阅读说明：本技术 一种基于电涡流效应的无接触式随动辅助支承与减振装置 (Non-contact follow-up auxiliary supporting and vibration damping device based on eddy current effect ) 是由 张雪萍 张鑫 巴哈德尔 于 2021-08-26 设计创作，主要内容包括：本发明涉及一种基于电涡流效应的无接触式随动辅助支承与减振装置,包括线圈绕组、永磁铁组、上侧永磁铁壳体、下侧永磁铁壳体、铁芯、线性驱动电机组、支承座、铣刀和主轴外壳,待铣削的薄壁件位于上侧永磁铁壳体和下侧永磁铁壳体之间,上侧永磁铁壳体通过螺栓固定在主轴外壳上,下侧永磁铁壳体固定在支承座上,永磁铁组分别布置在上侧永磁铁壳体和下侧永磁铁壳体中,铣刀设于薄壁件和上侧永磁铁壳体之间,线性驱动电机组固定在支承座上,实时读取刀具三维坐标信息,通过上侧和下侧的永磁铁组控制铣刀的运动。与现有技术相比,本发明具有抑制薄壁件在铣削中的变形与颤振,克服复杂庞大的静态辅助支承阵列,提升加工质量及加工效率等优点。(The invention relates to a non-contact follow-up auxiliary supporting and vibration damping device based on an eddy current effect, which comprises a coil winding, a permanent magnet group, an upper permanent magnet shell, a lower permanent magnet shell, an iron core, a linear driving motor group, a supporting seat, a milling cutter and a spindle shell, wherein a thin-wall part to be milled is positioned between the upper permanent magnet shell and the lower permanent magnet shell, the upper permanent magnet shell is fixed on the spindle shell through bolts, the lower permanent magnet shell is fixed on the supporting seat, the permanent magnet group is respectively arranged in the upper permanent magnet shell and the lower permanent magnet shell, the milling cutter is arranged between the thin-wall part and the upper permanent magnet shell, the linear driving motor group is fixed on the supporting seat, the three-dimensional coordinate information of the cutting tool is read in real time, and the movement of the milling cutter is controlled through the upper permanent magnet group and the lower permanent magnet group. Compared with the prior art, the invention has the advantages of inhibiting the deformation and the flutter of the thin-wall part in the milling process, overcoming the complex and huge static auxiliary support array, improving the processing quality and the processing efficiency and the like.)

1. A non-contact follow-up auxiliary supporting and vibration damping device based on an eddy current effect is characterized by comprising a coil winding (6), a permanent magnet group, an upper permanent magnet shell (10), a lower permanent magnet shell (5), an iron core (7), a linear driving motor group, a supporting seat (2), a milling cutter (9) and a spindle shell (12), wherein the coil winding (6) is wound on the iron core (7), a thin-walled piece (8) to be milled is positioned between the upper permanent magnet shell (10) and the lower permanent magnet shell (5), the upper permanent magnet shell (10) is fixed on the spindle shell (12) through a bolt, the lower permanent magnet shell (5) is fixed on the supporting seat (2), the permanent magnet groups are respectively arranged in the upper permanent magnet shell (10) and the lower permanent magnet shell (5), and the milling cutter (9) is arranged between the thin-walled piece (8) and the upper permanent magnet shell (10), the linear driving motor set is fixed on the supporting seat (2), three-dimensional coordinate information of the cutter is read in real time, and the movement of the milling cutter (9) is controlled through the upper permanent magnet set and the lower permanent magnet set.

2. The non-contact follow-up auxiliary supporting and vibration damping device based on eddy current effect as claimed in claim 1, wherein the linear driving motor set comprises an X-direction linear motor, a Y-direction linear motor and a Z-direction linear motor.

3. The non-contact follow-up auxiliary supporting and damping device based on the eddy current effect is characterized in that the driving rod (1) of the X-direction linear motor and the driving rod (3) of the Y-direction linear motor are fixed on two side surfaces of the supporting seat (2) through bolts, the Z-direction linear motor is fixed on the top surface of the supporting seat (2) through bolts, and the driving rod (4) of the Z-direction linear motor is fixed on the lower permanent magnet shell (5) through bolts.

4. A non-contact follow-up auxiliary supporting and damping device based on the eddy current effect as claimed in claim 1, characterized in that the iron core (7) is made of silicon steel sheet (17) and comprises a central cylinder and a plurality of L-shaped branches located around the central cylinder, and the coil winding (6) is wound on the central cylinder.

