Screw propulsion type toothpaste tube
By introducing the spiral propulsion mechanism in the toothpaste tube, the coordination of rotating seats, driving screws and pistons is used to solve the problem of residue in the inner wall of the toothpaste tube, and the effective launch and use of toothpaste are achieved.
Patent Information
- Application Number
- CN202421097501.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2023-05-29
- Filing Date
- 2024-05-20
- Publication Date
- 2025-01-28
- Estimated Expiration
- 2034-05-20
AI Technical Summary
It is difficult to clean the remaining toothpaste on the inner wall during use, resulting in waste of toothpaste and inconvenient use.
A spiral pushing toothpaste tube is designed. By setting the rotating rotating seats and driving screws at the opening of the tube, driving the piston to slide along the axis under the guidance of the guide structure, thereby gradually launching the toothpaste.
Effectively reduce the residue of toothpaste in the toothpaste, improve the convenience of use, reduce the waste of toothpaste, and provide a better experience.
Smart Images

Figure CN222409267U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of toothpaste tubes, in particular to a spiral-propelled toothpaste tube. Background Art
[0002] As we all know, toothpaste tubes are packaging tubes used to store toothpaste fluid products. Toothpaste is an indispensable tooth cleaning product in our daily life. Toothpaste is generally stored in toothpaste tubes. A good quality toothpaste tube should be able to naturally squeeze out a relatively delicate and smooth paste, and be in a normal round strip shape.
[0003] Existing toothpaste tubes are generally soft packaging shells. When in use, users squeeze the tube wall of the toothpaste tube through external force, causing the tube to deform, and then the toothpaste inside the tube flows out from the outlet. However, when in use, the toothpaste inside the toothpaste tube cannot be scraped off, so that a large amount of toothpaste is easily left on the inner wall of the toothpaste tube, resulting in a waste of toothpaste, and it is inconvenient to squeeze the toothpaste.
[0004] Therefore, it is necessary to provide a novel toothpaste packaging tube to solve the above-mentioned technical problems. Utility Model Content
[0005] The utility model aims to provide a spiral-propelled toothpaste tube, aiming to solve the technical problem in the prior art that a large amount of toothpaste remains on the inner wall of the toothpaste tube, causing waste.
[0006] In order to achieve the above-mentioned purpose, the technical solution of the utility model provides a spiral propulsion type toothpaste tube, comprising:
[0007] A tube body, one end of which is provided with a discharge port, the other end of which is open, and the cross-sectional shape of the tube body is a perfect circle;
[0008] A rotating seat, the rotating seat is rotatably covered on the opening of the tube body;
[0009] A driving screw rod, the driving screw rod extending along the axial direction of the tube body and disposed in the tube body, and one end of the driving screw rod is connected to the inner end wall of the rotating seat;
[0010] A piston, the piston is movably disposed in the tube body, and the piston is provided with a threaded hole in the axial direction, so that the piston can be sleeved on the driving screw through the threaded hole;
[0011] A guide structure is provided between the outer peripheral surface of the piston and the inner wall of the tube body, so as to guide the piston to move axially in the tube body through the guide structure.
[0012] Furthermore, the guide structure includes a raised rib and a strip groove, one of the raised rib and the strip groove is arranged on the inner wall of the tube body, and the other of the raised rib and the strip groove is arranged on the outer peripheral surface of the piston, the raised rib can be slidably embedded in the strip groove, and the raised rib and the strip groove are both extended along the axial direction of the tube body.
[0013] Furthermore, the tube body includes an inner tube and an outer tube which are detachably mounted on each other, one end of the outer tube is provided with an opening, and the other end thereof is open, one end of the inner tube is provided with a discharge pipe opening, and the other end thereof is open, so that the discharge pipe opening passes through the opening to be exposed to form the discharge port, and a structure which can slide axially but cannot rotate relative to each other is provided between the opening and the discharge pipe opening.
[0014] Furthermore, a connecting cylinder is provided at the center of the inner wall of the rotating seat, one end of the driving screw is installed in the connecting cylinder, and a structure that can be axially plugged and assembled but cannot rotate relative to each other is provided between the connecting cylinder and one end of the driving screw.
[0015] Furthermore, a first limiting convex ring is circumferentially provided on the inner side wall of the rotating seat, and a second limiting convex ring is circumferentially provided on the outer circumferential surface of the tube body, and the second limiting convex ring is located on the inner side of the first limiting convex ring.
