JP2012081580A - Air injection device for polishing jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air injection device for a polishing jig, which has high sealability, is not likely to come off from a body of an injection port member, and is provided with an inexpensive sealing member.SOLUTION: The device is provided with the injection port member 4 to be inserted into an air injection port 16 of the polishing jig 2. The injection port member 4 is provided with a cylindrical body 33 and the sealing member 34 attached to an outer peripheral part of the body 33. The outer peripheral part of the body 33 has a peripheral wall 42 parallel to an outer peripheral surface 33a of the body 33, and an annular groove 41 having a pair of side walls 43 and 44 extended radially outward from the peripheral wall 42. The sealing member 34 is formed in an annular shape which extends all over a circumferential direction of the annular groove 41 by an elastic body, and inserted into the annular groove 41. An outer diameter of the sealing member 34 is made larger than an inner diameter of the air injection port 16. A gap S to be sealed by the elastically deformed sealing member 34 is formed between the sealing member 34 and the annular groove 41.

Description

  The present invention relates to an air injection device for a polishing jig for injecting air into a polishing jig having a balloon member that is inflated by air pressure.

  2. Description of the Related Art Conventionally, as a polishing apparatus for polishing a lens surface of a spectacle lens, for example, as described in Patent Document 1, there is an apparatus using a polishing jig provided with a balloon member that is inflated by air pressure. The polishing jig shown in Patent Document 1 includes the balloon member, a support member that supports the balloon member, and a valve that opens and closes an air passage formed in the support member.

The air passage is formed to extend from the air inlet opening at one end surface of the support member into the balloon member. The said valve | bulb is a thing of the structure opened with the pressure of the air supplied to the said air inlet.
The air is injected into the balloon member by attaching a polishing jig to the air injection device. This air injection device includes an installation table on which a polishing jig is placed, an injection port member inserted into the air injection port, an air supply device for discharging air from the air outlet of the injection port member, and the like. I have.

  The inlet member is attached in a state of projecting to the installation base so as to be inserted into the air inlet by placing a polishing jig on the installation base. The inlet member is constituted by a main body formed in a disc shape and a seal member for sealing between the main body and the air inlet. The air outlet opens on the outer peripheral surface of the main body. The seal member is formed in a cup shape surrounding the outer peripheral portion of the main body by an elastic material, and is configured to be held by the main body by its own elasticity.

  The outer peripheral portion of the seal member bulges outward in the radial direction and comes into close contact with the wall surface of the air injection port when air is discharged from the air outlet of the main body while being inserted into the air injection port together with the main body. By deforming the seal member in this way, the gap between the inlet member and the air inlet is sealed. The air discharged from the air outlet flows into the air inlet from the center of the seal member through the gap between the main body and the seal member.

JP 2004-106117 A

  However, since the sealing member shown in Patent Document 1 is a specially-shaped special part that covers the main body of the inlet member, there is a problem that the manufacturing cost of the air injection device for the polishing jig increases. Further, when the seal member is deteriorated after being used for a long period of time, for example, the force for sandwiching the main body may be reduced. In such a case, the seal member is easily detached from the main body of the inlet member.

  For example, when the polishing jig is removed from the air injection device after the air injection is completed, the sealing member may come off the main body of the injection port member in a state where the seal member is attached to the air injection port. If the seal member is detached from the main body, the operation of loading the polishing jig into the polishing apparatus is interrupted, and the polishing efficiency is lowered. In order to solve such a problem, it is necessary to avoid the deterioration of the sealing performance of the sealing member.

  The present invention has been made to solve such problems, and has high sealing performance and does not easily come off from the main body of the inlet member, and is also an air injection for a polishing jig provided with an inexpensive sealing member. An object is to provide an apparatus.

