CN220738925U

CN220738925U - Cleaning device for three-necked flask in magnetic bead production process

Info

Publication number: CN220738925U
Application number: CN202322236392.9U
Authority: CN
Inventors: 张洁; 刘瑞琼
Original assignee: Luoyang Huiqing Biotechnology Co ltd
Current assignee: Luoyang Huiqing Biotechnology Co ltd
Priority date: 2023-08-18
Filing date: 2023-08-18
Publication date: 2024-04-09
Anticipated expiration: 2033-08-18

Abstract

The utility model relates to the technical field of magnetic bead production, in particular to a cleaning device for a three-neck flask in the magnetic bead production process. Comprises a supporting tube, a cleaning plate, a fulcrum component, a cleaning component and a containing component. Before stretching into the three-necked flask with the clean board, accomodate the subassembly and make clean board concave surface and stay tube convex surface laminating accomodate to the extension of convenient clean board, after clean, accomodate the subassembly and make clean board concave surface and stay tube convex surface laminating accomodate again, when conveniently taking clean board out the three-necked flask, avoid the bottleneck bullet to dial the brush hair and arouse the water droplet to splash, improve the security.

Description

Cleaning device for three-necked flask in magnetic bead production process

Technical Field

The utility model relates to the technical field of magnetic bead production, in particular to a cleaning device for a three-neck flask in the magnetic bead production process.

Background

A three-necked flask is a common laboratory apparatus used in chemical laboratories, and in many laboratories, a three-necked flask is provided with a bulb at the bottom and three elongated necks at the upper end. In the case of cleaning a three-necked flask, an elongated cleaning brush may be used to extend into the bottom of the three-necked flask for cleaning. However, due to the special structure of the three-necked flask, the common brush is difficult to find the acting point and the cleaning process is difficult to operate, and intractable stains generated on the inner wall of the three-necked flask in the magnetic bead production process are difficult to clean, so that the wall of the three-necked flask is stuck with the stains in the whole process, and the observation experimental phenomenon is influenced.

In the prior art, if the publication number is CN218551671U, the name is a Chinese patent for a cleaning brush of a three-neck flask, the technical scheme is disclosed, the spring is in an extension state, when the brush connecting rod enters the interior of the three-neck flask, the brush connecting rod enables the brush hair to be in close contact with the inner wall under the action of the elasticity of the spring, and the cleaning of stubborn stains attached to the inner wall is facilitated. However, when the hairbrush shown in the scheme is used, the elastic force of the spring is overcome firstly to gather the hairbrush body, then the hairbrush is plugged into the flask, a tool cannot enter the flask when the force is too small, and the flask is possibly damaged when the force is too large. And when taking out, because the spring is in the extension state, after the brush body is stained with water in the cleaning process, and need pull out by force under the effect of spring, can cause the water droplet to splash when the brush body is pulled out, if the inside dangerous reagent that is of flask, there is certain security risk.

Disclosure of Invention

The utility model provides a cleaning device for a three-necked flask in the process of producing magnetic beads, which aims to solve the problems.

The utility model adopts the following technical scheme: a belt cleaning device for three-necked flask in magnetic bead production process, including stay tube, cleaning plate, fulcrum subassembly, cleaning assembly, accomodate the subassembly;

the supporting tube is arranged up and down, the upper end is vertically arranged, and the lower end is arranged in an arc shape and is used for conveniently cleaning the arc-shaped inner wall of the flask;

the cleaning plate is an arc-shaped elastic plate, the convex surface of the cleaning plate faces the inner wall of the flask, and the cleaning plate is rotatably arranged at the lower end of the supporting tube through the rotating assembly; the convex surface of the cleaning plate is provided with brush hair;

the fulcrum component is arranged at the upper end of the supporting tube and is used for providing a fulcrum for the supporting tube when the supporting tube is inclined to the inner wall of the three-neck flask to clean stubborn stains generated on the inner wall of the three-neck flask in the production process of brushing the magnetic beads, so that labor is saved when the three-neck flask is cleaned;