5. The non-contact follow-up auxiliary supporting and damping device based on the eddy current effect is characterized in that the coil winding (6) and the iron core (7) form an electromagnetic supporting structure, sawtooth-shaped periodic variable current is introduced into the coil, and a variable magnetic field passing through the thin-wall part (8) is led out from the end face of the central cylinder and the L-shaped branch of the iron core through electromagnetic induction.

6. A non-contact follow-up support and vibration damping device based on eddy current effect according to claim 1, characterized in that the periphery of the upper permanent magnet shell (10) and the lower permanent magnet shell (5) is a closed ring groove structure of the same size, and the permanent magnet groups are arranged in the ring groove.

7. The non-contact follow-up auxiliary supporting and damping device based on the eddy current effect is characterized in that the number of the permanent magnet groups in the upper permanent magnet shell (10) and the lower permanent magnet shell (5) is the same, the permanent magnet groups are arranged in the annular groove according to a Halbach array to form an upper permanent magnet array (15) and a lower permanent magnet array (13), and the upper permanent magnet array (15) and the lower permanent magnet array (13) are distributed in a mirror symmetry mode about the middle thin-wall part (8) to form a permanent magnet damping structure.

8. The non-contact follow-up auxiliary supporting and damping device based on the eddy current effect is characterized in that the tail part of the upper permanent magnet shell (10) is a cylindrical shell, a threaded through hole is formed in the cylindrical shell, and a bolt is used for fixing the upper permanent magnet shell (10) on a spindle shell (12) which is wrapped with a rubber sleeve (11) through the threaded through hole.

9. A non-contact follow-up supporting and damping device based on eddy current effect as claimed in claim 1, characterized in that the bottom of the lower permanent magnet housing (5) is spoke-shaped, and the bottom of the iron core (7) is bonded to the center of the spoke-shaped of the lower permanent magnet housing (5).

10. The non-contact follow-up auxiliary supporting and damping device based on the eddy current effect as claimed in claim 1, characterized in that the upper permanent magnet shell (10) and the lower permanent magnet shell (5) are made of non-magnetic conductive or weakly magnetic conductive materials.

Technical Field

The invention relates to precision machining of large metal thin-wall parts in the industrial field, in particular to a thin-wall part non-contact auxiliary supporting and vibration damping device moving along with a cutter.

Background

The large metal thin-wall parts are widely applied to the industries of automobiles, ships, aerospace and the like, in particular to the aerospace industry. With the development of the aviation industry, the requirements on the dimensional accuracy and the surface quality of an integral thin-wall part are higher and higher, for example, the surface roughness requirement of a common large aluminum alloy sheet is less than 1 μm, and the dimensional accuracy requirement is less than 50 μm. However, due to the low rigidity characteristic of the thin-wall part, the thin-wall part is easy to deform and vibrate in milling, the processing quality of the thin-wall part is difficult to ensure, and for large-size complex curved surface thin-wall parts, the supporting system is large and complex, and the arrangement of the supporting units depends on experience, so that the processing efficiency is low; and long-time vibration has adverse effects on the health of operators and the service life of machine tools.

At present, the auxiliary supporting research of thin-wall parts is mainly static contact type rigid supporting, the design of the supporting device has complex structure, long production period and inconvenient installation, the determination of the supporting position depends on the experience of technicians, and the concrete reference is made in Chinese patent CN 102229058A; for large-sized thin-walled pieces, a support array system formed by a large number of auxiliary support units is large and complex, and before support, accurate characteristic information of the thin-walled pieces needs to be acquired, specifically refer to chinese patent CN203156615U) and CN 204546060U; because the static contact type supporting device is generally developed for a specific product, the production and design cost is high, the adaptability and the flexibility of the static contact type supporting device to different thin-wall parts are limited, and the flexibility requirement of the static contact type supporting device cannot be met. For a non-contact supporting research, a technical scheme that the rigidity of a thin-wall part can be improved by high-pressure gas or liquid is adopted, but the method often has the problems of leakage, poor controllability of supporting force and high energy consumption, and refer to chinese patent CN109277412A specifically, and it is necessary to ensure that the rigidity distribution heights of all parts of the thin-wall part are consistent, and refer to chinese patent CN111230527A specifically. For the research of the follow-up support, refer to chinese patent CN111299676A, which relates to transmission system, detection system and control system, the number of parts is large, the whole device has complex structure and is difficult to install; for the research on the suppression of the flutter in the thin-wall part machining, the vibration of the thin-wall part can be suppressed by suppressing the vibration of the thin-wall part support frame, specifically refer to chinese patent CN 105889380A; the scheme depends on a supporting frame matched with the appearance structure of the thin-wall part, and cannot be suitable for the vibration suppression of curved surface type or large-size thin-wall parts.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a non-contact follow-up auxiliary supporting and vibration damping device based on an eddy current effect, which can inhibit the deformation and the vibration of a thin-wall part in milling, overcome a complex and large static auxiliary supporting array, reduce the processing noise and improve the processing quality and the processing efficiency.

