Frictional dancer roller

Abstract

This utility model discloses a friction-type alignment roller in the field of sewing machine alignment roller technology. It includes an alignment roller, a motor, and a convex mounting hole. The convex mounting hole is formed inside the alignment roller, and the output shaft of the motor is inserted into the convex mounting hole. An installation structure is installed between the output shaft of the motor and the convex mounting hole, with at least four installation structures. A groove is formed on the output shaft of the motor, and a retaining plate is rotatably connected to the groove via a pin. A first spring is installed between the retaining plate and the groove, and a retaining slot is formed inside the convex mounting hole. The retaining plate engages in the retaining slot. When the convex mounting hole on the alignment roller is fitted onto the output shaft of the motor, as the front end of the motor output shaft enters the left side position of the convex mounting hole, the elasticity of the first spring causes the retaining plate to rotate outward within the groove via the pin, engaging the retaining plate into the retaining slot. This facilitates the installation of the alignment roller on the motor output shaft and, conversely, facilitates the removal and replacement of a slipping alignment roller.

Description

Technical Field

[0001] This utility model relates to the field of alignment roller technology, specifically a friction alignment roller. Background Technology

[0002] Belt conveyors are widely used in numerous industries such as metallurgy, coal, power, building materials, chemicals, transportation, and light industry ports. Their stable operation is crucial to the entire production process. Among the many components of a belt conveyor, self-aligning friction idlers play an indispensable role. Their main function is to promptly correct belt misalignment during operation, preventing a series of problems caused by belt misalignment, such as material spillage, accelerated belt wear, and even equipment failure.

[0003] Currently, various friction-adjusting idlers exist on the market. For example, the "Self-aligning Friction Idler" with application number "CN201420648378.8" features convenient installation, reliable sealing, and low dust accumulation; the "New Type of Self-aligning Idler" with application number "CN201620477539.0" can directly replace ordinary idlers, can be adjusted manually or electrically, quickly solves conveyor belt misalignment problems, and is low in cost, has a wide angle adjustment range, and is easy to operate. However, a deeper analysis of these existing self-aligning idlers reveals some common shortcomings. First, their installation methods are relatively simple, lacking sufficient flexibility when facing different installation environments and equipment layouts; second, their usage methods are not diverse enough, making it difficult to flexibly combine them according to changes in actual working conditions. This often leads to companies needing to purchase multiple specifications of self-aligning idlers for different scenarios, thus increasing costs. Utility Model Content

[0004] The purpose of this invention is to provide a friction-adjusting idler roller to solve the existing problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a frictional alignment roller, comprising an alignment roller, a motor, and a convex mounting hole, wherein the convex mounting hole is formed inside the alignment roller, the output shaft of the motor is inserted into the convex mounting hole, and an mounting structure is installed between the output shaft of the motor and the convex mounting hole, wherein the number of mounting structures is not less than four, the mounting structures are distributed in a ring at equal intervals, and the mounting structure includes a groove, a retaining plate, a pin, a first spring, and a retaining slot;

[0006] The groove is formed on the output shaft of the motor, the clamping plate is rotatably connected to the groove via a pin, the first spring is installed between the clamping plate and the groove, the slot is formed in the convex mounting hole, and the clamping plate is engaged in the slot.

[0007] As a preferred embodiment of the friction-adjusting idler of this utility model, a rotating arm is provided on the inner side of the adjusting idler, the motor is mounted on the rotating arm, a through hole is provided on the rotating arm, and the output shaft of the motor is placed in the through hole.

[0008] As a preferred embodiment of the friction-adjusting idler roller of this utility model, an mounting plate is provided on the inner side of the rotating arm, a U-shaped groove is provided on the mounting plate, a servo motor is mounted on the mounting plate, the output shaft of the servo motor is placed in the U-shaped groove, and the rotating arm is mounted on the output shaft of the servo motor.

[0009] As a preferred embodiment of the friction-adjusting idler roller of this utility model, a limiting shaft is installed on the mounting plate, a movable plate is provided outside the limiting shaft, a movable groove is opened on the movable plate, the limiting shaft is placed in the movable groove, and a rotating shaft is installed on the rotating arm.

