Continuous spraying device for aluminum profile anti-corrosion electrostatic spraying powder

Abstract

The invention discloses a continuous spraying device for aluminum profile anti-corrosion electrostatic spraying powder, and belongs to the field of aluminum profile surface treatment. The spraying device comprises a workbench, a rectangular-plate-shaped aluminum profile is arranged on the workbench, a mounting groove is formed in the upper end of the aluminum profile, a limiting block is fixed to the workbench and used for conducting contact limiting on one side of the aluminum profile, and two clamping plates capable of synchronously and reversely sliding are arranged on the workbench and used for centering and clamping the aluminum profile. A mounting frame capable of sliding in the length direction of the mounting groove is arranged at the upper end of the workbench, a connecting frame capable of ascending and descending is arranged on the mounting frame, a scraping plate is fixed to the lower end of the connecting frame, a scraping block capable of ascending and descending and being matched with the mounting groove is arranged on the scraping plate, and when the scraping plate makes contact with the upper surface of the aluminum profile, the scraping block makes contact with and is matched with the inner bottom face of the mounting groove; a dust blowing assembly is arranged on the rear side of the connecting frame; a fixing frame capable of sliding in the length direction of the mounting groove is arranged on the workbench, and a plurality of spray guns evenly distributed in the direction perpendicular to the sliding direction of the fixing frame are arranged on the fixing frame.

Description

Technical Field

[0001] The invention belongs to the field of aluminum profile surface treatment, and in particular relates to a continuous spraying device for anti-corrosion electrostatic spraying powder of aluminum profile. Background Art

[0002] Aluminum profiles are susceptible to corrosion in the natural environment, especially when they are exposed to moisture and oxygen; spraying anti-corrosion electrostatic powder can form a protective coating that effectively prevents the intrusion of corrosive substances and greatly enhances the corrosion resistance of aluminum profiles.

[0003] When performing powder spraying, the powder is usually sprayed on the surface of the aluminum profile by connecting a spray gun to a powder electrostatic sprayer through a delivery pipe; however, some aluminum profile surfaces are provided with grooves for later installation, and the grooves are prone to dirt and grime. If dust or impurities adhere to the grooves before spraying, the powder adsorption effect and spraying quality will be affected; therefore, a continuous spraying device for anti-corrosion electrostatic spraying powder for aluminum profiles is proposed. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a continuous spraying device for anti-corrosion electrostatic spraying powder for aluminum profiles, thereby solving the problems in the prior art.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The continuous spraying device of anti-corrosion electrostatic spray powder for aluminum profiles comprises a workbench, on which is arranged an aluminum profile in the shape of a rectangular plate, an installation slot is provided at the upper end of the aluminum profile, a limit block is fixed on the workbench to contact and limit one side of the aluminum profile, and two clamping plates capable of synchronously sliding in opposite directions are arranged on the workbench to center and clamp the aluminum profile;

[0007] The upper end of the workbench is provided with a mounting frame that can slide along the length direction of the mounting groove, the mounting frame is provided with a connecting frame that can be lifted and lowered, a scraper is fixed at the lower end of the connecting frame, and a scraper block that can be lifted and lowered and can cooperate with the mounting groove is provided on the scraper, and when the scraper contacts the upper surface of the aluminum profile, the scraper block contacts and cooperates with the inner bottom surface of the mounting groove;

[0008] A mounting plate is fixed at the rear side of the connecting frame, and a plurality of air blowing pipes are fixed on the mounting plate and are evenly distributed along a direction perpendicular to the sliding direction of the mounting frame, and are used to blow air to the scraped surface of the aluminum profile and the mounting groove;

[0009] A fixing frame which can slide along the length direction of the installation groove is arranged on the workbench, and a plurality of spray guns which are evenly distributed along a direction perpendicular to the sliding direction of the fixing frame are arranged on the fixing frame.