The purpose of the invention can be realized by the following technical scheme:

a non-contact follow-up auxiliary supporting and vibration damping device based on an eddy current effect comprises a coil winding, a permanent magnet group, an upper permanent magnet shell, a lower permanent magnet shell, an iron core, a linear driving motor group, a supporting seat, a milling cutter and a spindle shell, wherein the coil winding is wound on the iron core, a thin-wall part to be milled is located between the upper permanent magnet shell and the lower permanent magnet shell, the upper permanent magnet shell is fixed on the spindle shell through bolts, the lower permanent magnet shell is fixed on the supporting seat, the permanent magnet group is respectively arranged in the upper permanent magnet shell and the lower permanent magnet shell, the milling cutter is arranged between the thin-wall part and the upper permanent magnet shell, the linear driving motor group is fixed on the supporting seat, three-dimensional coordinate information of a cutter is read in real time, and the motion of the milling cutter is controlled through the upper permanent magnet group and the lower permanent magnet group.

The linear driving motor set comprises an X-direction linear motor, a Y-direction linear motor and a Z-direction linear motor.

Furthermore, the driving rod of the X-direction linear motor and the driving rod of the Y-direction linear motor are fixed on two side surfaces of the supporting seat through bolts, the Z-direction linear motor is fixed on the top surface of the supporting seat through bolts, the driving rod of the Z-direction linear motor is fixed on the lower permanent magnet shell through bolts, the X-direction linear motor and the Y-direction linear motor drive the supporting seat to move on the horizontal plane, the whole lower side device is kept to follow the cutter in the horizontal direction, and the Z-direction linear motor on the supporting seat drives the whole lower side device to move along with the cutter in the vertical direction.

The iron core is composed of silicon steel sheets and comprises a central cylinder and a plurality of L-shaped branches located around the central cylinder, a magnetic field is conveniently and effectively utilized and guided to one side of the thin-wall plate, and the coil winding is wound on the central cylinder and distributed between the five branches and the central cylinder.

Furthermore, the coil winding and the iron core form an electromagnetic supporting structure, sawtooth-shaped periodic variation current is introduced into the coil, and a variation magnetic field penetrating through the thin-wall part is led out from the end face of the central cylinder and the L-shaped branch of the iron core through electromagnetic induction.

The periphery of the upper permanent magnet shell and the periphery of the lower permanent magnet shell are of closed annular groove structures with the same size, and the permanent magnet groups are arranged in the annular grooves.

Furthermore, the number of the permanent magnet groups in the upper permanent magnet shell and the lower permanent magnet shell is the same, the permanent magnet groups are arranged in the annular groove according to the Halbach array and are fixed through the super glue to form a permanent magnet array, and the upper permanent magnet array and the lower permanent magnet array are distributed in mirror symmetry with respect to the middle thin-wall part to form a permanent magnet vibration damping structure.

The afterbody of upside permanent magnet casing is cylindric shell, has the screw thread through-hole on the cylindric shell, and the bolt passes through the screw thread through-hole to be fixed upside permanent magnet casing on the outer layer wraps up the main shaft shell that has the rubber sleeve, guarantees that upside permanent magnet casing and cutter relative position are fixed.

The bottom of the lower permanent magnet shell is of a spoke structure and used for reducing the weight, supporting the iron core and connecting a driving rod of the Z-direction linear motor, and the bottom of the iron core is bonded with the center of the spoke structure of the lower permanent magnet shell.

The upper permanent magnet shell and the lower permanent magnet shell are made of materials which are not magnetic conductive or have weak magnetic conductivity, so that the weight of the whole structure is reduced, and the magnetic field interference with the electromagnetic structure is reduced.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention is used as a technical scheme for inhibiting deformation and flutter and simplifying support in the milling of a large thin-wall part, integrates the following, suspension support and vibration reduction functions, improves the processing stability of the thin-wall part, and ensures the high-quality and high-efficiency milling of the thin-wall part.

2. The invention generates active eddy current effect in the thin-wall part through the electromagnetic structure, and forms continuous and stable suspension supporting force below the thin-wall part to balance milling force, wherein the size of the supporting force can be rapidly adjusted through setting of coil current parameters.

