Coating and shaping equipment for high-breathability PTFE waterproof breathable film

Abstract

The utility model discloses coating and shaping equipment for a high-breathability PTFE (Polytetrafluoroethylene) waterproof breathable film, which comprises a rack, a base cloth supply device arranged on the rack, a coating device arranged on the rack and used for coating liquid raw materials on base cloth, a first coagulating basin arranged on the rack and below the coating device, and a cloth feeding guide device arranged on the rack and at an outlet of the coating device, the cloth in-pool guiding device comprises a plurality of height-adjustable material guiding frames arranged on the machine frame side by side and a water inlet roller guiding mechanism, input material guiding rollers are arranged on the material guiding frames, a plurality of cloth tensioning transition rollers are arranged in the first coagulating tank in the feeding direction, and the connecting line of all the cloth tensioning transition rollers is in a downwards-protruding arc shape. A water outlet guide roller is arranged at one end, far away from the water inlet roller, of the first coagulating tank; a plurality of heaters and a plurality of temperature sensors are arranged in the first coagulating tank; a tension control device for controlling the tension force of the cloth is arranged on the rack, and a traction pressing vehicle for sending out the cloth is arranged on the discharging side of the tension control device on the rack.

Description

Technical Field

[0001] This utility model relates to a waterproof and breathable fabric manufacturing equipment, and more particularly to a coating and shaping equipment for a highly breathable PTFE waterproof and breathable film. Background Technology

[0002] The fabric of a windproof jacket is generally made of a combination of polyester and nylon. Underneath this outer fabric is a waterproof and breathable membrane, which produces a waterproof, breathable and wear-resistant windproof jacket fabric.

[0003] PTFE membrane is a highly stable waterproof and breathable membrane laminated under the fabric. The membrane contains tens of thousands of capillary pores, which are about one ten-thousandth the size of a water droplet and 700 times larger than a gas molecule. It is waterproof while also having good breathability.

[0004] PTFE membranes are manufactured using a phase separation method, which has the advantages of simple process and low manufacturing cost. However, the coating and shaping equipment that has been disclosed is not good enough, which makes the product prone to bubbles and the number of air pores per unit area of ​​the produced PTFE membrane is relatively small, resulting in poor product performance. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a coating and setting device that can improve the performance of PTFE waterproof and breathable film.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a coating and shaping equipment for a high-permeability PTFE waterproof and breathable film, including a frame, a base fabric supply device on the frame, a coating device for coating liquid raw materials on the base fabric on the frame, a first coagulation tank below the coating device on the frame, a fabric inlet guide device on the frame at the outlet of the coating device, the fabric inlet guide device including several height-adjustable guide frames and a water inlet roller guide mechanism arranged side by side on the frame, an input guide roller on the guide frame, several fabric tension transition rollers arranged along the feeding direction in the first coagulation tank, the line connecting all the fabric tension transition rollers forming a downwardly convex arc shape, a water outlet guide roller at the end of the first coagulation tank away from the water inlet roller; several heaters and several temperature sensors are provided in the first coagulation tank; a tension control device for controlling the fabric tension is provided on the frame, and a traction press for sending the fabric out is provided on the side of the tension control device outlet on the frame.

[0007] As a preferred embodiment, the coating apparatus includes a coating frame mounted on a machine frame, a coating roller rotatably mounted on the coating frame, and a coating power device for driving the coating roller to rotate. A vertically upward-arranged lifting cylinder is hinged to the coating frame, and a lifting bracket is hinged to the coating frame above the coating roller. The end of the lifting bracket is hinged to the end of the piston rod of the lifting cylinder. A doctor blade shaft is hinged to the lifting bracket, and a doctor blade is mounted on the doctor blade shaft. The end of the doctor blade is arc-shaped. An adjustable hydraulic cylinder with adjustable stroke is hinged to the lifting bracket, and the end of the piston rod of the adjustable hydraulic cylinder is hinged to a drive block connected to the doctor blade shaft.

