A combined expansion clamping device for fixing a shaft

Abstract

This invention provides a combined expansion and tightening device for fixing a shaft, relating to the field of mechanical component technology. It includes a shaft core with a vent hole at its center and a recessed fitting groove around its periphery. An expansion strip is detachably connected to the fitting groove, and the fitting groove has an air outlet. The expansion strip includes a fitting strip and a felt strip. The fitting strip has air inlets corresponding to the air outlets. The advantage of this invention is that by introducing pressurized gas into the vent hole, the felt strip rapidly expands radially outward under pressure, forming a tight contact with the inner wall of the mechanical expander, achieving immediate locking. After releasing the pressure, the felt strip automatically contracts under its own elastic restoring force, and the mechanical expander returns to a free-rotating state. This process requires no manual intervention, has a fast response speed, facilitates automated control and rapid roll changing, and significantly improves production efficiency.

Description

Technical Field

[0001] This invention relates to the field of mechanical parts technology, and in particular to a combined expansion and tightening device for fixing a shaft. Background Technology

[0002] In winding and unwinding equipment used in industries such as roll forming, printing and packaging, textiles and papermaking, the fixed connection between the shaft and the roll core is crucial for stable winding and unwinding operations. To meet the demands of rapid roll changes and reliable transmission, the industry widely employs expansion structures to achieve a keyless connection between the shaft and the roll core. Common expansion structures include air shafts, mechanical expansion sleeves, and hydraulic expansion devices.

[0003] To prevent accidental rotation of the mechanical expander relative to the shaft core, existing technologies typically employ key connections, screw locking, or end-face clamping for circumferential fixation. However, key connections require machining keyways on both the shaft core and the mechanical expander, increasing manufacturing costs and posing inconvenience during installation due to the need for precise alignment. Screw locking or end-face clamping methods require specialized tools for tightening and loosening, necessitating repeated operations during roll changes and reducing production efficiency.

[0004] When subjected to high-speed rotation or impact loads, screw connections are prone to loosening, and the frictional force of end face clamping may also be attenuated due to vibration, causing relative slippage between the mechanical expander and the shaft core, affecting the reliability of expansion and fixing.

[0005] Traditional locking methods typically require manual intervention to lock or unlock, making it impossible to achieve automated, real-time control and difficult to meet the needs of automated production lines for rapid roll changes and remote control.

[0006] Creating keyways or threaded holes weakens the structural strength of the shaft and mechanical expander, especially when the shaft diameter is small or the wall thickness is thin. This effect is more significant and may lead to fatigue fracture of the shaft during use. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides a combined expansion and tightening device for fixing the shaft. By introducing pressurized gas into the vent, the felt strip rapidly expands radially outward under the action of air pressure, forming a tight contact with the inner wall of the mechanical expander, achieving instant locking. After releasing the air pressure, the felt strip automatically contracts under its own elastic restoring force, and the mechanical expander returns to a free rotation state. This process requires no manual intervention, has a fast response speed, facilitates automated control and rapid roll changing, and greatly improves production efficiency.

[0008] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A combined expansion and tightening device for fixing a shaft includes a shaft core, a vent hole at the center of the shaft core, and a fitting groove recessed towards the inside of the shaft core around the periphery of the shaft core. The fitting groove is detachably connected to an expansion strip, and the fitting groove is provided with an air outlet; the expansion strip includes a fitting strip and a felt strip; the fitting strip is provided with an air supply hole corresponding to the air outlet; when pressurized gas is introduced into the vent, the gas flows through the vent, the air outlet, and the air supply hole in sequence, and finally reaches the felt strip, causing the felt strip to expand radially outward under the action of air pressure, thereby increasing its volume and forming a tight contact with the inner wall of the mechanical expander sleeved on the outside of the shaft core, generating friction or mechanical locking force, so that the mechanical expander is locked and cannot rotate relative to the shaft core; The mechanical expander includes a ring body, which is an annular structure. Several expansion blocks are movably connected to the ring body. The expansion blocks are evenly distributed along the circumference of the ring body and are used to extend outward or retract inward in the radial direction to achieve tightening and locking or unlocking with external components.

[0009] Furthermore, the ring body is provided with a number of expansion block slots, each expansion block slot corresponding to accommodate one expansion block; the bottom of the expansion block slot is semi-circular arc-shaped, which is used to form a rotational fit with the semi-circular arc bottom of the expansion block, so that the expansion block can swing around the center of the semi-circular arc bottom in the expansion block slot. The other end of the expansion block is provided with a top head, which is the free end of the expansion block and is used to protrude from the circumferential surface of the ring body when the expansion block swings outward, and abut against the inner wall of the external component to achieve expansion and locking. The first opening of the expansion block groove is located on the circumferential wall of the ring body, so that the expansion block groove communicates with the outside of the ring body; When the expansion block rotates in the first direction, the top head is hidden inside the ring body. At this time, the expansion and tightening structure is in a contracted state, and the external components can be freely installed and removed. When the expansion block rotates in the second direction, the top protrudes beyond the circumference of the ring body. At this time, the expansion block abuts against the inner wall of the external component to achieve expansion and locking. A reset spring bar is embedded inside the ring body, and the reset spring bar has a spring force that drives the expansion block to rotate in the second direction.

[0010] Furthermore, the second opening of the expansion block groove communicates with one side of the ring body; this side is the axial end face of the ring body; The expansion block groove is provided with a first side opening and a second side opening on both sides respectively; the first side opening and the second side opening are both clearance spaces extending outward from the side wall of the expansion block groove, and their opening direction is consistent with the direction of the second opening, which are used to provide clearance space for the expansion block during rotation and prevent the expansion block from interfering with the ring body. A rotating cavity is provided near the circumference of the ring body at the second side opening. The rotating cavity is an arc-shaped or hemispherical cavity formed by the inward indentation from the second side opening. When the expansion block rotates in the first direction under the action of external driving force, the top head swings towards the first side opening; at the same time, the semi-circular bottom swings towards the second side opening, and the upper end of the semi-circular bottom gradually fits into the rotating receiving cavity, so that the expansion block can obtain a larger rotation angle, thereby realizing that the top head is completely retracted into the ring body and releasing the expansion locking state.