the cleaning component is used for timely flushing the inner wall of the flask after the brush hair is cleaned so as to observe the cleaning progress;

the storage component is arranged between the support tube and the cleaning plate and used for enabling the concave surface of the cleaning plate to be attached to the convex surface of the support tube and stored before the cleaning plate stretches into the three-necked flask so as to facilitate the extension of the cleaning plate, and enabling the concave surface of the cleaning plate to be attached to the convex surface of the support tube and stored again after the cleaning is finished so as to facilitate the extraction of the cleaning plate from the three-necked flask, avoid the splashing of water drops caused by the flicking of bristles from the flask mouth and improve the safety.

Further, the storage component comprises an outer magnetic sheet and an inner magnetic sheet; the outer magnetic sheet is fixed on the convex surface of the support tube, and the inner magnetic sheet is fixed on the inner concave surface of the self-cleaning plate. When in use, the outer magnetic sheet and the inner magnetic sheet are sucked together, so that the outer magnetic sheet and the inner magnetic sheet are conveniently taken out and put into the flask.

Further, the fulcrum assembly comprises a slip ring and a fixed ring; the slip ring is sleeved on the outer side of the support tube in a sliding manner; the outer side wall of the slip ring is in a convex arc shape; the fixed ring is a rubber ring and is sleeved on the outer side of the slip ring; the outer diameter of the fixed ring is matched with the inner diameter of the bottle mouth of the three-neck flask; a matching ring is arranged between the fixed ring and the slip ring; the matching ring is fixedly connected with the fixed ring through a connecting rod; the inner side wall of the matching ring, which is close to the slip ring, is in a recessed arc shape; the matching ring is matched with the slip ring through a spherical hinge. When the three-necked flask is used, the fixing ring is inserted into the opening of the three-necked flask, the supporting tube is pulled by hand to enable the supporting tube and the slip ring to slide relatively, and the cleaning position of the cleaning plate on the inner wall of the three-necked flask is adjusted. The upper end of the supporting tube is pressed by hands, so that the supporting tube takes the matching ring as a fulcrum to form a lever structure, and labor is saved when the three-necked flask is cleaned.

Further, the cleaning component comprises a pressurizing bag and a water spraying cavity; the water spraying cavity is arranged in the cleaning plate and is communicated with the supporting pipe through a hose; the wall of the water spraying cavity, which is close to the brush hair, is provided with water spraying holes; the water spraying hole is used for communicating the water spraying cavity with the outside; the pressurizing bag is an elastic rubber bag; the pressurizing bag is provided with a water inlet and a water outlet; the water outlet of the pressurizing bag is fixed at the upper end of the supporting tube; the pressurizing bag is communicated with the supporting tube; a one-way valve is arranged in the water inlet of the pressurizing bag; the one-way valve prevents water in the pressurizing bag from flowing out of the water inlet. When water spraying cleaning is needed, water is injected into the water spraying cavity through the support pipe through the water inlet of the pressurizing bag, and the water is sprayed to the inner wall of the flask from the water spraying hole. When encountering more intractable stains, the pressurizing bag is extruded, the water pressure sprayed from the water spraying holes is improved, and the bristles are assisted to clean the stains.

Further, a handle is fixed at the upper end of the supporting tube; the handle is provided with a push button; the button is arranged on the handle in a radial sliding way along the handle; a blocking spring is connected between the button and the handle; the button is provided with a water through level and a water sealing level; the water through hole is arranged at the water through level; the water through hole is far away from the axis of the support tube; a blocking block is arranged at the water sealing level; the plugging block is arranged close to the axis of the support tube. When water spraying is needed, the button is pressed, the blocking spring is compressed, the water through hole corresponds to the support tube, and the support tube is enabled to be filled with water.

