CN210231130U

CN210231130U - Core pulling mechanism of small-diameter pipe bending machine tool

Info

Publication number: CN210231130U
Application number: CN201920924892.2U
Authority: CN
Inventors: Jiazhe Mao; 毛嘉哲; Qiting Zou; 邹奇廷; Shibo Jin; 金时博; Zhaofeng Zhou; 周赵凤
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd
Current assignee: Hongfujin Precision Industry Shenzhen Co Ltd
Priority date: 2019-06-19
Filing date: 2019-06-19
Publication date: 2020-04-03
Anticipated expiration: 2029-06-19

Abstract

The utility model discloses a core pulling mechanism of a small-diameter elbow machine tool, wherein a connecting mechanism (4) comprises a shaft head (6) arranged at the end part of a core pulling main shaft (3), a T-shaped groove (7) is arranged at the front side part of the shaft head (6), a T-shaped block (8) is matched in the T-shaped groove (7), a core bar fixing groove (9) is arranged at the middle part of the T-shaped block (8), and a core bar fixing mechanism (10) is arranged in the groove of the core bar fixing groove (9); a first vertical channel (11) is arranged in the middle of the shaft head (6), a bottom groove (12) is arranged at the lower part of the first vertical channel (11), and the first vertical channel (11), the bottom groove (12) and the T-shaped groove (7) are communicated; the novel anti-theft lock is characterized in that a split pin (13) is arranged in the first vertical channel (11), a handle (14) is arranged on the upper portion of the split pin (13), a locking ring (15) is arranged at the bottom of the split pin (13), the thicknesses of the locking rings (15) are different, and the locking rings (15) are arranged in a bottom groove.

Description

Core pulling mechanism of small-diameter pipe bending machine tool

Technical Field

The utility model relates to a return bend lathe, in particular to mechanism of loosing core of minor diameter return bend lathe.

Background

The full-automatic pipe bending process is a new process developed by combining the traditional pipe bending process with the machine tool industry and the numerical control technology, the full-automatic pipe bending machine is advanced bending processing equipment which is based on the vector pipe bending principle and realizes a complex space three-dimensional pipe fitting through a digital control system according to a program, and an execution mechanism of the full-automatic pipe bending machine mainly comprises a clamping bending mechanism and a pipe feeding rotating mechanism. With the rapid development of microcomputer technology, the current fully automatic tube bender is generally controlled by a microcomputer, and is also called as cnc (computer Numerical control) tube bender. The full-automatic pipe bender has the advantages of being capable of accurately, efficiently and inexpensively manufacturing light and strengthened and toughened bent pipe parts and the like, so that the full-automatic pipe bender can be widely applied to the fields of aviation, aerospace and automobiles. In recent years, with the increasing demand of bending precision of products, the demand of bending forming is gradually increased, and related research on fully automatic pipe bending machines has become a focus in the industry.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a mechanism of loosing core of minor diameter return bend lathe. The utility model discloses not only improved the fastness that main shaft of loosing core and core bar are connected, coupling mechanism easily changes and dismantles moreover, has improved flexibility and the work efficiency who uses. Furthermore, the utility model discloses still have the reliable, stable characteristics of operation.

The technical scheme of the utility model: a core pulling mechanism of a small-diameter pipe bending machine tool comprises a hydraulic cylinder, wherein a core pulling main shaft is arranged inside a shaft body of the hydraulic cylinder, a connecting mechanism is arranged at the end part of the core pulling main shaft, and a core rod is fixed on the connecting mechanism; the connecting mechanism comprises a shaft head arranged at the end part of the core-pulling main shaft, a T-shaped groove is formed in the front side part of the shaft head, a T-shaped block is matched in the T-shaped groove, a core bar fixing groove is formed in the middle of the T-shaped block, and a core bar fixing mechanism is arranged in the groove of the core bar fixing groove; the middle part of the shaft head is provided with a first vertical channel, the lower part of the first vertical channel is provided with a bottom groove, and the first vertical channel, the bottom groove and the T-shaped groove are communicated; the first vertical passage in be equipped with the split pin, the upper portion of split pin is equipped with the handle, the bottom of split pin is equipped with the locking ring, the ring thickness of locking ring is inconsistent, and the locking ring setting is in the kerve.