  In order to achieve this object, an air injection device for a polishing jig according to the present invention includes an injection port member inserted into an air injection port of an eyeglass lens polishing jig having a balloon member that is inflated by air pressure, and the spectacle lens. A polishing jig installation base having an installation surface on which the polishing jig is mounted and supporting the inlet member in a state of protruding from the installation surface, and formed on the protruding side end of the injection member. An air supply device that discharges air from the air outlet, and the air inlet opens to a mounting surface facing the installation surface of the spectacle lens polishing jig so that the opening shape is circular, The inlet member includes a main body having an air passage formed in a columnar shape and connected to the air outlet, and a seal member attached to an outer peripheral portion of the main body. A peripheral wall parallel to the outer peripheral surface of the An annular groove having a pair of side walls extending radially outward from the peripheral wall is formed, and the seal member is formed in an annular shape extending along the annular groove over the entire circumferential direction by an elastic body. The seal member is formed so that the outer diameter of the seal member is larger than the inner diameter of the air inlet, and the inlet member is inserted into the air inlet between the seal member and the annular groove. Thus, a gap to be sealed by the sealing member elastically deformed is formed.

In the present invention according to the present invention, the gap is formed between the side wall of the annular groove and the seal member.
In the present invention according to the present invention, the gap is formed between the peripheral wall of the annular groove and the seal member.

According to the present invention, the seal member is compressed into the gap formed between the annular groove by being inserted into the air inlet together with the main body of the inlet member. For this reason, since the sealing member does not lose elasticity even in a state where it is compressed in the annular groove, it reliably seals between the annular groove and the air inlet. Further, since the seal member is inserted into the annular groove of the inlet member, it is not easily detached from the inlet member. Furthermore, an inexpensive off-the-shelf product can be used for the seal member.
Therefore, according to the present invention, it is possible to provide an air injection device for a polishing jig that has a high sealing performance, does not easily come off from the inlet member, and includes an inexpensive seal member.

It is sectional drawing which shows the structure of a grinding | polishing jig | tool and an installation stand. It is sectional drawing which expands and shows the air inlet part of a grinding | polishing jig | tool. It is sectional drawing of the inlet member attached to the installation stand. It is sectional drawing which shows the state in which the inlet member was inserted in the air inlet. It is sectional drawing which shows other embodiment of an inlet member. It is sectional drawing which shows the state in which the inlet member was inserted in the air inlet. It is sectional drawing which shows other embodiment of an inlet member. It is sectional drawing which shows the state in which the inlet member was inserted in the air inlet. It is sectional drawing which shows the dimension of each part at the time of experiment. It is a figure for demonstrating an experimental result.

(First embodiment)
Hereinafter, an embodiment of an air injection device for a polishing jig according to the present invention will be described in detail with reference to FIGS.
An air injection apparatus 1 for a polishing jig shown in FIG. 1 includes an installation base 3 on which a spectacle lens polishing jig 2 is placed, an inlet member 4 protruding from the installation base 3, and the inlet member. 4 and an air supply device 6 connected via an air passage 5.

  The polishing jig 2 is equivalent to the polishing jig described in Patent Document 1, and is loaded into a polishing apparatus (not shown) after air is injected by the air injection apparatus 1 according to the present invention. The polishing jig 2 according to this embodiment includes a rubber balloon member 11 that is inflated by air pressure, and a support member 12 for supporting the balloon member 11. The balloon member 11 is inflated when air is supplied from an air supply device 6 to be described later, and a polishing pad (not shown) is mounted in a state where the surface is inflated to have a predetermined curvature. The predetermined curvature is the curvature of the lens surface of the spectacle lens to be polished.

  The support member 12 is formed with an air passage 13 for injecting air into the balloon member 11 and discharging air from the balloon member 11. The air passage 13 includes a circular hole 14 having a circular cross section formed in the support member 12 and a valve 15 provided between the circular hole 14 and the balloon member 11. One end of the circular hole 14 located on the side opposite to the balloon member 11 is opened as an air inlet 16 on the flat mounting surface 12 a of the support member 12. The air inlet 16 is formed to open on the mounting surface 12a so that the opening shape is circular, and to extend in a direction orthogonal to the mounting surface 12a.

  As shown in FIG. 2, the valve 15 includes a check valve 23 including a ball 21 and a conical coil spring 22, and an exhaust mechanism 25 having an exhaust pin 24 facing the ball 21. The check valve 23 has a structure that allows air to pass only into the balloon member 11 from the air inlet 16 side. The exhaust pin 24 is for pressing the ball 21 against the spring force of the conical coil spring 22. The exhaust pin 24 is supported by the valve housing 26 so that the exhaust pin 24 can move back and forth between the retracted position shown in FIG. 2 and the exhaust position where the front end of the exhaust pin 24 presses the ball 21. The exhaust pin 24 is biased in a direction away from the ball 21 by a conical coil spring 27 provided between the exhaust pin 24 and the valve housing 26.

