Tension applying device for a metal mesh belt

Abstract

Provided is a tension applying device for a metal mesh belt that maintains an appropriate tension applied to the metal mesh belt and can easily and accurately equalize the tension in the width direction of the belt. 【Solution means】The tension applying device 10 includes a pair of moving mechanisms 20 that hold the driven roller 4 so as to be able to approach and separate from the driving roller 3, and a pair of biasing force generating mechanisms 30 that bias the driven roller 4 in a direction away from the driving roller 3. The moving mechanism 20 is composed of bearings 21 provided at both ends of the driven roller 4, and an upper slide member 23 and a lower slide member 24 that hold the bearings 21. The biasing force generating mechanism 30 is composed of an air spring 31, a fixing member 32 that fixes the air spring 31 to the frame 2, and a connecting member 35 that connects the air spring 31 and the bearing 21. By making the pressure of the compressed air stored inside the air springs 31 of the pair of biasing force generating mechanisms 30 the same, the tension applied to the metal mesh belt 5 is equalized in the width direction.

Description

Technical Field

[0001] The present invention relates to a tension applying device for a metal mesh belt in a belt conveyor that loads and continuously conveys loose materials such as raw materials (conveyed materials) on an endless metal mesh belt.

Background Art

[0002] In a belt conveyor that loads and continuously conveys loose materials such as raw materials (conveyed materials), the belt is looped around a driving roller and a driven roller, and the conveyed material is loaded on this belt and conveyed from the driven roller side toward the driving roller side.

[0003] For example, in a belt conveyor used in a food steamer or cooler, when the conveyed material becomes hot or when it is necessary to ventilate and cool the conveyed material, a metal mesh belt formed of a stainless steel wire mesh or a steel belt having through holes formed therein is selected. The metal mesh belt can configure the device more compactly than the steel belt and is widely used because it is inexpensive. Therefore, it was decided to study a device for applying tension specialized for the metal mesh belt.

[0004] When the temperature of the metal mesh belt changes during operation, such as in a steamer or cooler, thermal expansion and contraction of the belt occur and the tension of the belt fluctuates. When the tension of the belt weakens, the frictional force between the belt and the driving roller decreases, causing the belt to slip and unable to convey the conveyed material. Also, if the degree of thermal expansion and contraction differs in the width direction of the belt, a difference in tension occurs in the width direction of the belt, causing the belt to meander. Furthermore, when the difference in tension in the width direction of the belt becomes large, the mesh structure of the metal mesh belt may be permanently deformed partially. Therefore, in the metal mesh belt, it is necessary to maintain an appropriate belt tension and equalize the tension in the width direction of the belt.

[0005] Regarding the application of tension to a metal mesh belt, Patent Document 1 discloses that the driven roller 52 is axially movable by a tensioner 55, and a predetermined tension is applied to the conveyor 4 by moving the driven roller 52 (paragraph

[0021] ). According to FIG. 1 of the same document, the tensioner 55 is presumed to be an air cylinder or a hydraulic cylinder.

[0006] Patent Document 2 discloses that the outer peripheral surface of the belt 1 is pressed in a substantially normal direction by a tension roller 6, and the tension of the belt 1 is maintained by the tension roller 6 (paragraph

[0011] , FIGS. 6 and 7). That is, the tension roller 6 applies a force along the substantially normal direction of the belt while maintaining a constant distance between the driving roller and the driven roller to apply tension to the belt. Although the type of the belt is not described, conventionally, a mechanism similar to the tension adjusting device described in Patent Document 2 has also been adopted for metal mesh belts.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, when using an air cylinder or a hydraulic cylinder as in the tension applying device for a metal mesh belt described in Patent Document 1, since the pushing direction and the pressing surface of the cylinder are strictly determined, high precision is required for the manufactured parts, resulting in an increase in cost. Further, if an assembly error occurs and the cylinder presses while being slightly tilted, there is a possibility that the expected biasing force cannot be applied.

[0009] Furthermore, if the state where the cylinder is pressed while being slightly tilted continues, uneven wear of the piston packing and rod packing due to a lateral load, that is, a load in a direction intersecting the expansion and contraction direction, will occur, and eventually air or oil leakage will occur. Among the pair of cylinders provided on the shaft of the driven roller, if the biasing force applied to one of them decreases, a difference in biasing force will occur in the width direction, causing the belt to meander. If the difference in biasing force becomes even larger, the mesh structure of the belt may deform.

