A scraped-wall thin-film evaporator

Abstract

The present invention discloses a wall-scraping thin-film evaporator, which relates to the technical field of evaporators, and comprises a cylinder, a heating cylinder cover arranged on the outer wall of the cylinder, a top cover arranged on the top end of the cylinder, and a bottom cover arranged on the bottom end of the cylinder, and also comprises a liquid separation plate arranged inside the top cover for detecting the viscosity of waste liquid according to weight and adaptively lifting and lowering, a first scraper and a second scraper arranged on the inner wall of the cylinder for identifying the viscosity of the waste liquid and adaptively switching between two states of efficient wall-scraping evaporation and accelerated material discharge, and a switching mechanism for controlling the switching of the first scraper and the second scraper according to the lifting and lowering of the liquid separation plate. The present invention arranges a liquid separation plate capable of detecting the content of viscous matter in the waste liquid, lifts and lowers the liquid separation plate by utilizing the weight borne on the upper surface of the liquid separation plate, and controls the first scraper and the second scraper to be switched for use by means of the switching mechanism, thereby adaptively switching the first scraper or the second scraper for film scraping evaporation according to the content of viscous matter in the waste liquid, thereby improving the film scraping effect of the waste liquid and the discharge efficiency of the viscous matter.

Description

Technical Field

[0001] The invention relates to the technical field of evaporators, in particular to a scraped-wall thin-film evaporator. Background Art

[0002] In industrial production, chemical waste liquid is often generated. In order to achieve the purpose of resource recycling and reuse, the effective components of the waste stripping liquid are usually recovered. The existing recycling technology generally uses a process combining evaporation and multi-tower distillation, and mainly uses a scraped film evaporator to treat chemical waste liquid.

[0003] The scraper film evaporator is a shell with a heating steam jacket on the outside and a rotatable scraper inside, which is driven by the rotating shaft in the center of the cylinder. After the raw liquid is added tangentially from the top of the evaporator, it forms a downward rotating film along the inner wall of the shell under the drive of gravity and the rotating scraper. The finished liquid is discharged from the bottom discharger, and the secondary steam is discharged from the top after passing through the demister. The outstanding advantage of this evaporator is that it has a strong adaptability to materials and is suitable for the evaporation of high-viscosity, easy-to-crystallize, easy-to-scale, containing suspended matter or heat-sensitive liquids.

[0004] In the prior art, when the scraper is scraping the waste liquid, since the viscosity of the waste liquid entering the evaporator may be different, the waste liquid with low viscosity will flow faster in the evaporator and can form a better film. If the viscosity is higher, it means that there is less evaporable liquid component in the waste liquid. The viscous material will usually adhere to the heating wall, and the viscous material will slide and fall along the heating wall. Since this part of the material has poor fluidity and naturally falls slowly, it will not only affect the discharge efficiency of the viscous material, but also easily accumulate on its end surface as the scraper rotates during scraping, further affecting the scraping effect after the waste liquid enters. Summary of the invention

[0005] The technical solution of the present invention aims at the technical problem that the existing technical solutions are too simple, and provides a solution that is significantly different from the existing technologies. Specifically, the purpose of the present invention is to provide a scraping thin film evaporator to solve the problem mentioned in the above background technology that the viscous substances in the waste liquid have poor fluidity, which not only affects the discharge efficiency of the viscous substances, but also easily accumulates on its end surface as the scraper rotates during scraping, further affecting the scraping effect after the waste liquid enters.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solutions: a scraping thin film evaporator, comprising a cylinder, a heating cylinder cover arranged on the outer wall of the cylinder, a top cover arranged on the top of the cylinder, and a bottom cover arranged on the bottom of the cylinder, and also comprising a liquid separation plate arranged inside the top cover for detecting the viscosity state of the waste liquid according to the weight and adaptively lifting and lowering, a first scraper and a second scraper arranged on the inner wall of the cylinder for identifying the viscosity state of the waste liquid and adaptively switching between the two states of efficient scraping evaporation and accelerated material feeding, and a switching mechanism for controlling the switching of the first scraper and the second scraper according to the lifting and lowering of the liquid separation plate;

[0007] The top surface of the liquid separation plate is configured as a curved surface that slopes downward from the center to the outside, and the curvature of the end surfaces of the first scraper and the second scraper matches the curvature of the inner wall of the cylinder.

