Wastewater pretreatment system and treatment method for automobile coating electrophoresis

Abstract

The invention discloses a wastewater pretreatment system and a treatment method for automobile coating electrophoresis, and relates to the technical field of wastewater treatment.The wastewater is fed into a sewage pool, then a coagulant is added into the sewage pool, floccules in the wastewater are precipitated, and after the wastewater without the floccules flows out, the coagulant is added into the sewage pool; the motor is started to enable the sewage pool not to be layered at the moment, then the wastewater and the coagulant can be added into the sewage pool again, the wastewater is flocculated again, at the moment, floccules are accumulated and increased under multiple times of precipitation due to layering of the separator, the water outlet is formed in the sewage pool, and the wastewater containing the floccules is discharged. At the moment, because the content of floccules in the wastewater is high, the floccules can be directly collected, the situation that the filter screen is blocked by excessive floccules is avoided, the wastewater flows out more quickly, the situation that a large amount of floccules are left in the sewage pool due to small water flow is avoided, and the wastewater treatment efficiency of the sewage pool is further improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a wastewater pretreatment system and treatment method for automotive coating electrophoresis. Background Technology

[0002] The wastewater from electrophoretic coating of new energy vehicles mainly comes from wastewater generated in processes such as pre-degreasing, degreasing, washing, surface conditioning, phosphating, passivation, electrophoresis, and pure water preparation, as well as some domestic sewage from the factory area. The composition and concentration of each wastewater stream are different, resulting in large variations in wastewater discharge volume and water quality. However, after flocculation of the electrophoretic wastewater, the sediment needs to be filtered. But there is a lot of flocculent material, and the accumulation of flocculent material reduces the filtration speed of the wastewater during filtration, affecting the wastewater treatment effect. Summary of the Invention

[0003] The purpose of this invention is to provide a wastewater pretreatment system and treatment method for automotive coating electrophoresis, so as to overcome the shortcomings of the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: Perform the following steps: S1. Wastewater enters the treatment unit, where large suspended solids are removed by a screen, and the water quality and quantity are balanced in the regulating tank to ensure stable subsequent treatment.

[0005] S2. Wastewater enters the coagulation and sedimentation unit: Coagulants (such as PAC and PAM) are added to form flocs from suspended solids and some heavy metal ions, and the flocs are separated by gravity sedimentation.

[0006] S3. Wastewater enters the biological treatment unit, where some organic matter is degraded through anaerobic treatment, and then further degraded through aerobic treatment. Activated sludge or biofilm processes are commonly used.

[0007] S4. Wastewater enters the advanced treatment unit, where residual suspended solids are removed by filtration, commonly using sand filtration or activated carbon filtration. Then, membrane separation, such as ultrafiltration or reverse osmosis, is performed to remove dissolved organic matter and ions. Finally, adsorption treatment is carried out, such as using activated carbon or resin to adsorb residual organic matter and heavy metals.

[0008] S5. Wastewater enters the sludge treatment unit, where the sludge is first concentrated to reduce its volume, and then dewatered through a filter press or centrifuge for easier subsequent treatment.

[0009] S6. Wastewater enters the disinfection unit and is disinfected by ultraviolet light or ozone to kill pathogenic microorganisms and ensure safe discharge.

[0010] Furthermore, the coagulation and sedimentation unit includes a sewage tank, characterized in that a driving component is provided on the sewage tank, the driving component can drive a plurality of isolation components to rotate, and the plurality of isolation components can cooperate with each other to stratify the sewage tank. The driving component can drive the isolator to move while simultaneously driving the driven component to move; The sewage tank is also equipped with a sealing component, which can seal an opening in the sewage tank. When the driven component moves, it can release the limiting position on the sealing component and, after releasing the limiting position, close the opening by contacting the sealing component.

[0011] Furthermore, the drive assembly includes a motor mounted on the sewage tank, an output gear is provided on the output end of the motor, the output gear meshes with a gear condition, the gear condition is slidably connected to the sewage tank, and the gear condition meshes with a plurality of driven gears.

