A purely mechanical expansion shaft

Abstract

The utility model relates to the field of expansion shaft, concretely to a pure mechanical type expansion shaft, it includes an expansion mandrel, the multiple sector expansion sheets that the sector expansion sheet radial position is limited to the positioning sleeve of installation in the expansion mandrel end portion and even distribution about the circumferential direction of expansion mandrel, the snap spring of setting at the both ends of expansion mandrel and limiting the axial movement of sector expansion sheet, and the tension spring of being sleeved on the multiple sector expansion sheets and being used to restore the inward contraction of sector expansion sheet, the multiple eccentric circular arc structure surfaces that the circumferential direction is even set on the outer peripheral wall of expansion mandrel, drive the multiple sector expansion sheets to outward unfold or inward contract through the rotation of eccentric circular arc structure surface and the contraction force of tension spring. Therefore, the utility model discloses a mechanical type self -adaptation expansion, effectively solved the positioning failure problem of welding and the machining in the tolerance, and has the precision and efficiency advantage.

Description

Technical Field

[0001] This utility model relates to the field of expansion shafts, and in particular to a purely mechanical expansion shaft. Background Technology

[0002] In the production and processing, especially in welding tubular workpieces with holes, locating shafts are generally used to position these workpieces. During use, the locating shaft is typically inserted into the hole in the workpiece, and other workpieces are then placed against the locating shaft for welding. Existing locating shafts are usually cylinders with a fixed diameter. The fit between the locating shaft and the hole in the workpiece requires high precision; the diameter must be strictly matched. If it is too small, it cannot be inserted; if it is too large, it will loosen, easily leading to welding deviations. If assembly fails due to positioning deviations after welding, the workpiece usually has to be scrapped, increasing rework costs. Even if the positioning is accurate during the welding process, a fixed-diameter locating shaft can still be difficult to remove due to workpiece deformation or weld spatter, potentially causing damage to the workpiece. Utility Model Content

[0003] The purpose of this invention is to address the problem in the prior art where welding deviations occur during the welding process of shafts with fixed diameters with workpieces, which may lead to the scrapping of the workpieces. This invention proposes a purely mechanical expansion shaft.

[0004] The technical solution of this utility model is as follows: A purely mechanical expansion shaft includes an expansion mandrel, a plurality of fan-shaped expansion plates evenly distributed around the circumference of the expansion mandrel, a positioning sleeve installed at the end of the expansion mandrel and restricting the radial position of the fan-shaped expansion plates, snap rings set at both ends of the expansion mandrel to restrict the axial movement of the fan-shaped expansion plates, and tension springs sleeved on the plurality of fan-shaped expansion plates to restore the inward contraction of the fan-shaped expansion plates; a plurality of eccentric arc structure surfaces are evenly arranged along the circumference on the outer peripheral wall of the expansion mandrel, and the rotation of the eccentric arc structure surfaces and the contraction force of the tension springs drive the plurality of fan-shaped expansion plates to expand outward or contract inward.

[0005] Preferably, one end of the expansion mandrel is round, and the other end is hexagonal, which can be directly adapted to a standard hex wrench or other tools to achieve quick assembly and disassembly and torque transmission.

[0006] Preferably, both ends of the expansion mandrel are provided with retaining ring grooves, and the retaining rings are fitted into the retaining ring grooves; multiple fan-shaped expansion plates are provided with tension spring grooves on their outer peripheral walls, and the tension springs are inserted into the multiple tension spring grooves.

[0007] Preferably, it also includes a locating pin; the locating sleeve is clearance-fitted with the expansion mandrel, the locating sleeve can rotate axially around the expansion mandrel, a blind hole is provided on the left cross section of the locating sleeve, the diameter of the blind hole is larger than the inner diameter of the locating sleeve, the ends of multiple fan-shaped expansion pieces are inserted into the blind hole, multiple threaded holes are evenly distributed on the annular wall of the blind hole, each fan-shaped expansion piece is provided with a locating hole opposite to one of the threaded holes, the locating pin is threadedly fitted with the threaded hole and its end is inserted into the locating hole.

