Magnetic type point contact self-adaptive clamp for milling thin-wall workpiece

Abstract

The invention discloses a magnetic type point contact self-adaptive clamp for milling a thin-wall workpiece. The magnetic type point contact self-adaptive clamp comprises a driving side clamp and a driven side clamp, the driving side clamp comprises an integrated plate, a first aluminum connecting piece, a first magnetic ring and a plurality of ball type plungers, and a space formed by the integrated plate and a center hole of the first aluminum connecting piece is used for allowing a milling cutter to penetrate through; the driven side clamp comprises a circumferential clamping component and a center supporting component. The circumferential clamping part comprises a second aluminum connecting piece, a second magnetic ring, a coil and a coil shell; the central supporting part comprises a supporting head and a third magnetic ring; the driving side clamp is fixed on a main shaft of milling equipment; the driven side clamp is attracted to the opposite side of the driving side clamp through magnetic force. The clamp keeps synchronous with a milling cutter in the feeding process, and clamps a workpiece in real time so as to restrain vibration of the workpiece; and the telescopic balls are adopted to make contact with the workpieces, and the adaptability to the workpieces in different shapes is further improved. The clamp has the advantages of light weight, flexibility, high adaptability and the like.

Description

Technical Field

[0001] The present invention relates to vibration suppression and stability improvement during a workpiece machining process, and in particular to a process of milling variable thickness workpieces and curved surface workpieces using a hybrid robot. Background Art

[0002] As a typical thin-walled structure, aircraft skin plays a vital role in carrying and transmitting loads, ensuring the safety and stability of aircraft interior equipment. Selecting the appropriate skin material and optimizing the machining process and parameters can enhance overall aircraft performance and reduce maintenance costs. Typically, aircraft skin requires a balance between good aerodynamics and lightweight properties. Good aerodynamics ensures the aircraft can properly distribute loads, resulting in excellent maneuverability, while lightweight structures enhance the aircraft's endurance and payload capacity. In addition to thin walls and large dimensions, aircraft skin typically features variable thickness and curvature to achieve these properties. However, this optimized design increases the difficulty and complexity of aircraft skin machining, leading to significant material waste, difficulties in ensuring machining accuracy and efficiency, and potential damage to machining equipment. Specifically, the weak stiffness caused by thin walls frequently results in chatter during milling, resulting in rough machined surfaces and substandard material removal. The variable thickness and curved surfaces also place higher demands on the adaptability of auxiliary fixtures; simply supporting and holding thin workpieces is insufficient to meet the machining requirements of workpieces of varying shapes. Therefore, how to effectively assist clamping of workpieces with variable thickness and curved surfaces, adapt to workpieces of different shapes, and thus improve machining accuracy and efficiency, remains an important task. Summary of the Invention

[0003] In response to the above-mentioned prior art, the present invention provides a magnetic point-contact adaptive clamp for milling thin-walled workpieces, which effectively clamps thin-walled workpieces to improve their processing quality and efficiency. The clamp utilizes a concentric coil and magnet structure to provide real-time, adjustable support for the workpiece, thereby improving material removal rate and milling surface dimensional accuracy. Based on magnetic follow-up technology, it maintains synchronization with the milling cutter during the feed process, constantly clamping the workpiece to avoid significant deformation. The use of retractable balls for contact with the workpiece further enhances adaptability to workpieces of varying shapes. The clamp offers advantages such as lightweight, flexibility, real-time controllability, and strong adaptability.

[0004] In order to solve the above technical problems, the present invention proposes a magnetic point-contact adaptive fixture for milling thin-walled workpieces, comprising an active side fixture and a driven side fixture;

[0005] The active side fixture includes an integrated plate, which includes a center circular ring plate and three wing plates evenly distributed along the circumference of the center circular ring hole; a first aluminum connector with a center hole is fixed to one side of the integrated plate; a concentric positioning boss is provided on the outer side of the first aluminum connector; a first magnetic ring is fixed on the outer rotating surface of the concentric positioning boss; the end face of the concentric positioning boss is provided with N circumferentially evenly distributed threaded holes, and a first ball-type plunger is installed in each threaded hole; the space formed by the center circular ring plate of the integrated plate and the center hole of the first aluminum connector is used to allow a milling cutter to pass through the integrated plate; the plane where the ball vertices of all the first ball-type plungers are located is higher than the end face of the first magnetic ring;