[0010] Furthermore, the two clamps are both slidably connected to the workbench, and two first fixed plates are provided at the lower end of the workbench. A rotatable first screw rod is provided between the two first fixed plates, and a first external thread and a second external thread with opposite rotation directions and equal pitches are provided at both ends of the first screw rod, respectively. The first external thread and the second external thread respectively pass through the two clamps and are threadedly connected thereto.

[0011] Furthermore, the thread lead angles of the first external thread and the second external thread are both smaller than the equivalent friction angle.

[0012] Furthermore, the scraper block is slidably connected to the scraper plate in the vertical direction, an adjusting rod is threadedly connected to the scraper plate, and the end of the adjusting rod is rotatably connected to the scraper block; the thread lead angle of the external thread on the adjusting rod is smaller than the equivalent friction angle.

[0013] Furthermore, the scraping block and the scraping plate are both provided with a plurality of through holes.

[0014] Furthermore, the mounting frame is slidably connected to the workbench, and the sliding direction is parallel to the length direction of the mounting groove. Two second fixed plates are provided on the upper end of the workbench, and a second screw rod that can be rotatably connected is provided between the two second fixed plates. The second screw rod passes through the mounting frame and is threadedly connected thereto, and the thread lead angle of the second screw rod is smaller than the equivalent friction angle.

[0015] Furthermore, the fixed frame is slidably connected to the workbench, and the sliding direction is parallel to the length direction of the mounting groove. Two third fixed plates are arranged on the workbench, and a rotatable third screw rod is arranged between the two third fixed plates. The third screw rod passes through the fixed frame and is threadedly connected thereto, and the thread lead angle of the third screw rod is smaller than the equivalent friction angle.

[0016] Furthermore, a gear is fixed to the end of the third screw rod, and a clamping assembly is provided on the workbench to clamp with the gear.

[0017] Furthermore, the engaging assembly includes a support plate fixed on the upper end of the workbench, a sliding plate is provided on one side of the support plate, and a clamping block is fixed on the sliding plate; two guide rods are fixed on the support plate, the guide rods pass through the sliding plate and are slidably connected thereto, and a frustum is provided at the end of the guide rod, and the diameter of the frustum is larger than the diameter of the guide rod; a spring is sleeved on the guide rod, and the two ends of the spring are respectively in contact with the support plate and the sliding plate, and under the elastic force of the spring, the sliding plate can be tightly attached to the frustum, and at this time the clamping block is engaged with two adjacent teeth of the gear.

[0018] Furthermore, a connecting block is provided on the mounting frame, and when the mounting frame moves from the initial position to the terminal position, the connecting block can contact the sliding plate and drive the clamping block to leave the gear, and when the mounting frame reaches the terminal position, the clamping block just leaves the gear.

[0019] Beneficial effects of the present invention:

[0020] 1. The aluminum profile is positioned and fixed by setting a clamping assembly and a limit block on the workbench, and a scraper assembly is set to scrape the surface of the aluminum profile and the inside of the installation groove at the same time. At the same time, a dust blowing assembly is set behind the scraper assembly to blow dust from the scraped aluminum profile surface and the installation groove to ensure the cleanliness of the aluminum profile and the quality of powder spraying.

[0021] 2. By setting a locking assembly on the workbench to limit the operation of the spray assembly, and setting a connecting block in the scraper assembly to control the position state of the locking assembly, the operating timing of the spray assembly can be controlled, and the spray assembly can only be operated to perform the spraying operation after the aluminum profile is scraped and dusted, avoiding operating errors that lead to impurities and dust on the surface of the aluminum profile and in the installation groove not being cleaned during spraying, thus affecting the spraying quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a schematic diagram of the overall structure of the spraying device of the present invention;

[0024] Figure 2 It is a schematic diagram of the workbench structure of the present invention;

[0025] Figure 3 This is a schematic structural diagram of the workbench of the present invention from another viewing angle;

[0026] Figure 4 It is a schematic diagram of the structure of the clamping assembly of the present invention;

[0027] Figure 5 It is a schematic diagram of the structure of the scraper assembly of the present invention;