[0011] Furthermore, a first observation window is provided on the side of the ring body away from the second side opening. The first observation window is a through window structure formed by a recess inward from the end face of the ring body, and its position corresponds to the second side opening in the radial direction. A partition wall is maintained between the first observation window and the expansion block groove to prevent the reset spring bar from coming out of the first observation window. A second observation window is provided on the side of the ring body away from the first side opening. The second observation window is a through window structure formed by a recess inward from the end face of the ring body. Its position corresponds to the first side opening in the radial direction. A partition wall is also retained between the second observation window and the expansion block groove to prevent the reset spring strip from coming out of the second observation window. The two ends of the reset spring strip enter the expansion block groove from the openings of the first side opening and the second side opening, respectively, until they stop at the inner surfaces of the first observation window and the second observation window. That is, the two ends of the reset spring strip are exactly at the corresponding positions of the first observation window and the second observation window, which makes it easy to directly observe the state of the spring ends through the observation window.

[0012] Furthermore, the outer periphery of both cross-sections of the ring body is chamfered.

[0013] Furthermore, an embedding channel is provided between the semi-circular bottom and the top of the expansion block. The embedding channel is a groove-shaped structure formed by indentation from the side of the expansion block, and its extension direction is parallel to the swing axis of the expansion block. It is used for embedding the reset spring strip to achieve stable contact and force transmission between the reset spring strip and the expansion block.

[0014] Furthermore, the embedded channel is a unidirectional channel, that is, one end of the embedded channel is an open end and the other end is a closed end; the open end faces the side of the expansion block and is used to allow the reset spring strip to be inserted from the side; the closed end is located inside the expansion block and is used to limit the insertion depth of the reset spring strip to prevent the spring strip from being inserted too much and affecting the normal swing of the expansion block. The embedded channel is provided with a spring strip groove near the closed end. The spring strip groove is a pit or groove structure formed by the bottom surface of the embedded channel being recessed downwards, and its bottom surface is lower than the bottom surface of the embedded channel. The spring bar groove is used to accommodate and position the end of the reset spring bar. When the reset spring bar is inserted into the embedding channel and pushed to the deepest point, the middle section of the reset spring bar enters the spring bar groove, forming an embedded limiting fit. This prevents the reset spring bar from coming out of the embedding channel due to vibration or expansion block swing during use, ensuring that the relative position between the reset spring bar and the expansion block remains stable over a long period of time.

[0015] Furthermore, locking plates are provided at both ends of the felt strip on the side away from the interlocking strip, and bolts pass through the locking plates, the felt strip, the interlocking strip, and finally connect to the shaft core.

[0016] Furthermore, a partition is provided between every two mechanical expanders, and a positioning inner protrusion is provided on the inner side of the partition. The shaft core is provided with a positioning groove, and the positioning inner protrusion is inserted into the positioning groove. Several mechanical expanders and diaphragms have end sleeves at both ends.

[0017] Furthermore, the two ends of the expansion block are provided with expansion block chamfers, which are inclined surfaces or arc surfaces machined from the edge of the end face of the expansion block inward, in order to eliminate the sharp edges at both ends of the expansion block.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. By introducing pressurized gas into the vent, the felt strip rapidly expands radially outward under the pressure, forming a tight contact with the inner wall of the mechanical expander, achieving instant locking; after releasing the pressure, the felt strip automatically contracts under its own elastic restoring force, and the mechanical expander returns to a free rotation state. This process requires no manual intervention, has a fast response speed, facilitates automated control and rapid roll changing, and greatly improves production efficiency.

[0019] 2. A reset spring is installed. After the external driving force is removed, the reset spring automatically pushes the expansion block back to the extended position, realizing automatic reset of the tensioning lock. This completely solves the problem that traditional tensioning structures cannot reset on their own and require manual pressing or prying, reducing manual operation time and eliminating production bottlenecks caused by manual intervention. In use, multiple tensioning structures are sleeved on the outside of the tensioning shaft. By inserting and rotating the external components, the interference between the inner wall of the external components and the top head is used to make the top head temporarily retract under the pressure. After insertion, rotating in the opposite direction will automatically tighten and lock the structure. To disassemble, simply rotate the external components in the opposite direction to retract the top head and pull it out. This operation method is simple and intuitive, requires no special tools, and significantly improves the efficiency of core replacement and component loading and unloading. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and, together with the embodiments thereof, are used to explain the invention. They do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall expansion structure according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the expansion structure according to an embodiment of the present invention; Figure 3 This is an exploded schematic diagram of the expansion structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the shaft core structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the explosion of the expansion bar according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the mechanical expander and diaphragm structure according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the mechanical expander structure according to an embodiment of the present invention; Figure 8 This is a front view of the mechanical expander according to an embodiment of the present invention; Figure 9 This is a perspective view of the mechanical expander according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the explosion of the mechanical expander according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the expansion block structure according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the ring structure according to an embodiment of the present invention.

[0021] In the diagram: 1. Shaft core; 101. Vent hole; 102. Fitting groove; 1021. Air outlet hole; 2. Expansion strip; 201. Fitting strip; 2011. Air supply hole; 202. Felt strip; 203. Locking plate; 204. Bolt; 3. End sleeve; 41. Ring body; 4101. Expansion block groove; 4102. First side opening; 4103. Second side opening; 41031. Rotating receiving cavity; 4104. Chamfer; 4105. First observation window; 4106. Second observation window; 42. Expansion block; 421. Semi-circular bottom; 4201. Spring strip groove; 4202. Embedded channel; 4203. Expansion block chamfer; 422. Top head; 43. Return spring strip. Detailed Implementation

[0022] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the invention.

