Hydraulic telescopic structure with movable sleeve and tailstock of numerical control lathe

Abstract

A hydraulic telescopic structure with movable sleeve and numerical control lathe tailstock, which relates to mechanical technology field, comprises tailstock body, movable sleeve assembly, sealing assembly and hydraulic drive system. The movable sleeve assembly is composed of outer sleeve and inner sleeve nesting, the outer sleeve adopts stepped design, the outer wall of the inner sleeve is provided with annular protrusion, which cooperates with the middle diameter part of the outer sleeve to form axial limiting. The bearing system comprises multiple groups of thrust ball bearings and double row cylindrical roller bearings, the thrust ball bearings are distributed at the front end and the rear end of the sleeve to bear the axial load, the double row cylindrical roller bearings are installed between the large diameter part and the inner sleeve to provide high radial stiffness support, and the pre-tightening force is adjusted through the locking nut to eliminate the play. The sealing assembly is composed of front end cover, elastic sealing ring and sleeve end cover, the front end cover and the sealing ring form a closed cavity to prevent the invasion of cutting chips and cooling liquid into the sleeve interior; the sleeve end cover and the rear bearing spacer further isolate the external pollutants, and protect the bearing and lubrication system.

Description

Technical Field

[0001] This utility model belongs to the field of mechanical technology, specifically a hydraulic telescopic structure with a movable sleeve and a tailstock for a CNC lathe. Background Technology

[0002] The core function of a traditional CNC lathe tailstock is to provide axial and radial support for the workpiece, ensuring stability during machining. Its typical structure includes a fixed sleeve, a standard live center, and a manual adjustment mechanism. During machining, the live center engages with the workpiece's center hole, and the workpiece is secured by the clamping force of the sleeve. However, while this design is sufficient for small to medium-sized workpieces, it is less suitable for machining large shaft-like workpieces. The live center typically uses single-row angular contact ball bearings or tapered roller bearings, which have limited radial load-bearing capacity.

[0003] When machining large workpieces, such as ship main shafts and wind turbine main shafts, the weight of the workpiece can reach tens of tons, which can cause the live center bearing to overload, leading to deformation or failure and seriously affecting machining accuracy. At the same time, the fixed sleeve provides passive support, and since the sleeve cannot rotate, the live center must independently bear the entire rotational load of the workpiece, further aggravating bearing wear and thermal deformation problems. Summary of the Invention

[0004] To address the problems of existing CNC lathe tailstocks not rotating with the workpiece and insufficient rigidity of standard movable centers when machining large workpieces, this invention proposes a hydraulic telescopic structure with a movable sleeve and a CNC lathe tailstock to solve these problems.

[0005] A hydraulic telescopic structure with a movable sleeve and a tailstock for a CNC lathe, including a tailstock body;

[0006] A movable sleeve assembly is installed inside the tailstock body. The movable sleeve assembly includes:

[0007] The outer sleeve includes a large-diameter portion, a first intermediate-diameter portion, a second intermediate-diameter portion, and a small-diameter portion.

[0008] Furthermore, it is divided into a large-diameter section, a first medium-diameter section, a second medium-diameter section, and a small-diameter section, and the load distribution is optimized through a stepped design.

[0009] Furthermore, the stepped outer sleeve distributes the load through different diameter segments, avoiding stress concentration; the annular protrusion of the inner sleeve cooperates with the outer sleeve to provide axial positioning and enhance overall rigidity.

[0010] The inner sleeve is located inside the outer sleeve; the outer surface of the inner sleeve is provided with annular protrusions, the position of which corresponds to the first middle diameter portion of the outer sleeve; the outer surface is provided with annular protrusions, which cooperate with the middle diameter portion of the outer sleeve to form a stable axial limit.

[0011] Furthermore, the inner sleeve can rotate relative to the outer sleeve, which solves the problem that the tailstock sleeve of existing lathes cannot rotate or that the standard movable center has insufficient strength. The two sets of double-row inner tapered roller bearings at the front and rear can withstand large radial loads, and the two sets of thrust ball bearings can withstand large axial loads. The bearing combination of this component effectively solves the defect of insufficient load-bearing capacity of the standard movable center. At the same time, the hydraulic cylinder at the rear end of the tailstock completes the automatic extension and retraction of the tailstock sleeve, which effectively expands the application range of the machine tool, improves the accuracy and stability of the machine tool when machining large parts, and also significantly improves production efficiency and product qualification rate.

[0012] Furthermore, the outer sleeve has an inner wall surface formed around the axis of the inner sleeve, and the inner sleeve has an outer wall surface formed around the axis of the inner sleeve, with the outer wall surface of the inner sleeve fitting into the inner wall surface of the outer sleeve.

[0013] The bearings include multiple sets of thrust ball bearings and double-row cylindrical roller bearings. The bearings are installed between the outer and inner wall surfaces to lock the inner sleeve inside the outer sleeve. The outer wall surface of the inner sleeve and the inner wall surface of the outer sleeve are connected by the bearings to achieve relative rotation and axial expansion and contraction.

