An oil-immersed inverted current transformer pouring tool and a pouring method thereof

Abstract

The application provides an oil-immersed inverted current transformer pouring tool and a pouring method, and relates to the field of oil-immersed inverted current transformer pouring. The tool comprises a supporting seat, a pressing plate is arranged on the upper part of the supporting seat, a pull rod is detachably arranged on the pressing plate, a positioning disc is movably arranged on the pull rod, supporting blocks are evenly arranged on the outer circumferential surface of the positioning disc, the diameter of the positioning disc is smaller than the inner hole diameter of the current transformer supporting seat, a locking assembly is detachably arranged on the pull rod, the locking assembly can abut against the positioning disc, the locking assembly can drive the pull rod to move upward, a pouring disc is detachably arranged on the pull rod, the pouring disc is arranged on the upper part of the positioning disc, the pouring disc can move upward and downward along the pull rod, and the pouring disc is provided with a pouring hole. The current transformer supporting seat, the porcelain sleeve and the oil storage tank can be pre-connected into an integral whole before pouring, the generation of pouring bubbles is reduced, the generation of pouring cracks is reduced, and the pouring quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pouring manufacturing of oil-immersed inverted current transformers, and particularly relates to a pouring tool and a pouring method for an oil-immersed inverted current transformer. BACKGROUND

[0002] As high-voltage power transformation equipment commonly used in power system substations, a current transformer is one of the main electrical equipment in a substation, and mainly provides secondary current for protection and measurement. The primary side of the current transformer is connected with primary high-voltage equipment, and the secondary side is connected with secondary equipment. The current transformer not only effectively isolates secondary electrical equipment such as measuring instruments and relays from high-voltage electrical devices to ensure the safety of workers, but also standardizes and miniaturizes measuring instruments and relays, and can use small cross-section wires and cables for long-distance measurement. When a high-voltage side is disconnected, the current transformer can also protect the current coil of the measuring instrument from being damaged by a large current. At present, current transformers are mainly divided into oil-immersed upright current transformers, oil-immersed inverted current transformers, and SF6 gas insulated inverted current transformers. Among them, the oil-immersed inverted current transformer is connected between the support, the porcelain sleeve, and the oil storage tank by using cement pouring technology. The cement pouring can ensure the mechanical reliability of the connection between the three.

[0003] In the existing pouring process of the oil-immersed inverted current transformer, the oil storage tank is placed on the support seat and fixed by using a press iron. Then, the porcelain sleeve and the current transformer support are stacked in sequence. Then, cement is poured from the current transformer support to realize the pouring connection of the three.

[0004] However, by using this pouring method, the current transformer support, the porcelain sleeve, and the oil storage tank are only stacked together by gravity, and it is difficult to ensure that the three have a large pressure therebetween. This can easily cause uneven gaps and poor adhesion between the three, air enters from the gaps, and pouring bubbles and pouring cracks are generated, which affects the safe and reliable operation of the product. SUMMARY

[0005] In order to overcome the problems of pouring cracks and poor pouring quality of the current transformer support, the porcelain sleeve, and the oil storage tank in the prior art, the present application provides a pouring tool and a pouring method for an oil-immersed inverted current transformer, which can reduce the generation of pouring bubbles and thus reduce pouring cracks and improve pouring quality.

[0006] The technical scheme adopted by the present application to solve the above technical problems is: an oil-immersed inverted current transformer pouring tool, comprising a supporting seat, a pressing plate is arranged on the upper portion of the supporting seat, the diameter of the pressing plate is larger than the inner diameter of the connecting portion of the oil conservator and the porcelain sleeve, a pull rod is detachably arranged on the pressing plate, a positioning disc is movably arranged on the pull rod, supporting blocks are uniformly arranged on the outer circumferential surface of the positioning disc, the diameter of the positioning disc is smaller than the inner hole diameter of the current transformer support, a locking assembly is detachably arranged on the pull rod, the locking assembly can abut against the positioning disc, the locking assembly can drive the pull rod to move upward, a pouring disc is detachably arranged on the pull rod, the pouring disc is located on the upper portion of the positioning disc, the pouring disc can move up and down along the pull rod, a pouring hole is arranged on the pouring disc, and the pouring hole is opposite to the gap between the positioning disc and the current transformer support. Through the action of the pressing plate, the pull rod, the positioning disc and the locking assembly, the current transformer support, the porcelain sleeve and the oil conservator can be pre-connected as a whole before pouring, the gaps between the three are uniform and tight, a large pressure exists between the three, air is prevented from entering the gaps between the three to generate air bubbles during pouring, cracks are avoided, and the pouring quality is affected.

