Reciprocating pull-back type tensioning mechanism for coiled material

Abstract

The utility model provides a reciprocating pull-back type tensioning mechanism for coiled materials, which comprises two belts and a driving component for driving the two belts to synchronously drive, and a tensioning mechanism for tensioning the coiled materials is further arranged between the two belts. The tensioning mechanism comprises two sliding rods, two fixing pieces, a first tensioning roller and a second tensioning roller, the two fixing pieces are fixed to the middles of the two sliding rods respectively, the two sliding rods are fixedly connected with the surface of the driving assembly respectively, and the two ends of the first tensioning roller and the two ends of the second tensioning roller slide at the two ends of the two sliding rods respectively. The surfaces of the two sliding rods are sleeved with springs used for resetting the first tensioning roller and the second tensioning roller. According to the reciprocating pull-back type tensioning mechanism for the coiled material, adjustment of the tensioning degree of the coiled material is achieved, the tensioning rollers can rapidly and accurately return to the initial position after reciprocating motion, stable tensioning force is kept, and the service life of the coiled material is prolonged. And deformation or damage of the coiled material caused by too large or too small tensile force is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to coiled material construction technology field especially relates to coiled material reciprocating back tension mechanism. BACKGROUND

[0002] The coiled material tension mechanism is a device for adjusting and controlling the tension of the coiled material, which is widely used in various mechanical equipment related to coiled material processing and handling. During the transmission and processing of the coiled material, maintaining appropriate tension is crucial to ensure processing quality, improve production efficiency and prevent coiled material damage.

[0003] The existing tension mechanism includes a motor, a transmission component and a tension roller, mainly relying on the fixed frequency output of the motor to work. The frequency of the motor is fixed, which causes the tension mechanism to tighten to the preset output frequency of the motor when tightening the coiled material. The motor transmits power to the tension roller through transmission components such as pulleys and chains, causing the tension roller to rotate. During the transmission of the coiled material, the tension roller moves the coiled material through friction with the surface of the coiled material. The size of the tension force mainly depends on the output torque of the motor and the contact pressure between the tension roller and the coiled material. When the tension requirement of the coiled material changes, the tension roller cannot make corresponding adjustments, resulting in unstable tension. For example, when the coiled material becomes thicker, more tension is needed to ensure smooth transmission, but the existing tension mechanism cannot automatically increase the tension. Conversely, when the coiled material becomes thinner, excessive tension will cause the coiled material to be stretched too much, resulting in unstable tension. Unstable tension can cause the coiled material to wrinkle, stretch or compress during transmission, and even tear the coiled material, increasing the risk of coiled material damage. For example, paper coiled material is usually thin and soft, and unstable tension can easily cause the coiled material to wrinkle during transmission. Wrinkles not only affect the appearance quality of the coiled material, but also reduce its strength and increase the risk of tearing, making it inconvenient for actual use.

[0004] Therefore, it is necessary to provide a new reciprocating back tension mechanism for coiled material to solve the above technical problems. INVENTION CONTENTS

[0005] To solve the above technical problems, the utility model provides a reciprocating back tension mechanism for coiled material.

[0006] The reciprocating back tension mechanism for coiled material provided by the utility model comprises two belts and a driving assembly for driving the two belts to synchronously transmit, and a tension mechanism for coiled material tension between the two belts.

[0007] The tensioning mechanism comprises two sliding rods, two fixing members, a tensioning roller one and a tensioning roller two, the two fixing members are fixed at the middle portions of the two sliding rods respectively, the two sliding rods are fixedly connected with the surfaces of the driving assembly respectively, and the two ends of the tensioning roller one and the tensioning roller two slide at the two ends of the two sliding rods respectively, and the surfaces of the two sliding rods are sleeved with springs for resetting the tensioning roller one and the tensioning roller two.

[0008] Preferably, the driving assembly comprises a motor, two rotating shafts, two first belt pulleys and two second belt pulleys, the two first belt pulleys and the two second belt pulleys are driven by two belts respectively, one rotating shaft is fixedly connected with the rotor of the motor, the two first belt pulleys are fixedly connected with the surfaces of the two rotating shafts respectively, a roller is further arranged between the two first belt pulleys and is fixedly connected with the surface of one rotating shaft, and the other rotating shaft is fixedly connected with the surfaces of the two second belt pulleys respectively.

