CN118554688B - A two-stage precision electric cylinder based on a reverse planetary roller screw - Google Patents

Abstract

A two-stage precision electric cylinder based on a reverse planetary roller screw relates to the field of electric cylinders. A two-stage precision electric cylinder based on a reverse planetary roller screw comprises a cylinder body, a first power assembly, a second power assembly, a bearing group, a first-stage reverse planetary roller screw subassembly and a second-stage reverse planetary roller screw subassembly. The present invention adopts a two-stage reverse planetary roller screw subassembly design, which can withstand higher loads, ensure high transmission efficiency, low heat generation and long service life; adopts a frameless torque motor to ensure direct transmission and efficient operation of driving force, minimizes axial and radial dimensions, and makes the structure more compact and easy to integrate; two frameless torque motors are used to drive two-stage long nuts respectively, and two annular magnetic encoders are used to detect the status of the motors, thereby realizing separate precision control of the two stages and allowing the two stages to achieve synchronous or independent movement, thereby adapting to complex application occasions.

Description

A two-stage precision electric cylinder based on a reverse planetary roller screw

Technical Field

The invention relates to the field of electric cylinders, and in particular to a two-stage precision electric cylinder based on a reverse planetary roller screw.

Background Art

Smart manufacturing has become a key force in promoting industrial upgrading and enhancing competitiveness. As a precision core component, electric cylinders, with their unique advantages, have made important contributions to the construction of smart factories. The application of electric cylinders in precision positioning and handling has significantly improved production efficiency. In the fields of semiconductor manufacturing, electronic assembly, etc., the requirements for precision are extremely high, and traditional mechanical transmission methods are difficult to meet the requirements. The electric cylinder, with its micron-level control accuracy, can ensure the precise handling and positioning of parts, thereby ensuring product quality and improving production efficiency. In smart factories, it is often encountered that the installation space is limited but a long working stroke is required, or the working stroke requirements change frequently. Although the single-stage electric cylinder can meet the requirements of small installation space, it cannot meet the needs of working stroke. If the stroke of the single-stage electric cylinder is extended, it will become bulky and require a larger installation space. At the same time, it may cause unstable work, which will affect the transmission speed, working accuracy and service life.

The existing two-stage or more multi-stage electric cylinder motor device is usually located at one end or top of the cylinder body, and is connected to the screw or other transmission components in the cylinder body through various power transmission mechanisms (such as reducers, synchronous wheel transmission assemblies, gears, etc.). This will cause the axial and radial dimensions of the overall structure of the multi-stage electric cylinder to be larger. The introduction of the transmission mechanism will also increase the complexity of the structure and affect the transmission efficiency.

Existing multi-stage electric cylinders with two or more levels use trapezoidal screws or ball screws, which may heat up when subjected to high loads or running for a long time. As the temperature rises, it may not only cause thermal expansion of the screw and related components, affecting mechanical accuracy, but also accelerate component wear and increase system noise and vibration. Under high loads, the dynamic response and stability of the screw may also decrease, affecting the overall motion performance.

Summary of the invention

The purpose of the present invention is to solve the existing problems described in the background technology and to provide a two-stage precision electric cylinder based on a reverse planetary roller screw.

A two-stage precision electric cylinder based on a reverse planetary roller screw comprises a cylinder body, a first power assembly, a second power assembly, a bearing group, a first-stage reverse planetary roller screw subassembly and a second-stage reverse planetary roller screw subassembly;

The cylinder body comprises a front end cover, a shell and a rear end cover;

The first power assembly comprises a first frameless torque motor stator, a first frameless torque motor rotor, a first annular magnetic encoder stator and a first annular magnetic encoder rotor;

The second power assembly comprises a second frameless torque motor stator, a second frameless torque motor rotor, a second annular magnetic encoder stator and a second annular magnetic encoder rotor;

The bearing group comprises a first bearing, a second bearing, a third bearing and a fourth bearing;

The two-stage reverse planetary roller screw subassembly comprises a two-stage long nut, a two-stage planetary roller, a two-stage support frame, a two-stage retaining ring, a two-stage screw and a second guide rail;