[0012] Furthermore, several driven gears are respectively and correspondingly arranged at one end of several isolation members. Several isolation members are rotatably connected in the sewage tank. Each isolation member has a side plate on both sides. The side plates of every two adjacent isolation members can fit together. Two mating plates are arranged in the sewage tank. The two mating plates close to the sewage tank can fit together with the two mating plates respectively. Several limiting blocks are arranged on the sewage tank. The limiting blocks correspond to the positions of several isolation members respectively.

[0013] Furthermore, the driven component includes a rubber pad disposed on one end of the rack, one end of a pulsator tube connected to the rubber pad, the other end of the pulsator tube connected to the sewage tank, one end of a first wire connected to the rubber pad, the other end of the first wire rotating with a drive shaft, one end of the drive shaft rotatably connected to the sewage tank, and the other end of the drive shaft connected to the output end of a first torsion spring.

[0014] Furthermore, two first winding shafts are rotatably connected to the drive shaft, and the two first winding shafts are respectively connected to one end of two second wires. A second winding shaft is sleeved on the drive shaft, and one end of a third wire is connected to the second winding shaft.

[0015] Furthermore, the sealing assembly includes two second torsion springs fixed on the sewage tank. The output ends of the two second torsion springs are connected to a sealing plate, which corresponds to the opening position. A sealing gasket is provided on the sealing plate. The sealing plate is connected to the end of the third wire away from the second winding shaft, and the third wire is in a relaxed state.

[0016] Furthermore, the sealing assembly also includes two telescopic sleeves disposed on the sewage tank, each of the two telescopic sleeves being provided with a spring element, and two limiting elements being respectively disposed at the output ends of the plurality of spring elements, with the two limiting elements corresponding to the position of the sealing plate.

[0017] Furthermore, the ends of the two second wires away from the first winding shaft pass through the two telescopic sleeves respectively, and the ends of the two second wires located on the first winding shaft are respectively connected to the two limiting members one by one, and the two second wires are in a taut state.

[0018] Furthermore, the sealing assembly also includes three spring telescopic members disposed on the sewage tank, and each of the three spring telescopic members has an mounting member at its output end, on which a roller is rotatably connected.

[0019] In the above technical solution, the present invention provides a wastewater pretreatment system and treatment method for automotive coating electrophoresis. Wastewater is fed into a wastewater tank, and then a coagulant is added to the wastewater tank to cause the flocculants in the wastewater to settle. Then, a motor is started to separate the wastewater in the tank into layers, and simultaneously, the opening on the wastewater tank is opened to allow the wastewater with the flocculants removed to flow out. After the wastewater with the flocculants removed has flowed out, the motor is started again to prevent the wastewater from separating into layers. Wastewater and coagulant can then be added to the wastewater tank again to cause the wastewater to flocculate again. Simultaneously, some coagulant may still remain in the previously separated water, allowing the residual coagulant to react with the new... The wastewater reacts with each other to reduce the waste of coagulant. At this time, due to the stratification of the separator, the flocculated material accumulates more and more in the stratified wastewater after multiple sedimentation. When it is about to come into contact with the separator, the wastewater containing flocculated material is discharged by setting an outlet on the wastewater tank. At this time, because the flocculated material content in the wastewater is dense, it can be collected directly without the need for filtration. This avoids the situation where too much flocculated material clogs the filter screen, making the wastewater flow out faster and preventing the situation where a large amount of flocculated material remains in the wastewater tank due to the small water flow. This further improves the wastewater treatment efficiency of the wastewater tank. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is one of the overall structural schematic diagrams provided in the embodiments of the present invention; Figure 2This is the second overall structural schematic diagram provided for an embodiment of the present invention; Figure 3 This is a schematic diagram of the internal structure provided in an embodiment of the present invention; Figure 4 Provided for embodiments of the present invention Figure 3 A magnified structural diagram at point A; Figure 5 This is a partial structural schematic diagram provided for an embodiment of the present invention; Figure 6 This is a partial structural cross-sectional schematic diagram provided for an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Sewage tank; 11. Mating plate; 12. Limiting block; 2. Drive assembly; 21. Motor; 22. Output gear; 23. Gear condition; 24. Driven gear; 3. Isolating component; 31. Side plate; 4. Driven assembly; 41. Rubber pad; 42. Impeller tube; 43. First guide wire; 44. Drive shaft; 45. First torsion spring; 46. First winding shaft; 47. Second guide wire; 48. Second winding shaft; 49. Third guide wire; 5. Sealing assembly; 51. Second torsion spring; 52. Sealing plate; 53. Sealing gasket; 54. Telescopic sleeve; 55. Spring component; 56. Limiting component; 57. Spring telescopic component; 58. Mounting component; 59. Roller. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] Please see Figure 1-6 The wastewater pretreatment system and treatment method for automotive coating electrophoresis provided in this embodiment of the invention comprises the following steps: S1. Wastewater enters the treatment unit, where large suspended solids are removed by a screen, and the water quality and quantity are balanced in the regulating tank to ensure stable subsequent treatment.

