Self-adaptive anti-centrifugal chuck based on magnetorheological elastomer

Abstract

The self-adaptive anti-centrifugal chuck comprises a chuck body and clamping jaws, T-shaped sliding blocks matched with T-shaped sliding grooves of the chuck body are machined on the bottom faces of the clamping jaws, threaded holes are formed in the clamping jaws, bearing frames are installed at the two ends of the T-shaped sliding grooves of the chuck body through bolts, and lead screws matched with the threaded holes are installed on the bearing frames through bearings. A notch is formed in one end of the lead screw and used for being driven by a hand or a tool to rotate, a magneto-rheological elastomer layer is arranged on the bottom face of the T-shaped sliding groove, and an embedding groove provided with an electromagnet is formed below the bottom of the chuck. A clamping force sensor is embedded in the clamping face of the clamping jaw, vibration sensors are evenly distributed on the upper surface of the chuck, a piezoelectric ceramic layer is arranged above or below the magnetorheological elastomer layer, the rigidity of the magnetorheological elastomer layer is adjusted through an electromagnet to compensate centrifugal force, the piezoelectric ceramic layer compensates vibration displacement, and the clamping force sensor feeds back clamping force in real time. And self-adaptive centrifugal and vibration interference resistant accurate clamping is achieved.

Description

Technical Field

[0001] This invention relates to the field of machining fixture technology, and in particular to a high-precision chuck that uses a magnetorheological elastomer material to respond to changes in the magnetic field, thereby adaptively adjusting the clamping force during high-speed rotation to resist the influence of centrifugal force and simultaneously suppress machining vibration. Background Technology

[0002] In high-precision machining, the chuck, as a core fixture, directly affects the workpiece machining accuracy due to its clamping stability. Traditional chucks (such as three-jaw and four-jaw chucks) rely on the mechanical clamping force of threaded drives or wedge mechanisms, performing well under low-speed, light-load conditions. However, when faced with high-speed rotation (≥5000rpm) or heavy-load workpieces (≥50kg), centrifugal force (F=mω²r, where m is the jaw / workpiece mass, ω is the angular velocity, and r is the radius of rotation) leads to two key problems: centrifugal force causes the jaws to shift radially outward, resulting in increased clearance in the threaded pair or loosening of the wedge mechanism, reducing clamping force and causing micro-displacement of the workpiece, ultimately leading to deviations in machining dimensions. During high-speed rotation, the natural frequency of the chuck and workpiece system may couple with the cutting force frequency, causing resonance, leading to deterioration of surface roughness and abnormal tool wear. Furthermore, for machining irregularly shaped workpieces, the chuck must be disassembled to replace the jaws, which is very inconvenient. Limitations of existing solutions: Mechanical locking improvement: Centrifugal expansion is compensated by adding radial locking screws or elastic washers, but it cannot dynamically respond to changes in rotational speed (locking force is fixed), and the washers are prone to plastic deformation under heavy load conditions; Hydraulic / pneumatic assisted: Relies on an external pressure source to maintain clamping force, but the pipeline pressure fluctuates greatly during high-speed rotation and cannot suppress vibration; Therefore, developing an intelligent chuck that can sense changes in centrifugal force in real time and actively adjust the clamping force while suppressing machining vibration is key to solving the problem of stability in high-precision machining. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects in the prior art and provide an adaptive anti-centrifugal chuck based on magnetorheological elastomers.