[0014] Furthermore, the thrust ball bearing is distributed between the small diameter portion of the outer sleeve and the annular protrusion of the inner sleeve, as well as the second middle diameter portion at the rear end of the sleeve, and bears the axial load.

[0015] Furthermore, the double-row cylindrical roller bearing is installed between the large-diameter portion of the outer sleeve and the inner sleeve, providing high radial support.

[0016] Furthermore, the rear bearing spacer isolates the thrust ball bearing from the double-row roller bearing, optimizing the load transfer path.

[0017] Furthermore, the thrust ball bearing bears the axial force when the workpiece is clamped, while the double-row cylindrical roller bearing bears the radial force, thus avoiding overload of a single bearing.

[0018] Furthermore, the two rows of rollers in double-row cylindrical roller bearings significantly improve radial rigidity, making them particularly suitable for heavy-duty machining of large workpieces.

[0019] Furthermore, the bearing clearance is adjusted by tightening the rear lock nut to eliminate backlash during operation and ensure motion accuracy.

[0020] Furthermore, the inner sleeve and outer sleeve are connected by bearings and can rotate synchronously with the workpiece, replacing the passive support mode of the traditional live center and directly bearing the rotational load.

[0021] The dead tip is fitted inside the inner sleeve.

[0022] Furthermore, it also includes a sealing assembly, which includes a front end cap bolted to the end of the large-diameter portion of the outer sleeve; the front end cap is fitted onto the outer wall of the inner sleeve.

[0023] The front cover is fixed to the large-diameter part of the outer sleeve by bolts, and together with the sealing ring, it forms a closed cavity.

[0024] The sealing ring is located between the front cover and the inner sleeve. The upper surface of the sealing ring presses against the front cover, and the lower surface of the sealing ring presses against the inner sleeve.

[0025] The sealing ring is located between the front cover and the inner sleeve to prevent chips and coolant from entering the sleeve.

[0026] The first locking nut is located between the front end cover and the inner sleeve and is fitted onto the outer wall surface of the inner sleeve.

[0027] Furthermore, the sealing ring and the front cover form a double protection to prevent contaminants from damaging the bearing and extend its service life.

[0028] Furthermore, it also includes a front bearing gasket, which is located on the side of the outer sleeve with a large diameter near the first middle diameter of the outer sleeve, and the front bearing gasket is fitted onto the outer wall of the inner sleeve.

[0029] Furthermore, the first locking nut clamps the double-row cylindrical roller bearing and the front bearing pad, adjusting the bearing preload.

[0030] Furthermore, the combination of the lock nut and the bearing washer ensures uniform bearing preload, reducing vibration and misalignment during operation.

[0031] Furthermore, the double-row cylindrical roller bearing is clamped between the first locking nut and the front bearing pad, with one end of the double-row cylindrical roller bearing pressing against the first locking nut and the other end pressing against the front bearing pad.

[0032] Furthermore, a sleeve end cap is connected to the end of the second middle diameter section of the outer sleeve. Thrust ball bearings and double-row cylindrical roller bearings are sequentially installed inside the second middle diameter section of the outer sleeve along the direction away from the dead center. It also includes a rear bearing spacer, which is sandwiched between the thrust ball bearings and the double-row cylindrical roller bearings. The two ends of the rear bearing spacer press against the thrust ball bearings and the double-row cylindrical roller bearings, respectively.

[0033] Furthermore, it also includes a rear bearing spacer, with a second locking nut fitted onto the inner surface of the rear bearing spacer. The second locking nut is fitted onto the outer wall of the inner sleeve to lock the inner sleeve inside the outer sleeve.

[0034] Furthermore, the rear bearing spacer and the second lock nut are clamped between the double-row cylindrical roller bearing and the sleeve end cap to lock the double-row cylindrical roller bearing inside the outer sleeve.

[0035] Furthermore, it also includes a hydraulic cylinder, which is fixedly installed with the tailstock body, and the piston rod of the hydraulic cylinder extends into the outer sleeve and connects with the inner sleeve.

[0036] Furthermore, hydraulic drive replaces manual operation, enabling rapid and precise extension and retraction of the sleeve to adapt to different workpiece lengths and improve processing efficiency.

[0037] Furthermore, the guide key constrains the movement trajectory of the sleeve, and combined with the closed-loop control of the hydraulic system, ensures the repeatability accuracy of the clamping position.

[0038] Furthermore, guide keys and multiple oil cups are installed on the surface of the tailstock body.

[0039] Furthermore, a thrust ball bearing is sandwiched between the small-diameter portion of the outer sleeve and the annular protrusion, with the thrust ball bearing pressing against the annular protrusion.

[0040] During operation, the piston rod of the hydraulic cylinder is in a retracted state, the inner sleeve and the dead center retract into the outer sleeve, and the tailstock does not contact the workpiece.

