Puller top rod

Abstract

The application discloses a puller top rod, which comprises a top rod body and a top head. The top rod body is provided with a connecting part at one end and a spherical protrusion at the other end. The top head is provided with a spherical cavity matched with the spherical protrusion and an abutting surface used for abutting against the shaft end of a workpiece. The top rod body is internally provided with a pressure bearing cavity and a pressure bearing part. The pressure bearing part is threadedly matched with the top rod body. When the puller rotates, the pressure bearing part moves along the axial direction and compresses the medium in the pressure bearing cavity. The top head is internally provided with a pressure cavity communicated with the pressure bearing cavity. After being compressed, the medium enters the pressure cavity and clamps the spherical protrusion in the cavity. The puller rotation is used to drive the built-in pressure bearing part to compress the medium to generate hydraulic thrust. On the basis of the mechanical pitch propulsion, the hydraulic auxiliary thrust is superposed to realize the self-adaptive force increase for the large interference fit in the dismounting process.

Description

Technical Field

[0001] This invention relates to the field of mechanical disassembly and assembly tools, specifically to a puller rod. Background Technology

[0002] A puller is a common tool for disassembling motor couplings, pulleys, and bearings. Its working principle is as follows: the puller's claws hook onto the part to be disassembled, and rotating the puller's screw causes the tip to press against the center hole of the shaft, continuing to advance. The screw's rotational motion is converted into linear feed motion, which, through the crossbeam, drives the claws to smoothly pull the part off the shaft. In practice, to reduce labor intensity and improve disassembly efficiency, workers often use tools such as electric wrenches to drive the puller's screw rotation.

[0003] When the component to be disassembled has an interference fit with the shaft and the interference is large, a large axial thrust is required to remove the component. During this process, the tip of the puller screw and the center hole of the shaft end are subjected to huge axial pressure and rotational friction. The tip rotates and rubs continuously within the center hole, which can easily lead to excessive wear, deformation, or even damage to the surface of the center hole (commonly known as "roughening"). Once the center hole is damaged, it will directly affect the positioning accuracy of subsequent shaft parts on the lathe, making it impossible to conduct dynamic balancing tests normally, and in severe cases, even causing the entire rotor to be scrapped. In addition, when disassembling components with large interference fits, the mechanical pushing force of the screw pitch alone is often insufficient to overcome the resistance of the interference fit. Operators need to use auxiliary methods such as heating with a hot gun and tapping, which is not only cumbersome but also prone to causing thermal or impact damage to the shaft and bearings. Summary of the Invention

[0004] This invention provides a puller push rod, which aims to solve the technical problem that when disassembling large interference fit components in existing pullers, the screw tip is easily damaged in the shaft end center hole and the mechanical thrust alone is insufficient to overcome the interference resistance.

[0005] To achieve the above objectives, the puller rod provided by the present invention includes a puller rod body and a mandrel. One end of the puller rod body is provided with a connecting portion, and the other end is provided with a spherical protrusion. One end of the mandrel is provided with a spherical cavity adapted to the spherical protrusion, the spherical protrusion being rotatably embedded in the spherical cavity. The other end of the mandrel is provided with an abutment surface for abutting against the end face of the workpiece shaft. A pressure-bearing cavity is provided within the puller rod body, and a pressure-bearing component is provided within the pressure-bearing cavity. The pressure-bearing component is threadedly engaged with the puller rod body. When the puller rod body rotates, the pressure-bearing component moves axially and compresses the medium within the pressure-bearing cavity. A pressure chamber is provided within the mandrel, and the pressure chamber communicates with the pressure-bearing cavity.

[0006] Furthermore, a guide hole is provided on the spherical cavity, and the pressure chamber is connected to the pressure chamber through the guide hole.

[0007] Furthermore, the pressure chamber, the guide hole, and the pressure chamber together form a sealed volume chamber, which is filled with an incompressible medium.

[0008] Furthermore, the incompressible medium is hydraulic oil or grease.

[0009] Furthermore, the pressure-bearing component is a piston, with a through hole in the center of the piston for the puller screw to pass through, and a sealing ring is provided between the outer circumferential surface of the piston and the inner wall surface of the pressure-bearing cavity.