[0006] The driven side clamp includes a circumferential clamping component and a central support component; the circumferential clamping component includes a second aluminum connecting member, a second magnetic ring, a coil and a coil housing, the two end surfaces of the second aluminum connecting member are respectively provided with a first circular boss and a second circular boss, and a center hole; the second magnetic ring is fixed to the rotating surface of the first circular boss, and the end surface of the first circular boss is provided with M circumferentially evenly distributed threaded holes, and a second ball-type plunger is installed in each threaded hole; the coil is embedded in the coil housing, the end face of the coil contacts the end face of the second circular boss, and the coil housing is fixed to the second aluminum connecting member; the plane where the ball vertices of all second ball-type plungers are located is higher than the end face of the second magnetic ring; the space formed by the second aluminum connecting member, the second magnetic ring and the coil is used to accommodate the central support component; the central support component includes a support head, the front end face of the support head is provided with a plurality of spherical protrusions, the rear end of the support head is fixed with a bolt, the bolt is fitted with a third magnetic ring, and the support head and the third magnetic ring are fixed as a whole by a fixing nut;

[0007] The axial dimension of the bolt head is L1, the axial dimension of the support head is L2, and the axial movement stroke of the central support component is L, L=L1+L2; the axial dimension of the first magnetic ring is H1, the axial dimension of the second magnetic ring is H2, and the axial dimension of the third magnetic ring is H3, H1=3×H2; H3=2×H2; the axial dimension of the coil is H4, H4=2×H2; the axial dimension of the second aluminum connector is L3, the axial dimension of the first circular boss is L4, and the axial dimension from the end face of the second magnetic ring to the end face of the coil is H2+L3-L4+H4; the second The axial travel of the ball of the ball-type plunger is ΔL. The distance between the plane where the ball vertices of all second ball-type plungers are located and the end face of the second magnetic ring is L5, where L5 = ΔL. The outer diameter of the second aluminum connector is D1, and the outer diameters of the first and second magnetic rings are both D2, where D1 > D2. The center hole of the second aluminum connector and the inner diameter of the coil are both D3, and the outer diameter of the third magnetic ring is D4, where D3 - D4 = 1.0 mm. The inner diameter of the coil housing is D5, and the outer diameter of the coil and the outer diameter of the second circular boss in contact therewith are both D6, where D5 - D6 = 1.0 mm.

[0008] The magnetic pole directions of the first magnetic ring and the second magnetic ring are consistent, and the magnetic pole directions of the third magnetic ring and the second magnetic ring are opposite;

[0009] The three wing plates of the integrated board are provided with threaded holes for fixing the active side fixture to the main shaft of the milling equipment; the driven side fixture is adsorbed on the opposite side of the active side fixture by magnetic force.

[0010] Furthermore, the magnetic point contact adaptive clamp of the present invention, wherein:

[0011] The structure of the first ball-type plunger is that the first ball-type plunger includes a main body, a blind hole is provided at the front end of the main body, a support spring and a ball component are provided in the blind hole, the ball component includes a ball seat, an anti-slip ring is provided at the front end of the ball seat, a central main ball is embedded in the ball seat, 2-3 peripheral auxiliary small balls are provided between the bottom of the ball seat and the central main ball; the central main ball and the inner wall of the ball seat are in a sliding fit, the depth of the ball seat is H, the radius of the central main ball is R, and the radius of the peripheral auxiliary small balls is r, HR<r, and r=(0.6~0.7)R; under the action of the support spring, the ball component moves axially; the structure of the second ball-type plunger is the same as that of the first ball-type plunger.

[0012] The first aluminum connector is fixed to the integrated board by using a plurality of first fastening screws; the first magnetic ring is bonded to the outer rotating surface of the concentric positioning boss by using strong glue.

[0013] The second magnetic ring and the rotating surface of the first circular boss are bonded with strong glue; the fixing structure of the coil housing and the second aluminum connecting piece is that the rotating surface of the second circular boss and the coil housing are each provided with a plurality of one-to-one corresponding radial threaded holes, and the coil housing and the second circular boss are fixed by a plurality of second fastening screws.

[0014] The bolt is fixed to the rear end of the support head by using strong glue.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] In the clamp of the present invention, the two clamping sides are connected by magnetic force, such as the active side clamp and the driven side clamp clamp the workpiece by the adsorption force between the magnetic rings, so that contactless connection and control can be achieved within a certain distance. The clamp of the present invention has a simple structure, small size, and light weight, which facilitates the synchronous movement of the milling cutter and the clamp during the feeding process; the clamp is more conducive to fitting the local processing position of the workpiece, avoiding the flexible design required for the clamp to adapt to the curved surface. Among them, the ball-type plungers in the clamping parts on both sides are integrated with support springs, which can extend and retract while rolling, further enhancing the adaptability to the workpiece surface, so that no matter whether the workpiece has a thickness change or a curved surface, it can maintain a good point contact state with the balls on both sides of the clamp, thereby improving the clamping efficiency of the clamp. In the clamp of the present invention, a structural method is designed in which the balls and the spherical protrusions on the support head contact the workpiece, avoiding the scratches on the workpiece surface caused by direct contact with the magnet, and at the same time facilitating the smooth and continuous movement of the clamp.