[0023] like Figures 1 to 12As shown, a combined expansion and tightening device for fixing a shaft includes a shaft core 1, which is the central load-bearing component of the entire expansion and tightening structure, used to bear the torque and radial load transmitted by external components. A vent 101 is provided at the center of the shaft core 1, extending axially along the shaft core 1 as a channel for supplying pressurized gas. One end of the vent 101 is connected to an external air source such as an air compressor or pneumatic control system, while the other end is closed. The design of the vent 101 allows for centralized air pressure control, facilitating automated control.

[0024] A fitting groove 102 is provided around the periphery of the shaft core 1, which is recessed towards the inside of the shaft core 1. The fitting groove 102 extends along the axial direction of the shaft core 1 and is used to accommodate and position the expansion strip 2.

[0025] The fitting groove 102 is detachably connected to the expansion bar 2. This detachable design allows the expansion bar 2 to be easily replaced when it ages or is damaged due to long-term use, without having to replace the entire shaft core 1, which greatly reduces maintenance costs. The bottom of the fitting groove 102 is provided with an air outlet 1021, which is connected to the vent hole 101.

[0026] The expansion strip 2 includes a fitting strip 201 and a felt strip 202. The fitting strip 201 is a rigid strip-shaped component, typically made of aluminum alloy, engineering plastic, or stainless steel. Its shape matches the fitting groove 102, and it is used to fix the expansion strip 2 to the shaft core 1 and provide a rigid support base for the felt strip 202. The fitting strip 201 is provided with an air inlet 2011 corresponding to the air outlet 1021. The air inlet 2011 extends through the thickness direction of the fitting strip 201, and its position is precisely aligned with the air outlet 1021 to ensure that gas can flow smoothly from the air outlet 1021 into the air inlet 2011 and then be evenly distributed to the back of the felt strip 202.

[0027] Felt strip 202 is disposed on the outside of interlocking strip 201. Felt strip 202 is made of high-density wool felt and has natural air permeability channels. When pressurized gas enters felt strip 202 through air inlet 2011, the gas can rapidly diffuse in the fiber gaps of felt strip 202, achieving uniform pressure distribution across the entire contact surface. This allows felt strip 202 to expand radially outward evenly and smoothly during inflation, without local bulging or uneven expansion. This uniform expansion characteristic ensures that the contact pressure between felt strip 202 and the inner wall of mechanical expander 4 is uniformly distributed axially and circumferentially, forming a stable and reliable locking force.

[0028] The felt strip 202 is soft in texture and forms a flexible surface contact when it expands and abuts against the inner wall of the mechanical expander 4. This flexible contact method is completely different from the rigid locking of traditional metal-to-metal connections, such as key connections and screw locking. It will not cause scratches, indentations or wear to the inner wall of the mechanical expander 4, and is particularly suitable for occasions that require frequent disassembly and assembly or have high requirements for the precision of the mating surfaces. Therefore, it extends the service life of the mechanical expander 4 and the shaft core 1.

[0029] Felt material has a high coefficient of friction, especially under pressure. The static friction coefficient between the felt strip 202 and the metal surface can reach 0.4 to 0.7, which is much higher than the friction coefficient between metals. When the felt strip 202 expands and presses against the inner wall of the mechanical expander 4, the resulting friction can effectively resist the torque load on the mechanical expander 4 during rotation, preventing it from slipping or rotating relative to the shaft core 1, and ensuring a stable and reliable locking state.

[0030] The felt strip 202 has excellent elastic recovery capability. When the vent 101 is depressurized, the air pressure inside the felt strip 202 drops rapidly. Under the action of its own elastic recovery force, the felt strip 202 can quickly and evenly shrink back to its original size and shape, completely releasing its contact with the inner wall of the mechanical expander 4. This automatic reset feature eliminates the need for an additional reset mechanism, resulting in a simple structure and fast response speed, facilitating rapid roll changing and automated control.

[0031] The fibrous structure of the felt strip 202 possesses a certain degree of abrasion resistance. During repeated inflation and deflation, the felt strip 402 maintains its structural integrity and is not prone to permanent deformation or fatigue damage. Even after tens of thousands of working cycles, it maintains stable expansion performance and locking effect. When the performance of the felt strip 202 deteriorates due to long-term use, due to its detachable connection structure with the interlocking strip 201, a new felt strip 202 can be quickly replaced simply by pulling the expansion strip 2 out of the interlocking groove 102, resulting in low maintenance costs.

[0032] The flexible fiber structure of the felt strip 202 has excellent vibration absorption and noise reduction properties. When the expansion structure rotates at high speed, the felt strip 202 can absorb mechanical vibration and reduce impact noise caused by the tiny gap between the shaft core 1 and the mechanical expander 4, making the equipment operate more quietly and smoothly and improving the working environment.

[0033] When pressurized gas is introduced into the vent 101, the gas flows sequentially through the vent 101, the outlet 1021, and the inlet 2011, finally reaching the felt strip 202. This causes the felt strip 202 to expand radially outward under pressure, increasing its volume and thus forming a tight contact with the inner wall of the mechanical expander 4, which is sleeved on the outside of the shaft core 1. This generates friction or mechanical locking force, locking the mechanical expander 4 and preventing it from rotating relative to the shaft core 1. When unlocking is required, simply release the air pressure. The felt strip 202 automatically contracts under its own elastic restoring force, allowing the mechanical expander 4 to resume free rotation. This achieves rapid and automated control of locking and unlocking between the mechanical expander 4 and the shaft core 1.

[0034] Locking plates 203 are provided at both ends of the felt strip 202 on the side away from the interlocking strip 201. The locking plates 203 are rigid flat components made of stainless steel, carbon steel, or high-strength engineering plastics, and have sufficient structural strength and bending stiffness. The locking plates 203 apply uniform clamping force from the outer side of the ends of the felt strip 202 to prevent the felt strip 202 from bulging outward from the ends or undergoing axial displacement due to internal air pressure during inflation, ensuring that the felt strip 202 expands only in the radial direction. The locking plates 203 and the ends of the felt strip 202 form an end-face sealing structure, effectively reducing the path of pressurized gas leakage from both ends of the felt strip 202, improving gas utilization efficiency and the reliability of expansion and locking. When the felt strip 202 is depressurized and contracted, the locking plates 203 play an auxiliary role in returning to their original position, preventing the ends of the felt strip 202 from undergoing permanent deformation or warping due to repeated expansion and contraction.