[0007] Further, guiding columns are symmetrically arranged on the supporting seat, the pressing plate is movably sleeved on the guiding columns, the pressing plate is coaxially arranged with the supporting seat, and the pull rod is threadedly connected with the pressing plate. Through the guiding columns, the pressing plate can be prevented from moving horizontally under the action of external force, and the pull rod is inconvenient to connect.

[0008] Further, supporting seat connecting holes are arranged on the supporting blocks, and connecting bolts are arranged in the supporting seat connecting holes. Through the connecting bolts, the positioning disc and the current transformer support can be connected as a whole, the positioning disc can be prevented from moving during abutment with the locking assembly, the force applied to the current transformer support is prevented from being uneven, and the quality of pre-connection of the three is affected.

[0009] Further, a jam nut is arranged on the locking assembly, external threads are arranged on the corresponding positions of the pull rod, and the thread rotation direction of the jam nut is the same as that of the threads on the pressing plate. The jam nut is used to lift the pull rod and press the positioning disc, the installation is convenient, the pouring efficiency is improved, the jam nut has a pre-tightening function, and the loosening is effectively prevented.

[0010] Further, the locking assembly comprises a locking sleeve and an adjusting washer, both of which are sleeved on the pull rod, an inner thread is arranged on the upper end of the inner wall of the locking sleeve, the rotation direction of the inner thread is the same as that of the thread on the pressing plate, an outer thread is correspondingly arranged on the upper end of the pull rod, and the two end faces of the adjusting washer are respectively abutted against the locking sleeve and the positioning disc. Since current transformers of different types have different heights, the lengths of the corresponding pull rods are also different, and the cooperation of the locking sleeve and the adjusting washer can adapt to pull rods of various lengths.

[0011] Further, the locking sleeve is of a segmented structure. The segmented structure realizes modular design of the locking sleeve, expands the length range of the pull rod matched with the given number of locking sleeves, and further improves the application range of the tooling.

[0012] Further, a vibration table is further included, and the support seat is arranged on the vibration table. The vibration table can accelerate the flow speed and uniformity of the cement, and improve the pouring efficiency and quality.

[0013] Further, an oil tank pressing iron is further included, and one end of the oil tank pressing iron is detachably mounted on the vibration table. The oil tank is fixed through the oil tank pressing iron.

[0014] The application further provides a pouring method for the oil-immersed inverted current transformer, and the pouring method comprises the following steps:

[0015] S01: The oil tank is sleeved on the support seat in a coaxial state, and the oil tank pressing iron is pressed on the oil tank;

[0016] S02: The pull rod is inserted into the oil tank and connected with the pressing plate;

[0017] S03: The porcelain sleeve is hung, and the porcelain sleeve is hung directly above the oil tank;

[0018] S04: The current transformer support is hung, and the current transformer support is placed directly above the porcelain sleeve;

[0019] S05: The positioning disc is connected with the current transformer support;

[0020] S06: The locking assembly is abutted against and locked with the positioning disc, so that the current transformer support, the porcelain sleeve and the oil tank are pre-connected as a whole.

[0021] S07: The pouring cement is adjusted according to the proportion;

[0022] S08: The pouring disc is sleeved on the pull rod and moved to the upper part of the positioning disc;

[0023] S09: The vibration table is opened, and the pouring cement is injected from the pouring hole on one side.

[0024] S10: After pouring and solidifying, transfer to an incubator for curing.

[0025] Further, in the S06, according to the length of the pull rod, the corresponding adjusting washer and locking sleeve are selected, and then the adjusting washer and the locking sleeve are sequentially sleeved, and the locking sleeve is rotated until abutting against the adjusting washer.

