Bidirectional tensioning mechanism for special-shaped pipe

Abstract

The utility model discloses a special pipe two-way tensioning mechanism and belongs to the technical field of automobile steering transmission shaft machining. The device comprises an internal expansion mandrel, an expansion sleeve, a pull expansion screw and a rotation stopping discharging pin, the internal expansion mandrel is installed on a machine tool spindle through a cylindrical step and a screw installation hole, and the expansion sleeve is installed on an internal expansion conical surface and a first transition cylindrical surface of the internal expansion mandrel in a sleeved mode through an external expansion conical surface and a second transition cylindrical surface. The appearance of the tensioning sleeve is matched with an inner cavity of a special-shaped pipe, the pull-expansion screw penetrates through a step through hole in the internal-expansion mandrel and is connected with a machine tool pull rod through an external thread structure, and the rotation-stopping discharging pin penetrates through the tensioning sleeve, the internal-expansion mandrel and the pull-expansion screw in the radial direction at the same time and is connected with the machine tool pull rod through an external thread structure. And the internal expansion mandrel, the expansion sleeve and the tension screw do not generate relative rotation. According to the utility model, higher workpiece centering precision and tensioning retention force can be provided.

Description

Technical Field

[0001] This utility model belongs to the field of automotive steering drive shaft processing technology, specifically relating to a bidirectional tensioning mechanism for a special-shaped tube. Background Technology

[0002] The automotive steering driveshaft is a crucial component of the automotive steering system, serving two functions: torque transmission and telescopic adjustment. The driveshaft connects to the steering column and steering gear at opposite ends, forming a specific spatial angle. Due to inherent deviations in the actual vehicle installation and manufacturing process of the driveshaft, a certain degree of runout occurs during torsion, leading to accelerated wear of the driveshaft and its associated components, reducing their lifespan. Therefore, controlling the runout within a reasonable range is paramount. Reducing the runout of the driveshaft primarily involves controlling the dimensional and positional deviations between the inner cavity and the machined surface of its key component, the shaped tube. Traditional clamping methods typically involve directly holding the outer diameter of the shaped tube with chuck jaws. However, the inner cavity and outer diameter of the shaped tube have forming errors, making it difficult to guarantee the dimensional and positional deviations between the inner cavity and the machined surface during actual machining. Utility Model Content

[0003] This invention addresses the aforementioned problems and overcomes the shortcomings of existing technologies by providing a bidirectional tensioning mechanism for irregularly shaped tubes. This invention can provide higher workpiece centering accuracy and tension holding force.

[0004] To achieve the above objectives, the present invention adopts the following technical solution.

[0005] This utility model provides a bidirectional tensioning mechanism for irregularly shaped tubes, including an inner expansion mandrel, a tensioning sleeve, a tensioning screw, and an anti-rotation unloading pin. The inner expansion mandrel is mounted on a machine tool spindle via a cylindrical step and a screw mounting hole. The tensioning sleeve is fitted onto the inner expansion conical surface and the first transition cylindrical surface of the inner expansion mandrel via an outer expansion conical surface and a second transition cylindrical surface. The outer shape of the tensioning sleeve matches the inner cavity of the irregularly shaped tube. The tensioning screw passes through a stepped through-hole in the inner expansion mandrel and is connected to the machine tool tie rod via an external thread structure. The anti-rotation unloading pin simultaneously passes radially through the tensioning sleeve, the inner expansion mandrel, and the tensioning screw, preventing relative rotation between the inner expansion mandrel, the tensioning sleeve, and the tensioning screw.

[0006] Furthermore, one end of the inner expansion mandrel is provided with an inner expansion conical surface, a first transition cylindrical surface, and another inner expansion conical surface in sequence along the axial direction. The two inner expansion conical surfaces are in the same direction and have the same conical angle. A first waist-shaped through hole is provided on the first transition cylindrical surface for the anti-rotation unloading pin to pass through. The other end of the inner expansion mandrel is provided with a cylindrical step. Three evenly distributed screw mounting holes are provided on the cylindrical step. The step through hole is provided through the inner expansion mandrel along the axial direction.

[0007] Furthermore, the tensioning sleeve adopts a ball track shaft structure. Both ends of the tensioning sleeve are respectively provided with elongated slots of the same number and size as the ball tracks. The outer expansion cone surfaces are respectively provided on both sides of the inner cavity of the tensioning sleeve. The cone angle of the two outer expansion cone surfaces is the same as the angle of the two inner expansion cone surfaces of the inner expansion mandrel. The second transition cylindrical surface is provided between the two outer expansion cone surfaces in the inner cavity of the tensioning sleeve. The second transition cylindrical surface is provided with a cylindrical through hole for the anti-rotation unloading pin to pass through.

[0008] Furthermore, one end of the tension screw is provided with an internal hexagonal clamping boss, the middle of the tension screw is a third transition cylindrical surface, the third transition cylindrical surface is provided with a second waist-shaped through hole of the same size and specification as the first waist-shaped through hole for passing through the anti-rotation unloading pin, and the other end of the tension screw is provided with the external thread structure.