[0004] To achieve the above objectives, the technical solution of this invention is to design an adaptive anti-centrifugal chuck based on a magnetorheological elastomer, comprising a chuck and jaws. The chuck is bolted to a spindle. A conductive slip ring is provided on the side of the chuck away from the jaws. The conductive slip ring is fitted onto the spindle. The slip ring rotor of the conductive slip ring is bolted to the chuck. The slip ring stator of the conductive slip ring is bolted to a machine tool housing. The slip ring rotor is fitted onto the slip ring stator. The chuck has a disc-shaped structure with a through hole in the center. Multiple T-shaped grooves are evenly distributed along the circumference of the chuck end face. Each T-shaped groove extends radially along the chuck. The number of jaws is... The T-shaped slides correspond one-to-one, and the bottom surface of the chuck jaws is machined with T-shaped sliders that match the T-shaped slides. The top two sides are clamping surfaces. The chuck jaws have threaded holes along the direction of the T-shaped sliders. Bearing brackets are respectively provided at both ends of the T-shaped slides of the chuck. The bearing brackets are mounted on the chuck with bolts. A lead screw is mounted on the bearing bracket via bearings. The lead screw mates with the threaded holes. A groove is provided at the end of the lead screw away from the chuck axis. A magnetorheological elastomer layer is provided on the bottom surface of the T-shaped slides. An insert groove is provided below the T-shaped slides on the bottom of the chuck, and an electromagnet is installed in the insert groove. The electromagnet's wires are electrically connected to the controller through a conductive slip ring. A conductive slip ring is an electromechanical integrated electrical component used in electrical equipment to solve the problem of current transmission between two parts of a device rotating 360 degrees relative to each other. When two mechanical parts rotate continuously and without restriction at 360 degrees relative to each other, the wires need to be connected to the rotating parts, which can lead to wire entanglement. Therefore, a current connector (conductive slip ring) is needed to transmit power and signal current, solving the problem of cable entanglement caused by 360-degree rotation. All sensors and components on the chuck that require power and signal current transmission are connected to the terminals of the slip ring rotor. The power and signal currents are then transmitted to the controller via the slip ring stator, allowing the controller to electrically control the various components.

[0005] Furthermore, a clamping force sensor is embedded in the gripper surface, and the clamping force sensor is electrically connected to the controller via a conductive slip ring.

[0006] Furthermore, multiple vibration sensors are evenly distributed along the circumference of the upper surface edge of the chuck. A piezoelectric ceramic layer is disposed above or below the magnetorheological elastomer layer. The vibration sensors and the piezoelectric ceramic layer are electrically connected to the controller via conductive slip rings. The piezoelectric ceramic exhibits the inverse piezoelectric effect; when an electric field is applied to its ends, it undergoes mechanical deformation. The controller controls the direction and intensity of the electric field to cause the piezoelectric ceramic to deform in the opposite direction to the vibration or expansion force. If vibration in a certain direction is detected, the controller causes the piezoelectric ceramic to deform in the opposite direction, using the force generated by this deformation to counteract the vibration. The system employs a real-time monitoring and dynamic adjustment strategy. The sensors continuously collect system status information and feed it back to the controller in real time. Based on the latest feedback information, the controller adjusts the drive signal of the piezoelectric ceramic in real time to ensure that the generated reverse thrust is always opposite to the direction of the vibration or expansion force. Even when the vibration frequency, amplitude, or expansion force changes, the system can respond quickly and adjust the direction and magnitude of the reverse thrust in a timely manner to adapt to changes in operating conditions.

[0007] Furthermore, the jaw includes a jaw base and a replaceable jaw. The T-shaped groove is formed at the bottom of the jaw base, and the threaded hole is also formed on the jaw base. The replaceable jaw is installed above the jaw base by bolts, and the clamping surface is located on the replaceable jaw.

[0008] Furthermore, it also includes an adapter base located between the base claw and the replaceable claw. A first limiting groove is provided above the base claw, and a limiting block matching the first limiting groove is provided below the adapter base. The adapter base is bolted to the base claw. At least one set of square positioning keys is provided above the adapter base, and the square positioning keys are bolted to the adapter base. A second limiting groove matching the square positioning keys is provided below the replaceable claw, and the replaceable claw is bolted to the adapter base.

[0009] Furthermore, toothed positioning grooves are provided above the adapter base and below the replaceable claw.

[0010] Preferably, the magnetorheological elastomer layer is formed by vulcanizing a matrix rubber with carbonyl iron powder.

[0011] Furthermore, the piezoelectric ceramic layer is electrically connected to the overvoltage protection circuit.

[0012] Preferably, the clamping force sensor and vibration sensor are sensors equipped with wireless transmission.