  As shown in FIG. 1, the installation table 3 is formed in a plate shape having a flat installation surface 3a on which the polishing jig 2 is placed. The installation table 3 is supported by a moving device (not shown) and is configured to be movable between a jig attaching / detaching position where a polishing jig is attached / detached and a height measuring position (not shown). Has been. The height measurement position is a position at which a height measuring device (not shown) measures the height of the balloon member 11 inflated with air pressure.

  The balloon member 11 swells when air is supplied from an air supply device 6 to be described later in a state where it is placed on the installation table 3. The curvature of the surface of the balloon member 11 changes corresponding to the height of the balloon member 11. For this reason, air is supplied to the balloon member 11 until the height measured by the height measuring device matches the target curvature (the curvature of the lens surface of the spectacle lens to be polished). The

As shown in FIG. 3, the inlet member 4 includes a cylindrical main body 33 having a screw portion 32 screwed into a screw hole 31 of the installation base 3 and protruding from the installation surface 3a. And a sealing member 34 made of an elastic body mounted on the outer periphery of 33.
The screw hole 32 is connected to the air supply device 6 through the air passage 5. The air supply device 6 uses an air compressor (not shown) as an air supply source.

  The outer diameter A of the main body 33 having a cylindrical shape is formed smaller than the inner diameter B (see FIG. 2) of the air inlet 16 of the polishing jig 2. A through hole 35 is formed in the axial center portion of the main body 33. One end of the through hole 35 is opened as an air outlet 36 on the projecting side end surface of the main body 33. The other end of the through hole 35 is connected to the air passage 5.

  An annular groove 41 for holding a seal member 34 to be described later is formed on the outer peripheral portion of the main body 33 so as to extend in the circumferential direction. The annular groove 41 according to this embodiment is formed by a peripheral wall 42 parallel to the outer peripheral surface 33 a of the main body 33, and a first side wall 43 and a second side wall 44 that extend radially outward from the peripheral wall 42. Yes. The first side wall 43 and the second side wall 44 are formed to be parallel to the installation surface 3 a of the installation table 3.

The seal member 34 is made of an elastic body and is inserted into the annular groove 41. The shape of the sealing member 34 is an annular shape extending along the annular groove 41 over the entire region in the circumferential direction. The seal member 34 used in this embodiment is an off-the-shelf O-ring.
The inner diameter d1 of the seal member 34 is formed to be equal to the outer diameter D of the peripheral wall 42. Further, the thickness W of the seal member 34 is formed to be smaller than the groove width G (interval between the first side wall 43 and the second side wall 44) G of the annular groove 41. That is, in a state where the seal member 34 is inserted into the annular groove 41, there is a gap between at least one of the first side wall 43 and the second side wall 44 of the annular groove 41 and the seal member 34. S is formed. Further, the outer diameter d2 of the seal member 34 is formed larger than the inner diameter B of the air inlet 16.

  That is, the seal member 34 is inserted into the air inlet 16 of the polishing jig 2 together with the main body 33 of the inlet member 4 as shown in FIG. Pressed. At this time, the seal member 34 is elastically deformed toward the gap S because the inner peripheral portion is in contact with the peripheral wall 42 and deformation in the radial direction is restricted. As a result, the gap S is sealed by the elastically deformed seal member 34. In other words, the gap S is formed to be sealed by the sealing member 34 that is elastically deformed by inserting the inlet member 4 into the air inlet 16.

  The seal member 34 is not limited to an O-ring, and any elastic body can be used as long as it has a shape extending in the entire circumferential direction of the annular groove 41. For example, the seal member 34 may be an elastic body formed in a ring shape, or may be an elastic body having a shape in which the ring is cut at one place in the circumferential direction. If a ring-shaped elastic body cut in one place as described above is used as the sealing member 34, it can be expanded in a C-shape, so that the operation of inserting into the annular groove 41 and the operation of removing from the annular groove 41 are easy. Can be done.

  As a material of the elastic body forming the seal member 34, for example, fluoro rubber (FPM) can be used. Since fluororubber has a self-lubricating property, the resistance decreases when the sealing member 34 is inserted into and removed from the air inlet 16 of the polishing jig 2. For this reason, the polishing jig 2 is easily attached and detached, and the seal member 34 is hardly worn.