3. According to the invention, the Halbach permanent magnet vibration damping structure with mirror symmetry at the upper side and the lower side of the thin-wall part generates a strong magnetic field surrounding a processing area, and when the thin-wall part vibrates, strong electromagnetic damping is formed by utilizing an eddy current effect to realize effective inhibition of multi-order vibration modes of the thin-wall part.

4. The invention balances the milling heat source on the upper surface through the follow-up eddy current heat source on the lower surface of the thin-wall part, can inhibit the thermal deformation of the thin-wall part under the milling heat, and effectively improves the size precision of the milled workpiece.

5. The invention realizes the following of the electromagnetic supporting structure and the mirror permanent magnet vibration damping structure to the cutter by 3 sets of linear driving motors, thereby greatly simplifying the prior complex and huge static auxiliary supporting array system for processing large thin-walled parts.

6. According to the invention, the Halbach permanent magnet array mode and the specific silicon steel sheet iron core structure are adopted, the magnetic field is concentrated on the middle thin-wall part, the magnetic field of the coil and the permanent magnet array can be effectively utilized, and the suspension support avoids the surface of the workpiece from being scratched in the follow-up process.

Drawings

FIG. 1 is a simplified schematic diagram of the eddy current effect support and vibration suppression principles of the present invention;

FIG. 2 is a schematic view of the overall structure of the present invention;

FIG. 3 is a side view of the overall structure of the present invention;

FIG. 4 is a schematic diagram of the permanent magnet shell on the upper side of the thin-wall part and the Halbach permanent magnet array structure in the invention;

FIG. 5 is a schematic diagram of the electromagnetic structure, the permanent magnet housing and the Halbach permanent magnet array structure at the lower side of the thin-wall part in the invention;

FIG. 6 is a schematic structural view of the joint between the cutter and the spindle housing in the milling machine according to the present invention;

FIG. 7 is a general schematic diagram of a differential field coil winding configuration according to the present invention;

FIG. 8 is an overall schematic diagram of an excitation structure employing a rotating inner Halbach permanent magnet array in accordance with the present invention;

FIG. 9 is a schematic view of the thin-walled member lower inner and outer periphery permanent magnet array and rotating electric device structure according to the present invention shown in FIG. 8;

FIG. 10 is a schematic diagram of sawtooth-shaped periodic variation current in an embodiment of the present invention;

FIG. 11 is a schematic diagram of the magnetic field generated by the core in an embodiment of the present invention;

FIG. 12 is a schematic diagram of the measured ramp current in MATLAB at different times during 5 cycles in accordance with an embodiment of the present invention;

FIG. 13 is a graphical illustration of the vibration suppression effect of a Halbach array in an embodiment of the invention;

FIG. 14 is a diagram illustrating a frequency domain analysis result of the cantilever beam according to an embodiment of the present invention.

Reference numerals:

a 1-X direction linear motor driving rod; 2-a supporting seat; a 3-Y direction linear motor driving rod; a 4-Z direction linear motor; 5-lower permanent magnet housing; 6-a coil winding; 7-an iron core; 8-thin-walled parts; 9-milling cutter; 10-upper permanent magnet housing; 11-a rubber sleeve; 12-a spindle housing; 13-lower side permanent magnet array; 14-inner permanent magnet array; 15-upper side permanent magnet array; 16-milling cutter sleeve; 17-silicon steel sheet.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Examples

As shown in fig. 2 and 3, a non-contact follow-up auxiliary supporting and damping device based on eddy current effect comprises a coil winding 6, a permanent magnet set, an upper permanent magnet shell 10, a lower permanent magnet shell 5, an iron core 7, a linear driving motor set, a supporting seat 2, a milling cutter 9 and a spindle housing 12, wherein the coil winding 6 is wound on the iron core 7, a thin-wall part 8 to be milled is positioned between the upper permanent magnet shell 10 and the lower permanent magnet shell 5, the upper permanent magnet shell 10 is fixed on the spindle housing 12 through bolts, the lower permanent magnet shell 5 is fixed on the supporting seat 2, the permanent magnet set is respectively arranged in the upper permanent magnet shell 10 and the lower permanent magnet shell 5, the milling cutter 9 is arranged between the thin-wall part 8 and the upper permanent magnet shell 10, the linear driving motor set is fixed on the supporting seat 2, three-dimensional coordinate information of the cutter is read in real time, and the movement of the milling cutter 9 is controlled through the upper permanent magnet set and the lower permanent magnet set.