In the core pulling mechanism of the small-diameter pipe bending machine tool, the hydraulic cylinder comprises a cylinder body, a front end cover is arranged at the front end of the cylinder body, a rear end cover is arranged at the rear end of the cylinder body, a piston cavity is formed inside the cylinder body, a shaft body penetrating through the piston cavity is arranged in the cylinder body, a first sealing ring, a second sealing ring group and a third sealing ring group are arranged on the surface of the shaft body, the first sealing ring is in contact with the wall of the piston cavity, and the second sealing ring group is in contact with the inner wall of the front end cover; the third sealing ring group is contacted with the inner wall of the rear end cover; the front portion of axis body is equipped with first stopper, and the rear portion of axis body is equipped with the second stopper, the main shaft of loosing core fix the inside at the axis body.

In the core pulling mechanism of the small-diameter pipe bending machine tool, a support plate is arranged at the bottom of the T-shaped groove on the shaft head.

In the core pulling mechanism of the small-diameter pipe bending machine tool, the core rod fixing mechanism comprises a first threaded hole formed in the upper part of the T-shaped block, and the first threaded hole is communicated with the core rod fixing groove; and a locking column is matched with the inner thread of the first threaded hole.

In the core pulling mechanism of the small-diameter pipe bending machine tool, the core rod fixing mechanism comprises a middle groove formed in the middle of a T-shaped block, a second vertical channel is formed in the upper portion of the T-shaped block, a second threaded hole is formed in the side portion of the T-shaped block, the front portion of the middle groove is communicated with the second threaded hole, and the rear portion of the middle groove is communicated with the second vertical channel; the end part of the core rod is engaged in the middle groove, the bottom surface of the end part of the core rod is provided with a bottom hole, the second threaded hole is internally provided with a locking screw, the locking screw passes through the second threaded hole and the bottom hole and then penetrates through the other side of the T-shaped block, and the end part of the locking screw is provided with a nut.

In the core pulling mechanism of the small-diameter pipe bending machine tool, a fixing clamp shell is arranged at the lower part of the T-shaped block, an end sheet is arranged at one side of the fixing clamp shell, an end hole matched with the end part of the core rod is formed in the end sheet, and an end buckle is arranged at the upper part of the end sheet; the other side of the fixed clamping shell is provided with an inner sheet, an inner buckle is arranged above the inner sheet, and the inner buckle penetrates through the second vertical channel from bottom to top and is reversely buckled on the upper surface of the T-shaped block; the bottom surface of the fixing clamp shell is provided with a bracket, and the lower part of the locking screw is matched with the bracket.

In the core pulling mechanism of the small-diameter pipe bending machine tool, the rod body of the locking screw is provided with the elastic sleeve, the elastic sleeve comprises a base part sleeved on the upper part of the rod body of the screw and a bearing part sleeved in the middle of the rod body of the screw, a limiting step is arranged between the base part and the bearing part, and a bearing slope is arranged outside the bearing part.

In the core pulling mechanism of the small-diameter pipe bending machine tool, the upper part of the cylinder body is provided with a first support frame, a first slide rail is arranged on the first support frame in a penetrating manner, two ends of the support frame are provided with support plates, and 2 middle limiting blocks are arranged on the first slide rail and in the support plates; the axis body on be equipped with the axis body stopper, the tip and the axis body stopper of first slide rail are fixed mutually.

In the core pulling mechanism of the small-diameter pipe bending machine tool, a limit hole is formed in the side part of the cylinder body, and a second slide rail penetrates through the limit hole; the main shaft is provided with a shaft sliding fork, the upper part of the shaft sliding fork is provided with a sliding fork groove, and the second sliding rail is embedded in the sliding fork groove. .

Compared with the prior art, the utility model discloses following beneficial effect has:

