CN219819603U - Self-centering net plug rod - Google Patents

Abstract

The utility model discloses a self-centering net-placing stopper rod, which comprises a movable core rod, a core rod guide sleeve and a jaw mechanism, wherein the tail end of the movable core rod is provided with a conical push head; inserting the conical push head into the jaw mechanism, and enabling the movable jaw to extend out of the mandrel guide sleeve in the radial direction under the downward pressure of the conical push head so as to adjust the radial dimension of the mandrel guide sleeve; when the conical push head is separated from the movable claw, the movable claw is retracted and reset through the elastic reset mechanism, and the initial state is restored. By using the structure, the radial size can be adjusted by extending and retracting the movable claw, so that even if the gap between the stopper rod and the inner wall of the copper pipe is too large, the stopper rod is more convenient to be inserted into the copper pipe, and the insertion is flexible. The radial size of the tail end of the stopper rod is adjusted by moving the clamping jaw, so that the stopper rod can adapt to heat pipes with different inner diameters, and the adaptation size is wider.

Description

Self-centering net plug rod

Technical Field

The utility model relates to the field of heat pipe production equipment, in particular to a self-centering net stopper rod.

Background

The heat pipe is a heat transfer element with high heat conducting performance, and has extremely high heat conducting performance by evaporating and condensing working medium in the totally-enclosed vacuum tube shell. Along with the development of thinning of the heat pipe, the capillary structure inside the heat pipe increasingly adopts a copper net, as shown in fig. 1, in the process of putting the copper net 3 into the copper pipe 2, the copper net 3 needs to be plugged into the copper pipe 2 by a plug rod 1, the plug rod 1 is a single flat rod, and is processed into a size matched with the inner wall of the copper pipe 2, at this time, due to the change in tolerance ranges of the outer diameter, the wall thickness, the ellipticity and the like of the copper pipe, the following three problems are easy to occur:

1. when the ovality of the copper pipe is large or the external diameter is smaller, the stopper rod cannot be plugged in, and is blocked, the stopper rod cannot be made small, but after the stopper rod is made small, when the external diameter of the copper pipe is larger or the ovality is good, the gap between the stopper rod and the copper pipe is enlarged, and the copper net can be blocked in the gap between the stopper rod and the inner wall of the copper pipe, so that the copper net cannot be plugged in.

2. In order to easily put the stopper into the copper pipe, the head of the stopper is usually rounded, the copper net is easily expanded when the copper net is jacked, and the copper net card is inserted into a gap between the copper pipe and the stopper.

3. The stopper rod is generally made into a 1 shape, and theoretically, the two sides of the end part of the stopper rod are in balance contact with the copper net, but the stopper rod is manually placed, because a gap is reserved between the stopper rod and the stopper rod, absolute centering is difficult to ensure, once one side of the stopper rod contacts with the copper net, stress eccentricity of the copper net can be caused, the copper net can be sunken into the middle, the copper net is deformed or blocked, and the heat pipe is scrapped.

Disclosure of Invention

Aiming at the problems, the main purpose of the utility model is to provide a self-centering net-placing stopper rod, which aims to adjust the radial dimension to adapt to copper pipes with different inner diameters, easily insert the copper pipes into the copper pipes, balance the force applied to the copper net and realize the propelling of the copper net.

The utility model provides a self-centering net-placing stopper rod, which comprises a movable core rod and a core rod guide sleeve, wherein the movable core rod is movably arranged in the core rod guide sleeve and can move in the axial direction of the core rod guide sleeve; the tail end of the movable core rod is provided with a conical push head, the tail end of the core rod guide sleeve is provided with a jaw mechanism, the jaw mechanism comprises a plurality of movable jaws and an elastic reset mechanism, the movable jaws are circumferentially arranged around the core rod guide sleeve and are radially arranged along the core rod guide sleeve, the outer ends of the movable jaws face the radial outer side of the core rod guide sleeve, the inner ends of the movable jaws are close to the central axis direction of the core rod guide sleeve, and the movable jaws are movably installed and can radially move along the core rod guide sleeve; the radial outer wall of the conical push head is an inclined push surface corresponding to the movable claw, the movable claw moves into the claw mechanism through the conical push head, the inclined push surface is in contact with the inner end of the movable claw and radially pushes the movable claw along with continuous insertion of the conical push head, so that the movable claw extends out of the core rod guide sleeve in the radial direction; when the conical push head is separated from the movable claw, the movable claw is retracted and reset through the elastic reset mechanism.