[0013] In practical applications, when machining symmetrical workpieces such as cylinders, the force on each jaw is relatively uniform, and the on / off state and magnitude of the current in the electromagnet can be uniformly controlled based on feedback from sensors and rotation speed. For complex irregular workpieces, independent control is preferred, and the on / off state and magnitude of the current in the corresponding electromagnet position are controlled based on the data collected by the sensors at the corresponding jaws.

[0014] The advantages and beneficial effects of this invention are as follows: 1. By adjusting the magnetic field strength in the magnetorheological elastomer layer region using an electromagnet, the stiffness of the magnetorheological elastomer layer changes, dynamically compensating for the radial expansion caused by the centrifugal force generated by the high-speed rotation of the chuck, thus preventing workpiece loosening or machining deviation.

[0015] 2. The piezoelectric ceramic layer generates high-frequency active thrust under the control of the controller to compensate for the small vibration displacement of the chuck caused by cutting force or resonance. Combined with the vibration sensor to monitor the vibration frequency and amplitude in real time, vibration suppression is achieved.

[0016] 3. The clamping force sensor is embedded in the clamping surface of the jaws to provide real-time feedback on the actual clamping force. The controller dynamically optimizes the electromagnet current and the piezoelectric ceramic layer voltage based on the clamping force data to avoid over-clamping causing workpiece deformation or under-clamping causing loosening.

[0017] 4. The chuck adopts a combination structure of base chuck and replaceable chuck, and can quickly change chucks through the adapter base to adapt to workpieces of different shapes (such as cylinders and irregular parts) and improve versatility; the square positioning key and toothed positioning groove ensure the installation accuracy of the replaceable chuck. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the chuck of the present invention; Figure 2 This is a schematic diagram of the chuck structure of the present invention; Figure 3 This is an exploded view of the chuck of the present invention; Figure 4 This is a cross-sectional view of the chuck of the present invention; Figure 5 yes Figure 3 Detailed images; Figure 6 This is a schematic diagram of the structure of the chuck claw of the present invention.

[0019] In the diagram: 1. Chuck; 101. Through hole; 102. T-slot; 103. Insertion slot; 2. Jaw; 201. Clamping surface; 202. T-slide block; 203. Threaded hole; 21. Jaw base; 211. First limiting groove; 22. Replaceable jaw; 221. Second limiting groove; 23. Adapter base; 231. Limiting block; 232. Square positioning key; 233. Toothed positioning groove; 3. Bearing bracket; 301. Bearing; 4. Bolt; 5. Lead screw; 501. Groove; 6. Magnetorheological elastomer layer; 7. Electromagnet; 8. Clamping force sensor; 9. Vibration sensor; 10. Piezoelectric ceramic layer; 11. Spindle; 12. Conductive slip ring; 121. Slip ring rotor; 122. Slip ring stator; 13. Machine tool housing. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0021] according to Figures 1-4As shown, this invention is an adaptive anti-centrifugal chuck based on magnetorheological elastomers, including a chuck 1 and jaws 2. The chuck 1 is mounted on a spindle 11 through a through hole 101. A conductive slip ring 12 is provided on the side of the chuck 1 away from the jaws 2. The conductive slip ring 12 is fitted onto the spindle 11. The slip ring rotor 121 of the conductive slip ring 12 is mounted on the chuck 1 by bolts 4. The slip ring stator 122 of the conductive slip ring 12 is mounted on a machine tool housing 13 by bolts 4. The slip ring rotor 121 is fitted onto the slip ring stator 122. The chuck 1 has a disc-shaped structure with a through hole 101 in the center. Multiple T-shaped grooves 102 are evenly distributed along the circumference of the end face of the chuck 1. Each T-shaped groove 102 extends radially along the chuck 1. The number of jaws 2 corresponds one-to-one with the number of T-shaped grooves 102. The bottom surface of the chuck 2 is machined with a T-shaped slider 202 that matches the T-shaped slide groove 102, and the two sides of the top are clamping surfaces 201. The chuck 2 has a threaded hole 203 along the direction of the T-shaped slider 202. Bearing brackets 3 are respectively provided at both ends of the T-shaped slide groove 102 of the chuck 1. The bearing brackets 3 are installed on the chuck 1 by bolts 4. A lead screw 5 is installed on the bearing bracket 3 by bearings 301. The lead screw 5 cooperates with the threaded hole 203. A groove 501 is provided at the end of the lead screw 5 away from the axis of the chuck 1. A magnetorheological elastomer layer 6 is provided on the bottom surface of the T-shaped slide groove 102. An inlay groove 103 is provided below the T-shaped slide groove 102 at the bottom of the chuck 1. An electromagnet 7 is installed in the inlay groove 103. The wire of the electromagnet 7 is electrically connected to the controller through a conductive slip ring 12. The T-shaped groove 102 and the T-shaped slider 202 enable the jaw 2 to slide linearly along the radial direction of the chuck 1, ensuring that the jaw's movement direction strictly points towards / away from the center of the chuck 1. The magnetorheological elastomer layer 6 is formed by vulcanizing a mixture of matrix rubber and carbonyl iron powder. The magnetorheological elastomer layer 6 is located between the bottom surface of the T-shaped groove 102 and the bottom surface of the jaw 2, and its stiffness can be adjusted by the magnetic field strength generated by the electromagnet 7. During high-speed rotation, the electromagnet 7 is energized to generate a magnetic field, which increases the stiffness of the magnetorheological elastomer, thereby improving the contact stiffness or damping between the jaw 2 and the groove, effectively suppressing the radial displacement of the jaw 2 caused by centrifugal force, and ensuring clamping stability. One end of the lead screw 5 is provided with a slot 501, which is used to connect to a manual or tool-driven rotating lead screw 5, thereby moving the jaw 2.