Further, the rotating assembly comprises a rotating seat and a rotating block; the rotating seat comprises two elastic clamping plates which are symmetrically arranged; the clamping plate is fixed on the concave surface of the cleaning plate; the rotating block is arranged between the two clamping plates; the rotating block is fixed at the lower end of the supporting tube; the rotating shaft is inserted in the middle parts of the rotating block and the clamping plate; the rotating shaft is in rotating fit with the rotating block; one end of the rotating shaft is in threaded fit with the corresponding clamping plate, and the other end of the rotating shaft is fixed with a stop block; the stop block is matched with the corresponding clamping plate in a stop way. When the flexibility of the rotation of the cleaning plate needs to be adjusted, the rotating shaft is twisted, and the distance between the two clamping plates is adjusted so as to adjust the extrusion force between the clamping plates and the rotating block.

Further, the outer side wall of the fixing ring is conical with the small end arranged downwards. So as to adapt to three-neck flasks of different specifications.

The beneficial effects of the utility model are as follows: before stretching into the three-necked flask with the clean board, accomodate the subassembly and make clean board concave surface and stay tube convex surface laminating accomodate to the extension of convenient clean board, after clean, accomodate the subassembly and make clean board concave surface and stay tube convex surface laminating accomodate again, when conveniently taking clean board out the three-necked flask, avoid the bottleneck bullet to dial the brush hair and arouse the water droplet to splash, improve the security.

Further, the fixing ring is inserted into the bottle mouth of the three-necked flask, the supporting tube is pulled by hand to enable the supporting tube and the slip ring to slide relatively, and the cleaning position of the cleaning plate on the inner wall of the three-necked flask is adjusted. The upper end of the supporting tube is pressed by hands, so that the supporting tube takes the matching ring as a fulcrum to form a lever structure, and labor is saved when the three-necked flask is cleaned.

Drawings

In order to more clearly illustrate the embodiments of the utility model or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the utility model, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.

FIG. 1 is a schematic view showing the structure of an example of a cleaning apparatus for a three-necked flask in the process of producing magnetic beads according to the present utility model;

FIG. 2 is a cross-sectional view of an embodiment of the present utility model;

FIG. 3 is an enlarged view of FIG. 2 at A;

FIG. 4 is an enlarged view at B in FIG. 2;

FIG. 5 is an enlarged view at C in FIG. 2;

FIG. 6 is a schematic diagram of an embodiment of the present utility model when used in a three-necked flask.

In the figure: 100. a support tube; 110. a handle; 120. a button; 200. a cleaning plate; 300. a fulcrum assembly; 310. a slip ring; 320. a fixing ring; 330. a mating ring; 400. cleaning the assembly; 410. a pressurizing bag; 420. a water spray cavity; 430. a one-way valve; 500. a receiving assembly; 510. an outer magnetic sheet; 520. an inner magnetic sheet; 600. a rotating assembly; 610. a rotating shaft; 620. and (3) clamping plates.

Detailed Description

Reference will now be made in detail to the present embodiments of the present utility model, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the like or similar elements throughout or elements having the same or similar functions. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The features of the utility model "first", "second" and the like in the description and in the claims may be used for the explicit or implicit inclusion of one or more such features. In the description of the present utility model, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present utility model, it should be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

An embodiment of a cleaning device for a three-necked flask in a magnetic bead production process according to the present utility model is shown in fig. 1 to 6: a cleaning device for a three-necked flask in a magnetic bead production process comprises a supporting tube 100, a cleaning plate 200, a fulcrum assembly 300, a cleaning assembly 400 and a containing assembly 500. The support tube 100 is disposed up and down, with its upper end disposed vertically and its lower end disposed in a circular arc shape, for convenient cleaning of the circular arc-shaped inner wall of the flask.