[0028] Figure 6 It is a schematic diagram of the scraper structure of the present invention;

[0029] Figure 7 It is a schematic diagram of the structure of the dust blowing assembly of the present invention;

[0030] Figure 8 It is a schematic diagram of the structure of the spray assembly of the present invention;

[0031] Fig. 9 It is a schematic diagram of the structure of the clamping assembly of the present invention;

[0032] Fig.10 It is a schematic diagram of the support plate structure of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, the continuous spraying device for anti-corrosion electrostatic spraying powder of aluminum profiles includes a workbench 1, a rectangular plate-shaped aluminum profile is placed on the upper end of the workbench 1, and the anti-corrosion electrostatic powder is sprayed on the upper surface of the aluminum profile; and an installation groove is opened on the upper surface of the aluminum profile, and the installation groove needs to be sprayed during spraying.

[0035] like Figure 2 As shown, a limit block 11 is provided at the upper end of the workbench 1, and a clamping assembly 2 is provided on the workbench 1 to center and clamp the aluminum profile, and the limit function of the upper limit block 11 is cooperated to realize the positioning and fixing of the aluminum profile; when spraying aluminum profiles in batches, it is ensured that the position of the installation groove of the aluminum profile is kept highly consistent after each installation, so as to facilitate the cleaning of the installation groove, etc.;

[0036] like Figure 4 As shown, the clamping assembly 2 includes two clamping plates 21 that can slide synchronously in opposite directions, so as to realize the centering clamping of the aluminum profile. When the aluminum profile is installed, one side of the aluminum profile is attached to the limit block 11, and then the two clamping plates 21 are controlled to move closer to each other to realize the positioning and fixing of the aluminum profile.

[0037] In this embodiment, the two clamping plates 21 are slidably connected to the workbench 1. Figure 3 As shown, two first fixed plates 12 are arranged at the lower end of the workbench 1, and a first screw rod 22 is rotatably connected between the two first fixed plates 12. The two ends of the first screw rod 22 are respectively provided with a first external thread 221 and a second external thread 222 with opposite rotation directions and equal pitches. The first external thread 221 and the second external thread 222 respectively penetrate the two clamping plates 21 and are threadedly connected thereto. By arranging a motor on one of the first fixed plates 12 to drive the first screw rod 22 to rotate, the two clamping plates 21 can be synchronously reversely slidable.

[0038] Furthermore, in order to ensure the stability of the clamping of the aluminum profile, the first screw rod 22 needs to have a self-locking property, that is, the thread lead angles of the first external thread 221 and the second external thread 222 are both smaller than the equivalent friction angle.

[0039] Of course, the method of driving the two clamps 21 to slide synchronously in opposite directions includes but is not limited to the first screw rod 22 and other structures in this embodiment. In some embodiments, two cylinders can be set on the workbench 1 to drive the two clamps 21 to slide synchronously in opposite directions respectively.

[0040] A scraper assembly 3 is provided at the upper end of the workbench 1. Figure 5 As shown, the scraper assembly 3 is a mounting frame 31 that can slide along the length direction of the mounting groove at the upper end of the workbench 1, and a cylinder 32 is arranged on the mounting frame 31. A connecting frame 33 is fixed to the end of the driving shaft of the cylinder 32, and a scraper 34 is fixed to the lower end of the connecting frame 33. Under the drive of the cylinder 32, the scraper 34 can contact the upper surface of the aluminum profile, so as to remove and loosen the stubborn impurities attached to the surface of the aluminum profile;

[0041] like Figure 6 As shown, a clearance groove 341 is provided in the middle of the scraper 34, and a scraper 35 capable of adjusting the lifting angle is arranged in the clearance groove 341. The scraper block 35 can cooperate with the mounting groove, and the height of the scraper block 35 can be controlled to adapt to different mounting groove depths, so that the scraper 34 contacts the upper surface of the aluminum profile while the scraper block 35 contacts the bottom surface of the mounting groove. As the mounting frame 31 slides, the stubborn impurities on the surface of the aluminum profile and in the mounting groove can be removed at the same time, so as to facilitate the subsequent dust blowing and cleaning;

