CN113617873A

CN113617873A - Bushing and extrusion tool with same

Info

Publication number: CN113617873A
Application number: CN202110938133.3A
Authority: CN
Inventors: 盛利涛
Original assignee: Yantai Anxifeige Material Fatigue Technology Co ltd
Current assignee: Yantai Anxifeige Material Fatigue Technology Co ltd
Priority date: 2021-08-16
Filing date: 2021-08-16
Publication date: 2021-11-09
Anticipated expiration: 2041-08-16
Also published as: CN113617873B

Abstract

The invention discloses a bushing and an extrusion tool with the bushing, wherein the bushing comprises the following components in parts by weight: the bushing is made of liquid metal; the bushing is provided with a through hole; the extrusion tool comprises a main body, a containing arm, a reinforced tool connecting part, a core print and a drive control mechanism arranged on the main body; the drive control mechanism comprises a storage bin arranged on the main body, a pressurizing spring arranged on the storage bin, a sliding block fixedly connected with the storage arm and slidably connected with the storage bin, a drive hole arranged on the storage arm, a drive rod rotatably connected with the drive hole, a special-shaped groove arranged on the drive rod, a special-shaped rod, a linkage rod connected with the special-shaped rod, a control flange fixedly connected with the linkage rod, a sliding shaft rotatably connected with the control flange and a drive shaft slidably connected with the sliding shaft; the driving control mechanism is arranged, so that the working speed of the extrusion tool can be adjusted according to the wall thickness of the lining, and the optimal processing and strengthening work can be achieved.

Description

Bushing and extrusion tool with same

Technical Field

The invention belongs to the technical field of extrusion tools, and particularly relates to a bushing and an extrusion tool with the bushing.

Background

The existing bushing is made of metal, a gap is reserved in the axial direction, the performance is limited in the using process, and the bushing cannot be recovered after deformation, so that the existing bushing is mostly disposable, and the reinforced bushing can flow into the inner hole to form the convex ridge, and needs to be removed by a special cutter in the later period, so that the processing cost is increased; the corresponding extrusion tool generally comprises a core print and a core rod, when the extrusion tool works, a lining sleeve can be sleeved on the core rod, a drawing gun can drive the core rod and the core print to penetrate through the lining sleeve, the lining sleeve is fastened and reamed, the speed control is lacked, and the strengthening of the lining sleeve is adversely affected.

Disclosure of Invention

The invention provides a liquid metal bushing and an extrusion tool with the same, aiming at overcoming the defects of the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

a bushing comprises a sleeve and a through hole axially penetrating through the sleeve; the sleeve is made of liquid metal and is in a closed ring shape; .

The amorphous material is a liquid metal alloy material.

The liquid metal alloy material is a Zr-based amorphous alloy.

The bushing pressing tool comprises a main body, a containing arm connected to the main body in a sliding mode, a strengthening tool connecting part detachably connected to the containing arm, a core print connected with the strengthening tool connecting part, and a driving control mechanism arranged on the main body; the drive control assembly comprises a containing bin arranged on the main body, a pressurizing spring arranged on the containing bin, a sliding block fixedly connected with the containing arm and slidably connected with the containing bin, a drive hole arranged on the containing arm, a drive rod rotatably connected with the drive hole, a special-shaped groove arranged on the drive rod, a special-shaped rod slidably connected with the special-shaped groove, a linkage rod connected with the special-shaped rod, a control flange fixedly connected with the linkage rod, a sliding shaft rotatably connected with the control flange and a drive shaft slidably connected with the sliding shaft;

preferably, the rear side of the theme is provided with a universal interface which can be quickly connected with the motor;

preferably, the driving rod is connected with the driving hole through threads;

the driving shaft at the rear side of the universal interface is connected with the motor, the core head and the strengthening tool connecting part are arranged in the through hole of the bushing in a penetrating mode, the motor rotates to drive the driving shaft to rotate and further drive the sliding shaft to rotate, the sliding shaft drives the control flange to rotate, the special-shaped rod drives the driving rod to rotate through the special-shaped groove, the sliding block drives the driving rod to rotate under the action of the thread, the containing arm is recovered along the containing bin, further, the deformed core head starts to pass through the bushing, the core head with the larger diameter starts to generate pressure on the inner wall of the bushing, and the inner hole of the bushing is gradually expanded; the rotary motion through the actuating lever converts the linear motion of accomodating the arm into, makes the speed of motion become more controllable, simultaneously, can enlarge the movement distance of accomodating the arm through the screw thread, makes the stroke control at core head and intensive instrument connection position more accurate, can realize slower drawing, reduces the resilience of bush after the deformation, improves fashioned quality.