[0041] The preload of the double-row cylindrical roller bearing is adjusted by using the first and second lock nuts to eliminate bearing clearance and ensure operational stability.

[0042] The hydraulic system starts, the CNC system sends a command, the hydraulic pump supplies oil to the hydraulic cylinder, the piston rod extends outward, pushing the inner sleeve to move linearly along the direction of the guide key.

[0043] The dead center clamps the workpiece, and the dead center at the front end of the inner sleeve contacts the center hole of the workpiece. The hydraulic system continuously applies pressure until the preset clamping force is reached, and then stops, thus completing the workpiece fixing.

[0044] The guide key constrains the movement trajectory of the inner sleeve, preventing deviation caused by uneven hydraulic thrust and ensuring precise alignment between the center point and the workpiece's central hole.

[0045] During the expansion and contraction process, double-row cylindrical roller bearings bear the radial load of the inner sleeve to prevent sleeve deformation.

[0046] The thrust ball bearing is located between the small diameter part of the outer sleeve and the annular protrusion of the inner sleeve. It bears the axial force when tightened and protects the double-row roller bearing from axial impact.

[0047] The lathe spindle drives the workpiece to rotate, and the dead center rotates synchronously with the workpiece.

[0048] Load transfer path: Radial load: The weight of the workpiece is transferred to the inner sleeve through the dead center, and then distributed to the outer sleeve and tailstock body by the double-row cylindrical roller bearing.

[0049] Axial load: The axial thrust generated by the cutting force is borne by the thrust ball bearing to prevent the sleeve from moving axially.

[0050] The high radial rigidity of double-row cylindrical roller bearings complements the axial load-carrying capacity of thrust ball bearings, forming a balanced distribution of multi-directional loads and ensuring machining stability.

[0051] The stepped design of the outer sleeve optimizes stress distribution and avoids localized overload.

[0052] The front cover and the sealing ring form a closed cavity to prevent chips and coolant from entering the sleeve; the sleeve end cover and the rear bearing spacer further isolate external contaminants and protect the bearing and lubrication system.

[0053] The elastic design of the sealing ring adapts to the expansion and contraction of the inner sleeve, maintaining a continuous sealing effect;

[0054] Regularly replenish grease to the oil cup to reduce bearing wear and extend service life;

[0055] Hydraulic retraction command: The CNC system sends a signal to release the workpiece, the hydraulic cylinder is depressurized, the piston rod drives the inner sleeve to retract, and the dead center is separated from the workpiece.

[0056] After the sleeve is fully retracted, the hydraulic system enters standby mode, waiting for the next processing cycle.

[0057] Hydraulic drive enables second-level extension and retraction response, improving efficiency compared to traditional manual adjustment;

[0058] The guide key and bearing preload design ensure repeatability that meets the requirements of high-precision machining.

[0059] The sleeve achieves rapid extension and retraction through a hydraulic drive system, while a multi-bearing collaborative design bears multi-directional loads. Sealing and guiding structures ensure motion accuracy and equipment lifespan. The workpiece load is supported by a closed-loop rigid support system via the dead center, inner sleeve, bearings, outer sleeve, and tailstock, avoiding the weak points of traditional live centers. The hydraulic system is integrated with CNC, supporting automated adjustment. The sealing design adapts to harsh machining environments. Suitable for large workpieces such as ship main shafts and wind turbine main shafts, it offers high machining accuracy.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1. Multi-bearing collaborative design to achieve balanced distribution of multi-directional loads.

[0062] The synergistic arrangement of thrust ball bearings and double-row cylindrical roller bearings significantly enhances the load-bearing capacity and stability of the tailstock. The double-row cylindrical roller bearings, with their two rows of rollers, provide high radial rigidity, capable of withstanding the weight and rotational loads of large workpieces, avoiding the overload failure issues common in traditional single-row bearings. The thrust ball bearings, distributed at the front and rear ends of the sleeve, are specifically designed to handle axial forces generated during machining, such as cutting thrust and clamping forces, effectively isolating the radial bearings from axial impacts. Adjustment of the rear bearing spacer and rear lock nut optimizes the load transfer path, ensuring controllable bearing clearance and eliminating running clearance, thereby significantly reducing vibration and misalignment. This split-load design not only extends bearing life but also improves machining accuracy, making it particularly suitable for heavy-duty, high-precision machining applications.

[0063] 2. Hydraulic drive and CNC integration enable efficient automated adjustment; traditional tailstocks rely on manual adjustment of the sleeve extension and retraction, which is inefficient and difficult to guarantee accuracy. This invention achieves rapid response and precise positioning by using a hydraulic cylinder to drive the sleeve extension and retraction, combined with the closed-loop control of a CNC system.

[0064] The hydraulic piston rod pushes the inner sleeve to move linearly along the guide key, ensuring that the center point is precisely aligned with the center hole of the workpiece, and the repeatability of the positioning accuracy can reach the micrometer level.