[0010] As a preferred embodiment of the friction-adjusting idler roller of this utility model, a vertical rod is installed on the movable plate, a sleeve is fitted over the vertical rod, a spring mechanism is installed in the internal space between the vertical rod and the sleeve, a connecting piece is installed on the sleeve, and the connecting piece is rotatably connected to the rotating arm via a rotating shaft.

[0011] As a preferred embodiment of the friction-adjusting idler roller of this utility model, the mounting plate is equipped with an ear plate.

[0012] As a preferred embodiment of the friction-adjusting roller of this utility model, bolt holes are provided on the ear plate.

[0013] As a preferred embodiment of the friction-adjusting idler roller of this utility model, the spring mechanism includes a fixed plate, a telescopic rod vertically mounted on the upper end of the fixed plate, a universal seat mounted on the top end of the telescopic rod, a universal ball installed inside the universal seat, a second spring fitted on the outside of the telescopic rod, and rotating cavities evenly spaced along the axis of the inner wall of the universal seat, with ball bearings installed inside the rotating cavities.

[0014] Compared with the prior art, the beneficial effects of this utility model are: the setting of the sewing machine's deviation adjustment roller has a reasonable structural design;

[0015] The friction-adjusting idler in this patent features a unique mounting structure between the motor output shaft and the convex mounting hole. The clamping plate in the mounting structure is rotatably connected to a groove via a pin, and, with the help of the elastic force of a first spring, can be tightly engaged in the slot within the convex mounting hole. This design makes the connection between the motor output shaft and the adjusting idler extremely stable. Furthermore, during installation or disassembly, simply overcoming the elastic force of the first spring by rotating the clamping plate allows for separation or connection, making the operation very simple and greatly improving the efficiency of equipment maintenance and assembly.

[0016] The rotating arm located inside the adjusting idler provides the crucial motion foundation for the entire device's alignment function. A motor is mounted on the rotating arm and driven by a servo motor. When the conveyor belt deviates from its designated path, the servo motor precisely controls the rotation angle of the rotating arm, thereby adjusting the angle of the adjusting idler accordingly. The U-shaped groove on the mounting plate facilitates the installation of the servo motor's output shaft and ensures the stability of the rotating arm during rotation. Furthermore, the cooperation between the limiting shaft on the mounting plate and the movable groove on the movable plate, along with the connection of the movable plate to the rotating arm via a vertical rod, sleeve, and spring mechanism, effectively limits and buffers the rotation of the arm, preventing damage caused by excessive rotation or external impact, further improving the accuracy of alignment and the reliability of the equipment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a schematic diagram of the limiting shaft, movable plate, and movable groove of this utility model;

[0019] Figure 3 This is a schematic diagram of the vertical rod, sleeve, and spring mechanism of this utility model;

[0020] Figure 4 This is a schematic diagram of the groove, clamping plate, and pin structure of this utility model.

[0021] In the diagram: 1. Adjusting roller, 2. Motor, 3. Convex mounting hole, 4. Mounting structure, 401. Groove, 402. Clamping plate, 403. Pin, 404. First spring, 405. Slot, 5. Mounting plate, 6. U-shaped groove, 7. Servo motor, 8. Rotating arm, 9. Ear plate, 10. Bolt hole, 11. Limiting shaft, 12. Movable plate, 13. Movable groove, 14. Vertical rod, 15. Sleeve, 16. Spring mechanism, 161. Fixed plate, 162. Telescopic rod, 163. Universal seat, 164. Universal ball, 165. Spring, 166. Rotating cavity, 167. Ball bearing, 17. Connector, 18. Rotating shaft. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Please see Figure 1-4This utility model provides a technical solution:

[0024] In this technical solution, a friction-adjusting idler roller includes an adjusting idler roller 1, a motor 2, and a convex mounting hole 3. The convex mounting hole 3 is formed inside the adjusting idler roller 1. The output shaft of the motor 2 is inserted into the convex mounting hole 3. An installation structure 4 is installed between the output shaft of the motor 2 and the convex mounting hole 3. The number of installation structures 4 is not less than four, and the installation structures 4 are distributed in a ring at equal intervals. The installation structure 4 includes a groove 401, a clamping plate 402, a pin 403, a first spring 404, and a slot 405. The groove 401 is formed on the output shaft of the motor 2. The clamping plate 402 is rotatably connected to the groove 401 through the pin 403. The first spring 404 is installed between the clamping plate 402 and the groove 401. The slot 405 is formed inside the convex mounting hole 3, and the clamping plate 402 is engaged in the slot 405.