[0042] In this embodiment, the scraper block 35 is slidably connected to the scraper plate 34 in the vertical direction, and an adjusting rod 36 is threadedly connected to the scraper plate 34. The end of the adjusting rod 36 is rotatably connected to the scraper block 35. By twisting the adjusting rod 36, the height position of the scraper block 35 can be adjusted; and in order to ensure that the height position of the scraper block 35 remains stable after adjustment, the adjusting rod 36 needs to be self-locking, that is, the thread lead angle of the external thread on the adjusting rod 36 is smaller than the equivalent friction angle.

[0043] A dust blowing assembly 4 is fixed to one side of the connecting frame 33. Figure 7 As shown, the dust blowing assembly 4 includes a mounting plate 41 fixed to the rear side of the connecting frame 33, and a plurality of obliquely arranged air blowing pipes 42 are arranged on the mounting plate 41. The plurality of air blowing pipes 42 are evenly distributed along a sliding direction perpendicular to the mounting frame 31 to blow air on the surface of the aluminum profile after being scraped by the scraper assembly 3, so as to improve the dust blowing effect.

[0044] In addition, in order to ensure that the gas can flow smoothly forward when blowing dust from the surface of the aluminum profile and the installation groove, a plurality of through holes are provided on the scraper block 35 and the scraper plate 34 .

[0045] In this embodiment, the mounting frame 31 is slidably connected to the workbench 1, and the sliding direction is parallel to the length direction of the mounting groove. Two second fixing plates 13 are arranged on the upper end of the workbench 1, and a second screw rod 5 is rotatably connected between the two second fixing plates 13. The second screw rod 5 passes through the mounting frame 31 and is threadedly connected thereto. A motor is arranged on one of the second fixing plates 13 to drive the second screw rod 5 to rotate, so that the sliding position of the mounting frame 31 can be adjusted; and in order to ensure that the sliding position of the mounting frame 31 remains stable after adjustment, the second screw rod 5 needs to have self-locking properties, that is, the thread lead angle of the second screw rod 5 is less than the equivalent friction angle;

[0046] In other embodiments, the mounting frame 31 may be directly driven to slide and adjust by arranging linear drive components such as telescopic rods and hydraulic cylinders on the workbench 1 .

[0047] The workbench 1 is provided with a spraying assembly 6 to spray powder on the surface of the aluminum profile and the inside of the installation groove after scraping and blowing dust; Figure 8 As shown, the spray assembly 6 includes a fixed frame 61 that can slide along the length direction of the installation groove, and a plurality of spray guns 62 are arranged on the fixed frame 61. The spray guns 62 are evenly distributed along a direction perpendicular to the sliding direction of the fixed frame 61. The spray guns 62 are connected to the powder electrostatic sprayer through a conveying pipe, and can spray the powder on the surface of the aluminum profile and in the installation groove;

[0048] In this embodiment, the fixing frame 61 is slidably connected to the workbench 1, and the sliding direction is parallel to the length direction of the installation groove. Two third fixing plates 14 are arranged on the workbench 1, and a third screw rod 7 is rotatably connected between the two third fixing plates 14. The third screw rod 7 penetrates the fixing frame 61 and is threadedly connected thereto. By arranging a motor on one of the third fixing plates 14 to drive the third screw rod 7 to rotate, the sliding position of the fixing frame 61 can be adjusted; and the third screw rod 7 has self-locking property, that is, the thread lead angle of the third screw rod 7 is less than the equivalent friction angle, so as to ensure that the fixing frame 61 remains stable after the position is adjusted;

[0049] In other embodiments, the fixing frame 61 may be directly driven to slide by providing a linear driving component such as a telescopic rod or a hydraulic cylinder on the workbench 1 .

