阅读说明：本技术 包括轴环和密封件的夹紧装置 (Clamping device comprising a collar and a seal ) 是由 尼古拉斯·瑞格莱特 克里斯多弗·沙尼翁 于 2020-04-21 设计创作，主要内容包括：夹紧装置包括：轴环(10),其具有能够通过减小其直径而被夹紧的带件(12)；以及通过相对于轴环轴向保持而设置在带件(12)内的密封件(20)。密封件形成为自身缠绕并且其端部被配置为经由密封装置(24)相互配合在一起的条带(22)。密封件承受朝向带件的内表面的应力,并且被配置为克服该应力而弹性变形,以允许在密封件(20)和带(12)之间插入环形物体(1A)。(The clamping device includes: a collar (10) having a band (12) that can be clamped by reducing its diameter; and a seal (20) disposed within the band (12) by being axially retained relative to the collar. The seal is formed as a strip (22) wound on itself and having its ends configured to interfit together via a sealing means (24). The seal is subject to stress towards the inner surface of the band and is configured to deform elastically against the stress to allow insertion of an annular object (1A) between the seal (20) and the band (12).)

1. A clamping device, comprising: a collar (10), said collar (10) having a band (12) capable of assuming an undamped condition and a clamped condition of reduced diameter compared to the undamped condition; and a seal (20) arranged inside the band (12) by being axially retained with respect to the collar, the seal being formed as a strip (22) wound on itself and having its ends (22A, 22B) configured to be fitted together via sealing means (24), wherein, in an undamped condition of the band, the pre-mounted seal arranged inside the band is subjected to a stress directed towards the inner surface of the band, the seal being configured to be elastically deformed against this stress to allow an annular object to be inserted between the seal and the band (12).

2. The device according to claim 1, wherein the pre-mounted seal (20) is pre-stressed due to the presence of the band (12) in an undamped state around the seal.

3. A device according to claim 2, wherein the stress of the seal (20) towards the inner surface (12A) of the strip (12) is caused by the tendency of the diameter of the strip (22) to possess a diameter greater than that imposed by the strip in its undamped condition in which it is located.

4. Device according to claim 1, wherein the seal (20) has a rear edge (21B) provided with at least one insertion bevel (26), the insertion bevel (26) being inclined towards the winding axis of the strip, in a direction moving axially away from the seal from the rear edge.

5. Device according to claim 4, wherein the insertion ramp (26) is formed by a lug, the free end (26A) of which is bent inwards.

6. The device of claim 1, including an angular seal key (30, 32) configured to determine an angular position of the seal relative to the collar.

7. The device according to claim 1, wherein one of the two elements, the band (12) and the seal (20), has a wedge-shaped edge (13A) and the other of the two elements, the band (12) and the seal (20), has a wedge-shaped projection (28) able to cooperate with the wedge-shaped edge to retain the seal (20) against movement relative to the collar.

8. The device according to claim 1, wherein the seal (20) has a front edge (21A) provided with at least one abutment (28), said abutment (28) being configured to cooperate with a front edge (13A) of the strip (12) to retain the seal against movement relative to the strip in at least one direction (R).

9. The device of claim 8, wherein the abutment (28) comprises an outwardly curved lug.

10. The device of claim 1, wherein the band has a window (30), the edge (30A) of the window (30) forms a wedge-shaped edge, and the seal has a retaining lug (32) bent in the window.

11. The device of claim 1, wherein the sealing device (24) comprises a male/female engagement formation (24A, 24B) formed at an end of the strip (22) forming the seal.

12. The device according to claim 1, wherein the strip (12) and the seal (20) have a substantially constant diameter from one edge to the other.

13. The device according to claim 1, wherein the collar (10) has clamping lugs (14A, 14B), the clamping lugs (14A, 14B) projecting radially relative to the band (12) and being movable relative to each other to clamp the collar.

14. A pipe clamping assembly comprising a clamping device according to claim 1 and a pipe (1), an end (1A) of the pipe (1) being insertable between the seal (20) and the strip (12).

15. Assembly according to claim 14, comprising a tubular position key (32, 3A), the tubular position key (32, 3A) determining the angular position of the tubular (1) with respect to at least one of the two elements, the seal (20) and the collar (10).

16. The combination of claim 14, wherein the seal has a tubular position key lug (32) projecting radially outwardly from the seal (20) and configured to engage in a slot (3B) formed at an end of the tubular (1).