The linear driving motor group comprises an X-direction linear motor, a Y-direction linear motor and a Z-direction linear motor.

The driving rod 1 of the X-direction linear motor and the driving rod 3 of the Y-direction linear motor are fixed on two side surfaces of the supporting seat 2 through bolts, the Z-direction linear motor is fixed on the top surface of the supporting seat 2 through bolts, the driving rod 4 of the Z-direction linear motor is fixed on the lower permanent magnet shell 5 through bolts, the X-direction linear motor and the Y-direction linear motor drive the supporting seat 2 to move on the horizontal plane, the whole lower side device is kept to follow the cutter in the horizontal direction, and the Z-direction linear motor on the supporting seat 2 drives the whole lower side device to move along with the cutter in the vertical direction. As shown in fig. 6, the tool is connected to the spindle housing 12 by a milling cutter sleeve 16.

The iron core 7 is composed of silicon steel sheets 17, reduces eddy current loss and hysteresis loss, comprises a central cylinder and a plurality of L-shaped branches positioned around the central cylinder, ensures that the intensity of magnetic flux density is large enough and is concentrated on one side of the thin-wall part 8, so as to effectively utilize a magnetic field, and the coil winding 6 is wound on the central cylinder.

The coil winding 6 and the iron core 7 form an electromagnetic supporting structure, sawtooth-shaped periodic variable current is introduced into the coil, and a variable magnetic field penetrating through the thin-wall part 8 is led out from the end faces of the central cylinder and the L-shaped branch of the iron core through electromagnetic induction.

The peripheries of the upper permanent magnet shell 10 and the lower permanent magnet shell 5 are in a closed annular groove structure with the same size, and the permanent magnet groups are arranged in the annular grooves.

For the milling chattering problem of a large thin-wall part with low rigidity, in the embodiment, the vibration sources include: the cutting force changes periodically in the milling process and the sawtooth wave current changes suddenly. For the sudden change of the sawtooth wave current, because the change frequency of the current is far lower than the periodic change frequency of the milling force during high-speed milling, the suspension supporting force formed by ampere force is continuously stable relative to the milling force; on the other hand, the thin-walled part vibrates downwards due to sudden change of current, so that a magnetic field generated by the electromagnetic structure and penetrating through the thin-walled part 8 is enlarged, and the reason for enlarging the magnetic field is obstructed based on Lenz's law, namely the downward vibration of the thin-walled part 8 is restrained, and a vibration self-restraining effect is achieved. Therefore, the vibration caused by the abrupt change of the sawtooth wave current is negligible with respect to the vibration under the intermittent cutting force.

Aiming at the periodic variation of the milling force, as shown in fig. 4 and 5, the number of the permanent magnet groups in the upper permanent magnet shell 10 and the lower permanent magnet shell 5 is the same, and the permanent magnet groups are arranged in the annular groove according to the Halbach array to form an upper permanent magnet array 15 and a lower permanent magnet array 13, and the upper permanent magnet array 15 and the lower permanent magnet array 13 are distributed in a mirror symmetry manner relative to the middle thin-wall part 8 to form a permanent magnet vibration reduction structure and generate a strong magnetic field concentrated on one side of the thin-wall part 8; when the thin-wall part 8 vibrates in the horizontal direction or the vertical direction under the action of the periodic milling force, the thin-wall part 8, the upper permanent magnet array 15 and the lower permanent magnet array 13 move relatively to generate an eddy current effect, and the eddy current and the Halbach array strong magnetic field interact to form a damping force for blocking the thin-wall part to vibrate, namely an electromagnetic damper. The mirror symmetry distributed upper side permanent magnet array 15 and lower side permanent magnet array 13 play the effect of reinforcing its magnetic field horizontal component for thin wall spare 8 can more effectively cut the magnetic induction line and form great eddy current in the vibration, especially in the vibration of vertical direction and further strengthen permanent magnet array's damping effect. The magnetic field generated by the electromagnetic structure at the inner periphery of the lower permanent magnet array 13 can also generate an eddy current effect to inhibit the vibration of the thin-wall member 8 when the thin-wall member vibrates.