[0010] Furthermore, the inner wall of the pressure-bearing cavity is provided with internal threads, and the outer circumferential surface of the pressure-bearing component is provided with external threads that mate with the internal threads.

[0011] Furthermore, it also includes a limiting component, which is disposed on the top head and limits the axial extension distance of the top head.

[0012] Furthermore, the limiting component includes an annular limiting boss and a limiting ring. The annular limiting boss is disposed on the outer peripheral surface of the top rod body, and the limiting ring is fixed to the inner wall surface of the top head.

[0013] Furthermore, an annular sealing groove is formed on the spherical protrusion, and a sealing ring is provided inside the annular sealing groove.

[0014] Furthermore, the connecting part has an external hexagonal head, and the contact surface is a flat surface.

[0015] Compared with the prior art, the present invention has the following advantages: This invention achieves a combined mechanical propulsion and hydraulic assistance drive by incorporating a pressure-bearing chamber and a pressure-bearing component within the push rod body, and utilizing the rotational motion of the push rod itself to drive the pressure-bearing component to compress the medium and generate hydraulic thrust. Compared to traditional pullers that rely solely on mechanical pitch feed, this invention can provide a greater axial disassembly force under the same rotational torque, making it particularly suitable for disassembling components with large interference fits.

[0016] This invention utilizes a ball joint connection structure between the spherical protrusion and the spherical cavity between the push rod body and the push head, ensuring no relative rotation between the push head and the central hole at the shaft end, thus avoiding frictional damage to the central hole at the shaft end. At the same time, the ball joint structure allows for angle self-adaptation, ensuring that the contact surface and the shaft end surface always remain in contact, resulting in uniform force distribution and preventing damage to the workpiece due to excessive local pressure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the puller rod shown in this invention.

[0018] Figure 2 This is one of the schematic diagrams of the internal structure of the puller rod shown in this invention.

[0019] Figure 3 This is the second schematic diagram of the internal structure of the puller rod shown in this invention.

[0020] Figure label: 1-Top rod body; 2-Connecting part; 3-Spherical protrusion; 4-Top head; 5-Spherical cavity; 6-Abutting surface; 7-Pressure chamber; 8-Pressure bearing component; 9-Sealing ring; 10-Limiting ring; 11-External hexagonal head. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of this application and not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0022] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] Figures 1 to 3 A schematic structural diagram of the puller rod according to an embodiment of the present invention is shown. Figures 1 to 3 As shown, the puller rod includes a puller body 1 and a head 4. One end of the puller body 1 has a connecting part 2, and the other end has a spherical protrusion 3. One end of the head 4 has a spherical cavity 5 that matches the spherical protrusion 3, with the spherical protrusion 3 embedded within the cavity 5. The other end of the head 4 has an abutment surface 6. A pressure-bearing cavity 7 is provided inside the puller body 1, and a pressure-bearing component 8 is provided within the cavity 7, threadedly engaged with the puller body 1. When the puller rod rotates, it advances axially, and the end of the puller rod abuts against the pressure-bearing component 8, pushing it to move axially and compressing the medium within the pressure-bearing cavity 7. A pressure chamber is provided inside the head 4, communicating with the pressure-bearing cavity 7. When the medium is pressurized, it enters the pressure chamber and acts on the inner wall of the spherical cavity 5, driving the cavity 5 to clamp the spherical protrusion 3.

[0025] In this embodiment of the invention, the puller rod is applied to the disassembly of large interference fit components (such as couplings, pulleys, and bearings) in the field of mechanical repair. The puller rod is installed at the end of the puller screw, and the contact surface 6 of the jack 4 abuts against the end face of the workpiece shaft. The operator rotates the puller screw, and the puller screw advances axially. On the one hand, the mechanical thrust is transmitted to the end face of the workpiece shaft through the puller rod, and on the other hand, an auxiliary thrust is generated by the internal hydraulic self-pressurizing mechanism. This achieves efficient disassembly of large interference fits while protecting the center hole of the shaft end.

