Internal expansion type clamp for thin-wall pipe fitting

Abstract

The invention relates to the field of mechanical clamps, in particular to an internal expansion type clamp for a thin-wall pipe fitting. Comprising a machine tool base, a linear sliding rail, a stepped motor base, a left side feeding assembly, a right side feeding assembly and an internal expansion type clamp structure. According to the internal expansion type clamp for the thin-wall pipe fitting, through feeding of the conical center shafts on the two sides, the locking ejector pin on the outer side of the expansion sleeve is pushed, so that the expansion sleeve slides along the expansion sleeve locking nut with the conical surface, the expansion sleeve clamps or loosens the thin-wall pipe fitting, the expansion force can uniformly act on the inner wall of the thin-wall pipe fitting, and the clamping effect is good. Therefore, the problems of surface indentation, deformation, local stress concentration and the like of the thin-walled tube in the clamping process can be effectively avoided, and the size precision and the surface quality of the thin-walled tube are ensured.

Description

Technical Field

[0001] The present invention relates to the field of mechanical fixtures, and particularly to an internal expansion fixture for thin-walled pipe fittings. Background Art

[0002] Thin-walled pipes are widely used in many fields such as machining, aerospace, and automotive manufacturing. Due to their advantages of light weight and material saving, thin-walled pipes play an important role in achieving product lightweight and high performance. However, the processing and clamping of thin-walled pipes have always been difficult problems in the industry. Traditional fixtures have many drawbacks when clamping thin-walled pipes. For example, some external clamping fixtures apply clamping force from the outside of the thin-walled pipe, which easily causes defects such as indentations and deformations on the surface of the thin-walled pipe, seriously affecting the dimensional accuracy and surface quality of the thin-walled pipe. This is unacceptable for the processing of some thin-walled pipe parts with extremely high precision requirements. In addition, for some existing internal expansion fixtures, the expansion structure design is unreasonable and the expansion force distribution is uneven. Not only can they not reliably fix the thin-walled pipe, but also local stress concentration is easily caused in the thin-walled pipe during the expansion process, which in turn leads to the rupture of the thin-walled pipe, greatly reducing the qualified rate of thin-walled pipe processing and increasing production costs at the same time. Summary of the Invention

[0003] The purpose of the present invention is to provide an internal expansion fixture for thin-walled pipes with a simple structure, flexibility and reliability, so as to solve the problems that existing fixtures are prone to cause indentations, deformations on the surface of thin-walled pipes and uneven expansion force distribution when clamping thin-walled pipes. The internal expansion fixture for thin-walled pipes of the present invention enables the expansion force to act uniformly on the inner wall of the thin-walled pipe through a unique expansion structure design, thereby effectively avoiding problems such as surface indentations, deformations and local stress concentration during the clamping process of the thin-walled pipe, ensuring the dimensional accuracy and surface quality of the thin-walled pipe. At the same time, the fixture should have good reliability and stability, be able to reliably fix the thin-walled pipe in various processing environments, improve the qualified rate of thin-walled pipe processing, reduce production costs, and meet the increasing high-precision and high-quality requirements of modern manufacturing for thin-walled pipe processing.

[0004] To achieve the above object, the present invention is solved by adopting the following technical solutions:

[0005] In a first aspect, the present invention provides an internal expansion fixture for thin-walled pipe fittings, which includes:

[0006] A machine tool base,

[0007] A linear slide rail is provided on the machine tool base, a slide table is provided on the linear slide rail, and a first motor for driving the slide table to move along the linear slide rail is provided on one side of the linear slide rail;

[0008] A stepped motor seat is arranged on the slide, and the stepped motor seat comprises an upper stepped motor seat and a lower stepped motor seat;

[0009] A left-side feeding assembly is arranged on the upper step motor seat, and the left-side clamp assembly includes a second motor, a magnetic coupling, a torque sensor, a magnetic coupling and a left conical central shaft which are connected in sequence;

[0010] A right feeding assembly is arranged on the lower step motor seat, and the right feeding assembly comprises a handwheel slide rail, a handwheel slide table, and a right conical center axis arranged on the handwheel slide table, and the left conical center axis and the right conical center axis are kept coaxial;

[0011] The internal expansion clamp structure comprises a core shaft, an expansion sleeve locking nut, an expansion sleeve and an expansion sleeve outer locking ejector, wherein the core shaft is used to be inserted into a thin-walled pipe fitting; the expansion sleeve locking nut is installed on both ends of the core shaft through threads, and the expansion sleeve is arranged on the conical surface of the end of the expansion sleeve locking nut; a conical inner hole is formed on one side of the expansion sleeve outer locking ejector, and the other side is used to abut against the expansion sleeve; the conical surfaces of the left conical central shaft and the right conical central shaft respectively abut against the conical inner holes of the expansion sleeve outer locking ejector on both sides of the core shaft;

[0012] When the left tapered center axis and the right tapered center axis approach each other, the outer locking pins of the expansion sleeves on both sides are pushed, and the expansion sleeves move along the conical surface at the end of the expansion sleeve locking nut to expand and tighten the inner wall of the thin-walled pipe fitting. By adjusting the distance between the left tapered center axis and the right tapered center axis, the expansion sleeve can clamp or loosen the thin-walled pipe fitting.