[0035] Bolt 204 passes through locking plate 203, felt strip 202, and fitting strip 201, and finally connects to shaft core 1 by thread. Locking plate 203, felt strip 202 and fitting strip 201 are pressed and fixed to shaft core 1 in sequence. This detachable bolt connection structure makes it easy and quick to maintain the shaft core 1. When felt strip 202 needs to be replaced due to aging or damage from long-term use, simply unscrew bolt 204 to remove locking plate 203, pull out old expansion strip 2 and install new expansion strip 2. The maintenance operation is simple and quick, without the need to replace the entire shaft core 1, which greatly reduces maintenance costs.

[0036] The mechanical expander 4 includes a ring body 41, which is a ring structure and is used to be sleeved on the outside of the shaft or as part of the shaft. Its outer circumferential surface is used to form a fit with the inner wall of the external component. A number of expansion blocks 42 are movably connected to the ring body 41. The expansion blocks 42 are evenly distributed along the circumference of the ring body 41 and are used to extend outward or retract inward in the radial direction to achieve tightening and locking or unlocking with external components. The ring body 41 has several expansion block slots 4101, each slot 4101 corresponding to an expansion block 42; the circumferential angle between adjacent expansion blocks 42 is equal. This uniform distribution design ensures the symmetry and uniformity of the tensioning force in the circumferential direction, avoiding tensioning failure or deformation of external components due to eccentric loading. The expansion blocks 42 are used to extend outward or retract inward in the radial direction to achieve tensioning locking or unlocking with external components.

[0037] The bottom of the expansion block groove 4101 is semi-circular, which is used to form a rotational engagement with the semi-circular bottom 421 of the expansion block 42, so that the expansion block 42 can swing around the center of the semi-circular bottom 421 in the expansion block groove 4101. Compared with the traditional planar sliding or hinge connection, this semi-circular surface contact design has the advantages of low contact stress, low wear, and flexible rotation, so that the expansion block 42 can swing smoothly around the center of the semi-circular bottom 421 in the expansion block groove 4101.

[0038] The other end of the expansion block 42 is provided with a top head 422, which is the free end of the expansion block 42. It is used to protrude from the circumferential surface of the ring body 41 when the expansion block 42 swings outward, and abut against the inner wall of the external component to achieve expansion and locking. The first opening of the expansion block groove 4101 is located on the circumferential wall of the ring body 41, so that the expansion block groove 4101 communicates with the outside of the ring body 41. When the expansion block 42 rotates in the first direction, the top head 422 is hidden inside the coil body 41. At this time, the tensioning structure is in a contracted state, and there is no contact or only slight contact between the expansion block 42 and the external components. The external components can be freely installed and removed. This state is suitable for scenarios where the core needs to be replaced or the external components need to be disassembled.

[0039] When the expansion block 42 rotates in the second direction, the top head 422 protrudes beyond the circumference of the ring body 41. At this time, the expansion block 42 abuts against the inner wall of the external component, generating radial tension force and achieving tension locking. In the locked state, a keyless connection is formed between the ring body 41 and the external component, which can transmit a large torque without relative slippage.

[0040] A return spring strip 43 is embedded inside the ring body 41. In its natural state, the elastic force of the return spring strip 43 forces the expansion block 42 to maintain an outward extension tendency, causing the top head 422 to protrude from the circumferential surface of the ring body 41, thereby automatically achieving a tightened and locked state. When it is necessary to unlock, an external driving force overcomes the elastic force of the return spring strip 43, forcing the expansion block 42 to rotate in the first direction, causing the top head 422 to retract into the ring body 41; when the external driving force is released, the elastic force of the return spring strip 43 again drives the expansion block 42 to rotate in the second direction, automatically restoring the tightened and locked state.

[0041] In use, multiple tensioning structures are fitted onto the outside of the tensioning shaft, allowing the tensioning structures to tighten and fix the cylinder to be processed. When the equipment is not running or the tensioning structures are not driven, the elastic force of the return spring strip 43 continuously acts on the expansion block 42, forcing the expansion block 42 to rotate around the center of the semi-circular bottom 421 in the second direction. The top head 422 protrudes from the circumferential surface of the ring body 41 and is in a state of waiting to be tightened. At this time, the outer diameter of the tensioning structure is larger than the inner diameter of the external component, but the tensioning structure has not yet been inserted into the external component.

[0042] The ring body 41, along with the protruding expansion block 42, is inserted into the inner hole of the outer component. During insertion, because the top head 422 protrudes from the circumferential surface of the ring body 41, interference occurs between the top head 422 and the inner wall of the outer component. Therefore, the outer component is rotated while being inserted, causing its inner wall to drive the top head 422 to rotate in the first direction. Under the squeezing force of the inner wall of the outer component, the top head 422 is forced to swing inward, compressing the return spring bar 43 and temporarily retracting the top head 422, allowing the ring body 41 to be inserted smoothly. After insertion, the outer component is rotated in the second direction, causing the elastic force of the return spring bar 43 to once again cause the top head 422 to pop outward, pressing against the inner wall of the outer component to achieve expansion and locking.

[0043] When it is necessary to remove the outer component from the ring 41, simply rotate the outer component again in the first direction to retract the top 422 into the ring 41. At this time, the outer diameter of the tensioning structure is less than or equal to the inner diameter of the outer component, and the outer component can be pulled out from the tensioning structure during the gradual rotation process.

[0044] After the external driving force is removed, the reset spring bar 43 automatically pushes the expansion block 42 back to the extended position, realizing the automatic reset of the tension lock. This solves the problem that the traditional tension structure cannot reset itself and requires manual pressing or prying, greatly improving the automation level of the equipment.