[0008] As a preferred embodiment, the coating rack is hinged with a pair of inverted L-shaped clamping arms, and a top mounting plate is mounted on the two inverted L-shaped clamping arms. The top mounting plate is provided with a pair of guide seats arranged parallel to the fabric roller. A movable seat is slidably connected in the guide seats. The top mounting plate is provided with two back-to-back adjustable material-stopping cylinders that drive the movable seats. The movable seats are provided with mounting brackets, and the mounting brackets are provided with guide rails arranged radially along the fabric roller. The guide rails are provided with pressure blocks that are position-adjustable and press the edge of the base fabric.

[0009] As a preferred embodiment, the coating rack is provided with a limiting device to restrict the position of the first doctor blade holder; the limiting device includes a limiting seat disposed on the coating rack, and the limiting seat is provided with a limiting bolt that pushes against the first doctor blade holder.

[0010] As a preferred embodiment, the coating rack is equipped with a detection device for detecting the edge of the base fabric, and the detection signal of the detection device controls the movement of the piston rod of the material-stopping cylinder.

[0011] As a preferred embodiment, the coating rack is provided with a fine-tuning drive mechanism for fine-tuning the position of the lifting rack. The fine-tuning drive mechanism includes a fine-tuning motor mounted vertically upward on the coating rack, a fine-tuning worm gear mounted on the output shaft of the fine-tuning motor, the fine-tuning worm gear cooperating with a fine-tuning worm wheel mounted on the coating rack, an eccentric shaft connected to the worm wheel shaft of the fine-tuning worm wheel, and a bearing mounted at the other end of the eccentric shaft, the outer ring of the bearing being in free contact with the lower part of the lifting rack.

[0012] As a preferred embodiment, the line connecting all the fabric tensioning transition rollers is a downwardly convex arc with an arc radius in the range of 0.45-0.55.

[0013] As a preferred embodiment, the tension control device includes a connecting seat mounted on a frame, a rotating seat mounted on the connecting seat, a tensioning roller rotatably mounted on the rotating seat, and a tensioning cylinder mounted on the connecting seat that drives the rotating seat to rotate to tension the fabric with an adjustable stroke.

[0014] As a preferred embodiment, the water inlet roller guide mechanism includes a movable seat movably mounted on the first solidification tank and a power mechanism for driving the movable seat to move along the length direction of the first solidification tank. The movable seat is provided with a fixed guide roller, and a roller frame that rotates around the axis of the fixed guide roller is hinged to the movable seat. The roller frame is provided with a water inlet adjusting roller, and the movable seat is provided with an adjusting and limiting mechanism for adjusting the position of the roller frame.

[0015] As a preferred embodiment, the adjustment and limiting mechanism includes an adjusting worm gear disposed on the roller shaft of the fixed guide roller, an adjusting worm cooperating with the adjusting worm gear rotatably disposed on the movable seat, an adjusting handwheel disposed at the end of the adjusting worm gear, and the roller frame disposed on the roller shaft.

[0016] As a preferred embodiment, the power mechanism includes a pair of guide rails disposed on the opening of the first solidification tank, a drive shaft rotatably disposed on the movable seat, a pair of driving rollers cooperating with the guide rails being sleeved on the drive shaft, a drive motor disposed on the movable seat, a drive worm gear connected to the output shaft of the drive motor, a drive worm wheel cooperating with the drive worm gear being disposed on the drive shaft, and at least a pair of driven rollers cooperating with the rails being disposed on the movable seat.

[0017] The beneficial effects of this invention are as follows: In this coagulation and curing equipment, the coating thickness can be precisely controlled by the doctor blade of the coating machine. The adjustable dry height guide frame and the water-entry roller guide mechanism of the fabric entry tank guide device allow the coated base fabric to smoothly enter the coagulation tank, preventing liquid migration. Furthermore, the connection line of the fabric tensioning transition rollers in the coagulation tank is a downward-convex arc with an arc range of 0.45-0.55, ensuring reliable tension of the base fabric within the coagulation tank. This also ensures that the film surface tension on the side furthest from the base fabric is greater than on the other side, facilitating pore formation and resulting in a thin PTFE waterproof and breathable film with dense permeable pores per unit area. Additionally, the water-entry roller guide mechanism avoids air bubble formation by adjusting the base fabric's water entry angle, thus preventing air bubble pores on the film and improving film quality.

