Double-tool conjugate milling device and method for suppressing vibration deformation of excess edge of skin

Abstract

The present application relates to a kind of double-tool conjugate milling chatter deformation synchronous inhibition device and method of excess edge of skin, by the same speed of saw blade cutter on two milling cutters conjugate opposite direction rotation, upper and lower surface of weak rigid skin is simultaneously milled, the removal of weak rigid skin edge excess is realized.Two milling cutters produce the milling force of interaction and offset each other, processing is stable, avoid the problem that weak rigid skin machining chatter / deformation and edge burr and unevenness are caused by the change of milling force constantly.

Description

Technical Field

[0001] This invention relates to the field of automated milling technology for weakly rigid skin, and in particular to a device and method for synchronously suppressing chatter deformation during double-blade conjugate milling of redundant edges on skin. Background Technology

[0002] Aircraft equipment represents a nation's advanced manufacturing capabilities. Aircraft weight is a key factor in improving its maneuverability. To reduce aircraft weight while meeting structural strength and performance requirements, numerous thin-walled components are widely used in critical aircraft parts. Among these, the skin, as an aerodynamic shape component, is widely used in various passenger and fighter jets. Aircraft skin materials include aluminum alloys, titanium alloys, and stainless steel. Aircraft skin is generally formed by stretching using dies to create the designed profile. However, stretched skins often have excess edges, making it difficult to meet the precision requirements of aircraft assembly.

[0003] To obtain precise aircraft skin dimensions, milling technology is used to remove excess material from the skin edges. Milling the skin ensures dimensional accuracy, normal accuracy, and cut roughness, thus facilitating subsequent assembly. Milling is an economical and quick method. By milling, the gaps at the skin seams meet design requirements, thereby controlling surface variations and gaps to achieve stealth performance. As a critical step in skin manufacturing, the precision of milling directly impacts subsequent assembly production.

[0004] Due to the characteristics of skin, such as large spatial dimensions, thin walls and weak rigidity (sometimes only 1-2 mm thick), and the presence of many difficult-to-machine materials (titanium alloys and composite materials), its machinability is poor. During skin milling, under the dynamic cutting force, chatter / deformation instability easily occurs at the contact point between the workpiece and the tool, directly reducing workpiece machining accuracy and surface quality, and indirectly shortening tool life and limiting machine tool efficiency. Therefore, ensuring efficient and stable skin milling has become one of the technical challenges restricting aircraft manufacturing production efficiency. To avoid chatter / deformation problems caused by weak rigidity, researchers often choose conservative process parameters, using lower spindle speeds and cutting parameters to minimize these problems. However, this empirical method not only makes it difficult to fully utilize the performance of machine tools and cutting tools, but also significantly reduces machining efficiency, extends product production cycles, and cannot fundamentally eliminate chatter / deformation. Therefore, how to avoid chatter / deformation caused by weak rigidity has become a highly concerned cutting-edge issue, and it is of great significance to suppress milling chatter / deformation at its source. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a device and method for synchronously suppressing chatter and deformation during double-cutter conjugate milling of skin with excess edges. By having two saw blade milling cutters on the cutter holders rotate in opposite directions at the same rotation speed, the upper and lower surfaces of the weak rigid skin are milled simultaneously, thereby removing the excess material at the edges of the weak rigid skin. The milling forces generated by the two milling cutters interact with each other and cancel each other out, resulting in stable processing and avoiding chatter / deformation, edge burrs, unevenness, and other problems caused by continuous changes in milling force during the processing of the weak rigid skin.

[0006] The technical solution adopted in this invention is as follows:

[0007] This invention proposes a device for synchronously suppressing chatter deformation during double-blade conjugate milling of weakly rigid skin with redundant edges. The device includes a housing, flange bearings, spur gears, saw blade milling cutters, milling cutter shanks, a coupling, and a brushless motor. The milling cutter shanks are horizontally arranged on the upper and lower sides of the middle of the housing and vertically aligned. Both sides of the milling cutter shanks are connected to the housing via flange bearings. Spur gears are coaxially fixed to the middle of each milling cutter shank, and the spur gears on the upper and lower sides mesh with each other. The saw blade milling cutters are coaxially fixed to the rear side of the milling cutter shanks. The saw blade milling cutters on the rear side of the upper and lower milling cutter shanks are parallel to each other and axially offset, with a very small gap between the discs of the two saw blade milling cutters. The brushless motor is fixed to one end of the housing, and its output end is connected to the lower milling cutter shank via a coupling.