[0026] From the above technical solutions, the present application has the following advantages:

[0027] The present application provides a pouring tool and pouring method for oil-immersed inverted current transformers, which can pre-connect the current transformer support, porcelain sleeve and oil storage tank into a whole before pouring through the action of the pressing plate, pull rod, positioning disc and locking assembly, the gaps between the three are uniform and tight, ensuring that there is a large pressure between the three, avoiding air entering the gaps between the three during pouring to generate bubbles, causing cracks and affecting the pouring quality; the guide column can prevent the pressing plate from being displaced horizontally under the action of external force and being inconvenient to connect with the pull rod; the connecting bolt can connect the positioning disc and the current transformer support into a whole, preventing the positioning disc from being displaced during abutting against the locking assembly and affecting the quality of the pre-connection of the three; the jacking nut can lift the pull rod and press the positioning disc, which is convenient to install and has a pre-tightening function to effectively prevent loosening; the locking sleeve and adjusting washer can be matched with pull rods of various lengths; the modular design of the locking sleeve is realized through the segmented structure, which expands the length range of the pull rods matched with the given number of locking sleeves and further improves the application range of the tool; the vibration table can accelerate the flow speed and uniformity of the cement and improve the pouring efficiency and quality. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the description, and obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 It is a schematic view of the assembly structure of the current transformer support, porcelain sleeve and oil storage tank in the first embodiment of the present application.

[0030] Figure 2 It is a schematic view of the structure of the positioning disc in the first embodiment of the present application.

[0031] Figure 3 It is a schematic view of the structure of the pouring disc in the first embodiment of the present application.

[0032] Figure 4 Figure 2 is a schematic view of the assembly structure of the oil conservator, porcelain sleeve and current transformer support according to the second embodiment of the present application.

[0033] Figure 5 For Figure 4 the enlarged view at A in the middle.

[0034] In the figure, 1 is a vibration table, 2 is an oil conservator, 3 is a support seat, 4 is a guide column, 5 is a pressing plate, 6 is a porcelain sleeve, 7 is a current transformer support, 8 is a positioning disc, 801 is a support block, 802 is a support connecting hole, 803 is a pull rod mounting hole, 9 is a counter-nut, 10 is a pull rod, 11 is an adjusting grommet, 12 is a locking sleeve, 13 is a pouring disc, 1301 is a pouring hole, and 14 is an oil conservator pressing iron. DETAILED DESCRIPTION

[0035] In order to make the objectives, characteristics and advantages of the present application more obvious and easy to understand, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the specific embodiments. Obviously, the embodiments described below are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present patent, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present patent.

[0036] The inventor found that in the existing pouring process of the oil-immersed inverted current transformer, the current transformer support, porcelain sleeve and oil conservator are simply stacked together by gravity, which cannot guarantee a large pressure between the three, and is prone to cause uneven and non-tight gaps between the three, air enters the gaps, generates pouring bubbles and causes pouring cracks. Based on this, in an embodiment of the present application provided by the inventor, the current transformer support, porcelain sleeve and oil conservator are pre-connected into a whole by a pouring tool before pouring, have a large force between each other, guarantee uniform and tight gaps between the three, and solve the problems of generating pouring bubbles, causing pouring cracks and poor pouring quality in the prior art. DETAILED DESCRIPTION