[0009] Preferably, the two ends of the sliding rod are fixedly connected with the surfaces of the first belt pulley and the second belt pulley respectively.

[0010] Preferably, the two fixing members each comprise a mounting plate and a fixing ring, the mounting plate is located outside the belt, the two ends of the mounting plate are fixedly connected with the surfaces of the sliding rod respectively, and the fixing ring is fixed at the middle portion of the mounting plate.

[0011] Preferably, the two ends of the tensioning roller one and the tensioning roller two are fixed with a sliding block one and a sliding block two respectively, the tensioning roller one slides on the surfaces of the two sliding rods through the sliding block one, and the tensioning roller two slides on the surfaces of the two sliding rods through the sliding block two.

[0012] Preferably, the number of the springs is four, the four springs are sleeved on the surfaces of the two sliding rods respectively, two ends of two springs are fixedly connected with one side of the two fixing rings and one side of the two sliding blocks one respectively, and the two ends of the other two springs are fixedly connected with the other side of the two fixing rings and one side of the two sliding blocks two respectively.

[0013] Preferably, the sliding block one and the sliding block two are fixed with the belt through screws, and the sliding block one and the sliding block two are arranged on the two sides of the cross-sectional center line of the belt respectively.

[0014] Compared with the related art, the tensioning mechanism for coiled material has the following beneficial effects:

[0015] The utility model discloses a tensioning mechanism passes through the introduction reciprocating back and draw type movement and spring reset mechanism, can realize the adjustment of the tension of the coiled material, and the spring will be positioned to the moving position of tensioning roller no. In the motor positive and reverse rotation in drive assembly, will drive the transmission of the belt, and the belt will drive tensioning roller no. And tensioning roller no. 2 carry out the similar and the apart movement, and then realize the tension of the coiled material, because the spring is sleeved on the surface of the sliding rod and is used to adjust tensioning roller no. And tensioning roller no. 2 reset, namely for adjusting the similar or the distance of tensioning roller no. And tensioning roller no. 2, when tensioning roller no. And tensioning roller no. 2 are close to each other, the spring is compressed to occur elastic deformation, and the motor speed in drive assembly is slowly reduced, when tensioning roller is close to each other and makes the spring compression, if the motor speed still keeps fast, will lead to tensioning roller to continue fast close, and then make the coiled material be over-tensioned, and the slow reduction of motor speed can make the close speed of tensioning roller gradually reduce, give a buffer time to the system, make the operator have enough time to observe and judge the tension state of the coiled material, avoid the problems, such as stretching, deformation or even tearing, of the coiled material due to over-tensioning, thereby realize the adjustment of the tension of the coiled material, make tensioning roller can quickly, accurately return to the initial position after reciprocating motion, keep the stable tensioning force, avoid the deformation or damage of the coiled material due to the tensioning force being too large or too small. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The utility model provides a reciprocating back and draw type tensioning mechanism for coiled material whole structure schematic diagram of structure is provided;

[0017] Figure 2 The utility model provides a reciprocating back and draw type tensioning mechanism for coiled material whole structure schematic diagram of structure is provided;

[0018] Figure 3 The utility model provides a reciprocated back and draw type tensioning mechanism for coiled material part of structure schematic diagram of structure is provided Figure 1 ;

[0019] Figure 4 The utility model provides a reciprocated back and draw type tensioning mechanism for coiled material part of structure schematic diagram of structure is provided Figure 2 ;

[0020] Figure 5 The utility model provides a reciprocated back and draw type tensioning mechanism for coiled material part of structure schematic diagram of structure is provided Figure 3 .

[0021] The figure mark: 1, motor; 11, rotating shaft; 12, roller; 2, first pulley; 21, second pulley; 22, slide rod; 221, fixed ring; 222, spring; 3, mounting plate; 4, belt; 5, slide block one; 51, tensioning roller one; 6, slide block two; 61, tensioning roller two. DETAILED DESCRIPTION

[0022] The utility model will be further explained below in combination with the drawings and embodiments.

[0023] Please see Figures 1 to 5 , wherein, Figure 1 It is the overall structure schematic view of reciprocating back tension mechanism for coiled material provided by the utility model; Figure 2 It is the overall structure schematic view of reciprocating back tension mechanism for coiled material provided by the utility model; Figure 3 It is the sectional structure schematic view of reciprocating back tension mechanism for coiled material provided by the utility model Figure 1 ; Figure 4 It is the sectional structure schematic view of reciprocating back tension mechanism for coiled material provided by the utility model Figure 2 ; Figure 5 It is the sectional structure schematic view of reciprocating back tension mechanism for coiled material provided by the utility model Figure 3 .