[0013] As a preferred embodiment, the linear guide rail is connected to the first motor via a coupling.

[0014] As a preferred embodiment, shock-absorbing feet are installed at the bottom corners of the machine tool base.

[0015] As a preferred embodiment, the left conical central axis and the right conical central axis are respectively installed in the left motor seat and the right motor seat, the left motor seat is arranged on the upper step motor seat, and the right motor seat is arranged on the handwheel slide.

[0016] As a preferred embodiment, the left tapered central axis and the right tapered central axis are both installed and fixed by angular contact bearings.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The internal expansion fixture for thin-walled pipe fittings of the present invention can push the locking ejector pins on the outer side of the expansion sleeve through the feeding of the tapered central shafts on both sides, so that the expansion sleeve slides along the expansion sleeve locking nut with a tapered surface, so as to clamp or loosen the thin-walled pipe fittings. The expansion force can act evenly on the inner wall of the thin-walled pipe, thus effectively avoiding problems such as surface indentation, deformation and local stress concentration during the clamping process of the thin-walled pipe, and ensuring the dimensional accuracy and surface quality of the thin-walled pipe. The fixture of the present invention has good reliability and stability, can reliably fix the thin-walled pipe in various processing environments, improve the yield rate of thin-walled pipe processing, reduce the production cost, and meet the increasing high-precision and high-quality requirements of modern manufacturing for thin-walled pipe processing.

[0019] 2. The internal expansion fixture for thin-walled pipe fittings of the present invention can clamp or loosen the thin-walled pipe fittings through the feeding of the tapered central shaft. It can not only adapt to workpieces within a certain inner diameter size range, expanding the application range of the fixture, but also realize clamping and loosening by adjusting the feeding distance of the tapered central shaft. Compared with the traditional structure that requires adjusting nuts or cylinders and manual pull rods, the overall structure is relatively simple and the production preparation cycle is shorter, and it is more suitable for the production of medium and small batch and multi-variety workpieces.

[0020] 3. The cylindrical expansion sleeve adopted by the present invention can realize clamping through overall expansion. Compared with traditional fixtures, it can significantly increase the contact area between the fixture and the inner circular surface of the thin-walled pipe fitting, make the clamping force of the fixture more uniform, and thus effectively reduce the influence of the clamping force on the deformation of the workpiece; in addition, since the hardness of the expansion sleeve is lower than that of other metal workpieces, the workpiece will not be scratched.

[0021] 4. The present invention adopts a non-contact coupling design of a magnetic coupling and a torque sensor to construct a real-time processing state perception system. When it is detected that the torque mutation exceeds the set threshold, the servo motor can immediately brake, thus avoiding unnecessary deformation of the thin-walled pipe fitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the overall structure of the internal expansion fixture for thin-walled pipe fittings of the present invention;

[0023] Figure 2 is Figure 1 the top view of

[0024] Figure 3 is the overall structure diagram of the internal expansion fixture structure;

[0025] Figure 4 is Figure 3 the cross-sectional view of

[0026] Reference numerals in the figure: 1. Machine tool base, 2. Shock-absorbing floor feet, 3. Linear slide rail, 4. Coupling, 5. First motor, 6. Slide table, 7. Step-type motor base, 8. Second motor, 9. Magnetic coupling, 10. Torque sensor, 11. Left motor base, 12. Left tapered center shaft, 13. Angular contact bearing, 14. Thimble for locking the outer side of the expansion sleeve, 15. Mandrel, 16. Locking nut for the expansion sleeve, 17. Expansion sleeve, 18. Right tapered center shaft, 19. Right motor base, 20. Handwheel slide table, 21. Handwheel slide rail, 22. Thin-walled pipe fitting. Detailed implementation mode

[0027] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0028] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0029] Embodiment 1