[0065] The guide key constrains the motion trajectory, avoiding deviation caused by uneven hydraulic thrust. At the same time, the CNC system can adjust the clamping force in real time to adapt to different workpiece lengths and processing requirements.

[0066] Compared with traditional manual operation, automated adjustment significantly shortens clamping time and improves processing efficiency, making it especially suitable for mass production and frequent changeovers of large workpieces.

[0067] 3. Stepped sleeve and sealing protection enhance structural rigidity and environmental adaptability.

[0068] The outer sleeve adopts a stepped design, which disperses stress through different diameter sections to avoid local overload. At the same time, the annular protrusion of the inner sleeve cooperates with the middle diameter part of the outer sleeve to form an axial limit, further enhancing the overall rigidity.

[0069] The sealing assembly consists of a front cover, an elastic sealing ring, and a sleeve end cover, forming a multi-layered protective barrier that effectively isolates contaminants such as chips and coolant from entering the sleeve, protecting the bearing and lubrication system. The elastic design of the sealing ring adapts to the expansion and contraction of the inner sleeve, ensuring a dynamic sealing effect. Furthermore, an oil cup on the tailstock body allows for periodic replenishment of grease, reducing friction and wear.

[0070] 4. Closed-loop rigid support and synchronous rotation improve machining stability.

[0071] Traditional live centers, due to passive support, require the bearings to independently bear the workpiece's rotational load, which easily leads to thermal deformation and wear. This invention utilizes a bearing connection between the inner and outer sleeves, allowing the inner sleeve and dead center to rotate synchronously with the workpiece, directly sharing the rotational load and forming a closed-loop rigid support system. Radial loads are distributed to the tailstock body via double-row cylindrical roller bearings, while axial loads are absorbed by thrust ball bearings. This balanced distribution of multi-directional loads significantly improves machining stability. Attached Figure Description

[0072] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0073] Figure 1 A sectional view of a hydraulic telescopic structure with a movable sleeve and a tailstock of a CNC lathe;

[0074] Figure 2 This is a sectional view of the movable sleeve assembly.

[0075] Figure 3 for Figure 2 Enlarged view of section A in the middle;

[0076] Figure 4 for Figure 2 Enlarged view of section B;

[0077] Figure 5 A partial sectional side view of a hydraulic telescopic structure with a movable sleeve and a tailstock of a CNC lathe;

[0078] Figure 6 This is a flowchart illustrating the operation of a hydraulic telescopic structure with a movable sleeve and a tailstock of a CNC lathe.

[0079] In the picture:

[0080] 1. Sleeve end cap;

[0081] 2. Rear bearing spacer;

[0082] 301. Thrust ball bearing; 302. Double row cylindrical roller bearing;

[0083] 4. Outer sleeve; 4a. Large diameter section of outer sleeve; 4b. First intermediate diameter section of outer sleeve; 4c. Second intermediate diameter section of outer sleeve;

[0084] 5. Front bearing gasket;

[0085] 6. Tighten the first lock nut;

[0086] 7. Sealing ring;

[0087] 8. Top-tier;

[0088] 9. Front cover;

[0089] 10. Screws;

[0090] 11. Inner sleeve;

[0091] 12. Rear bearing spacer;

[0092] 13. Second locking nut;

[0093] 14. Piston rod;

[0094] 15. Tail frame body;

[0095] 16. Guide keys;

[0096] 17. Hydraulic cylinder;

[0097] 18. Oil cup. Detailed Implementation

[0098] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0099] The application principle of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0100] Example 1

[0101] like Figure 1-4 As shown, a hydraulic telescopic structure with a movable sleeve includes a tailstock body 15.

[0102] A movable sleeve assembly is installed inside the tailstock body 15. The movable sleeve assembly includes:

[0103] The outer sleeve 4 includes a large diameter portion 4a, a first medium diameter portion 4b, a second medium diameter portion 4c, and a small diameter portion 4d.

[0104] It is divided into a large diameter section 4a, a first medium diameter section 4b, a second medium diameter section 4c, and a small diameter section 4d, and the load distribution is optimized through a stepped design.

[0105] The stepped outer sleeve 4 disperses the load through different diameter sections, avoiding stress concentration; the annular protrusion of the inner sleeve 11 cooperates with the outer sleeve 4 to provide axial positioning and enhance overall rigidity.

[0106] The inner sleeve 11 is located inside the outer sleeve 4; the outer surface of the inner sleeve 11 is provided with an annular protrusion, the position of which corresponds to the first middle diameter portion 4b of the outer sleeve; the outer surface is provided with an annular protrusion, which cooperates with the middle diameter portion 4b of the outer sleeve to form a stable axial limit.

[0107] The outer sleeve 4 has an inner wall surface formed around the axis of the inner sleeve 11, and the inner sleeve 11 has an outer wall surface formed around the axis of the inner sleeve 11. The outer wall surface of the inner sleeve 11 is sleeved with the inner wall surface of the outer sleeve 4.

