A plastic oral liquid capping device

Abstract

The present invention provides a plastic oral liquid capping device, which belongs to the field of packaging capping. In particular, it relates to a capping device that can be independently installed on the side of a transmission line to form a plastic oral liquid bottle cap package. It includes: a mounting seat, a mounting foot is provided at the bottom of the mounting seat, a U-shaped clamping frame is provided at the top of the mounting seat, and multiple groups of reinforcing connecting rods are provided between the mounting seats. The mounting seats are connected and fixed to fix the capping device on the side of the plastic bottle transmission line; a horizontal adjustment component fixed on the top of the mounting seat; a capping component that is installed at the end of the horizontal adjustment component and can be horizontally telescopically moved; and a cover sleeve that can be detachably placed on the capping component. The capping component includes an outer rotor motor for driving the cover body to rotate. The middle part of the outer rotor motor is provided with an exhaust channel connected to the cover sleeve, and an exhaust port is correspondingly provided. It is fixed by the mounting seat, and the bottle body conveyor belt is arranged to be tightened, which is convenient for installation and setting.

Description

Technical Field

[0001] The present invention provides a plastic oral liquid capping device, belonging to the field of packaging capping, and particularly relates to a capping device that can be independently installed on the side of a transmission line to form a plastic oral liquid bottle cap package. Background Art

[0002] Currently, in the liquid packaging industry, the capping device is used to tighten the bottle cap onto the bottle filled with the product. The capping arm grabs the bottle cap and rotates it to tighten the cap. The existing capping head is a closed-circumference structure. The size of the bottle cap is fixed and cannot be replaced. It is also fixed on the transmission line and cannot be moved, making it inflexible to use.

[0003] Publication No. CN115504418A discloses a screw cap device, comprising a screw cap arm and a screw cap head mounted at the lower end of the screw cap arm, wherein the screw cap arm drives the screw cap head to rise and fall synchronously and rotate synchronously, wherein the screw cap head comprises a push cap member and a screw cap sleeve slidably sleeved on the outer side of the push cap member, and the screw cap sleeve is provided with a vertically extending slide groove, wherein the screw cap device also comprises a push cap plate and a limit sleeve slidably sleeved on the outer side of the screw cap sleeve, wherein the push cap plate is provided with a through hole that slidably cooperates with the screw cap head, and the limit sleeve comprises a limit section located below the push cap plate, the outer diameter of the limit section is larger than the aperture of the through hole, and a pin rod passes through the push cap member, the slide groove and the limit section. The above structure cannot be disassembled and installed, and has poor corresponding effect for different bottle capping structure sizes and cannot be adjusted. Summary of the Invention

[0004] The present invention provides a plastic oral liquid screw capping device, which is provided with a horizontal and vertical adjustment structure and can be adjusted accordingly with the bottle cap. The device has a simple structure and is easy to use.

[0005] The present invention provides a plastic oral liquid capping device, which comprises:

[0006] The mounting base is provided with a mounting foot at the bottom of the mounting base, and a U-shaped fixing frame is provided at the top of the mounting base. Multiple sets of reinforcing connecting rods are provided between the mounting bases, which are connected and fixed by the mounting bases, so that the screw capping device is installed and fixed on the side of the plastic bottle transmission line;

[0007] A leveling assembly is fixed on the top of the mounting base;

[0008] A rotary cover assembly is installed at the end of the horizontal adjustment assembly and can be telescopically moved horizontally; and a cover sleeve is detachably placed on the rotary cover assembly, the rotary cover assembly includes an outer rotor motor for driving the cover body to rotate, the middle part of the outer rotor motor is paved with an exhaust channel connected to the cover sleeve, and a corresponding exhaust port is provided, the cover sleeve corresponds to the card sleeve and is ejected from the cover body, and is engaged with the anti-slip groove on the cover body for transmission, the exhaust port exhausts air and adsorbs the cover body, and the rotary cover assembly includes a vertical adjustment assembly for pushing the cover body up and down;

[0009] A further improvement of the plastic oral liquid screw-capping device of the present invention is that the mounting base includes a first fixing frame and a second fixing frame arranged in parallel, the first fixing frame and the second fixing frame are connected by multiple sets of reinforcing connecting rods, the bottom of the first fixing frame is bent to form an overlapping portion, the second fixing frame is provided with a through groove, the sliding foot is slidably placed in the second fixing frame, the bottom of the sliding foot is bent and parallel to the overlapping portion of the first fixing frame;

