A Magnetorheological Vibration Suppression Device and Method for Thin-Walled Workpieces

Abstract

The present invention discloses a magnetorheological vibration suppression device and method for thin-walled workpieces. The thin-walled workpiece is clamped tightly by a pressing block and fixed with bolts. At the same time, the thin wall is clamped by a flange nut to restrict its freedom of movement in the vertical direction. Before the planing process, the maximum deformation point of the thin sheet is analyzed by finite element simulation. Before processing, the magnetorheological fluid is sprayed on the surface of the thin-walled workpiece by a magnetorheological fluid sprayer, and the amount of magnetorheological fluid is appropriately increased at the locations with larger analyzed deformation amounts. During the cutting process, a displacement sensor is used to detect the deformation amount in the maximum deformation area on one side of the thin wall. The current in the magnetic field coil is adjusted by measuring the deformation amount of the thin sheet during the cutting process of the thin wall to adjust the magnetic field strength, change the damping of the magnetorheological fluid, reduce or offset the cutting force, and the vibration of the workpiece will be suppressed to a certain extent. A displacement sensor is used to measure the workpiece machining displacement responses before and after the application of the magnetic field respectively to analyze the vibration suppression effect of the sound wave.

Description

Technical Field

[0001] The present invention relates to the technical field of workpiece processing, and particularly to a magnetorheological vibration suppression device and method for thin-walled workpieces. Background Art

[0002] During the processing of thin-walled parts, machining vibration often occurs. The occurrence of machining vibration will reduce the surface quality of the workpiece and affect the machining efficiency, severely restricting the improvement of the machining quality and machining efficiency of the parts.

[0003] The existing machining vibration suppression methods mainly include the following: active dampers suppress machining vibration, passive dampers suppress machining vibration, and adjusting machining process parameters suppresses machining vibration. The application of both active and passive dampers requires connecting the damper to the workpiece surface, making the structure of the fixture more complex. For thin-walled workpieces, the rigidity of the workpiece is poor, and adjusting the machining process parameters cannot completely solve the machining vibration problem. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems mentioned in the background art. The present invention proposes a method in which a uniform magnetic field is provided by a coil magnetic field generator and an appropriate amount of magnetorheological fluid is sprayed on the surface of the thin-walled workpiece. When the coil is energized to generate a uniform magnetic field, the magnetic particles in the magnetorheological fluid form a chain-like structure under the action of the magnetic field; as the applied magnetic field strength increases, the chain-like structure further fuses to provide damping, thereby reducing the response displacement of the machined workpiece and suppressing machining vibration.

[0005] To achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A magnetorheological vibration suppression device for thin-walled workpieces, which includes a magnetic field generator, a thin-walled workpiece, a planer tool, and a laser displacement sensor. The thin-walled workpiece is fixed on a clamping device. The planer tool processes the end face of the upper end of the thin sheet and generates cutting vibration. The displacement situation is detected by a displacement sensor at the place with the largest deformation through finite element analysis, and the relationship between the displacement amount and the damping strength of the magnetorheological fluid under the magnetic field strength is solved to obtain a suitable magnetic field strength, and the current of the magnetic field generator is regulated to adjust the magnetic field strength to obtain a suitable damping to suppress machining vibration.

[0007] To optimize the above technical solution, the specific measures taken also include:

[0008] The number of the above-mentioned magnetic field generators is two. The magnetic field generators are linear magnetic field generators formed by winding circular coils. According to the Biot-Savart law, considering the characteristics of the external magnetic field environment required by the magnetorheological damper, which has a relatively large usable volume and a relatively high magnetic field uniformity, a circular coil type magnetic field generator is designed. In order to generate a relatively uniform magnetic field intensity at the central position of the magnetic field generator, two identical coils are wound and distributed on both sides of the thin-walled workpiece; the uniform magnetic field intensity can be controlled by controlling the current intensity input to the coils. In order to improve the working effect of the magnetorheological damper, while controlling the current to change the magnetic field intensity, the magnetic field generators on both sides can also be moved to make a parallel relative movement, and the damping effect is improved by using the extrusion mode and the shear mode at the same time.

[0009] During the clamping process of the thin-walled workpiece, without causing plastic deformation of the thin-walled workpiece, a relatively large pre-tightening force can be applied as much as possible to improve the stiffness of the workpiece, but resonance with the planer tool should be avoided.

[0010] The above-mentioned thin-walled workpiece is fixed by a pressing block and a locking bolt.