[0016] In addition, the technical solution of the utility model provides a spiral propulsion type toothpaste tube, comprising:
[0017] A tube body, one end of which is provided with a discharge port, the other end of which is open, and the inner surface cross-section of the tube body is polygonal or elliptical;
[0018] A rotating seat, the rotating seat is rotatably covered on the opening of the tube body;
[0019] A driving screw rod, the driving screw rod extending along the axial direction of the tube body and disposed in the tube body, and one end of the driving screw rod is connected to the inner end wall of the rotating seat;
[0020] The piston is movably arranged in the tube body, the cross-sectional shape of the piston is matched with the cross-sectional shape of the inner surface of the tube body, and the piston is axially penetrated with a threaded hole so that the piston can be sleeved on the driving screw through the threaded hole.
[0021] Furthermore, the tube body includes an inner tube and an outer tube which are detachably mounted on each other, one end of the outer tube is provided with an opening, and the other end thereof is open, one end of the inner tube is provided with a discharge pipe opening, and the other end thereof is open, so that the discharge pipe opening passes through the opening to be exposed to form the discharge port, and a structure which can slide axially but cannot rotate relative to each other is provided between the opening and the discharge pipe opening.
[0022] Furthermore, a connecting cylinder is provided at the center of the inner wall of the rotating seat, one end of the driving screw is installed in the connecting cylinder, and a structure that can be axially plugged and assembled but cannot rotate relative to each other is provided between the connecting cylinder and one end of the driving screw.
[0023] Furthermore, a first limiting convex ring is circumferentially provided on the inner side wall of the rotating seat, and a second limiting convex ring is circumferentially provided on the outer circumferential surface of the tube body, and the second limiting convex ring is located on the inner side of the first limiting convex ring.
[0024] It can be seen from the above technical scheme that the spiral-propelled toothpaste tube of the utility model is rotatably provided with a rotating seat at the opening of the tube body. The user can hold the tube body and rotate the rotating seat so that the rotating seat drives the driving screw to rotate together. Since the driving screw cooperates with the piston thread, the piston is driven to slide and advance axially under the guidance of the guide structure by means of spiral force, so that the toothpaste in the tube body is gradually pushed out from its discharge port for daily brushing. It squeezes the toothpaste by setting a piston to push the toothpaste, which can effectively reduce the toothpaste residue in the tube body, facilitates the user's daily squeezing of toothpaste, and thus brings a better user experience.
[0025] In order to make the technical concept and other purposes, advantages, features and functions of the present invention more clearly understood, preferred embodiments will be specifically cited in the following specific implementation manner and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0027] Figure 1 is a three-dimensional diagram of a spiral propulsion toothpaste tube according to an embodiment of the present application;
[0028] Figure 2 This is a front view of a spiral-propelled toothpaste tube according to an embodiment of the present application;
[0029] Figure 3The embodiment of this application provides Figure 2 Sectional view of the middle section AA;
[0030] Figure 4 is a structural exploded view of a spiral-propelled toothpaste tube according to an embodiment of the present application;
[0031] Figure 5 This is a structural breakdown diagram of a spiral propulsion toothpaste tube according to another embodiment of the present application.
[0032] The above drawings include the following reference numerals:
[0033] 100, tube body; 110, inner tube; 111, discharge port; 120, outer tube; 121, opening; 122, second limiting convex ring;
[0034] 200, rotating seat; 210, connecting tube; 220, first limiting convex ring;
[0035] 300, driving screw;
[0036] 400, piston; 410, body; 411, threaded hole; 420, convex head;
[0037] 510. Raised ribs; 520. Strip grooves. DETAILED DESCRIPTION
[0038] The embodiment of the present application provides a spiral propulsion toothpaste tube to solve the technical problem of a large amount of toothpaste remaining on the inner wall of the toothpaste tube in the prior art causing waste. The toothpaste is squeezed by setting a piston 400 to push the toothpaste, so that basically all the toothpaste in the tube body 100 can be pushed out for daily brushing, which can effectively avoid waste caused by toothpaste remaining in the tube body 100. The structural design is ingenious and easy to use.
[0039] In order to enable those skilled in the art to better understand the technical solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.
[0040] Please also read Figures 1 to 5The present embodiment provides a spiral propulsion toothpaste tube, comprising a tube body 100, a rotating seat 200, a driving screw 300, a piston 400 and a guide structure. A discharge port 111 is provided at one end of the tube body 100, and the other end of the tube body 100 is open. The rotating seat 200 is rotatably covered at the opening of the tube body 100. The driving screw 300 is extended along the axial direction of the tube body 100 and is arranged in the tube body 100, and one end of the driving screw 300 is connected to the inner end wall of the rotating seat 200. The piston 400 is movably arranged in the tube body 100, and the piston 400 is sleeved on the driving screw 300 by a threaded connection. The guide structure is arranged between the outer circumferential surface of the piston 400 and the inner wall of the tube body 100, so as to guide the piston 400 to move axially in the tube body 100 through the guide structure, so that the piston 400 pushes the toothpaste in the tube body 100 out from the discharge port 111 for brushing teeth.