1. the utility model discloses tip at the main shaft of loosing core sets up the spindle nose, is provided with the T-shaped groove on the spindle nose, agrees with the T-shaped piece in the T-shaped groove, has still seted up first vertical passageway and kerve simultaneously on the spindle nose, is provided with the split pin in the first vertical passageway, and the bottom of kerve and split pin is equipped with the locking ring, and the ring thickness of locking ring is inconsistent. The handle is when initial position, and the ring thickness of the outside of locking ring (indicate to be close to T-shaped piece one side) is thin, and the ring thickness of inside (indicating to be close to main shaft one side of loosing core) is thicker, and locking ring does not exert an effect to the T-shaped piece this moment, and the T-shaped piece can freely take out, fill in, and when the T-shaped piece was fixed to needs, the twist grip made the thick one side of ring thickness of locking ring rotate to the outside, and the locking ring outwards extrudees the T-shaped piece, makes T-shaped piece closely withstand with the T-shaped groove, realizes that the T-shaped piece is fixed at the spindle nose. Adopt above-mentioned structure to make the utility model discloses it is more convenient changing suitable T-shaped piece, and the T-shaped piece is fixed under the user state also more firm. The T-shaped piece is as the core bar connecting piece, is the connection midbody of connecting main shaft and the core bar of loosing core (be equipped with the core bar fixed slot in the T-shaped piece, and the core bar fixed slot is used for fixed core bar, consequently looses core the main shaft and passes through the T-shaped piece and be connected with the core bar and fix, consequently, the utility model discloses a structure can be so that the core bar is more firm and stable with being connected of loosing core the main shaft, and the core bar is also more convenient with change, installation and the dismantlement of the main.

2. Further, T-shaped piece middle part be equipped with the mesolot, the tip and the mesolot of core bar agree with mutually, be equipped with the second screw hole on the T-shaped piece, the bottom hole has been seted up to the tip bottom of core bar, locking screw passes second screw hole and bottom hole and nut and is fixed mutually to fix T-shaped piece and core bar mutually, this structure has improved the convenience of installation and dismantlement on the one hand, on the other hand has also improved the firmness of connecting. In addition, the elastic sleeve is arranged outside the locking screw, the middle of the rod body of the elastic sleeve is provided with the pressure-bearing part with the pressure-bearing slope, and when the locking screw is screwed inwards, the elastic sleeve can further improve the fixing firmness degree of the locking screw and the core rod, so that the quality of the bent pipe caused by looseness and displacement of the core rod due to insecure fixing is prevented. Furthermore, a fixing clamp shell is arranged at the lower part of the T-shaped block, and the structural design of the fixing clamp shell can connect and integrate the locking screw, the T-shaped block, the nut and the core rod together on one hand, and also improve the connection stability on the other hand.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

fig. 2 is a cross-sectional view of the present invention;

FIG. 3 is a schematic structural view of the connection between the spindle head of the core-pulling spindle and the T-shaped block;

FIG. 4 is a schematic view of the connection of the T-block and the mandrel;

FIG. 5 is a schematic view of a connection section of a T-block and a core rod;

FIG. 6 is a schematic view of the mating structure of the T-shaped slot and the T-shaped block;

fig. 7 is a schematic structural diagram of the first slide rail and the second slide rail.

Detailed Description

The following description is made with reference to the accompanying drawings and examples, but not to be construed as limiting the invention.

Example (b): a core pulling mechanism of a small-diameter pipe bending machine tool is shown in attached figures 1 and 2 and comprises a hydraulic cylinder 1, a core pulling main shaft 3 is arranged inside a shaft body 2 of the hydraulic cylinder 1, a connecting mechanism 4 is arranged at the end part of the core pulling main shaft 3, and a core rod 5 is fixed on the connecting mechanism 4; the hydraulic cylinder 1 comprises a cylinder body 16, a front end cover 17 is arranged at the front end of the cylinder body 16, a rear end cover 18 is arranged at the rear end of the cylinder body 16, the front end cover and the rear end cover are fixed on two sides of the cylinder body through screws, sealing rings can be arranged at the connecting flanges of the front end cover and the rear end cover to ensure the sealing of the cylinder body, a piston cavity 19 is formed inside the cylinder body 16, and a shaft body 2 penetrating through the piston cavity 19 is arranged in the cylinder body 16. The surface of the shaft body 2 is provided with a first sealing ring 21, a second sealing ring group 22 and a third sealing ring group 23, the first sealing ring 21 is contacted with the cavity wall of the piston cavity 19, and the second sealing ring group 22 is contacted with the inner wall of the front end cover 17; the third seal ring group 23 is in contact with the inner wall of the rear end cover 18, and the arrangement of the seal rings ensures the sealing performance of the shaft body in the moving process, so the technical schemes are conventional technical schemes in the hydraulic and pneumatic fields, and therefore, the detailed description is omitted. The front portion of axis body 2 is equipped with first stopper 24, and the rear portion of axis body 2 is equipped with second stopper 25, the main shaft 3 of loosing core fix in the inside of axis body 2, as shown in figure 2, can fixed by interference fit or screw-thread fit. As shown in fig. 7, a first support frame 30 is arranged at the upper part of the cylinder body 16, a first slide rail 31 penetrates through the first support frame 30, support plates 26 are arranged at two ends of the