[0108] The bearings include multiple sets of thrust ball bearings 301 and double-row cylindrical roller bearings 302. The bearings are installed between the outer wall surface and the inner wall surface to lock the inner sleeve 11 inside the outer sleeve 4. The outer wall surface of the inner sleeve and the inner wall surface of the outer sleeve are connected by the bearings to achieve relative rotation and axial expansion and contraction.

[0109] The thrust ball bearing 301 is distributed between the small diameter portion 4d of the outer sleeve and the annular protrusion of the inner sleeve, as well as the second medium diameter portion 4c at the rear end of the sleeve, and bears the axial load.

[0110] The double-row cylindrical roller bearing 302 is installed between the large-diameter portion 4a of the outer sleeve and the inner sleeve, providing high radial support.

[0111] Rear bearing spacer 12: isolates the thrust ball bearing from the double-row roller bearing, optimizing the load transfer path.

[0112] The thrust ball bearing 301 bears the axial force when the workpiece is clamped, and the double-row cylindrical roller bearing 302 bears the radial force, thus avoiding overload of a single bearing.

[0113] The two rows of rollers in the double-row cylindrical roller bearing 302 significantly improve radial rigidity, making it especially suitable for heavy-duty machining of large workpieces.

[0114] Adjust the bearing clearance by tightening the rear locking nut 13 to eliminate backlash during operation and ensure motion accuracy.

[0115] The inner sleeve 11 and the outer sleeve 4 are connected by bearings and can rotate synchronously with the workpiece, replacing the passive support mode of the traditional live center and directly bearing the rotational load.

[0116] Dead tip 8, dead tip 8 is fitted inside the inner sleeve 11.

[0117] Example 2

[0118] like Figure 1-5 As shown, based on Embodiment 1, a hydraulic telescopic structure with a movable sleeve further includes a sealing assembly. The sealing assembly includes a front cover 9, which is bolted to the end of the large-diameter portion 4a of the outer sleeve; the front cover 9 is sleeved on the outer wall surface of the inner sleeve 11.

[0119] The front cover (9) is fixed to the large diameter part (4a) of the outer sleeve by bolts, and cooperates with the sealing ring (7) to form a closed cavity.

[0120] The sealing ring 7 is located between the front end cover 9 and the inner sleeve 11. The upper surface of the sealing ring 7 presses against the front end cover 9, and the lower surface of the sealing ring 7 presses against the inner sleeve 11.

[0121] The sealing ring (7) is located between the front cover and the inner sleeve to prevent chips and coolant from entering the sleeve.

[0122] The first locking nut 6 is located between the front end cover 9 and the inner sleeve 11 and is sleeved on the outer wall surface of the inner sleeve 11.

[0123] The sealing ring 7 and the front cover 9 form a double protection to prevent contaminants from damaging the bearing and extend its service life.

[0124] It also includes a front bearing pad 5, which is located on the side of the outer sleeve large diameter portion 4a near the first middle diameter portion 4b of the outer sleeve, and the front bearing pad 5 is sleeved on the outer wall surface of the inner sleeve 11.

[0125] The first locking nut (6) clamps the double-row cylindrical roller bearing (302) and the front bearing pad (5) to adjust the bearing preload.

[0126] The combination of the lock nut and bearing washer ensures uniform bearing preload, reducing vibration and misalignment during operation.

[0127] The double-row cylindrical roller bearing 302 is clamped between the first locking nut 6 and the front bearing pad 5. One end of the double-row cylindrical roller bearing 302 presses against the first locking nut 6, and the other end presses against the front bearing pad 5.

[0128] The end of the second middle diameter section 4c of the outer sleeve is connected to a sleeve end cap 1. Inside the second middle diameter section 4c of the outer sleeve, a thrust ball bearing 301 and a double row cylindrical roller bearing 302 are installed in sequence along the direction away from the dead center. It also includes a rear bearing spacer 12, which is sandwiched between the thrust ball bearing 301 and the double row cylindrical roller bearing 302. The two ends of the rear bearing spacer 12 press against the thrust ball bearing 301 and the double row cylindrical roller bearing 302 respectively.

[0129] It also includes a rear bearing spacer 2, with a second locking nut 13 fitted onto the inner surface of the rear bearing spacer 2. The second locking nut 13 is fitted onto the outer wall of the inner sleeve 11 to lock the inner sleeve 11 inside the outer sleeve 4.

[0130] The rear bearing spacer 2 and the second locking nut 13 are clamped between the double-row cylindrical roller bearing 302 and the sleeve end cap 1 to lock the double-row cylindrical roller bearing 302 inside the outer sleeve 4.

[0131] It also includes a hydraulic cylinder 17, which is fixedly installed with the tailstock body 15. The piston rod 14 of the hydraulic cylinder 17 extends into the outer sleeve 4 and connects with the inner sleeve 11.

[0132] Hydraulic drive replaces manual operation, enabling rapid and precise extension and retraction of the sleeve, adapting to different workpiece lengths, and improving processing efficiency.