[0041] It can be seen that the spiral-propelled toothpaste tube of this embodiment is rotatably provided with a rotating seat 200 at the opening of the tube body 100. The user can hold the tube body 100 and rotate the rotating seat 200 so that the rotating seat 200 drives the driving screw 300 to rotate together. Since the driving screw 300 is threadedly matched with the piston 400, the piston 400 is driven to slide and advance axially under the guidance of the guide structure by means of the spiral force, so that the toothpaste in the tube body 100 is gradually pushed out from its discharge port 111 for daily brushing of teeth. The toothpaste is squeezed by setting the piston 400 to push, which can effectively reduce the toothpaste residue in the tube body 100, facilitate the user's daily squeezing of toothpaste, and thus bring a better user experience.
[0042] In one embodiment, if Figure 4 As shown, the cross-sectional shape of the tube body 100 is a perfect circle, and the guide structure includes a raised rib 510 and a strip groove 520. One of the raised rib 510 and the strip groove 520 is arranged on the inner wall of the tube body 100, and the other of the raised rib 510 and the strip groove 520 is arranged on the outer peripheral surface of the piston 400. The raised rib 510 can be slidably embedded in the strip groove 520, and the raised rib 510 and the strip groove 520 are both extended along the axial direction of the tube body 100. In this way, the raised rib 510 and the strip groove 520 are axially slidably matched to limit the piston 400 and the tube body 100 from relative rotation.
[0043] In another embodiment, Figure 5As shown, the cross-sectional shape of the inner surface of the tube body 100 is matched with the cross-sectional shape of the piston 400. Specifically, the cross-sectional shape of the inner surface of the tube body 100 and the cross-sectional shape of the piston 400 are both polygonal or elliptical, preferably regular hexagonal. Such arrangement allows the piston 400 to be restricted from rotating by the inner wall surface of the tube body 100 when the driving screw 300 is rotated, so that the piston 400 can only move axially in the tube body 100 and push the toothpaste in the tube body 100 out of the discharge port 111. The utility model has a simple structure, ingenious design, easy use, and low processing difficulty and manufacturing cost.
[0044] Specifically, if Figure 4 As shown, a plurality of guide structures are arranged at circumferential intervals between the outer circumferential surface of the piston 400 and the inner wall of the tube body 100 to enhance the stability and reliability of the sliding advancement of the piston 400 in the tube body 100, wherein the strip groove 520 is arranged on the outer circumferential surface of the piston 400, and the raised rib 510 is arranged on the inner wall surface of the tube body 100.
[0045] In the present embodiment, the tube body 100 comprises an inner tube 110 and an outer tube 120 which are detachably fitted into each other, one end of the outer tube 120 is provided with an opening 121, and the other end thereof is open, one end of the inner tube 110 is provided with a discharge nozzle, and the other end thereof is open, so that the discharge nozzle passes through the opening 121 to be exposed to form a discharge nozzle 111, and the toothpaste is stored inside the inner tube 110, so that after all the toothpaste in the inner tube 110 is used up, it can be replaced by a new inner tube 110 fully loaded with toothpaste through disassembly, and can continue to be used, that is, the outer tube 120 and the toothpaste pushing structure are reusable, thereby saving the use cost, saving energy and protecting the environment, and facilitating the daily use of squeezing toothpaste.
[0046] Specifically, a structure that can slide axially but cannot rotate relative to each other is provided between the opening 121 and the discharge pipe mouth. Such a configuration prevents the inner tube 110 and the outer tube 120 from rotating relative to each other, and the inner tube 110 can be replaced and assembled by axially plugging and pulling out the inner tube 110. The disassembly process is simple and quick. The cross-sectional shape of the opening 121 and the cross-sectional shape of the discharge pipe mouth can both be polygonal or elliptical.
[0047] Furthermore, a connecting tube 210 is provided at the center of the inner wall of the rotating seat 200, and one end of the driving screw 300 is installed in the connecting tube 210, and one end of the driving screw 300 is tightly matched with the inner wall of the connecting tube 210. During assembly, one end of the driving screw 300 can be tightly inserted into the connecting tube 210 first, and then the other end of the driving screw 300 can be passed through the piston 400 and extended into the interior of the tube body 100, and finally the rotating seat 200 can be rotatably mounted on the outer tube 120. The structure is simple and easy to assemble.