The front cover and the shell body, and the rear cover and the shell body are connected by screws, and flanges are provided at the connection between the front cover and the shell body, and at the connection between the rear cover and the shell body, so that the front cover and the rear cover and the shell body are embedded and connected;

One end of the first frameless torque motor stator abuts against a protrusion on the inner wall of the shell and is fixed to the inner wall of the shell by structural adhesive, one end of the first frameless torque motor rotor abuts against a protrusion on the first-level long nut and is fixed to the outer wall of the first-level long nut by structural adhesive, the first annular magnetic encoder stator is fixedly mounted on the inner wall of the rear end cover by screws, the first annular magnetic encoder rotor is fixedly connected to the first-level long nut by a set screw, and the axis of the first annular magnetic encoder rotor coincides with the axis of the first annular magnetic encoder stator;

One end of the second frameless torque motor stator abuts against the protrusion of the inner wall of the second frameless torque motor fixing member and is fixed to the inner wall of the second frameless torque motor fixing member by structural adhesive, one end of the second frameless torque motor rotor abuts against the protrusion of the solid part of the secondary long nut and is fixedly connected to the outer wall of the solid part of the secondary long nut by structural adhesive, the second annular magnetic encoder stator is fixedly mounted on the inner wall of the rear end cover of the primary hollow screw by screws, the second annular magnetic encoder rotor is fixedly connected to the secondary long nut by a set screw, and the axis of the second annular magnetic encoder rotor coincides with the axis of the second annular magnetic encoder stator;

The outer wall of the first bearing is matched and connected with the inner wall of the housing part, the outer wall of the second bearing is matched and connected with the inner wall of the rear end cover part, the first bearing and the second bearing are symmetrically arranged at both ends of the first-stage long nut for support and positioning, ensuring that the air gap between the first frameless torque motor stator and the first frameless torque motor rotor is uniform and the axial position is correctly matched, the outer walls of the third bearing and the fourth bearing are matched and connected with the inner wall of the first-stage hollow screw part, and the inner walls are symmetrically arranged at both ends of the second-stage long nut for support and positioning, so that the air gap between the second frameless torque motor stator and the second frameless torque motor rotor is uniform and the axis lines coincide;

A primary support frame is arranged on the primary hollow lead screw, two ends of the primary planetary roller are respectively connected to the primary support frame, the primary planetary roller is threadedly connected to the primary long nut, the primary hollow lead screw is threadedly connected to the primary planetary roller, a primary retaining ring is fixedly arranged on the outer wall of the primary hollow lead screw to fix the primary support frame, the track of the first guide slide rail is arranged on the outer wall of the primary hollow lead screw, the keyway of the first guide slide rail is arranged inside the front end cover, the front end cover of the primary hollow lead screw and the second frameless torque motor fixing piece are connected to the primary hollow lead screw by screws, the rear end cover of the primary hollow lead screw is connected to the second frameless torque motor fixing piece by screws, and flanges are arranged at the connection between the front end cover of the primary hollow lead screw and the second frameless torque motor fixing piece, so that the front end cover of the primary hollow lead screw and the second frameless torque motor fixing piece are embedded and connected with the primary hollow lead screw;

A secondary support frame is arranged on the secondary lead screw, two ends of the secondary planetary roller are respectively connected to the secondary support frame, the secondary planetary roller is threadedly connected to the secondary long nut, the secondary lead screw is threadedly connected to the secondary planetary roller, the secondary retaining ring is fixedly arranged on the outer wall of the secondary lead screw to fix the secondary support frame, the track of the second guide slide rail is arranged on the outer wall of the secondary lead screw, and the keyway of the first guide slide rail is arranged inside the front end cover of the primary hollow lead screw.

The shell is provided with radial holes for passing the wires.

The second frameless torque motor fixing piece is provided with radial holes for passing the wires.

Working process and working principle of the present invention:

The first frameless torque motor stator and the first frameless torque motor rotor constitute a first frameless torque motor; the second frameless torque motor stator and the second frameless torque motor rotor constitute a second frameless torque motor.

The first annular magnetic encoder stator and the first annular magnetic encoder rotor form a first annular magnetic encoder; the second annular magnetic encoder stator and the second annular magnetic encoder rotor form a second annular magnetic encoder.