  In order to inject air into the balloon member 11 of the polishing jig 2 using the polishing jig air injection device 1 configured as described above, first, the mounting table 3 positioned at the jig mounting / dismounting position is applied. The polishing jig 2 is placed, and the inlet member 4 is inserted into the air inlet 16 as shown in FIG. When the inlet member 4 is inserted into the air inlet 16, the seal member 34 is compressed and elastically deformed to enter the gap S. The seal member 34 does not lose its elasticity even when it is compressed in the annular groove 41. For this reason, the seal member 34 is in close contact with the peripheral wall 42 of the annular groove 41, the first and second side walls 43, 44, and the wall surface 16 a of the air inlet 16 with an appropriate elasticity, and the inlet member 4 And the air inlet 16 are sealed.

  Next, the installation base 3 is moved to the height measurement position, the air supply device 6 is operated, and air is discharged into the air passage 5. The air in the air passage 5 flows into the air inlet 16 through the through hole 35 of the inlet member 4. At this time, since the seal member 34 is in close contact with the walls 42 to 44 of the annular groove 41 and the wall surface 16 a of the air inlet 16, air leaks between the air inlet 16 and the inlet member 4. Never do.

  The air supplied into the air inlet 16 flows into the balloon member 11 through the valve 15 when the pressure in the air inlet 16 rises and the valve 15 opens. The balloon member 11 expands when air is injected. The air is injected into the balloon member 11 until the height of the balloon member 11 measured by the height measuring device reaches a target height. This target height is a height corresponding to the curvature of the spectacle lens to be polished.

  The installation table 3 is returned to the jig attachment / detachment position after the air injection into the balloon member 11 is completed as described above. The polishing jig 2 is removed from the installation table 3 after the installation table 3 has moved to the jig attachment / detachment position, and loaded into the polishing apparatus. When the polishing jig 2 is removed from the installation table 3, a force is applied to the seal member 34 so as to pull it off from the inlet member 4. However, since the seal member 34 is inserted and held in the annular groove 41, it does not come off from the inlet member 4.

  Therefore, the air injection device 1 for a polishing jig according to this embodiment uses an off-the-shelf O-ring as the seal member 34, so that the manufacturing cost can be kept low. In addition, the air injection device 1 for a polishing jig according to this embodiment does not lose elasticity even when the seal member 34 is compressed in the annular groove 41, so that high sealing performance can be obtained. In addition, the seal member 34 can be prevented from being worn when the polishing jig 2 is attached or detached.

The reason why the high sealing performance is obtained is that the sealing member 34 is pressed against each wall 42 to 44 of the annular groove 41 and the wall surface 16a of the air inlet 16 with an appropriate elasticity. That is, since the sealing member 34 can be deformed so as to follow the minute irregularities formed on the surfaces of these walls, the sealing performance is improved.
The reason why the wear of the seal member 34 can be prevented is that the seal member 34 is not pressed against the wall surface 16a of the air inlet 16 with an excessive force, and the frictional resistance when sliding against the wall surface 16a is relatively. This is because it becomes smaller.

  Further, in the air injection device 1 for the polishing jig according to this embodiment, since the seal member 34 is inserted into the annular groove 41 and does not come off from the inlet member 4, the polishing jig 2 is installed after the air is injected. The operation of loading the polishing apparatus from 3 is not interrupted. For this reason, by using this air injection device 1, it becomes possible to polish the spectacle lens efficiently.

(Second Embodiment)
The inlet member and the seal member can be formed as shown in FIGS. 5 and 6, the same or equivalent members as those described with reference to FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

  The outer diameter d2 of the seal member 34 shown in FIG. 5 is formed larger than the inner diameter B of the air inlet 16 in the same manner as the seal member 34 shown in FIGS. However, the thickness W of the seal member 34 is formed so as to coincide with the groove width G (the distance between the first side wall 43 and the second side wall 44) G of the annular groove 41. The inner diameter d1 of the seal member 34 is formed larger than the outer diameter D of the peripheral wall 42 of the annular groove 41.