[0008] Furthermore, the saw blade end mill is made of tungsten steel.

[0009] Furthermore, the outer casing includes a top plate, a bottom plate, and a C-shaped plate; the top plate is positioned above one side of the bottom plate; the front and rear sides of the top plate and the bottom plate are connected by C-shaped plates; the upper and lower ends of the C-shaped plate are fixed to the top plate and the bottom plate by bolts, and the upper and lower sides of the middle of the C-shaped plate are respectively provided with round holes corresponding to the milling cutter shank.

[0010] Furthermore, the spur gear is fixed to the milling cutter shank by screws.

[0011] Furthermore, the brushless motor is fixed to the front end of the base plate by a motor bracket.

[0012] A method for synchronously suppressing chatter deformation during double-blade conjugate milling of excess edges in skin fabric, the method comprising the following steps:

[0013] S1. Mill the surface of the weak rigid skin to be processed to a smooth surface;

[0014] S2. The milled weak rigid skin to be processed is clamped by the milling machine pressure plate. The weak rigid skin is clamped by the rotation of the screw on the pressure plate driving the movement of the upper and lower pressure plates. After clamping, the above device is installed on the robot arm.

[0015] S3. The motor speed range is controlled based on the thickness of the weak rigid skin, the diameter of the saw blade milling cutter, the milling force generated during milling, and the size of the milling area; to maintain the stability of the device during milling, the motor speed remains constant during milling.

[0016] S4. After accurately calculating the relevant data of the saw blade end mill and the weak rigid skin, start to precisely control the motor speed according to the relevant data; after determining the motor speed, determine the feed speed provided by the robotic arm according to the speed of the saw blade end mill driven by the motor.

[0017] S5. Since the feeding motion of the device is achieved through the linear motion of the robot arm, the weak rigid skin is placed between the two saw blades and the position of the weak rigid skin is adjusted so that it is placed in the working area and clamped.

[0018] S6. Start the motor to drive the double saw blade milling cutter to work, control the conjugate milling motion of the saw blade milling cutter to cooperate with the linear feed motion of the edge of the weak stiffness skin to process the surface of the weak stiffness skin, so that the excess material at the edge of the weak stiffness skin is removed under the action of milling force.

[0019] S7. Test the chatter effect during milling, determine the cutting amount during the milling process, and perform edge smoothness detection on the edge of the machined workpiece.

[0020] S8. Repeat steps S5-S7 to proceed to the next milling task.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. This invention can accurately remove excess edges of weak rigid skin during milling, and the dual milling cutter saw blades can mill simultaneously, resulting in higher milling efficiency.

[0023] 2. This invention is applicable to milling of different materials and has strong versatility.

[0024] 3. In the milling process, the milling forces generated by the double milling cutter saw blades cancel each other out, avoiding the milling chatter effect of the tool during processing, and making the skin edge smoother after milling.

[0025] 3. The present invention has a compact structure, uses lightweight and corrosion-resistant materials, and connects the various components of the device with screws. By rotating the screw, the head of the screw passes through a mating hole and is inserted into another hole through the thread, thereby generating tension or pressure to connect the two components.

[0026] 4. The present invention has a simple structure, reliable connection, convenient assembly, and high economy and portability. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a device for synchronously suppressing chatter deformation in the redundant edge milling of a weakly rigid skin, as proposed in this invention.

[0028] Figure 2 for Figure 1 A schematic diagram of the side view structure;

[0029] Figure 3 This is a flowchart illustrating the analysis process of the method of the present invention;

[0030] Figure 4 This is a control flowchart of the device of the present invention;

[0031] Figures 5 to 7 This is a schematic diagram showing the processing effects of excess edges on different materials.