Preferably, the inner end of the moving claw is provided with an inclined surface corresponding to the inclined direction of the inclined pushing surface.

Preferably, the elastic reset mechanism comprises a reset spring and a spring contact surface, wherein the reset spring is arranged in parallel with the moving direction of the moving claw, the spring contact surface is arranged on the moving claw and used for driving the reset spring to generate elasticity, one end of the reset spring is fixed, and when the moving claw stretches out to the radial outer side of the mandrel guide sleeve, the spring contact surface follows the moving claw to move towards the fixed end of the reset spring so as to squeeze the reset spring to generate elasticity or move away from the fixed end of the reset spring so as to stretch the reset spring to generate elasticity.

Preferably, the jaw mechanism further comprises a mounting main body connected to the tail end of the mandrel guide sleeve, and a plurality of jaw mounting grooves which are formed in the mounting main body and are matched with the movable jaws, wherein the mounting main body is communicated with the tail end of the mandrel guide sleeve, and the conical push head extends into the mounting main body; the claw mounting groove is arranged along the radial direction of the core rod guide sleeve, the claw mounting groove is opened towards the radial outer side of the core rod guide sleeve, and the movable claw is movably mounted in the claw mounting groove.

Preferably, the inner cavity of the installation main body is hollow, and the claw installation grooves are mutually communicated.

Preferably, a spring mounting groove formed by recessing is provided on the bottom surface of the jaw mounting groove, and the return spring is mounted in the spring mounting groove.

Preferably, a spring corresponding groove is concavely arranged at a position of the movable claw opposite to the spring mounting groove, the spring contact surface is arranged in the spring corresponding groove, the spring mounting groove is opposite to the notch of the spring corresponding groove, the reset spring is arranged in the spring mounting groove and the spring corresponding groove, and the spring contact surface is in contact with the axial end surface of the reset spring.

Preferably, a positioning part is arranged in the spring mounting groove, and the positioning part is arranged at the fixed end of the return spring and is used for fixing the end of the return spring.

Preferably, the positioning portion extends into the spring corresponding groove opposite to an end of the spring corresponding groove.

Preferably, the number of the moving claws is 3, and the adjacent claws are uniformly spaced apart by 120 °.

Compared with the prior art, the utility model has the beneficial effects that:

the self-centering net-placing stopper rod comprises a movable core rod, a core rod guide sleeve and a claw mechanism, wherein the movable core rod is movably arranged in the core rod guide sleeve and can move in the axial direction of the core rod guide sleeve; the tail end of the movable core rod is provided with a conical push head, the jaw mechanism is arranged at the tail end of the core rod guide sleeve and comprises a plurality of movable jaws and an elastic reset mechanism, the movable jaws are circumferentially arranged around the core rod guide sleeve and are radially arranged along the core rod guide sleeve, the outer ends of the movable jaws face the radial outer side of the core rod guide sleeve, the inner ends of the movable jaws are close to the central axis direction of the core rod guide sleeve, and the movable jaws are movably arranged and can radially move along the core rod guide sleeve; the radial outer wall of the conical push head is an inclined push surface corresponding to the movable claw, when the movable core rod is inserted into the core rod guide sleeve towards the tail end of the movable core rod, the conical push head is inserted into the claw mechanism, the inclined push surface is in contact with the inner end of the movable claw and pushes the movable claw radially along with the continuous insertion of the conical push head, and the movable claw is opened under the downward pressure of the conical push head and extends out to the radial outer side of the core rod guide sleeve so as to adjust the radial size of the movable core rod; when the movable core rod moves reversely, the conical push head is separated from the movable claw, and the movable claw is retracted and reset through the elastic reset mechanism and returns to the initial state. By using the structure, the radial size can be adjusted by extending and retracting the movable claw, so that even if the size of the stopper rod is smaller than the inner diameter of the copper pipe, the gap between the stopper rod and the inner wall of the copper pipe is too large, the size of the stopper rod is set to be smaller than the inner diameter of the copper pipe, the stopper rod is more convenient to be inserted into the copper pipe, the insertion is flexible, the problem that the head part needs to be guided by a chamfer angle to cause the dead copper network card to be inserted into the guide gap is avoided.

