Piston-free guide rail guiding electric cylinder

Abstract

The piston-free type guide rail guiding electric cylinder structurally comprises a hollow cylindrical cylinder body, double-V-shaped anti-rotation groove linear guide rails which are symmetrically arranged, a multi-stage nested type rigid push rod, a ball screw driving assembly and a corrugated pipe sealing cover. Linear guide rails (the symmetric angle is 90-150 degrees) are symmetrically distributed on the outer surface of the cylinder body along the circumference, the cross section of each guide rail is of a double-V-shaped groove structure, the groove depth is 1 / 4-1 / 3 of the height of the cross section of the guide rail, the surface of each guide rail is coated with a silicon nitride-tungsten carbide composite ceramic layer (the thickness is 50-80 micrometers, and the microhardness is larger than or equal to 1500 HV), and the abrasion resistance and the deflection prevention capacity are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric cylinder production, and particularly to a pistonless guide rail-guided electric cylinder. Background Art

[0002] In the fields of industrial automation and precision manufacturing, linear drive devices (such as electric cylinders) are the core components for achieving high-precision positioning and load driving. Traditional electric cylinders mostly adopt piston-type structures, and achieve linear motion through the cooperation of piston rods and seals. However, they have the following significant defects: 1. Easy seal wear and short lifespan The sliding friction between the piston and the cylinder body causes the sealing rings (such as O-rings, lip seals) to wear rapidly. Especially during high-speed or high-frequency reciprocating motions, the risk of seal failure increases significantly. According to statistics, after the traditional piston electric cylinder operates continuously for 1000 hours, the wear amount of the seal can reach more than 0.5 mm, and it is necessary to frequently stop the machine for replacement, resulting in high maintenance costs.

[0003] 2. Uncontrollable transmission clearance It is difficult to completely eliminate the clearance between the piston rod and the cylinder body and the backlash of the drive components (such as ball screws), resulting in limited positioning accuracy.

[0004] 3. Insufficient stability of multi-stage push rods Existing telescopic push rods mostly adopt single-stage or simple nested structures, and there is a lack of effective guiding and locking mechanisms between stages. Under sudden load changes or vibration conditions, the push rod is prone to radial yaw (yaw angle > 0.1°) or axial looseness, resulting in end positioning drift. In addition, traditional mechanical locking mechanisms (such as plug-in type) are cumbersome to operate, with a large unlocking force (≥20 N), and it is difficult to meet the rapid response requirements of automated equipment.

[0005] 4. Poor environmental adaptability The sealing structure of traditional electric cylinders is mostly a fixed dust cover, which cannot dynamically adapt to the large-stroke telescoping of the push rod and lacks a pneumatic balance design. In environments with drastic temperature changes (such as -40°C to 120°C) or dusty conditions, the pressure difference inside and outside the cylinder is likely to cause seal failure, or the intrusion of external pollutants will exacerbate wear.

[0006] In recent years, some improved guide rail-guided electric cylinders have replaced the piston structure with linear guide rails. Although the motion stability has been improved to a certain extent, there are still the following problems: 1. Insufficient anti-rotation ability: The contact surfaces of single V-shaped or flat guide rails are single, and they cannot effectively resist torque loads. The slider is prone to deflection under asymmetric loads; 2. High maintenance complexity: The sealing covers of the guide rail and the slider are mostly fixed with bolts, and special tools are required for disassembly. The maintenance time > 10 minutes; 3. Dynamic response lag: Lack of an intelligent air pressure regulation system, unable to compensate in real time for the impact of temperature or pressure fluctuations on transmission accuracy.

[0007] To address the above problems, a new type of pistonless guide rail-guided electric cylinder is urgently needed, which should have the following characteristics: High precision and high rigidity: Eliminate transmission clearance, achieve a positioning accuracy of ±0.01 mm, and an anti-deflection torque ≥ 50 N·m; Long life and low maintenance: The wear resistance of key moving pairs is increased by more than 3 times, and the maintenance cycle > 6 months; Environmental adaptability: Support a wide temperature range (-40°C to 120°C) and a dusty environment, and the dynamic sealing and air pressure regulation system compensates in real time for changes in working conditions; Operation convenience: The modular design supports quick disassembly and assembly, the operating force of the unlocking mechanism ≤ 5 N, and it is adapted to automated control.