support frame

30, and 2 middle limit blocks 33 are arranged on the first slide rail 31 and in the support plates 26; the axis body 2 on be equipped with axis body stopper 34, the tip and the axis body stopper 34 of first slide rail 31 are fixed mutually, axis body stopper 34 and second stopper 25 prevent that the flexible removal of axis body is excessive as the spacing part at axis body both ends. A limiting hole 40 is formed in the side part of the cylinder body 16, and a second slide rail 41 penetrates through the limiting hole 40; the core-pulling main shaft 3 is provided with a shaft sliding fork 42, the upper part of the shaft sliding fork 42 is provided with a sliding fork groove 43, a second sliding rail 41 is embedded in the sliding fork groove 43, the shaft sliding fork is U-shaped, the bottom of the shaft sliding fork is fixed on the core-pulling main shaft through a screw, the screw is screwed down to prevent the shaft sliding fork from rotating, the sliding fork groove is formed in the outer side of the shaft sliding fork, and the second sliding rail penetrates through the sliding fork groove. The setting up of first slide rail and second slide rail provides the axis body on the one hand and looses core the flexible spacing of main shaft, and on the other hand improves the axis body and looses core the stability that the main shaft removed, plays the effect of auxiliary stay. As shown in fig. 3 and 6, the connecting mechanism 4 includes a shaft head 6 disposed at an end of the core-pulling main shaft 3, a T-shaped groove 7 is disposed at a front side portion of the shaft head 6, a T-shaped block 8 is fitted in the T-shaped groove 7, a core bar fixing groove 9 is disposed in a middle portion of the T-shaped block 8, the core bar fixing groove is in a cylindrical groove shape and is used for inserting a rod-shaped core bar, and a core bar fixing mechanism 10 is disposed in a groove of the core bar fixing groove; a first vertical channel 11 is arranged in the middle of the shaft head 6, a bottom groove 12 is arranged at the lower part of the first vertical channel 11, the first vertical channel is a vertically downward cylindrical groove, the bottom groove is a cake-shaped groove arranged at the bottom of the first vertical channel, and the first vertical channel 11, the bottom groove 12 and the T-shaped groove 7 are communicated; a cotter 13 is arranged in the first vertical channel 11, and a fixing gasket is arranged at the bottom of the cotter and penetrates through the shaft head to prevent the cotter from moving and separating from the first vertical channel. The upper part of the cotter 13 is provided with a handle 14, the bottom of the cotter 13 is provided with a locking ring 15, the ring thickness of the locking ring 15 is inconsistent, and the locking ring 15 is arranged in the bottom groove; the bottom of the T-shaped groove 7 on the shaft head 6 is provided with a support plate 26, the core rod fixing mechanism 10 comprises a first threaded hole 51 formed in the upper part of the T-shaped block 8, and the first threaded hole 51 is communicated with the core rod fixing groove 9; the first threaded hole 51 is internally threaded with a locking post 27. The handle is when initial position, at this moment, the ring thickness of the outside of locking ring (indicate to be close to T-shaped piece one side) is thin, the ring thickness of inside (indicate to be close to main shaft one side of loosing core) is thicker, locking ring does not exert an effect to the T-shaped piece this moment, the T-shaped piece can freely take out, fill in, when the T-shaped piece is fixed to needs, the handle rotates, the thick one side of ring thickness that makes the locking ring rotates to the outside, the locking ring outwards extrudees the T-shaped piece, make the T-shaped piece closely withstand with the T-shaped groove, realize that the T-shaped piece is fixed at the spindle nose. Adopt above-mentioned structure to make the utility model discloses it is more convenient to change suitable T-shaped piece, and the T-shaped piece is fixed under the user state also more firm. The T-shaped piece is as the core bar connecting piece, is the connection midbody of connecting main shaft and the core bar of loosing core (be equipped with the core bar fixed slot in the T-shaped piece, and the core bar fixed slot is used for fixed core bar, consequently looses core the main shaft and passes through the T-shaped piece and be connected with the core bar and fix, consequently, the utility model discloses a structure can be so that the core bar is more firm and stable with being connected of loosing core the main shaft, and the core bar is also more convenient with change, installation and the dismantlement of the main.