[0008] Preferably, a heat source inlet is provided at the upper end of the heating cylinder cover, and a heat source outlet is provided at the lower end of the heating cylinder cover, a liquid inlet is provided at the top center of the top cover, and a steam outlet is provided at the top of the top cover on one side of the liquid inlet, and a concentrated liquid outlet is provided on the bottom outer side of the bottom cover.

[0009] Preferably, a shell is fixed at the inner center of the bottom cover, the top of the shell is rotatably connected to a rotating column extending to the inside of the top cover, the bottom end of the bottom cover is located inside the shell and a motor is installed, and the output end of the motor is fixed to the bottom end of the rotating column.

[0010] Preferably, the rotating column is configured as a hollow structure, and a first spring is fixedly connected to the inner wall of the bottom end of the rotating column, a sliding plate slidably matched with the inner wall of the rotating column is fixedly connected to the top of the first spring, a telescopic rod is connected between the sliding plate and the bottom end of the rotating column, a fixed column is fixedly connected to the upper surface of the sliding plate, the top of the fixed column is fixedly connected to the bottom end of the liquid separating plate, a limiting column is fixed to the outer wall of the liquid separating plate, and a limiting groove slidably matched with the limiting column is vertically opened on the inner wall of the top cover.

[0011] Preferably, the outer wall of the cylinder is evenly distributed with fixed plates, and the fixed plates are symmetrically provided with two groups of movable rods that slide with the fixed plates in the direction toward the inner wall of the cylinder, one end of the two groups of movable rods are respectively fixed to the outer walls of the first scraper and the second scraper, and the inclination angles of the first scraper and the second scraper are symmetrically arranged with respect to the center line of the cylinder, and a switching mechanism extending to the interior of the rotating column is provided inside each group of fixed plates, and the rotation trajectories of the first scraper and the second scraper outside the two longitudinally adjacent groups of fixed plates overlap.

[0012] Preferably, the switching mechanism includes a movable block arranged inside a fixed plate, a fixed rod is fixedly arranged inside the movable block, a connecting rod is arranged between one end of a group of the movable rods and the fixed rod, the connecting rod is rotatably connected to the inner wall of the fixed plate through a rotating shaft, the other end of the fixed rod extends to the outer wall of another group of movable rods and is fixed, sliding grooves are respectively provided at both ends of the connecting rod, and sliding buckles that slidably cooperate with the sliding grooves are respectively provided on the outer wall of a group of the movable rods and one end of the fixed rod.

[0013] Preferably, the switching mechanism also includes a connecting column fixedly connected to the outer wall of the movable block, the end of the connecting column passes through the interior of the rotating column, and a ball is provided at the end of the connecting column, a second spring is fixedly connected between the movable block and the rotating column, and a columnar block fixed to the outer wall of the fixed column is correspondingly provided on one side of the connecting column, and the outer wall of the columnar block is provided with an inner groove that slides with the connecting column.

[0014] Preferably, the inner groove includes a first groove opened vertically and a second groove opened toward the center of the columnar block, and the surface connecting the second groove and the first groove is set as an inclined surface, and a limiting ring fixed to the inner wall of the rotating column is set below the columnar block.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention provides a liquid separation plate that can detect the viscous material content in the waste liquid, uses the weight borne by the upper surface of the liquid separation plate to raise and lower it, and controls the first scraper and the second scraper to switch between them through a switching mechanism, thereby adaptively switching the first scraper or the second scraper according to the viscous material content in the waste liquid to perform scraping evaporation, thereby improving the scraping effect of the waste liquid.