[0133] The guide key constrains the movement trajectory of the sleeve, and combined with the closed-loop control of the hydraulic system, ensures the repeatability accuracy of the clamping position.

[0134] The tailstock body 15 has guide keys 16 and multiple oil cups 18 mounted on its surface.

[0135] A thrust ball bearing 301 is sandwiched between the small diameter portion 4d of the outer sleeve and the annular protrusion, and the thrust ball bearing 301 presses against the annular protrusion.

[0136] Example 3

[0137] like Figure 1-6 As shown, a tailstock for a CNC lathe includes a tailstock body 15;

[0138] A movable sleeve assembly is installed inside the tailstock body 15. The movable sleeve assembly includes:

[0139] The outer sleeve 4 includes a large diameter portion 4a, a first medium diameter portion 4b, a second medium diameter portion 4c, and a small diameter portion 4d.

[0140] It is divided into a large diameter section 4a, a first medium diameter section 4b, a second medium diameter section 4c, and a small diameter section 4d, and the load distribution is optimized through a stepped design.

[0141] The stepped outer sleeve 4 disperses the load through different diameter sections, avoiding stress concentration; the annular protrusion of the inner sleeve 11 cooperates with the outer sleeve 4 to provide axial positioning and enhance overall rigidity.

[0142] The inner sleeve 11 is located inside the outer sleeve 4; the outer surface of the inner sleeve 11 is provided with an annular protrusion, the position of which corresponds to the first middle diameter portion 4b of the outer sleeve; the outer surface is provided with an annular protrusion, which cooperates with the middle diameter portion 4b of the outer sleeve to form a stable axial limit.

[0143] The outer sleeve 4 has an inner wall surface formed around the axis of the inner sleeve 11, and the inner sleeve 11 has an outer wall surface formed around the axis of the inner sleeve 11. The outer wall surface of the inner sleeve 11 is sleeved with the inner wall surface of the outer sleeve 4.

[0144] The bearings include multiple sets of thrust ball bearings 301 and double-row cylindrical roller bearings 302. The bearings are installed between the outer wall surface and the inner wall surface to lock the inner sleeve 11 inside the outer sleeve 4. The outer wall surface of the inner sleeve and the inner wall surface of the outer sleeve are connected by the bearings to achieve relative rotation and axial expansion and contraction.

[0145] The thrust ball bearing 301 is distributed between the small diameter portion 4d of the outer sleeve and the annular protrusion of the inner sleeve, as well as the second medium diameter portion 4c at the rear end of the sleeve, and bears the axial load.

[0146] The double-row cylindrical roller bearing 302 is installed between the large-diameter portion 4a of the outer sleeve and the inner sleeve, providing high radial support.

[0147] Rear bearing spacer 12: isolates the thrust ball bearing from the double-row roller bearing, optimizing the load transfer path.

[0148] The thrust ball bearing 301 bears the axial force when the workpiece is clamped, and the double-row cylindrical roller bearing 302 bears the radial force, thus avoiding overload of a single bearing.

[0149] The two rows of rollers in the double-row cylindrical roller bearing 302 significantly improve radial rigidity, making it especially suitable for heavy-duty machining of large workpieces.

[0150] Adjust the bearing clearance by tightening the rear locking nut 13 to eliminate backlash during operation and ensure motion accuracy.

[0151] The inner sleeve 11 and the outer sleeve 4 are connected by bearings and can rotate synchronously with the workpiece, replacing the passive support mode of the traditional live center and directly bearing the rotational load.

[0152] Dead tip 8, dead tip 8 is fitted inside the inner sleeve 11.

[0153] It also includes a sealing assembly, which includes a front cover 9, which is bolted to the end of the large diameter portion 4a of the outer sleeve; the front cover 9 is sleeved on the outer wall of the inner sleeve 11.

[0154] The front cover 9 is fixed to the large diameter part 4a of the outer sleeve by bolts, and cooperates with the sealing ring 7 to form a closed cavity.

[0155] The sealing ring 7 is located between the front end cover 9 and the inner sleeve 11. The upper surface of the sealing ring 7 presses against the front end cover 9, and the lower surface of the sealing ring 7 presses against the inner sleeve 11.

[0156] The sealing ring 7 is located between the front cover and the inner sleeve to prevent chips and coolant from entering the inside of the sleeve.

[0157] The first locking nut 6 is located between the front end cover 9 and the inner sleeve 11 and is sleeved on the outer wall surface of the inner sleeve 11.

[0158] The sealing ring 7 and the front cover 9 form a double protection to prevent contaminants from damaging the bearing and extend its service life.

[0159] It also includes a front bearing pad 5, which is located on the side of the outer sleeve large diameter portion 4a near the first middle diameter portion 4b of the outer sleeve, and the front bearing pad 5 is sleeved on the outer wall surface of the inner sleeve 11.

[0160] The first locking nut 6 clamps the double-row cylindrical roller bearing 302 and the front bearing pad 5, adjusting the bearing preload. The combination of the locking nut and the bearing pad ensures uniform bearing preload, reducing vibration and misalignment during operation.