17. Assembly according to claim 14, wherein the seal comprises an extraction-prevention member configured to cooperate with a window (3B, 3' B, 3 "B) of the tubular (1) to prevent extraction of the seal from the tubular.

Technical Field

The present disclosure relates to a clamping device comprising a collar. In particular, the invention relates to a device for clamping a pipe by means of a collar. It relates in particular to joining two pipes which are fitted together, the collar being clamped to the end of an outer pipe which is mounted on the inner pipe.

Background

Patent US 6199921 discloses a clamping device for fitting two pipes together, the outer pipe having a cut-out facilitating its deformation during clamping. Thus, the sealing of the connection between two pipes is achieved by: the outer tube is deformed enough to bring its inner periphery into close contact with the outer periphery of the inner tube; and the outer tube cut promoting its deformation is correctly bridged by the clamping ring.

In order to connect two pipe elements which are fitted together in a sealing manner, it is also conceivable to have a seal at the interface between the two pipe elements and to clamp the fitted pipe elements. For example, the seal may be disposed between the inner periphery of the outer tube and the outer periphery of the inner tube. However, placing such a seal and holding it in place during clamping can be difficult, thereby complicating the operations of assembling and clamping the pipe elements.

To overcome these drawbacks, patents EP 2598785 and EP 3232107 propose a system in which the seal is pre-mounted in a collar for the assembly of the gripping pipe elements. More specifically, the system includes a gasket including a closed annular portion forming a seal and lugs connecting the seal to a collar. Initially, the annular seal is held at a distance from the inner circumferential surface of the collar to engage the outer tube between the seal and the inner circumferential surface. The inner tubes are then sequentially engaged to contact the seal. The device is particularly suitable for clamping two pipe elements fitted together and having radially projecting flared surfaces which act as bearings for a clamping collar comprising a recess which can receive these radially projecting flared surfaces, the closed annular seal itself having a frustoconical shape, adapted to these flared surfaces.

Patent application US 2011/0018263 discloses a clamping device for connecting two pipe elements. The device comprises a collar and a seal intended to be positioned between two connected tubulars. For this purpose, the seal is premounted on the end of one of the tubes, in particular by means of an adhesive. Thus, the clamping device cannot be shown in its entirety, including the collar and the seal, which can be mounted on the pipe to connect them. In other words, in this device, the seal cannot be pre-installed in the band.

Patent application EP 1816325 also discloses a clamping device comprising a collar and a seal, wherein the seal is not pre-mounted in the strip.

Disclosure of Invention

There is a need to improve the prior art and in particular to propose a device comprising a seal pre-mounted in a collar, which seal is generally adapted to clamp the fitting-together pipe elements (even if these do not have a radially expanded shape).

The object of the present invention is to propose a clamping device which at least substantially overcomes the above-mentioned disadvantages.

Accordingly, the present disclosure relates to a clamping device comprising: a collar having a band capable of assuming an unclamped state and a clamped state, the diameter of the band in the clamped state being smaller than the diameter of the band in the unclamped state; and a seal disposed inside the band by being axially retained with respect to the collar, the seal being formed as a strip wound on itself and having its ends configured to be fitted together by a sealing arrangement, wherein, in an undamped state of the band, a pre-mounted seal arranged inside the band is subjected to a stress directed towards an inner surface of the band, the seal being configured to elastically deform against the stress to allow insertion of an annular object between the seal and the band.

Optionally, the pre-installed seal is pre-stressed by the presence of the tape in an undamped state around the seal.

Alternatively, the stress of the seal towards the inner surface of the strip is caused by the tendency of the diameter of the strip to possess a diameter greater than that imposed by the strip in its undamped state in which the strip is located.

Optionally, the seal has a rear edge provided with at least one insertion ramp inclined towards the winding axis of the strip in a direction moving axially away from the seal from said rear edge, said ramp optionally being formed by a lug, the free end of which is bent inwards.

Optionally, the device comprises an angular seal key configured to determine the angular position of the seal relative to the collar.

Optionally, one of the two elements, the band and the seal, has a tapered edge and the other element has a tapered projection capable of cooperating with the tapered edge to retain the seal against movement relative to the collar.