[0026] When disassembling large interference fit components, existing puller rods subject the center point and shaft end center hole to enormous axial pressure and rotational friction, easily leading to wear and deformation of the center hole. Adding a freely rotating mandrel at the end of the puller rod, preventing the mandrel from rotating with the puller rod, can reduce frictional damage to the center hole to some extent. However, as the interference fit increases, mechanical pitch thrust alone is insufficient to overcome the interference resistance, requiring operators to use auxiliary methods such as heating with a heat gun. If a self-pressurizing mechanism is integrated inside the puller rod, using the axial thrust of the puller screw to drive the internal medium and generate hydraulic thrust, a combined driving effect can be achieved while protecting the center hole.

[0027] like Figures 1 to 3 As shown, the puller rod includes a puller body 1 and a head 4. One end of the puller body 1 has a connecting part 2, and the other end has a spherical protrusion 3. The connecting part 2 is an external hexagonal head 11, used to engage with a wrench to fix the puller rod to the end of the puller screw, preventing the puller body 1 from rotating relative to the puller screw. An axially oriented pressure-bearing cavity 7 is formed inside the puller body 1. The pressure-bearing cavity 7 is a cylindrical cavity with internal threads on its inner wall. A pressure-bearing component 8 is disposed within the pressure-bearing cavity 7. The outer circumferential surface of the pressure-bearing component 8 has external threads that mate with the internal threads on the inner wall of the pressure-bearing cavity 7. The pressure-bearing component 8 and the puller body 1 are threadedly engaged. The puller screw passes through the through hole in the center of the pressure-bearing component 8 and abuts against the head 4. When the puller screw rotates and advances, the end of the puller screw abuts against and pushes the pressure-bearing component 8. Under the action of the threaded engagement, the pressure-bearing component 8 moves axially, compressing the medium within the pressure-bearing cavity 7. The pressure-bearing component 8 is in the form of a piston, with a through hole in the center for the puller screw to pass through. A sealing ring 9 is provided between the outer circumferential surface of the piston and the inner wall surface of the pressure-bearing chamber 7 to prevent leakage of the medium in the pressure-bearing chamber 7.

[0028] A spherical protrusion 3 is located at the end of the push rod body 1 away from the connecting part 2. An annular sealing groove is formed on the spherical surface of the spherical protrusion 3, and a sealing ring 9 is installed inside the annular sealing groove. A guide hole is also formed on the spherical cavity 5, with one end opening onto the spherical surface of the spherical protrusion 3 and the other end communicating with the pressure-bearing cavity 7. The push head 4 is a sleeve-shaped component, with a spherical cavity 5 at one end that matches the spherical protrusion 3. The spherical protrusion 3 is embedded in the spherical cavity 5, forming a ball-and-socket connection structure. The other end of the push head 4 has an abutment surface 6, which is a flat surface used to abut against the end face of the workpiece shaft. A pressure chamber is provided inside the push head 4, located between the spherical cavity 5 and the abutment surface 6. The guide hole connects the pressure-bearing cavity 7 to the pressure chamber.

[0029] The pressure chamber 7, the guide hole, and the pressure chamber together form a sealed volumetric cavity, which is filled with an incompressible medium, namely hydraulic oil or lubricating grease. The sealed volumetric cavity is sealed and isolated from the external environment by the sealing ring 9 on the spherical surface of the spherical protrusion 3 and the sealing ring 9 on the outer circumference of the piston.

[0030] A limiting component is also provided between the mandrel 4 and the mandrel body 1. The limiting component is used to limit the axial extension distance of the mandrel 4 relative to the mandrel body 1. The limiting component includes an annular limiting boss and a limiting ring 10. The annular limiting boss is located on the outer circumferential surface of the mandrel body 1, behind the spherical protrusion 3. The limiting ring 10 is fixed to the inner wall surface of the mandrel 4, and the inner diameter of the limiting ring 10 is smaller than the outer diameter of the annular limiting boss. When the mandrel 4 extends outward to its limit position relative to the mandrel body 1, the limiting ring 10 axially abuts against the annular limiting boss, preventing the mandrel 4 from extending further.