[0010] In view of the fact that in the tension applying device described in Patent Document 2, cases where the belt 118 is cut due to a decrease in the stiffness of the belt 118 caused by temperature changes occur relatively frequently, a system that is easy to replace is disclosed (paragraphs

[0006] ,

[0008] ). However, the configuration in which the belt 1 is bent inward by the two tension rollers 6 to maintain the tension (paragraph

[0011] , FIGS. 6 and 7) has a high possibility of shortening the life of the belt because the bending and friction points of the belt 1 increase compared to a configuration without tension rollers. Also, the device configuration becomes complicated, and it is assumed that it takes time to adjust the tension.

[0011] The present invention solves the conventional problems of an increase in cost caused by the use of cylinders as described above, and meandering and deformation of the mesh structure caused by the difference in the tension in the width direction of the tension applied to the metal mesh belt, and can extend the life of the belt. That is, an object of the present invention is to provide a tension applying device for a metal mesh belt that can accurately and easily equalize the tension applied to the metal mesh belt in the width direction while coping with tension fluctuations due to thermal expansion and contraction of the metal mesh belt, and does not apply an excessive load to the metal mesh belt.

Means for Solving the Problems

[0012] The tension applying device for a metal mesh belt of the present invention is provided in a belt conveyor having a frame, a driving roller and a driven roller provided on the frame, and a metal mesh belt wound around the driving roller and the driven roller. The tension applying device for a metal mesh belt is provided with a pair of moving mechanisms for holding the driven roller so as to be able to approach and separate from the driving roller whose position is fixed to the frame, and a pair of biasing force generating mechanisms for biasing the driven roller in a direction away from the driving roller. The moving mechanism is composed of bearings provided at both ends of the driven roller, and an upper slide member and a lower slide member fixed to the frame for holding the bearings. The biasing force generating mechanism is composed of an air spring, a fixing member for fixing the air spring to the frame, and a connecting member for connecting the air spring and the bearing. By making the pressure of the compressed air stored inside the air springs of the pair of biasing force generating mechanisms the same, the tension applied to the metal mesh belt is equalized in the width direction, which is a feature of the present invention.

Effect of the Invention

[0013] According to the tension applying device for a metal mesh belt of the present invention, the cost can be reduced by adopting a pair of moving mechanisms and a pair of biasing force generating mechanisms. Also, by simply adjusting the pressure of the compressed air stored inside the air springs of the pair of biasing force generating mechanisms to be the same, the tension applied to the metal mesh belt can be accurately and easily equalized in the width direction while coping with the tension fluctuations due to the thermal expansion and contraction of the metal mesh belt, and the meandering and deformation of the mesh structure can be prevented. Furthermore, since an excessive load is not applied to the metal mesh belt, the life of the metal mesh belt is extended.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention relates to a tension applying device for a metal mesh belt provided on a belt conveyor. The belt conveyor may have a metal mesh belt. For example, a belt conveyor used for a food steamer or a cooler can be mentioned, and more specifically, a belt conveyor used for a rice steamer or a cooler can be mentioned. First, with reference to FIGS. 1 and 2, an outline of a belt conveyor provided with a tension applying device for a metal mesh belt of the present invention will be described. FIG. 1 shows a side view of a belt conveyor 1 used for a cooler provided with a tension applying device 10 according to an embodiment of the present invention. In FIG. 1, only the main parts related to the belt conveyor 1 are shown, and the illustration of structures such as the outer case and the drive motor is omitted.

[0016] As shown in FIG. 1, the main part of the belt conveyor 1 is formed by a frame 2, a drive roller 3 and a driven roller 4 provided on the frame 2, and an endless metal mesh belt 5 wound around the drive roller 3 and the driven roller 4.

[0017] The drive roller 3 is a roller whose position is fixed to the frame 2 and is rotatably provided, and is driven by a drive motor (not shown). The driven roller 4 has its central axis parallel to the central axis of the drive roller 3 and is rotatably provided. When the drive roller 3 is driven, the metal mesh belt 5 circulates and moves on the upper and lower sides (arrows A, B). In the belt conveyor 1 used for a cooler, the conveyed material (for example, steamed rice) loaded on the metal mesh belt 5 is cooled by the supplied air while being conveyed downstream (in the direction of arrow A).