[0010] A further improvement of the plastic oral liquid screw capping device of the present invention is that a plurality of groups of limiting grooves are provided on the second fixing frame, an open groove is provided at the bottom of the second fixing frame through the groove, a protrusion structure is provided on the sliding foot and is slidably placed in the open groove, a fastening screw is provided on the protrusion structure, and a pressure plate corresponding to the limiting groove is provided on the fastening screw;

[0011] The sliding foot is adjusted to slide up and down along the second fixing frame, and the tightening screw is locked and tightened on the pressure plate to adjust the clamping width of the sliding foot and the first fixing frame;

[0012] The first fixed plate and the sliding foot are provided with strip holes and circular holes for installation and positioning respectively;

[0013] A fixing frame is provided on the top of the first fixing plate. The fixing frame is a frame structure with one side open. A supporting frame is provided on the top of the second fixing plate. The supporting frame is a T-shaped structure and is fixed to the second fixing plate by screws.

[0014] A further improvement of the plastic oral liquid screw-capping device of the present invention is that the horizontal adjustment component is an electric telescopic component, including a telescopic rod and a telescopic drive unit for adjusting the telescopic rod. A connecting seat is fixedly provided at the end of the telescopic rod, and a connecting ear is provided on the outer wall of the telescopic drive unit. The telescopic drive unit is placed in a fixing frame, and the connecting ears are correspondingly placed on both sides of the fixing frame. The connecting ears are provided with mounting screws for connecting to the fixing frame. The telescopic drive unit is overlapped and placed on a support frame and is fastened to the support frame by screws. A gear and rack transmission is adopted between the telescopic rod and the telescopic drive unit.

[0015] A further improvement of the plastic oral liquid screw-capping device of the present invention is that a U-shaped groove is provided at the end of the telescopic rod, a connecting seat sleeve is placed at the end of the telescopic rod, a V-shaped groove is provided on the side wall of the connecting seat, a fastening bolt passes through the connecting seat and the U-shaped groove, a fastening clip is placed at the end of the telescopic rod, and a connecting ear for connecting the screw-capping assembly is provided on the connecting seat;

[0016] A further improvement of the plastic oral liquid screw-capping device of the present invention is that the screw-capping assembly includes a connecting frame fixedly mounted on a connecting seat, a cylinder mounted on the connecting frame for controlling lifting, and a screw-capping cap movably connected to the end of a pneumatic piston rod. The connecting frame is a C-shaped structure and is fixed to the connecting seat by screws. The cylinder is fixedly arranged on the connecting frame, and the cylinder piston rod extends downward. The screw-capping cap and the clamping groove provided on the end of the piston rod are correspondingly slidably connected. The clamping groove is a T-shaped groove. A top screw is provided on the cross section of the piston rod and is correspondingly abutted against the corresponding buckle structure of the screw-capping cap.

[0017] A further improvement of the plastic oral liquid screw-capping device of the present invention is that a connecting channel is provided on the piston rod of the cylinder, the channel has the piston rod end extending along the axial direction and leading out from the piston rod side wall, the piston rod side wall is provided with an exhaust port connected to the channel, the piston rod end is movably connected with a connecting pipe, the connecting pipe is provided with an outer rotor motor, the connecting pipe and the stator of the outer rotor motor are connected and fixed, the stator of the outer rotor motor is hollow, the rotor is provided with a connecting flange, the stator end is provided with a connecting sleeve, the connecting sleeve is slidably connected to the inside of the stator, and a sealing ring is provided, the screw-cap cap is sleeved on the end of the connecting sleeve, and a cover sleeve corresponding to the bottle cap is provided inside the screw-cap cap;

[0018] A further improvement of the plastic oral liquid screw capping device of the present invention is that a lower transmission tube is provided on the screw cap, an upper transmission tube is provided on the connecting flange, the upper transmission tube and the lower transmission tube are correspondingly spliced for transmission, support springs are provided in the upper transmission tube and the lower transmission tube, and spliced inclined surfaces are provided at the mouths of the upper transmission tube and the lower transmission tube, and the linear surfaces are arranged and extended along the radial direction;

[0019] A further improvement of the plastic oral liquid screw capping device of the present invention is that a sealing sleeve connected to the connecting pipe is provided in the middle of the screw cap, and a plurality of groups of serration structures are provided on the inner wall of the cover sleeve.