The cleaning plate 200 is an arc-shaped elastic plate, and the convex surface of the cleaning plate 200 is disposed toward the inner wall of the flask and rotatably installed at the lower end of the support tube 100 by the rotation assembly 600. The rotating assembly 600 includes a rotating seat and a rotating block. The swivel mount comprises two symmetrically arranged resilient clamping plates 620. The clamping plate 620 is fixed to the concave surface of the cleaning plate 200. The rotating block is provided between the two clamping plates 620. The rotating block is fixed at the lower end of the support pipe 100. The rotation shaft 610 is inserted in the middle of the rotation block and the clamping plate 620. The rotation shaft 610 is rotatably fitted to the rotation block. One end of the rotating shaft 610 is in threaded fit with a corresponding clamping plate 620, and the other end is fixed with a stop block. The stop is in a stop fit with the corresponding clamp plate 620. When it is required to adjust the rotational flexibility of the cleaning plate 200, the rotation shaft 610 is twisted to adjust the interval between the clamping plates 620, so as to adjust the pressing force between the clamping plates 620 and the rotating block. Bristles are provided on the convex surface of the cleaning plate 200.

The fulcrum assembly 300 is provided at the upper end of the support tube 100, and the fulcrum assembly 300 includes a slip ring 310, a fixed ring 320. Slip ring 310 is slidably sleeved outside support tube 100. The outer side wall of the slip ring 310 is convex arc-shaped. The fixing ring 320 is a rubber ring and is sleeved outside the slip ring 310. The outer diameter of the fixing ring 320 is matched with the inner diameter of the bottle mouth of the three-neck flask. The outer side wall of the fixing ring 320 is cone-shaped with the small end facing downwards. So as to adapt to three-neck flasks of different specifications. A mating ring 330 is provided between the stationary ring 320 and the slip ring 310. The mating ring 330 and the securing ring 320 are fixedly coupled by a connecting rod. The inner side wall of the mating ring 330 adjacent to the slip ring 310 is recessed in a circular arc shape. The engagement ring 330 is ball-hinged to the slip ring 310. When the stay tube 100 is inclined to brush stubborn stains generated on the inner wall of the three-necked flask in the production process of the magnetic beads, the fixing ring 320 is inserted into the bottleneck of the three-necked flask, and the stay tube 100 is manually drawn to enable the stay tube 100 and the slip ring 310 to slide relatively, so that the cleaning position of the inner wall of the three-necked flask is adjusted by the cleaning plate 200. The upper end of the support tube 100 is pressed by hand so that the support tube 100 forms a lever structure with the fitting ring 330 as a fulcrum, thereby saving labor when cleaning the three-necked flask.

The cleaning assembly 400 includes a pressurized bladder 410, a water spray chamber 420. The water spray chamber 420 is provided in the cleaning plate 200 and communicates with the support pipe 100 through a hose. The wall of the water spraying cavity 420, which is close to the brush hair, is provided with water spraying holes. The water spraying hole communicates the water spraying chamber 420 with the outside. The pressurizing bladder 410 is an elastic rubber bladder. The pressurizing bag 410 is provided with a water inlet and a water outlet. The water outlet of the pressurizing bag 410 is fixed at the upper end of the support tube 100. The plenum 410 communicates with the support tube 100. A one-way valve 430 is provided in the inlet of the pressurizing bag 410. The check valve 430 prevents water in the pressurizing bladder 410 from flowing out of the water inlet. When water spraying cleaning is needed, water is injected into the water spraying cavity 420 through the water inlet of the pressurizing bag 410 and through the supporting pipe 100, and the water is sprayed to the inner wall of the flask from the water spraying hole. When encountering more stubborn stains, the pressurizing bag 410 is extruded, the water pressure sprayed from the water spraying hole is increased, the bristles are assisted to clean the stains, and the inner wall of the flask after the bristles are cleaned is washed in time so as to observe the cleaning progress.

The receiving assembly 500 is provided between the support pipe 100 and the cleaning plate 200, and the receiving assembly 500 includes an outer magnetic sheet 510 and an inner magnetic sheet 520. The outer magnetic sheet 510 is fixed to the convex surface of the support pipe 100, and the inner magnetic sheet 520 is fixed to the concave surface of the self-cleaning plate 200. When the three-necked flask is used, the outer magnetic sheet 510 and the inner magnetic sheet 520 are sucked together to be convenient to take out and put into the flask, so that before the cleaning plate 200 is stretched into the three-necked flask, the concave surface of the cleaning plate 200 and the convex surface of the supporting tube 100 are attached and stored, the cleaning plate 200 is conveniently stretched into the flask, after the cleaning is finished, the concave surface of the cleaning plate 200 and the convex surface of the supporting tube 100 are attached and stored again, and when the cleaning plate 200 is conveniently pulled out of the three-necked flask, water drops are prevented from splashing due to the fact that bristles are flicked by a flask mouth, and safety is improved.