[0022] A clamping force sensor 8 is embedded in the clamping surface 201 of the jaw 2. The clamping force sensor 8 is electrically connected to the controller via a conductive slip ring 12. The clamping force sensor 8, embedded in the clamping surface 201 of the jaw 2, monitors the actual clamping force of the jaws on the workpiece in real time and feeds the signal back to the controller. This is used to dynamically optimize the current of the electromagnet 7 and the voltage of the piezoelectric ceramic layer 10, ensuring that the clamping force remains stable within a safe range. The clamping force sensor 8 collects clamping force data from the contact surfaces of each jaw 2 with the workpiece in real time and transmits it to the controller. For symmetrical workpieces, the controller can uniformly adjust the current of the electromagnet 7 and the voltage of the piezoelectric ceramic layer; for irregularly shaped or irregular workpieces, independent control strategies can be implemented for different jaws 2, thereby achieving precise clamping force adjustment and avoiding local over-clamping or under-clamping.

[0023] Multiple vibration sensors 9 are evenly distributed along the circumference of the upper surface edge of the chuck 1. A piezoelectric ceramic layer 10 is disposed above or below the magnetorheological elastomer layer 6. The vibration sensors 9 and the piezoelectric ceramic layer 10 are electrically connected to the controller via a conductive slip ring 12. The vibration sensors 9 are mounted on the upper surface edge of the chuck 1 to detect the vibration frequency and amplitude of the chuck 1 and the workpiece system, and transmit the vibration data to the controller. The piezoelectric ceramic layer 10 is arranged above or below the magnetorheological elastomer layer 6. Based on the vibration frequency and amplitude signals collected in real time by the vibration sensors 9, the controller applies a corresponding high-frequency voltage to cause the piezoelectric ceramic to generate a small but rapid active displacement or force to counteract or suppress the vibration of the chuck 1 and the workpiece system. This combination of active control and passive damping can effectively reduce the vibration amplitude during processing and improve the surface finish.

[0024] according to Figure 5 As shown, the jaw 2 includes a jaw base 21 and a replaceable jaw 22. The T-shaped groove 102 is formed at the bottom of the jaw base 21, and the threaded hole 203 is also formed on the jaw base 21. The replaceable jaw 22 is mounted on the jaw base 21 by bolts 4, and the clamping surface 201 is located on the replaceable jaw 22.