[0008] The present invention precisely proposes an innovative solution under this background. Summary of the Invention

[0009] To overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a pistonless guide rail-guided electric cylinder.

[0010] To achieve the above object, the innovation points of the present invention are as follows: Its structure includes: A hollow cylindrical cylinder body, whose inner cavity is sealed and at least two linear guide rails are symmetrically arranged along the circumferential direction on the outer surface. The symmetrical distribution angle of the linear guide rails is 90° - 150°. The cross-section of each linear guide rail is a double-V anti-rotation groove, which is composed of two adjacent V-shaped grooves. The groove depth of the V-shaped groove is 1 / 4 - 1 / 3 of the height of the guide rail cross-section; A slider assembly that slidably cooperates with the linear guide rail. The slider assembly is connected to an external load through a multi-stage nested rigid push rod. Needle bearings are provided between adjacent stages of the rigid push rod, and a self-locking limit buckle is integrated on the outer wall of the last-stage rigid push rod; A drive assembly, including a ball screw that penetrates the cylinder body, a nut that is threadedly engaged with the ball screw, and a backlash eliminator coupling that connects the nut and the slider assembly; A bellows seal cover that covers the movement area of the linear guide rail and the slider assembly, and has quick-release clamps at both ends and the surface of the cylinder body.

[0011] Further, the slider assembly includes: A slider body, which is internally provided with a double-V flange that matches the double-V anti-rotation groove; A drive interface, which is provided at the front end of the slider body and is used to fix one end of the backlash eliminator coupling; A connection base, which is provided at the rear end of the slider body and is fixed to the last-stage rigid push rod through a thread or a flange; The installation groove is integrated on the side of the slider body and is used for installing the displacement sensor. A detection target is provided on the outer surface of the cylinder body. The displacement sensor and the detection target are arranged in parallel on the outer surface of the cylinder body, and the detection accuracy is ±0.01 mm; Further, a through notch is axially formed on the side wall of the cylinder body. The backlash eliminator coupling passes through the notch to connect the nut and the drive interface, and the bellows seal cover covers the outside of the notch.

[0012] Further, the self-locking limit buckle includes a one-way ratchet rack and a pawl. The pawl is hinged to the inner wall of the rigid push rod through a hinge shaft, and a return spring is provided at the end of the pawl and meshes with the one-way ratchet rack under normal conditions; The unlocking handle is arranged on the outer surface of the outermost rigid push rod. The unlocking handle is provided with a rotating shaft, the pawl is provided with a driving arm, the unlocking handle is connected to the pawl through a rigid connecting rod, one end of the rigid connecting rod is fixed to the rotating shaft, and the other end is hinged to the driving arm through a pin; When the unlocking handle is rotated, the rigid connecting rod pushes the driving arm, forcing the pawl to rotate around the hinge shaft and disengage from the one-way ratchet rack, realizing the unlocking and retraction of the rigid push rod; The rotation angle of the unlocking handle ≤ 30°, and the unlocking force ≤ 5 N.

[0013] Further, the symmetric distribution angle of the linear guide rail is 120° ± 5°, and the surface is coated with a silicon nitride-tungsten carbide composite ceramic layer with a thickness of 50 - 80 μm and a microhardness ≥ 1500 HV.

[0014] Further, preloaded angular contact bearings are arranged at both ends of the ball screw, and the preload adjustment range is 5 - 20 N·m.

[0015] Further, the fold expansion ratio of the bellows seal cover is not less than 1.2 times the maximum stroke of the slider assembly, and the inner wall is coated with a nano oil-repellent coating with a contact angle ≥ 150°.

[0016] Further, an end cover is provided at the end of the cylinder body. The end cover is provided with a pneumatic balance valve. The inner cavity of the cylinder body is filled with argon or nitrogen, and the pressure is maintained at 0.1 - 0.3 MPa through the pneumatic balance valve.