[0025] To ensure stability and reliability during long-term use, the output shaft of motor 2, where groove 401 is located, is made of high-strength alloy steel with a yield strength of not less than 600MPa and a tensile strength between 800-1000MPa. This allows it to withstand significant torque and external impacts, ensuring it will not deform or break under complex working conditions. The clamping plate 402 is made of high-quality stainless steel, such as 304 stainless steel, which has good corrosion resistance and mechanical strength, allowing it to function normally in harsh environments such as humid and dusty conditions. Its hardness reaches HV200-250, sufficient to handle frequent clamping and disengaging actions. The pin 403 is made of 45# medium carbon steel and has undergone quenching and tempering, achieving a surface hardness of HRC40-45. The core maintains a certain degree of toughness, ensuring it is not easily worn or broken during frequent rotation, while also ensuring the flexible rotation of the clamping plate 402. The first spring 404 is made of spring steel, such as 65Mn spring steel. This material has a high elastic limit and fatigue strength. After appropriate heat treatment, its elastic modulus is between 190-210GPa, which can provide stable and durable elastic force for the card plate 402, ensuring that the card plate 402 is always tightly engaged in the card slot 405.

[0026] The groove 401 is designed with a depth of 8-10mm and a width of 12-15mm. These dimensions ensure sufficient rotation space for the clamping plate 402 within the groove, while also guaranteeing the precision of the fit between the clamping plate 402 and the groove wall during engagement, preventing wobbling. The clamping plate 402 is 20-25mm long, 10-12mm wide, and 3-5mm thick. Its length must ensure it can penetrate a certain depth into the clamping groove 405 during engagement, providing sufficient clamping force. The width and thickness are optimized based on the selected material and the external forces it will withstand to ensure the strength of the clamping plate 402. The pin 403 has a diameter of 6-8mm and a length slightly greater than the width of the groove 401 to ensure that the ends of the pin do not dislodge from the groove when the clamping plate 402 rotates. The depth of the slot 405 in the convex mounting hole 3 is 10-12mm, and the width is adapted to the width of the card plate 402. The tolerance is controlled within ±0.2mm to ensure that the card plate 402 can be accurately inserted and the gap after the card is engaged is extremely small to avoid loosening.

[0027] During installation, the clamping plate 402 is first installed in the groove 401 via the pin 403, ensuring that the clamping plate 402 rotates freely without jamming. Then, the first spring 404 is installed between the clamping plate 402 and the groove 401. During installation, attention should be paid to the pre-compression of the spring, generally controlled at 2-3mm. Pre-compression generates initial elasticity in the spring, ensuring that the clamping plate 402 maintains an outward opening tendency in its natural state. When the output shaft of the motor 2 is inserted into the convex mounting hole 3, the clamping plate 402 automatically engages with the slot 405 under the action of the first spring 404, completing the installation. To further ensure the stability of the installation, after installation, the engagement point between the clamping plate 402 and the slot 405 can be reinforced by spot welding. However, the spot welding strength must be controlled within a certain range so that when disassembly is required, the weld point can be broken with a small external force to achieve separation of the components.

[0028] The rotating arm 8 is made of aluminum alloy, such as 6061 aluminum alloy. This material has the characteristics of low density and high strength, with a density of approximately 2.7 g / cm³ and a tensile strength of over 200 MPa. While ensuring the mechanical strength of the rotating arm 8, it reduces the overall weight, which helps to reduce drive energy consumption. The length of the rotating arm 8 is determined according to the actual application scenario and the installation position of the alignment roller 1, generally between 300-500 mm, the width is 80-120 mm, and the thickness is 15-20 mm. Its shape is designed with a mounting base for mounting the motor 2 at one end, and the other end is connected to other components through a rotating shaft. The mounting base needs to be precision machined to ensure that the coaxiality error of the motor 2 is controlled within ±0.1 mm after installation, and to ensure the parallelism between the output shaft of the motor 2 and the axis of the alignment roller 1.