[0030] Combined with Figure 1, this embodiment provides an internal expansion fixture for thin-walled pipe fittings 22, which includes a machine tool base 1, linear guide rails 3, a stepped motor base 7, a left feed assembly, a right feed assembly, and an internal expansion fixture structure. Four shock-absorbing feet 2 are installed at the bottom of the machine tool base 1, and the shock-absorbing feet 2 are used to stabilize the workbench. The linear guide rails 3 are arranged on the machine tool base 1, and a slide table 6 is arranged on the linear guide rails 3. A first motor 5 for driving the slide table 6 to move along the linear guide rails 3 is arranged on one side of the linear guide rails 3. The first motor 5 is a DC servo motor. Of course, the first motor 5 can also be selected from other motors with the same function in the prior art; the linear guide rails 3 are connected to the first motor 5 through a coupling 4, and the first motor 5 is used in cooperation with the linear guide rails 3 and the slide table 6 to realize the feeding of the workpiece fixture.

[0031] The stepped motor base 7 is arranged on the slide table 6. The stepped motor base 7 includes an upper stepped motor base and a lower stepped motor base; a left feed assembly is arranged on the upper stepped motor base. The left fixture assembly includes a second motor 8, a magnetic coupling 9, a torque sensor 10, a magnetic coupling 9, and a left conical center shaft 12 connected in sequence; the second motor 8 is a DC servo motor. Of course, the second motor 8 can also be selected from other motors with the same function in the prior art. Specifically, the second motor 8 is connected to the torque sensor 10 through a magnetic coupling 9. The torque sensor 10 is used to monitor the surface state of the workpiece during processing in real time. When the torque detected by the torque sensor 10 exceeds the set threshold, the second motor 8 immediately brakes to avoid unnecessary deformation of the thin-walled pipe fitting 22.

[0032] On the other side of the torque sensor 10, there is also a magnetic coupling 9 connected to the left conical center shaft 12 through a left motor base 11. The left motor base 11 internally fixes the left conical center shaft 12 through two angular contact bearings 13 and transmits the torque generated by the second motor 8 to the fixture, thereby realizing the rotation of the workpiece. The right feed assembly is arranged on the lower stepped motor base. The right feed assembly includes a handwheel slide rail 21, a handwheel slide table 20 arranged on the handwheel slide rail 21, and a right conical center shaft 18 arranged on the handwheel slide table 20. The handwheel slide table 20 is used in cooperation with the handwheel slide rail 21 to realize the feeding of the other side fixture. The left conical center shaft 12 and the right conical center shaft 18 are coaxial. The left conical center shaft 12 and the right conical center shaft 18 are respectively installed in a left motor base 11 and a right motor base 19. The left motor base 11 is arranged on the upper stepped motor base, and the right motor base 19 is arranged on the handwheel slide table 20. The left conical center shaft 12 and the right conical center shaft 18 are both installed and fixed through angular contact bearings 13.

[0033] The internal expansion type fixture structure includes a mandrel 15, a sleeve locking nut 16, a sleeve 17, and an outer locking thimble 14 of the sleeve. The mandrel 15 is used to pass through the thin-walled pipe fitting 22. The sleeve locking nut 16 is installed at both ends of the mandrel 15 by threads. The sleeve 17 is cylindrical and is sleeved on the tapered surface at the end of the sleeve locking nut 16. A tapered inner hole is formed on the first side of the outer locking thimble 14 of the sleeve, and the first side can abut against the sleeve 17. The tapered surfaces of the left tapered central shaft 12 and the right tapered central shaft 18 respectively abut against the tapered inner holes of the outer locking thimbles 14 on both sides of the mandrel 15. A circular stepped through hole for accommodating the end of the mandrel 15 is further formed on the second side of the outer locking thimble 14 of the sleeve. The fixture in this embodiment presents a symmetric structure along the central axis. Based on the center line, the parts on the left and right sides are highly symmetric in shape, size, and layout.

[0034] When the left tapered central shaft 12 and the right tapered central shaft 18 approach each other, the outer locking thimbles 14 on both sides are pushed, and the sleeve 17 moves along the tapered surface at the end of the sleeve locking nut 16 to expand and tighten the inner wall of the thin-walled pipe fitting 22. By adjusting the distance between the left tapered central shaft 12 and the right tapered central shaft 18, the sleeve 17 can be clamped or loosened from the thin-walled pipe fitting 22. It can not only adapt to workpieces within a certain inner diameter size range, expanding the application range of the fixture, but also achieve clamping and loosening by adjusting the feed distance of the tapered central shaft. Compared with the traditional structure that requires adjusting nuts or cylinders and manual pull rods, the overall structure is relatively simple and the production preparation cycle is shorter, making it more suitable for the production of medium and small batch and multi-variety workpieces.