[0008] Preferably, the inner diameter of the positioning sleeve is smaller than the outer diameter of the snap ring, forming a mechanical stop to prevent the snap ring from axially dislodging. The diameter of the blind hole is larger than the outer diameter of the fan-shaped expansion piece in its free state, and the maximum expansion diameter of the fan-shaped expansion piece is limited to be less than or equal to the inner diameter of the blind hole through mechanical interference. The depth of the blind hole is greater than the length of the fan-shaped expansion piece that extends into the blind hole.

[0009] Preferably, three eccentric arc structural surfaces and three fan-shaped expansion plates are provided. The three eccentric arc structural surfaces are connected end to end. Each segment of the eccentric arc structural surface covers the gradual transition from the minimum diameter to the maximum diameter of the expansion mandrel. The curved surface connection between two adjacent eccentric arc structural surfaces adopts a rounded transition.

[0010] Preferably, three threaded holes and three positioning holes are provided, three positioning pins are provided, and the outer surface of the positioning sleeve is provided with concave and convex textures to increase friction.

[0011] Compared with the prior art, the present invention has the following beneficial technical effects:

[0012] 1. It does not require any power source for expansion and has no complex internal structure. Through the innovative design of three evenly distributed fan-shaped expansion plates, eccentric mechanical expansion and modular maintenance, it surpasses traditional hydraulic and pneumatic expansion shafts in terms of positioning accuracy, environmental adaptability and cost control. It is especially suitable for extreme working conditions with high pollution, high vibration or no power source.

[0013] 2. The three fan-shaped expansion plates are evenly distributed to ensure uniform force distribution after expansion. Due to the traditional two-piece structure, eccentricity is reduced. The axial limit of the snap ring groove prevents the expansion plates from shifting due to welding vibration.

[0014] 3. The tension spring retracts automatically, and the fan-shaped expansion plate quickly returns to its original position after pressure relief, improving the efficiency of parts replacement; the modular design allows for the replacement of tension springs and expansion plates, resulting in low maintenance costs; and the absence of complex pneumatic and hydraulic systems makes it suitable for highly polluted environments, such as welding workshops. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of one embodiment of the present utility model;

[0016] Figure 2 for Figure 1 Exploded view;

[0017] Figure 3for Figure 1 A sectional view;

[0018] Figure 4 This is a schematic diagram of the expansion mandrel.

[0019] Figure 5 This is a cross-sectional view of the expansion mandrel;

[0020] Figure 6 This is a schematic diagram of the contraction state of the fan-shaped expansion piece;

[0021] Figure 7 This is a schematic diagram of the unfolded state of the fan-shaped expansion piece.

[0022] Reference numerals: 1. Expansion mandrel; 2. Fan-shaped expansion plate; 3. Positioning sleeve; 4. Positioning pin; 5. Snap ring; 6. Tension spring; 7. Eccentric circular arc structure surface; 8. Hexagonal body; 9. Tension spring groove; 10. Threaded hole; 11. Positioning hole; 12. Blind hole. Detailed Implementation