During use of the present invention, the first frameless torque motor directly drives the first-stage long nut, and the rotational motion of the first-stage long nut is converted into the linear motion of the first-stage hollow lead screw through the first-stage planetary roller. The first guide rail limits the rotational freedom of the first-stage hollow lead screw to ensure the linearity of its movement. At the same time, the first annular magnetic encoder is used to feedback the angle, angular velocity and angular acceleration of the first frameless torque motor; the second frameless torque motor directly drives the solid part of the second-stage long nut, and the rotational motion of the second-stage long nut is converted into the linear motion of the second-stage lead screw through the second-stage planetary roller. The second guide rail limits the rotational freedom of the second-stage lead screw to ensure the linearity of its movement. The second annular magnetic encoder is used to feedback the angle, angular velocity and angular acceleration of the second frameless torque motor; When short-stroke work is required, only one frameless torque motor is needed. When quick response is required, the first frameless torque motor does not need to work, and the second frameless torque motor drives the secondary reverse planetary roller screw subassembly to move; when high load is required, the second frameless torque motor does not need to work, and the first frameless torque motor drives the primary reverse planetary roller screw subassembly to move; when long-stroke work is required, the first frameless torque motor and the second frameless torque motor work together to achieve two-stage synchronous motion or more complex motion forms; for special work requirements, the first frameless torque motor and the second frameless torque motor can cooperate with each other. Since the two stages can be controlled independently, the movement of the two stages can be customized, thereby completing work requirements that cannot be achieved by general two-stage electric cylinders.

Beneficial effects of the present invention:

(1) The present invention adopts a two-stage reverse planetary roller screw subassembly design, which can not only withstand higher loads, but also ensure high transmission efficiency, low heat generation and long service life. The two-stage modular design is easy to disassemble and maintain.

(2) The present invention adopts a frameless torque motor. Since there is no power transmission mechanism, direct transmission of driving force and efficient operation are ensured, and the axial and radial dimensions are reduced to the greatest extent, making the design more compact and easy to integrate.

(3) The present invention adopts two independent frameless torque motors to drive the two-stage long nuts respectively, and is equipped with two annular magnetic encoders to monitor the status of the motors in real time, thereby realizing precise control of the two-stage long nuts. This control method not only allows the two stages to move synchronously to meet the requirements of coordinated work, but also supports independent movement of the two stages. The movement of the two stages can be customized to cope with more complex special work scenarios.

(4) The present invention adopts two guide rails to ensure the linearity of the electric cylinder during movement, reduce friction and wear, and improve the smoothness of movement and service life.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a one-stage reverse planetary roller screw subassembly according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a two-stage reverse planetary roller screw subassembly according to an embodiment of the present invention.

In the figure:

1-cylinder body; 11-front end cover; 12-housing; 13-rear end cover; 2-first power assembly; 21-first frameless torque motor stator; 22-first frameless torque motor rotor; 23-first annular magnetic encoder stator; 24-first annular magnetic encoder rotor; 3-second power assembly; 31-second frameless torque motor stator; 32-second frameless torque motor rotor; 33-second annular magnetic encoder stator; 34-second annular magnetic encoder rotor; 4-bearing group; 41-first bearing; 42-second bearing; 43-third bearing; 44-fourth bearing ;5-first-stage reverse planetary roller screw subassembly;51-first-stage long nut;52-first-stage planetary roller;53-first-stage support frame;54-first-stage retaining ring;55-first-stage hollow screw;56-first-stage guide rail;57-first-stage hollow screw front end cover;58-second-frameless torque motor fixing piece;59-first-stage hollow screw rear end cover;6-second-stage reverse planetary roller screw subassembly;61-second-stage long nut;62-second-stage planetary roller;63-second-stage support frame;64-second-stage retaining ring;65-second-stage screw;66-second-stage guide rail.

DETAILED DESCRIPTION

Please refer to FIG. 1 to FIG. 3 , which are embodiments of the present invention.