[0035] Specifically, the processing process of the internal expansion type fixture for the thin-walled pipe fitting 22 in this embodiment is as follows: At the beginning of processing, the distance between the right tapered central shaft 18 and the left tapered central shaft 12 is shortened by controlling the hand-operated slide 20. When the distance between the two tapered central shafts is shortened to be more than 3 - 5 cm longer than the length of the thin-walled pipe fitting 22, the handwheel slide rail 21 is fixed, and the workpiece is placed between the two tapered central shafts. Then, the hand-operated slide 20 is adjusted again. By squeezing the outer locking thimbles 14 on both sides of the tapered central shaft, the sleeve 17 expands axially, and the assembled sleeve locking nut 17 and the thin-walled pipe fitting 22 are fixed between the two tapered central shafts, thus achieving the clamping purpose.

[0036] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can still be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A thin-walled pipe internal expansion clamp, characterized in that: include: Machine tool base, A linear slide rail is arranged on the machine tool base, a slide table is arranged on the linear slide rail, and a first motor is arranged on one side of the linear slide rail for driving the slide table to move along the linear slide rail; A stepped motor seat is arranged on the slide, and the stepped motor seat comprises an upper stepped motor seat and a lower stepped motor seat; A left-side feeding assembly is arranged on the upper step motor seat, and the left-side clamp assembly includes a second motor, a coupling, a torque sensor, a coupling and a left conical central shaft which are connected in sequence; A right feeding assembly is arranged on the lower step motor seat, and the right feeding assembly comprises a handwheel slide rail, a handwheel slide table arranged on the handwheel slide rail, and a right conical center axis arranged on the handwheel slide table, and the left conical center axis and the right conical center axis are kept coaxial; The internal expansion clamp structure comprises a core shaft, an expansion sleeve locking nut, an expansion sleeve and an expansion sleeve outer locking ejector, wherein the core shaft is used to be inserted into a thin-walled pipe fitting; the expansion sleeve locking nut is installed on both ends of the core shaft through threads, and the expansion sleeve is arranged on the conical surface of the end of the expansion sleeve locking nut; a first side of the expansion sleeve outer locking ejector forms a conical inner hole, and the first side can abut against the expansion sleeve; the conical surfaces of the left conical central shaft and the right conical central shaft respectively abut against the conical inner holes of the expansion sleeve outer locking ejector on both sides of the core shaft, and the second side of the expansion sleeve outer locking ejector also forms a circular stepped through hole for accommodating the end of the core shaft; When the left tapered center axis and the right tapered center axis approach each other, the outer locking pins of the expansion sleeves on both sides are pushed, and the expansion sleeves move along the conical surface at the end of the expansion sleeve locking nut to expand and tighten the inner wall of the thin-walled pipe fitting. By adjusting the distance between the left tapered center axis and the right tapered center axis, the expansion sleeve can clamp or loosen the thin-walled pipe fitting.

2. The internal expansion clamp for thin-walled pipes according to claim 1, characterized in that: The linear slide rail is connected to the first motor via a coupling.

3. The internal expansion clamp for thin-walled pipes according to claim 1, characterized in that: Shock-absorbing feet are installed at the bottom corners of the machine tool base.

4. The internal expansion clamp for thin-walled pipes according to claim 1, characterized in that: The left conical central axis and the right conical central axis are respectively installed in the left motor seat and the right motor seat. The left motor seat is arranged on the upper step motor seat, and the right motor seat is arranged on the handwheel slide.

5. The internal expansion clamp for thin-walled pipes according to claim 4, characterized in that: The left tapered central axis and the right tapered central axis are both installed and fixed via angular contact bearings.

6. The internal expansion clamp for thin-walled pipes according to claim 1, characterized in that: The expansion sleeve is cylindrical.

7. The internal expansion clamp for thin-walled pipes according to claim 1, characterized in that: When the torque detected by the torque sensor exceeds a set threshold, the second motor is braked immediately.

8. A method for operating a thin-walled pipe internal expansion clamp, characterized in that: Based on the thin-walled pipe internal expansion clamp according to any one of claims 1 to 8, the operation method includes: Control the hand wheel slide to shorten the distance between the left tapered center axis and the right tapered center axis to a range greater than the preset length of the thin-walled pipe; Lock the handwheel slide rail, assemble the mandrel, expansion sleeve, expansion sleeve locking nut and thin-walled pipe fittings, and then push the outer locking pins of the two expansion sleeves against the expansion sleeves from the left and right sides; Unlock the handwheel slide rail and control the handwheel slide again to shorten the distance between the left tapered center axis and the right tapered center axis, so that the expansion sleeve expands axially to clamp the thin-walled workpiece.

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