Optionally, the seal has a leading edge provided with at least one abutment configured to cooperate with the leading edge of the tape to retain the seal against movement relative to said tape in at least one direction, the abutment optionally comprising an outwardly curved lug.

Optionally, the band has a window, the edges of the window forming a wedge-shaped edge, and the seal has a retaining lug projecting in the window.

Optionally, the sealing means comprises a male/female engagement formation formed at the end of the strip forming the seal.

Optionally, the band and seal have a substantially constant diameter from one edge to the other.

Optionally, the collar has clamping lugs which project radially relative to the band and are movable relative to one another to clamp the collar.

The invention also relates to a pipe clamp assembly comprising a clamp device of the above-mentioned type and a pipe, the end of which can be inserted between the seal and the band.

Optionally, the combination includes a tubular position key that determines the angular position of the tubular relative to at least one of the elements, the seal and the collar.

Optionally, the seal has a tubular position key lug projecting radially outwardly from the seal and configured to engage in a slot formed at an end of the tubular.

Optionally, the seal comprises an anti-extraction member, in particular an anti-extraction tab, configured to cooperate with a window of the tube to prevent extraction of the seal from the tube.

The present disclosure will be well understood and its objects will appear better after reading the following detailed description of one embodiment and its variants, represented by way of non-limiting example.

Drawings

Figure 1 shows a pipe clamp assembly in an exploded perspective view, the pipe clamp assembly including a clamp device according to the present disclosure.

FIG. 2 is a perspective view of a clamping device including a collar and a seal.

Fig. 3 shows the clamping device of fig. 2 in a state in which the sealing element is not arranged in the band of the collar.

Figure 4 is a perspective view showing the clamping device of the previous figures mounted on the end of an outer pipe before the inner pipe is fitted into the outer pipe.

Fig. 5 is a view similar to the modification of fig. 1.

Fig. 6 is a view similar to fig. 1 and 5 of another variation.

Detailed Description

The assembly shown in fig. 1 comprises a clamping device which itself comprises a collar 10 and a seal 20. The assembly further comprises an outer tube 1 and an inner tube 2. The inner tube 2 is configured to fit into the outer tube 1 to connect two pipes. More specifically, the inner tube 2 is fitted into the end 1A of the outer tube 1, and then the clamping collar 10 is placed around the end 1A of the outer tube 1 to clamp the assembly thus made. In this assembled state, the seal 20 itself is arranged between the inner and outer pipe. For assembly, it will be understood that the seal 20 is placed in the end 1A of the tubular 1, the clamping collar 10 is arranged around the end 1A of the tubular 1, and the inner tube 2 is assembled into the seal 20.

In this case, the portions of the two pipe members 1 and 2 fitted to each other form a cylindrical surface without bulging. However, the end 1A of the tube 1 is delimited by a shoulder 1 "a on the opposite side to its free end 1' a. The end 1A is thus widened, while the remaining part 1B of the tube 1 has the same diameter as the tube 2.

Note that the seal 20 is formed in a strip 22 that is wound upon itself and whose ends 22A and 22B are fitted together via sealing means 24, respectively. In this case, the sealing means comprise a notch 24A formed at the end 22A and defined between deformable edges 24' a, and a tab 24B formed at the end 22B. The edge 24' a is slightly inclined so that the width of the recess 24A gradually increases towards the free end of the end portion 22A. Similarly, the width of tab 24B gradually increases away from the free end of end 22B. Thus, the more the tab 24B penetrates into the notch 24, the more stress is placed on the contact between the edge of the tab and the edge of the notch until a slight deformation of the edge of the notch is caused. The contact area between the tab and the edge of the recess thus forms a sealing contact. In this case, the edges of the cut-outs 24A are formed on deformable lugs.

This is an example of a sealing arrangement that allows the mating between the ends 22A and 22B of the strip 22 to form the seal 20. Other sealing arrangements may be provided, whether or not they are provided directly on the strip 22 in this case, integral therewith, or added to, for example, more deformable materials. Sealing can also be obtained by the baffle effect without having to apply the contact and deformation stresses described above.