[0017] In this invention, when the active clamp is attached to the passive clamp, the central support component is subjected to the magnetic and electromagnetic forces of the circumferential clamping components. Simultaneously, it is balanced by the support force from the workpiece, resulting in a reaction force acting on the workpiece. By rationally designing the relative distance between the central and circumferential components, the adsorption force exerted on the central support component is effectively utilized. Based on this, the magnitude of the force between the two components is adjusted using current, thereby achieving adjustment of the workpiece support force. In this invention, the control of the magnet by an energized coil generates a support force that can be adjusted in real time, thereby matching the milling force. The magnitude of the support force can be precisely calculated based on the workpiece thickness and the control current, resulting in an accurate and rapid response and a wide adjustment range.

[0018] During the design process of the present invention, the possibility of lag in the follow-up of the driven side fixture when the milling cutter is fed is taken into consideration. Therefore, the diameter of the support head is larger than the diameter of the milling cutter, which can still provide effective support during lag and avoid the mismatch between the milling point and the support point.

[0019] In summary, the fixture designed in the present invention has good adaptability and adjustability, and can adapt to workpieces of various shapes, such as wedges, curved surfaces and flat plates; at the same time, it can adapt to various processing conditions, such as variable axial cutting depth, variable speed, etc.; the overall structure is lightweight and compact, the assembly and disassembly process is simple, and it has a significant effect on suppressing the vibration and deformation of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an overall schematic diagram of the magnetic point-contact adaptive fixture for thin-wall workpiece milling according to the present invention;

[0021] Figure 2 Schematic cross-sectional view of the magnetic point-contact adaptive fixture for thin-wall workpiece milling according to the present invention;

[0022] Figure 3 for Figure 1 The structural diagram of the active side clamp is shown in FIG;

[0023] Figure 4 for Figure 3 The structural exploded view of the active side clamp is shown;

[0024] Figure 5 for Figure 1 Exploded view of the structure of the circumferential clamping component of the driven side clamp shown in FIG;

[0025] Figure 6 for Figure 1 The structural exploded view of the central supporting component of the driven side clamp shown in FIG;

[0026] Figure 7-1 for Figure 1 Schematic diagram of the state before the driven side fixture and the active side fixture are adsorbed;

[0027] Figure 7-2 for Figure 7-1 A cross-sectional view of the state shown in ;

[0028] Figure 8-1 for Figure 1 Schematic diagram of the state after the driven side fixture and the active side fixture are adsorbed;

[0029] Figure 8-2 for Figure 8-1 A cross-sectional view of the state shown in ;

[0030] Figure 9 A schematic diagram of the magnetic force directions of the three magnetic rings in the fixture of the present invention and their relative positions with the coil and the workpiece;

[0031] Figure 10 The support force of the present invention changes with the current under different workpiece thicknesses;

[0032] Figure 11 for Figure 4 A half-section view of the first ball-type plunger shown in FIG;

[0033] Figure 12-1 for Figure 1 The workpiece shown in is a partial schematic diagram of a curved workpiece;

[0034] Figure 12-2 for Figure 1 The workpiece described in the figure is a partial schematic diagram of a workpiece with variable thickness.

[0035] In the picture:

[0036] 1- milling cutter 2- active side fixture 21- first ball type plunger 211- center main ball

[0037] 212- peripheral auxiliary small ball 213- support spring 214- ball seat 215- main body

[0038] 22-first magnetic ring 23-first aluminum connector 24-integrated board 25-first fastening screw

[0039] 3-Workpiece 31-Curved workpiece 32-Varied thickness workpiece 4-Driven side fixture

[0040] 41- Circumferential clamping component 411- Second ball-type plunger 412- Second magnetic ring 413- Second aluminum connector

[0041] 414-coil 415-coil housing 416-second fastening screw 42-center support component

[0042] 421-Support head 422-Bolt 423-Third magnetic ring 424-Fixing nut DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention in any way.

[0044] like Figure 1 and Figure 2 As shown, the present invention proposes a magnetic point-contact adaptive fixture for milling thin-walled workpieces, which includes an active side fixture 2 and a driven side fixture 4.