A two-stage precision electric cylinder based on a reverse planetary roller screw comprises a cylinder body 1, a first power assembly 2, a second power assembly 3, a bearing group 4, a first-stage reverse planetary roller screw subassembly 5 and a second-stage reverse planetary roller screw subassembly 6;

The cylinder body 1 comprises a front end cover 11, a shell 12 and a rear end cover 13;

The first power assembly 2 comprises a first frameless torque motor stator 21, a first frameless torque motor rotor 22, a first annular magnetic encoder stator 23 and a first annular magnetic encoder rotor 24;

The second power assembly 3 comprises a second frameless torque motor stator 31, a second frameless torque motor rotor 32, a second annular magnetic encoder stator 33 and a second annular magnetic encoder rotor 34;

The bearing group 4 comprises a first bearing 41, a second bearing 42, a third bearing 43 and a fourth bearing 44;

The two-stage reverse planetary roller screw subassembly 6 comprises a two-stage long nut 61, a two-stage planetary roller 62, a two-stage support frame 63, a two-stage retaining ring 64, a two-stage screw 65 and a second guide rail 66;

The front cover 11 and the housing 12, and the rear cover 13 and the housing 12 are connected by screws, and flanges are provided at the connection between the front cover 11 and the housing 12 and at the connection between the rear cover 13 and the housing 12, so that the front cover 11, the rear cover 13 and the housing 12 are embedded and connected;

One end of the first frameless torque motor stator 21 abuts against the protrusion of the inner wall of the housing 12 and is fixed to the inner wall of the housing 12 by structural adhesive. One end of the first frameless torque motor rotor 22 abuts against the protrusion of the first-stage long nut 51 and is fixed to the outer wall of the first-stage long nut 51 by structural adhesive. The first annular magnetic encoder stator 23 is fixedly mounted on the inner wall of the rear end cover 13 by screws. The first annular magnetic encoder rotor 24 is fixedly connected to the first-stage long nut 51 by a set screw. The axis of the first annular magnetic encoder rotor 24 coincides with the axis of the first annular magnetic encoder stator 23.

One end of the second frameless torque motor stator 31 abuts against the protrusion of the inner wall of the second frameless torque motor fixing member 58, and is fixed to the inner wall of the second frameless torque motor fixing member 58 by structural glue, one end of the second frameless torque motor rotor 32 abuts against the protrusion of the solid part of the secondary long nut 61, and is fixedly connected to the outer wall of the solid part of the secondary long nut 61 by structural glue, the second annular magnetic encoder stator 33 is fixedly mounted on the inner wall of the rear end cover 59 of the primary hollow screw by screws, the second annular magnetic encoder rotor 34 is fixedly connected to the secondary long nut 61 by a set screw, and the axis of the second annular magnetic encoder rotor 34 coincides with the axis of the second annular magnetic encoder stator 33;

The outer wall of the first bearing 41 is matched and connected with the inner wall of part of the housing 12, the outer wall of the second bearing 42 is matched and connected with the inner wall of part of the rear end cover 13, the first bearing 41 and the second bearing 42 are symmetrically arranged at both ends of the first-stage long nut 51 for support and positioning, ensuring that the air gap between the first frameless torque motor stator 21 and the first frameless torque motor rotor 22 is uniform and the axial positions are correctly matched, the outer walls of the third bearing 43 and the fourth bearing 44 are matched and connected with the inner wall of part of the first-stage hollow screw 55, and the inner walls are symmetrically arranged at both ends of the second-stage long nut 61 for support and positioning, so that the air gap between the second frameless torque motor stator 31 and the second frameless torque motor rotor 32 is uniform and the axes coincide;

A primary support frame 53 is provided on the primary hollow lead screw 55, and both ends of the primary planetary roller 52 are respectively connected to the primary support frame 53, the primary planetary roller 52 is threadedly connected to the primary long nut 51, the primary hollow lead screw 55 is threadedly connected to the primary planetary roller 52, and the primary retaining ring 54 is fixedly arranged on the outer wall of the primary hollow lead screw 55 to fix the primary support frame 53. The track of the first guide slide rail 56 is arranged on the outer wall of the primary hollow lead screw 55, and the keyway of the first guide slide rail 56 is arranged inside the front end cover 11. The front end cover 57 of the primary hollow lead screw and the second frameless torque motor fixing piece 58 are connected to the primary hollow lead screw 55 by screws, and the rear end cover 59 of the primary hollow lead screw is connected to the second frameless torque motor fixing piece 58 by screws. The connection between the front end cover 57 of the primary hollow lead screw and the second frameless torque motor fixing piece 58 is provided with a flange, so that the front end cover 57 of the primary hollow lead screw and the second frameless torque motor fixing piece 58 are embedded and connected with the primary hollow lead screw 55;