The drive control assembly further comprises a drive plate fixedly connected to the drive rod, an outer gear arranged on the drive plate, a regulating bin arranged on the main body, a regulating plate fixedly connected to the regulating bin, a plurality of regulating shafts rotatably connected to the regulating plate, a planetary gear fixedly connected to the regulating shafts, a central gear fixedly connected to the control flange, a buffer bin communicated with the special-shaped groove, a regulating valve rotatably connected to the regulating bin, a reset spring arranged on the regulating bin, a regulating handle fixedly connected to the regulating valve, and a starting groove arranged on the regulating bin; preferably, the regulating valve is in threaded connection with the regulating bin; when the wall thickness of the bushing is thick, the connection part of the core head and the strengthening tool needs to have larger pulling force to perform reaming work on the bushing, the adjusting handle is stirred along the starting groove to drive the adjusting valve to rotate, the adjusting valve descends along the adjusting bin under the action of threads and drives the adjusting spring to descend, the adjusting spring generates pressure on the control flange to drive the control flange to press downwards, the special-shaped rods are staggered in the special-shaped groove, the special-shaped rods enter the buffer bin, the central gear is meshed with the planetary gear, and the planetary gear drives the outer gear to rotate to further drive the driving rod to rotate; the regulating valve has the effect of gear control, and the rotating speed of the driving rod is changed by changing the transmission ratio between the driving shaft and the driving plate, so that the torsion of the driving rod is improved, and further, greater tension is provided for the connecting part of the accommodating arm and the strengthening tool, and the regulating valve is used for coping with the reaming of the bushing with thicker wall thickness; through the arrangement of the regulating valve, a proper gear can be selected according to the actual wall thickness of the bushing, when the wall thickness is small, the driving shaft directly drives the driving rod to rotate, the rotating speed is high, and the machining speed is high; when the wall thickness of the bush is larger, the rotating speed is reduced through the planetary gear, the torsion is increased, the reaming work of the bush with the large wall thickness can be completed under the condition that the driving force is not changed, and the forming quality of the bush and the adaptability of the extrusion tool are improved.

An overload protection assembly is arranged in the adjusting bin; the overload protection assembly comprises a control flange mounting block, a plurality of pressure holes, pressure springs, pressure arms and a pressure groove, wherein the control flange mounting block is fixedly connected with the overload protection assembly; when the reaming of core print in the bush received great resistance, the motion of actuating lever was returned and is hindered, the screw thread on actuating lever surface will bear great axial load, the drive shaft drives the sliding shaft and rotates, when the junction between flange mounting piece and the sliding shaft had great rotation resistance, the head of pressure arm can pop out from the pressure tank, extrusion pressure spring got back to in the pressure port, the sliding shaft will no longer drive the control flange and rotate, actuating lever stall avoids the screw thread of actuating lever to be destroyed the damage that arouses the machine.

A front structure chamfer is arranged on the core print; the range of the front structure chamfer is 10-15 degrees.

A rear structure chamfer is arranged on the core print; the value range of the rear structure chamfer is 1-2 degrees.

A working platform is arranged between the front structure chamfer and the rear structure chamfer; the length range of the working platform is 1-6 mm.

A plurality of guide rails are arranged in the storage bin; the sliding block is provided with a guide groove matched with the guide rail; the cooperation of guide rail guide slot can avoid accomodating the arm and taking place to rotate when carrying out the fore-and-aft movement.