[0045] like Figure 3 and Figure 4As shown, the active-side fixture 2 includes an integrated plate 24, which comprises a central annular plate with three wing plates evenly spaced around the central annular hole. A first aluminum connector 23 with a central hole is fixed to one side of the integrated plate 24, secured therebetween by multiple first fastening screws 25. The central hole is intended for passing a milling cutter. Threaded holes are provided on the three wing plates of the integrated plate 24 for securing the active-side fixture 2 to the spindle of the milling machine. The driven-side fixture 4 is magnetically attached to the opposite side of the active-side fixture 2. The outer side of the first aluminum connector 23 is provided with a concentric positioning boss. A first magnetic ring 22 is bonded to the outer rotating surface of the concentric positioning boss using strong glue. The end face of the concentric positioning boss is provided with N circumferentially evenly distributed threaded holes (in this embodiment, N = 6), each of which is fitted with a first ball-type plunger 21. The space formed by the central annular plate of the integrated plate 24 and the center hole of the first aluminum connector 23 allows the milling cutter 1 to pass through the integrated plate 24. The ball apex of all first ball-type plungers 21 lies in the same plane, which is higher than the end face of the first magnetic ring 22. The active-side fixture 2 is an annular structure with a central space reserved for the milling cutter 1 to pass through. The balls at the top of the first ball-type plungers 21 are each elevated a certain distance above the first magnetic ring 22, ensuring that, during use, the first magnetic ring 22 does not contact the workpiece 3, but the first ball-type plungers 21 do. This ensures smoother feeding with the milling cutter 1.

[0046] The driven side clamp 4 includes a circumferential clamping part 41 and a central supporting part 42. Figure 5 、 Figure 6 、 Figure 7-1 and Figure 8-1 shown.

[0047] like Figure 5As shown, the circumferential clamping component 41 includes a second aluminum connector 413, a second magnetic ring 412, a coil 414 and a coil housing 415. The two end surfaces of the second aluminum connector 413 are respectively provided with a first circular boss and a second circular boss, and a center hole; the second magnetic ring 412 is fixed to the rotating surface of the first circular boss by strong glue, and the end surface of the first circular boss is provided with M circumferentially uniformly distributed threaded holes. In this embodiment, M=6, and each threaded hole is installed with a first threaded hole. Two ball-type plungers 411 are provided. The coil 414 is embedded in a coil housing 415, with the end face of the coil 414 contacting the end face of the second circular boss. The coil housing 415 is fixed to the second aluminum connector 413. The fixing structure is that the rotating surface of the second circular boss and the coil housing 415 are each provided with a plurality of corresponding radial threaded holes. In this embodiment, four radial threaded holes are provided. The coil housing 415 and the second circular boss are fixed by four second fastening screws 416. The various components of the circumferential clamping member 41 are rigidly connected together, and the overall structure is annular.

[0048] The vertices of the balls of all the second ball-type plungers 411 are located in the same plane, and the plane is higher than the end surface of the second magnetic ring 412; the space formed by the second aluminum connector 413, the second magnetic ring 412 and the coil 414 is used to accommodate the central support component 42, which is located at the center of the circumferential clamping component 41, corresponding to the milling position of the milling cutter, and is connected only by the adsorption force between the two parts of the magnetic ring, and can move up and down along the axial direction; Figure 7-2 and Figure 8-2 shown.

[0049] In the driven-side fixture 4 , the arrangement of the six second ball-type plungers 411 and the second magnetic ring 412 is consistent with that of the first ball-type plungers 21 and the first magnetic ring 22 on the active-side fixture 2 .

[0050] like Figure 6 As shown, the central support component 42 includes a support head 421. The front surface of the support head 421 is provided with multiple spherical protrusions to achieve point contact with the workpiece, replacing surface contact with multiple points, thereby reducing friction and scratches on the workpiece. The rear end of the support head 421 is fixed with a bolt 422 using strong glue. The bolt 422 is mounted on the third magnetic ring 423, and the support head 421 and the third magnetic ring 423 are fixed together by a fixing nut 424.

[0051] In the present invention, the axial dimension of the head of the bolt 422 is L1, the axial dimension of the support head 421 is L2, and the axial movement stroke of the central support component 42 is L, L=L1+L2; the axial dimension of the first magnetic ring 22 is H1, the axial dimension of the second magnetic ring 412 is H2, and the axial dimension of the third magnetic ring 423 is H3, H1=3×H2; H3=2×H2; the axial dimension of the coil is H4, H4=2×H2.

[0052] The axial dimension of the second aluminum connector 413 is L3, the axial dimension of the first circular boss is L4, and the axial dimension from the end face of the second magnetic ring 412 to the end face of the coil 414 is H2+L3-L4+H4; the axial movement stroke of the ball of the second ball-type plunger 411 is △L, and the distance between the plane where the ball vertices of all second ball-type plungers 411 are located and the end face of the second magnetic ring 412 is L5, L5=△L, so that the magnet is only used to provide adsorption force and only the ball is in contact with the workpiece.