A secondary support frame 63 is provided on the secondary lead screw 65, both ends of the secondary planetary roller 62 are respectively connected to the secondary support frame 63, the secondary planetary roller 62 is threadedly connected to the secondary long nut 61, the secondary lead screw 65 is threadedly connected to the secondary planetary roller 62, the secondary retaining ring 64 is fixedly set on the outer wall of the secondary lead screw 65 to fix the secondary support frame 63, the track of the second guide rail 66 is set on the outer wall of the secondary lead screw 65, and the keyway of the first guide rail 56 is set inside the front end cover 57 of the primary hollow lead screw.

The housing 12 is provided with radial holes for passing wires.

The second frameless torque motor fixing member 58 is provided with radial holes for passing the wires.

The working principle and working process of this embodiment: When this embodiment is in use, the first frameless torque motor directly drives the first-stage long nut 51, and converts the rotational motion of the first-stage long nut 51 into the linear motion of the first-stage hollow lead screw 55 through the first-stage planetary roller 52. The first guide rail 56 limits the rotational freedom of the first-stage hollow lead screw 55 to ensure the linearity of its movement. At the same time, the first annular magnetic encoder is used to feedback the angle, angular velocity and angular acceleration of the first frameless torque motor; the second frameless torque motor directly drives the solid part of the second-stage long nut 61, and converts the rotational motion of the second-stage long nut 61 into the linear motion of the second-stage lead screw 65 through the second-stage planetary roller 62. The second guide rail 66 limits the rotational freedom of the secondary lead screw 65 to ensure the linearity of its movement. The second annular magnetic encoder is used to feedback the angle of the second frameless torque motor , angular velocity and angular acceleration; when short-stroke work is required, only one frameless torque motor is needed. When quick response is required, the first frameless torque motor does not need to work, and the second frameless torque motor drives the secondary reverse planetary roller screw subassembly 6 to move; when high load is required, the second frameless torque motor does not need to work, and the first frameless torque motor drives the primary reverse planetary roller screw subassembly 5 to move; when long-stroke work is required, the first frameless torque motor and the second frameless torque motor work together to achieve two-stage synchronous motion or more complex motion forms; for special work requirements, the first frameless torque motor and the second frameless torque motor can cooperate with each other. Since the two stages can be controlled independently, the movement of the two stages can be customized, thereby completing work requirements that cannot be achieved by general two-stage electric cylinders.

Claims (3)

1. A secondary precision electric cylinder based on reverse planetary roller screw is characterized in that: the device comprises a cylinder body (1), a first power assembly (2), a second power assembly (3), a bearing group (4), a primary reverse planetary roller screw pair assembly (5) and a secondary reverse planetary roller screw pair assembly (6);

The cylinder body (1) comprises a front end cover (11), a shell (12) and a rear end cover (13);

The first power assembly (2) comprises a first frameless torque motor stator (21), a first frameless torque motor rotor (22), a first annular magnetic encoder stator (23) and a first annular magnetic encoder rotor (24);

the second power assembly (3) comprises a second frameless torque motor stator (31), a second frameless torque motor rotor (32), a second annular magnetic encoder stator (33) and a second annular magnetic encoder rotor (34);

The bearing group (4) comprises a first bearing (41), a second bearing (42), a third bearing (43) and a fourth bearing (44);

The secondary reverse planetary roller screw pair assembly (6) comprises a secondary long nut (61), a secondary planetary roller (62), a secondary support frame (63), a secondary retainer ring (64), a secondary screw (65) and a second guide slide rail (66);

The front end cover (11) is connected with the shell (12) and the rear end cover (13) is connected with the shell (12) through screws, and flanges are arranged at the joint of the front end cover (11) and the shell (12) and the joint of the rear end cover (13) and the shell (12), so that the front end cover (11) and the rear end cover (13) are connected with the shell (12) in an embedded mode;