Before inserting the copper pipe, keep initial state, make things convenient for the stopper stick to get into the copper pipe, after the stopper stick got into the copper pipe, push down movable plug with force and push out, contact the copper pipe inner wall with the removal jack catch, continue to go deep into the copper pipe with the stopper stick and go into the copper pipe to the removal jack catch with the tip contact of the copper net in the copper pipe, along with the promotion of stopper stick with the copper net push into the copper pipe in, after the copper net pushes in place, the movable plug is drawn back, the removal jack catch receives elastic restoring force and falls back to initial state of elasticity canceling release mechanical system this moment, make things convenient for the stopper stick to take out from the copper pipe.

The radial dimension of the tail end of the stopper rod is adjusted through the movable claw, so that the movable claw is ensured to be in contact with the inner wall of the copper pipe, and the problem that the gap between the inner wall of the copper pipe and the stopper rod is too large or too tight due to the change of the outer diameter and the wall thickness of the copper pipe or the deformation of the inner diameter caused by ovality and the like can be avoided.

The radial size of the tail end of the stopper rod is adjusted by moving the clamping jaw, so that the stopper rod can adapt to heat pipes with different inner diameters, and the adaptation size is wider.

The movable claw is provided with a plurality of movable claws, and the movable claw is circumferentially arranged around the mandrel guide sleeve, so that when the movable claw stretches out, the movable claw stretches out from the circumference of the stopper rod in a multi-direction manner to contact with the inner wall of the copper pipe, the stopper rod is ensured to be in a neutral position, and the self-centering effect is realized. The copper net is pushed into the copper pipe by the aid of the plurality of moving clamping jaws in a stretching and balancing mode, the stress of the copper net is balanced, and the problem that the copper net cannot be pushed in due to the fact that accurate centering cannot be conducted in the past to enable the copper net to incline, deform and be clamped into a gap is solved.

Drawings

Fig. 1 is a schematic diagram of a prior art stopper rod to stopper copper mesh into copper tubing as mentioned in the background.

Fig. 2 is a schematic structural view of a self-centering net stopper according to an embodiment of the present utility model.

Fig. 3 is an axial cross-sectional view of an initial state of a self-centering screen plug in an embodiment of the present utility model.

Fig. 4 is a cross-sectional view A-A of fig. 3.

Fig. 5 is an enlarged view of a portion C in fig. 3.

Fig. 6 is an axial cross-sectional view of a downward motion of a movable mandrel of a self-centering screen plug in an embodiment of the present utility model.

Fig. 7 is a sectional view of B-B in fig. 6.

Fig. 8 is an enlarged view of a portion D in fig. 6.

Fig. 9 is a schematic view of a self-centering screen plug applied to a copper pipe in an embodiment of the present utility model.

The achievement of the objects, functional features and advantages of the present utility model will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals identify like or similar elements or elements having like or similar functionality throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present utility model and should not be construed as limiting the utility model.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs; the terminology used in the description of the applications herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model; the terms "comprising" and "having" and any variations thereof in the description of the utility model and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion. The terms first, second and the like in the description and in the claims or in the above-described figures, are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the utility model. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

Referring to fig. 2 to 9, an embodiment of the present utility model provides a self-centering screen plug comprising a movable mandrel 2, a mandrel guide sleeve 1 and a jaw mechanism 3. The movable core rod 2 is movably mounted in the core rod guide sleeve 1 so as to be movable in the axial direction of the core rod guide sleeve 1, and as shown in fig. 3 and 6, the movable core rod 2 is inserted into the core rod guide sleeve 1 so as to be movable up and down in the axial direction thereof.