[0025] S2. Wastewater enters the coagulation and sedimentation unit: Coagulants (such as PAC and PAM) are added to form flocs from suspended solids and some heavy metal ions, and the flocs are separated by gravity sedimentation.

[0026] S3. Wastewater enters the biological treatment unit, where some organic matter is degraded through anaerobic treatment, and then further degraded through aerobic treatment. Activated sludge or biofilm processes are commonly used.

[0027] S4. Wastewater enters the advanced treatment unit, where residual suspended solids are removed by filtration, commonly using sand filtration or activated carbon filtration. Then, membrane separation, such as ultrafiltration or reverse osmosis, is performed to remove dissolved organic matter and ions. Finally, adsorption treatment is carried out, such as using activated carbon or resin to adsorb residual organic matter and heavy metals.

[0028] S5. Wastewater enters the sludge treatment unit, where the sludge is first concentrated to reduce its volume, and then dewatered through a filter press or centrifuge for easier subsequent treatment.

[0029] S6. Wastewater enters the disinfection unit and is disinfected by ultraviolet light or ozone to kill pathogenic microorganisms and ensure safe discharge.

[0030] Preferably, the coagulation sedimentation unit includes a sewage tank 1, and a drive component 2 is provided on the sewage tank 1. The drive component 2 can drive a number of isolation components 3 to rotate, and the number of isolation components 3 can cooperate with each other to stratify the sewage tank 1. The driving component 2 can drive the isolator 3 to move while simultaneously driving the driven component 4 to move; The sewage tank 1 is also equipped with a sealing component 5, which can seal an opening in the sewage tank 1; When the driven component 4 moves, it can release the limiting position on the sealing component 5, and after the limiting position is released, it closes the opening of the contact sealing component 5.

[0031] Preferably, the drive assembly 2 includes a motor 21 mounted on the sewage tank 1, an output gear 22 mounted on the output end of the motor 21, the output gear 22 meshing with a gear condition 23, the gear condition 23 being slidably connected to the sewage tank 1, and the gear condition 23 meshing with a plurality of driven gears 24.

[0032] Preferably, a plurality of driven gears 24 are respectively and correspondingly arranged at one end of a plurality of isolation members 3. The plurality of isolation members 3 are rotatably connected in the sewage tank 1. Each side of the isolation member 3 is provided with a side piece 31. The side pieces 31 of each pair of isolation members 3 can fit together. Two mating pieces 11 are provided in the sewage tank 1. The two mating pieces 11 close to the sewage tank 1 can fit together with the two mating pieces 11 respectively. A plurality of limiting blocks 12 are provided on the sewage tank 1. The plurality of limiting blocks 12 correspond to the positions of the plurality of isolation members 3. The starting motor 21 drives the output gear 22 to rotate, so that the gear condition 23 slides, which drives the plurality of driven gears 24 to rotate, so that the plurality of isolation members 3 start to rotate 90 degrees, which drives the plurality of side pieces 31 to fit together in pairs, and so that the two side pieces 31 fit together with the two mating pieces 11, so that the sewage in the sewage tank 1 is stratified, preventing the outflow of wastewater from carrying out the flocculated material.