[0024] Some embodiments, as shown in Figures 1 to 5 , including two belts 4 and the drive assembly for driving two belts 4 synchronous transmission, characterized in that, two belts 4 between still be equipped with the tensioning mechanism for coiled material tensioning;

[0025] The tensioning mechanism includes two slide rods 22, two fixed parts, tensioning roller one 51 and tensioning roller two 61, two fixed parts are fixed in the middle of two slide rods 22, two slide rods 22 are respectively connected with the surface fixed part of drive assembly, and the both ends of tensioning roller one 51 and tensioning roller two 61 are respectively in the both ends of two slide rods 22 sliding, and the surface of two slide rods 22 is all sheathed with the spring 222 for the reset of tensioning roller one 51 and tensioning roller two 61;

[0026] The drive assembly includes motor 1, two rotating shafts 11, two first pulleys 2 and two second pulleys 21, two first pulleys 2 and two second pulleys 21 are driven through two belts 4 respectively, one of rotating shafts 11 is fixedly connected with the rotor of motor 1, two first pulleys 2 are respectively fixedly connected with the surface of one of rotating shafts 11, and the roller 12 is further provided between two first pulleys 2, and the roller 12 is fixedly connected with the surface of one of rotating shafts 11, and the other rotating shaft 11 is respectively fixedly connected with the surface of two second pulleys 21;

[0027] The two ends of the slide bar 22 are respectively fixedly connected with the surfaces of the first belt pulley 2 and the second belt pulley 21.

[0028] The sizes of the two first belt pulleys 2 and the two second belt pulleys 21 are matched, and the two first belt pulleys 2 and the two second belt pulleys 21 can synchronously rotate coaxially when the motor 1 is driven.

[0029] When the motor 1 in the driving group is started, one of the two rotating shafts 11 is driven to rotate. Since the roller 12 is fixedly connected with the surface of one of the two rotating shafts 11, the other rotating shaft 11 is respectively fixedly connected with the surfaces of the two second belt pulleys 21. Under the driving of the motor 1, the two rotating shafts 11 are driven to synchronously rotate coaxially. The two ends of the two rotating shafts 11 are respectively fixedly connected with the two first belt pulleys 2 and the two second belt pulleys 21. The two second belt pulleys 21 are respectively fixedly connected with the two ends of the roller 12. The two first belt pulleys 2 and the two second belt pulleys 21 are engaged and driven by the belt 4. Under the rotation of the first belt pulley 2, the two second belt pulleys 14 are driven to rotate, the two belts 4 are synchronously driven, and the roller 12 is driven to rotate. The surface of the roller 12 is sleeved with a coiled material cylinder. The rotation of the roller 12 does not affect the release of the coiled material from the coiled material cylinder.

[0030] Specifically, by introducing the reciprocating back-pulling movement mode and the spring 222 reset mechanism, the adjustment of the coiled material tension can be realized. During the coiled material transmission and processing, the spring 222 limits the moving positions of the tension roller one 51 and the tension roller two 61. The tension roller one 51 and the tension roller two 61 are respectively arranged on the two sides of the cross-sectional center line of the belt 4. When the motor 1 in the driving assembly is reversed, the belt 4 is driven to transmit, and the belt 4 drives the tension roller one 51 and the tension roller two 61 to move close to each other and move away from each other, thereby realizing the tensioning of the coiled material. Since the spring 222 is sleeved on the surface of the slide rod 22 and is used to adjust the reset of the tension roller one 51 and the tension roller two 61, that is, to adjust the distance between the tension roller one 51 and the tension roller two 61 when they move close to each other. When the tension roller one 51 and the tension roller two 61 move close to each other, the spring is elastically deformed and compressed, and the speed of the motor 1 in the driving assembly is slowly reduced. When the tension roller one 51 and the tension roller two 61 move close to each other and compress the spring 222, if the speed of the motor 1 remains fast, it will cause the tension roller one 51 and the tension roller two 61 to continue to move close to each other quickly, thereby over-tensioning the coiled material. Slowly reducing the speed of the motor 1 can gradually reduce the speed of the tension roller one 51 and the tension roller two 61 moving close to each other, giving the system a buffer time, allowing the operator enough time to observe and judge the tensioning state of the coiled material, avoiding the problem of stretching, deformation or even tearing of the coiled material due to over-tensioning, thereby realizing the adjustment of the tension of the coiled material, and enabling the tension roller one 51 and the tension roller two 61 to quickly and accurately return to the initial position after reciprocating movement, maintaining a stable tensioning force, and avoiding the deformation or damage of the coiled material caused by excessive or insufficient tensioning force.