In any event, the seal 20 is open, that is, the ends of the strip 22 in which the seal 20 is formed can be moved relative to one another to increase or decrease the diameter of the seal. In this case, the sealing member 24 is integrally formed in the strip 22, and thus the sealing member 24 may be considered to be formed of a strip wound on itself and having various slits and lugs, which will be described below. In particular, the strip 22 is of metal, in particular of stainless steel type. The strip 22 may be made of a single material or may have multiple materials, such as multiple layers or base strips stacked on top of each other. For example, a strip may comprise two similar base strips stacked on top of each other. Thus, the strip may comprise a substantially metallic strip supporting a substantially mica-based strip. The two base strips may be secured to each other by any suitable means, such as by gluing or the like, or even mechanically. Such mechanical means may be the lugs of the base metal strip being folded over the base mica strip or being engaged in holes or notches in the base strip to retain it on the base metal strip. For example, mica-based tapes may be manufactured under the trademark high temperature resistantAnd comprises more than 90% by mass of mica and less than 10% by mass of a binder.

Whatever the material, in particular when it is made of metal, the strip 22 may have been subjected to a surface treatment, for example based on lamellar zinc, so as to constitute an outer layer promoting sealing. Also, the collar 10 and optionally the pipes 1 and 2 may be metallic.

Fig. 2 will now be described, in which the seal 20 is disposed inside the band 12 of the collar 10. The band 12 defines a cylindrical shape and the seal 20 is disposed within the cylinder. In fig. 2, the seal 20 is pre-installed in the strip, so that the collar and the pre-installed seal form a part that can be brought to the end of the pipe element. More specifically, as shown in fig. 4, by inserting the end of the first pipe fitting 1 between the seal and the band, the component formed by the collar and the pre-installed seal can be brought to the end of the first pipe fitting 1. Then, the second pipe member 2 is fitted into the first pipe member 1, and then the band member is clamped to sealingly connect the two pipe members.

By comparing fig. 2 with fig. 1 and 3, it can be seen that in fig. 2, the seal 20 is pre-stressed by the band 12 of the collar surrounding the seal. In fact, in the free state, the diameter of this seal 20 is greater than the diameter of the seal defined by the band of the collar. Thus, when the seal is in the collar, the inner surface 12A of the band 12 stresses it so that its diameter is smaller than its diameter in the free state. In other words, the sealing member 20 naturally presses against the band 12 of the collar 10. As an open seal, the seal may act like a spring, with a diameter that increases and decreases depending on whether the ends 22A or 22B forming the strip 22 are closer to or farther from each other.

When the gripping device is in the condition shown in fig. 2, the sealing element 20 is pressed against the inner surface of the strip 12, and an annular body, in this example the end 1A of the pipe element 1, can be inserted between the sealing element and the strip 12. To this end, it is sufficient to bring the ends of the strip 22 forming the seal close to each other, reducing the diameter of the seal, so as to arrange an annular space between the seal and the strip, to allow the insertion of the end 1A of the pipe element 1. In the present example, in order to facilitate this approach of the strip ends and therefore reduce the diameter of the seal, the seal 20 has a rear edge 21B, the rear edge 21B being provided with lugs 26 forming an insertion ramp.

More specifically, each lug 26 extends axially towards the rear of the seal, with its free end 26A bent inwards. The outer surface of the lugs 26 thus forms a ramp on which the free end of the annular object (in this case the end 1A of the pipe element 1) can slide when inserted between the seal and the band. A plurality of angularly distributed lugs 26 may be provided. In this case, the seal comprises six lugs 26.

Within the meaning of the present invention, the qualifiers "front" and "rear" are understood with respect to the assembly direction of the pipe elements. Thus, the rear edge 21B of the seal 20 is the edge thereof which is farthest from the free end 1' a (front end) of the pipe member 1 from which the pipe member 1 is fitted to the pipe member 2 when the seal is disposed in the end portion 1A of the pipe member 1. In contrast, when the seal is arranged in the pipe element 1, the front edge 21A of the seal 20 is the edge located closest to the free end 1' a of the pipe element. With respect to the tube 1, the aforementioned shoulder 1 "a is provided at the rear of the free end 1' a. As for the pipe member 2, its free end 2A facing the pipe member 1 is its front end.

Furthermore, the elements arranged towards the axis of the pipe, collar and seal will be referred to as "inner". When the assembly is mounted, these various elements are concentric with their axes coinciding on axis a.