[0033] Preferably, the driven component 4 includes a rubber pad 41 disposed on one end of a rack, one end of a pulsator tube 42 connected to the rubber pad 41, the other end of the pulsator tube 42 connected to the sewage tank 1, one end of the rubber pad 41 connected to a first wire 43, the other end of the first wire 43 rotating with a drive shaft 44, one end of the drive shaft 44 rotatably connected to the sewage tank 1, and the other end of the drive shaft 44 connected to the output end of a first torsion spring 45. The sealing is achieved through the cooperation of the rubber pad 41 and the pulsator tube 42, so that the wastewater will not flow out.

[0034] Preferably, two first winding shafts 46 are rotatably connected to the drive shaft 44, and the two first winding shafts 46 are respectively connected to one end of two second wires 47. A second winding shaft 48 is sleeved on the drive shaft 44, and one end of a third wire 49 is connected to the second winding shaft 48.

[0035] Preferably, the sealing assembly 5 includes two second torsion springs 51 fixed on the sewage tank 1. The output ends of the two second torsion springs 51 are connected to a sealing plate 52. The sealing plate 52 corresponds to the opening position. A sealing gasket 53 is provided on the sealing plate 52. The sealing plate 52 is connected to the end of the third wire 49 away from the second winding shaft 48. The third wire 49 is in a relaxed state.

[0036] Preferably, the sealing assembly 5 further includes two telescopic sleeves 54 disposed on the sewage tank 1, each of the two telescopic sleeves 54 being provided with a spring element 55, and two limiting elements 56 being disposed at the output ends of a plurality of spring elements 55, and the two limiting elements 56 being positioned corresponding to the sealing plate 52.

[0037] Preferably, the ends of the two second wires 47 away from the first winding shaft 46 pass through the two telescopic sleeves 54 respectively. The ends of the two second wires 47 located on the first winding shaft 46 are respectively connected to the two limiting members 56. The two second wires 47 are in a taut state. When the gear condition 23 slides, it drives the rubber pad 41 to slide, causing the second wires 47 to relax. At this time, the first torsion spring 45 begins to wind, driving the transmission shaft 44 to start rotating, causing the two first winding shafts 46 to rotate, driving the two second wires 47 to be wound, causing the two limiting members 56 to be pulled, causing the two springs 55 to contract, so that the two limiting members 56 no longer contact the closing plate 52. Then, the relaxed third wire 49 tightens and is driven to be wound by the rotation of the second winding shaft 48, causing the closing plate 52 to rotate. At this time, the opening on the sewage tank 1 is opened, allowing the wastewater for removing flocculants to flow out. After the wastewater for removing flocculants has flowed out, the motor 21 is started to drive the output gear to rotate. This causes the gear condition 23 to slide, driving several driven gears 24 to rotate, causing several isolation components 3 to rotate and reset, so that the sewage tank 1 is no longer stratified. Then, wastewater and coagulant can be added to the sewage tank 1 again, causing the wastewater to flocculate again. At the same time, there may still be coagulant residue in the water that was previously stratified, allowing the residual coagulant to react with the new wastewater, thus reducing the waste of coagulant. At this time, due to the stratification of the isolation components 3, the flocculated material accumulates more and more in the stratified wastewater after multiple sedimentation, until it is about to come into contact with the isolation components 3. By setting an outlet on the sewage tank 1, the wastewater containing flocculated material is discharged. At this time, because the flocculated material content in the wastewater is dense, it can be collected directly without the need for filtration, avoiding the situation where too much flocculated material clogs the filter screen. This makes the wastewater flow out faster and prevents the situation where a large amount of flocculated material remains in the sewage tank 1 due to the small water flow, further improving the wastewater treatment efficiency of the sewage tank 1.

[0038] Preferably, the sealing assembly 5 further includes three spring telescopic members 57 disposed on the sewage tank 1. The output end of the three spring telescopic members 57 is provided with a mounting member 58. A roller 59 is rotatably connected to the mounting member 58. The arrangement of the spring telescopic members 57 and the roller 59 allows the sealing gasket 53 to be compressed by the roller pressing on the inclined surface of one side of the sealing plate 52 when the sealing plate 52 rotates to the reset position. At this time, the two limiting members 56 reset to limit the sealing plate 52, so that the sealing gasket 53 is always in a compressed state, thereby improving the sealing effect.