[0023] Example 1

[0024] like Figures 1-5 As shown, this utility model proposes a purely mechanical expansion shaft, comprising an alloy expansion mandrel 1, multiple stainless steel fan-shaped expansion plates 2 evenly distributed around the circumference of the expansion mandrel 1, a positioning sleeve 3 installed at the end of the expansion mandrel 1 and restricting the radial position of the fan-shaped expansion plates 2, retaining springs 5 ​​disposed at both ends of the expansion mandrel 1 to restrict the axial movement of the fan-shaped expansion plates 2, and tension springs 6 sleeved on the multiple fan-shaped expansion plates 2 to restore the inward contraction of the fan-shaped expansion plates 2; multiple eccentric arc structure surfaces 7 are evenly arranged along the circumference on the outer peripheral wall of the expansion mandrel 1, and the rotation of the eccentric arc structure surfaces 7 and the contraction force of the tension springs 6 drive the multiple fan-shaped expansion plates 2 to expand outward or contract inward, and the shortest distance between the outer surface of the eccentric arc structure surface 7 and the axis of the expansion mandrel 1 gradually changes. When the expansion mandrel 1 rotates and pushes the fan-shaped expansion piece 2 outward, the tension spring 6 is stretched and stores energy, and the outer diameter of the fan-shaped expansion piece 2 expands to the set value. When the expansion mandrel 1 rotates in the opposite direction, the pressure of the eccentric surface is released, the tension spring 6 releases its elastic force, and pulls the fan-shaped expansion piece 2 inward to the minimum diameter. After shrinkage, the outer diameter of the fan-shaped expansion piece 2 is in clearance fit with the workpiece hole, and the workpiece can be removed without resistance. Therefore, the expansion shaft must meet the dimensional logic of "minimum diameter < pipe inner diameter < maximum diameter", and the axial length ≥ pipe inner hole depth. This utility model realizes closed-loop control of expansion positioning and rapid reset through the linkage of tension spring and eccentric surface, which has both efficiency and accuracy. The expansion mandrel 1 and the fan-shaped expansion piece 2 adopt a modular segmented design. By changing the length of the module, the shaft length is matched with the pipe inner hole depth.

[0025] like Figure 6 and Figure 7As shown, in this embodiment, three eccentric arc structure surfaces 7 and three fan-shaped expansion plates 2 are provided. The three eccentric arc structure surfaces 7 are connected end to end and are evenly distributed at 120°. Each segment of the eccentric arc structure surface 7 covers the gradual transition from the minimum diameter to the maximum diameter of the expansion mandrel 1. The minimum diameter is 50mm and the maximum diameter is 52mm. The curved joints of two adjacent eccentric arc structure surfaces 7 are connected with a radius of 0.5mm to avoid stress concentration. The inner diameter eccentric arc surface of the three fan-shaped expansion plates 2 is exactly the same as the shape of the three eccentric arc structure surfaces 7 on the outer surface of the expansion mandrel 1, ensuring that the contact surfaces fit completely without interference or gaps. Each segment of the eccentric arc surface covers a range of 120°. The three parts are combined to form a complete expansion adjustment ring. When the expansion mandrel 1 is rotated, the eccentric arc structure surface 7 pushes the fan-shaped expansion plates 2 to move radially synchronously, forming a continuously adjustable expansion range. The surface profile of the eccentric arc structure surface 7 is ≤0.01mm. Therefore, when the expansion mandrel 1 rotates, its radial movement distance is stable, preventing any non-cylindrical shape. The expanded fan-shaped expansion pieces 2, surrounding the axis of the expansion mandrel 1, form an annulus with a cylindrical outer diameter, although a certain gap remains between each fan-shaped expansion piece 2. When the hexagonal 8 at the end of the expansion mandrel 1 is turned with a tool, the eccentric arc structure surface 7 on the surface of the expansion mandrel 1 and the eccentric arc surface inside the fan-shaped expansion pieces 2 form a high-friction motion, providing a fixed support force to the fan-shaped curved surface and preventing the fan-shaped expansion pieces 2 from loosening midway due to changes in support force.

[0026] Example 2

[0027] The present invention proposes a purely mechanical expansion shaft. Compared with Embodiment 1, this embodiment details the structure of the expansion mandrel 1.

[0028] like Figure 4 As shown, one end of the expansion mandrel 1 is circular, and the other end is equipped with a hexagonal body 8, which can be directly adapted to a standard hexagonal wrench or other tools to achieve quick assembly and disassembly and torque transmission.