[0032] In the attached drawings, the following reference numerals are used: 1-device housing; 2-flange bearing I; 3-spur gear I; 4-flange bearing II; 5-saw blade milling cutter I; 6-milling cutter shank I; 7-saw blade milling cutter II; 8-milling cutter shank II; 9-flange bearing III; 10-spur gear II; 11-flange bearing IV; 12-coupling; 13-brushless motor; 14-motor bracket; 15-top plate; 16-C-shaped plate; 17-bottom plate. Detailed Implementation

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] It should be noted that in the description of this invention, the terms "upper", "lower", "top", "bottom", "one side", "the other side", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not mean that the device or element must have a specific orientation, or be constructed and operated in a specific orientation.

[0035] See appendix Figure 1-2The present embodiment proposes a device for synchronously suppressing chatter deformation during double-blade conjugate milling of weakly rigid skin with redundant edges, comprising a housing 1, a flange bearing I2, a spur gear I3, a flange bearing II4, a saw blade milling cutter I5, a milling cutter shank I6, a saw blade milling cutter II7, a milling cutter shank II8, a flange bearing III9, a spur gear II10, a flange bearing IV11, a coupling 12, a brushless motor 13, and a motor bracket 14.

[0036] The outer casing 1 includes a top plate 15, a C-shaped plate 16, and a bottom plate 17. The top plate is positioned above the rear side of the bottom plate 17. The front and rear sides of the top plate 15 and the bottom plate 17 are connected by the C-shaped plate 16. The upper and lower ends of the C-shaped plate 16 are fixed to the top plate 15 and the bottom plate 17 by bolts, and the upper and lower sides of the middle part of the C-shaped plate 16 are respectively provided with round holes corresponding to the milling cutter shank I6 and the milling cutter shank II8.

[0037] The milling cutter shank I6 and milling cutter shank II8 are horizontally arranged on the upper and lower sides of the middle of the two C-shaped plates 16, respectively, with their vertical directions aligned and passing through the circular holes on the two C-shaped plates 16. The two sides of the milling cutter shank I6 are respectively connected to the corresponding rotating pairs of the upper circular holes of the two C-shaped plates 16 via flange bearings I2 and II4. The two sides of the milling cutter shank II8 are respectively connected to the rotating pairs of the lower circular holes of the two C-shaped plates 16 via flange bearings III9 and IV11. A spur gear I3 is coaxially fixed to the middle of the milling cutter shank I6 by screws. The milling cutter... A spur gear II10 is coaxially fixed to the middle of rod II8 by screws; the spur gear I3 and spur gear II10 mesh with each other; the saw blade milling cutter I5 is coaxially fixed to the rear side of the milling cutter shank I; the saw blade milling cutter II7 is coaxially fixed to the rear side of the milling cutter shank II8; the saw blade milling cutter I5 and the saw blade milling cutter II7 are parallel to each other and their axial positions are offset from each other, and there is a very small gap between the discs of the saw blade milling cutter I5 and the saw blade milling cutter II7; the brushless motor 13 is fixed to the front end of the base plate 17 by the motor bracket 14, and the output end of the brushless motor 13 is connected to the milling cutter shank II8 by the coupling 12.

[0038] In this embodiment, both the saw blade end mill I5 and the saw blade end mill II7 are made of tungsten steel. Tungsten steel is a high-strength cemented carbide with a series of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance, and corrosion resistance. In particular, its high hardness and wear resistance remain essentially unchanged even at a temperature of 500°C, and it still has very high hardness at 1000°C.

[0039] The double-blade conjugate saw blade end mill employs two end mills with an extremely small gap. During milling, due to the minimal gap between the end mills, saw blade end mill I5 and saw blade end mill II7 can mill independently or simultaneously without interference. Furthermore, by offsetting the milling force, the weakly rigid skin after machining maintains neat, smooth edges and is burr-free.

[0040] A method for synchronously suppressing chatter deformation during double-blade conjugate milling of redundant edges in weakly rigid skin, the method specifically includes the following steps:

[0041] S1. Mill the surface of the weak rigid skin to be processed to a smooth surface;

[0042] S2. The milled, weakly rigid skin to be machined is clamped using the milling machine clamping plate.