[0039] Working principle: Wastewater is sent into sewage tank 1, and then coagulant is added to sewage tank 1 to cause the flocculent matter in the wastewater to settle. Then, the motor 21 is started to drive the output gear 22 to rotate, causing the gear condition 23 to slide, which drives several driven gears 24 to rotate, causing several isolation parts 3 to rotate 90 degrees, causing several side pieces 31 to fit together in pairs, and causing two side pieces 31 to fit together with two mating pieces 11, so that the sewage in sewage tank 1 is stratified. Simultaneously, when the tooth condition 23 slides, it drives the rubber pad 41 to slide, causing the second wire 47 to loosen. At this time, the first torsion spring 45 begins to wind, driving the transmission shaft 44 to start rotating, causing the two first winding shafts 46 to rotate, driving the two second wires 47 to be wound, causing the two limiting members 56 to be pulled, driving the two spring members 55 to contract, so that the two limiting members 56 no longer contact the closing plate 52. Then the loosened third wire 49 tightens, and under the rotation of the second winding shaft 48, the third wire 49 is wound, causing the closing plate 52 to rotate. At this time, the opening on the sewage tank 1 is opened, allowing the wastewater from which the flocculated material is removed to flow out. After the wastewater from which flocculants have been removed flows out, the starting motor 21 drives the output gear to rotate, causing the gear conditioner 23 to slide, which in turn drives several driven gears 24 to rotate, causing several isolation components 3 to rotate and reset. This prevents the wastewater tank 1 from becoming stratified again. Wastewater and coagulant can then be added back to the wastewater tank 1, causing the wastewater to flocculate again. Simultaneously, some coagulant may remain in the previously stratified water, allowing it to react with the new wastewater, thus reducing coagulant waste. At this point, due to the stratification of the isolation components 3, the flocculants... As the stratified wastewater undergoes multiple sedimentation processes, the accumulation of flocculent material increases until it is about to come into contact with the separator 3. At this point, an outlet is installed on the wastewater tank 1 to discharge the wastewater containing flocculent material. Since the flocculent material content in the wastewater is high, it can be collected directly without the need for filtration. This avoids the situation where excessive flocculent material clogs the filter screen, allowing the wastewater to flow out faster and preventing a large amount of flocculent material from remaining in the wastewater tank 1 due to a small water flow. This further improves the wastewater treatment efficiency of the wastewater tank 1.

[0040] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for treating wastewater from automobile coating electrophoresis, comprising the following steps: S1. Wastewater enters the treatment unit, where large suspended solids are removed through the screen, and the water quality and volume are balanced in the regulating pool to ensure stable subsequent treatment; S2, wastewater enters the coagulation and sedimentation unit: coagulants (such as PAC, PAM) are added to form flocs with suspended solids and some heavy metal ions, and the flocs are separated by gravity sedimentation; S3, wastewater enters the biochemical treatment unit, where some organic matter is degraded through anaerobic treatment, and then further degraded through aerobic treatment, usually using activated sludge method or biofilm method; S4, wastewater enters the deep treatment unit, where residual suspended solids are removed by filtration, usually sand filtration, activated carbon filtration, etc., followed by membrane separation such as ultrafiltration and reverse osmosis to remove dissolved organic matter and ions, and finally adsorption treatment, such as using activated carbon or resin to adsorb residual organic matter and heavy metals; S5. The wastewater enters the sludge treatment unit, where the sludge is first concentrated to reduce the sludge volume, and then dehydrated by a filter press or centrifuge for subsequent disposal; S6. Wastewater enters the disinfection unit and is disinfected by ultraviolet light or ozone to kill pathogenic microorganisms and ensure discharge safety.

2. A wastewater pretreatment system for automobile coating electrophoresis is used to implement a wastewater treatment method for automobile coating electrophoresis as claimed in claim 1, characterized in that: The coagulation sedimentation unit comprises a sewage pool (1), characterized in that a driving assembly (2) is provided on the sewage pool (1), the driving assembly (2) can drive a plurality of isolation members (3) to rotate, and the plurality of isolation members (3) can cooperate with each other to layer the sewage pool (1); The driving component (2) drives the isolating component (3) to move and can also drive the driven component (4) to move; The sewage pool (1) is also provided with a sealing component (5), and the sealing component (5) is capable of sealing an opening provided on the sewage pool (1); The driven component (4) is capable of releasing the limit on the sealing component (5) when moving, and after releasing the limit, contacts the sealing component (5) to seal the opening.