[0038] As Figures 1 to 3As shown, the specific embodiment provides an oil-immersed inverted current transformer pouring tool, which comprises a pouring disc 13, a support seat 3, a pressing plate 5, a pull rod 10, a locking assembly, a positioning disc 8, a vibrating table 1 and an oil tank pressing iron 14. The upper part of the support seat 3 is provided with the pressing plate 5, the diameter of the pressing plate 5 is greater than the inner diameter of the connecting part of the oil tank 2 and the porcelain sleeve 6, the pressing plate 5 can abut against the inside of the oil tank pressing iron 14, and the pull rod 10 is detachably arranged on the pressing plate 5. The detachable connection can be realized through threaded cooperation or cooperation of spring pins and clamping grooves. In the specific embodiment, the connection is realized through threads. The positioning disc 8 is provided with a pull rod mounting hole 803 and can move up and down along the pull rod 10. The outer circumferential surface of the positioning disc 8 is uniformly provided with support blocks 801, which can be placed on the current transformer support 7 to realize support. The diameter of the positioning disc 8 is smaller than the inner hole diameter of the current transformer support 7, so as to form a channel for cement flow. The pull rod 10 is detachably provided with a locking assembly, which can abut against the positioning disc 8 and drive the pull rod 10 to move upward. The pull rod 10 is also detachably provided with a pouring disc. The pouring disc 13 is provided with a through hole and can move up and down along the pull rod 10. The pouring disc is located at the upper part of the positioning disc 8. The pouring disc 13 is provided with a pouring hole 1301. After installation, the pouring hole 1301 avoids the position of the support block 801. The pouring hole 1301 is opposite to the gap between the positioning disc 8 and the current transformer support 7. In the specific embodiment, the pouring hole 1301 is an arc-shaped hole provided with two corresponding central angles of 100°-120°. One of the pouring holes is used for pouring, and the other is used for communicating with air to discharge internal gas. Through the action of the pressing plate 5, the pull rod 10, the positioning disc 8 and the locking assembly, the current transformer support 7, the porcelain sleeve 6 and the oil tank 2 can be pre-connected as a whole before pouring. The gaps between the three are uniform and tight, which ensures that there is a large pressure between the three, avoids air entering from the gaps between the three to produce bubbles during pouring, causes cracks and affects the pouring quality. The support seat 3 is arranged on the vibrating table 1 through bolts or clamping groove block assemblies. The vibrating table 1 can accelerate the cement flow speed and uniformity, improve the pouring efficiency and quality. The oil tank pressing iron 14 is installed on the vibrating table 1 through bolts.

[0039] As shown, Figure 1 In order to facilitate the connection of the pull rod 10 and the pressing plate 5, the support seat 3 is symmetrically provided with guide columns 4. The guide columns 4 are provided with limiting bosses. The pressing plate 5 is provided with guide holes. The guide holes are clearance-fitted with the guide columns 4. The central position of the pressing plate 5 is provided with a threaded mounting hole, which is used for installing the pull rod 10. The threaded mounting hole is coaxially arranged with the support seat 3.

[0040] As shown, Figure 1 and Figure 2As shown, in order to prevent the positioning disk 8 from shifting during the contact with the locking component, a support connection hole 802 is provided on the support block 801. The support connection hole 802 is provided with a connecting bolt, which can connect the positioning disk 8 to the current transformer support 7.

[0041] like Figure 1 As shown, in order to lift the pull rod 10 and abut against the positioning plate 8, the locking assembly uses a top nut 9. The pull rod 10 has an external thread at the corresponding position, and the thread direction of the top nut 9 is the same as that of the thread on the pressure plate 5. The top nut 9 is used to lift the pull rod 10 and press the positioning plate 8, which is convenient to install and helps to improve the pouring efficiency. At the same time, the top nut 9 has a pre-tightening function to effectively prevent loosening. Specific Implementation Method Two

[0043] like Figure 4 As shown, this specific embodiment provides a casting fixture for an oil-immersed inverted current transformer. Its structure is basically the same as that of Specific Embodiment One, except that the locking assembly includes a locking sleeve 12 and an adjusting washer 11. Both the locking sleeve 12 and the adjusting washer 11 are sleeved on the pull rod 10. The upper end of the inner wall of the locking sleeve 12 is provided with an internal thread, the direction of which is the same as the direction of the thread on the pressure plate 5. Correspondingly, the upper end of the pull rod 10 is provided with an external thread. The locking sleeve 12 is sleeved on the outer circumference of the pull rod 10. The two end faces of the adjusting washer 11 abut against the locking sleeve 12 and the positioning plate 8, respectively. The locking sleeve 12... The adjustment washer 11 can be used to accommodate pull rods 10 of various lengths. When the length of the pull rod 10 increases, the threaded part at the upper end does not increase. The original locking sleeve 12 cannot abut against the positioning plate 8 after it is installed. By adding an adjustment washer 11 of appropriate height between the locking sleeve 12 and the positioning plate 8, the positioning plate 8 can be pressed and the pull rod 10 can be continuously lifted. Through this technical solution, pull rods 10 of various lengths can be machined with a fixed length of external thread at the end where the locking sleeve 12 is installed. Pull rods 10 of different lengths do not need to be distinguished during processing, thus improving the manufacturing efficiency of this tooling.