The quick connection assembly comprises a mounting head arranged at the connection part of the strengthening tool, a mounting port arranged on the core head, a fixed connection part fixedly connected with a connecting arm of the mounting head, a stop block fixedly connected with the connecting arm, a limiting bin arranged on the core head, an expansion inclined plane arranged on the limiting bin, a stop barrel slidably connected with the limiting bin, a round platform fixedly connected with the stop barrel, a plurality of limiting holes arranged on the round platform, balls fixedly connected with the limiting holes, an unlocking groove arranged on the core head, an unlocking block slidably connected with the unlocking groove, a linkage hole communicated with the unlocking groove and the limiting bin, a connecting rod fixedly connected with the stop barrel and slidably connected with the linkage hole, a linkage spring sleeved on the connecting rod, an unlocking bin arranged on the unlocking block, a plug fixedly connected with the connecting rod, and an unlocking spring arranged on the unlocking bin, An unlocking part fixedly connected to the unlocking block; the diameter of the brake block is larger than that of the connecting arm; a quick connect assembly is provided that will first separate the core print from the reinforcement tool attachment by pulling the unlocking portion 618 and, further, sleeve the bushing over the reinforcement tool attachment to align the mounting opening of the core print with the mounting head. The pressure is applied along the axial direction of the connection part of the strengthening tool, the brake block is extruded by the ball to drive the stop to slide in the limit bin, the ball rolls along the expansion inclined plane and is compressed by the linkage spring, further, the stop block passes through the brake ball, the linkage spring is released to drive the stop cylinder to descend, the ball is extruded by the expansion inclined plane, the center of the ball is closed, the connecting arm is extruded, and the connection part of the core head and the strengthening tool is fixedly connected; the core head can be quickly installed and detached after the construction is finished through quick case hypothesis, and the efficiency is improved.

In summary, the invention has the following advantages: the rotary motion of the driving rod is converted into the linear motion of the containing arm, so that the motion speed becomes more controllable, meanwhile, the motion distance of the containing arm can be enlarged through threads, the speed control of the connecting part of the core print and the strengthening tool is more accurate, the slower stretching can be realized, the rebound of the bushing after deformation is reduced, and the forming quality is improved;

the driving control assembly is arranged, so that the working speed of the extrusion tool can be adjusted according to the wall thickness of the lining, the size of the base material and the size of the hole diameter, and the optimal processing strengthening effect is achieved.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a front view of the present invention.

Fig. 3 is a cross-sectional view taken along a-a of fig. 2.

Fig. 4 is an enlarged view of a portion a in fig. 3.

Fig. 5 is an exploded view of the present invention.

Fig. 6 is a cross-sectional view taken along line B-B of fig. 2.

Fig. 7 is an enlarged view at B in fig. 6.

Fig. 8 is a perspective view of the bushing of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

1-8, a bushing includes a sleeve and a through bore extending axially through the sleeve; the sleeve is made of liquid metal and is in a closed ring shape; when the bush received circumferential expansion force, elastic deformation can take place for the bush, and the diameter of through-hole can grow, and after the external force disappeared, the diameter of through-hole can resume. The lining made of the liquid metal by the superelasticity can be reused for 5-10 times, and meanwhile, the liquid metal lining does not need to be slotted, so that the convex ridge caused by processing is eliminated, the working procedures are reduced, the using performance of the lining is improved, the use of a lubricant can be reduced due to the low friction coefficient characteristic of the liquid metal, and the working procedure is optimized. A pressing tool with the bushing comprises a main body 1, a receiving arm 11, a strengthening tool connecting part 2, a core print 12 and a driving control mechanism 3; the receiving arm 11 is connected with the main body 1 in a sliding way; the strengthening tool connecting part 2 is detachably connected to the accommodating arm 11; the core print 12 is connected with the strengthening tool connecting part 2; the drive control mechanism 3 is arranged on the main body 1; the driving control mechanism 3 comprises a storage bin 31, a pressurizing spring 32, a sliding block 33, a driving hole 34, a driving rod 35, a special-shaped groove 36, a special-shaped rod 37, a linkage rod 38, a control flange 39, a sliding shaft 310 and a driving shaft 311; the storage bin 31 is arranged on the main body 1; the pressurizing spring 32 is arranged in the storage bin 31; the sliding block 33 is fixedly connected to the receiving arm 11 and is slidably connected to the receiving chamber 31; the driving hole 34 is provided in the storage arm 11; the driving rod 35 is rotatably connected to the driving hole 34; the special-shaped groove 36 is arranged on the driving rod 35; the profiled bar 37 is slidingly connected to the profiled groove 36; the linkage rod 38 is connected with the special-shaped rod 37; the control flange 39 is fixedly connected to the linkage rod 38; the sliding shaft 310 is rotatably connected to the control flange 39; the driving shaft 311 is slidably coupled to the sliding shaft 310.