[0053] The outer diameter of the second aluminum connecting member 413 is D1, and the outer diameters of the first magnetic ring 22 and the second magnetic ring 412 are both D2, D1>D2; the center hole of the second aluminum connecting member 413 and the inner diameter of the coil 414 are both D3, and the outer diameter of the third magnetic ring 423 is D4, D3-D4=1.0mm; the inner diameter of the coil housing 415 is D5, and the outer diameter of the coil 414 and the outer diameter of the second circular boss in contact with it are both D6, D5-D6=1.0mm.

[0054] like Figure 11As shown, in the present invention, the structure of the first ball-type plunger 21 is that the first ball-type plunger 21 includes a main body 215, a blind hole is provided at the front end of the main body 215, a support spring 213 and a ball component are provided in the blind hole, the ball component includes a ball seat 214, an anti-slip ring is provided at the front end of the ball seat 214, a central main ball 211 is embedded in the ball seat 214, 2-3 peripheral auxiliary small balls 212 are provided between the bottom of the ball seat 214 and the central main ball 211; between the central main ball 211 and the inner wall of the ball seat 214 To achieve a sliding fit, the ball seat 214 has a depth of H, the central main ball 211 has a radius of R, and the peripheral auxiliary small balls 212 have a radius of r, where HR < r and r = 0.6-0.7R. Under the action of the support spring 213, the ball assembly moves axially. Under the action of the support spring 213, the ball seat 214 and the central main ball 211 and peripheral auxiliary small balls 212 therein can move axially, thereby enhancing the adaptability of the active side fixture 2 and the driven side fixture 4 to the surfaces of the curved workpiece 31 and the workpiece with variable thickness 32 within a small local area. The structure of the second ball-type plunger 411 is the same as that of the first ball-type plunger 21.

[0055] During the milling process, the driven-side fixture 4 is magnetically attracted to the opposite side of the active-side fixture 2. Primarily, the circumferential clamping component 41 is attracted to the active-side fixture 2, while the central support component 42 is connected. During the milling process, the fixture of the present invention maintains synchronous movement with the milling cutter 3. The active-side fixture 2 and the circumferential clamping component 41 clamp the workpiece, increasing its normal stiffness and preventing severe vibration and deformation of the workpiece 3. The central support component 42 further adjusts the magnitude of the supporting force acting on the workpiece 3 through the current in the coil 414, thereby improving material removal rate and machining accuracy. Specifically, in the present invention, the central support component 42 is positioned at the center of the circumferential clamping component 41 and is movable axially. In the natural state of the driven-side fixture 4, no current flows in the coil 414, and the central support component 42 is maintained in a balanced position by the attraction force between the second magnetic ring 412 and the third magnetic ring 423. When the active-side fixture 2 and the driven-side fixture 4 are attracted to the sides of the workpiece 3, the driven-side fixture 4 is in a compressed state. Because the workpiece 3 is flat or nearly flat in the clamped portion, the central support component 42 moves axially to a new equilibrium position, where the apex of the spherical support head 421 of the central support component 42 and the top of the second ball-type plunger 411 of the axial clamping portion 41 are coplanar. In the compressed state, the central support component 42 experiences an attractive force from the second magnetic ring 412 and the first magnetic ring 22. This attractive force can be further modified by adjusting the current in the coil 414. When the driven-side clamp 4 is in the compressed state, the central support component 42 also experiences a supporting force from the workpiece 3 to maintain equilibrium. This supporting force, along with the supporting force applied by the central support component 42 on the workpiece 3, forms a pair of action and reaction forces. Therefore, the combined magnetic and electromagnetic forces acting on the central support component 42 are equal to the supporting force applied by the central support component 42 on the workpiece. Therefore, the driven-side clamp 4 provides a support force for the workpiece 3 that can be adjusted in real time at the milling point.

[0056] When the coil 414 adjusts the electromagnetic force applied to the central support member 42 by energizing it, the coil 414 is simultaneously subjected to a reaction force. Therefore, for the circumferential clamping device 41, its second magnetic ring 412 and energized coil 414 are both subject to the adsorption force from the active-side clamp 2 and the adsorption force from the central support member 42. Among these forces, the adsorption force between the first magnetic ring 22 and the second magnetic ring 412, due to their larger size and smaller spacing, is the primary guarantee for the adsorption between the active-side clamp 2 and the passive-side clamp 4. This adsorption force is sufficiently large to allow the coil 414 to adjust the interaction force between the circumferential clamp 41 and the central support member 42 without causing any of them to fall due to insufficient adsorption force. For the passive-side clamp 4 as a whole, it is subject to the adsorption force from the first magnetic ring 22 in the active-side clamp 2 on the second magnetic ring 412, the third magnetic ring 422, and the coil 414. This adsorption force is not affected by the current, but only by the thickness of the workpiece. This requires that the thickness of the workpiece that the clamp can clamp should remain within a certain range. Since the second magnetic ring 412 and the coil 414 are rigidly fixed via the second aluminum connector 413 and the coil housing 415 , the interaction force between the two is not considered.