[0044] like Figure 5As shown, in order to further expand the range of adaptation to different lengths of pull rod 10, locking sleeve 12 is of segmented structure; through the segmented structure, the modular design of locking sleeve 12 is realized, various combinations can be realized, compared with the integral structure of locking sleeve 12, the length range of pull rod 10 matched with the number of locking sleeve 12 is expanded, the application range of the tooling is further improved, for example: there are two locking sleeves 12, which are segmented into three segments, each segment has different length, through permutation and combination, 10 combination forms can be generated to match 10 lengths of pull rod (each combination must have a segment with internal thread), compared with the integral structure, the segmented structure greatly expands the application range of the given number of locking sleeves 12, greatly reduces the number of spare parts, and is convenient for management. THIRD EMBODIMENT

[0046] The embodiment provides a pouring method of an oil-immersed inverted current transformer, and the pouring tooling of the oil-immersed inverted current transformer in the second embodiment is used, and the method comprises the following steps:

[0047] S01: The oil storage tank is coaxially sleeved on the support seat, and the oil storage tank is pressed on the oil storage tank by the press iron;

[0048] S02: The pull rod is inserted into the oil storage tank and connected with the pressing plate;

[0049] S03: The porcelain sleeve is hung, and the porcelain sleeve is hung directly above the oil storage tank;

[0050] S04: The current transformer support is hung, and the current transformer support is placed directly above the porcelain sleeve;

[0051] S05: The positioning disc is connected with the current transformer support;

[0052] S06: The locking assembly is abutted and locked with the positioning disc, so that the current transformer support, the porcelain sleeve and the oil storage tank are pre-connected as a whole.

[0053] S07: The pouring cement is adjusted according to the proportion;

[0054] S08: The pouring disc is sleeved on the pull rod and moved to the upper part of the positioning disc;

[0055] S09: The vibration table is opened, and the pouring cement is injected from the pouring hole on one side;

[0056] S10: After the pouring is solidified, the constant temperature box is turned to carry out maintenance.

[0057] In S06, according to the length of the pull rod, the appropriate adjusting washer and locking sleeve are selected, and then the adjusting washer and the locking sleeve are sleeved in turn, and the locking sleeve is rotated until it abuts with the adjusting washer.

[0058] From the above specific embodiments, the present application has the following beneficial effects:

[0059] 1. The current transformer support 7, the porcelain sleeve 6 and the oil conservator 2 can be pre-connected as a whole before pouring by the action of the pressing plate 5, the pull rod 10, the positioning disc 8 and the locking assembly, the gaps between the three are uniform and tight, and a large pressure exists between the three, so that air does not enter the gaps between the three to produce bubbles during pouring, cracks are avoided, and the pouring quality is ensured;

[0060] 2. The pressing plate 5 can be prevented from being displaced horizontally under the action of external force by the guide column 4, and is inconvenient to be connected with the pull rod 10;

[0061] 3. The positioning disc 8 and the current transformer support 7 can be connected as a whole by the connecting bolt, so that the positioning disc 8 is prevented from being displaced during abutting with the locking assembly, and the quality of pre-connection of the three is affected;

[0062] 4. The pull rod 10 is lifted and the positioning disc 8 is pressed tightly by the jacking nut 9, installation is convenient, and the jacking nut 9 has a pre-tightening function, so that loosening is effectively prevented;

[0063] 5. The locking sleeve 12 and the adjusting grommet 11 can be matched to adapt to pull rods 10 of various lengths;

[0064] 6. The modular design of the locking sleeve 12 is realized by the sectional structure, the length range of the pull rod 10 matched with the number of the locking sleeve 12 is expanded, and the application range of the tooling is further improved;

[0065] 7. The vibration table 1 can accelerate the flow speed and uniformity of cement, and improve the pouring efficiency and quality.