In this embodiment, a handle 110 is fixed to the upper end of the support tube 100. The handle 110 is provided with a push button 120. The button 120 is slidably provided on the handle 110 in a radial direction of the handle 110. A blocking spring is connected between the button 120 and the handle 110. The button 120 is provided with a water passing level and a water sealing level. The water through level is provided with a water through hole. The water passage holes are disposed away from the axis of the support tube 100. The water sealing level is provided with a blocking block. The block is disposed adjacent to the axis of the support tube 100. When water spraying is required, the button 120 is pressed, and the blocking spring is compressed, so that the water through holes correspond to the support tube 100, and the support tube 100 is enabled to be filled with water.

In combination with the above embodiment, the use principle and working process of the present utility model are as follows: when the supporting tube 100 is inclined to brush stubborn stains generated on the inner wall of the three-necked flask in the production process of the magnetic beads, the outer magnetic sheet 510 and the inner magnetic sheet 520 are firstly sucked together to be convenient to take out and put into the flask, so that the concave surface of the cleaning plate 200 and the convex surface of the supporting tube 100 are attached and stored before the cleaning plate 200 is stretched into the three-necked flask to facilitate the stretching of the cleaning plate 200, then the fixing ring 320 is inserted into the bottle mouth of the three-necked flask, and the supporting tube 100 is drawn by hands to enable the supporting tube 100 and the sliding ring 310 to slide relatively, so that the cleaning position of the inner wall of the three-necked flask by the cleaning plate 200 is adjusted. The upper end of the support tube 100 is pressed by hand so that the support tube 100 forms a lever structure with the fitting ring 330 as a fulcrum, thereby saving labor when cleaning the three-necked flask.

When water spraying is required, the button 120 is pressed, and the blocking spring is compressed, so that the water through holes correspond to the support tube 100, and the support tube 100 is enabled to be filled with water. The water injection cavity 420 is filled with water through the support tube 100 via the water inlet of the pressurizing bag 410, and the water is sprayed to the inner wall of the flask from the water spray hole. When encountering more stubborn stains, the pressurizing bag 410 is extruded, the water pressure sprayed from the water spraying hole is increased, the bristles are assisted to clean the stains, and the inner wall of the flask after the bristles are cleaned is washed in time so as to observe the cleaning progress.

After cleaning, the concave surface of the cleaning plate 200 and the convex surface of the supporting tube 100 are attached and stored again, so that when the cleaning plate 200 is pulled out of the three-neck flask, water drops are prevented from splashing caused by the fact that bristles are flicked from the flask mouth, and safety is improved.

The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.

Claims

1. A belt cleaning device that is arranged in magnetic bead production process three-necked flask, its characterized in that: comprises a supporting tube (100), a cleaning plate (200), a fulcrum component (300), a cleaning component (400) and a containing component (500);

the supporting tube (100) is arranged up and down, the upper end is arranged vertically, and the lower end is arranged in an arc shape;

the cleaning plate (200) is an arc-shaped elastic plate, the convex surface of the cleaning plate (200) faces the inner wall of the flask, and the cleaning plate is rotatably arranged at the lower end of the supporting tube (100) through the rotating assembly (600); the convex surface of the cleaning plate (200) is provided with brush hair;

the fulcrum component (300) is arranged at the upper end of the supporting tube (100) and is used for providing a lever fulcrum for the supporting tube (100) when the supporting tube (100) is inclined to brush stubborn stains generated on the inner wall of the three-necked flask in the process of producing the magnetic beads;

the cleaning component (400) is used for timely flushing the inner wall of the flask after the brush hair is cleaned so as to observe the cleaning progress;

the storage assembly (500) is arranged between the support tube (100) and the cleaning plate (200) and is used for enabling the concave surface of the cleaning plate (200) to be attached to and stored in the convex surface of the support tube (100) before the cleaning plate (200) is stretched into the three-necked flask, and enabling the concave surface of the cleaning plate (200) to be attached to and stored in the convex surface of the support tube (100) after cleaning is finished.