The special-shaped groove is a regular hexagonal groove; the special-shaped rod is a regular hexagon column matched with a regular hexagon groove

The driving control mechanism 3 further comprises a driving plate 312, an external gear 313, an adjusting bin 314, an adjusting plate 315, an adjusting shaft 316, a return spring 317, a planetary gear 318, a central gear 319, a buffer bin 320, an adjusting valve 321, an adjusting handle 322 and a starting groove 323; the driving plate 312 is fixedly connected to the driving rod 35; the outer gear 313 is provided on the driving plate 312; the adjusting bin 314 is arranged on the main body 1; the adjusting plate 315 is fixedly connected to the adjusting bin 314; the adjusting shaft 316 is rotatably connected to the adjusting plate 315; the return spring 317 is arranged on the adjusting bin 314; the planetary gear 318 is fixedly connected to the adjusting shaft 316; the sun gear 319 is fixedly connected to the control flange 39; the surge bin 320 is in communication with the profile groove 36; the regulating valve 321 is rotatably connected to the regulating bin 314; the adjusting handle 322 is fixedly connected to the adjusting valve 321; the starting groove 323 is arranged on the regulating bin 314.

An overload protection component 5 is arranged in the adjusting bin 314; the overload protection assembly 5 comprises a mounting block 51, a pressure hole 52, a pressure spring 53, a pressure arm 54 and a pressure groove 55; the mounting block 51 is fixedly connected to the control flange 39; the pressure hole 52 is arranged on the mounting block 51; the pressure spring 53 is arranged in the pressure hole 52; the pressure arm 54 is slidably connected to the pressure hole 52; the pressure groove 55 is arranged on the sliding shaft 310;

a front structure chamfer 15 is arranged on the core print 12; the front structural chamfer 15 is 12 °.

A rear structure chamfer 16 is arranged on the core print 12; the rear structural chamfer 16 is 1.3 °.

A working platform is arranged between the front structure chamfer 15 and the rear structure chamfer 16; the length of the working platform is 4mm.

A plurality of guide rails 56 are arranged in the storage bin 31; the sliding block 33 is provided with a guide groove 57 which is matched with the guide rail 56.

The quick connecting assembly comprises a mounting head 61, a mounting opening 62, a connecting arm 63, a stopping block 64, a limiting bin 65, an expansion inclined surface 66, a stopping cylinder 67, a circular truncated cone 68, a limiting hole 69, a ball 610, an unlocking groove 611, an unlocking block 612, a linkage hole 613, a connecting rod 614, a linkage spring 615, an unlocking bin 616, a plug 619, an unlocking spring 617 and an unlocking part 618; the mounting head 61 is arranged at the connection part of the strengthening tool; the mounting port 62 is arranged on the core print; the connecting arm 63 is fixedly connected to the mounting head 61; the stop block 64 is fixedly connected to the connecting arm 63; the limiting bin 65 is arranged on the core print; the expansion inclined plane 66 is arranged in the limiting bin 65; the stopping cylinder 67 is connected with the limiting bin 65 in a sliding mode; the circular truncated cone 68 is fixedly connected to the stop cylinder 67; the limiting hole 69 is formed in the circular truncated cone 68; the ball 610 is fixedly connected to the limiting hole 69; the unlocking groove 611 is formed in the core print; the unlocking block 612 is slidably connected to the unlocking slot 611; the linkage hole 613 communicates the unlocking groove 611 with the limiting bin 65; the connecting rod 614 is fixedly connected to the stopping cylinder 67 and slidably connected to the linkage hole 613; the linkage spring 615 is sleeved on the connecting rod 614; the unlocking bin 616 is arranged on the unlocking block 612; the plug 619 is fixedly connected to the connecting rod 614; the unlocking spring 617 is arranged on the unlocking bin 616; the unlocking part 618 is fixedly connected to the unlocking block 612; the diameter of the brake block is larger than the diameter of the connecting arm 63;

the specific working process is as follows:

the core print is first separated from the consolidation tool attachment by pulling the unlocking portion 618 and, further, the bushing is fitted over the consolidation tool attachment to align the mounting opening 62 of the core print with the mounting head 61. Pressure is applied along the axial direction of the connection part of the strengthening tool, the brake block is extruded by the ball 610 to drive the stopper to slide in the limiting bin 65, the ball 610 rolls along the expansion inclined plane 66, the linkage spring 615 is compressed, further, the stopper 64 penetrates through the brake ball 610, the linkage spring 615 is released to drive the stopper cylinder 67 to descend, the ball 610 is extruded by the expansion inclined plane 66, the center of the country is closed, the connecting arm 63 is extruded, and the core head and the connection part of the strengthening tool form fixed connection;

the driving shaft 311 on the rear side of the universal interface is connected with the motor, the motor rotates to drive the driving shaft 311 to rotate and further drive the sliding shaft 310 to rotate, the sliding shaft 310 drives the control flange 39 to rotate, the special-shaped rod 37 drives the driving rod 35 to rotate through the special-shaped groove, the sliding block 33 drives the driving rod 35 to rotate under the action of the threads, the containing arm 11 is recovered along the containing bin 31, further, the deformed core head 12 starts to pass through the lining, the core head 12 with the larger diameter starts to generate pressure on the inner wall of the lining, and the inner hole of the lining is gradually expanded; the rotary motion through actuating lever 35 converts the linear motion of accomodating arm 11 into, makes the speed of motion become more controllable, simultaneously, can enlarge the movement distance of accomodating arm 11 through the screw thread, makes core 12 more accurate with the stroke control of strengthening the instrument connection position, can realize slower tensile, reduces the resilience of bush after the deformation, improves fashioned quality.

When the wall thickness of the bushing is thick, the connection part of the core print 12 and the strengthening tool needs to have larger pulling force to perform reaming work on the bushing, the adjusting handle 322 is shifted along the starting groove 323 to drive the adjusting valve 321 to rotate, the adjusting valve 321 descends along the adjusting bin 314 under the action of the thread and drives the adjusting spring to descend, the adjusting spring generates pressure on the control flange 39 to drive the control flange 39 to press downwards, the special-shaped rods 37 are staggered in the special-shaped grooves, the special-shaped rods 37 enter the buffer bin 320, the central gear 319 is meshed with the planetary gear 318, and the planetary gear 318 drives the outer gear 313 to rotate to further drive the driving rod 35 to rotate; the adjusting valve 321 has a gear control effect, and changes the rotation speed of the driving rod 35 by changing the transmission ratio between the driving shaft 311 and the driving plate 312, so that the torsion of the driving rod 35 is improved, and a larger pulling force is further provided for the connection part of the receiving arm 11 and the strengthening tool, so as to cope with the reaming of the bushing with a thicker wall; through the arrangement of the regulating valve 321, a proper gear can be selected according to the actual wall thickness of the bushing, when the wall thickness is smaller, the driving shaft 311 directly drives the driving rod 35 to rotate, the rotating speed is higher, and the processing speed is higher; when the wall thickness of the bush is larger, the rotating speed is reduced through the planetary gear 318, the torsion is increased, and under the condition that the driving force is not changed, the reaming work of the bush with the large wall thickness can be completed.

When the core head 12 is subjected to large resistance in reaming in the bushing, the movement of the driving rod 35 is blocked, the thread on the surface of the driving rod 35 is subjected to a large axial load, the driving shaft 311 drives the sliding shaft 310 to rotate, when the joint between the flange mounting block 51 and the sliding shaft 310 has large rotation resistance, the head of the pressure arm 54 pops out of the pressure groove 55, the pressure spring 53 is squeezed, the pressure spring returns to the pressure hole 52, the sliding shaft 310 does not drive the control flange 39 to rotate any more, the driving rod 35 stops rotating, and the damage to the machine caused by the damaged thread of the driving rod 35 is avoided.

While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. A bushing, includes external member and the axial through-hole that runs through the external member, its characterized in that: the sleeve is of amorphous material and is provided in the form of a closed ring.