[0018] The shapes of the drive roller 3 and the driven roller 4 may be those generally used for a belt conveyor. For the drive roller 3, a roller with a lining process or groove process in which the roller surface is covered with rubber to prevent slippage of the metal mesh belt 5 may be used. The driven roller 4 may be a cylindrical roller or a roller having a shape in which the diameters of both ends are slightly shorter.

[0019] Hereinafter, the structure of the tension applying device 10 according to an embodiment of the present invention will be described with reference to FIGS. 2 to 5. FIG. 2 is a cross-sectional view taken along the line II-II of the belt conveyor 1 shown in FIG. 1. FIG. 3 is a side view of one of the pair of tension applying devices 10 shown in FIG. 2. FIG. 4 is an enlarged side view showing a main part of the tension applying device 10 shown in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line V-V of FIG. 4. In FIGS. 4 and 5, a part of the frame 2 is omitted, and in FIG. 5, the metal mesh belt 5 is omitted. In the following description, the conveying direction of the metal mesh belt 5 will be described as the front-rear direction, the drive roller 3 side as the front (right side in FIG. 1) when viewed from the driven roller 4, and the driven roller 4 side as the rear (left side in FIG. 1) when viewed from the drive roller 3.

[0020] As shown in FIG. 2, the tension applying device 10 of the present embodiment includes a pair of moving mechanisms 20 that hold the driven roller 4 so as to be able to approach and separate from the drive roller 3 whose position is fixed to the frame 2, and a pair of biasing force generating mechanisms 30 that bias the driven roller 4 in a direction away from the drive roller 3. The pair of moving mechanisms 20 and the pair of biasing force generating mechanisms 30 are respectively provided at both ends of the driven roller 4. For the sake of convenience, the configuration of the moving mechanism 20 and the biasing force generating mechanism 30 on the right side of the driven roller 4 in FIG. 2 will be described as a representative.

[0021] As shown in FIG. 3, the moving mechanism 20 is composed of a bearing 21 provided at the end of the driven roller 4, an upper slide member 23 and a lower slide member 24 fixed to the frame 2 that holds the bearing 21. The biasing force generating mechanism 30 is composed of an air spring 31, a fixing member 32 that fixes the air spring 31 to the frame 2, and a connecting member 35 that connects the air spring 31 and the bearing 21.

[0022] As shown in FIGS. 4 and 5, the bearing 21 of the moving mechanism 20 rotatably holds the shaft end of the driven roller 4, and concave grooves are formed as an upper rail receiver 21a and a lower rail receiver 21b at the upper and lower ends of the bearing 21. The upper slide member 23 and the lower slide member 24 are respectively fitted into the concave grooves of the upper rail receiver 21a and the lower rail receiver 21b of the bearing 21, and hold the bearing 21 in a state where it can move in the front-rear direction. The cross-sectional shapes of the upper slide member 23 and the lower slide member 24 and the cross-sectional shapes of the upper rail receiver 21a and the lower rail receiver 21b of the bearing 21 may be angular or arc-shaped as long as the slide member and the rail receiver are in a slidable contact shape and the slide member can be inserted into the rail receiver.

[0023] Also, a take-up type bearing that can move the driven roller 4 smoothly and stably is adopted for the bearing 21 of the present embodiment. The bearing is not limited to the take-up type bearing, and any bearing that can move smoothly and stably in the front-rear direction while being held by the upper slide member and the lower slide member may be used. For example, guide grooves or the like may be provided along the front-rear direction on the lower surface of the upper slide member and the upper surface of the lower slide member, and the upper and lower ends of the bearing may be accommodated in the grooves so that the bearing can move in the front-rear direction.

[0024] Next, as shown in FIGS. 4 and 5, the air spring 31 of the biasing force generating mechanism 30 includes a rubber bellows 311 that stores compressed air inside, and an intermediate ring 312 for suppressing expansion in the outer peripheral direction is provided at the trough portion of the rubber bellows 311. Front end members 313 and rear end members 314 are provided at both ends of the rubber bellows 311 in the expansion and contraction direction. The fixing member 32 is fixed to the frame 2 so that the rear surface is orthogonal to the front-rear direction of the belt conveyor 1, and the front end member 313 of the air spring 31 is attached to this rear surface. That is, the air spring 31 is provided such that the expansion and contraction direction is the front-rear direction and the base point of its expansion and contraction is the rear surface of the fixing member 32. Although the fixing member 32 and the front end member 313 of the present embodiment are fixed by bolting, it is not particularly limited.