[0017] According to the present invention, when the content of viscous matter in the waste liquid is within a certain range, the components with high fluidity in the waste liquid continue to flow along the curved surface on the liquid separation plate, wherein the viscous substances with poor fluidity flow slowly on the liquid separation plate, and this part of the viscous substances will increase the weight of the liquid separation plate, and the liquid separation plate drives the sliding plate to slide downward and squeeze the first spring through the connecting column, and the connecting column drives the columnar block of the outer wall to move downward, and the connecting column slides in the inner groove formed by the first groove and the second groove. During the sliding process of the connecting column in the first groove, the film is scraped by the second scraper. Since the second scraper is inclined and the range of the second scrapers adjacent to each other in the longitudinal direction overlaps when rotating, when the second scraper scrapes the waste liquid to form a film, after the waste liquid flows downward along the inner wall of the cylinder, the second scraper from top to bottom will produce an upward pushing effect, thereby slowing down the downward flow speed of the waste liquid when it flows downward, and further improving the scraping evaporation effect of the waste liquid.

[0018] When the cam is in the state of being moved along the axis of the cylinder, the second end of the cylinder is moved along the axis of the cylinder, and the second end of the cylinder is moved along the axis of the cylinder to move the cam, so that the cam can move smoothly and the cam can move smoothly, thereby the cam can move smoothly and the cam can move smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A perspective view of the present invention;

[0020] Figure 2 It is a cross-sectional perspective view of the present invention;

[0021] Figure 3 It is a plan cross-sectional view of the present invention;

[0022] Figure 4 It is a top cross-sectional view of the present invention;

[0023] Figure 5 It is a planar cross-sectional view of the rotating column of the present invention;

[0024] Figure 6 is a cross-sectional perspective view of a columnar block of the present invention;

[0025] Figure 7 For the present invention Figure 3 A in the enlarged view;

[0026] Figure 8 For the present invention Figure 5 The enlarged view of point B in the figure;

[0027] Fig. 9 For the present invention Figure 4 Enlarged view of point C in the figure.

[0028] In the figure: 1. cylinder; 2. heating cylinder cover; 21. heat source inlet; 22. heat source outlet; 23. top cover; 24. liquid inlet; 25. steam outlet; 26. bottom cover; 27. concentrate outlet; 3. outer shell; 4. rotating column; 5. motor; 6. first spring; 61. sliding plate; 62. telescopic rod; 63. fixed column; 64. liquid separation plate; 7. fixed plate; 71. movable rod; 72. first scraper; 73. second scraper; 74. movable block; 75. fixed rod; 76. connecting rod; 77. slide groove; 78. slide buckle; 79. connecting column; 710. second spring; 8. columnar block; 81. inner groove; 82. limit ring. DETAILED DESCRIPTION

[0029] 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.

[0030] See also Figures 1 to 9 The present invention provides a technical solution: a scraping thin film evaporator, comprising a cylinder 1, a heating cylinder cover 2 arranged on the outer wall of the cylinder 1, a top cover 23 arranged on the top of the cylinder 1 and a bottom cover 26 arranged on the bottom of the cylinder 1, and also comprising a liquid separation plate 64 arranged inside the top cover 23 for detecting the viscosity state of the waste liquid according to the weight and adaptively lifting and lowering, a first scraper 72 and a second scraper 73 arranged on the inner wall of the cylinder 1 for identifying the viscosity state of the waste liquid and adaptively switching between the two states of efficient scraping evaporation and accelerated material discharge, and a switching mechanism for controlling the switching of the first scraper 72 and the second scraper 73 according to the lifting and lowering of the liquid separation plate 64;

[0031] The top surface of the liquid separation plate 64 is configured as an arc surface that is inclined downward from the center to the outside, and the curvature of the end surfaces of the first scraper 72 and the second scraper 73 matches the curvature of the inner wall of the cylinder 1 .

[0032] A heat source inlet 21 is provided at the upper end of the heating cylinder cover 2, and a heat source outlet 22 is provided at the lower end of the heating cylinder cover 2. A liquid inlet 24 is provided at the top center of the top cover 23, and a steam outlet 25 is provided at the top of the top cover 23 on one side of the liquid inlet 24. A concentrated liquid outlet 27 is provided on the outer side of the bottom of the bottom cover 26.

[0033] A shell 3 is fixed at the inner center of the bottom cover 26, and the top of the shell 3 is rotatably connected to a rotating column 4 extending to the inside of the top cover 23. The bottom end of the bottom cover 26 is located inside the shell 3 and a motor 5 is installed, and the output end of the motor 5 is fixed to the bottom end of the rotating column 4.