When the seal 20 is disposed inside the band 12, the seal 20 is axially retained relative to the collar 10. In this case, a plurality of elements contribute to the axial retention. In one aspect, the leading edge 13A of the band forms a wedge-shaped edge against which a wedge-shaped projection 28 formed on the seal 20 is in abutting engagement. In this case, these wedge-shaped projections 28 are formed by radially projecting lugs 28 formed on the leading edge 21A of the seal 20. The free ends of these lugs enclose a circle having a diameter which is larger than the inner diameter of the strap 12 in its non-clamped state. Thus, the seal 20 can be placed in the collar by engaging the rear edge of the seal 20 into the collar from the front edge of the band (the wedge-shaped edge) until the lugs 28 abut against the wedge-shaped edge 13A.

Once seal 20 is in place in the collar, this axial retention force resists rearward (i.e., in direction R as shown in fig. 3 and 4) movement of the seal relative to the collar. Thus, as shown in fig. 4, once the clamping system is in place at end 1A of tubular 1, tubular 2 can be fitted into seal 20 without having to push seal 20 back in direction R.

Furthermore, as can be seen in particular in fig. 2, the strip 12 has a window 30, the edge 30A of which forms a wedge-shaped edge, and the seal has a radial projection which engages in the window. In this case the radial projection is formed by a retaining lug 32 provided with the seal, and this bent lug is bent through the window 30 when the seal is mounted in the collar. In particular, the lugs 32 are cut in the strip 22 forming the seal, the cuts 33 remaining in the strip when the lugs are bent.

To place the seal 20 in the collar 10, it is sufficient to compress the seal slightly during the above-mentioned axial insertion, so that the free ends of the bent lugs 32 define a diameter dimension smaller than that of the band 12, which, as mentioned above, is inserted in the collar in the undamped condition of the band.

In this case it can be seen that the strip 12 has two identical windows 30 arranged such that one window can replace the other when the collar is pivoted 180 degrees to invert the leading and trailing edges 13A, 13B of the strip. Thus, the seal 20 can be properly placed in the band whether the collar is in either of these two positions.

The windows 30 and lugs 32 just mentioned serve, on the one hand, to assist in the axial retention of the seal relative to the collar. In fact, when the lugs are engaged in the windows, the contact between the lugs and the edge 30A of the windows prevents the seal from moving axially with respect to the collar in the direction R and in the opposite direction.

On the other hand, the windows 30 and lugs 32 act as angular sealing keys, as the correct engagement of the lugs in the windows determines the angular position of the seal relative to the band. This allows ensuring that the end of the strip 22 in which the seal is formed is arranged in a position other than the opening of the collar, when the collar is open as in the example shown.

Returning to fig. 1, it can be seen that the end 1A of the tube has a slot 3, which slot 3 in this case comprises an open portion 3A opening onto the free end 1A of the tube and a window portion 3B whose profile is closed or almost closed. Thus, by reducing the width of the slot 3 to obtain a reduction in the diameter of the end 1A, it is possible to clamp the end 1A on the tube 2A. The slot 3 can also help to determine the angular position of the tubular relative to the gripping system. In fact, during the insertion of the portion 1A of the pipe element in the annular space formed between the sealing element and the band 12, the open portion 3A of the slot 3 can receive the above-mentioned lug 32 of the sealing element 20. Thus, the lugs 32 do not prevent the pipe element 1 from being inserted in the desired position, and moreover, since the angular position of the seal relative to the collar is determined itself, the cooperation between the lugs 32 and the slots 3A determines the angular position of the pipe element relative to the seal and therefore relative to the collar.

The device according to the invention also comprises an anti-extraction member for the seal with respect to the fitting 1. In this case, the seal 20 has an anti-extraction tab 34, in this case the anti-extraction tab 34 is formed by a tab cut out on the strip 22 and bent slightly outwards, so that the free edge of the tab is positioned towards the front edge 21A of the seal 20, while its crease 34' for attachment to the current portion of the strip is positioned backwards. Under these conditions, it will be understood that the thrust of the end 1A in the forward direction F (see fig. 1 and 2) during the engagement of the end 1A between the seal and the collar tends to push back the tabs 34 inwards. In other words, the tab 34 disappears when the end 1A of the pipe is inserted. However, this deformation of the tab is elastic, which is then able to resume its bent shape in the closed window portion 3B of the slot 3 of the tube. Thus, the cooperation between the tab 34 and the front edge 3B' of the window 3B prevents the extraction of the seal from the tube in the direction F.