[0020] The present invention is used for the screw-cap sealing of the cover of a plastic bottle. The horizontal adjustment component is used to adjust the suspension of the screw-cap component, which is fixed by a mounting seat. One side of the bottle conveyor belt is fastened, which is convenient for installation and setting. The freely installed transmission line moves. By adjusting the horizontal position, it is adjusted and adapted to different bottles. The outer rotor motor rotates to select and close the cover. The upper transmission tube and the lower transmission tube are used in conjunction with the support spring for compression and setting. A channel is formed inside to suck the bottle cap for corresponding adsorption and fastening to avoid falling off and improve the adaptability of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a three-dimensional structural diagram of a plastic oral liquid screw-capping device according to the present invention.

[0022] Figure 2 The figure is a side view of a plastic oral liquid screw capping device according to the present invention.

[0023] Figure 3 The present invention is a structural schematic diagram of a screw capping assembly of a plastic oral liquid screw capping device.

[0024] Figure 4 This is a three-dimensional structural diagram of the connection structure of the screw cap assembly of a plastic oral liquid screw cap device of the present invention.

[0025] Figure 5 The present invention is a three-dimensional structural diagram of a screw cap assembly of a plastic oral liquid screw capping device.

[0026] Figure 6 This is a three-dimensional exploded view of the screw cap assembly of a plastic oral liquid screw cap device of the present invention.

[0027] Figure 7 This is a three-dimensional structural diagram of a mounting base of a plastic oral liquid screw-capping device according to the present invention.

[0028] Figure 8 This is a three-dimensional structural diagram of a horizontal adjustment component of a plastic oral liquid screw capping device according to the present invention.

[0029] Figure 9 This is a three-dimensional structural diagram of a connecting base of a plastic oral liquid screw-capping device according to the present invention.

[0030] Figure 10 The figure is a top view of a screw capping sleeve of a plastic oral liquid screw capping device according to the present invention.

[0031] In the attached figure:

[0032] 1. Mounting base; 2. Horizontal adjustment assembly; 3. Screw cap assembly; 11. First fixing frame; 12. Reinforced connecting rod; 13. Fastening screws; 14. Second fixing frame; 15. Sliding foot; 16. Pressure plate; 17. Clamping frame; 18. Support frame; 21. Telescopic rod; 22. Connecting base; 23. Telescopic drive unit; 31. Cylinder; 32. External rotor motor; 33. Screw cap; 34. Connecting frame; 35. Connecting flange; 311. Clamping groove; 312. Exhaust port; 321. Connecting pipe; 331. Lower transmission pipe; 332. Support spring; 333. Cover sleeve; 334. Sealing sleeve. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings.

[0034] Combined with attachment Figure 1-2 As shown, the plastic oral liquid capping device of the present invention is implemented as follows. The plastic oral liquid capping device of the present invention includes:

[0035] The mounting base 1 is provided with a mounting foot at the bottom, a U-shaped clamping frame 17 is provided at the top of the mounting base 1, and multiple sets of reinforcing connecting rods 12 are provided between the mounting bases 1. The capping device is fixed on the side of the plastic bottle conveyor line by connecting and fixing the mounting bases 1;

[0036] A level adjustment assembly 2 is fixed on the top of the mounting base 1;

[0037] A rotary cover assembly 3 is installed at the end of the horizontal adjustment assembly 2 and can be telescopically moved horizontally; and a cover sleeve 333 is detachably placed on the rotary cover assembly 3. The rotary cover assembly 3 includes an outer rotor motor 32 for driving the cover body to rotate. The middle part of the outer rotor motor 32 is paved with an exhaust channel connected to the cover sleeve 333, and a corresponding exhaust port 312 is provided. The cover sleeve 333 corresponds to the card sleeve outside the cover body and engages with the anti-slip groove outside the cover body for transmission. The exhaust port 312 exhausts and adsorbs the cover body. The rotary cover assembly 3 includes a vertical adjustment assembly for pushing the cover body up and down;

[0038] The present invention relates to a plastic oral liquid screw-capping device that is fixed on one side of a plastic bottle transmission line via a mounting base 1. A horizontal adjustment component 2 is adjusted to extend and retract laterally to change the position of a screw-capping component 3, which is installed and fixed corresponding to the plastic bottle by rotating a cover sleeve 333 with different inner diameters. The device is suitable for adjusting and rotating bottle caps of different sizes. The cover sleeve 333 is synchronously rotated after installation to tighten the cover body and seal the plastic oral liquid.