[0018] Because a pair of inverted L-shaped clamping arms are hinged to the frame, and a top mounting plate is mounted on the two inverted L-shaped clamping arms, and a pair of guide seats are set on the top mounting plate parallel to the fabric roller, a movable seat is slidably connected in the guide seats, and two adjustable material-stopping cylinders that drive the movable seats are set on the top mounting plate. The movable seat is equipped with a mounting bracket, and the mounting bracket is equipped with a guide rail arranged radially along the fabric roller. The guide rail is equipped with an adjustable material-stopping block, so that even if the base fabric slips left or right, the reliability of the coating operation can be reliably guaranteed.

[0019] Because the frame is equipped with a detection device for detecting the edge of the base fabric, the detection signal of the detection device controls the movement of the piston rod of the material-stopping cylinder, which can control the action of the material-stopping cylinder more quickly and further ensure the reliability of the coating operation.

[0020] Because the frame is equipped with a fine-tuning drive mechanism for fine-tuning the position of the lifting frame, the fine-tuning drive mechanism includes a fine-tuning motor mounted vertically on the frame, a fine-tuning worm gear mounted on the output shaft of the fine-tuning motor, and a fine-tuning worm wheel mounted on the frame. An eccentric shaft is connected to the worm wheel shaft of the fine-tuning worm wheel, and a bearing is mounted at the other end of the eccentric shaft. The outer ring of the bearing is in free contact with the lower part of the lifting frame, which allows for fine-tuning of the position of the lifting frame. This enables precise control of the distance between the scraper and the surface of the base fabric, thereby greatly improving the precise thickness of the fabric liquid layer.

[0021] For the fabric inlet guide device, the height of the guide frame is adjusted to ensure the appropriate tension arc of the base fabric, minimizing the flow of coating material. The position of the roller frame is adjusted by rotating the adjustment handwheel, which changes the position of the water inlet adjustment roller. This causes the angle between the base fabric stretched outside the water inlet adjustment roller and the horizontal plane to change, thus finding a reasonable angle range for the base fabric to enter the tank to avoid air bubble formation, thereby improving the quality of film formation.

[0022] Since the drop height of all the guide rollers on the frame is not less than one-third of the height from the top surface of the coating machine's output roller to the liquid surface of the first solidification tank, the relatively gentle descent of the base fabric makes it difficult for the material coated on its surface to migrate, thus ensuring the quality of the subsequent finished products. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the coating and setting equipment.

[0024] Figure 2 This is a schematic diagram of the front structure of the coating device.

[0025] Figure 3 This is a schematic diagram of the side structure of the coating device.

[0026] Figure 4 This is a schematic diagram of the middle structure of the coating device (some structures are hidden for clarity).

[0027] Figure 5 This is a schematic diagram of the other side of the coating device (some structures are hidden for clarity).

[0028] Figure 6 This is a schematic diagram of the fine-tuning mechanism in the coating device.

[0029] Figure 7 This is a schematic diagram of the fine-tuning mechanism in the coating device from another angle.

[0030] Figure 8 This is a schematic diagram of the fabric feeding guide device.

[0031] Figure 9This is a schematic diagram of the water inlet roller guide mechanism.

[0032] Figure 10 This is a side view of the water inlet roller guide mechanism.

[0033] Figure 11 This is a schematic diagram of the other side of the water inlet roller guide mechanism.

[0034] In the diagram: 1. Frame; 2. Base fabric supply device; 3. Coating device; 4. First coagulation tank; 5. Fabric inlet guide device; 6. Fabric tension transition roller; 7. Water outlet guide roller; 8. Tension control device; 9. Traction press.