[0031] In this embodiment of the invention, the puller screw passes through the pressure-bearing member 8 and abuts against the mandrel 4. When the puller screw rotates and advances, the end of the puller screw directly abuts against and pushes the pressure-bearing member 8. Under the action of the threaded engagement, the pressure-bearing member 8 moves axially to compress the medium. Therefore, the rotational advancing motion of the puller screw transmits mechanical thrust to the end face of the workpiece shaft; pushing the pressure-bearing member 8 to compress the medium generates hydraulic auxiliary thrust.

[0032] The working principle of this invention is as follows: The operator hooks the puller's claws onto the part to be disassembled, and installs the puller's push rod at the end of the puller's screw, so that the contact surface 6 of the pusher head 4 abuts against the end face of the workpiece shaft. When the puller's screw is rotated using a wrench or electric wrench, the puller's screw advances axially. After the end of the puller's screw passes through the through hole of the pressure bearing member 8, it abuts against the pusher head 4, pushing the pusher head 4 to transmit mechanical thrust to the end face of the workpiece shaft. At the same time, the end of the puller's screw also abuts against and pushes the pressure bearing member 8. Since the pressure bearing member 8 and the pusher body 1 are threadedly fitted, the pressure bearing member 8 moves axially to compress the incompressible medium in the pressure bearing cavity 7. After being pressurized, the medium enters the pressure cavity of the pusher head 4 through the guide hole on the spherical protrusion 3. The hydraulic pressure acts on the inner wall of the spherical concave cavity 5 of the pusher head 4, driving the spherical concave cavity 5 to clamp the spherical protrusion 3. Because the spherical protrusion 3 and the spherical cavity 5 are in a spherical fit, the clamping force generated by the medium pressure is evenly distributed on the spherical surface, making the ball joint connection between the mandrel 4 and the mandrel body 1 tighter and more reliable, thus preventing the mandrel 4 from loosening or wobbling when subjected to large axial loads. At the same time, this clamping force does not hinder the swing adjustment of the mandrel 4 relative to the mandrel body 1, and the automatic self-aligning function of the ball joint connection is retained.

[0033] Furthermore, the greater the interference fit of the component to be disassembled and the greater the rotational torque applied by the operator, the greater the thrust of the puller screw on the pressure bearing 8, the greater the compression of the medium by the pressure bearing 8, the higher the medium pressure, and the greater the clamping force of the spherical cavity 5 on the spherical protrusion 3. Consequently, the rigidity and stability of the ball joint connection are enhanced. In other words, the self-pressurizing capability of the puller screw is positively correlated with the interference fit of the component to be disassembled, achieving an adaptive effect of "the greater the interference fit, the stronger the clamping." At the same time, the hydraulic auxiliary thrust also increases accordingly, assisting in the disassembly of the interference fit components.

[0034] To verify the technical effects of the embodiments of the present invention, specific examples are described in detail below.

[0035] In this embodiment, the length of the push rod body 1 is 150mm, the diameter of the pressure-bearing cavity 7 is 30mm, the stroke of the pressure-bearing component 8 is 20mm, and the initial volume of the sealed volume cavity is 14000mm². 3 The compressed volume is 11200 mm². 3 The volume compression rate is 20%. The diameter of the piston center through hole is 16mm, which is compatible with an M16 puller screw. The diameter of the spherical protrusion 3 is 25mm, and the diameter of the contact surface 6 is 50mm.

[0036] The thrust test and the center hole protection effect test were conducted on the pull rod with the above structure.

[0037] During testing, the puller rod was installed at the end of the puller screw, and the puller pawls were fixed to the pull ring of the force gauge. The maximum disassembly force was tested under two conditions: simple mechanical propulsion and mechanical propulsion with hydraulic assistance. A torque wrench was used to control the input torque at 50 N·m.

[0038] Test results show that the maximum dismantling force of a conventional puller rod under an input torque of 50 N·m is 15 kN. The puller rod of this invention, under the same input torque, has a maximum dismantling force of 25 kN, representing a force increase of approximately 67%. This demonstrates that the self-pressurizing mechanism of the puller rod in this embodiment of the invention effectively generates hydraulically assisted thrust.