[0017] Further, the slider assembly integrates a displacement sensor. A detection target is provided on the outer surface of the cylinder body. The displacement sensor and the detection target are arranged in parallel on the outer surface of the cylinder body, and the detection accuracy is ±0.01 mm.

[0018] Further, the radial clearance of the needle bearing is 0.01 - 0.03 mm, and the outer ring is plated with a diamond-like carbon film.

[0019] The beneficial effects of the present invention are: 1. Precision and stability The backlash elimination coupling and the preloaded bearing work together, with a reverse clearance ≤ 2μm and a positioning repeatability accuracy of ±0.01mm.

[0020] The symmetric layout of the double V-shaped guide rails enables the yaw angle of the slider to be < 0.01°.

[0021] 2. Service Life and Reliability After 100,000 cycles of testing, the wear of the composite ceramic layer is < 1μm, and its service life is 5 times that of traditional steel guide rails.

[0022] The friction power consumption of the DLC-coated needle roller bearing is reduced by 60%, and the temperature rise is < 10℃.

[0023] 3. Maintenance Convenience The quick-release clamp enables the sealing cover to be replaced within ≤ 3 minutes, and the operating force of the unlocking handle is ≤ 5N, suitable for single-person maintenance. Description of the Drawings

[0024] Figure 1 This is a schematic side view of the electric cylinder of the present invention.

[0025] Figure 2 This is a structural diagram of the matching of the double V-shaped anti-rotation groove and the double V-shaped flange of the present invention.

[0026] Figure 3 This is a detailed connection diagram of the pawl and the rigid link of the self-locking limit buckle of the present invention. Detailed Embodiment

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] As Figures 1 to 3 This is a specific embodiment of the present invention, in which, The core structure of the electric cylinder is as follows: 1. The hollow cylindrical cylinder block 101 and the linear guide rail 104 Structural Design: The cylinder block 101 is made of high-strength aluminum alloy or carbon fiber composite material, and its inner cavity is precisely machined to ensure airtightness. At least two linear guide rails 104 are symmetrically arranged along the circumferential direction of the outer surface, and the symmetric angle is 90° - 150° (preferably 120° ± 5°). The cross-section of each linear guide rail 104 is a double V-shaped anti-rotation groove, which is composed of two adjacent V-shaped grooves 100, and the groove depth is 1 / 4 - 1 / 3 of the height of the guide rail cross-section.

[0029] Anti-rotation Mechanism: The double V-groove 100 makes multi-point contact with the corresponding flange 201b on the slider assembly 201, and restricts the degree of freedom of the slider body 201a to rotate around the axis through geometric constraints. When the slider body 201a moves, the flange 201b contacts the inclined surface of the double V-groove 100, generating a normal force that is decomposed into axial and radial components. The radial component is offset by symmetrically distributed guide rails, thereby eliminating the deflection moment.

[0030] Material optimization: The surface of the linear guide rail is coated with a silicon nitride-tungsten carbide composite ceramic layer 104a, with a thickness of 50 - 80 μm and a microhardness of ≥1500 HV. The ceramic layer is prepared by plasma spraying process, with a bonding strength of ≥80 MPa, significantly improving wear resistance and impact resistance.

[0031] Slider assembly 201 and rigid push rod 202 Multi-stage nested rigid push rod 202: The rigid push rod 202 is made of high-strength titanium alloy and adopts a multi-stage nested structure. Needle roller bearings 202c (radial clearance 0.01 - 0.03 mm) are arranged between stages. The outer ring of the needle roller bearing is coated with diamond-like carbon film (DLC), with a friction coefficient <0.1 and a service life of up to 1 million cycles.

[0032] Self-locking limit buckle 202a: On the outer wall of the last-stage rigid push rod 202, a one-way ratchet rack 202a1 and a spring-loaded pawl 202a2 are integrated. The pawl 202a2 is hinged to the inner wall of the rigid push rod 202 through a hinge shaft 202a3. The return spring 202a4 provides a pre-tightening force of 3 - 5 N to ensure that the pawl 202a2 meshes with the one-way ratchet rack 202a1 under normal conditions. When unlocking, the external handle 202d drives the pawl 202a2 to disengage through the rigid link 202d1.