[0043] The milling machine pressure plate device includes a double-ended threaded screw, a washer nut, a pressure block, a T-nut, and a triangular block. The triangular block has several small steps. The specific position of the pressure block is adjusted by moving the pressure block up and down on the steps. After the position is determined, the pressure plate device is fixed by the T-nut, the double-ended threaded screw, and the washer nut, thereby fixing the weak rigid skin.

[0044] The weak rigid skin is clamped by rotating the screw on the milling machine platen to drive the movement of the upper and lower plates. After clamping, the device is installed on the robotic arm.

[0045] S3. The speed range of the brushless motor 13 is controlled according to the thickness of the weak rigid skin, the diameter of the saw blade end mill I5 and the saw blade end mill II7, the milling force generated during milling, and the size of the milling area; in order to maintain the stability of the device during milling, the speed of the brushless motor 13 remains constant during milling.

[0046] S4. After accurately calculating the relevant data of saw blade end mill I5 and saw blade end mill II7 with the weak rigid skin, start to precisely control the speed of brushless motor 13 according to the relevant data; after determining the speed of brushless motor 13, determine the feed speed provided by the robotic arm according to the speed of saw blade end mill I5 and saw blade end mill II7 driven by brushless motor 13.

[0047] S5. Since the feeding motion of the device of the present invention is achieved by the linear motion of the robot arm, the weak rigid skin is placed between the two saw blades and the position of the weak rigid skin is adjusted so that it is placed in the working area and clamped.

[0048] S6. Start the brushless motor 13 to drive the double saw blade milling cutter to work, control the conjugate milling motion of the saw blade milling cutter to cooperate with the linear feed motion of the edge of the weak stiffness skin to process the surface of the weak stiffness skin, so that the excess material at the edge of the weak stiffness skin is removed under the action of milling force.

[0049] S7. Test the chatter effect during milling, determine the cutting amount during the milling process, and perform edge smoothness detection on the edge of the machined workpiece.

[0050] S8. Repeat steps S5-S7 to proceed to the next milling task.

[0051] The double-blade conjugate saw blade milling method used in this invention is a new milling method. Conjugate refers to a pair that is matched according to a certain rule. In this invention, double-blade conjugate means that two saw blade milling cutters are placed symmetrically with the same rotation speed and opposite directions. When the two cutters contact and process the workpiece, the milling force generated by the cutters when processing the edge of the skin can cancel each other out, thereby avoiding chatter effect.

[0052] The present invention will be further described in detail below with reference to preferred embodiments:

[0053] Preliminary prototype experiments were conducted on the edge milling of the skin, using a Zhongjie GMC1225L CNC machine tool with a drive mechanism for feed motion. The workpieces used in the experiments were pure copper, 2A12 aluminum alloy, and TC4 titanium alloy. First, the workpieces were clamped using a milling machine clamping plate, which included a double-ended threaded screw, a washer nut, a clamping block, and a T-nut. Since copper has relatively lower strength and hardness among the three workpiece types, pure copper was milled first, with a milling width of 6mm, a milling length of 100mm, and a copper thickness of approximately 0.2mm. Four sets of experiments were set up, with the following rotational speed and machine feed rate:

[0054] Table 1. Rotation speed and feed rate of the device during copper milling.

[0055]

[0056] Next, the 2A12 aluminum alloy was milled, with a milling length of 200mm and an alloy thickness of approximately 1mm. Four sets of experiments were set up, with the following settings for the apparatus rotation speed, machine feed rate, and milling width:

[0057] Table 2. Rotation speed and feed rate of the device during aluminum alloy milling.

[0058]

[0059] Finally, the TC4 titanium alloy was milled, with a milling length of 200mm and a titanium alloy thickness of approximately 0.8mm. Two sets of experiments were set up, with the following settings for the apparatus rotation speed, machine tool feed rate, and milling edge width:

[0060] Table 3. Rotation speed and feed rate of the milling device for titanium alloys.

[0061]

[0062] like Figure 5-7As shown, the double-blade conjugate milling method proposed in this invention produces a smooth cut surface, effectively suppresses chatter during the machining process, and results in no deformation of the strip-shaped excess edge or the workpiece after machining.