[0050] A gear 8 is fixed to the end of the third screw rod 7, and a clamping assembly 9 is provided on the workbench 1 to clamp with the gear 8 and limit the rotation of the third screw rod 7, thereby limiting the movement and operation of the spray assembly 6;

[0051] like Fig. 9 and Fig.10As shown, the engaging assembly 9 includes a supporting plate 91 fixed to the upper end of the workbench 1, a sliding plate 92 is provided on one side of the supporting plate 91, a clamping block 94 is fixed on the sliding plate 92, and the clamping block 94 can be clamped with two adjacent teeth of the gear 8, thereby limiting the sliding of the fixed frame 61; two guide rods 911 are fixed on the supporting plate 91, the guide rods 911 pass through the sliding plate 92 and are slidably connected thereto, and a round table 912 is provided at the end of the guide rod 911, and the diameter of the round table 912 is larger than the diameter of the guide rod 911; a spring 93 is sleeved on the guide rod 911, and the two ends of the spring 93 are in contact with the supporting plate 91 and the sliding plate 92 respectively. Under the elastic force of the spring 93, the sliding plate 92 can be tightly attached to the round table 912, and at this time, the clamping block 94 is clamped with two adjacent teeth of the gear 8.

[0052] In this embodiment, a connecting block 37 is provided on the mounting frame 31. When the mounting frame 31 moves from the initial position toward the final position (the aluminum profile can be scraped and dusted), the connecting block 37 can contact the sliding plate 92 and drive the clamping block 93 to leave the gear 8, and when the mounting frame 31 reaches the final position, the clamping block 94 just leaves the gear 8, so that the spraying assembly 6 can only be operated to perform the spraying operation after the aluminum profile is scraped and dusted, thereby avoiding impurities and dust on the surface of the aluminum profile and in the mounting groove that are not cleaned during spraying, which affects the spraying quality.

[0053] Working principle:

[0054] By setting a clamping assembly 2 and a limit block 11 on the workbench 1, the aluminum profile is positioned and fixed, and a scraper assembly 3 is set to scrape the surface of the aluminum profile and the inside of the installation groove at the same time. At the same time, a dust blowing assembly 4 is set behind the scraper assembly 3 to blow dust on the scraped aluminum profile surface and the installation groove to ensure the cleanliness of the aluminum profile and the spraying quality of the powder. By setting a clamping assembly 8 on the workbench 1 to limit the operation of the spraying assembly 6, and setting a connecting block 36 in the scraper assembly 3 to control the position state of the clamping assembly 8, the operation timing of the spraying assembly 6 is controlled, and the spraying assembly 6 can only be operated to perform the spraying operation after the aluminum profile is scraped and dusted, so as to avoid operating errors, resulting in impurities and dust on the surface of the aluminum profile and the installation groove being not cleaned during spraying, which affects the spraying quality.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0056] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A continuous spraying device for anti-corrosion electrostatic spray powder for aluminum profiles, comprising a workbench (1), on which a rectangular plate-shaped aluminum profile is arranged, and a mounting groove is provided at the upper end of the aluminum profile, characterized in that: A limit block (11) is fixed on the workbench (1) to limit the contact on one side of the aluminum profile, and two clamping plates (21) capable of synchronously sliding in opposite directions are arranged on the workbench (1) to centrally clamp the aluminum profile; The upper end of the workbench (1) is provided with a mounting frame (31) that can slide along the length direction of the mounting groove, the mounting frame (31) is provided with a connecting frame (33) that can be raised and lowered, a scraper (34) is fixed at the lower end of the connecting frame (33), and a scraper block (35) that can be raised and lowered and can cooperate with the mounting groove is provided on the scraper (34), and the scraper (34) contacts the upper surface of the aluminum profile while the scraper block (35) contacts and cooperates with the inner bottom surface of the mounting groove; A mounting plate (41) is fixed on the rear side of the connecting frame (33), and a plurality of air blowing pipes (42) are fixed on the mounting plate (41) and are evenly distributed along a direction perpendicular to the sliding direction of the mounting frame (31), and are used to blow air on the scraped surface of the aluminum profile and the mounting groove; The workbench (1) is provided with a fixing frame (61) which can slide along the length direction of the installation groove, and the fixing frame (61) is provided with a plurality of spray guns (62) which are evenly distributed along a sliding direction perpendicular to the fixing frame (61).