[0045] The reset spring strip 43 is fitted inside the ring body 41, and the expansion block 42 is directly connected to the expansion block groove 4101 through the semi-circular bottom 421. No additional rotating shaft, hinge or external reset mechanism is required. The overall structure is compact and saves installation space.

[0046] The expansion block 42 adopts a semi-circular arc surface to form a rotational fit with the bottom of the expansion block groove 4101. Compared with traditional sliding friction or wedge friction, the contact stress is small and the wear is low, which extends the service life of the expansion block 42 and the ring body 41.

[0047] Multiple expansion blocks 42 are evenly distributed around the circumference of the ring body 41. The force exerted by the reset spring strip 43 on each expansion block 42 is consistent, ensuring the uniformity of the force on the circumference during tightening and locking, avoiding uneven load and local stress concentration, and improving the reliability of tightening.

[0048] By adjusting parameters such as the elasticity of the reset spring bar 43, the number and size of the expansion blocks 42, and the protrusion height of the top head 422, it can adapt to application scenarios with different diameters and different tension requirements, and is suitable for winding equipment and transmission devices in industries such as printing, packaging, textiles, papermaking, and plastic film.

[0049] The second opening of the expansion block groove 4101 communicates with one side of the ring body 41; this side is the axial end face of the ring body 41. The design of the second opening connects the expansion block groove 4101 with the outside of the end face of the ring body 41, providing an operating channel for the expansion block 42 to enter the expansion block groove 4101 from the axial end face of the ring body 41. This axial opening design does not affect the integrity of the outer circumferential surface of the ring body 41, ensuring the continuity and strength of the tightening structure in the circumferential direction.

[0050] The expansion block groove 4101 has a first side opening 4102 and a second side opening 4103 on both sides. The first side opening 4102 and the second side opening 4103 are both clearance spaces extending outward from the side wall of the expansion block groove 4101, and their opening direction is consistent with the direction of the second opening. They are used to provide clearance space for the expansion block 42 during rotation and prevent the expansion block 42 from interfering with the ring body 41. A rotation receiving cavity 41031 is provided near the circumference of the ring body 41 in the second side opening 4103. The rotation receiving cavity 41031 is an arc-shaped or hemispherical cavity formed by inward indentation from the second side opening 4103. When the expansion block 42 rotates in the first direction under the action of external driving force, the top head 422 swings towards the first side opening 4102; at the same time, the semi-circular bottom 421 swings towards the second side opening 4103. The upper end of the semi-circular bottom 421 gradually fits into the rotating receiving cavity 41031, so that the expansion block 42 can obtain a larger rotation angle, thereby realizing that the top head 422 is completely retracted into the ring body 41, releasing the expansion and locking state. The arc surface of the rotating receiving cavity 41031 and the semi-circular bottom 421 form a stable rotation fulcrum, ensuring the stability of the expansion block 42 in the retracted position and avoiding poor reset due to shaking. The rotating receiving cavity 41031 plays a limiting role when the expansion block 42 extends, preventing the expansion block 42 from falling out of the groove due to excessive swing of the semi-circular bottom 421.

[0051] A first observation window 4105 is provided on the side of the ring body 41 away from the second side opening 4103. The first observation window 4105 is a through window structure formed by recessing inward from the end face of the ring body 41, and its position corresponds to the second side opening 4103 in the radial direction. A partition wall is maintained between the first observation window 4105 and the expansion block groove 4101 to prevent the reset spring bar 43 from coming out of the first observation window 4105. A second observation window 4106 is provided on the side of the ring body 41 away from the first side opening 4102. The second observation window 4106 is a through window structure formed by an inward recess from the end face of the ring body 41, and its position corresponds to the first side opening 4102 in the radial direction. A partition wall is also maintained between the second observation window 4106 and the expansion block groove 4101 to prevent the reset spring strip 43 from coming out of the second observation window 4106. The two ends of the reset spring bar 43 enter the expansion block groove 4101 from the openings of the first side opening 4102 and the second side opening 4103 respectively, until they stop at the inner surfaces of the first observation window 4105 and the second observation window 4106. That is, the two ends of the reset spring bar 43 are exactly located at the corresponding positions of the first observation window 4105 and the second observation window 4106, which makes it easy to directly observe the state of the spring ends through the observation windows.

[0052] During assembly, operators can directly observe whether both ends of the reset spring strip 43 have reached the preset position through the first observation window 4105 and the second observation window 4106. This visual assembly verification method avoids rework or assembly defects caused by the inability to confirm the spring strip's position in the traditional blind assembly method, significantly improving assembly efficiency and first-pass yield. Especially in multi-expansion block structures, the installation status of each spring strip or each segment of the spring strip can be confirmed one by one through the observation windows, ensuring the consistency of assembly quality.

[0053] When it is necessary to replace the reset spring bar 43, the position of the end of the spring bar can be accurately confirmed through the observation window, which makes it convenient for the operator to insert a tool from the first side opening 4102 or the second side opening 4103 to push or pull the spring bar.

[0054] The partition wall between the first observation window 4105, the second observation window 4106, and the expansion block groove 4101 is a critical safety design feature. Even if the reset spring bar 43 breaks or its end warps in extreme circumstances, the partition wall effectively prevents the spring bar from detaching from the observation window, avoiding secondary damage or safety accidents caused by the spring bar falling into the equipment. This dual protection design significantly improves the safety of the expansion structure.

[0055] Both outer peripheries of the ring body 41 have chamfers 4104. The chamfers 4104 are inclined or arc-shaped surfaces machined inwards from the edge of the ring body 41's end face. These chamfers eliminate sharp edges on the outer periphery of the ring body 41's end face, facilitating smooth installation and removal of the ring body 41 from the shaft. They also prevent scratching of operators' hands or damage to the surfaces of mating components during installation, use, or maintenance. When the ring body 41 is subjected to axial impact loads, radial expansion reaction forces, or alternating stress, the sharp edges may become initiation points for fatigue cracks, leading to cracking or even breakage of the ring body 41 during use. This risk is particularly pronounced under high-speed rotation or frequent expansion and contraction conditions. The chamfers 4104 eliminate this stress concentration area, resulting in a more uniform stress distribution, improving the fatigue strength and impact resistance of the ring body 41, and extending the service life of the expansion structure.