[0025] according to Figure 5As shown, it also includes an adapter base 23, which is located between the chuck base 21 and the replaceable chuck 22. A first limiting groove 211 is provided above the chuck base 21, and a limiting block 231 matching the first limiting groove 211 is provided below the adapter base 23. The adapter base 23 is mounted on the chuck base 21 by bolts 4. At least one set of square positioning keys 232 is provided above the adapter base 23, and the square positioning keys 232 are mounted on the adapter base 23 by bolts 4. A second limiting groove 221 matching the square positioning keys 232 is provided below the replaceable chuck 22, and the replaceable chuck 22 is mounted on the adapter base 23 by bolts 4. The adapter base 23 is positioned by cooperating with the limiting block 231 of the jaw base 21 through the first limiting groove 211. The square positioning key 232 cooperates with the second limiting groove 221 of the replaceable jaw 22 to realize the quick installation and high-precision positioning of the replaceable jaw 22, adapting to workpieces of different shapes (such as cylinders and irregular parts) and improving the versatility of the chuck 1.

[0026] according to Figure 5 As shown, toothed positioning grooves 233 are provided on the upper part of the adapter base 23 and the lower part of the replaceable claw 22. The toothed positioning grooves 233 further increase the friction and positioning accuracy of the adapter base 23 and the replaceable claw 22, prevent the replaceable claw 22 from undergoing slight displacement during clamping, and ensure clamping stability.

[0027] The magnetorheological elastomer layer 6 is formed by vulcanizing a mixture of matrix rubber and carbonyl iron powder.

[0028] The piezoelectric ceramic layer 10 is electrically connected to the overvoltage protection circuit. The overvoltage protection circuit is integrated into the controller and is electrically connected to the piezoelectric ceramic layer 10. When the voltage of the piezoelectric ceramic layer 10 exceeds the threshold, the power supply is cut off to prevent the piezoelectric ceramic from being damaged by overvoltage breakdown and to ensure system safety.

[0029] The specific control process is as follows: Insert a tool into the slot 501 at one end of the lead screw 5, and drive the lead screw 5 to rotate manually or electrically, thereby moving the chuck 2 to clamp the workpiece. At this time, the clamping force sensor 8 transmits the initial clamping force value to the controller. Then, start the equipment, and the spindle 11 rotates, driving the slip ring rotor 121 of the conductive slip ring 12 and the entire chuck 1 to rotate. During the processing, the high rotation will generate centrifugal force, causing the chuck 2 to move radially away from the workpiece, resulting in a decrease in the clamping force between the chuck 2 and the workpiece. When the clamping force value transmitted by the clamping force sensor 8 to the controller is less than... Initially, the controller energizes the electromagnet 7, thereby generating a magnetic field around the magnetorheological elastomer layer 6, increasing the stiffness of the magnetorheological elastomer, thus improving the contact stiffness or damping between the jaw 2 and the slide, effectively suppressing the radial displacement of the jaw 2 caused by centrifugal force, and ensuring clamping stability. The magnitude of the current flowing through the electromagnet 7 changes continuously due to the real-time feedback value from the clamping force sensor 8, thereby dynamically controlling the clamping force between the jaw 2 and the workpiece within a suitable range, preventing the workpiece from loosening due to insufficient clamping force, and preventing the workpiece from being damaged due to excessive clamping force.