[0031] Further, two paper coiled materials with different thicknesses are selected as test objects, the thicknesses are 0.1 mm and 0.2 mm respectively, and the output frequency of the motor 1 is set to a fixed value of 50 Hz.

[0032] The tensioning mechanism is installed on the support, and the driving assembly and the motor 1 are connected. The initial positions of the sliding block one 5 and the sliding block two 6 are adjusted to ensure that the distance between the tension roller one 51 and the tension roller two 61 is moderate. The motor 1 is started, and the operation of the tensioning mechanism is observed to ensure that the belt 4 can normally transmit, and the sliding block one 5 and the sliding block two 6 can smoothly slide on the slide rod 22. At this time, the paper coiled materials with thicknesses of 0.1 mm and 0.2 mm are used for testing. The paper coiled material with a thickness of 0.1 mm is installed on the coiled material transmission mechanism, the motor 1 is started, and the motor 1 is operated in forward and reverse rotation to simulate reciprocating back-pulling movement. The distance change between the tension roller one 51 and the tension roller two 61 and the transmission state of the coiled material are observed and recorded.

[0033] Recorded data: After the motor 1 is stably operated, the distance between the tension roller one 51 and the tension roller two 61 fluctuates between 95 mm and 105 mm, and the coiled material is transmitted stably without wrinkles or stretching.

[0034] At this time, replace the paper web with a thickness of 0.2 mm, repeat the above test steps, and observe and record the distance change between the tensioning roller one 51 and the tensioning roller two 61 and the transmission state of the web;

[0035] Recorded data: After the motor 1 runs stably, the distance between the tensioning roller one 51 and the tensioning roller two 61 fluctuates between 98 mm and 108 mm. Due to the increase in the thickness of the web, the distance between the tensioning roller one 51 and the tensioning roller two 61 increases accordingly, and the web is transmitted stably without wrinkles or stretching.

[0036] Analysis: When the output frequency of the motor 1 is fixed at 50 Hz, the tensioning mechanism can flexibly adjust the distance between the tensioning roller one 51 and the tensioning roller two 61 through the reciprocating pulling type movement and the spring 222 reset mechanism to meet the tensioning needs of different webs.

[0037] For paper webs with thicknesses of 0.1 mm and 0.2 mm, the tensioning mechanism can adjust the tensioning force to an appropriate range to ensure that the web remains flat and wrinkle-free during transmission. During the reciprocating pulling type movement, the slider one 5 and the slider two 6 can smoothly slide on the slide rod 22, and the moving distance meets the design requirements. The spring 222 can limit and reset the slider one 5 and the slider two 6 to ensure that the tensioning roller one 51 and the tensioning roller two 61 can quickly and accurately return to the vicinity of the initial position after reciprocating, maintaining a stable tensioning force, that is:

[0038] The motor 1 drives the belt 4 through the rotating shaft 11 and the first pulley 2. In the process of transmission, the belt 4 drives the slider 1 and the slider 2 to move close to or away from each other on the slide rod 22. When the motor 1 rotates forward, the belt 4 drives the slider 1 and the slider 2 to move away from each other, thereby increasing the distance between the tensioning roller 1 and the tensioning roller 2, and realizing the tensioning of the coiled material. When the motor 1 reverses, the belt 4 drives the slider 1 and the slider 2 to move close to each other, thereby reducing the distance between the tensioning roller 1 and the tensioning roller 2. When the motor 1 reverses or stops, the transmission direction of the belt 4 changes, resulting in a decrease in the force acting on the slider 1 and the slider 2. Specifically, when the motor 1 reverses, the belt 4 tries to drive the slider 1 and the slider 2 to move in the opposite direction, but due to the limiting effect of the spring 222, the slider 1 and the slider 2 do not immediately move in the opposite direction, but are subjected to the restoring force of the spring 222. In the process of the motor 1 driving the belt 4, the spring 222 is subjected to the extrusion or stretching of the slider 1 and the slider 2, thereby deforming and storing elastic potential energy. When the motor 1 reverses or stops, the force of the belt 4 on the slider 1 and the slider 2 decreases, and the spring 222 begins to release the stored elastic potential energy. In the process of the spring 222 releasing the elastic potential energy, a restoring force opposite to the deformation direction is generated, pushing the slider 1 and the slider 2 to move towards the initial position. Under the action of the restoring force of the spring 222, the slider 1 and the slider 2 quickly and accurately return to the initial position or approach the initial position, thereby maintaining the stability and reliability of the tensioning mechanism.

