selected so that when the surface resin layer is worn away by the brush and the through holes expand in the surface direction of the surface resin layer, the elastic layer suppresses the expansion of the through holes in the surface direction.

2. A conveyor belt as described in claim 1, wherein when the through holes in the surface resin layer are worn in the thickness direction by the brush, the elastic layer suppresses wear of the through holes in the thickness direction and suppresses expansion of the through holes in the surface resin layer in the planar direction.

3. The conveyor belt according to claim 1, which is endless with both ends joined, and the through holes are formed at predetermined intervals.

4. The transport belt of claim 1 further comprising an additional elastic layer of thermoplastic material on the lower surface of said woven fabric.

5. The conveyor belt according to claim 4, further comprising an additional woven fabric provided in contact with the lower surface of said additional elastic layer.

6. A conveyor belt according to any one of claims 1 to 5, wherein the polishing device is a deburring device that polishes the surface of the workpiece with the brush to remove burrs from the surface.

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