[0034] The rotating column 4 is set as a hollow structure, and the inner wall of the bottom end of the rotating column 4 is fixedly connected with a first spring 6, the top of the first spring 6 is fixedly connected with a sliding plate 61 that slides with the inner wall of the rotating column 4, a telescopic rod 62 is connected between the sliding plate 61 and the bottom end of the rotating column 4, the upper surface of the sliding plate 61 is fixedly connected with a fixed column 63, the top end of the fixed column 63 is fixedly connected to the bottom end of the liquid separation plate 64, the outer wall of the liquid separation plate 64 is fixed with a limiting column, and the inner wall of the top cover 23 is vertically provided with a limiting groove that slides with the limiting column.

[0035] The outer wall of the cylinder 1 is evenly distributed with fixed plates 7, and two groups of movable rods 71 ​​that slide in cooperation with the fixed plates 7 are symmetrically arranged on the fixed plates 7 toward the inner wall of the cylinder 1, and one end of the two groups of movable rods 71 ​​are respectively fixed to the outer walls of the first scraper 72 and the second scraper 73, and the inclination angles of the first scraper 72 and the second scraper 73 are symmetrically arranged with respect to the center line of the cylinder 1, and a switching mechanism extending to the inside of the rotating column 4 is arranged inside each group of fixed plates 7, and the rotation trajectories of the first scraper 72 and the second scraper 73 on the outer sides of two longitudinally adjacent groups of fixed plates 7 overlap.

[0036] The switching mechanism includes a movable block 74 arranged inside the fixed plate 7, a fixed rod 75 is fixedly arranged inside the movable block 74, a connecting rod 76 is arranged between a group of movable rods 71 ​​and one end of the fixed rod 75, the connecting rod 76 is rotatably connected to the inner wall of the fixed plate 7 through a rotating shaft, the other end of the fixed rod 75 extends to the outer wall of another group of movable rods 71 ​​and is fixed, and sliding grooves 77 are respectively provided at both ends of the connecting rod 76, and sliding buckles 78 that slide with the sliding grooves 77 are respectively provided on the outer wall of a group of movable rods 71 ​​and one end of the fixed rod 75.

[0037] The switching mechanism also includes a connecting column 79 fixedly connected to the outer wall of the movable block 74, the end of the connecting column 79 passes through the interior of the rotating column 4, and a ball is provided at the end of the connecting column 79, a second spring 710 is fixedly connected between the movable block 74 and the rotating column 4, and a columnar block 8 fixed to the outer wall of the fixed column 63 is correspondingly provided on one side of the connecting column 79, and the outer wall of the columnar block 8 is provided with an inner groove 81 that slides with the connecting column 79.

[0038] The inner groove 81 includes a first groove opened vertically and a second groove opened toward the center of the columnar block 8 , and the surface connecting the second groove and the first groove is set as an inclined surface. A limiting ring 82 fixed to the inner wall of the rotating column 4 is set below the columnar block 8 .

[0039] Working principle: When using the scraped film evaporator, the heating source will enter the heating cylinder cover 2 through the heat source inlet 21, and then be discharged through the heat source outlet 22 for circulation, thereby heating the cylinder 1, heating its inner wall to the temperature of evaporating the waste liquid, and the waste liquid is discharged into the top cover 23 through the liquid inlet 24. After the waste liquid is scraped, the evaporated steam will flow upward and be discharged through the steam outlet 25 for condensation and other processing, and the non-evaporable substances will fall to the bottom cover 26 and be discharged and collected through the concentrate outlet 27.

[0040] When there is less viscous matter in the waste liquid and the waste liquid has high fluidity, the waste liquid will fall to the top center of the liquid separation plate 64 and then spread outward, and then flow downward to the inner wall of the cylinder 1. Since the waste liquid will flow along the curved surface on the liquid separation plate 64, the weight of the liquid separation plate 64 is less than the elastic force of the first spring 6. At this time, the elastic force of the first spring 6 limits the sliding of the sliding plate 61, and the waste liquid will not press the liquid separation plate 64 to move downward. Figure 4 As shown, at this time, the end surface of the first scraper 72 does not contact the inner wall of the cylinder 1, and the end surface of the second scraper 73 contacts the inner wall of the cylinder 1. Figure 2 As shown, the motor 5 drives the rotating column 4 to rotate clockwise, and the rotating column 4 drives multiple groups of second scrapers 73 to rotate clockwise. Since the second scrapers 73 are inclined and the rotation ranges of the second scrapers 73 adjacent to each other in the longitudinal direction overlap, when the second scrapers 73 scrape the waste liquid to form a film, after the waste liquid flows downward along the inner wall of the cylinder 1, the second scrapers 73 from top to bottom will produce an upward pushing effect, which can slow down the downward flow speed of the waste liquid when it flows downward, thereby further improving the scraping film evaporation effect of the waste liquid.