[0057] like Figure 3 、 Figure 7-1 、 Figure 8-1 and Figure 11 As shown, the first ball-type plunger 21 of the active-side device 2 and the second ball-type plunger 411 of the passive-side fixture 4 are identical. The first ball-type plunger 21 is composed of a central main ball 211, peripheral auxiliary small balls 212, a support spring 213, a ball seat 214, and a body 215. Under the action of the support spring 213, the ball seat 214 and the central main ball 211 and peripheral small balls 212 therein can move axially, thereby enhancing the adaptability of the active-side fixture 2 and the passive-side fixture 4 to the surfaces of the curved workpiece 31 and the workpiece with variable thickness 32 within a small local area.

[0058] like Figure 9 As shown, in the present invention, the magnetic pole arrangement of the first magnetic ring 22, the second magnetic ring 412 and the third magnetic ring 423 should follow that the magnetic pole directions of the first magnetic ring 22 and the second magnetic ring 412 are consistent, and the magnetic pole directions of the third magnetic ring 423 and the second magnetic ring 412 are opposite.

[0059] The working process of the device of the present invention is as follows: before the start of processing, the active side fixture 2 is installed on the main shaft of the robot, the milling cutter 3 is fixed on the robot and passes through the active side fixture 2, and the milling cutter 3 is higher than the ball of the active side fixture 2 by a certain height, which is equal to the axial cutting depth of milling. The robot is positioned to the starting point of the milling path and fed to the axial cutting depth, and the driven side fixture 4 is adsorbed on the opposite side of the active side fixture 2, and the two are in a mirror image relationship. Then horizontal feeding is performed and processing is performed to the end of the path. In this process, the changing cutting depth or workpiece thickness will lead to changing cutting force, so the current can be adjusted to match the supporting force with the cutting force. At the same time, the clamping action between the active and driven side fixtures 2 and 4 provides out-of-plane stiffness for the workpiece 3, suppressing the vibration and deformation of the workpiece 3 in the out-of-plane direction. After milling is completed, the driven side fixture 4 can be directly removed and the tool can be retracted.

[0060] Example

[0061] A TriMule-600 hybrid robot was used to conduct milling tests on thin-walled workpieces. The workpiece shapes included wedges, flat plates, and cylindrical surfaces. The wedges had thicknesses gradually varying from 2mm to 3mm, and were 380mm long and 300mm wide. The flat plates were 2mm thick, 300mm long and wide, and 300mm wide. The cylindrical surfaces were 3mm thick, 400mm long and wide, with a radius of curvature of 1m. One edge of the workpiece was symmetrically fixed in a vise with a clamping area of ​​160mm long and 45mm wide. The milling cutter had 3 teeth and a radius of 6mm.

[0062] The dimensions of the clamps of the present invention are as follows: the active-side clamp 2 has a height of 11.17 mm, a clamping radius of 20 mm, and an outer diameter of 170 mm; the passive-side clamp 4 has an overall height of 25 mm, an outer diameter of 63 mm, and an overall mass of 0.201 kg, of which the central support member has a mass of 0.055 kg. In this embodiment, the height values ​​refer to the axial dimensions.

[0063] The overall structure of the clamp is arranged in sequence from the active side to the driven side.

[0064] The active side device 2 mainly includes a first ball-type plunger 21, a first magnetic ring 22, a first aluminum connector 23, an integrated board 24 and a fastening screw 25. The overall height of the first ball-type plunger 21 is 13.8 mm, wherein the central main ball 211 can retract within a range of 0.8 mm, and the stiffness of the support spring 213 is 3.68e4 N / m; the inner diameter of the first magnetic ring 22 is 54 mm, the outer diameter is 62 mm, and the height is 15 mm; the overall height of the first aluminum connector is 15 mm, wherein a 12.4 mm high circular boss is provided on the bottom surface with a thickness of 2.6 mm, and the first magnetic ring 22 is fixed to this boss with strong glue, and three groups of M3 threaded holes are evenly distributed along its circumference for connecting to the integrated board 24, and the three groups of threaded holes are all located at a diameter of 50 mm. On the circle, six groups of M6 threaded holes are evenly distributed along its circumference for connecting the first ball-type plunger 21, which are evenly arranged along the circumference on a circle with a diameter of 40 mm. The first ball-type plunger 21 is 1.2 mm higher than the first magnetic ring 22; the overall outline diameter of the integrated board 24 is 170 mm, and the thickness is 5 mm. A through hole with a diameter of 40 mm is reserved in the center for the milling cutter 3 to pass through. Three pairs of M3 threaded holes are evenly distributed at a position with a diameter of 50 mm for fixing the first aluminum connector 23. Three groups of M5 and M6 threaded holes are alternately reserved at a position with a diameter of 140 mm for connecting the milling robot.