[0011] The method for suppressing the magnetorheological vibration during the machining of the thin-walled workpiece includes the following steps:

[0012] Step 1: The thin-walled workpiece is fixed on the fixed part by bolts and clamped by the flange nut and the bearing end cover in the movable clamping part. The pre-tightening force applied to the thin-walled workpiece is controlled by a torque wrench to improve the stiffness of the thin-walled workpiece;

[0013] Step 2: Design the machining process parameters of the thin-walled workpiece through orthogonal experiments and install a laser displacement sensor;

[0014] Step 3: Arrange the magnetic field generators, which are formed by winding two identical coils and distributed on both sides of the thin-walled workpiece.

[0015] Step 4: Before the planing machining, perform a finite element simulation analysis on the maximum deformation part of the thin-walled workpiece. Before machining, spray magnetorheological fluid on the surface of the thin-walled workpiece and appropriately increase the amount of magnetorheological fluid at the places with larger analyzed deformation amounts;

[0016] Step 5: Energize the magnetic field generators and machine the upper end face of the thin-walled workpiece with a planer tool; use a laser displacement sensor to detect, analyze and adjust the magnetic field generators to obtain a suitable current to control the magnetic field intensity, control the damping of the magnetorheological fluid, and suppress the vibration of the workpiece.

[0017] Step 6: Use a displacement sensor to measure the machining displacement responses of the thin-walled workpiece before and after applying the uniform magnetic field respectively, compare the two, and analyze the magnetorheological vibration effect.

[0018] In Step 2, before planing, the theoretical maximum vibration deformation area is obtained through finite element analysis, and the laser displacement sensor is installed in the area with the largest vibration deformation of the thin-walled workpiece.

[0019] The present invention has the following advantages:

[0020] The present invention has the following characteristics:

[0021] 1. Two angular contact balls are installed inside the movable clamping component of the clamping device to ensure that the friction between the thin sheet on the contact surface is changed from sliding friction to rolling friction, making the force state of the thin sheet simpler.

[0022] 2. The magnetorheological vibration suppression method has a simpler fixture structure than the traditional contact vibration suppression method. The magnetorheological fluid has different viscosity coefficients and has low environmental requirements, and can be mixed with impurities without affecting its stability.

[0023] 3. Since the installation position of the magnetic field generator and the distance from the workpiece will affect the transmission effect of the magnetic field, the installation position and distance should be determined according to the corresponding strength of the displacement of the workpiece.

[0024] 4. The present invention can control the input current value according to the vibration displacement measured by the laser displacement sensor to control the magnetic field strength to change within a certain range. At the same time, the magnetic field generators on both sides can be moved parallelly, and the extrusion mode and shear mode are used simultaneously to increase the damping force of the magnetorheological fluid. Description of the Drawings

[0025] Figure 1 is the flow chart of the magnetorheological vibration suppression method of the present invention;

[0026] Figure 2 is the layout diagram of the magnetorheological vibration suppression of the thin-walled workpiece of the present invention;

[0027] Figure 3 is the structural diagram of the movable clamping component of the present invention;

[0028] Figure 4 is the schematic diagram of the magnetic field distribution of the present invention;

[0029] Figure 5 is the schematic diagram of the magnetic field generator principle;

[0030] Names of the marks in the figure: magnetic field generator 1, externally applied pre-tightening force fixing component 2, fixing component 3, movable clamping component 4, thin-walled workpiece 5, magnetorheological fluid sprayer 6, planer tool 7, laser displacement sensor 8, flange nut 9, bearing end cover 10, screw one 11, thrust bearing 12, bushing 13, housing 14, screw two 15. Detailed Embodiments

[0031] The following further describes the embodiments of the present invention in detail with reference to the drawings.

[0032] Combined with Figure 1 and Figure 2 , the present invention relates to a method for suppressing vibration based on magnetorheological effect. In the following detailed description, many specific details of the present disclosure are illustrated by examples in order to provide a thorough understanding of the relevant disclosure.

[0033] Combined with Figure 1 , according to the cutting test settings, the thin-walled copper workpiece is fixed on the fixed part by bolts and clamped by the flange nut and bearing end cover in the movable clamping part. The thin-walled workpiece is fixed by applying torque to the pre-tightening force fixing part. The upper end face of the workpiece is machined by the planer tool 6, and the laser displacement sensor 7 is installed at a certain distance from the back of the workpiece.

[0034] The magnitude of the external pre-tightening force applied to the thin-walled workpiece by the pre-tightening force fixing part is controlled by inputting the torque magnitude through a torque wrench. It should be noted that when increasing the stiffness of the thin-walled workpiece, the free vibration frequency of the thin-walled workpiece changes under the applied pre-tightening force, and it must be avoided from the vibration frequency of the planer tool to prevent resonance.