[0056] An embedding channel 4202 is provided between the semi-circular bottom 421 and the top 422 of the expansion block 42. The embedding channel 4202 is a groove-shaped structure formed by indentation from the side of the expansion block 42, and its extension direction is parallel to the swing axis of the expansion block 42. It is used for embedding the return spring strip 43 to achieve stable contact and force transmission between the return spring strip 43 and the expansion block 42. The embedding channel 4202 is located in the lower middle part of the expansion block 42, so that the elastic force of the return spring strip 43 can act on the rotation center of the expansion block 42 with the most reasonable lever arm, thereby obtaining a large return torque with a small spring force and improving the utilization efficiency of the spring force. The cross-sectional shape of the embedding channel 4202 matches the cross-sectional shape of the return spring strip 43. When the return spring strip 43 is embedded in the embedding channel 4202, the expansion block 42 forms a three-sided surrounding structure for the spring strip, effectively preventing the return spring strip 43 from lateral slippage or dislodgement during the swing of the expansion block 42, and ensuring that the direction of the spring force is always consistent with the design direction.

[0057] The embedding channel 4202 is a unidirectional channel, meaning one end of the embedding channel 4202 is open and the other end is closed. The open end faces the side of the expansion block 42, allowing the return spring strip 43 to be inserted from the side. The closed end is located inside the expansion block 42, limiting the insertion depth of the return spring strip 43 and preventing excessive insertion that could affect the normal swing of the expansion block 42. Operators only need to push the return spring strip 43 from the open end until it touches the closed end to confirm it is in place, eliminating the need for measuring tools or experience-based judgment. This significantly reduces assembly difficulty and the skill requirements for operators, ensuring consistent assembly quality.

[0058] A spring strip groove 4201 is provided near the closed end of the embedded channel 4202. The spring strip groove 4201 is a pit or groove structure formed by the bottom surface of the embedded channel 4202 being recessed downwards, and its bottom surface is lower than the bottom surface of the embedded channel 4202. The spring strip groove 4201 is used to accommodate and position the end of the reset spring strip 43. When the reset spring strip 43 is inserted into the embedded channel 4202 and pushed to the deepest point, the middle section of the reset spring strip 43 enters the spring strip groove 4201, forming an embedded limiting fit, preventing the reset spring strip 43 from being removed from the embedded channel 4202 due to vibration or the swing of the expansion block 42 during use, and ensuring that the relative position between the reset spring strip 43 and the expansion block 42 remains stable for a long time. When the end of the spring bar is inserted into the groove, because the depth of the groove is lower than the bottom surface of the insertion channel 4202, the spring bar needs to overcome a certain potential energy to be released from the groove. This mechanical interlocking structure effectively prevents the reset spring bar 43 from gradually exiting the insertion channel 4202 due to vibration, impact, or reciprocating swing of the expansion block 42 during use. Even if the reset spring bar 43 experiences slight stress relaxation or length changes after long-term use, the end is still constrained within the groove range and will not completely come out, ensuring the basic existence of the reset force. The positioning effect of the groove keeps the relative position of the reset spring bar 43 and the expansion block 42 stable for a long time, ensuring the consistency of the spring bar's force application point and direction during each reset action, thereby improving the repeatability and reliability of the reset action.

[0059] The depth of the spring bar groove 4201 is 0.2 to 0.5 times the diameter of the return spring bar 43, and the width matches the diameter of the return spring bar 43. This is used to accommodate the end of the return spring bar 43 while still maintaining a certain axial movement margin, so as to avoid additional stress on the return spring bar 43 due to excessive constraint.

[0060] The expansion block 42 has chamfers 4203 at both ends. The chamfers 4203 are inclined or arc-shaped surfaces machined from the edge of the end face of the expansion block 42 inward, used to eliminate the sharp edges at both ends of the expansion block 42. When the expansion block 42 reciprocates within the expansion block groove 4101, the end faces may come into contact with the sidewall of the groove. Without the chamfers 4203, the sharp edges of the end faces would generate significant frictional resistance upon contact, and may even cause scraping or jamming, affecting the flexible swinging and reset response speed of the expansion block 42.

[0061] The return spring bar 43 is made of spring steel. The high elastic limit of spring steel ensures that it can still provide sufficient return force after long-term use and will not loosen due to plastic deformation. The excellent fatigue strength of spring steel ensures that it can withstand more than one million cycles of load without breaking, and has extremely high reliability.

[0062] A spacer 5 is provided between every two mechanical expanders 4. The spacer 5 is an annular thin sheet component. The spacer 5 is used to separate adjacent mechanical expanders 4, preventing them from moving or colliding with each other in the axial direction. At the same time, it provides an independent axial positioning reference for each mechanical expander 4, ensuring that each mechanical expander 4 maintains a uniform axial spacing on the shaft core 1. The spacer 5 also facilitates heat dissipation, preventing the mechanical expanders 4 from overheating due to frictional heat generation when rotating at high speed.

[0063] The inner side of the partition 5 is provided with a positioning inner protrusion 501, which is a block-shaped or ring-shaped structure that protrudes radially inward from the inner edge of the partition 5. The positioning inner protrusion 501 is used to cooperate with the positioning structure on the shaft core 1 to realize the circumferential positioning and anti-rotation function of the partition 5 on the shaft core 1.

[0064] The shaft core 1 is provided with a positioning groove, which is a groove-shaped structure formed by recessing from the outer circumference of the shaft core 1 inward. The positioning groove extends along the axial direction of the shaft core 1 and corresponds to the positioning inner protrusion 501. The positioning inner protrusion 501 is inserted into the positioning groove to form a keyway or spline connection. This connection method can prevent the spacer 5 from circumferentially sliding relative to the shaft core 1 when the shaft core 1 rotates, ensuring that the spacer 5 and the shaft core 1 rotate synchronously; and it provides a circumferential positioning reference for the spacer 5, which facilitates the quick determination of the installation angle of the spacer 5 during assembly; thus, a reliable torque transmission path is formed between the spacer 5 and the shaft core 1, so that the torque of the shaft core 1 can be transmitted to the mechanical expander 4 through the spacer 5.