[0048] Optionally, a structure that can be axially plugged in tightly and cannot rotate relative to each other is provided between the connecting cylinder 210 and one end of the driving screw 300. The connecting cylinder 210 is arranged at the center of the inner end wall of the rotating seat 200. The cross-sectional shape of the inner hole of the connecting cylinder 210 and the cross-sectional shape of one end of the driving screw 300 can both be polygonal or elliptical. In this way, the rotating seat 200 and the driving screw 300 can rotate synchronously.
[0049] In this embodiment, a first limiting convex ring 220 is circumferentially provided on the inner side wall of the rotating seat 200, and a second limiting convex ring 122 is circumferentially provided on the outer peripheral surface of the tube body 100, and the second limiting convex ring 122 is located on the inner side of the first limiting convex ring 220, so that the second limiting convex ring 122 abuts against the first limiting convex ring 220 to limit the rotating seat 200 from detaching from the outer tube 120, thereby improving the stability and reliability of the structure, wherein the rotating seat 200 and the other end of the outer tube 120 can rotate relative to each other, and the cross-sectional shape of the rotating seat 200 and the cross-sectional shape of the outer surface of the outer tube 120 are both perfect circles, so that the rotating seat 200 can be rotatable relative to the outer tube 120 to squeeze toothpaste, and the outer peripheral surface of the rotating seat 200 is evenly provided with a plurality of anti-slip protrusions (not shown in the figure).
[0050] Specifically, the piston 400 is provided with a threaded hole 411 axially extending therethrough, and the outer peripheral surface of the driving screw 300 is provided with an external thread so that the piston 400 is sleeved on the driving screw 300 through the threaded hole 411. The piston 400 includes a main body 410 and a convex head 420 arranged at the front end of the main body 410. The convex head 420 can be inserted into the discharge pipe mouth. In this way, the piston 400 can be pushed into the discharge pipe mouth through the convex head 420 to squeeze out all the residual toothpaste in the discharge pipe mouth, thereby further reducing the waste caused by the residual toothpaste in the tube body 100.
[0051] During use, the inner tube 110 of the tube body 100 is filled with toothpaste. The user can hold the tube body 100 and rotate the rotating seat 200, then the rotating seat 200 drives the driving screw 300 to rotate together, and the driving screw 300 is threadedly matched with the piston 400. Since the guide structure limits the piston 400 from rotating with the driving screw 300, when the driving screw 300 rotates, the piston 400 is driven to move along the axial direction of the tube body 100 under the guidance of the guide structure, and then the toothpaste is squeezed out from the discharge port 111 of the tube body 100, so as to facilitate the user's daily brushing. The utility model has a simple structure and ingenious design, low processing difficulty and production cost, and is simple to replace the inner tube 110 after using the toothpaste, and the user experience is good.
[0052] From the above description, it can be seen that the above embodiments of the utility model achieve the following technical effects:
[0053] The spiral-propelled toothpaste tube of the present invention is rotatably provided with a rotating seat 200 at the opening of the tube body 100. The user can hold the tube body 100 and rotate the rotating seat 200 to make the rotating seat 200 drive the driving screw 300 to rotate together. Since the driving screw 300 is threadedly matched with the piston 400, the piston 400 is driven to slide and advance axially under the guidance of the guide structure by the spiral force, so that the toothpaste in the tube body 100 is gradually pushed out from its discharge port 111 for daily brushing of teeth. The toothpaste is squeezed by setting the piston 400 to push, which can effectively reduce the toothpaste residue in the tube body 100, facilitate the user's daily squeezing of toothpaste, and thus bring a better user experience.
[0054] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.
[0055] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.
[0056] It should be noted that, in the description of the present application, unless otherwise clearly specified and limited, the terms "set, connect, connect, install" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present application can be understood according to specific circumstances.
[0057] In the description of the present invention, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0058] In addition, it should be noted that in the description of the present invention, the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application. In the description of the present invention, unless otherwise stated, the meaning of "multiple" refers to two or more.
[0059] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the protection scope of the present invention.