[0065] The driven side fixture 4 includes a circumferential connection part 41 and a central support part 42. The circumferential connection part 41 is installed with a plurality of second ball-type plungers 411 and second magnetic rings 412 corresponding to the active side fixture 2. The height of the second magnetic ring 412 is 5mm, and its inner and outer diameters are consistent with those of the first magnetic ring 22. The second ball-type plunger 411 and the second magnetic ring 412 are fixed to the second aluminum connector 413 by threads and strong glue respectively. The second ball-type plunger 411 is 0.8mm higher than the second magnetic ring 412. The second aluminum connector 413 has an overall height of 10mm and a diameter of 31.5mm. Bosses with heights of 2mm and 5mm are provided on the upper and lower parts respectively. The upper boss has a diameter of 53.8mm and is used to fix the second magnetic ring 412. At the same time, six M6 threaded holes are evenly distributed at a circumferential diameter of 40mm. The lower boss has a diameter of 47.4mm. Four M2.5 threaded holes are reserved along the circumference. Used to connect the coil housing 415, a through hole with a diameter of 31mm is reserved at the center position of the second aluminum connector for placing the central support component 42; the coil 414 has an inner diameter of 31mm, an outer diameter of 47mm, and a height of 10mm, and is placed in the coil housing 415; the overall height of the coil housing 415 is 17mm, the outer diameter is 52mm, the wall thickness is 2mm, the bottom thickness is 2mm, and a through hole with a diameter of 52mm is reserved on the bottom surface to facilitate the penetration and movement of the central support component 42. Four circumferentially distributed through holes with a diameter of 3mm are arranged at a distance of 2.5mm from the upper edge. The fastener 416 is connected to the four circumferential threaded holes of the second aluminum connector 413. Four rectangular through holes with a length of 26mm and a width of 10mm are arranged circumferentially on the bottom surface of the coil housing 415 for heat dissipation of the coil 414 and reducing the structural quality. The central support component 42 includes a spherical support head 421 pasted on an M10 nut 422. The support head has an outline diameter of 30 mm and a height of 3.5 mm, of which the height of the protrusion is 1.5 mm. The top thickness of the nut 422 is 3 mm, and the screw part is 15 mm long. The third magnetic ring 423 passes through the screw part of the nut 422 and is fixed by the M10 nut.

[0066] During the cooperation between the active side fixture 2 and the driven side fixture 4, the fixture moves synchronously with the milling cutter, clamps the workpiece near the milling point, and further supports the workpiece at the milling point, thereby improving the out-of-plane stiffness of the workpiece, reducing vibration and deformation, and thus improving cutting quality and efficiency.

[0067] After testing: the assembly of the present invention adopts a rigid connection method, and each part is rigidly connected, so that the overall structure is stable and durable; the clamps are connected by magnetic force, allowing contactless control within a certain range, and at the same time, the electromagnetic force is regulated by current to further generate real-time adjustable support force; the retractable ball further enhances the adaptability of the clamp to the workpiece surface, thereby making the clamp universal; the point contact method between the ball and the support head reduces the friction during the following process, protects the workpiece and ensures smooth feeding without jamming; the clamp is easy to install and disassemble and can be reused.

[0068] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many improvements and changes without departing from the purpose of the present invention, which are all protected by the present invention.