As shown in fig. 2, the end of the movable core rod 2 is provided with a tapered push head 21, the end of the core rod guide sleeve 1 is provided with a jaw mechanism 3, the jaw mechanism 3 comprises a plurality of movable jaws 31 and an elastic reset mechanism which are circumferentially arranged around the core rod guide sleeve 1, the movable jaws 31 are radially arranged along the core rod guide sleeve 1, the outer ends of the movable jaws 31 face the radial outer side of the core rod guide sleeve 1, and the inner ends of the movable jaws are close to the central axis direction of the core rod guide sleeve 1. The movable claw 31 is movably mounted and can move radially along the mandrel guide sleeve 1. The radially outer wall of the conical push head 21 is an inclined push surface corresponding to the movable claw 31, and the movable claw 31 is moved into the claw mechanism 3 by the conical push head 21, and the inclined push surface contacts with the inner end of the movable claw 31 and radially pushes the movable claw 31 along with the continuous insertion of the conical push head 21, so that the movable claw 31 protrudes to the radially outer side of the mandrel guide sleeve 1. When the tapered pusher 21 is disengaged from the moving claw 31, the moving claw 31 is retracted and restored by the elastic restoring mechanism.

As shown in fig. 2, the inner end of the moving claw 31 is provided with an inclined surface corresponding to the inclined direction of the inclined pushing surface, and is matched with the conical push head 21, so as to facilitate the insertion of the conical push head 21.

As shown in fig. 6, when the movable core rod 2 is inserted into the core rod guide sleeve 1 toward the distal end thereof, the tapered push head 21 is inserted into the click-dog mechanism 3, the inclined push surface contacts the inner end of the movable click-dog 31 and pushes the movable click-dog 31 radially with continued insertion of the tapered push head 21, the movable click-dog 31 expands by the downward pressure of the tapered push head 21, and protrudes radially outward of the core rod guide sleeve 1 to adjust the radial dimension thereof. When the movable core rod 2 moves reversely, the conical push head 21 is separated from the movable claw 31, the movable claw 31 is retracted and reset by the elastic reset mechanism, and the movable claw 31 is retracted to the initial state, as shown in fig. 3, which is a schematic diagram of the movable claw 31 being retracted to the initial state.

By using the structure, the radial size can be adjusted by extending and retracting the movable claw 31, so that even if the size of the stopper rod is smaller than the inner diameter of the copper pipe, the gap between the stopper rod and the inner wall of the copper pipe is too large, the size of the stopper rod is set to be smaller than the inner diameter of the copper pipe, the stopper rod is more convenient to be inserted into the copper pipe, the insertion is flexible, the problem that the head part needs to be guided by a chamfer angle to cause the dead copper network card to be inserted into the guide gap is avoided.

As shown in fig. 9, before the stopper rod is inserted into the copper tube, the movable claw 31 is kept in an initial state, so that the stopper rod is convenient to enter the copper tube 4, after the stopper rod enters the copper tube 4, the movable core rod 2 is pressed down forcefully, the movable claw 31 is ejected out to contact with the inner wall of the copper tube 4, the stopper rod is further inserted into the copper tube 4 until the movable claw 31 is contacted with the end part of the copper net 5 in the copper tube 4, the copper net 5 is pushed into the copper tube 4 along with the pushing of the stopper rod, after the copper net 5 is pushed into place, the movable core rod 2 is pulled back, and at the moment, the movable claw 31 is retracted to the initial state by the elastic restoring force of the elastic restoring mechanism, so that the stopper rod is convenient to be taken out from the copper tube 4.

The radial dimension of the tail end of the stopper rod is adjusted through the movable claw 31, so that the movable claw 31 is ensured to be in contact with the inner wall of the copper pipe 4, and the problem that the gap between the inner wall of the copper pipe and the stopper rod is too large or too tight due to the inner diameter deformation caused by the change of the outer diameter and the wall thickness of the copper pipe or ellipticity and the like can be avoided.

The radial dimension of the tail end of the stopper rod is adjusted by moving the clamping jaw 31, so that the stopper rod can adapt to copper pipes with different inner diameters, and the adaptation size is wider.

The movable claws 31 in the embodiment are provided with 3 movable claws, the adjacent movable claws are uniformly spaced by 120 degrees, and the movable claws are circumferentially uniformly arranged around the mandrel guide sleeve 1, so that when the movable claws 31 extend out, the movable claws extend out from three circumferential directions of the stopper rod to contact with the inner wall of the copper pipe 4, the stopper rod is ensured to be in a neutral position, and self-centering effect is realized. 3 remove jack catch stretch out and push into copper pipe 4 with copper net 5 balanced, copper net 5 atress is balanced, has avoided unable accurate centering before to lead to one-way propulsion, makes copper net slope, deformation and card lead to pushing into the problem that can't go into in the clearance. Of course, in other embodiments, the moving jaw may be provided with more than 3 moving jaws.