[0029] The rotating arm 8 is mounted on the output shaft of the servo motor 7 and reliably connected via a keyed connection and a nut. A keyway is machined at the mating point between the rotating arm 8 and the output shaft of the servo motor 7. The keyway's dimensional accuracy conforms to national standards and fits tightly with the selected flat key, with a key tolerance controlled within ±0.05mm. After installing the key, the rotating arm 8 is fitted onto the output shaft of the servo motor 7 and then tightened with a high-strength nut. The tightening torque of the nut is determined based on the size and material of the rotating arm 8, generally between 80-120 N·m, ensuring that the rotating arm 8 does not experience relative displacement with the output shaft of the servo motor 7 during rotation.

[0030] In some technical solutions, a mounting plate 5 is provided on the inner side of the rotating arm 8. A U-shaped groove 6 is provided on the mounting plate 5. A servo motor 7 is mounted on the mounting plate 5. The output shaft of the servo motor 7 is placed in the U-shaped groove 6. The rotating arm 8 is mounted on the output shaft of the servo motor 7.

[0031] Mounting plate 5 is made of Q235 carbon steel and galvanized to improve its corrosion resistance. The dimensions of mounting plate 5 are determined based on the other components being installed and the overall structural layout; generally, it is 200-300mm long, 150-200mm wide, and 8-10mm thick. A U-shaped groove 6 is formed on mounting plate 5 for mounting the output shaft of servo motor 7. The width of the U-shaped groove 6 is 2-3mm larger than the diameter of the servo motor 7's output shaft, and its depth is 30-40mm, ensuring that the servo motor 7's output shaft can rotate freely within the U-shaped groove 6. Simultaneously, the two side walls of the U-shaped groove 6 need to be polished, with a surface roughness controlled below Ra 3.2μm to reduce friction during rotation.

[0032] The limiting shaft 11 is made of 45# steel and its surface is hardened to HRC45-50 to improve its wear resistance. The diameter of the limiting shaft 11 is 10-12mm, and its length is determined according to the distance between the mounting plate 5 and the movable plate 12, generally extending 50-80mm beyond the surface of the mounting plate 5. The movable plate 12 is made of the same Q235 carbon steel as the mounting plate 5. The movable groove 13 is formed on the movable plate 12. The width of the movable groove 13 is 1-2mm larger than the diameter of the limiting shaft 11, and its length is 50-80mm. The movable plate 12 cooperates with the limiting shaft 11 through the movable groove 13, allowing it to move freely axially on the limiting shaft 11. The fit tolerance between the limiting shaft 11 and the movable groove 13 is controlled within H9 / f9 to ensure that the movable plate 12 moves smoothly without wobbling.

[0033] In some technical solutions, a limiting shaft 11 is installed on the mounting plate 5, and a movable plate 12 is provided outside the limiting shaft 11. A movable groove 13 is formed on the movable plate 12, and the limiting shaft 11 is placed within the movable groove 13. A rotating shaft 18 is installed on the rotating arm 8. A vertical rod 14 is installed on the movable plate 12, and a sleeve 15 is fitted over the vertical rod 14. A spring mechanism 16 is installed in the internal space between the vertical rod 14 and the sleeve 15. A connecting piece 17 is installed on the sleeve 15, and the connecting piece 17 is rotatably connected to the rotating arm 8 via the rotating shaft 18. An ear plate 9 is installed on the mounting plate 5.

[0034] Bolt holes 10 are provided on the ear plate 9.

[0035] The vertical rod 14 is made of stainless steel, such as 316 stainless steel, to ensure corrosion resistance in humid environments. The diameter of the vertical rod 14 is 8-10mm, and its length is determined according to actual installation requirements, generally between 100-150mm. The sleeve 15 is made of aluminum alloy, with an inner diameter 1-2mm larger than the diameter of the vertical rod 14, and an outer diameter determined according to the dimensions of the installed spring mechanism 16, generally between 20-30mm. The fixing plate 161 in the spring mechanism 16 is made of 45# steel, with a thickness of 6-8mm, and its dimensions are determined according to the layout of the installed telescopic rod 162 and the second spring 165. The telescopic rod 162 is made of high-strength alloy steel with an outer diameter of 6-8mm. Its stroke is determined according to actual needs, generally between 20-40mm. A universal joint 163 is installed at the top of the telescopic rod 162, and a universal ball 164 with a diameter of 10-12mm is installed inside the universal joint 163, allowing free rotation within the universal joint 163 for flexible multi-angle connections. The second spring 165 is made of the same 65Mn spring steel as the first spring 404. Its spring constant is determined according to the required buffering force, generally between 10-20N / mm. The free length of the spring is 40-60mm, and the pre-compression during installation is controlled at 10-20mm. This pre-compression generates initial elasticity in the spring, providing buffering and adjustment. Rotating cavities 166 are evenly spaced on the inner wall of the universal joint 163. The diameter of the rotating cavities 166 is 6-8mm, and the diameter of the ball bearings 167 installed inside is 4-6mm. The ball bearings 167 can roll freely in the rotating cavities 166, further reducing friction during rotation and improving the flexibility of the spring mechanism 16 at different angles.