[0065] Several mechanical expanders 4 and spacers 5 are provided with end sleeves 3 at both ends. The end sleeves 3 are annular sleeve-shaped components that are sleeved on both ends of the shaft core 1. The end sleeves 3 are used to axially limit and press the assembled mechanical expanders 4 and spacers 5 to prevent the components from axially moving or separating on the shaft core 1, and to ensure the dimensional stability and structural integrity of the entire expansion structure in the axial direction.

[0066] The end sleeve 3 axially presses together multiple mechanical expanders 4 and spacers 5, eliminating axial gaps between components and forming a rigid whole, reducing vibration and noise during operation; it provides end protection for the entire expansion structure, preventing dust, debris and other impurities from entering the gap between the mechanical expander 4 and the shaft core 1; when disassembly and maintenance are required, simply remove the end sleeve 3, and the mechanical expander 4 and spacers 5 can be slid out from the shaft core 1 in sequence, facilitating inspection and replacement.

[0067] The combination structure of the spacer 5 and the end sleeve 3 allows multiple mechanical expanders 4 to be set on a single shaft core 1 at the same time. Each mechanical expander 4 can be independently controlled to tighten and loosen. It is suitable for complex application scenarios that require segmented tightening of cores of different widths on the same shaft, such as multi-segment winding and unwinding shafts, slitting machine winding shafts, etc., which greatly expands the application range and flexibility of the tightening structure.

[0068] The expansion structure of the present invention introduces pressurized gas into the vent 101. Under the action of air pressure, the felt strip 202 rapidly expands radially outward and forms a tight contact with the inner wall of the mechanical expander 4, achieving instant locking. After the air pressure is released, the felt strip 202 automatically contracts under its own elastic restoring force, and the mechanical expander 4 returns to a free rotation state. This process does not require manual intervention, has a fast response speed, facilitates automated control and rapid roll changing, and greatly improves production efficiency.

[0069] A reset spring bar 43 is provided. After the external driving force is removed, the reset spring bar 43 automatically pushes the expansion block 42 back to the extended position, realizing the automatic reset of the tension lock. This completely solves the problem that traditional tensioning structures cannot reset on their own and require manual pressing or prying. It reduces the time of manual operation and eliminates the production bottleneck caused by manual intervention. In use, multiple tensioning structures are sleeved on the outside of the tensioning shaft. By inserting and rotating the external components at the same time, the interference cooperation between the inner wall of the external components and the top head 422 is used to make the top head 422 temporarily retract under the pressure. After insertion, rotating in the opposite direction will automatically tighten and lock the structure. When disassembling, simply rotate the external components in the opposite direction to make the top head 422 retract and pull it out. This operation method is simple and intuitive, requires no special tools, and significantly improves the efficiency of core replacement and component loading and unloading.

[0070] The reset spring strip 43 is fitted inside the coil body 41, and the expansion block 42 is directly rotatably connected to the expansion block groove 4101 through the semi-circular bottom 421, eliminating the need for additional rotating shafts, hinges, or external reset mechanisms. The overall structure is compact with few parts, saving installation space and making it particularly suitable for space-constrained equipment installation environments, which is beneficial for the miniaturization and lightweight design of equipment.

[0071] The expansion block 42 adopts a semi-circular arc surface to form a rotational fit with the bottom of the expansion block groove 4101. Compared with traditional sliding friction or wedge friction, it has low contact stress, low frictional resistance, and low wear, which extends the service life of the expansion block 42 and the ring body 41 and reduces the total life cycle maintenance cost.

[0072] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A combined expansion clamping device for fixing a shaft, characterized in that, Includes a shaft core (1), with a vent hole (101) at the center of the shaft core (1) and a fitting groove (102) recessed towards the inside of the shaft core (1) around the periphery of the shaft core (1). The fitting groove (102) is detachably connected to an expansion strip (2), and the fitting groove (102) is provided with an air outlet (1021); the expansion strip (2) includes a fitting strip (201) and a felt strip (202); the fitting strip (201) is provided with an air supply hole (2011) corresponding to the air outlet (1021); when pressurized gas is introduced into the vent (101), the gas flows through the vent (101), the air outlet (1021), and the air supply hole (2011) in sequence, and finally reaches the felt strip (202), causing the felt strip (202) to expand radially outward under the action of air pressure and increase its volume, thereby forming a tight contact with the inner wall of the mechanical expander (4) sleeved on the outside of the shaft core (1), generating friction or mechanical locking force, so that the mechanical expander (4) is locked and cannot rotate relative to the shaft core (1); The mechanical expander (4) includes a ring body (41), which is an annular structure. Several expansion blocks (42) are movably connected on the ring body (41). The expansion blocks (42) are evenly distributed along the circumference of the ring body (41) and are used to extend outward or retract inward in the radial direction to achieve expansion locking or unlocking with external components.

2. The combined expansion and tightening device for fixing a shaft according to claim 1, characterized in that, The ring body (41) is provided with a number of expansion block slots (4101), each expansion block slot (4101) corresponding to accommodate an expansion block (42); the bottom of the expansion block slot (4101) is semi-circular arc-shaped, which is used to form a rotational fit with the semi-circular arc bottom (421) of the expansion block (42), so that the expansion block (42) can swing around the center of the semi-circular arc bottom (421) in the expansion block slot (4101); The other end of the expansion block (42) is provided with a top head (422), which is the free end of the expansion block (42) and is used to protrude from the circumferential surface of the ring body (41) when the expansion block (42) swings outward, and abut against the inner wall of the external component to achieve expansion and locking. The first opening of the expansion block groove (4101) is located on the circumferential wall of the ring body (41), so that the expansion block groove (4101) communicates with the outside of the ring body (41); When the expansion block (42) rotates in the first direction, the top head (422) is hidden inside the ring body (41). At this time, the expansion and tightening structure is in a contracted state, and the external components can be freely installed and removed. When the expansion block (42) rotates in the second direction, the top head (422) protrudes beyond the circumference of the ring body (41). At this time, the expansion block (42) abuts against the inner wall of the external component to achieve expansion and locking. The ring (41) is fitted with a reset spring strip (43), which has a spring force that drives the expansion block (42) to rotate in the second direction.