[0033] Drive assembly Ball screw 303 and backlash eliminator coupling 304a: The ball screw 303 is manufactured by precision grinding process, with a lead error of ≤5 μm / 300 mm. The nut 304 is connected to the slider assembly 201 through the backlash eliminator coupling 304a. The backlash eliminator coupling 304a adopts a diaphragm structure, compensating for axial and radial deviations through elastic deformation and eliminating backlash.

[0034] Preloaded angular contact bearing 303a: The preload of the angular contact bearing 303a can be adjusted in the range of 5 - 20 N·m. The preload is precisely controlled by adjusting the thickness of the spacer sleeve inside the inner ring of the angular contact bearing 303a to ensure the axial rigidity of the ball screw 303.

[0035] Bellows seal cover 401 Dynamic seal design: The bellows seal cover 401 is made of fluororubber, and the pleat expansion ratio is ≥ 1.2 times the maximum stroke of the slider, ensuring that the bellows seal cover 401 will not be stretched and broken when the push rod expands and contracts. The inner wall is coated with a nano oil-repellent coating (401d) with a contact angle ≥ 150° to prevent oil stains from adhering.

[0036] Quick-release clamp 401a: The clamp 401a is made of stainless steel and is quickly locked through an eccentric wheel handle, with a disassembly time ≤ 30 seconds.

[0037] The structure based on the core structure of the electric cylinder is as follows: Linear guide 104 and composite ceramic layer Improved anti-rotation ability: The symmetrical layout of the double V-grooves (120° ± 5°) makes the force on the slider uniform. Combining with the high hardness of the composite ceramic layer, the friction coefficient is reduced to 0.05 - 0.1 (the traditional steel guide is 0.15 - 0.2).

[0038] Optimized wear resistance: The mass ratio of silicon nitride (Si3N4) to tungsten carbide (WC) is 7:3, and a dense composite layer is formed through high-temperature sintering. The microhardness reaches 1600HV, and the wear rate < 0.1mg / 10km travel.

[0039] Self-locking limit buckle and unlocking mechanism Force transmission efficiency: The rigid connecting rod 202d1 adopts the lever principle. The force arm ratio of the driving arm 202a5 to the hinge shaft 202a3 is 1:2.5, the unlocking force ≤ 5N, and the handle rotation angle ≤ 30°.

[0040] Wear-resistant design: The contact surface between the one-way ratchet rack 202a1 and the pawl 202a2 is plated with hard chromium (thickness 20 - 30μm, hardness ≥ 800HV), and the cycle life > 100,000 times.

[0041] Dynamic air pressure regulation system Pressure closed-loop control: The cylinder body is filled with argon (purity ≥ 99.99%). The air pressure balance valve 102a monitors the pressure fluctuation in real time. When the deviation exceeds ±0.02MPa, the air pressure balance valve 102a opens to supplement or exhaust air, and the response time ≤ 0.1s.

[0042] Displacement detection system High-precision sensing: The displacement sensor 501 adopts the magnetic grating principle. The detection target 502 is arranged in parallel on the outer surface of the cylinder body, with a resolution of 0.1μm and a detection accuracy of ±0.01mm. Example 1

[0043] Cylinder block and linear guide assembly: An aluminum alloy is used to machine a hollow cylindrical cylinder block 101, and linear guides 104 are symmetrically arranged along the circumferential direction of the outer surface at 120°. The depth of the double V-groove is 1 / 3 of the height of the linear guide. A silicon nitride-tungsten carbide composite ceramic layer (with a thickness of 60 μm and a hardness of 1600 HV) is plasma-sprayed on the surface of the linear guide.

[0044] Slider assembly 201 assembly: Pre-assemble backlash eliminator coupling 304a: Align the flange end of the pre-assembled backlash eliminator coupling 304a with the drive interface 201c, insert a positioning pin (Φ3mm, H7 tolerance), and gradually tighten the bolts to 10 N·m. The coaxiality calibration is ≤0.01 mm (detected using a dial indicator).