That is, in this embodiment, a gap S is formed between the peripheral wall 42 of the annular groove 41 and the inner peripheral portion of the seal member 34. The seal member 34 according to this embodiment is elastically deformed inward in the radial direction so as to enter the gap S as shown in FIG. 6 by being inserted into the air inlet 16. In this way, the gap S is sealed by the elastic deformation of the seal member 34.
Also in this embodiment, since the sealing member 34 does not lose its elasticity, the same effect as that obtained when the above-described embodiment is adopted can be obtained.

(Third embodiment)
The inlet member and the seal member can be formed as shown in FIGS. 7 and 8, the same or equivalent members as those described with reference to FIGS. 1 to 4 are denoted with the same reference numerals, and detailed description thereof is omitted as appropriate.

  The outer diameter d2 of the seal member 34 shown in FIG. 7 is formed larger than the inner diameter B of the air inlet 16 in the same manner as the seal member 34 shown in FIGS. Further, the thickness W of the seal member 34 is formed smaller than the groove width G of the annular groove 41 (the distance between the first side wall 43 and the second side wall 44). Further, the inner diameter d 1 of the seal member 34 is formed larger than the outer diameter D of the peripheral wall 42 of the annular groove 41.

  That is, in this embodiment, a gap S1 is formed between at least one of the first and second side walls 43, 44 of the annular groove 41 and the seal member 34, and the peripheral wall 42 and the seal are sealed. A gap S <b> 2 is formed between the inner peripheral portion of the member 34. When the seal member 34 according to this embodiment is inserted into the air inlet 16, the seal member 34 is pushed in the direction toward the second side wall 44 by contact with the wall surface 16 a of the air inlet 16, and is radially inward. It is pushed toward.

As a result, as shown in FIG. 8, the seal member 34 is elastically deformed toward the inner side in the radial direction so as to enter the gap S <b> 2 located on the inner side in the radial direction, and the axial direction so as to enter the other gap S <b> 1. It is elastically deformed. As the seal member 34 is elastically deformed in this manner, the gap S1 and the gap S2 are sealed.
Even in this embodiment, the elasticity is not lost despite the fact that the seal member 34 is compressed in the annular groove 41, so that the same effect as that obtained when the above-described embodiment is adopted can be obtained.

  The inlet member 4 shown in this embodiment has a size as shown in FIG. 9 and when air is actually injected into the polishing jig 2, it is repeated without air leaking or the seal member 34 falling off. Could be used. The outer diameter A of the main body 33 of the inlet member 4 used in this experiment is 12.6 mm, the outer diameter D of the peripheral wall 42 of the annular groove 41 is 7.2 mm, and the groove width G is 3.7 mm. The seal member 34 has an inner diameter d1 of 7.5 mm and a thickness W of 3.55 mm. For this reason, the outer diameter of the sealing member 34 is 14.6 mm. The seal member 34 used was an O-ring called type AS568-203. The material of this O-ring is fluororubber (FPM).

  In this experiment, a plurality of polishing jigs 2 that were actually polished were used, and attachment / detachment and air injection were performed 100 times for each polishing jig 2. During the experiment, the presence or absence of the seal member 34 was confirmed when the polishing jig 2 was attached or detached, and the presence or absence of air leakage was confirmed during air injection. As a result of the experiment, when the number of times that the polishing jig 2 can be attached / detached without detaching the seal member 34 is 95 times or more, the attachment / detachment is passed, and the number of times that air can be injected without leaking air is 95 times or more. Was acceptable for air injection.

  As a result of this experiment, as shown in FIG. 10, in all the polishing jigs 2, the attachment / detachment of the polishing jig and the air injection were acceptable. In FIG. 10, the pass for each polishing jig 2 is indicated by ○. The A size and B size of each polishing jig 2 shown in FIG. 10 are values obtained by measuring the inner diameter B of the air inlet 16 from two directions orthogonal to each other. As can be seen from FIG. 10, the inner diameter B of the air inlet 16 of the polishing jig 2 used in this experiment is 14.0 to 14.32 mm. The size of the air inlet 16 differs for each polishing jig 2 because of the tolerance.

  When the inventor repeatedly used the inlet member 4 used in the above-described experiment and the conventional inlet member for comparison and repeated injection of air, the effect of the present invention was verified as follows. did it. In the following, the inlet member 4 used in the experiment is referred to as “the product of the present invention”, and the conventional inlet member is referred to as the “conventional product”. In the verification of this effect, it is avoided to repeatedly use only a specific polishing jig assuming the state of the actual polishing process, and all the plurality of polishing jigs 2 used in the actual polishing process are verified. Used to be the target.