In fig. 4, the end 1A of the pipe 1 is inserted between the seal 20 and the inner periphery of the band 12 of the collar. It can also be seen that the tab 24B formed at the end 22B of the strip 22 forming the seal has been moved forward into the notch 24A formed at the end 22A of the same strip. Thus, the edge of the tab 24B mates with the edge 24' A of the notch 24A, forming a sealed contact area. Furthermore, the seal is retained in the collar and the pipe elements by the aforementioned lugs 28 and 32 and lugs 34, the lugs 34 being hidden by the band in fig. 4. In this case, the end of the pipe element 2 can be inserted into the assembly formed by the pipe element 1, the collar 10 and the seal 20 being pre-mounted on the end 1A of this pipe element 1.

Note that the front edge 2A of the tube 2 has a recess 2' a. The notch may act as an angular position key by cooperating with an inwardly folded key lug 27 on the rear edge of the seal 20. This lug 27 differs from the previously described lug 26 in that it is folded inwardly closer to the rear edge 21B of the seal.

As mentioned above, the clamping collar is open. In this case the band is provided with clamping lugs 14A and 14B, respectively, which are bent radially outwards, a slot 15 being defined between the clamping lugs 14A and 14B, the slot 15 defining the opening of the collar. These lugs can be moved relative to each other to grip the collar. In this case, the movement is an approaching movement by means of the clamping lever 16A. More specifically, the collar comprises a clamping screw 16, in this case the ends of which are held at the rear of the clamping lugs 14A and 14B by a head 16B and a nut 16C, respectively, of the screw (possibly via a spacer 16D). In the particular case of the clamping lugs 14A and 14B, the rear of a clamping lug is the side of the lug opposite the other clamping lug. Thanks to the aforesaid corner key, on the one hand, the slot 3 of the tube 1 is angularly offset with respect to the slot 15 of the collar 10 defined between its clamping lugs, and on the other hand, the end of the strip 22 in which the seal 20 is formed is also angularly offset with respect to both the slot 3 of the tube and the slot 15 of the collar.

Fig. 5 will now be described, in which the same reference numerals as in the previous figures are repeated, except for those relating to the slots of the tube 1. Wherein, in figure 5, the slot is indicated by the reference numeral 3 'and is made up of several elementary axial slots, in particular a front slot 3' a opening on the free edge 1'a of the tubular element, a closed slot 3' B at the rear of the slot 3'a and closed transverse slots 3' C on either side of the slots 3'a and 3' B. The clamping system is similar to that just described, the only difference being the positioning of the anti-extraction tabs 34, axially aligned with the lugs 32 to be housed in the closed slots 3' B of the fitting 1, when the anti-extraction tabs 34 are engaged in the annular space formed between the seal and the collar. Of course, the positioning lug 34 can be chosen in a different way, for example, so that it cooperates with one of the transverse slots 3' C.

In the example of fig. 6, the slots 3 "of the tube 1 are still different and in this case have a closed slot 3" B of general Y-shape and a V-shaped recess 3 "a arranged in the cavity formed between the two branches of the Y, which opens on the front edge 1' a of the tube 1. In this case, the lug 32 of the seal 20 is formed on the front edge 21A of the seal to be naturally accommodated in the recess 3 "a. The anti-extraction tab 34 is substantially aligned with the lug 32 so as to be received in the enlarged tail of the Y-shape 3 "B.

Fig. 5 and 6 are examples showing the positions of the withdrawal prevention member, which can realize the tube position key and the seal in different configurations, with respect to the tube.

The just described seal is first pressed against the inner surface of the band of the collar. However, by elastically deforming the seal against its initial stress, the end of the outer tube may be engaged between the inner surface of the band and the seal. Once insertion is complete, the seal will naturally tend to apply stress towards the inner periphery of the outer tubular member and then engage in the collar. Thus, the inner tube can be easily placed, and the seal does not constitute an obstacle to the installation, since it is pressed against the inner surface of the outer tube and is axially retained with respect to the collar. The insertion of the end of the outer tube between the seal and the band of the collar can be facilitated, if desired, by the presence of at least one insertion ramp. The possible presence of the corner sealing key ensures that the end of the strip forming the seal is offset with respect to the opening of the collar, in particular when the collar is open.

Note that the band and seal of the collar have a substantially constant diameter from one edge to the other. Thus, the band of the collar and the seal define a cylindrical surface. In particular, they are formed by flat strips wound on themselves.