[0161] The double-row cylindrical roller bearing 302 is clamped between the first locking nut 6 and the front bearing pad 5. One end of the double-row cylindrical roller bearing 302 presses against the first locking nut 6, and the other end presses against the front bearing pad 5.

[0162] The end of the second middle diameter section 4c of the outer sleeve is connected to a sleeve end cap 1. Inside the second middle diameter section 4c of the outer sleeve, a thrust ball bearing 301 and a double row cylindrical roller bearing 302 are installed in sequence along the direction away from the dead center. It also includes a rear bearing spacer 12, which is sandwiched between the thrust ball bearing 301 and the double row cylindrical roller bearing 302. The two ends of the rear bearing spacer 12 press against the thrust ball bearing 301 and the double row cylindrical roller bearing 302 respectively.

[0163] It also includes a rear bearing spacer 2, with a second locking nut 13 fitted onto the inner surface of the rear bearing spacer 2. The second locking nut 13 is fitted onto the outer wall of the inner sleeve 11 to lock the inner sleeve 11 inside the outer sleeve 4.

[0164] The rear bearing spacer 2 and the second locking nut 13 are clamped between the double-row cylindrical roller bearing 302 and the sleeve end cap 1 to lock the double-row cylindrical roller bearing 302 inside the outer sleeve 4.

[0165] It also includes a hydraulic cylinder 17, which is fixedly installed with the tailstock body 15. The piston rod 14 of the hydraulic cylinder 17 extends into the outer sleeve 4 and connects with the inner sleeve 11.

[0166] Hydraulic drive replaces manual operation, enabling rapid and precise extension and retraction of the sleeve, adapting to different workpiece lengths, and improving processing efficiency.

[0167] The guide key constrains the movement trajectory of the sleeve, and combined with the closed-loop control of the hydraulic system, ensures the repeatability accuracy of the clamping position.

[0168] The tailstock body 15 has guide keys 16 and multiple oil cups 18 mounted on its surface.

[0169] A thrust ball bearing 301 is sandwiched between the small diameter portion 4d of the outer sleeve and the annular protrusion, and the thrust ball bearing 301 presses against the annular protrusion.

[0170] During operation, the piston rod 14 of the hydraulic cylinder 17 is in a retracted state, the inner sleeve 11 along with the dead center 8 retracts into the outer sleeve 4, and the tailstock does not contact the workpiece.

[0171] The preload of the double-row cylindrical roller bearing 302 is adjusted by the first locking nut 6 and the second locking nut 13 to eliminate bearing clearance and ensure operational stability.

[0172] The hydraulic system is started, the CNC system sends a command, the hydraulic pump supplies oil to the hydraulic cylinder 17, the piston rod 14 extends outward, pushing the inner sleeve 11 to move linearly along the direction of the guide key 16.

[0173] The dead center clamps the workpiece, and the dead center 8 at the front end of the inner sleeve 11 contacts the center hole of the workpiece. The hydraulic system continuously applies pressure until the preset clamping force is reached, and then stops, thus completing the workpiece fixing.

[0174] The guide key 16 constrains the movement trajectory of the inner sleeve 11, avoiding deviation caused by uneven hydraulic thrust and ensuring precise alignment between the center point and the workpiece center hole.

[0175] During the expansion and contraction process, the double-row cylindrical roller bearing 302 bears the radial load of the inner sleeve 11 to prevent the sleeve from deforming.

[0176] The thrust ball bearing 301 is located between the small diameter portion 4d of the outer sleeve and the annular protrusion of the inner sleeve, bearing the axial force during clamping and protecting the double-row roller bearing from axial impact.

[0177] The lathe spindle drives the workpiece to rotate, and the dead center 8 rotates synchronously with the workpiece.

[0178] Load transfer path: Radial load: The weight of the workpiece is transferred to the inner sleeve 11 through the dead center 8, and then distributed to the outer sleeve 4 and the tailstock body 15 by the double row cylindrical roller bearing 302.

[0179] Axial load: The axial thrust generated by the cutting force is borne by the thrust ball bearing 301 to prevent the sleeve from moving axially.

[0180] The high radial rigidity of double-row cylindrical roller bearings complements the axial load-carrying capacity of thrust ball bearings, forming a balanced distribution of multi-directional loads and ensuring machining stability.

[0181] The stepped design of the outer sleeve 4 optimizes stress distribution and avoids local overload.

[0182] The front cover 9 and the sealing ring 7 form a closed cavity to prevent chips and coolant from entering the sleeve; the sleeve end cover 1 and the rear bearing spacer 2 further isolate external contaminants and protect the bearing and lubrication system.

[0183] The elastic design of the sealing ring 7 adapts to the expansion and contraction of the inner sleeve 11, maintaining a continuous sealing effect;

[0184] Oil cup 18 is regularly replenished with grease to reduce bearing wear and extend service life;

[0185] Hydraulic retraction command: The CNC system sends a signal to release the workpiece, the hydraulic cylinder 17 is depressurized, the piston rod 14 drives the inner sleeve 11 to retract, and the dead center 8 is separated from the workpiece.