2. The extrusion tool of claim 1, wherein: the amorphous material is a liquid metal alloy material.

3. A press tool as claimed in claim 2, wherein: the liquid metal alloy material is a Zr-based amorphous alloy.

4. A pressing tool with the bushing of claim 1, comprising a main body (1), a receiving arm (11) slidably connected to the main body (1), a strengthening tool connecting portion (2) detachably connected to the receiving arm (11), a core head (12) connected to the strengthening tool connecting portion (2), a driving control mechanism (3) arranged on the main body (1), and a quick-connect assembly (6) arranged on the main body; the device is characterized in that the drive control mechanism (3) comprises a storage bin (31) arranged on the main body (1), a booster spring (32) arranged on the storage bin (31), a sliding block (33) fixedly connected with the storage arm (11) and slidably connected with the storage bin (31), a drive hole (34) arranged on the storage arm (11), a drive rod (35) rotatably connected with the drive hole (34), a special-shaped groove (36) arranged on the drive rod (35), a special-shaped rod (37) slidably connected with the special-shaped groove (36), a linkage rod (38) connected with the special-shaped rod (37), a control flange (39) fixedly connected with the linkage rod (38), a sliding shaft (310) rotatably connected with the control flange (39) and a drive shaft (311) slidably connected with the sliding shaft (310).

5. The extrusion tool of claim 4, wherein: the drive control mechanism (3) further comprises a drive plate (312) fixedly connected with the drive rod (35), an external gear (313) arranged on the drive plate (312), an adjusting bin (314) arranged on the main body (1), an adjusting plate (315) fixedly connected with the adjusting bin (314), a plurality of adjusting shafts (316) rotatably connected with the adjusting plate (315), and a return spring (317) arranged on the adjusting bin (314), the adjusting mechanism comprises a planetary gear (318) fixedly connected with the adjusting shaft (316), a sun gear (319) fixedly connected with the control flange (39), a buffer bin (320) communicated with the special-shaped groove (36), an adjusting valve (321) rotatably connected with the adjusting bin (314), an adjusting handle (322) fixedly connected with the adjusting valve (321), and a starting groove (323) arranged in the adjusting bin (314).

6. The extrusion tool of claim 4, wherein: an overload protection component (5) is arranged in the adjusting bin (314); the overload protection assembly (5) comprises a control flange (39) mounting block (51), a plurality of pressure holes (52) arranged in the mounting block (51), a pressure spring (53) arranged in the pressure hole (52), a pressure arm (54) connected with the pressure hole (52) in a sliding mode, and a pressure groove (55) arranged in the sliding shaft (310).

7. The extrusion tool of claim 4, wherein: a front structure chamfer (15) is arranged on the core print (12); the value range of the front structure chamfer (15) is 10-15 degrees.

8. The extrusion tool of claim 4, wherein: a rear structure chamfer (16) is arranged on the core print (12); the value range of the rear structure chamfer (16) is 1-2 degrees.

9. The extrusion tool of claim 4, wherein: a working platform is arranged between the front structure chamfer (15) and the rear structure chamfer (16); the length range of the working platform is 1-6mm, and a plurality of guide rails (56) are arranged in the storage bin (31); and the sliding block (33) is provided with a guide groove (57) matched with the guide rail (56).

10. The extrusion tool of claim 9, wherein: the quick connection assembly (6) comprises a mounting head (61) arranged at a connection part of the strengthening tool, a mounting hole (62) arranged on the core head, a connecting arm (63) fixedly connected to the mounting head (61), a stop block (64) fixedly connected to the connecting arm (63), a limiting bin (65) arranged on the core head, an expansion inclined surface (66) arranged on the limiting bin (65), a stopping barrel (67) slidably connected to the limiting bin (65), a circular table (68) fixedly connected to the stopping barrel (67), a plurality of limiting holes (69) arranged on the circular table (68), balls (610) fixedly connected to the limiting holes (69), an unlocking groove (611) arranged on the core head, an unlocking block (612) slidably connected to the unlocking groove (611), and a linkage hole (613) communicating the unlocking groove (611) with the limiting bin (65), A connecting rod (614) which is fixedly connected with the stopping cylinder (67) and is connected with the linkage hole (613) in a sliding way, a linkage spring (615) sleeved on the connecting rod (614), an unlocking bin (616) arranged on the unlocking block (612), a plug (619) fixedly connected with the connecting rod (614), an unlocking spring (617) arranged on the unlocking bin (616), and an unlocking part (618) fixedly connected with the unlocking block (612); the diameter of the brake block is larger than the diameter of the connecting arm (63).