[0036] In some technical solutions, the spring mechanism 16 includes a fixed plate 161, a telescopic rod 162 is vertically mounted on the upper end of the fixed plate 161, a universal seat 163 is mounted on the top end of the telescopic rod 162, a universal ball 164 is installed inside the universal seat 163, a second spring 165 is fitted on the outside of the telescopic rod 162, and rotating cavities 166 are evenly spaced along the axis of the inner wall of the universal seat 163, with ball bearings 167 installed inside the rotating cavities 166.

[0037] Initial Installation Stage: When installing the friction-adjusting idler onto the belt conveyor, firstly, use M12-M16 high-strength bolts to fix the mounting plate 5 to the belt conveyor frame through the bolt holes 10 on the ear plate 9. The tightening torque of the bolts should be controlled between 100-150 N·m to ensure the mounting plate 5 is firmly fixed. Then, install the servo motor 7 on the mounting plate 5, positioning the output shaft of the servo motor 7 within the U-groove 6. Adjust the position of the servo motor 7 to ensure that the coaxiality error between its output shaft and the mounting hole of the rotating arm 8 is within ±0.1 mm. Then, use bolts to fasten the servo motor 7 to the mounting plate 5. Next, install the rotating arm 8 onto the output shaft of the servo motor 7 using a key connection and nut, completing the installation of the rotating arm 8 and related drive structure. Next, install motor 2 on the mounting base of rotating arm 8, ensuring that the output shaft of motor 2 is aligned with the convex mounting hole 3 of the alignment roller 1. Then, insert the output shaft of motor 2 into the convex mounting hole 3. At this time, the clamping plate 402 in the mounting structure 4 automatically engages with the clamping groove 405 under the action of the first spring 404, completing the connection between motor 2 and alignment roller 1. Finally, install components such as movable plate 12, vertical rod 14, sleeve 15, and spring mechanism 16 to ensure that the connection between components is stable and the movement is smooth.

[0038] Normal operation phase: When the belt conveyor is running normally, the conveyor belt runs on the alignment roller 1, which supports the conveyor belt by its own rotation. At this time, if the conveyor belt does not deviate, the rotating arm 8 is at the initial installation angle, the servo motor 7 does not move, the limit shaft 11 on the mounting plate 5 and the movable groove 13 of the movable plate 12 remain relatively stationary, the spring mechanism 16 is also in its natural state, and the internal telescopic rod 162 maintains a certain extension length under the action of the second spring 165. The universal seat 163 and the universal ball 164 are in their initial positions, and the ball bearings 167 in the rotating cavity 166 do not rotate significantly.

[0039] Conveyor belt misalignment stage: Once the conveyor belt misaligns, when the misalignment reaches a certain level (generally set at 5%-10% of the conveyor belt width, for example, 50-100mm when the conveyor belt width is 1000mm), sensors installed near the conveyor belt (such as photoelectric sensors or contact limit switches) detect the misalignment signal and transmit it to the control system. Upon receiving the signal, the control system immediately starts the servo motor 7. The servo motor 7 precisely adjusts the rotation angle according to the magnitude and direction of the misalignment, following a preset control algorithm. For example, if the conveyor belt misaligns to the right, the servo motor 7 drives the rotating arm 8 to rotate counterclockwise by a certain angle. The magnitude of the rotation angle is calculated by the PID algorithm of the control system based on the misalignment, generally between 5° and 15°. During the rotation of the rotating arm 8, the limiting shaft 11 on the mounting plate 5 and the movable groove 13 of the movable plate 12 cooperate to limit the rotation of the rotating arm 8, preventing excessive rotation. Meanwhile, the movable plate 12 is connected to the spring mechanism 16 via the vertical rod 14 and the sleeve 15. As the rotating arm 8 rotates, the vertical rod 14 slides within the sleeve 15. The telescopic rod 162 in the spring mechanism 16 adaptively adjusts its length under the action of the second spring 165. The universal seat 163 and the universal ball 164 rotate accordingly according to the change in rotation angle. The ball bearings 167 in the rotating cavity 166 also roll, reducing friction during rotation and ensuring the stability and flexibility of the entire structure during rotation. At this time, the alignment roller 1 changes its angle under the drive of the rotating arm 8, generating lateral friction with the conveyor belt. The magnitude of this lateral friction is determined by factors such as the rotation angle of the alignment roller 1, the tension of the conveyor belt, and the running speed, and is generally between 50-200N. This lateral friction drives the conveyor belt to move towards the center position, achieving the alignment correction function.