[0025] The air spring 31 is connected to the bearing 21 via a connecting member 35. The connecting member 35 is a stepped shaft with a circular cross-section fixed to the rear end member 314 such that its central axis is coaxial with the central axis of the air spring 31. Specifically, the connecting member 35 is formed of an insertion portion 35a inserted into the insertion hole 21c of the bearing 21, a contact portion 35b that contacts the bearing 21, and a base end portion 35c fixed to the air spring 31. The shaft diameter of the insertion portion 35a is formed to be substantially the same as the inner diameter of the insertion hole 21c, making it difficult to shift in the radial direction during connection. Also, the shaft diameter of the contact portion 35b is larger than the shaft diameter of the insertion portion 35a, and the rear surface of the contact portion 35b contacts the front end surface of the bearing 21 during connection. And the shaft diameter of the base end portion 35c is larger than the shaft diameter of the contact portion 35b and is bolted to the rear end member 314 of the air spring 31. Therefore, the bearing 21 can be stably moved along the expansion and contraction direction of the air spring 31. The connection method between the bearing 21 and the connecting member 35 is not particularly limited as long as the insertion portion 35a of the connecting member 35 can be inserted into and removed from the insertion hole 21c.

[0026] By providing a pair of moving mechanisms 20 and a pair of biasing force generating mechanisms 30 having the above-described configuration, by simply adjusting the pressure of the compressed air stored inside the air springs 31 of the pair of biasing force generating mechanisms 30 to be the same, while corresponding to the tension fluctuations due to thermal expansion and contraction of the metal mesh belt 5, the tension applied to the metal mesh belt 5 can be accurately and easily equalized in the width direction, and snaking and deformation of the mesh structure can be prevented. Furthermore, since an excessive load is not applied to the metal mesh belt 5, the life of the metal mesh belt 5 is extended.

[0027] The air spring 31 described above is defined as having an effective diameter at which pressure effectively acts when the rubber bellows 311 is held at the standard height and a certain amount of compressed air is stored. The effective diameter of the air spring 31 of the biasing force generating mechanism 30 is preferably 100 to 350 mm, and more preferably 120 to 330 mm. Also, the amount of movement of the bearing 21 in the front-rear direction by the moving mechanism 20 is preferably 1 to 50 mm, and more preferably 1 to 30 mm. With this effective diameter and amount of movement, even if the air spring 31 expands and contracts appropriately, or if there are tension fluctuations due to thermal expansion and contraction of the metal mesh belt 5 or a misalignment in the position between the air spring 31 and the bearing 21, an appropriate tension can be applied to the metal mesh belt 5 while stably moving the driven roller 4.

[0028] The limit on the amount of movement of the bearing 21 in the front-rear direction by the moving mechanism 20 may be limited by using an air spring 31 whose maximum elongation stroke amount is within the above range. Also, as shown in FIGS. 3 and 4, a stopper 40 that abuts on the bearing 21 may be provided on the frame 2 to limit the movement of the bearing 21 backward. In the case of this configuration, by adjusting the protruding amount of the stopper 40 protruding toward the bearing 21 side, the maximum amount of movement of the bearing 21 can be easily adjusted.

[0029] Although one embodiment of the present invention has been described, the present invention is not limited thereto, and may be appropriately modified in design. For example, the air spring 31 may be provided with a flat membrane-shaped diaphragm without corrugations instead of the rubber bellows 311. As long as the member for storing compressed air has a structure that can expand and contract along the axial direction and is less likely to bend when expanding and contracting in the axial direction, it can be adopted as an air spring. Further, when the air spring 31 has the rubber bellows 311, the number of peaks of the rubber bellows 311 and the number of intermediate rings 312 provided in the valleys are not particularly limited, and the intermediate rings 312 do not necessarily have to be provided.