Example 2: as another embodiment, as shown in fig. 4 and 5, the core rod fixing mechanism 10 includes a middle groove 101 formed in the middle of the T-block 8, the middle groove is a groove with an arc-shaped upper portion and vertical surfaces at both sides, and is just matched with the end of the core rod. The upper part of the T-block 8 is provided with a second vertical channel 102, which may be a rectangular groove running through the T-block vertically downwards. The side part of the T-shaped block 8 is provided with a second threaded hole 103, the front part of the middle groove 101 is communicated with the second threaded hole 103, and the rear part of the middle groove 101 is communicated with a second vertical channel 102; the end part of the core rod 5 is fitted in the middle groove 101, a bottom hole 104 is formed in the bottom surface of the end part of the core rod 5, a locking screw 105 is arranged in the second threaded hole 103, the locking screw 105 passes through the second threaded hole 103 and the bottom hole 104 and then penetrates through the other side of the T-shaped block 8, and a nut 106 is arranged at the end part of the locking screw 105. The lower part of the T-shaped block 8 is provided with a fixed clamping shell 107, the fixed clamping shell can be obtained by pressing a metal sheet or can be formed by one-time molding of plastics through a die, one side of the fixed clamping shell 107 is provided with an end sheet 108, the end sheet 108 is provided with an end hole 109 matched with the end part of the core rod 5, and the upper part of the end sheet 108 is provided with an end buckle 110; an inner sheet 111 is arranged on the other side of the fixed clamping shell 107, an inner buckle 112 is arranged above the inner sheet 111, and the inner buckle 112 penetrates through the second vertical channel 102 from bottom to top and is buckled on the upper surface of the T-shaped block 8 in an inverted manner; the bottom surface of the fixing clip shell 107 is provided with a bracket 113, and the lower part of the locking screw 105 is matched with the bracket 113. Furthermore, the shaft of the locking screw 105 is provided with an elastic sleeve 114, the elastic sleeve 114 comprises a base part 115 sleeved on the upper part of the shaft of the locking screw 105 and a pressure-bearing part 116 sleeved on the middle part of the shaft of the locking screw, a limit step 117 is arranged between the base part 115 and the pressure-bearing part 116, and a pressure-bearing slope 118 is arranged outside the pressure-bearing part 116. When the core rod is connected, the end part of the core rod is inserted into the middle groove, and the locking screw penetrates through the second threaded hole and the bottom hole to be fixed with the nut, so that the T-shaped block is fixed with the core rod, the structure improves the convenience of installation and disassembly on one hand, and the firmness of connection on the other hand is also improved. In addition, the elastic sleeve is arranged outside the locking screw, the middle of the rod body of the elastic sleeve is provided with the pressure-bearing part with the pressure-bearing slope, and when the locking screw is screwed inwards, the elastic sleeve can further improve the fixing firmness degree of the locking screw and the core rod, so that the quality of the bent pipe caused by looseness and displacement of the core rod due to insecure fixing is prevented. Furthermore, a fixing clamp shell is arranged at the lower part of the T-shaped block, and the structural design of the fixing clamp shell can connect and integrate the locking screw, the T-shaped block, the nut and the core rod together on one hand, and also improve the connection stability on the other hand.

Claims

1. A core pulling mechanism of a small-diameter pipe bending machine tool comprises a hydraulic cylinder (1), wherein a core pulling main shaft (3) is arranged inside a shaft body (2) of the hydraulic cylinder (1), a connecting mechanism (4) is arranged at the end part of the core pulling main shaft (3), and a core rod (5) is fixed on the connecting mechanism (4); the method is characterized in that: the connecting mechanism (4) comprises a shaft head (6) arranged at the end part of the core-pulling main shaft (3), a T-shaped groove (7) is formed in the front side part of the shaft head (6), a T-shaped block (8) is fit in the T-shaped groove (7), a core bar fixing groove (9) is formed in the middle of the T-shaped block (8), and a core bar fixing mechanism (10) is arranged in the groove of the core bar fixing groove (9); a first vertical channel (11) is arranged in the middle of the shaft head (6), a bottom groove (12) is arranged at the lower part of the first vertical channel (11), and the first vertical channel (11), the bottom groove (12) and the T-shaped groove (7) are communicated; the novel anti-theft lock is characterized in that a split pin (13) is arranged in the first vertical channel (11), a handle (14) is arranged on the upper portion of the split pin (13), a locking ring (15) is arranged at the bottom of the split pin (13), the thicknesses of the locking rings (15) are different, and the locking rings (15) are arranged in a bottom groove.

2. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 1, characterized in that: the hydraulic cylinder (1) comprises a cylinder body (16), a front end cover (17) is arranged at the front end of the cylinder body (16), a rear end cover (18) is arranged at the rear end of the cylinder body (16), a piston cavity (19) is formed inside the cylinder body (16), a shaft body (2) penetrating through the piston cavity (19) is arranged in the cylinder body (16), a first sealing ring (21), a second sealing ring group (22) and a third sealing ring group (23) are arranged on the surface of the shaft body (2), the first sealing ring (21) is in contact with the cavity wall of the piston cavity (19), and the second sealing ring group (22) is in contact with the inner wall of the front end cover (17); the third sealing ring group (23) is in contact with the inner wall of the rear end cover (18); the front part of the shaft body (2) is provided with a first limiting block (24), the rear part of the shaft body (2) is provided with a second limiting block (25), and the core-pulling main shaft (3) is fixed in the shaft body (2).

3. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 1, characterized in that: and a support plate (26) is arranged at the bottom of the T-shaped groove (7) on the shaft head (6).

4. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 1, characterized in that: the core bar fixing mechanism (10) comprises a first threaded hole (51) formed in the upper portion of the T-shaped block (8), and the first threaded hole (51) is communicated with the core bar fixing groove (9); the first threaded hole (51) is internally threaded with a locking column (27).

5. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 1, characterized in that: the core bar fixing mechanism (10) comprises a middle groove (101) formed in the middle of the T-shaped block (8), a second vertical channel (102) is formed in the upper portion of the T-shaped block (8), a second threaded hole (103) is formed in the side portion of the T-shaped block (8), the front portion of the middle groove (101) is communicated with the second threaded hole (103), and the rear portion of the middle groove (101) is communicated with the second vertical channel (102); the end part of the core rod (5) is fitted in the middle groove (101), a bottom hole (104) is formed in the bottom surface of the end part of the core rod (5), a locking screw (105) is arranged in the second threaded hole (103), the locking screw (105) passes through the second threaded hole (103) and the bottom hole (104) and then penetrates through the other side of the T-shaped block (8), and a nut (106) is arranged at the end part of the locking screw (105).

6. The core pulling mechanism of a small-diameter pipe bending machine according to claim 5, characterized in that: a fixed clamping shell (107) is arranged at the lower part of the T-shaped block (8), an end sheet (108) is arranged at one side of the fixed clamping shell (107), an end hole (109) matched with the end part of the core rod (5) is formed in the end sheet (108), and an end buckle (110) is arranged at the upper part of the end sheet (108); an inner sheet (111) is arranged on the other side of the fixed clamping shell (107), an inner buckle (112) is arranged above the inner sheet (111), and the inner buckle (112) penetrates through the second vertical channel (102) from bottom to top and is reversely buckled on the upper surface of the T-shaped block (8); the bottom surface of the fixing clip shell (107) is provided with a bracket (113), and the lower part of the locking screw (105) is matched with the bracket (113).

7. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 6, characterized in that: the locking screw is characterized in that an elastic sleeve (114) is arranged on the shaft body of the locking screw (105), the elastic sleeve (114) comprises a base part (115) sleeved on the upper part of the shaft body of the locking screw (105) and a bearing part (116) sleeved on the middle part of the shaft body of the locking screw, a limiting step (117) is arranged between the base part (115) and the bearing part (116), and a bearing slope (118) is arranged on the outer side of the bearing part (116).

8. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 2, characterized in that: a first support frame (30) is arranged at the upper part of the cylinder body (16), a first sliding rail (31) penetrates through the first support frame (30), support plates (26) are arranged at two ends of the support frame (30), and 2 middle limiting blocks (33) are arranged on the first sliding rail (31) and in the support plates (26); the shaft body (2) is provided with a shaft body limiting block (34), and the end part of the first sliding rail (31) is fixed with the shaft body limiting block (34).

9. The core-pulling mechanism of a small-diameter pipe bending machine according to claim 2, characterized in that: a limiting hole (40) is formed in the side part of the cylinder body (16), and a second sliding rail (41) penetrates through the limiting hole (40); the core-pulling main shaft (3) is provided with a shaft sliding fork (42), the upper part of the shaft sliding fork (42) is provided with a sliding fork groove (43), and the second sliding rail (41) is embedded in the sliding fork groove (43).