[0041] When the rotating column 4 rotates, under the limiting action of the telescopic rod 62, the sliding plate 61 will rotate accordingly, and the sliding plate 61 will drive the fixed column 63 to rotate at the bottom of the liquid separation plate 64, and the liquid separation plate 64 is limited by sliding in the limiting groove on the inner wall of the top cover 23 through the limiting column on the outer wall, and will not rotate.

[0042] When the viscous substances in the waste liquid increase, the components with high fluidity in the waste liquid continue to flow along the curved surface on the liquid separation plate 64, among which the viscous substances with poor fluidity flow slowly on the liquid separation plate 64, and this part of the viscous substances will increase the weight of the liquid separation plate 64, and the liquid separation plate 64 drives the sliding plate 61 to slide downward and squeeze the first spring 6 through the fixed column 63, and the fixed column 63 will drive the columnar block 8 of the outer wall to move downward, and the connecting column 79 slides in the inner groove 81 formed by the first groove and the second groove. During the sliding process of the connecting column 79 in the first groove, it indicates that the content of viscous substances in the waste liquid is not high, and the second scraper 73 can be used for scraping film evaporation, and the second spring 710 is in an elongated state, and the elastic force of the second spring 710 is less than the elastic force of the first spring 6. When the connecting column 79 slides to the second groove, it indicates that the content of viscous substances in the waste liquid is high, and the connecting column 79 slides inward on the rotating column 4 under the action of the second spring 710, and the connecting column 79 slides inward on the rotating column 4. The locking cam 77 is pressed against the locking cam 78 to lock the locking cam 76, and the locking cam 78 is pressed against the support cam 76 to lock the locking cam 76.

[0043] When the viscous matter in the waste liquid decreases to a certain range, the weight of the liquid separation plate 64 will decrease, and the first spring 6 will reset, pushing the sliding plate 61 to reset and pushing the fixed column 63 to reset. Since the surface connecting the second groove and the first groove is set as an inclined surface, the connecting column 79 can be pushed to reset. Similarly, under the action of the switching mechanism, the first scraper 72 and the second scraper 73 are switched and reset.

[0044] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A scraped-wall thin-film evaporator, comprising a cylinder (1), a heating cylinder cover (2) arranged on the outer wall of the cylinder (1), a top cover (23) arranged at the top end of the cylinder (1), and a bottom cover (26) arranged at the bottom end of the cylinder (1), characterized in that: It also includes a liquid separation plate (64) arranged inside the top cover (23) for detecting the viscosity of the waste liquid according to its weight and adaptively raising and lowering it, a first scraper (72) and a second scraper (73) arranged on the inner wall of the cylinder (1) for identifying the viscosity of the waste liquid and adaptively switching between the two states of efficient scraping evaporation and accelerated material discharge, and a switching mechanism for controlling the switching of the first scraper (72) and the second scraper (73) according to the raising and lowering of the liquid separation plate (64); In the high-efficiency scraping evaporation state, when the second scraper (73) scrapes the waste liquid to form a film, after the waste liquid flows downward along the inner wall of the cylinder (1), the second scraper (73) from top to bottom will produce an upward pushing effect, thereby slowing down the downward flow speed of the waste liquid, further improving the scraping film evaporation effect of the waste liquid; The accelerated material discharge state is that the first scraper (72) rotates clockwise to produce a downward scraping effect, thereby improving the discharge efficiency of viscous substances and reducing the influence of substances adhering to the inner wall of the cylinder (1) on the scraping film; The outer wall of the cylinder (1) is evenly distributed with fixed plates (7), and the fixed plates (7) are symmetrically provided with two groups of movable rods (71) that are slidably matched with the fixed plates (7) in the direction facing the inner wall of the cylinder (1), one end of the two groups of movable rods (71) are respectively fixed to the outer walls of the first scraper (72) and the second scraper (73), and the inclination angles of the first scraper (72) and the second scraper (73) are symmetrically arranged with respect to the center line of the cylinder (1), and a switching mechanism extending to the inside of the rotating column (4) is arranged inside each group of the fixed plates (7), and the rotational tracks of the first scraper (72) and the second scraper (73) on the outer sides of two longitudinally adjacent groups of the fixed plates (7) overlap; The top surface of the liquid separation plate (64) is configured as a curved surface that slopes downward from the center to the outside, and the curvature of the end surfaces of the first scraper (72) and the second scraper (73) matches the curvature of the inner wall of the cylinder (1).