[0039] Better, such as Figure 7 As shown, the mounting base 1 includes a first fixing frame 11 and a second fixing frame 14 arranged in parallel. The first fixing frame 11 and the second fixing frame 14 are connected by multiple sets of reinforcing connecting rods 12. The bottom of the first fixing frame 11 is bent to form an overlapping portion, which is limited and fastened to the conveyor belt to complete the overall installation setting;

[0040] Preferably, a through groove is provided in the second fixing frame 14, and the sliding foot 15 is slidably placed in the second fixing frame 14. The bottom of the sliding foot 15 is bent and parallel to the overlapping portion of the first fixing frame 11, which is used to slide and adjust the distance between the sliding foot 15 and the first fixing frame 11, so as to perform fixed installation for different installation structures.

[0041] Preferably, the second fixing frame 14 is provided with multiple groups of limiting grooves, the second fixing frame 14 is provided with an open groove at the bottom of the groove, the sliding foot 15 is provided with a protruding structure, and is correspondingly slidably placed in the open groove, the protruding structure is provided with a fastening screw 13, and the fastening screw 13 is provided with a pressure plate 16 corresponding to the limiting groove;

[0042] The sliding foot 15 is adjusted to slide up and down along the second fixing frame 14, and the tightening screw 13 is locked and tightened on the pressure plate 16 to adjust the clamping width of the sliding foot 15 and the first fixing frame 11;

[0043] The first fixing plate and the sliding foot 15 are provided with strip holes and circular holes for installation and positioning, respectively;

[0044] A fixing frame 17 is provided on the top of the first fixing plate. The fixing frame 17 is a frame structure with one side open. A support frame 18 is provided on the top of the second fixing plate. The support frame 18 is a T-shaped structure and is fixed to the second fixing plate by screws.

[0045] Better, such as Figure 8 As shown, the horizontal adjustment assembly 2 is an electric telescopic assembly, including a telescopic rod 21 and a telescopic drive unit 23 for adjusting the telescopic rod 21. A connecting seat 22 is fixedly provided at the end of the telescopic rod 21, and a connecting ear is provided on the outer wall of the telescopic drive unit 23. The telescopic drive unit 23 is placed in the fixing frame 17, and the connecting ears are correspondingly placed on both sides of the fixing frame 17. The connecting ears are provided with mounting screws for connecting to the fixing frame 17. The telescopic drive unit 23 is overlapped and placed on the support bracket 18 and is fastened to the support bracket 18 by screws. A gear and rack transmission is adopted between the telescopic rod 21 and the telescopic drive unit 23;

[0046] Better, such as Figure 9 As shown, the end of the telescopic rod 21 is provided with a U-shaped groove, the connecting seat 22 is sleeved on the end of the telescopic rod 21, the side wall of the connecting seat 22 is provided with a V-shaped groove, the fastening bolt passes through the connecting seat 22 and the U-shaped groove, the fastening clip is placed on the end of the telescopic rod 21, and the connecting seat 22 is provided with a connecting ear for connecting the screw cap assembly 3, which facilitates the disassembly and replacement of the screw cap assembly 3;

[0047] Better, such as Figure 4 As shown, the screw cap assembly 3 includes a connecting frame 34 fixed to the connecting seat 22, a cylinder 31 installed on the connecting frame 34 to control the lifting, and a screw cap 33 movably connected to the end of the pneumatic piston rod. The connecting frame 34 is a C-shaped structure and is fixed to the connecting seat 22 by screws. The cylinder 31 is fixedly provided on the connecting frame 34 accordingly. The piston rod of the cylinder 31 extends downward. The screw cap 33 and the fixing groove 311 provided at the end of the piston rod are correspondingly slidably connected. The fixing groove 311 is a T-shaped groove. The cross section of the piston rod is provided with a top screw, which is correspondingly abutted on the corresponding buckle structure of the screw cap 33 to form a sealing arrangement of the channel combination. Air is exhausted at the exhaust port 312, and the negative pressure adsorbs and fixes the bottle cap.