[0039] Reason for avoiding damage: When the motor 1 drives the belt 4, the slider 1 and the slider 2 move on the slide rod 22 under the action of the belt 4, and at the same time, the spring 222 is extruded or stretched, storing elastic potential energy.

[0040] When the motor 1 reverses or stops, the force of the belt 4 on the slider 1 and the slider 2 decreases, and the spring 222 begins to release the stored elastic potential energy, generating a restoring force to push the slider 1 and the slider 2 to move towards the initial position.

[0041] This storage and release process of elastic potential energy allows the distance between the tensioning roller 1 and the tensioning roller 2 to be flexibly adjusted according to the rotation direction of the motor 1, thereby realizing the adjustment of the tensioning force of the coiled material. The restoring force of the spring 222 is always opposite to the moving direction of the slider 1 and the slider 2. When the tensioning force is too large, the spring 222 is further compressed or stretched, storing more elastic potential energy, and releasing it to reduce the tensioning force.

[0042] Conversely, when the tension is too small, the reset force of the spring 222 will push the slider 5 and the slider 6 to move away, increase the distance between the tension roller 51 and the tension roller 61, thereby increasing the tension, so that the coiled material always maintains a stable tension during transmission, avoiding the deformation or damage of the coiled material caused by excessive tension or too small tension. The spring 222 reset mechanism has a simple and reliable structure, can maintain stable reset performance after long time operation, and improves the reliability and service life of the tensioning mechanism.

[0043] In some embodiments, as shown in Figures 1 to 5 Both fixing members include a mounting plate 3 and a fixing ring 221, the mounting plate 3 is located outside the belt 4, both ends of the mounting plate 3 are fixedly connected with the surfaces of the slide rods 22, and the fixing ring 221 is fixed in the middle of the mounting plate 3.

[0044] Both ends of the tension roller 51 and the tension roller 61 are fixed with the slider 5 and the slider 6 respectively, the tension roller 51 slides on the surfaces of the two slide rods 22 through the slider 5, and the tension roller 61 slides on the surfaces of the two slide rods 22 through the slider 6.

[0045] The number of springs 222 is four, the four springs 222 are sleeved on the surfaces of the two slide rods 22, and both ends of two springs 222 are fixedly connected with one side of the two fixing rings 221 and one side of the two sliders 5 respectively, and both ends of the other two springs 222 are fixedly connected with the other side of the two fixing rings 221 and one side of the two sliders 6 respectively.

[0046] When the tension roller 51 and the tension roller 61 move close to each other, the spring 222 is elastically deformed and compressed at this time, the motor 1 in the driving assembly slowly reduces the speed, and when the tension roller 51 and the tension roller 61 move close to each other to compress the spring 222, slowly reducing the speed of the motor 1 can gradually reduce the closing speed of the tension roller 51 and the tension roller 61, giving the system a buffer time, allowing the operator to have enough time to observe and judge the tensioning state of the coiled material, avoiding the problems of stretching, deformation or even tearing of the coiled material due to excessive tensioning.

[0047] Conversely, when the tension roller 51 and the tension roller 61 move away from each other, the spring 222 is elastically deformed and stretched at this time, the motor 1 in the driving assembly slowly reduces the speed, and plays a buffering role.

[0048] The slider 5 and the slider 6 are fixed between the belt 4 by screws, and the slider 5 and the slider 6 are respectively arranged on both sides of the middle line of the cross section of the belt 4.