[0186] After the sleeve is fully retracted, the hydraulic system enters standby mode, waiting for the next processing cycle.

[0187] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

[0188] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A hydraulic telescopic structure with a movable sleeve, characterized in that: Including the tail frame (15); A movable sleeve assembly, the movable sleeve assembly being installed inside the tailstock body (15), the movable sleeve assembly comprising; The outer sleeve (4) includes a large diameter portion (4a), a first medium diameter portion (4b), a second medium diameter portion (4c), and a small diameter portion (4d). Inner sleeve (11), the inner sleeve (11) is located inside the outer sleeve (4); the outer surface of the inner sleeve (11) is provided with an annular protrusion, the position of the annular protrusion corresponds to the first middle diameter part (4b) of the outer sleeve; The outer sleeve (4) has an inner wall surface formed around the axis of the inner sleeve (11), and the inner sleeve (11) has an outer wall surface formed around the axis of the inner sleeve (11). The outer wall surface of the inner sleeve (11) is sleeved with the inner wall surface of the outer sleeve (4).

2. A hydraulic telescopic structure with a movable sleeve according to claim 1, characterized in that: It also includes bearings, which include multiple sets of thrust ball bearings (301) and double-row cylindrical roller bearings (302), the bearings being installed between the outer wall surface and the inner wall surface to lock the inner sleeve (11) inside the outer sleeve (4), and a center (8) fitted inside the inner sleeve (11); it also includes a sealing assembly, which includes a front end cap (9) bolted to the end of the large diameter portion (4a) of the outer sleeve; the front end cap (9) is fitted onto the outer wall surface of the inner sleeve (11); A sealing ring (7) is located between the front end cover (9) and the inner sleeve (11). The upper surface of the sealing ring (7) presses against the front end cover (9), and the lower surface of the sealing ring (7) presses against the inner sleeve (11). The first locking nut (6) is located between the front end cover (9) and the inner sleeve (11) and is fitted onto the outer wall surface of the inner sleeve (11).

3. A hydraulic telescopic structure with a movable sleeve according to claim 2, characterized in that: It also includes a front bearing pad (5), which is located on the side of the outer sleeve large diameter portion (4a) near the first middle diameter portion (4b) of the outer sleeve, and the front bearing pad (5) is fitted onto the outer wall surface of the inner sleeve (11).

4. A hydraulic telescopic structure with a movable sleeve according to claim 3, characterized in that: The double-row cylindrical roller bearing (302) is clamped between the first locking nut (6) and the front bearing pad (5). One end of the double-row cylindrical roller bearing (302) presses against the first locking nut (6), and the other end presses against the front bearing pad (5).

5. The hydraulic telescopic structure with a movable sleeve according to claim 1, characterized in that: The end of the second middle diameter portion (4c) of the outer sleeve is connected to a sleeve end cap (1). Inside the second middle diameter portion (4c) of the outer sleeve, a thrust ball bearing (301) and a double row cylindrical roller bearing (302) are installed in sequence along the direction away from the dead center. It also includes a rear bearing spacer (12). The rear bearing spacer (12) is sandwiched between the thrust ball bearing (301) and the double row cylindrical roller bearing (302). The two ends of the rear bearing spacer (12) press against the thrust ball bearing (301) and the double row cylindrical roller bearing (302) respectively.

6. The hydraulic telescopic structure with a movable sleeve according to claim 5, characterized in that: It also includes a rear bearing spacer (2), on the inner surface of which a second locking nut (13) is fitted. The second locking nut (13) is fitted onto the outer wall of the inner sleeve (11) to lock the inner sleeve (11) inside the outer sleeve (4).

7. A hydraulic telescopic structure with a movable sleeve according to claim 6, characterized in that: The rear bearing spacer (2) and the second locking nut (13) are clamped between the double-row cylindrical roller bearing (302) and the sleeve end cap (1) to lock the double-row cylindrical roller bearing (302) inside the outer sleeve (4).

8. The hydraulic telescopic structure with a movable sleeve according to claim 1, characterized in that: It also includes a hydraulic cylinder (17), which is fixedly installed with the tailstock body (15). The piston rod (14) of the hydraulic cylinder (17) extends into the outer sleeve (4) and connects with the inner sleeve (11). The tailstock body (15) is equipped with a guide key (16) and multiple oil cups (18).

9. A hydraulic telescopic structure with a movable sleeve according to claim 1, characterized in that: A thrust ball bearing (301) is held between the small diameter portion (4d) of the outer sleeve and the annular protrusion, and the thrust ball bearing (301) presses against the annular protrusion.

10. A tailstock for a CNC lathe, characterized in that, The invention includes a hydraulic telescopic structure with a movable sleeve as described in any one of claims 1-9.

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