Claims
1. A spiral propulsion toothpaste tube, characterized in that: include: A tube body (100), wherein one end of the tube body (100) is provided with a discharge port (111), the other end of the tube body (100) is open, and the cross-sectional shape of the tube body (100) is a perfect circle; A rotating seat (200), the rotating seat (200) being rotatably covered at the opening of the tube body (100); A driving screw rod (300), the driving screw rod (300) extending along the axial direction of the tube body (100) and disposed in the tube body (100), and one end of the driving screw rod (300) is connected to the inner end wall of the rotating seat (200); A piston (400), wherein the piston (400) is movably disposed in the tube body (100), and a threaded hole (411) is formed through the piston (400) in the axial direction, so that the piston (400) is sleeved on the driving screw (300) through the threaded hole (411); A guide structure is provided between the outer peripheral surface of the piston (400) and the inner wall of the tube body (100), so as to guide the piston (400) to move axially in the tube body (100) through the guide structure.
2. The spiral propulsion toothpaste tube according to claim 1, characterized in that: The guide structure includes a raised rib (510) and a strip groove (520), one of the raised rib (510) and the strip groove (520) is arranged on the inner wall of the tube body (100), and the other of the raised rib (510) and the strip groove (520) is arranged on the outer peripheral surface of the piston (400), the raised rib (510) is slidably embedded in the strip groove (520), and the raised rib (510) and the strip groove (520) are both extended along the axial direction of the tube body (100).
3. The spiral propulsion toothpaste tube according to claim 1, characterized in that: The tube body (100) comprises an inner tube (110) and an outer tube (120) which are detachably fitted into each other, one end of the outer tube (120) is provided with an opening (121), and the other end thereof is open, one end of the inner tube (110) is provided with a discharge pipe opening, and the other end thereof is open, so that the discharge pipe opening passes through the opening (121) to be exposed, thereby forming the discharge pipe opening (111), and a structure which can slide axially but cannot rotate relative to each other is provided between the opening (121) and the discharge pipe opening.
4. The spiral propulsion toothpaste tube according to claim 1, characterized in that: A connecting cylinder (210) is provided at the center of the inner wall of the rotating seat (200), one end of the driving screw rod (300) is installed in the connecting cylinder (210), and a structure that can be axially plugged and assembled but cannot rotate relative to each other is provided between the connecting cylinder (210) and one end of the driving screw rod (300).
5. The spiral propulsion toothpaste tube according to claim 1, characterized in that: The inner side wall of the rotating seat (200) is provided with a first limiting convex ring (220) along the circumferential direction, and the outer peripheral surface of the tube body (100) is provided with a second limiting convex ring (122) along the circumferential direction, and the second limiting convex ring (122) is located on the inner side of the first limiting convex ring (220).
6. A spiral propulsion toothpaste tube, characterized in that: include: A tube body (100), wherein one end of the tube body (100) is provided with a discharge port (111), the other end of the tube body (100) is open, and the inner surface cross-sectional shape of the tube body (100) is polygonal or elliptical; A rotating seat (200), the rotating seat (200) being rotatably covered at the opening of the tube body (100); A driving screw rod (300), the driving screw rod (300) extending along the axial direction of the tube body (100) and disposed in the tube body (100), and one end of the driving screw rod (300) is connected to the inner end wall of the rotating seat (200); A piston (400) is movably disposed in the tube body (100), the cross-sectional shape of the piston (400) is adapted to the cross-sectional shape of the inner surface of the tube body, and a threaded hole (411) is axially penetrated through the piston (400) so that the piston (400) can be sleeved on the driving screw (300) through the threaded hole (411).
7. The spiral propulsion toothpaste tube according to claim 6, characterized in that: The tube body (100) comprises an inner tube (110) and an outer tube (120) which are detachably fitted into each other, one end of the outer tube (120) is provided with an opening (121), and the other end thereof is open, and one end of the inner tube (110) is provided with a discharge pipe opening, and the other end thereof is open, so that the discharge pipe opening passes through the opening (121) and is exposed, thereby forming the discharge pipe opening (111).
8. The spiral propulsion toothpaste tube according to claim 6, characterized in that: A connecting cylinder (210) is provided at the center of the inner wall of the rotating seat (200), one end of the driving screw rod (300) is installed in the connecting cylinder (210), and a structure that can be axially plugged and assembled but cannot rotate relative to each other is provided between the connecting cylinder (210) and one end of the driving screw rod (300).
9. The spiral propulsion toothpaste tube according to claim 6, characterized in that: The inner side wall of the rotating seat (200) is provided with a first limiting convex ring (220) along the circumferential direction, and the outer peripheral surface of the tube body (100) is provided with a second limiting convex ring (122) along the circumferential direction, and the second limiting convex ring (122) is located on the inner side of the first limiting convex ring (220).