[0035] The processing process parameters of the copper thin-walled parts are designed through orthogonal experiments, and the vibration displacement prediction model is obtained through finite element analysis.

[0036] Before planing, the forced vibration of the thin-walled workpiece is analyzed by finite element method to determine the amplitude of different regions of the workpiece. On this basis, the spraying amount and distribution of the magnetorheological fluid on the surface of the thin-walled workpiece are determined, and the magnetorheological fluid is symmetrically sprayed on both sides of the thin-walled workpiece. At the same time, a magnetorheological fluid product with appropriate viscosity needs to be selected to ensure that the magnetorheological fluid has sufficient adsorption force before the magnetic field is applied.

[0037] After spraying the magnetorheological fluid, the magnetic field needs to be generated by energizing in time to avoid as much as possible the change of the distribution of the magnetorheological fluid on the thin-walled workpiece under the action of gravity.

[0038] According to the vibration displacement measured by the laser displacement sensor, the input current value can be controlled to change the magnetic field intensity within a certain range. At the same time, the magnetic field generators on both sides can be moved in parallel, and the extrusion mode and shear mode are used simultaneously to increase the damping force of the magnetorheological fluid.

[0039] Combined with Figure 5 , the position of the laser displacement sensor 7 is determined as follows: According to the theoretical model analysis, the theoretical maximum vibration deformation region is obtained through finite element analysis, and the laser displacement sensor is installed in the region with the largest vibration deformation of the thin-walled workpiece.

[0040] Such as Figure 5As shown in the figure, in order to determine the magnetic field direction at any point P on the circumference of the circular coil, two current elements I dl of the same magnitude are taken at both ends of any diameter AA' of the coil. It can be seen from the figure that: ∠OAP = ∠OA'P = α. According to the Biot-Savart law, the direction of the magnetic field dB at point P generated by the current element at A should be perpendicular to the plane formed by the current element at A and AP. Similarly, the direction of the magnetic field dB' at point P generated by the current element at A' is perpendicular to the plane formed by the current element at A' and A'P. Therefore, dB = dB', and the direction is to the right along the axis of the circular coil.

[0041] The entire circular coil is divided into countless pairs of current elements of equal magnitude and opposite directions at both ends of their respective diameters. Since the magnetic field directions of each pair of current elements at P are all upward along the axis, the direction of the total magnetic field B of the entire energized circular coil at P is also upward along the axis, satisfying Ampere's right-hand rule with the direction of the current flowing through the circular coil. Thus, the magnitude B of the total magnetic field at point P is the sum of the axial components dBcosα of the elemental magnetic fields of each current element at P, that is:

[0042] When point P is located at the center O of the circular coil, that is, x = 0; at this time, the magnitude of the magnetic field is: where μ0 is the magnetic permeability, I is the current, and R is the radius of the ring.

[0043] To verify the accuracy of the designed magnetic field generator, the axial Hall probe is vertically placed at the center position of the coil, and the gaussmeter reads the measured magnetic induction intensity, and the average value is taken after 5 groups of experimental measurements.

[0044] The above is only the preferred implementation mode of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A magnetorheological vibration suppression device for thin-walled workpieces, characterized in that: It includes a magnetic field generator (1), a thin-walled workpiece (5), a magnetorheological fluid sprayer (6), a planer tool (7), a laser displacement sensor (8), a fixed component (3), an externally applied pre-tightening force fixed component (2), and a movable clamping component (4). The thin-walled workpiece (5) is fixed to the fixed component (3) by bolts and is clamped by a flange nut and a bearing end cover in the movable clamping component (4). The movable height of the flange nut is adjustable. Two angular contact balls are installed in the movable clamping component (4) to ensure that the friction of the thin sheet on the contact surface changes from sliding friction to rolling friction, making the force state of the thin sheet simpler. Before planing, the magnetorheological fluid sprayer (6) sprays an appropriate amount of magnetorheological fluid on the thin-walled workpiece. The planer tool (7) processes the upper end surface of the thin-walled workpiece (5) and generates cutting vibration, causing deformation of the workpiece. The maximum amplitude position is obtained through finite element analysis, and the laser displacement sensor (8) is used to detect and analyze, and the magnetic field generator (1) is adjusted to obtain an appropriate current to control the magnetic field strength, control the damping of the magnetorheological fluid, reduce or offset the cutting force, and suppress the vibration of the workpiece.