[0009] Furthermore, the first transition cylindrical surface and the second transition cylindrical surface are fitted with a clearance fit, and the third transition cylindrical surface and the stepped through hole are fitted with a clearance fit.

[0010] Furthermore, the anti-rotation unloading pin is configured as a cylindrical pin.

[0011] The beneficial effects of this utility model.

[0012] This utility model has a simple structure, high positioning accuracy, reliability and clamping efficiency, and is easy to operate. The bidirectional tensioning structure provides higher workpiece centering accuracy and tensioning retention force. At the same time, the use of anti-rotation unloading pins can effectively avoid workpiece slippage caused by insufficient tensioning force and difficulties in releasing tensioning from small-angle conical surfaces, which are detrimental to workpiece loading and unloading. Attached Figure Description

[0013] To make the technical problems solved, the technical solutions, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0014] Figure 1 This is a schematic diagram of the overall cross-sectional structure of this utility model.

[0015] Figure 2 This is a cross-sectional structural diagram of the internal expansion mandrel of this utility model.

[0016] Figure 3 This is a cross-sectional structural diagram of the tensioning sleeve of this utility model.

[0017] Figure 4 This is a side view of the tensioning sleeve of this utility model.

[0018] Figure 5 This is a cross-sectional structural diagram of the tension screw of this utility model.

[0019] The markings in the diagram are as follows: 1 is the inner expansion mandrel, 2 is the tensioning sleeve, 3 is the tensioning screw, 4 is the stop and unloading pin, 5 is the cylindrical step, 6 is the screw mounting hole, 7 is the inner expansion conical surface, 8 is the first transition cylindrical surface, 9 is the outer expansion conical surface, 10 is the second transition cylindrical surface, 11 is the stepped through hole, 12 is the external thread structure, 13 is the first waist-shaped through hole, 14 is the ball track shaft structure, 15 is the long groove, 16 is the cylindrical through hole, 17 is the internal hexagonal clamping boss, 18 is the third transition cylindrical surface, and 19 is the second waist-shaped through hole. Detailed Implementation

[0020] As shown in the accompanying drawings, this embodiment provides a bidirectional tensioning mechanism for irregularly shaped tubes, including an inner expansion mandrel 1, a tensioning sleeve 2, a tensioning screw 3, and an anti-rotation unloading pin 4.

[0021] One end of the internal expansion mandrel 1 is provided with an internal expansion conical surface 7, a first transition cylindrical surface 8 and another internal expansion conical surface 7 in sequence along the axial direction. The two internal expansion conical surfaces 7 are in the same direction and have the same conical angle. A first waist-shaped through hole 13 is provided on the first transition cylindrical surface 8. The other end of the internal expansion mandrel 1 is provided with a cylindrical step 5. Three evenly distributed screw mounting holes 6 are provided on the cylindrical step 5. It is installed on the machine tool spindle through the cylindrical step 5 and the screw mounting holes 6. A stepped through hole 11 is provided through the internal expansion mandrel 1 along the axial direction.

[0022] The inner expansion mandrel 1 is made of mold steel, grade Cr12MoV, and is heat-treated to meet certain hardness requirements.

[0023] The expansion sleeve 2 is matched with the inner cavity of the irregular tube. The expansion sleeve 2 adopts a ball track shaft structure 14. The two ends of the expansion sleeve 2 are respectively provided with long slots 15 with the same number and size as the ball tracks. The inner cavity of the expansion sleeve 2 is provided with outer expansion cone surfaces 9 on both sides. The cone angle of the two outer expansion cone surfaces 9 is the same as the angle of the two inner expansion cone surfaces 7 of the inner expansion mandrel 1. The second transition cylindrical surface 10 is provided between the two outer expansion cone surfaces 9 in the inner cavity of the expansion sleeve 2. The second transition cylindrical surface 10 is provided with a cylindrical through hole 16. The expansion sleeve 2 is fitted onto the inner expansion cone surface 7 and the first transition cylindrical surface 8 of the inner expansion mandrel 1 through the outer expansion cone surface 9 and the second transition cylindrical surface 10. The first transition cylindrical surface 8 and the second transition cylindrical surface 10 adopt a clearance fit.

[0024] The tensioning sleeve 2 is made of spring steel, grade 65Mn, and is heat-treated to meet certain requirements for hardness, elastic contraction and release.

[0025] The tension screw 3 passes through the stepped through hole 11 inside the inner expansion mandrel 1. One end of the tension screw 3 is provided with an internal hexagonal clamping boss 17. The middle of the tension screw 3 is a third transition cylindrical surface 18. The third transition cylindrical surface 18 and the stepped through hole 11 are fitted with clearance. The third transition cylindrical surface 18 is provided with a second waist-shaped through hole 19 of the same size and specification as the first waist-shaped through hole 13. The other end of the tension screw 3 is provided with an external thread structure 12, which is connected to the machine tool tie rod through the external thread structure 12.

[0026] The anti-rotation unloading pin 4 is set as a cylindrical pin. The anti-rotation unloading pin 4 passes radially through the cylindrical through hole 16 of the tension sleeve 2, the first waist-shaped through hole 13 of the inner expansion mandrel 1, and the second waist-shaped through hole of the tension screw 3, so that the inner expansion mandrel 1, the tension sleeve 2, and the tension screw 3 do not rotate relative to each other.