[0045] Install onto linear guide 104: Apply low-friction grease (Kluber ISOFLEX NBU 15) on the surface of the double V-flange 201b, and manually push the slider assembly 201 along the guide to test that the resistance is ≤5 N.

[0046] Rigid push rod 202 connection and self-locking test: Screw the rigid push rod 202 at the end stage into the connection base 201e, apply a torque of 30 N·m, and check for no looseness. Manually operate the unlocking handle 202d to verify that the push rod retracts smoothly when the pawl 202a2 disengages, and there is no gap when it is reset and engaged.

[0047] Drive assembly installation: Preloaded angular contact bearings 303a are installed at both ends of the ball screw 303, and the preload is adjusted to 12 N·m. The nut 304 is connected to the slider assembly 201 through the backlash eliminator coupling 304a and passes through the cylinder block notch (width 8 mm).

[0048] Rigid push rod and self-locking limit buckle: Needle bearings (202c, radial clearance 0.02 mm) coated with DLC are arranged between adjacent stages of the rigid push rod 202. A self-locking buckle 202a is installed on the outer wall of the rigid push rod 202 at the end stage, and the unlocking handle 202d drives the pawl to disengage through the rigid link 202d1.

[0049] Sealing and air pressure control: A nano-oil-repellent coating (contact angle 155°) is coated on the inner wall of the bellows seal cover 401, and it is locked with a quick-release clamp. The cylinder body is filled with nitrogen to 0.2 MPa, and the response time of the air pressure balance valve 102a is ≤0.1 s. Example 2

[0050] Semiconductor wafer handling robotic arm Load conditions: handling weight 5 kg, stroke 500 mm, speed 1 m / s; Test results: positioning accuracy: ±0.008 mm (better than the design requirements), continuous operation for 6 months without failure, and the maintenance frequency is reduced from 2 times per month to 1 time per quarter. Example 3

[0051] High and low temperature environment test Operating conditions: start at -40°C low temperature, continuous operation at 120°C high temperature; Results: the dynamic regulation pressure error of the pneumatic balance valve < ±0.01 MPa; There is no oil stain adhesion on the nano oleophobic coating 401d, and the sealing cover extends and retracts without jamming.

[0052] Finally, the following points should be noted: First, in the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, which can be a mechanical connection or an electrical connection, or the communication inside two components, and can be directly connected. The terms "upper", "lower", "left", "right", etc. are only used to represent the relative position relationship. When the absolute position of the object being described changes, the relative position relationship may change; Second: In the attached drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved. For other structures, reference can be made to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other; Finally: The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pistonless guide rail-guided electric cylinder, characterized in that: Its structure includes: A hollow cylindrical cylinder (101) has a sealed inner cavity and an outer surface symmetrically arranged with at least two linear guide rails (104) along the circumferential direction, wherein the symmetrical distribution angle of the linear guide rails (104) is 90°-150°, and the cross section of each linear guide rail (101) is a double V-shaped anti-rotation groove, wherein the double V-shaped anti-rotation groove is composed of two adjacent V-shaped grooves (100), and the groove depth of the V-shaped groove (100) is 1 / 4-1 / 3 of the guide rail cross section height; A slider assembly (201) slidably engaged with the linear guide rail (104), the slider assembly (201) being connected to an external load via a multi-stage nested rigid push rod (202), needle bearings (202c) being provided between adjacent stages of the rigid push rod (202), and a self-locking limit buckle (202a) being integrated on the outer wall of the rigid push rod (202) at the final stage; A drive assembly comprising a ball screw (303) passing through the cylinder body (101), a nut (304) threadedly engaged with the ball screw (303), and an anti-backlash coupling (304a) connecting the nut (304) and the slider assembly (201); The bellows sealing cover (401) covers the motion area of the linear guide rail (104) and the slider assembly (201), and has quick-detachable clamps (401a) at both ends and on the surface of the cylinder body (101).