2. The continuous spraying device of the anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 1 is characterized in that: The two clamping plates (21) are both slidably connected to the workbench (1); two first fixing plates (12) are arranged at the lower end of the workbench (1); a rotatable first screw rod (22) is arranged between the two first fixing plates (12); two ends of the first screw rod (22) are respectively provided with a first external thread (221) and a second external thread (222) with opposite rotation directions and equal pitches; the first external thread (221) and the second external thread (222) respectively penetrate the two clamping plates (21) and are threadedly connected thereto.

3. The continuous spraying device of the anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 2 is characterized in that: The thread lead angles of the first external thread (221) and the second external thread (222) are both smaller than the equivalent friction angle.

4. The continuous spraying device for anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 1 is characterized in that: The scraper block (35) is slidably connected to the scraper plate (34) in the vertical direction; an adjusting rod (36) is threadedly connected to the scraper plate (34); an end of the adjusting rod (36) is rotatably connected to the scraper block (35); and a thread lead angle of the external thread on the adjusting rod (36) is smaller than an equivalent friction angle.

5. The continuous spraying device of anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 1 is characterized in that: The scraping block (35) and the scraping plate (34) are both provided with a plurality of through holes.

6. The continuous spraying device of anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 1 is characterized in that: The mounting frame (31) is slidably connected to the workbench (1), and the sliding direction is parallel to the length direction of the mounting groove. Two second fixing plates (13) are arranged on the upper end of the workbench (1). A second screw rod (5) that can be rotatably connected is arranged between the two second fixing plates (13). The second screw rod (5) passes through the mounting frame (31) and is threadedly connected thereto, and the thread lead angle of the second screw rod (5) is smaller than the equivalent friction angle.

7. The continuous spraying device of anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 1 is characterized in that: The fixing frame (61) is slidably connected to the workbench (1), and the sliding direction is parallel to the length direction of the installation groove. Two third fixing plates (14) are arranged on the workbench (1), and a rotatable third screw rod (7) is arranged between the two third fixing plates (14). The third screw rod (7) passes through the fixing frame (61) and is threadedly connected thereto, and the thread lead angle of the third screw rod (7) is smaller than the equivalent friction angle.

8. The continuous spraying device of the anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 7 is characterized in that: A gear (8) is fixed to the end of the third screw rod (7), and a clamping assembly (9) is provided on the workbench (1) to clamp with the gear (8).

9. The continuous spraying device of anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 8, characterized in that: The clamping assembly (9) comprises a support plate (91) fixed on the upper end of the workbench (1), a sliding plate (92) being arranged on one side of the support plate (91), and a clamping block (94) being fixed on the sliding plate (92); two guide rods (911) being fixed on the support plate (91), the guide rods (911) passing through the sliding plate (92) and being slidably connected thereto, a round table (912) being arranged at the end of the guide rod (911), and the diameter of the round table (912) being larger than the diameter of the guide rod (911); a spring (93) being sleeved on the guide rod (911), and the two ends of the spring (93) being in contact with the support plate (91) and the sliding plate (92) respectively, and under the elastic force of the spring (93), the sliding plate (92) can be closely attached to the round table (912), and at this time, the clamping block (94) is clamped between two adjacent teeth of the gear (8).

10. The continuous spraying device of anti-corrosion electrostatic spraying powder for aluminum profiles according to claim 9, characterized in that: The mounting frame (31) is provided with a connecting block (37). When the mounting frame (31) moves from an initial position to an end position, the connecting block (37) can contact the sliding plate (92) and drive the clamping block (93) to leave the gear (8). Moreover, when the mounting frame (31) reaches the end position, the clamping block (94) just leaves the gear (8).

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