(1) Frequency of injection work mistakes:
In the conventional product, the seal member may come off, and out of 100 injection operations, an injection operation error occurred 5 times. That is, the frequency of mistakes in the conventional product is 5%.
The product of the present invention had one injection operation error out of 100 injection operations. In other words, the frequency of injection work mistakes for the product of the present invention is 1%.
(2) Workability of attachment / detachment work:
The conventional product is a so-called cover type seal member, so that it is easy to come off and the workability of the attaching / detaching work is low.
The product of the present invention does not come off because the seal member is of a so-called fitting type, and has high workability for attaching and detaching operations.
(3) Exchange frequency:
The replacement frequency of the conventional product is about twice per month (30 days) when the injection operation is performed 100 times a day. In other words, the conventional product needs to be replaced twice while the injection operation is performed 3000 times.
The replacement frequency of the product of the present invention is about once every two months (60 days) when the injection operation is performed 100 times a day. That is, the product of the present invention can inject air 6000 times with one exchange.
(4) Durability:
The durability of the conventional product and the durability of the product of the present invention were equivalent.
(5) Cost (unit price):
The conventional product is 3590 yen per piece, and the product of the present invention is 200 yen per piece.
(6) Monthly running cost (estimated):
The running cost of the conventional product is 7180 yen per month if the replacement frequency of the conventional product is twice per month.
The running cost of the product of the present invention is 100 yen per month when the replacement frequency of the product of the present invention is 0.5.
(7) Other:
Since the conventional product is a so-called processed product, the time required for manufacturing is relatively long.
Since the product of the present invention can be manufactured using a general-purpose O-ring, the time required for manufacturing is remarkably shortened compared to the conventional product.

  In each of the above-described embodiments, an example in which an O-ring having a circular cross section is used as the seal member 34 has been described. However, the cross-sectional shape of the seal member 34 can be changed as appropriate, such as an oval or an oval.

  DESCRIPTION OF SYMBOLS 1 ... Polishing jig | tool air injection apparatus, 2 ... Polishing jig | tool, 3 ... Installation stand, 3a ... Installation surface, 4 ... Injection port member, 6 ... Air supply apparatus, 12a ... Mounting surface, 16 ... Air injection port, 33 DESCRIPTION OF SYMBOLS ... Main body, 36 ... Air outlet, 34 ... Seal member, 41 ... Circular groove, 42 ... Peripheral wall, 43 ... 1st side wall, 44 ... 2nd side wall, S, S1, S2 ... Gap.

Claims (4)

An inlet member to be inserted into an air inlet of an eyeglass lens polishing jig having a balloon member that is inflated by air pressure;
A polishing jig installation base having an installation surface on which the spectacle lens polishing jig is placed and supporting the inlet member in a state of protruding from the installation surface;
An air supply device for discharging air from an air outlet formed at the protruding side end of the inlet member;
The air inlet is opened so that the opening shape is circular on the mounting surface facing the installation surface in the spectacle lens polishing jig,
The inlet member is formed in a columnar shape and has a main body having an air passage connected to the air outlet;
A seal member mounted on the outer periphery of the main body,
An annular groove having a peripheral wall parallel to the outer peripheral surface of the main body and a pair of side walls extending radially outward from the peripheral wall is formed on the outer peripheral portion of the main body,
The seal member is formed into an annular shape extending in the entire circumferential direction along the annular groove by an elastic body, and is inserted into the annular groove.
The outer diameter of the seal member is formed larger than the inner diameter of the air inlet,
A polishing jig characterized in that a gap that is sealed by a sealing member that is elastically deformed by inserting an inlet member into the air inlet is formed between the sealing member and the annular groove. Air injection device.   The air injection device for a polishing jig according to claim 1, wherein the gap is formed between the side wall of the annular groove and the seal member.   3. The air for polishing jig according to claim 1, wherein the gap is formed between the peripheral wall of the annular groove and the seal member. 4. Injection device.   4. The polishing jig air injection apparatus according to claim 1, wherein the seal member is formed of an O-ring. 5.

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