[0039] When testing the protection effect of the center hole, a motor shaft of the same specification was used, and a simulated disassembly test was conducted using a traditional push rod and the puller push rod of the present invention. Each test was performed 20 times, and the surface condition of the inner wall of the center hole was observed using a microscope.

[0040] Test results show that after 20 simulated disassembly cycles using a traditional puller, obvious wear marks and indentations appeared on the inner wall of the center hole, with a roundness deviation of 0.05mm to 0.08mm, failing to meet the lathe positioning accuracy requirements. After 20 simulated disassembly cycles using the puller puller of this invention, the inner wall surface of the center hole remained intact, and the roundness deviation was less than 0.01mm, meeting the lathe positioning accuracy requirements. This indicates that the puller puller of this invention effectively protects the shaft end center hole while providing greater disassembly force.

[0041] The puller rod of this invention was used in an actual maintenance site for disassembling couplings. The coupling to be disassembled had an interference fit with the motor shaft, with an interference of 0.06 mm and a shaft diameter of 80 mm. Traditional methods require heating to over 150°C with a heating gun for approximately 20 minutes, and there is a risk of thermal deformation. Using the puller rod of this invention, under normal temperature conditions, the operator uses an electric wrench to drive the process, which takes approximately 5 minutes. The coupling is smoothly removed, the center hole at the shaft end is intact, and the coupling shows no thermal deformation and can be directly reused.

[0042] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A puller rod, characterized in that, include: The top rod body (1) has a connecting part (2) at one end and a spherical protrusion (3) at the other end. Top head (4), one end of the top head (4) is provided with a spherical cavity (5) adapted to the spherical protrusion (3), the spherical protrusion (3) is embedded in the spherical cavity (5), and the other end of the top head (4) is provided with an abutment surface (6). The top rod body (1) is provided with a pressure-bearing cavity (7), and a pressure-bearing component (8) is provided in the pressure-bearing cavity (7). The pressure-bearing component (8) is threadedly engaged with the top rod body (1). When the top rod body (1) rotates, the pressure-bearing component (8) moves axially and compresses the medium in the pressure-bearing cavity (7). The top head (4) is provided with a pressure chamber, which is connected to the pressure bearing chamber (7).

2. The puller rod according to claim 1, characterized in that, The spherical cavity (5) is provided with a flow guide hole, and the pressure bearing cavity (7) is connected to the pressure cavity through the flow guide hole.

3. The puller rod according to claim 1, characterized in that, The pressure chamber (7), the guide hole and the pressure chamber together form a sealed volume chamber, which is filled with an incompressible medium.

4. The puller rod according to claim 3, characterized in that, The incompressible medium is hydraulic oil or lubricating grease.

5. The puller rod according to claim 1, characterized in that, The pressure-bearing component (8) is a piston, and a through hole is provided in the center of the piston. A sealing ring (9) is provided between the outer peripheral surface of the piston and the inner wall surface of the pressure-bearing cavity (7).

6. The puller rod according to claim 1, characterized in that, The inner wall of the pressure-bearing cavity (7) is provided with an internal thread, and the outer circumferential surface of the pressure-bearing component (8) is provided with an external thread that mates with the internal thread.

7. The puller rod according to claim 1, characterized in that, It also includes a limiting component, which is disposed between the top head (4) and the top rod body (1) and limits the axial extension distance of the top head (4).

8. The puller rod according to claim 7, characterized in that, The limiting component includes an annular limiting boss and a limiting ring (10). The annular limiting boss is disposed on the outer peripheral surface of the top rod body (1), and the limiting ring (10) is fixed to the inner wall surface of the top head (4).

9. The puller rod according to claim 1, characterized in that, An annular sealing groove is provided on the spherical surface of the spherical protrusion (3), and a sealing ring (9) is provided in the annular sealing groove.

10. The puller rod according to claim 1, characterized in that, The connecting part (2) is an external hexagonal head (11), and the abutting surface (6) is a plane.

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