2. The cleaning device for a three-necked flask in a magnetic bead manufacturing process according to claim 1, wherein: the storage component (500) comprises an outer magnetic sheet (510) and an inner magnetic sheet (520); the outer magnetic sheet (510) is fixed on the convex surface of the support tube (100), and the inner magnetic sheet (520) is fixed on the inner concave surface of the self-cleaning plate (200).

3. The cleaning device for a three-necked flask in a magnetic bead production process according to claim 2, wherein: the fulcrum component (300) comprises a slip ring (310) and a fixed ring (320); the slip ring (310) is sleeved on the outer side of the support tube (100) in a sliding manner; the outer side wall of the slip ring (310) is in a convex arc shape; the fixed ring (320) is a rubber ring and is sleeved on the outer side of the slip ring (310); the outer diameter of the fixed ring (320) is matched with the inner diameter of the bottle mouth of the three-neck flask; a matching ring (330) is arranged between the fixed ring (320) and the slip ring (310); the matching ring (330) and the fixed ring (320) are fixedly connected through a connecting rod; the inner side wall of the matching ring (330) is concave arc-shaped; the matching ring (330) and the slip ring (310) are in spherical hinge matching.

4. The cleaning device for a three-necked flask in a magnetic bead manufacturing process according to claim 1, wherein: the cleaning assembly (400) comprises a pressurizing bag (410) and a water spraying cavity (420); the water spraying cavity (420) is arranged in the cleaning plate (200) and is communicated with the supporting tube (100) through a hose; the wall of the water spraying cavity (420) close to the brush hair is provided with water spraying holes; the water spraying hole communicates the water spraying cavity (420) with the outside; the pressurizing bag (410) is an elastic rubber bag; the pressurizing bag (410) is provided with a water inlet and a water outlet; the water outlet of the pressurizing bag (410) is fixed at the upper end of the supporting tube (100); the pressurizing bag (410) is communicated with the supporting tube (100); a one-way valve (430) is arranged in the water inlet of the pressurizing bag (410); the one-way valve (430) prevents water in the pressurizing bag (410) from flowing out of the water inlet.

5. The cleaning device for a three-necked flask in a magnetic bead manufacturing process of claim 4, wherein: a handle (110) is fixed at the upper end of the supporting tube (100); the handle (110) is provided with a push button (120); the button (120) is arranged on the handle (110) in a radial sliding way along the handle (110); a blocking spring is connected between the button (120) and the handle (110); the button (120) is provided with a water through level and a water sealing level; the water through hole is arranged at the water through level; the water through hole is far away from the axis of the support tube (100); a blocking block is arranged at the water sealing level; the block is disposed adjacent to the axis of the support tube (100).

6. The cleaning device for a three-necked flask in a magnetic bead manufacturing process according to claim 1, wherein: the rotating assembly (600) comprises a rotating seat and a rotating block; the rotating seat comprises two symmetrically arranged elastic clamping plates (620); the clamping plate (620) is fixed on the concave surface of the cleaning plate (200); the rotating block is arranged between the two clamping plates (620); the rotating block is fixed at the lower end of the supporting tube (100); the rotating shaft (610) is inserted in the middle parts of the rotating block and the clamping plate (620); the rotating shaft (610) is in rotating fit with the rotating block; one end of the rotating shaft (610) is in threaded fit with a corresponding clamping plate (620), and a stop block is fixed at the other end of the rotating shaft; the stop is in stop fit with a corresponding cleat (620).

7. A cleaning device for a three-necked flask in a magnetic bead manufacturing process as defined in claim 3, wherein: the outer side wall of the fixed ring (320) is cone-shaped with the small end arranged downwards.