2. A scraped thin film evaporator according to claim 1, characterized in that: The upper end of the heating cylinder cover (2) is provided with a heat source inlet (21), and the lower end of the heating cylinder cover (2) is provided with a heat source outlet (22); a liquid inlet (24) is provided at the center of the top of the top cover (23), and a steam outlet (25) is provided at the top of the top cover (23) on one side of the liquid inlet (24); and a concentrated liquid outlet (27) is provided at the outer side of the bottom of the bottom cover (26).

3. A scraped thin film evaporator according to claim 2, characterized in that: A housing (3) is fixed at the inner center of the bottom cover (26); the top of the housing (3) is rotatably connected to a rotating column (4) extending into the interior of the top cover (23); a motor (5) is installed at the bottom end of the bottom cover (26) located inside the housing (3); and the output end of the motor (5) is fixed to the bottom end of the rotating column (4).

4. A scraped thin film evaporator according to claim 3, characterized in that: The rotating column (4) is configured as a hollow structure, and a first spring (6) is fixedly connected to the inner wall of the bottom end of the rotating column (4), a sliding plate (61) slidably matched with the inner wall of the rotating column (4) is fixedly connected to the top of the first spring (6), a telescopic rod (62) is connected between the sliding plate (61) and the bottom end of the rotating column (4), a fixed column (63) is fixedly connected to the upper surface of the sliding plate (61), the top end of the fixed column (63) is fixedly connected to the bottom end of the liquid separation plate (64), a limiting column is fixed to the outer wall of the liquid separation plate (64), and a limiting groove slidably matched with the limiting column is vertically opened on the inner wall of the top cover (23).

5. A scraped thin film evaporator according to claim 1, characterized in that: The switching mechanism comprises a movable block (74) arranged inside a fixed plate (7), a fixed rod (75) being fixedly arranged inside the movable block (74), a connecting rod (76) being arranged between one end of a group of movable rods (71) and the fixed rod (75), the connecting rod (76) being rotatably connected to the inner wall of the fixed plate (7) via a rotating shaft, the other end of the fixed rod (75) extending to and being fixed to the outer wall of another group of movable rods (71), two ends of the connecting rod (76) being respectively provided with sliding grooves (77), and the outer wall of one group of movable rods (71) and one end of the fixed rod (75) being respectively provided with sliding buckles (78) slidably matched with the sliding grooves (77).

6. A scraped thin film evaporator according to claim 5, characterized in that: The switching mechanism further comprises a connecting column (79) fixedly connected to the outer wall of the movable block (74), the end of the connecting column (79) extending through the interior of the rotating column (4), and a ball bearing is arranged at the end of the connecting column (79), a second spring (710) is fixedly connected between the movable block (74) and the rotating column (4), and a columnar block (8) fixed to the outer wall of the fixed column (63) is arranged on one side of the connecting column (79), and an inner groove (81) is provided on the outer wall of the columnar block (8) for slidingly matching with the connecting column (79).

7. A scraped thin film evaporator according to claim 6, characterized in that: The inner groove (81) comprises a first groove opened vertically and a second groove opened towards the center of the columnar block (8), and the surface connecting the second groove and the first groove is arranged as an inclined surface. A limiting ring (82) fixed to the inner wall of the rotating column (4) is arranged below the columnar block (8).

Images