Except that the sawtooth wave current is used as an excitation source to form a stable eddy current on the lower surface of the thin-wall part, the permanent magnet array can be rotated to be used as the excitation source to form a stable and unchangeable eddy current on the lower surface of the thin-wall part, and the overall structure is shown in fig. 8. The coil winding 6 and the iron core 7 shown in figure 5 are replaced by the inner permanent magnet shell shown in figure 9 and the inner permanent magnet array 14 fixed in the shell and arranged in a Halbach mode, and the rest parts are kept consistent. The upper permanent magnet shell 5 is rotated through the rotating motor, then the inner permanent magnet array 14 is rotated to induce continuous and constant eddy current on the lower surface of the thin-walled part 8, and the eddy current and the horizontal component of the magnetic field of the inner permanent magnet array 14 act to form stable and constant ampere force balance milling force so as to inhibit the elastic deformation of the thin-walled part 8 during milling; the upper permanent magnet array 15 and the lower permanent magnet array 13 form electromagnetic damping, and an eddy current effect is generated in the vibration of the thin-wall part 8 to inhibit the vibration; similar to the electromagnetic structure, the inner permanent magnet array 14 provides the suspension supporting force, and the magnetic field thereof also plays a role in suppressing the vibration of the thin-walled member.

For high-speed milling during finish machining of the thin-wall part 8, particularly when the thickness of the thin-wall part is less than 8mm, a differential coil excitation structure shown in fig. 7 can be considered: the iron core 7 and the coil winding 6 which are formed by silicon steel sheets 17 are symmetrically arranged on the upper side and the lower side of the workpiece to form an electromagnetic structure which is mirror-symmetrical about the thin-wall part 8, and sawtooth wave current is simultaneously introduced into the upper coil and the lower coil. When the thin-wall part 8 is in a balance position, vertical magnetic field components induced by the coils at the two sides are mutually offset in the thin-wall part 8, no eddy current is generated in the thin-wall part 8, and the upper electromagnetic structure and the lower electromagnetic structure do not act on the thin-wall part 8; when the thin-wall part 8 is elastically deformed and flutters to deviate from a balance position under the action of milling force, a periodically and linearly increased net vertical magnetic field component passing through the thin-wall part 8 exists, so that a continuous eddy current is induced; the eddy current interacts with the strong horizontal magnetic field components of the upper mirror image electromagnetic structure and the lower mirror image electromagnetic structure to form ampere force, the effect of the ampere force always resists the reason of forming the eddy current, namely deformation and vibration, and the resisting effect is stronger and stronger along with the deviation of the thin-wall part from the balance position; the magnetic field of the upper and lower electromagnetic structures of the differential device forms an electromagnetic damping in the vibration of the thin-wall part 8 to inhibit the vibration. The differential electromagnetic structure limits the thin-walled piece 8 in an equilibrium position, so that milling can be performed stably; further, the rigidity of the thin-walled member 8 can be enhanced by enhancing the eddy current effect by increasing the magnitude of the current in the coil or the frequency of the current.

The afterbody of upside permanent magnet casing 10 is cylindric shell, has the screw thread through-hole on the cylindric shell, and the bolt passes through the screw thread through-hole to fix upside permanent magnet casing 10 on the spindle housing 12 that the outer parcel has rubber sleeve 11, and rubber sleeve 11 closely cup joints the surface at spindle housing 12, plays the effect of protection spindle housing.

The bottom of the lower permanent magnet shell 5 is in a spoke structure, and the bottom of the iron core 7 is bonded with the center of the spoke structure of the lower permanent magnet shell 5.

The upper permanent magnet case 10 and the lower permanent magnet case 5 are made of a material having no magnetic permeability or weak magnetic permeability.

In the embodiment, as shown in fig. 1, since the milling is essentially an interrupted cutting, the thin-walled member 8 is elastically deformed under the milling force and continuously vibrates during the milling. Through introducing sawtooth wave current to the coil winding 6, a periodic linear increasing magnetic field passing through the thin-wall part 8 is generated according to electromagnetic induction and the magnetic conduction effect of the iron core 7 with the branch-shaped structure, and continuous eddy current is formed on the lower surface of the thin-wall part 8 according to the Faraday's law of electromagnetic induction and the skin effect of eddy current; the eddy current and the horizontal component of the magnetic field generated by the electromagnetic structure act to form a stable upward ampere force to suspend and support the thin-wall part, balance the milling force and inhibit the elastic deformation of the thin-wall part 8 under the milling force. Because the ampere force is related to the eddy current, and the eddy current depends on the change speed of the vertical magnetic field component of the electromagnetic structure, the suspension supporting force can be quickly changed by adjusting the frequency parameter of the sawtooth wave current so as to meet the supporting force requirement under different milling forces, and the deformation of the thin-wall part 8 under different working conditions is inhibited.