As shown in fig. 4, 5, 7, 8, the elastic return mechanism includes a return spring 33 disposed in parallel with the moving direction of the moving jaw 31 and a spring contact surface 312 provided on the moving jaw 31 for driving the return spring 33 to generate an elastic force, one end of the return spring 33 being fixed. In this embodiment, the fixed end of the return spring 33 faces the outer end of the movable claw 31, the movable end of the return spring 33 faces the inner end of the movable claw 31, and when the movable claw 31 protrudes radially outward of the mandrel guide sleeve 1 under the pressing action of the tapered push head 21, the spring contact surface 312 follows the movable claw 31 to move toward the fixed end of the return spring 33 to press the return spring 33 to generate elastic force. In other embodiments, the fixed end of the return spring 33 faces the inner end of the moving jaw 31, the movable end of the return spring 33 faces the outer end of the moving jaw 31, the spring contact surface 312 is connected with the movable end of the return spring 33, and when the moving jaw 31 protrudes radially outward of the mandrel guide sleeve 1, the spring contact surface 312 moves along with the moving jaw 31 in the outer end direction thereof to stretch the return spring 33 to generate elastic force.

When the force of the tapered push head 21 is removed, the elastic force of the return spring 33 brings the protruded moving jaw 31 back to the original position, and the moving jaw 31 is restored to the original state.

Further, the jaw mechanism 3 further includes a mounting body 32 attached to the distal end of the mandrel guide sleeve 1, and a plurality of jaw mounting grooves provided on the mounting body 32 to be fitted with the moving jaws 31. As shown in fig. 2, the upper end of the mounting body 31 is provided with an opening, and is communicated with the end of the mandrel guide sleeve 1, so that the conical push head 21 extends into the mounting body 32. The mounting body 32 and the mandrel guide sleeve 1 can be connected by welding, screw connection, snap connection or the like. The jaw mounting groove is provided along the radial direction of the mandrel guide sleeve 1, and the jaw mounting groove is opened toward the radial outside of the mandrel guide sleeve 1, and the moving jaw 31 is movably mounted in the jaw mounting groove.

The inner cavity of the mounting main body 32 is hollow, and the claw mounting grooves are communicated with each other for inserting the conical push head 21. If the spacers are arranged between the adjacent space of the jaw mounting grooves, the tapered push head 21 needs to be provided with empty grooves corresponding to the spacers, so that when the tapered push head 21 is inserted into the jaw mechanism 3, a containing space is provided for the spacers, and smooth insertion of the tapered push head 21 is realized.

Further, a spring mounting groove 321 formed by recessing is provided on the bottom surface of the jaw mounting groove, and the return spring 33 is mounted in the spring mounting groove 321.

The movable claw 31 is provided with a spring corresponding groove 311 recessed at a position opposite to the spring mounting groove 321, and a spring contact surface 312 is provided in the spring corresponding groove 311, as shown in fig. 5 and 8, the spring contact surface 312 being an inner end wall surface of the spring corresponding groove 311. The spring mounting groove 321 is opposite to the notch of the spring corresponding groove 311, the return spring 33 is placed in the spring mounting groove 321 and the spring corresponding groove 311, and the spring contact surface 312 is in contact with the axial end surface of the return spring 33.

A positioning portion 34 is provided in the spring mounting groove 312, and the positioning portion 34 is provided at the fixed end of the return spring 33 for fixing the end of the return spring 33. The positioning portion 34 in this embodiment is a pin.

The positioning portion 34 extends into the spring corresponding groove 311, opposite to an end of the spring corresponding groove 311. The positioning portion 34 has a function of fixing one end of the return spring 33, and also has a function of restricting the maximum movement range of the moving jaw 31 in cooperation with the spring corresponding groove 311.

As shown in fig. 5, the state of the elastic restoring mechanism is schematically shown when the moving jaw 31 is in the original state. As shown in fig. 8, the state of the elastic restoring mechanism is schematically shown when the moving jaw 31 is extended outward. At this time, the spring contact surface 312 presses the return spring 33, and the return spring 33 generates an elastic force.