[0030] When the cutting tool contacts the workpiece, vibration is generated. At this time, the vibration sensor 9 on the chuck 1 transmits the vibration data to the controller. Based on the vibration frequency and amplitude signals collected in real time by the vibration sensor 9, the controller applies a corresponding high-frequency voltage, causing the piezoelectric ceramic to generate a small but rapid active displacement or force to counteract or suppress the vibration of the chuck 1 and workpiece system. This combination of active control and passive damping can effectively reduce the vibration amplitude during the machining process and improve the surface finish.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An adaptive anti-centrifugal chuck based on a magnetorheological elastomer, characterized in that, The system includes a chuck (1) and jaws (2). The chuck (1) is mounted on the spindle (11) by bolts (4). A conductive slip ring (12) is provided on the side of the chuck (1) away from the jaws (2). The conductive slip ring (12) is fitted onto the spindle (11). The slip ring rotor (121) of the conductive slip ring (12) is mounted on the chuck (1) by bolts (4). The slip ring stator (122) of the conductive slip ring (12) is mounted on the spindle (11) by bolts (4). Mounted on the machine tool housing (13), the slip ring rotor (121) is fitted onto the slip ring stator (122). The chuck (1) has a disc-shaped structure with a through hole (101) in the center. Multiple T-shaped grooves (102) are evenly distributed along the circumference of the end face of the chuck (1). Each T-shaped groove (102) extends radially along the chuck (1). The number of jaws (2) corresponds one-to-one with the number of T-shaped grooves (102). The bottom surface of the jaws (2) is machined with grooves corresponding to the T-shaped grooves (102). 102) A matching T-shaped slider (202) has clamping surfaces (201) on both sides of its top. The jaws (2) have threaded holes (203) along the direction of the T-shaped slider (202). Bearing brackets (3) are respectively provided at both ends of the T-shaped groove (102) of the chuck (1). The bearing brackets (3) are mounted on the chuck (1) by bolts (4). A lead screw (5) is mounted on the bearing brackets (3) by bearings (301). In conjunction with the threaded hole (203), the lead screw (5) is provided with a slot (501) at one end away from the axis of the chuck (1). A magnetorheological elastomer layer (6) is provided on the bottom surface of the T-shaped slide (102). An inlay groove (103) is provided below the T-shaped slide (102) at the bottom of the chuck (1). An electromagnet (7) is installed in the inlay groove (103). The wire of the electromagnet (7) is electrically connected to the controller through a conductive slip ring (12).

2. The adaptive anti-centrifugal chuck based on a magnetorheological elastomer according to claim 1, characterized in that, The clamping surface (201) of the jaw (2) is embedded with a clamping force sensor (8), which is electrically connected to the controller through a conductive slip ring (12).

3. The adaptive anti-centrifugal chuck based on magnetorheological elastomer according to claim 1, characterized in that, Multiple vibration sensors (9) are evenly distributed along the circumference of the upper surface edge of the chuck (1). A piezoelectric ceramic layer (10) is disposed above or below the magnetorheological elastomer layer (6). The vibration sensors (9) and the piezoelectric ceramic layer (10) are electrically connected to the controller through a conductive slip ring (12).

4. The adaptive anti-centrifugal chuck based on magnetorheological elastomer according to claim 1, characterized in that, The jaw (2) includes a jaw base (21) and a replaceable jaw (22). The T-shaped groove (102) is formed at the bottom of the jaw base (21), and the threaded hole (203) is also formed on the jaw base (21). The replaceable jaw (22) is mounted on the jaw base (21) by bolts (4), and the clamping surface (201) is located on the replaceable jaw (22).

5. The adaptive anti-centrifugal chuck based on a magnetorheological elastomer according to claim 4, characterized in that, It also includes an adapter base (23), which is located between the chuck base (21) and the replaceable chuck (22). A first limiting groove (211) is provided above the chuck base (21), and a limiting block (231) matching the first limiting groove (211) is provided below the adapter base (23). The adapter base (23) is installed on the chuck base (21) by bolts (4). At least one set of square positioning keys (232) is provided above the adapter base (23), and the square positioning keys (232) are installed on the adapter base (23) by bolts (4). A second limiting groove (221) matching the square positioning keys (232) is provided below the replaceable chuck (22), and the replaceable chuck (22) is installed on the adapter base (23) by bolts (4).

6. The adaptive anti-centrifugal chuck based on a magnetorheological elastomer according to claim 5, characterized in that, Toothed positioning grooves (233) are provided above the adapter base (23) and below the replaceable claw (22).

7. The adaptive anti-centrifugal chuck based on a magnetorheological elastomer according to claim 1, characterized in that, The magnetorheological elastomer layer (6) is formed by vulcanizing a mixture of matrix rubber and carbonyl iron powder.

8. The adaptive anti-centrifugal chuck based on a magnetorheological elastomer according to claim 3, characterized in that, The piezoelectric ceramic layer (10) is electrically connected to the overvoltage protection circuit.

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