2. The magnetorheological vibration suppression device for a thin-walled workpiece according to claim 1, wherein: Before planing, the vibration amplitude of different regions of the workpiece is determined through finite element software for planing vibration analysis. The laser displacement sensor (8) is aligned with the maximum deformation region of the thin-walled workpiece (5) for easy detection and amplitude analysis.

3. The magnetorheological vibration suppression device for a thin-walled workpiece according to claim 1, characterized in that: Before planing, the vibration amplitude of different regions of the workpiece is determined through finite element software for planing vibration analysis. On this basis, the spraying amount and distribution of the magnetorheological fluid on the surface of the thin-walled workpiece are determined, and symmetric spraying is carried out on both sides of the thin sheet workpiece.

4. A magnetorheological vibration suppression device for a thin-walled workpiece according to claim 1, characterized in that: The magnetic field generator (1) is a linear magnetic field generator formed by winding circular coils. In order to generate a relatively uniform magnetic field strength at the center position of the magnetic field generator, it is formed by winding two identical coils, which are distributed on both sides of the thin-walled workpiece. The uniform magnetic field strength can be controlled by controlling the current intensity input to the coils.

5. A magnetorheological vibration suppression device for a thin-walled workpiece according to claim 1, characterized in that: The thin-walled workpiece (5) is fixed to the fixed component (3) by bolts and a pressing block and is clamped by a flange nut and a bearing end cover in the movable clamping component (4). After restricting the degree of freedom of the thin-walled workpiece to move in the vertical direction, the externally applied pre-tightening force fixed component (2) can control the magnitude of the pre-tightening force applied to the thin-walled workpiece (5) through a torque wrench, which can avoid the resonance phenomenon between the planer tool (7) and the thin-walled workpiece (5).

6. The method for suppressing acoustic vibration in the machining of thin-walled workpieces by the device according to claim 1, characterized in that: It includes the following steps: Step 1: The thin-walled workpiece (5) is fixed to the fixed component (3) by bolts and is clamped by a flange nut and a bearing end cover in the movable clamping component (4). The externally applied pre-tightening force fixed component (2) controls the magnitude of the pre-tightening force applied to the thin-walled workpiece (5) through a torque wrench to improve the stiffness of the thin-walled workpiece (5); Step 2: The processing process parameters of the thin-walled workpiece (5) are designed through orthogonal experiments, and a laser displacement sensor is installed; Step 3: The magnetic field generator (1) is arranged and is formed by winding two identical coils, which are distributed on both sides of the thin-walled workpiece (5); Step 4: Before planing processing, finite element simulation analysis is carried out on the thin-walled workpiece (5) to find the maximum deformation position. Before processing, the magnetorheological fluid sprayer (6) sprays magnetorheological fluid on the surface of the thin sheet workpiece and appropriately increases the amount of magnetorheological fluid at the positions with larger analyzed deformation amounts; Step 5: Energize the magnetic field generator (1), and use the planer tool (7) to machine the upper end face of the thin-walled workpiece (5); use the laser displacement sensor (8) to detect, analyze and adjust the magnetic field generator (1) to obtain an appropriate current to control the magnetic field strength, control the damping of magnetorheology, and suppress the vibration of the workpiece. Step 6: Use the displacement sensor to measure the machining displacement responses of the thin-walled workpiece (2) before and after applying the uniform magnetic field respectively, compare the two, and analyze the vibration effect of magnetorheology.

7. The method for suppressing the vibration of a thin-walled workpiece by magnetorheological effect according to claim 6, characterized in that: In Step 1, the magnitude of the external pre-tightening force applied to the thin-walled workpiece (5) by the fixed component (5) is controlled by inputting the torque magnitude with a torque wrench to increase the stiffness of the thin-walled workpiece (5). It should be noted that the natural vibration frequency of the thin-walled workpiece changes under the applied pre-tightening force, and it must be avoided from the vibration frequency of the planer tool to prevent resonance.

8. The method for suppressing the vibration of a thin-walled workpiece by magnetorheological effect according to claim 6, characterized in that: In Step 2, the theoretical maximum vibration deformation region is obtained through finite element analysis before planing, and the laser displacement sensor is installed in the region with the largest vibration deformation of the thin-walled workpiece (5).

9. The method for suppressing the vibration of the thin-walled workpiece by magnetorheological effect according to claim 6, wherein: In Step 5, when adjusting the magnetic field generator (1) to obtain an appropriate current to control the magnetic field strength, it is necessary to ensure that the input current value is required to be as large as possible compared with the calculated and analyzed current to more effectively suppress the vibration of the workpiece.

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