[0048] Better, such as Figure 3 、 5As shown, a communication channel is provided on the piston rod of the cylinder 31, and the channel has the piston rod end extending axially and leading out from the piston rod side wall. The piston rod side wall is provided with an exhaust port 312 connected to the channel, and the piston rod end is movably connected with a communication pipe 321, and the communication pipe 321 is provided with an outer rotor motor 32, and the communication pipe 321 is fixedly connected to the stator of the outer rotor motor 32. The stator of the outer rotor motor 32 is hollow, and a connecting flange 35 is provided on the rotor. A connecting sleeve is provided at the end of the stator, and the connecting sleeve is slidably connected to the inside of the stator and is provided with a sealing ring. A screw cap 33 is sleeved on the end of the connecting sleeve, and a cover sleeve 333 corresponding to the bottle cap is provided inside the screw cap 33;

[0049] Better, such as Figure 6 As shown, a lower transmission tube 331 is provided on the screw cap 33, and an upper transmission tube is provided on the connecting flange 35. The upper transmission tube and the lower transmission tube 331 are correspondingly spliced for transmission. Support springs 332 are provided in the upper and lower transmission tubes 331. The mouths of the upper and lower transmission tubes 331 are provided with spliced inclined surfaces, and the line surface extends along the radial arrangement.

[0050] Better, such as Figure 10 As shown, a sealing sleeve 334 connected to the connecting pipe is provided in the middle of the screw cap 33, and a plurality of groups of serration structures are provided on the inner wall of the cover sleeve 333, and corresponding adjustment transmission is performed through the serration structures and the cover body.

[0051] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A plastic oral liquid capping device, characterized in that: include: A mounting base (1) is provided with a mounting foot at the bottom of the mounting base (1), a U-shaped clamping frame (17) is provided at the top of the mounting base (1), and multiple groups of reinforcing connecting rods (12) are provided between the mounting bases (1), and the capping device is fixed on the side of the plastic bottle transmission line by connecting and fixing the mounting base (1); A level adjustment assembly (2) fixed to the top of the mounting base (1); A rotary cover assembly (3) is installed at the end of the horizontal adjustment assembly (2) and is capable of horizontal telescopic movement; and a cover sleeve (333) is detachably placed on the rotary cover assembly (3), wherein the rotary cover assembly (3) includes an outer rotor motor (32) for driving the cover body to rotate, a suction channel connected to the cover sleeve (333) is laid in the middle of the outer rotor motor (32), and a corresponding suction port (312) is provided, the cover sleeve (333) is correspondingly clamped outside the cover body, and is engaged with the anti-slip groove outside the cover body for transmission, the suction port (312) sucks air to absorb the cover body, and the rotary cover assembly (3) includes a vertical adjustment assembly for pushing the cover body to move up and down; The screw cap assembly (3) comprises a connecting frame (34) fixedly mounted on the connecting seat (22), a cylinder (31) mounted on the connecting frame (34) for controlling lifting, and a screw cap (33) movably connected to the end of the pneumatic piston rod. The connecting frame (34) is a C-shaped structure and is fixed to the connecting seat (22) by screws. The cylinder (31) is fixedly arranged on the connecting frame (34) accordingly. The piston rod of the cylinder (31) extends downward. The screw cap (33) and the clamping groove (311) arranged at the end of the piston rod are correspondingly slidably connected. The clamping groove (311) is a T-shaped groove. The cross section of the piston rod is provided with a top screw, which is correspondingly abutted on the corresponding buckle structure of the screw cap (33). A communicating channel is provided on the piston rod of the cylinder (31), wherein the channel has a piston rod end extending along the axial direction and leading out from the piston rod side wall, and the piston rod side wall is provided with an exhaust port (312) communicating with the channel, and a communicating pipe (321) is movably connected to the piston rod end, and an outer rotor motor (32) is provided on the communicating pipe (321), and the communicating pipe (321) is fixedly connected to the stator of the outer rotor motor (32), and the stator of the outer rotor motor (32) is hollow, and a connecting flange (35) is provided on the rotor, and a connecting sleeve is provided at the stator end, and the connecting sleeve is slidably connected to the inside of the stator and is provided with a sealing ring, and a screw cap (33) is sleeved on the end of the connecting sleeve, and a cover sleeve (333) corresponding to the bottle cap is provided in the screw cap (33).