[0035] 31 Coating rack, 32 Coating roller, 33 Shovel worm gear, 34 Shovel worm, 35 Adjusting handwheel, 36 Lifting cylinder, 37 Lifting frame, 38 Scraper shaft, 39 Scraper, 310 Adjusting cylinder;

[0036] 311 Inverted L-shaped clamping arm; 312 Top mounting plate; 313 Guide seat; 314 Movable seat; 315 Material blocking cylinder; 316 Mounting bracket; 317 Guide rail; 318 Material blocking block; 319 Detection device; 320 Fine-tuning motor; 321 Fine-tuning worm gear; 322 Fine-tuning worm wheel; 323 Eccentric shaft; 324 Bearing; 325 Limit rod; 326 Limit switch; 327 Limit seat; 328 Limit bolt; 329 Guide roller; 330 Support plate; 331 Adjustment mechanism; 332 Shovel blade;

[0037] 51 Drive motor, 52 Guide frame, 53 Input guide roller, 54 Moving seat, 55 Guide rail, 56 Drive shaft, 57 Drive roller, 58 Adjusting handwheel, 59 Drive worm, 510 Drive worm wheel, 511 Driven roller, 512 Support roller, 513 Fixed guide roller, 514 Roller frame, 515 Water inlet adjusting roller; 516 Adjusting worm wheel, 517 Adjusting worm. Detailed Implementation

[0038] The specific implementation scheme of this utility model will now be described in detail with reference to the accompanying drawings.

[0039] like Figure 1-11As shown, a coating and setting device for a high-permeability PTFE waterproof and breathable film includes a frame 1, a base fabric supply device 2 on the frame 1, a coating device 3 on the frame 1 for coating liquid raw materials onto the base fabric, a first coagulation tank 4 below the coating device 3 on the frame 1, and a fabric inlet guide device 5 at the outlet of the coating device 3 on the frame 1. The fabric inlet guide device 5 includes several height-adjustable guide frames 52 arranged side by side on the frame 1 and a water inlet roller guide mechanism. The guide frames are equipped with input guide rollers 53. Several fabric tension transition rollers 6 are arranged in the first coagulation tank 4 along the feeding direction. The line connecting all the fabric tension transition rollers 6 forms a downwardly convex arc with an arc of 0.45. A water outlet guide roller 7 is provided at the end of the first coagulation tank 4 away from the water inlet roller. Several heaters and several temperature sensors are provided in the first coagulation tank 4.

[0040] The frame 1 is equipped with a tension control device 8 for controlling the tension of the fabric. The tension control device 8 includes a connecting seat mounted on the frame 1, a rotating seat mounted on the connecting seat, a tension roller rotatably mounted on the rotating seat, and a tension cylinder mounted on the connecting seat that drives the rotating seat to rotate to tension the fabric with an adjustable stroke. A traction press 9 for feeding the fabric is provided on the side of the frame 1 where the tension control device 8 exits.

[0041] The coating apparatus 3 includes a coating frame 31 mounted on a frame 1, a coating roller 32 rotatably mounted on the coating frame 31 and a coating power device for driving the coating roller 32 to rotate, a vertically upwardly arranged lifting cylinder 36 hinged to the coating frame 31, a lifting frame 37 hinged above the coating roller on the coating frame 31, the end of the lifting frame 37 being hinged to the end of the piston rod of the lifting cylinder 36; a doctor blade shaft 38 hinged to the lifting frame 37, a doctor blade 39 mounted on the doctor blade shaft 38, the end of the doctor blade 39 being arc-shaped, and a stroke-adjustable adjusting cylinder 310 hinged to the lifting frame 37, the end of the piston rod of the adjusting cylinder 310 being hinged to a drive block connected to the doctor blade shaft 38;

[0042] A pair of inverted L-shaped clamping arms 311 are hinged to the coating rack 31. A top mounting plate 312 is mounted on the two inverted L-shaped clamping arms 311. A pair of guide seats 313 are arranged parallel to the fabric roller on the top mounting plate 312. A movable seat 314 is slidably connected to the guide seats 313. Two adjustable-stroke blocking cylinders 315 are arranged on the top mounting plate 312 to drive the movable seats 314. A detection device 319 for detecting the edge of the base fabric is provided on the coating rack 31. The detection signal of the detection device 319 controls the movement of the piston rod of the blocking cylinder 315. A mounting bracket 316 is provided on the movable seat 314. A guide rail 317 arranged radially along the fabric roller is provided on the mounting bracket 316. A pressing block for pressing the edge of the base fabric is adjustable on the guide rail 317. The coating rack 31 is provided with a limiting device to restrict the position of the first scraper holder; the limiting device includes a limiting seat 327 provided on the coating rack 31, and a limiting bolt 328 on the limiting seat 327 to push against the first scraper holder.