The above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the scope of the present utility model. It will be apparent that the described embodiments are merely some, but not all, embodiments of the utility model. Based on these embodiments, all other embodiments that may be obtained by one of ordinary skill in the art without inventive effort are within the scope of the utility model. Although the present utility model has been described in detail with reference to the above embodiments, those skilled in the art may still combine, add or delete features of the embodiments of the present utility model or make other adjustments according to circumstances without any conflict, so as to obtain different technical solutions without substantially departing from the spirit of the present utility model, which also falls within the scope of the present utility model.

Claims (10)

1. The self-centering net plug rod is characterized by comprising a movable core rod and a core rod guide sleeve, wherein the movable core rod is movably arranged in the core rod guide sleeve and can move in the axial direction of the core rod guide sleeve; the tail end of the movable core rod is provided with a conical push head, the tail end of the core rod guide sleeve is provided with a jaw mechanism, the jaw mechanism comprises a plurality of movable jaws and an elastic reset mechanism, the movable jaws are circumferentially arranged around the core rod guide sleeve and are radially arranged along the core rod guide sleeve, the outer ends of the movable jaws face the radial outer side of the core rod guide sleeve, the inner ends of the movable jaws are close to the central axis direction of the core rod guide sleeve, and the movable jaws are movably installed and can radially move along the core rod guide sleeve; the radial outer wall of the conical push head is an inclined push surface corresponding to the movable claw, the movable claw moves into the claw mechanism through the conical push head, the inclined push surface is in contact with the inner end of the movable claw and radially pushes the movable claw along with continuous insertion of the conical push head, so that the movable claw extends out of the core rod guide sleeve in the radial direction; when the conical push head is separated from the movable claw, the movable claw is retracted and reset through the elastic reset mechanism.

2. The self-centering screen plug according to claim 1, wherein the inner ends of the moving jaws are provided with inclined surfaces corresponding to the direction of inclination of the inclined pushing surfaces.

3. The self-centering screen plug according to claim 1 or 2, wherein the elastic reset mechanism comprises a reset spring arranged in parallel with the moving direction of the moving claw and a spring contact surface arranged on the moving claw and used for driving the reset spring to generate elastic force, one end of the reset spring is fixed, and when the moving claw extends out of the core rod guide sleeve in the radial direction, the spring contact surface moves towards the fixed end of the reset spring along with the moving claw to squeeze the reset spring to generate elastic force or moves away from the fixed end of the reset spring to stretch the reset spring to generate elastic force.

4. A self-centering screen plug as claimed in claim 3, wherein the jaw mechanism further comprises a mounting body connected to the end of the mandrel guide sleeve, a plurality of jaw mounting slots provided on the mounting body adapted to the moving jaws, the mounting body in communication with the end of the mandrel guide sleeve for the tapered pusher to extend into the mounting body; the claw mounting groove is arranged along the radial direction of the core rod guide sleeve, the claw mounting groove is opened towards the radial outer side of the core rod guide sleeve, and the movable claw is movably mounted in the claw mounting groove.

5. The self-centering screen plug of claim 4, wherein the mounting body cavity is hollow, and the jaw mounting grooves are in communication with each other.

6. The self-centering screen plug of claim 4, wherein a recessed spring mounting groove is provided on a bottom surface of the jaw mounting groove, the return spring being mounted in the spring mounting groove.

7. The self-centering screen plug of claim 6, wherein the movable jaw is recessed with a spring corresponding groove at a position opposite to the spring mounting groove, the spring contact surface is disposed in the spring corresponding groove, the spring mounting groove is opposite to the notch of the spring corresponding groove, the return spring is disposed in the spring mounting groove and the spring corresponding groove, and the spring contact surface is in contact with the axial end face of the return spring.

8. The self-centering screen plug of claim 7, wherein a locating portion is provided in the spring mounting groove, the locating portion being provided at a fixed end of the return spring for fixing the end of the return spring.

9. The self-centering screen plug of claim 8, wherein the locating portion extends into the spring-corresponding slot opposite an end of the spring-corresponding slot.

10. Self-centering screen plug as claimed in claim 1 or 2, wherein the number of moving jaws is 3 and the adjacent jaws are evenly spaced apart by 120 °.