2. A plastic oral liquid capping device according to claim 1, characterized in that: The mounting base (1) comprises a first fixing frame (11) and a second fixing frame (14) which are arranged in parallel. The first fixing frame (11) and the second fixing frame (14) are connected by a plurality of groups of reinforcing connecting rods (12). The bottom of the first fixing frame (11) is bent to form an overlap portion. A through groove is provided in the second fixing frame (14). The sliding foot (15) is slidably placed in the second fixing frame (14). The bottom of the sliding foot (15) is bent and parallel to the overlap portion of the first fixing frame (11).

3. A plastic oral liquid capping device according to claim 2, characterized in that: The second fixing frame (14) is provided with a plurality of limiting grooves, and an open groove is provided at the bottom of the second fixing frame (14). A convex structure is provided on the sliding foot (15) and is correspondingly slidably placed in the open groove. A fastening screw (13) is provided on the convex structure, and a pressure plate (16) corresponding to the limiting groove is provided on the fastening screw (13); The sliding foot (15) is adjusted and slid up and down along the second fixing frame (14), and the fastening screw (13) is used to lock the pressure plate (16) to tighten the sliding foot (15) and the first fixing frame (11) to adjust the clamping width.

4. A plastic oral liquid capping device according to claim 2, characterized in that: The first fixing frame (11) and the sliding foot (15) are provided with strip holes and circular holes for installation and positioning, respectively; A fixing frame (17) is provided on the top of the first fixing frame. The fixing frame (17) is a frame structure with one side open. A supporting frame (18) is provided on the top of the second fixing frame. The supporting frame (18) is a T-shaped structure and is fixed on the second fixing frame by screws.

5. The plastic oral liquid capping device according to claim 1, characterized in that: The horizontal adjustment component (2) is an electric telescopic component, comprising a telescopic rod (21), a telescopic drive unit (23) for adjusting the telescopic rod (21), a connecting seat (22) fixedly provided at the end of the telescopic rod (21), a connecting ear provided on the outer side wall of the telescopic drive unit (23), the telescopic drive unit (23) being placed in a clamping frame (17), and the connecting ears being correspondingly placed on both sides of the clamping frame (17), the connecting ears being provided with mounting screws for connecting to the clamping frame (17), the telescopic drive unit (23) being overlapped and placed on a support frame (18), and being fastened to the support frame (18) by screws, and a gear and rack transmission being adopted between the telescopic rod (21) and the telescopic drive unit (23).

6. A plastic oral liquid capping device according to claim 5, characterized in that: The end of the telescopic rod (21) is provided with a U-shaped groove, the connecting seat (22) is sleeved on the end of the telescopic rod (21), the side wall of the connecting seat (22) is provided with a V-shaped groove, the fastening bolts pass through the connecting seat (22) and the U-shaped groove, the fastening clip is placed on the end of the telescopic rod (21), and the connecting seat (22) is provided with a connecting ear for connecting the rotary cover assembly (3).

7. The plastic oral liquid capping device according to claim 1, characterized in that: A lower transmission tube (331) is provided on the screw cap (33), an upper transmission tube is provided on the connecting flange (35), the upper transmission tube and the lower transmission tube (331) are correspondingly spliced for transmission, support springs (332) are provided in the upper transmission tube and the lower transmission tube (331), and spliced inclined surfaces are provided at the mouths of the upper transmission tube and the lower transmission tube (331), and the linear surfaces are extended along the radial direction.

8. The plastic oral liquid capping device according to claim 1, characterized in that: A sealing sleeve (334) connected to the connecting pipe is provided in the middle of the screw cap (33), and a plurality of groups of sawtooth structures are provided on the inner wall of the cover sleeve (333).

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