[0027] The operating principle is as follows: The shaped tube is fitted onto the tensioning sleeve 2, which adopts a ball bearing structure 14. The machine tool pull rod drives the tensioning screw 3, causing the internal hexagonal clamping boss 17 to contact the tensioning sleeve 2 and simultaneously drive the tensioning sleeve 2 and the anti-rotation unloading pin 4 to perform axial tensioning action. During the tensioning process, the anti-rotation unloading pin 4 always maintains non-contact sliding with the first waist-shaped through hole 13 and the two ends of the second waist-shaped through hole. The inner expansion cone surface 7 squeezes the outer expansion cone surface 9, causing the long slot 15 of the tensioning sleeve 2 to produce elastic deformation, thus tightening and locking the shaped tube.

[0028] When the machine tool pull rod drives the tension screw 3 to push and release, firstly, the internal hexagonal clamping boss 17 of the tension screw 3 disengages from the tension sleeve 2. Then, the tension screw 3 continues to push and release, and the second oblong through hole 19 contacts the anti-rotation unloading pin 4, causing the inner expansion cone 7 and the outer expansion cone 9 to completely disengage. The long groove 15 elastically deforms and recovers, and the tensioning force applied to the special-shaped tube is released.

[0029] It is understood that the above specific description of this utility model is only used to illustrate this utility model and is not limited to the technical solutions described in the embodiments of this utility model. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to this utility model to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of this utility model.

Claims

1. A bidirectional tensioning mechanism for a special-shaped tube, comprising an inner expansion mandrel (1), a tensioning sleeve (2), a tensioning screw (3), and an anti-rotation unloading pin (4), characterized in that, The inner expansion mandrel (1) is installed on the machine tool spindle through the cylindrical step (5) and screw mounting hole (6). The tensioning sleeve (2) is fitted on the inner expansion conical surface (7) and the first transition cylindrical surface (8) of the inner expansion mandrel (1) through the outer expansion conical surface (9) and the second transition cylindrical surface (10). The outer shape of the tensioning sleeve (2) matches the inner cavity of the shaped tube. The tensioning screw (3) passes through the stepped through hole (11) in the inner expansion mandrel (1) and is connected to the machine tool tie rod through the external thread structure (12). The anti-rotation unloading pin (4) passes radially through the tensioning sleeve (2), the inner expansion mandrel (1) and the tensioning screw (3) to prevent relative rotation of the inner expansion mandrel (1), the tensioning sleeve (2) and the tensioning screw (3).

2. The bidirectional tensioning mechanism for irregularly shaped tubes according to claim 1, characterized in that, One end of the inner expansion mandrel (1) is provided with an inner expansion conical surface (7), a first transition cylindrical surface (8) and another inner expansion conical surface (7) in sequence along the axial direction. The two inner expansion conical surfaces (7) are in the same direction and have the same conical angle. The first transition cylindrical surface (8) is provided with a first waist-shaped through hole (13) for passing through the anti-rotation unloading pin (4). The other end of the inner expansion mandrel (1) is provided with a cylindrical step (5). The cylindrical step (5) is provided with three evenly distributed screw mounting holes (6). The step through hole (11) is provided through the inner expansion mandrel (1) along the axial direction.

3. The bidirectional tensioning mechanism for irregularly shaped tubes according to claim 2, characterized in that, The tensioning sleeve (2) adopts a ball track shaft structure (14). The tensioning sleeve (2) has long slots (15) with the same number and size as the ball tracks at both ends. The outer expansion cones (9) are respectively set on both sides of the inner cavity of the tensioning sleeve (2). The cone angle of the two outer expansion cones (9) is the same as the angle of the two inner expansion cones (7) of the inner expansion mandrel (1). The second transition cylindrical surface (10) is set between the two outer expansion cones (9) in the inner cavity of the tensioning sleeve (2). The second transition cylindrical surface (10) is provided with a cylindrical through hole (16) for passing through the anti-rotation unloading pin (4).

4. The bidirectional tensioning mechanism for irregularly shaped tubes according to claim 3, characterized in that, One end of the tension screw (3) is provided with an internal hexagonal clamping boss (17), the middle of the tension screw (3) is a third transition cylindrical surface (18), the third transition cylindrical surface (18) is provided with a second waist-shaped through hole (19) of the same size and specification as the first waist-shaped through hole (13) for passing through the anti-rotation unloading pin (4), and the other end of the tension screw (3) is provided with the external thread structure (12).

5. The bidirectional tensioning mechanism for irregularly shaped tubes according to claim 4, characterized in that, The first transition cylindrical surface (8) and the second transition cylindrical surface (10) are fitted with a clearance fit, and the third transition cylindrical surface (18) and the stepped through hole (11) are fitted with a clearance fit.

6. The bidirectional tensioning mechanism for irregularly shaped tubes according to claim 5, characterized in that, The anti-rotation unloading pin (4) is set as a cylindrical pin.

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