[0049] Specifically, by introducing the reciprocating back-pulling type movement and the spring 222 reset mechanism, the adjustment of the coiled material tension can be realized. During the coiled material transmission and processing, the spring 222 limits the moving positions of the tension roller one 21 and the tension roller two 61. The slider one 5 and the slider two 6 are respectively arranged on the two sides of the cross-section center line of the belt 4, i.e. on the upper and lower sides of the inner diameter of the belt 4. The surfaces of the slider one 5 and the slider two 6 are fixedly connected with the surface of the belt 4 through screws. When the motor 1 in the driving assembly is reversed, the belt 4 is driven to transmit, and the belt 4 drives the slider one 5 and the slider two 6 to move close to each other and move away from each other, thereby realizing the tensioning of the coiled material. Since the spring 222 is sleeved on the surface of the slide rod 22 and is used for adjusting the distance between the tension roller one 51 and the tension roller two 61, the slider one 5 and the slider two 6 cannot exceed the predetermined range during the movement, so that the tension roller one 51 and the tension roller two 61 can quickly and accurately return to the initial position after reciprocating, keep stable tension, and avoid coiled material deformation or damage caused by excessive or insufficient tension.

[0050] The circuit and the control involved in the utility model are prior art, and will not be described in detail here.

[0051] The above is only an embodiment of the utility model, and does not limit the patent range of the utility model. Any equivalent structure or equivalent process conversion or direct or indirect application in other related technical fields based on the content of the utility model specification and drawings is also included in the patent protection range of the utility model.

Claims

1. A reciprocating pull-back tensioning mechanism for rolled materials, comprising two belts (4) and a drive assembly for synchronously driving the two belts (4), characterized in that, A tensioning mechanism for tensioning the roll is also provided between the two belts (4); The tensioning mechanism includes two slide rods (22), two fixing members, tensioning roller one (51) and tensioning roller two (61). The two fixing members are respectively fixed in the middle of the two slide rods (22). The two slide rods (22) are respectively fixedly connected to the surface of the drive assembly. The two ends of tensioning roller one (51) and tensioning roller two (61) slide at the two ends of the two slide rods (22). The surfaces of the two slide rods (22) are each sleeved with a spring (222) for resetting tensioning roller one (51) and tensioning roller two (61).

2. The reciprocating pull-back tensioning mechanism for roll materials according to claim 1, characterized in that, The drive assembly includes a motor (1), two shafts (11), two first pulleys (2) and two second pulleys (21). The two first pulleys (2) and the two second pulleys (21) are driven by two belts (4). One of the shafts (11) is fixedly connected to the rotor of the motor (1). The two first pulleys (2) are fixedly connected to the surface of one of the shafts (11). A roller (12) is also provided between the two first pulleys (2), and the roller (12) is fixedly connected to the surface of one of the shafts (11). The other shaft (11) is fixedly connected to the surface of the two second pulleys (21).

3. The reciprocating pull-back tensioning mechanism for roll materials according to claim 2, characterized in that, The two ends of the slide bar (22) are fixedly connected to the surfaces of the first pulley (2) and the second pulley (21), respectively.

4. The reciprocating pull-back tensioning mechanism for roll materials according to claim 3, characterized in that, Both of the fasteners include a mounting plate (3) and a fixing ring (221). The mounting plate (3) is located on the outside of the belt (4). Both ends of the mounting plate (3) are fixedly connected to the surface of the slide bar (22), and the fixing ring (221) is fixed in the middle of the mounting plate (3).

5. The reciprocating pull-back tensioning mechanism for roll materials according to claim 4, characterized in that, The tension roller 1 (51) and the tension roller 2 (61) are respectively fixed with slider 1 (5) and slider 2 (6) at both ends. The tension roller 1 (51) slides on the surface of the two slide rods (22) through slider 1 (5), and the tension roller 2 (61) slides on the surface of the two slide rods (22) through slider 2 (6).

6. The reciprocating pull-back tensioning mechanism for roll materials according to claim 5, characterized in that, The number of springs (222) is four. The four springs (222) are respectively sleeved on the surface of the two slide rods (22). The two ends of the two springs (222) are respectively fixedly connected to one side of the two fixed rings (221) and one side of the two sliders (5). The two ends of the other two springs (222) are respectively fixedly connected to the other side of the two fixed rings (221) and one side of the two sliders (6).

7. The reciprocating pull-back tensioning mechanism for roll materials according to claim 6, characterized in that, The slider one (5) and the slider two (6) are fixed to the belt (4) by screws, and the slider one (5) and the slider two (6) are respectively located on both sides of the center line of the cross section of the belt (4).

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