In the embodiment, the three non-contact auxiliary supporting and damping devices are all based on the eddy current effect, wherein the first sawtooth wave current excitation type and the second rotating permanent magnet excitation type are suitable for the condition of large milling force, and the third differential excitation coil type is suitable for the condition of small milling force. The three devices can construct continuous and stable suspension supporting force so as to balance the milling force and inhibit the milling deformation of the thin-wall part 8; the suppression of 8 multi-order vibration modes of the thin-wall part can be realized; all with a dynamic following function to simplify the complex support array system of the large thin-walled member 8. For the eddy current heat source on the lower surface of the thin-wall part 8 in the embodiment, the heat source can move along with the cutter in the milling process, so that the lower surface of the thin-wall part 8 cannot be overheated; on the contrary, the continuous eddy current moving heat source on the lower surface of the thin-wall part 8 can balance the milling heat on the upper surface, inhibit the thermal deformation of the thin-wall part 8 under the milling heat and improve the dimensional accuracy of the thin-wall part 8.

In specific implementation, taking an aluminum alloy 1060 plate with the thickness delta of 10mm as an example, the radius R of the iron core of the lower electromagnetic structure silicon steel material is 25mm, the height L of the coil winding center cylinder is 20mm, the number n of turns of the coil in unit length is 1000/m, the iron core is made of a silicon steel sheet material, and the relative permeability mu is_rThe value is 5000, the magnitude of sawtooth wave current I led into the coil is 10A, the change period T is 0.1s, and the change slope k is 2, as shown in figure 10.

The formula of the equivalent current I' passing through the surface infinitesimal height dz of the iron core 7 is as follows:

I'＝nIdz

wherein n is the number of turns per unit length of the coil, and I is the current passing through the iron core 7; current elementThe magnetic field generated at any point P in space is according to biot-savart law:

wherein, mu₀Is the relative permeability of the iron core 7,is the vector of the infinitesimal current, r is the displacement of the infinitesimal current to P. Since the magnetic field formed by the coil is distributed symmetrically about the x-axis and the y-axis, only the yoz plane is studied in this exampleThe magnetic field on the surface is assumed to have coordinates of P (0, y, z) and the infinitesimal current (Rcos (α), Rsin (α), z)₀) Then, thenIs (-Rsin (alpha), Rcos (alpha), 0), wherein alpha is an included angle between the infinitesimal current and the x-axis, and the displacement from the infinitesimal current to P is r:

using vector multiplication to obtain magnetic induction intensityThe components in the y-axis and z-axis are as follows:

wherein θ isAndthe integral of the included angle between the iron core 7 in the axial direction and the radial direction is as follows:

according to the law of electromagnetic induction, when the current I shown in FIG. 10 is 10A, the period T is 0.1s sawtoothRadius r in thin-walled member 8 above core 7 when wave current flows₁Induces an induced electromotive force epsilon in the circular area_emf：

Wherein t is time.

Suppose that the induced electromotive force epsilon_emfThe eddy current formed at the bottom flows on a infinitesimal circular arc with the thickness dr₁The depth of penetration involved in the eddy current skin effect is Δ_hThen, the total resistance of the infinitesimal arc is:

wherein rho is the resistivity of the selected material aluminum alloy, and the induced current i is as follows:

the ampere force that an eddy current experiences in a magnetic field according to ampere's law is:

dF＝i·B_y·L＝i·B_y·2πr₁

the effective radius of the iron core 7 for leading out the magnetic field to pass through the thin-wall part is assumed to be r_cmThen the total ampere force experienced is:

because the partial integration exceeds the numerical calculation range and the total ampere force cannot be obtained through direct integration, the total ampere force F is calculated by a infinitesimal summation method in MATLAB software, as shown in FIG. 12, and is 316-320N. The slight fluctuation of 1.25% occurring in the ampere force is due to the fact that the sawtooth current rises linearly in one cycle, and since the fluctuation range is small, it is considered that the supporting effect is continuously stable.

Because the core material in this embodiment is a branched annular core, the magnetic field generated by the electromagnetic induction of the coil is directed to the thin-walled member 8, and the total ampere force is only the central cylindrical portion of the core 7; when no loss occurs in the magnetic flux density magnetic conduction process, the total ampere force generated by the five branch parts at the periphery of the iron core 7 in the thin-wall part 8 is equal to that of the central cylindrical part, so that the total branch force F formed by the whole electromagnetic device_supComprises the following steps:

F_sup＝2F＝630N

in the above, when the sawtooth wave current period is set to 0.1s, the support force is obtained, and when the milling force is changed due to the change of the milling parameter, the milling force can be balanced by adjusting the sawtooth wave current period to generate different suspension support forces.