[0040] Correction Completion Stage: As the conveyor belt gradually returns to the center position under the action of the alignment roller 1, and the deviation is less than the set threshold (generally set to 2%-3% of the conveyor belt width), the sensor detects that the conveyor belt has returned to the normal position and transmits a signal to the control system. After receiving the signal, the control system controls the servo motor 7 to reverse, driving the rotating arm 8 and the alignment roller 1 back to the initial position, completing one correction process. During this process, the spring mechanism 16 gradually returns to its natural state, preparing for the next possible correction action.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0042] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in this invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A frictional dancer roller comprising a dancer roller (1), a motor (2) and a convex mounting hole (3), characterized in that: The convex mounting hole (3) is opened in the adjusting roller (1), the output shaft of the motor (2) is inserted into the convex mounting hole (3), and an installation structure (4) is installed between the output shaft of the motor (2) and the convex mounting hole (3). The number of the installation structures (4) is not less than four, and the installation structures (4) are distributed in a ring at equal intervals. The installation structure (4) includes a groove (401), a clamping plate (402), a pin (403), a first spring (404), and a slot (405). The groove (401) is formed on the output shaft of the motor (2). The clamping plate (402) is rotatably connected to the groove (401) via a pin (403). The first spring (404) is installed between the clamping plate (402) and the groove (401). The slot (405) is formed in the convex mounting hole (3). The clamping plate (402) is engaged in the slot (405).

2. A frictional dancer roller according to claim 1, characterized in that: The inner side of the eccentric roller (1) is provided with a rotating arm (8), the motor (2) is mounted on the rotating arm (8), the rotating arm (8) is provided with a through hole, and the output shaft of the motor (2) is placed in the through hole.

3. A friction-adjusting idler roller according to claim 2, characterized in that: The inner side of the rotating arm (8) is provided with a mounting plate (5), and a U-shaped groove (6) is provided on the mounting plate (5). A servo motor (7) is mounted on the mounting plate (5), and the output shaft of the servo motor (7) is placed in the U-shaped groove (6). The rotating arm (8) is mounted on the output shaft of the servo motor (7).

4. A frictional dancer roller as claimed in claim 3, characterized in that: A limiting shaft (11) is installed on the mounting plate (5). A movable plate (12) is provided outside the limiting shaft (11). A movable groove (13) is provided on the movable plate (12). The limiting shaft (11) is placed in the movable groove (13). A rotating shaft (18) is installed on the rotating arm (8).

5. A frictional dancer roller as claimed in claim 4, characterized in that: A vertical rod (14) is installed on the movable plate (12). A sleeve (15) is fitted over the vertical rod (14). A spring mechanism (16) is installed in the internal space between the vertical rod (14) and the sleeve (15). A connector (17) is installed on the sleeve (15). The connector (17) is rotatably connected to the rotating arm (8) through a rotating shaft (18).

6. A frictional dancer roller as set forth in claim 3, wherein: Ear plates (9) are installed on the mounting plate (5).

7. A friction-adjusting idler roller according to claim 6, characterized in that: Bolt holes (10) are provided on the ear plate (9).

8. A frictional dancer roller as set forth in claim 5 wherein: The spring mechanism (16) includes a fixed plate (161), a telescopic rod (162) is vertically mounted on the upper end of the fixed plate (161), a universal seat (163) is mounted on the top end of the telescopic rod (162), a universal ball (164) is installed inside the universal seat (163), a second spring (165) is fitted on the outside of the telescopic rod (162), and rotating cavities (166) are evenly spaced along the axis of the inner wall of the universal seat (163), and ball bearings (167) are installed inside the rotating cavities (166).

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