Claims

1. A magnetic point contact adaptive clamp for milling thin-walled workpieces, comprising an active side clamp (2) and a driven side clamp (4), characterized in that: The active side fixture (2) includes an integrated plate (24), the integrated plate (24) includes a central annular plate, and three wing plates are evenly distributed along the circumference of the central annular hole. A first aluminum connector (23) with a central hole is fixed to one side of the integrated plate (24), and a concentric positioning boss is provided on the outer side of the first aluminum connector (23). A first magnetic ring (22) is fixed on the outer rotating surface of the concentric positioning boss, and an end face of the concentric positioning boss is provided with N circumferentially evenly distributed threaded holes, and a first ball-type plunger (21) is installed in each threaded hole; the space formed by the central annular plate of the integrated plate (24) and the central hole of the first aluminum connector (23) is used to allow the milling cutter (1) to pass through the integrated plate (24); The ball vertices of all first ball-type plungers (21) are located in the same plane, and the plane is higher than the end surface of the first magnetic ring 22; The driven side clamp (4) includes a circumferential clamping component (41) and a central supporting component (42); The circumferential clamping component (41) includes a second aluminum connector (413), a second magnetic ring (412), a coil (414) and a coil housing (415); the two end surfaces of the second aluminum connector (413) are respectively provided with a first circular boss and a second circular boss, and are also provided with a center hole; the second magnetic ring (412) is fixed to the rotating surface of the first circular boss; the end surface of the first circular boss is provided with M circumferentially evenly distributed threaded holes, and a second ball-type plunger (411) is installed in each threaded hole; The coil (414) is embedded in the coil housing (415), the end face of the coil (414) contacts the end face of the second circular boss, and the coil housing (415) is fixed to the second aluminum connector (413); the plane where the vertices of the balls of all second ball-type plungers (411) are located is higher than the end face of the second magnetic ring (412); the space formed by the second aluminum connector (413), the second magnetic ring (412) and the coil (414) is used to accommodate the central support component (42); The central support component (42) includes a support head (421), a front end surface of the support head (421) is provided with a plurality of spherical protrusions, a rear end of the support head (421) is fixed with a bolt (422), a third magnetic ring (423) is sleeved on the bolt (422), and the support head (421) and the third magnetic ring (423) are fixed together by a fixing nut (424); The axial dimension of the head of the bolt (422) is L1, the axial dimension of the support head (421) is L2, and the axial movement stroke of the central support component (42) is L, where L=L1+L2; The axial dimension of the first magnetic ring (22) is H1, the axial dimension of the second magnetic ring (412) is H2, and the axial dimension of the third magnetic ring (423) is H3, H1=3×H2; H3=2×H2; the axial dimension of the coil is H4, H4=2×H2; The axial dimension of the second aluminum connector (413) is L3, the axial dimension of the first circular boss is L4, and the axial dimension from the end face of the second magnetic ring (412) to the end face of the coil (414) is H2+L3-L4+H4; the axial movement stroke of the ball of the second ball-type plunger (411) is ΔL, and the ball vertices of all the second ball-type plungers (411) are located in the same plane, and the distance between the plane and the end face of the second magnetic ring (412) is L5, and L5=ΔL; The outer diameter of the second aluminum connecting member (413) is D1, and the outer diameters of the first magnetic ring (22) and the second magnetic ring (412) are both D2, with D1>D2; the inner diameters of the center hole of the second aluminum connecting member (413) and the coil (414) are both D3, and the outer diameter of the third magnetic ring (423) is D4, with D3-D4=1.0 mm; the inner diameter of the coil housing (415) is D5, and the outer diameter of the coil (414) and the outer diameter of the second circular boss in contact therewith are both D6, with D5-D6=1.0 mm; The magnetic pole directions of the first magnetic ring (22) and the second magnetic ring (412) are consistent, and the magnetic pole directions of the third magnetic ring (423) and the second magnetic ring (412) are opposite; The three wing plates of the integrated board (24) are provided with threaded holes for fixing the active side fixture (2) to the main shaft of the milling equipment; the driven side fixture (4) is adsorbed on the opposite side of the active side fixture (2) by magnetic force.

2. The magnetic point contact adaptive fixture for thin-wall workpiece milling according to claim 1, characterized in that: The structure of the first ball-type plunger (21) is that the first ball-type plunger (21) includes a main body (215), a blind hole is provided at the front end of the main body (215), a support spring (213) and a ball component are provided in the blind hole, the ball component includes a ball seat (214), an anti-slip ring is provided at the front end of the ball seat (214), a central main ball (211) is embedded in the ball seat (214), and the bottom of the ball seat (214) is connected to the central main ball 2-3 peripheral auxiliary small balls (212) are arranged between the balls (211); the central main ball (211) and the inner wall of the ball seat (214) are in sliding fit, the depth of the ball seat (214) is H, the radius of the central main ball (211) is R, the radius of the peripheral auxiliary small balls (212) is r, HR<r, and r=(0.6~0.7)R; under the action of the support spring (213), the ball component moves in the axial direction; The structure of the second ball-type plunger (411) is the same as that of the first ball-type plunger (21).

3. The magnetic point contact adaptive fixture for thin-wall workpiece milling according to claim 1, characterized in that: The first aluminum connector (23) and the integrated board (24) are fixed with a plurality of first fastening screws (25); and the first magnetic ring (22) and the outer rotating surface of the concentric positioning boss are bonded with strong glue.

4. The magnetic point contact adaptive fixture for thin-wall workpiece milling according to claim 1, characterized in that: The second magnetic ring (412) is bonded to the rotating surface of the first circular boss by strong glue; the fixing structure of the coil housing (415) and the second aluminum connecting member (413) is that a plurality of one-to-one corresponding radial threaded holes are provided on the rotating surface of the second circular boss and the coil housing (415), and the coil housing (415) is fixed to the second circular boss by a plurality of second fastening screws (416).

5. The magnetic point contact adaptive fixture for thin-wall workpiece milling according to claim 1, characterized in that: The bolt (422) is fixed to the rear end of the support head (421) by using strong glue.

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