[0029] like Figure 2 As shown, both ends of the expansion mandrel 1 are provided with retaining ring grooves, and retaining rings 5 ​​are installed in the retaining ring grooves. The distance between the two retaining rings 5 ​​is equal to the length of the fan-shaped expansion piece 2 plus 0.2-0.5mm. The 0.2-0.5mm is the floating gap, which not only restricts axial displacement but also avoids jamming due to thermal expansion. The outer diameter of the retaining ring 5 is larger than the maximum expansion inner diameter of the fan-shaped expansion piece 2 to ensure that the radial expansion of the fan-shaped expansion piece 2 is not interfered with. The retaining ring 5 is used to restrict the axial movement of the fan-shaped expansion piece 2 along the expansion mandrel 1 to ensure that the fan-shaped expansion piece 2 can stably maintain its cylindrical structure. Tension spring grooves 9 are provided on the outer peripheral walls of multiple fan-shaped expansion pieces 2. Tension springs 6 are inserted into multiple tension spring grooves 9, and tension springs 6 are used to enable the fan-shaped expansion piece 2 to automatically retract and reset.

[0030] Example 3

[0031] The present invention proposes a purely mechanical expansion shaft. Compared with Embodiment 1 or Embodiment 2, this embodiment details the structure of the positioning sleeve 3.

[0032] like Figure 2 As shown, the positioning sleeve 3 is clearance-fitted with the expansion mandrel 1, with a clearance of 0.02-0.05mm. The positioning sleeve 3 can rotate axially around the expansion mandrel 1. A blind hole 12 is provided on the left cross-section of the positioning sleeve 3. The diameter of the blind hole 12 is larger than the inner diameter of the positioning sleeve 3. The ends of multiple fan-shaped expansion pieces 2 are inserted into the blind hole 12. Multiple threaded holes 10 are evenly distributed on the annular wall of the blind hole 12. Each fan-shaped expansion piece 2 is provided with a positioning hole 11 corresponding to one of the threaded holes 10. The positioning pin 4 is threadedly fitted with the threaded hole 10 and its end is inserted into the positioning hole 11. The positioning pin 4 prevents the fan-shaped expansion piece 2 from deflecting. The positioning hole 11 and the positioning pin 4 are clearance-fitted, which also facilitates the radial movement and expansion positioning of the fan-shaped expansion piece 2 along the expansion mandrel 1. There are three threaded holes 10 and three positioning holes 11. There are three positioning pins 4. The outer surface of the positioning sleeve 3 is provided with concave and convex textures specially made to increase friction or facilitate gripping, which are used to assist positioning and enhance operational convenience.

[0033] like Figure 3 As shown, the inner diameter of the positioning sleeve 3 is smaller than the outer diameter of the snap ring 5, forming a mechanical stop to prevent the snap ring 5 from axially dislodging. The diameter of the blind hole 12 is larger than the outer diameter of the fan-shaped expansion piece 2 in its free state. Through mechanical interference, the maximum expansion diameter of the fan-shaped expansion piece 2 is limited to be less than or equal to the inner diameter of the blind hole 12. The depth of the blind hole 12 is 0.5-1mm greater than the length of the fan-shaped expansion piece 2 extending into the blind hole 12, ensuring that the fan-shaped expansion piece 2 is not axially constrained when expanding radially. The inner diameter limit of the blind hole 12 takes precedence over the tensile limit of the tension spring 6. When the fan-shaped expansion piece 2 contacts the wall of the blind hole 12, the force on the tension spring 6 drops to a safe value. If the tension spring 6 breaks, the blind hole 12 can still maintain the maximum expansion diameter of the fan-shaped expansion piece 2, preventing the workpiece from flying off.

[0034] In summary, the principle of dynamic adjustment of the expansion shaft size in this invention is as follows: by rotating the expansion mandrel 1, the phase difference between its eccentric arc structure surface 7 and the inner arc surface of the fan-shaped expansion plate 2 drives the outer diameter of the fan-shaped expansion plate 2 to expand, thereby achieving continuous adjustment from the minimum diameter to the maximum diameter. The adjustment range of this invention is as follows: minimum diameter: the outer diameter of the fan-shaped expansion plate 2 after contraction is smaller than the inner diameter of the pipe fitting; maximum diameter: the outer diameter of the fan-shaped expansion plate 2 after full expansion is larger than the inner diameter of the pipe fitting.