The thin-wall part 8 can cut a stable magnetic field formed by the permanent magnet array in milling vibration, eddy current can be induced in the thin-wall part 8 based on an eddy current effect to resist vibration, and the formed damping force is as follows:

wherein the content of the first and second substances,is a magnetic field formed by a permanent magnet,the calculation formula of the eddy current density inside the magnetic induction line for the thin-wall part 8 vibration cutting permanent magnet array is as follows:

wherein sigma is the conductivity of the thin-wall part material,in order to pass the magnetic field of the thin-walled part 8,is the speed of the thin-walled member 8.

In the embodiment, only the main vibration inhibition condition of the Halbach permanent magnet array to the vertical direction of the thin-wall part is analyzed, and the speed of the thin-wall part 8 passing through the balance position is the maximum when milling vibration occurs and is recorded as v_zNeglecting the skin effect of the eddy current in the vibration of the thin-wall part 8, namely, the penetration depth of the eddy current is the thickness delta of the thin-wall part, and obtaining the electromagnetic damping force in the Z direction of the vibration of the thin-wall part 8 through the balance position as follows:

wherein r is_cFor a single permanent magnet to induce an equivalent radius of the eddy current on the thin-walled part 8, the damping coefficient c given by the single permanent magnet when the thin-walled part vibrates_eComprises the following steps:

for a single permanent magnet, assume its radius r_m17mm, thickness L of the permanent magnet of 15mm, remanence B of the permanent magnet_r1.476T, based on the Biot-savart law, the magnetic field of the permanent magnet in the y direction is obtained

Calculating to obtain the damping coefficient c of a single permanent magnet in MATLAB by utilizing a infinitesimal summation method_eIs 20.

Because the Halbach permanent magnet array is adopted in the embodiment, the magnetic field is concentrated on one side of the thin-wall part, and the actual y-direction magnetic field is larger than that of the thin-wall partAssuming that the magnetic induction intensity enhancement coefficient lambda is 1.5; in addition, the effective number m of the permanent magnet arrays in the embodiment is 4, and the Halbach permanent magnet arrays are arranged on the upper mirror image of the thin-wall part 8, so that the total damping coefficient is obtained as follows:

C_e＝2λ²mc_e＝360

when the speed v of the thin-walled member 8 at which the vibration passes through the equilibrium position is 0.5m/s, the electromagnetic damping force F given by the upper permanent magnet array 15 and the lower permanent magnet array 13 is generated_eComprises the following steps:

F_e＝C_ev＝180N

indicating that the faster the thin-walled member 8 vibrates, the greater the damping force exerted by the permanent magnet array.

The vibration suppression effect of the Halbach array is calculated based on COMSOL simulation, and frequency domain analysis is performed by taking a cantilever beam of an aluminum alloy material as an example to perform simulation, and the simulation is specifically shown in FIG. 13. From the simulated magnetic field distribution, the Halbach array concentrates the magnetic field on one side of the cantilever beam, so that the magnetic field is effectively utilized to inhibit the vibration of the cantilever beam. The results of the frequency domain analysis of the cantilever beam are shown in FIG. 14 for different permanent magnet arrangements.

From the results of the frequency domain simulation analysis in fig. 14, it is seen that the magnetic field of the permanent magnet can actually play a role in electromagnetic damping in the cantilever beam vibration, and the electromagnetic damping effects of different permanent magnet arrangement forms are greatly different; after the permanent magnet is changed into a Halbach permanent magnet array from a permanent magnet, the vibration suppression effect of the cantilever beam is very obvious, and further, after the Halbach array is arranged on the upper side and the lower side of the free vibration end of the cantilever beam in a mirror image mode, the cantilever beam is firmly limited at a balance position; compared with free vibration of a cantilever beam, the Halbach array arranged in a mirror image mode has the vibration suppression effect of more than 95%, and therefore the Halbach array arranged in a mirror image mode can form strong electromagnetic damping in vibration of a metal workpiece to effectively suppress vibration of the metal workpiece.

In addition, it should be noted that the specific embodiments described in the present specification may have different names, and the above descriptions in the present specification are only illustrations of the structures of the present invention. All equivalent or simple changes in the structure, characteristics and principles of the invention are included in the protection scope of the invention. Various modifications or additions may be made to the described embodiments or methods may be similarly employed by those skilled in the art without departing from the scope of the invention as defined in the appending claims.