One end of a first frameless torque motor stator (21) is abutted against the bulge of the inner wall of the shell (12) and fixed on the inner wall of the shell (12) through structural adhesive, one end of a first frameless torque motor rotor (22) is abutted against the bulge of a first-stage long nut (51) and fixed on the outer wall of the first-stage long nut (51) through structural adhesive, a first annular magnetic encoder stator (23) is fixedly arranged on the inner wall of a rear end cover (13) through screws, a first annular magnetic encoder rotor (24) is fixedly connected with the first-stage long nut (51) through a set screw, and the axes of the first annular magnetic encoder rotor (24) and the first annular magnetic encoder stator (23) are overlapped;

One end of a second frameless torque motor stator (31) is abutted against the bulge of the inner wall of a second frameless torque motor fixing piece (58) and is fixed on the inner wall of the second frameless torque motor fixing piece (58) through structural adhesive, one end of a second frameless torque motor rotor (32) is abutted against the bulge of the solid part of a second long nut (61) and is fixedly connected with the outer wall of the solid part of the second long nut (61) through structural adhesive, a second annular magnetic encoder stator (33) is fixedly arranged on the inner wall of a first-stage hollow screw rear end cover (59) through a screw, a second annular magnetic encoder rotor (34) is fixedly connected with the second long nut (61) through a set screw, and the second annular magnetic encoder rotor (34) is overlapped with the axis of the second annular magnetic encoder stator (33);

The outer wall of the first bearing (41) is connected with part of the inner wall of the shell (12) in a matched manner, the outer wall of the second bearing (42) is connected with part of the inner wall of the rear end cover (13) in a matched manner, the first bearing (41) and the second bearing (42) are symmetrically arranged at two ends of the first-stage long nut (51) to support and position, the air gap of the first rimless torque motor stator (21) and the air gap of the first rimless torque motor rotor (22) are ensured to be uniform and the axial position is correctly matched, the outer wall of the third bearing (43) and the outer wall of the fourth bearing (44) are connected with part of the inner wall of the first-stage hollow screw (55) in a matched manner, and the inner wall is symmetrically arranged at two ends of the second-stage long nut (61) to support and position, so that the air gap of the second rimless torque motor stator (31) and the second rimless torque motor rotor (32) are uniform and the axial position is coincident;

The one-stage hollow screw (55) is provided with a one-stage support frame (53), two ends of the one-stage planetary roller (52) are respectively connected to the one-stage support frame (53), the one-stage planetary roller (52) is in threaded connection with a one-stage long nut (51), the one-stage hollow screw (55) is in threaded connection with the one-stage planetary roller (52), a one-stage check ring (54) is fixedly arranged on the outer wall of the one-stage hollow screw (55), the one-stage support frame (53) is fixed, a track of a first guide slide rail (56) is arranged on the outer wall of the one-stage hollow screw (55), a key slot of the first guide slide rail (56) is arranged inside a front end cover (11), the one-stage hollow screw front end cover (57) and a second frameless torque motor fixing piece (58) are connected with the one-stage hollow screw (55) through screws, and flanges are respectively arranged at the connection positions of the one-stage hollow screw front end cover (57) and the second frameless torque motor fixing piece (58) so that the one-stage hollow screw front end cover (57) and the second frameless torque motor fixing piece (58) are connected with the one-stage hollow screw (55) through screws;

Be provided with second grade support frame (63) on second grade lead screw (65), the both ends of second grade planet roller (62) are connected respectively on second grade support frame (63), second grade planet roller (62) and second long nut (61) threaded connection, second grade lead screw (65) and second grade planet roller (62) threaded connection, second grade retaining ring (64) are fixed to be set up on the outer wall of second grade lead screw (65), fix second grade support frame (63), the track setting of second direction slide rail (66) is at second grade lead screw (65) outer wall, the keyway setting of first direction slide rail (56) is inside one-level hollow lead screw front end housing (57).

2. The secondary precision electric cylinder based on the reverse planetary roller screw as claimed in claim 1, wherein: the shell (12) is provided with a radial hole for the harness.

3. The secondary precision electric cylinder based on the reverse planetary roller screw as claimed in claim 1, wherein: the second frameless torque motor fixing piece (58) is provided with a radial hole for a through wire.