[0035] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A purely mechanical expansion shaft, characterized in that, It includes an expansion mandrel (1), multiple fan-shaped expansion pieces (2) evenly distributed around the circumference of the expansion mandrel (1), a positioning sleeve (3) installed at the end of the expansion mandrel (1) and restricting the radial position of the fan-shaped expansion pieces (2), a retaining ring (5) set at both ends of the expansion mandrel (1) to restrict the axial movement of the fan-shaped expansion pieces (2), and a tension spring (6) sleeved on the multiple fan-shaped expansion pieces (2) to restore the inward contraction of the fan-shaped expansion pieces (2); multiple eccentric arc structure surfaces (7) are evenly arranged along the circumference on the outer peripheral wall of the expansion mandrel (1), and the multiple fan-shaped expansion pieces (2) are driven to expand outward or contract inward by the rotation of the eccentric arc structure surface (7) and the contraction force of the tension spring (6).

2. The purely mechanical expansion shaft according to claim 1, characterized in that, The expansion mandrel (1) has a circular end and a hexagonal body (8) at the other end, which can be directly adapted to a standard hexagonal wrench to achieve quick assembly and disassembly and torque transmission.

3. The purely mechanical expansion shaft according to claim 1, characterized in that, Both ends of the expansion mandrel (1) are provided with snap ring grooves, and snap rings (5) are installed in the snap ring grooves; multiple fan-shaped expansion plates (2) are provided with tension spring grooves (9) on their outer peripheral walls, and tension springs (6) are inserted into multiple tension spring grooves (9).

4. The purely mechanical expansion shaft according to claim 1, characterized in that, It also includes a positioning pin (4); the positioning sleeve (3) is clearance-fitted with the expansion mandrel (1), the positioning sleeve (3) can rotate axially around the expansion mandrel (1), the left side section of the positioning sleeve (3) is provided with a blind hole (12), the diameter of the blind hole (12) is larger than the inner diameter of the positioning sleeve (3), the ends of multiple fan-shaped expansion pieces (2) are inserted into the blind hole (12), multiple threaded holes (10) are evenly distributed on the annular hole wall of the blind hole (12), each fan-shaped expansion piece (2) is provided with a positioning hole (11) opposite to one of the threaded holes (10), the positioning pin (4) is threadedly fitted with the threaded hole (10) and its end is inserted into the positioning hole (11).

5. The purely mechanical expansion shaft according to claim 4, characterized in that, The inner diameter of the positioning sleeve (3) is smaller than the outer diameter of the snap ring (5), forming a mechanical stop to prevent the snap ring (5) from axially dislodging. The diameter of the blind hole (12) is larger than the outer diameter of the fan-shaped expansion piece (2) in its free state. Through mechanical interference, the maximum expansion diameter of the fan-shaped expansion piece (2) is limited to be less than or equal to the inner diameter of the blind hole (12). The depth of the blind hole (12) is greater than the length of the fan-shaped expansion piece (2) extending into the blind hole (12).

6. The purely mechanical expansion shaft according to claim 4, characterized in that, Three eccentric arc structure surfaces (7) and three fan-shaped expansion plates (2) are provided. The three eccentric arc structure surfaces (7) are connected end to end. Each eccentric arc structure surface (7) covers the gradual transition from the minimum diameter to the maximum diameter of the expansion mandrel (1). The curved surface connection between two adjacent eccentric arc structure surfaces (7) adopts a rounded transition.

7. The purely mechanical expansion shaft according to claim 6, characterized in that, Three threaded holes (10) and three positioning holes (11) are provided, three positioning pins (4) are provided, and the outer surface of the positioning sleeve (3) is provided with concave and convex textures to increase friction.

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