Example

[0030] Hereinafter, while explaining an example of the present invention, this embodiment will be described more specifically. In this example, the belt conveyor 1 of the cooler shown in FIGS. 1 to 5 was used, and the effectiveness of the tension applying device 10 of the metal mesh belt 5 of the present invention was confirmed by cooling the steamed rice immediately after steaming.

[0031] The specifications of the belt conveyor 1 are as follows. Metal mesh belt 5 (stainless steel wire): Net width 1800 mm Drive roller 3 and driven roller 4: Width 1850 mm, diameter 400 mm Distance L between the axial centers of the drive roller 3 and the driven roller 4: 8000 mm

[0032] The specifications of the air spring 31 of the tension applying device 10 of the metal mesh belt 5 are as follows. Effective diameter: 220 mm Number of peaks of the rubber bellows 311: 2 Movement amount (expansion and contraction amount) of the bearing 21: 15 mm Pressure of compressed air stored in the air spring 31: 0.15 MPa

[0033] In addition, when the temperature of the metal mesh belt 5 was measured, it was 25°C before operation, and the temperatures on the inlet side and the outlet side during operation were 90°C and 32°C, respectively. Also, it was 27°C one hour after the operation ended.

[0034] As a result of the operation, no deflection or loosening (tension reduction) occurred due to the thermal expansion and contraction of the metal mesh belt 5 caused by the temperature change during operation, and no slip occurred due to a decrease in the frictional force between the metal mesh belt 5 and the drive roller 3. Also, since the biasing forces applied to both ends of the driven roller 4 were maintained in the same state, no meandering of the metal mesh belt 5 occurred. Furthermore, after the operation, the compressed air stored in the air spring 31 was released to remove the tension applied to the metal mesh belt 5, and when the state of the metal mesh belt 5 was checked, there was no deformation of the mesh structure compared to before the operation. As described above, no problems such as poor conveyance of steamed rice occurred during the operation of the cooler. From this, it is presumed that the tension applying device 10 for the metal mesh belt 5 of the present invention was able to equalize the tension applied to the metal mesh belt 5 in the width direction constantly during operation.

[0035] Therefore, by adopting the tension applying device 10 for the metal mesh belt 5 of the present invention, it is possible to accurately and easily equalize the tension applied to the metal mesh belt 5 in the width direction while coping with the tension fluctuations due to the thermal expansion and contraction of the metal mesh belt 5, and to prevent meandering and deformation of the mesh structure. Furthermore, since an excessive load is not applied to the metal mesh belt 5, the life of the metal mesh belt 5 is extended.

Explanation of Signs

[0036] 1 Belt conveyor 2 Frame 3 Drive roller 4 Driven roller 5 Metal mesh belt 10 Tension applying device 20 Moving mechanism 21 Bearing 21a Upper rail receiver 21b Lower rail receiver 21c Insertion hole 23 Upper slide member 24 Lower slide member 30 Biasing force generating mechanism 31 Air spring 311 Rubber Bellows 312 Intermediate Ring 313 Front End Member 314 Rear End Member 32 Fixed Member 35 Connecting Member 35a Insertion Portion 35b Contact Portion 35c Base End Portion 40 Stopper Arrow A Arrow B Distance L

Claims

【Claim 1】 a frame, a driving roller and a driven roller provided on the frame, and a metal mesh belt wound around the driving roller and the driven roller, provided on a belt conveyor, a tension applying device for a metal mesh belt, wherein the tension applying device for the metal mesh belt, comprises a pair of moving mechanisms that hold the driven roller so as to be able to approach and separate from the driving roller whose position is fixed to the frame, and a pair of biasing force generating mechanisms that bias the driven roller in a direction away from the driving roller, and, the moving mechanism, comprises bearings provided at both ends of the driven roller, and an upper slide member and a lower slide member fixed to the frame that hold the bearings, the biasing force generating mechanism, comprises a pneumatic spring having an effective diameter of 100 to 350 mm and including a rubber bellows that stores compressed air inside, a fixing member that fixes the pneumatic spring to the frame, and a connecting member that connects the pneumatic spring and the bearing, a tension applying device for a metal mesh belt, characterized in that the tension applied to the metal mesh belt is equalized in the width direction only by making the pressure of the compressed air stored inside the pneumatic springs of the pair of biasing force generating mechanisms the same.

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