3. The combined expansion and tightening device for fixing a shaft according to claim 2, characterized in that, The second opening of the expansion block groove (4101) communicates with one side of the ring body (41); this side is the axial end face of the ring body (41); The expansion block groove (4101) is provided with a first side opening (4102) and a second side opening (4103) on both sides respectively; the first side opening (4102) and the second side opening (4103) are both clearance spaces extending outward from the side wall of the expansion block groove (4101), and their opening direction is consistent with the direction of the second opening, which are used to provide clearance space for the expansion block (42) during rotation and prevent the expansion block (42) from interfering with the ring body (41); The second side opening (4103) is provided with a rotating receiving cavity (41031) near the circumference of the ring body (41). The rotating receiving cavity (41031) is an arc-shaped or hemispherical cavity formed by indentation from the second side opening (4103). When the expansion block (42) rotates in the first direction under the action of external driving force, the top head (422) swings towards the first side opening (4102); at the same time, the semi-circular bottom (421) swings towards the second side opening (4103), and the upper end of the semi-circular bottom (421) gradually fits into the rotating receiving cavity (41031), so that the expansion block (42) can obtain a larger rotation angle, thereby realizing that the top head (422) is completely retracted into the ring body (41) and the expansion locking state is released.

4. The combined expansion and tightening device for fixing a shaft according to claim 3, characterized in that, A first observation window (4105) is provided on the side of the ring body (41) away from the second side opening (4103). The first observation window (4105) is a through window structure formed by recessing inward from the end face of the ring body (41). Its position corresponds to the second side opening (4103) in the radial direction. A partition wall is maintained between the first observation window (4105) and the expansion block groove (4101) to prevent the reset spring strip (43) from coming out of the first observation window (4105). A second observation window (4106) is provided on the side of the ring body (41) away from the first side opening (4102). The second observation window (4106) is a through window structure formed by recessing inward from the end face of the ring body (41). Its position corresponds to the first side opening (4102) in the radial direction. A partition wall is also maintained between the second observation window (4106) and the expansion block groove (4101) to prevent the reset spring strip (43) from coming out of the second observation window (4106). The two ends of the reset spring bar (43) enter the expansion block groove (4101) from the openings of the first side opening (4102) and the second side opening (4103) respectively, until they stop at the inner side of the first observation window (4105) and the second observation window (4106). That is, the two ends of the reset spring bar (43) are exactly located at the corresponding positions of the first observation window (4105) and the second observation window (4106), which makes it easy to directly observe the state of the spring ends through the observation windows.

5. A combined expansion clamping device for fixing a shaft according to claim 4, characterized in that, The outer periphery of both sections of the ring body (41) is provided with chamfers (4104).

6. A combined expansion clamping device for fixing a shaft according to any one of claims 2 to 5, characterized in that, An embedding channel (4202) is provided between the semi-circular bottom (421) and the top (422) of the expansion block (42). The embedding channel (4202) is a groove-shaped structure formed by indentation from the side of the expansion block (42). Its extension direction is parallel to the swing axis of the expansion block (42). It is used for embedding the reset spring strip (43) to achieve stable contact and force transmission between the reset spring strip (43) and the expansion block (42).

7. A combined expansion clamping device for fixing a shaft according to claim 6, characterized in that, The embedded channel (4202) is a one-way channel, that is, one end of the embedded channel (4202) is an open end and the other end is a closed end; the open end faces the side of the expansion block (42) and is used to allow the reset spring strip (43) to be inserted from the side; the closed end is located inside the expansion block (42) and is used to limit the insertion depth of the reset spring strip (43) to prevent the spring strip from being inserted too much and affecting the normal swing of the expansion block (42); The embedded channel (4202) is provided with a spring strip groove (4201) near the closed end. The spring strip groove (4201) is a pit or groove structure formed by the bottom surface of the embedded channel (4202) being recessed downwards, and its bottom surface is lower than the bottom surface of the embedded channel (4202). The spring bar groove (4201) is used to accommodate and position the end of the reset spring bar (43). When the reset spring bar (43) is inserted into the embedding channel (4202) and pushed to the deepest point, the middle section of the reset spring bar (43) is inserted into the spring bar groove (4201) to form an embedded limiting fit, preventing the reset spring bar (43) from being pulled out of the embedding channel (4202) due to vibration or the swing of the expansion block (42) during use, and ensuring that the relative position between the reset spring bar (43) and the expansion block (42) remains stable for a long time.

8. A combined expansion clamping device for fixing a shaft according to any one of claims 2 to 5, characterized in that, Locking plates (203) are provided on the side away from the mating strip (201) at both ends of the felt strip (202). Bolts (204) pass through the locking plate (203), the felt strip (202), the mating strip (201), and finally connect to the shaft core (1).

9. A combined expansion clamping device for fixing a shaft according to any one of claims 1 to 4, characterized in that, A partition (5) is provided between each pair of mechanical expanders (4), and a positioning inner protrusion (501) is provided on the inner side of the partition (5). The shaft core (1) is provided with a positioning groove, and the positioning inner protrusion (501) is inserted into the positioning groove. Several mechanical expanders (4) and partitions (5) are provided with end sleeves (3) at both ends.

10. A combined expansion clamping device for fixing a shaft according to claim 9, characterized in that, The expansion block (42) has expansion block chamfers (4203) at both ends. The expansion block chamfers (4203) are inclined surfaces or arc surfaces that are machined from the edge of the end face of the expansion block (42) inward, and are used to eliminate the sharp edges at both ends of the expansion block (42).

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