2. The pistonless guide rail-guided electric cylinder according to claim 1, wherein The slider assembly (201) comprises: a slider body (201a), the interior of which is provided with a double V-shaped flange (201b) matching the double V-shaped anti-rotation groove; A drive interface (201c) is provided at the front end of the slider body (201a) and is used to fix one end of the anti-backlash coupling (304a); A connecting base (201e) is provided at the rear end of the slider body (201a) and is fixed to the rigid push rod (202) of the final stage via a thread or a flange; The mounting groove (201d) is integrated into the side of the slider body (201a) and is used to mount a displacement sensor (501). A detection target (502) is provided on the outer surface of the cylinder body (101). The displacement sensor (501) detects that the target (502) is arranged parallel to the outer surface of the cylinder body, with a detection accuracy of ±0.01 mm.

3. The pistonless guide rail-guided electric cylinder according to claim 2, wherein, A through slot (105) is provided in the side wall of the cylinder body (101) along the axial direction, the anti-backlash coupling (304a) passes through the slot (105) to connect the nut (304) and the drive interface (201c), and the outside of the slot (105) is covered with the bellows sealing cover (401).

4. The pistonless guide rail-guided electric cylinder according to claim 1, wherein, The self-locking limiting buckle (202a) comprises a one-way ratchet bar (202a1) arranged at the end of each level of the rigid push rod (202) and a pawl (202a2) arranged on the inner wall of the adjacent rigid push rod (202), the one-way ratchet bar (202a1) being arranged axially along the rigid push rod (202), the pawl (202a2) being hinged to the inner wall of the rigid push rod (202) via a hinge shaft (202a3), and a return spring (202a4) being provided at the end of the pawl (202a2), which is in normal state and meshes with the one-way ratchet bar (202a1); The unlocking handle (202d) is arranged on the outer surface of the outermost rigid push rod (202). The unlocking handle (202d) is provided with a rotating shaft (202d2). A driving arm (202a5) is provided on the pawl (202a2). The unlocking handle (202d) is connected to the pawl (202a2) through a rigid connecting rod (202d1). One end of the rigid connecting rod (202d1) is fixed to the rotating shaft (202d2), and the other end is hinged to the driving arm (202a5) through a pin (202d3). When the unlocking handle (202d) is rotated, the rigid connecting rod (202d1) pushes the driving arm (202a5), forcing the pawl (202a2) to rotate around the hinge shaft (202a3) and disengage from the one-way ratchet rack (202a1), realizing the unlocking and retraction of the rigid push rod (202). The rotation angle of the unlocking handle (202d) ≤ 30°, and the unlocking force ≤ 5 N.

5. A pistonless guide rail-guided electric cylinder according to claim 1, characterized in that, The symmetric distribution angle of the linear guide (104) is 120° ± 5°, and its surface is coated with a silicon nitride-tungsten carbide composite ceramic layer (104a) with a thickness of 50 - 80 μm and a microhardness ≥ 1500 HV.

6. The pistonless guide rail-guided electric cylinder according to claim 1, characterized in that, Preloaded angular contact bearings (303a) are arranged at both ends of the ball screw (303), and the preload adjustment range is 5 - 20 N·m.

7. The pistonless guide rail-guided electric cylinder according to claim 1, characterized in that, The corrugated telescopic ratio of the bellows seal cover (401) is not less than 1.2 times the maximum stroke of the slider assembly (201), and its inner wall is coated with a nano oleophobic coating (401d) with a contact angle ≥ 150°.

8. The pistonless guide rail-guided electric cylinder according to claim 1, characterized in that, An end cover (102) is provided at the end of the cylinder block (101). The end cover (102) is provided with a pneumatic balance valve (102a). The inner cavity of the cylinder block (101) is filled with argon or nitrogen, and the pressure is maintained at 0.1 - 0.3 MPa through the pneumatic balance valve (102a).

9. The pistonless guide rail-guided electric cylinder according to claim 1, characterized in that, The slider assembly (201) is integrated with a displacement sensor (501). A detection target (502) is provided on the outer surface of the cylinder block (101). The displacement sensor (501) detects the target (502) arranged in parallel on the outer surface of the cylinder block with a detection accuracy of ±0.01 mm.

10. The pistonless guide rail-guided electric cylinder according to claim 1, wherein The radial clearance of the needle bearing (202c) is 0.01 - 0.03 mm, and its outer ring is plated with a diamond-like carbon film.

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