3. A wastewater pretreatment system for automobile coating electrophoresis according to claim 2, characterized in that: The driving assembly (2) comprises a motor (21) arranged on the sewage tank (1), an output gear member (22) being arranged on the output end of the motor (21), the output gear member (22) being meshed with a gear member (23), the gear member (23) being slidably connected to the sewage tank (1), and the gear member (23) being meshed with a plurality of driven gears (24).

4. A wastewater pretreatment system for automobile coating electrophoresis according to claim 3, characterized in that: The plurality of driven gears (24) are respectively arranged at one end of the plurality of isolation members (3) in a one-to-one correspondence, and the plurality of isolation members (3) are all rotatably connected in the sewage pool (1). A side piece (31) is respectively arranged on both sides of the isolation member (3), and the side pieces (31) adjacent to each other of the two isolation members (3) can fit together. Two matching pieces (11) are arranged in the sewage pool (1), and the two matching pieces (11) close to the sewage pool (1) can respectively fit together with the two matching pieces (11) in a one-to-one correspondence. The sewage pool (1) is provided with a plurality of limit blocks (12), and the plurality of limit blocks (12) respectively correspond to the positions of the plurality of isolation members (3).

5. A wastewater pretreatment system for automobile coating electrophoresis according to claim 4, characterized in that: The driven component (4) comprises a rubber pad (41) arranged on one end of the rack, one end of a pulsator tube (42) is connected to the rubber pad (41), the other end of the pulsator tube (42) is connected to the sewage tank (1), the rubber pad (41) is connected to one end of a first wire (43), the other end of the first wire (43) is rotatable with a transmission shaft (44), one end of the transmission shaft (44) is rotatably connected to the sewage tank (1), and the other end of the transmission shaft (44) is connected to the output end of a first torsion spring member (45).

6. A wastewater pretreatment system for automobile coating electrophoresis according to claim 5, characterized in that: The transmission shaft (44) is rotatably connected to two first winding shafts (46), and the two first winding shafts (46) are respectively connected to one end of two second wires (47) in a one-to-one correspondence. A second winding shaft (48) is sleeved on the transmission shaft (44), and one end of a third wire (49) is connected to the second winding shaft (48).

7. A wastewater pretreatment system for automobile coating electrophoresis according to claim 6, characterized in that: The sealing assembly (5) comprises two second torsion spring members (51) fixed on the sewage pool (1), the output ends of the two second torsion spring members (51) are connected to a closing plate (52), the closing plate (52) corresponds to the opening position, a sealing gasket (53) is arranged on the closing plate (52), the closing plate (52) is connected to an end of the third wire (49) away from the second winding shaft (48), and the third wire (49) is in a relaxed state.

8. A wastewater pretreatment system for automobile coating electrophoresis according to claim 7, characterized in that: The sealing assembly (5) further comprises two telescopic sleeves (54) arranged on the sewage pool (1), spring members (55) being arranged in the two telescopic sleeves (54), two limiting members (56) being arranged at output ends of the spring members (55) respectively, and the two limiting members (56) corresponding to the positions of the closing plate (52).

9. A wastewater pretreatment system for automobile coating electrophoresis according to claim 8, characterized in that: One end of the two second wires (47) away from the first winding shaft (46) passes through the two telescopic sleeves (54) respectively, and one end of the two second wires (47) located on the first winding shaft (46) is connected to the two limit members (56) in a one-to-one correspondence, and the two second wires (47) are in a taut state.

10. A wastewater pretreatment system for automobile coating electrophoresis according to claim 9, characterized in that: The sealing assembly (5) further comprises three spring expansion members (57) arranged on the sewage pool (1), the output ends of the three spring expansion members (57) being provided with a mounting member (58), and a roller (59) being rotatably connected to the mounting member (58).

Images