[0066] The terms "upper", "lower", "outer", "inner", and the like (if any) in the specification and claims of the application and the above-described drawings are used to distinguish relative positions, and do not necessarily give a qualitative meaning. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0067] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An oil-immersed inverted current transformer pouring tool, comprising a supporting seat (3), characterized in that, The upper portion of the support base (3) is provided with a pressing plate (5), the diameter of the pressing plate (5) is greater than the inner diameter of the connection part of the oil conservator and the porcelain sleeve, a pull rod (10) is detachably arranged on the pressing plate (5), a positioning disc (8) is movably arranged on the pull rod (10), a plurality of support blocks (801) are uniformly arranged on the outer circumferential surface of the positioning disc (8), the diameter of the positioning disc (8) is less than the inner hole diameter of the current transformer support, a locking assembly is detachably arranged on the pull rod (10), the locking assembly can abut against the positioning disc (8), the locking assembly can drive the pull rod (10) to move upward, a pouring disc (13) is also detachably arranged on the pull rod (10), the pouring disc (13) is located on the upper portion of the positioning disc (8), the pouring disc (13) can move up and down along the pull rod (10), the pouring disc (13) is provided with a pouring hole (1301), the pouring hole (1301) is opposite to the gap between the positioning disc (8) and the current transformer support; The support base (3) is symmetrically provided with guide columns (4), the pressing plate (5) is movably sleeved on the guide columns (4), the pressing plate (5) is coaxially arranged with the support base (3), and the pull rod (10) is threadedly connected with the pressing plate (5); The locking assembly comprises a locking sleeve (12) and an adjusting grommet (11), the locking sleeve (12) and the adjusting grommet (11) are both sleeved on the pull rod (10), the inner wall of the locking sleeve (12) is provided with an internal thread at the upper end, the rotation direction of the internal thread is the same as that of the thread on the pressing plate (5), the upper end of the pull rod (10) is correspondingly provided with an external thread, and the two end faces of the adjusting grommet (11) respectively abut against the locking sleeve (12) and the positioning disc (8); The locking sleeve (12) is of a sectional structure.

2. The oil-filled inverted current transformer potting tooling of claim 1, wherein, The support blocks (801) are provided with support connection holes (802), and the support connection holes (802) are provided with connecting bolts.

3. The oil-filled inverted current transformer potting tooling of claim 2, wherein, Further comprising a vibrating table (1), and the support base (3) is arranged on the vibrating table (1).

4. The oil-filled inverted current transformer potting tooling of claim 3, wherein, Further comprising an oil conservator pressing iron (14), one end of the oil conservator pressing iron (14) is detachably mounted on the vibrating table (1).

5. A method of potting an oil-immersed inverted current transformer, characterized by The oil-immersed inverted current transformer pouring tool comprises the following steps: S01: The oil conservator is coaxially sleeved on the support base, and the oil conservator pressing iron is pressed on the oil conservator; S02: The pull rod is inserted into the oil conservator and connected with the pressing plate; S03: The porcelain sleeve is hoisted and placed above the oil conservator; S04: The current transformer support is hoisted and placed above the porcelain sleeve; S05: The positioning disc is connected with the current transformer support; S06: The locking assembly is abutted and locked with the positioning disc, so that the current transformer support, the porcelain sleeve and the oil conservator are pre-connected as a whole; S07: The pouring cement is adjusted according to the proportion; S08: The pouring disc is sleeved on the pull rod and moved to the upper portion of the positioning disc; S09: The vibrating table is turned on, and the pouring cement is poured from the pouring hole on one side; S10: After the pouring is solidified, the constant temperature box is used for curing.

6. The oil-filled inverting current transformer potting method as claimed in claim 5, characterized by, In S06, according to the length of the pull rod, the corresponding adjusting grommet and locking sleeve are selected, and then the adjusting grommet and the locking sleeve are sequentially sleeved, and the locking sleeve is rotated until it abuts against the adjusting grommet.

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