[0063] All matters not covered in this invention are common knowledge.

[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for synchronously suppressing chatter deformation during double-blade conjugate milling of weakly rigid skin with redundant edges, characterized in that: The device includes a housing, flange bearings, spur gears, saw blade milling cutters, milling cutter shanks, couplings, and a brushless motor. The milling cutter shanks are horizontally arranged on the upper and lower sides of the middle of the housing and vertically aligned. The two sides of the milling cutter shanks are connected to the housing via flange bearings. Spur gears are coaxially fixed to the middle of each milling cutter shank, and the spur gears in the middle of the upper and lower milling cutter shanks mesh with each other. The saw blade milling cutters are coaxially fixed to the rear side of the milling cutter shanks. The saw blade milling cutters on the rear side of the upper milling cutter shank and the rear side of the lower milling cutter shank are parallel to each other and axially offset, with a very small gap between the discs of the two saw blade milling cutters. The brushless motor is fixed to one end of the housing, and the output end of the brushless motor is connected to the lower milling cutter shank via a coupling.

2. The device for synchronously suppressing chatter deformation in double-blade conjugate milling of weakly rigid skin with redundant edges according to claim 1, characterized in that: The saw blade end mill is made of tungsten steel.

3. The device for synchronously suppressing chatter deformation in double-blade conjugate milling of weakly rigid skin with redundant edges according to claim 1, characterized in that: The outer casing includes a top plate, a bottom plate, and a C-shaped plate; the top plate is positioned above one side of the bottom plate; the front and rear sides of the top plate and the bottom plate are connected by C-shaped plates; the upper and lower ends of the C-shaped plate are fixed to the top plate and the bottom plate by bolts, and the upper and lower sides of the middle of the C-shaped plate are respectively provided with round holes corresponding to the milling cutter shank.

4. The device for synchronously suppressing chatter deformation in double-blade conjugate milling of weakly rigid skin with redundant edges according to claim 1, characterized in that: The spur gear is fixed to the milling cutter shank by screws.

5. The device for synchronously suppressing chatter deformation in double-blade conjugate milling of weakly rigid skin with redundant edges according to claim 2, characterized in that: The brushless motor is fixed to the front end of the base plate by a brushless motor bracket.

6. A method for synchronously suppressing chatter deformation during double-blade conjugate milling of redundant edges in weakly rigid skin, implemented using the device described in any one of claims 1-5, characterized in that: The method includes the following steps: S1. Mill the surface of the weak rigid skin to be processed to a smooth surface; S2. The milled weak rigid skin to be processed is clamped by the milling machine pressure plate. The weak rigid skin is clamped by the rotation of the screw on the pressure plate driving the movement of the upper and lower pressure plates. After clamping, the above device is installed on the robot arm. S3. The speed range of the brushless motor is controlled according to the thickness of the weak rigid skin, the diameter of the saw blade milling cutter, the milling force generated during milling, and the size of the milling area; in order to maintain the stability of the device during milling, the speed of the brushless motor remains constant during milling. S4. After accurately calculating the relevant data of the saw blade milling cutter and the weak rigid skin, start to precisely control the speed of the brushless motor according to the relevant data; after determining the speed of the brushless motor, determine the feed speed provided by the robotic arm according to the speed of the saw blade milling cutter driven by the brushless motor. S5. Since the feeding motion of the device is achieved through the linear motion of the robot arm, the weak rigid skin is placed between the two saw blades and the position of the weak rigid skin is adjusted so that it is placed in the working area and clamped. S6. Start the brushless motor to drive the double saw blade milling cutter to work, control the conjugate milling motion of the saw blade milling cutter to cooperate with the linear feed motion of the edge of the weak rigid skin to process the surface of the weak rigid skin, so that the edge excess material of the weak rigid skin is removed under the action of milling force. S7. Test the chatter effect during milling, determine the cutting amount during the milling process, and perform edge smoothness detection on the machined weak rigid skin edge. S8. Repeat steps S5-S7 to proceed to the next milling task.

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