[0043] The coating rack 31 is equipped with a fine-tuning drive mechanism for fine-tuning the position of the lifting rack 37. The fine-tuning drive mechanism includes a fine-tuning motor 320 mounted vertically upward on the coating rack 31. A fine-tuning worm 321 is mounted on the output shaft of the fine-tuning motor 320. The fine-tuning worm 321 cooperates with a fine-tuning worm wheel 322 mounted on the coating rack 31. An eccentric shaft 323 is connected to the worm wheel shaft of the fine-tuning worm wheel 322. A bearing 324 is mounted at the other end of the eccentric shaft 323. The outer ring of the bearing 324 is in free contact with the lower part of the lifting rack 37.

[0044] A guide roller 329 is provided on the coating rack 31 below the coating roller 32. A receiving tray 330 for receiving excess coating is also provided on the coating rack 31 below the coating roller 32, and an adjustment mechanism 331 for adjusting the vertical position of the receiving tray 330 is provided on the coating rack 31. A scraper 332 is provided on the coating rack 31 to remove excess coating from the coating roller 32. The scraper 332 is connected to a scraping worm gear 33 provided on the coating rack 31, and a scraping worm 34 for driving the scraping worm gear 33 to rotate is provided on the coating rack 31. An adjusting handwheel 35 is provided at the end of the scraping worm 34.

[0045] The water inlet roller guide mechanism includes a movable seat 54 movably mounted on the first solidification tank 4 and a power mechanism for driving the movable seat 54 to move along the length of the first solidification tank 4. The power mechanism includes a pair of guide rails 55 mounted on the opening of the first solidification tank 4. A drive shaft 56 is rotatably mounted on the movable seat 54. A pair of driving rollers 57 that cooperate with the guide rails 55 are sleeved on the drive shaft 56. A drive motor 51 is mounted on the movable seat 54. A drive worm gear 59 is connected to the output shaft of the drive motor 51. A drive worm wheel 510 that cooperates with the drive worm gear 59 is mounted on the drive shaft 56. The movable seat 54 also has at least one pair of driven rollers 511 that cooperate with the rails. The movable seat 54 also has a pair of support rollers 512 that cooperate with the rails. A fixed guide roller 513 is provided on the movable base 54. A roller frame 514 that rotates around the axis of the fixed guide roller 513 is hinged to the movable base 54. A water inlet adjusting roller 515 is provided on the roller frame 514. An adjusting and limiting mechanism for adjusting the position of the roller frame 514 is provided on the movable base 54. The adjusting and limiting mechanism includes an adjusting worm gear 516 disposed on the roller shaft of the fixed guide roller 513. An adjusting worm 517 that cooperates with the adjusting worm gear 516 is rotatably disposed on the movable base 54. An adjusting handwheel 58 is provided at the end of the adjusting worm 517. The roller frame 514 is disposed on the roller shaft.

[0046] The above embodiments are merely illustrative of the principles and effects of this utility model, as well as some of its applications, and are not intended to limit this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A coating and setting device for a high-permeability PTFE waterproof and breathable film, comprising a frame, a base fabric supply device on the frame, a coating device for coating the base fabric with liquid raw materials on the frame, a first solidification tank below the coating device on the frame, and a fabric inlet guide device at the outlet of the coating device on the frame, characterized in that: The fabric inlet guiding device includes several height-adjustable guide frames arranged side by side on the frame and an inlet roller guiding mechanism. The guide frames are equipped with input guide rollers. Several fabric tension transition rollers are arranged in the first coagulation tank along the feeding direction. The line connecting all the fabric tension transition rollers forms a downward convex arc shape. The first coagulation tank has an outlet guide roller at the end away from the inlet roller. Several heaters and several temperature sensors are provided in the first coagulation tank. The frame is equipped with a tension control device to control the fabric tension. On the side of the frame where the tension control device is discharging, a traction press is provided to send the fabric out.

2. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 1, characterized in that: The coating apparatus includes a coating frame mounted on a machine frame, a coating roller rotatably mounted on the coating frame, and a coating power device for driving the coating roller to rotate. A vertically upward-arranged lifting cylinder is hinged to the coating frame. A lifting frame is hinged to the coating frame above the coating roller, and the end of the lifting frame is hinged to the end of the piston rod of the lifting cylinder. A scraper shaft is hinged to the lifting frame, and a scraper is mounted on the scraper shaft. The end of the scraper is arc-shaped. An adjustable adjustment cylinder with adjustable stroke is hinged to the lifting frame, and the end of the piston rod of the adjustment cylinder is hinged to a drive block connected to the scraper shaft. A pair of inverted L-shaped clamping arms are hinged to the coating rack. A top mounting plate is mounted on the two inverted L-shaped clamping arms. A pair of guide seats are set on the top mounting plate, which are parallel to the fabric roller. A movable seat is slidably connected in the guide seats. Two adjustable-stroke baffle cylinders that drive the movable seats are set on the top mounting plate. A mounting bracket is set on the movable seat. A guide rail is arranged radially along the fabric roller on the mounting bracket. A pressure block that presses the edge of the base fabric is set on the guide rail with an adjustable position.

3. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 2, characterized in that: The coating rack is provided with a limiting device that restricts the position of the first scraper holder; the limiting device includes a limiting seat provided on the coating rack, and the limiting seat is provided with a limiting bolt that pushes against the first scraper holder.

4. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 2, characterized in that: The coating rack is equipped with a detection device for detecting the edge of the base fabric, and the detection signal of the detection device controls the movement of the piston rod of the material-blocking cylinder.

5. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 2, characterized in that: The coating rack is equipped with a fine-tuning drive mechanism for fine-tuning the position of the lifting rack. The fine-tuning drive mechanism includes a fine-tuning motor mounted vertically upward on the coating rack. A fine-tuning worm is mounted on the output shaft of the fine-tuning motor. The fine-tuning worm engages with a fine-tuning worm wheel mounted on the coating rack. An eccentric shaft is connected to the worm wheel shaft of the fine-tuning worm wheel. A bearing is mounted at the other end of the eccentric shaft. The outer ring of the bearing is in free contact with the lower part of the lifting rack.

6. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 1, characterized in that: The line connecting all the fabric tensioning transition rollers forms a downward-convex arc with an arc radius in the range of 0.45-0.

55.

7. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 1, characterized in that: The tension control device includes a connecting seat mounted on the frame, a rotating seat mounted on the connecting seat, a tensioning roller rotatably mounted on the rotating seat, and a tensioning cylinder mounted on the connecting seat that drives the rotating seat to rotate to tension the fabric with an adjustable stroke.

8. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 1, characterized in that: The water inlet roller guide mechanism includes a movable seat movably mounted on the first solidification tank and a power mechanism for driving the movable seat to move along the length of the first solidification tank. The movable seat is provided with a fixed guide roller, and a roller frame that rotates around the axis of the fixed guide roller is hinged to the movable seat. The roller frame is provided with a water inlet adjusting roller, and the movable seat is provided with an adjusting and limiting mechanism for adjusting the position of the roller frame.

9. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 8, characterized in that: The adjustment and limiting mechanism includes an adjusting worm gear mounted on the roller shaft of the fixed guide roller, an adjusting worm gear rotatably mounted on the movable seat and cooperating with the adjusting worm gear, an adjusting handwheel at the end of the adjusting worm gear, and the roller frame mounted on the roller shaft.

10. The coating and setting equipment for a high-permeability PTFE waterproof and breathable film as described in claim 8, characterized in that: The power mechanism includes a pair of guide rails set on the opening of the first solidification tank, a drive shaft rotatably mounted on the movable seat, a pair of driving rollers that cooperate with the guide rails mounted on the drive shaft, a drive motor mounted on the movable seat, a drive worm gear connected to the output shaft of the drive motor, a drive worm wheel that cooperates with the drive worm gear mounted on the drive shaft, and at least a pair of driven rollers that cooperate with the rails on the movable seat.

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