Skin redundant edge double-cutter conjugate milling chatter deformation synchronous suppression device and method

Abstract

According to the skin redundant edge double-cutter conjugate milling chatter deformation synchronous restraining device and method, saw blade milling cutters on two milling cutters rotate in the same rotating speed conjugate opposite directions, the upper surface and the lower surface of a weak-rigidity skin are milled at the same time, and edge margins of the weak-rigidity skin are removed. The milling force generated by the two milling cutters in interaction counteracts each other, machining is stable, and the problems of machining chatter / deformation, edge burrs and unevenness of the weak-rigidity skin caused by continuous change of the milling force are solved.

Description

Technical Field

[0001] The invention relates to the technical field of automatic edge milling of weak-rigidity skins, and in particular to a device and method for synchronously suppressing flutter deformation in double-knife conjugate milling of redundant edges of skins. Background Art

[0002] Aircraft equipment is a representative of a country's high-tech manufacturing level. The weight of an aircraft is a key factor in improving its maneuverability. In order to reduce the weight of the aircraft while meeting its structural strength and performance requirements, a large number of thin-walled components are widely used in key parts of the aircraft. Among them, the skin is widely used in various passenger aircraft and fighter jets as an aerodynamic shape component of the aircraft. The aircraft skin materials include aluminum alloy, titanium alloy and stainless steel. The aircraft skin is generally stretched into a designed surface using a drawing die. However, stretched skin usually has redundant edges, which makes it difficult to meet the aircraft assembly accuracy requirements.

[0003] In order to obtain accurate aircraft skin dimensions, the edge milling technology is required to remove excess hair on the edge of the skin. The purpose of edge milling is to ensure the shape accuracy, normal accuracy and cut roughness of the skin, so as to carry out subsequent assembly. The edge milling method is economical and fast. By edge milling, the gap at the seam of the skin is ensured to meet the design requirements, thereby controlling the step difference and gap on the aircraft surface and achieving the stealth effect of the aircraft. As a key process in skin manufacturing, the processing accuracy of edge milling directly affects the subsequent assembly production.

[0004] Due to the large size, thin wall and weak rigidity (thickness is sometimes only 1-2 mm), and many difficult-to-process materials (titanium alloy and composite materials, etc.), the cutting process performance of the skin is poor. Under the action of dynamic cutting force during the skin edge milling process, chatter / deformation instability is very likely to occur at the contact point between the workpiece and the tool, which directly reduces the machining accuracy and surface quality of the workpiece, indirectly shortens the service life of the tool, and limits the machining efficiency of the machine tool. Therefore, how to ensure efficient and stable edge milling of the skin has become one of the technical problems restricting the production efficiency of aircraft manufacturing. In order to avoid the machining chatter / deformation problems caused by weak rigidity, researchers often choose conservative process parameters and use lower spindle speeds and cutting amounts to avoid such problems as much as possible. However, this empirical method not only makes it difficult to fully utilize the performance of machine tools and tools, but also greatly reduces the machining efficiency, prolongs the production cycle of the product, and cannot fundamentally eliminate the occurrence of chatter / deformation. Therefore, how to avoid machining chatter / deformation caused by weak rigidity has become a hot issue that has attracted much attention, and is of great significance to suppress milling chatter / deformation from the source. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a device and method for synchronously suppressing vibration and deformation of double-cut conjugate milling of multiple redundant edges of skin. The saw blades and milling cutters on the two milling cutter handles rotate in opposite directions at the same speed to simultaneously mill the upper and lower surfaces of the weakly rigid skin, thereby removing the excess on the edge of the weakly rigid skin. The interacting milling forces generated by the two milling cutters offset each other, and the processing is stable, avoiding the problems of vibration / deformation of the weakly rigid skin processing and edge burrs and unevenness caused by the continuous change of the milling force.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention proposes a synchronous suppression device for vibration deformation of double-cutter conjugate milling of weak rigidity skin redundant edges, comprising a housing, a flange bearing, a spur gear, a saw blade milling cutter, a milling cutter rod, a coupling and a brushless motor; the milling cutter rod is horizontally arranged on the upper and lower sides of the middle of the housing and aligned in the vertical direction; the two sides of the milling cutter rod are respectively connected to the housing rotating pair through flange bearings; the middle part of the milling cutter rod is coaxially fixed with a spur gear, and the spur gears in the middle of the milling cutter rods on the upper and lower sides are meshed with each other; the saw blade milling cutters are coaxially fixed to the rear side of the milling cutter rod; the saw blade milling cutter on the rear side of the upper milling cutter rod and the saw blade milling cutter on the rear side of the lower milling cutter rod are parallel to each other and staggered in the axial direction, and a very small spacing is set between the disk surfaces of the two saw blade milling cutters; the brushless motor is fixed at one end of the housing, and the output end of the brushless motor is connected to the lower milling cutter rod through a coupling.

[0008] Furthermore, the saw blade milling cutter is made of tungsten steel.

[0009] Furthermore, the outer shell includes a top plate, a bottom plate and a C-shaped plate; the top plate is correspondingly arranged above one side of the bottom plate; the front and rear sides of the top plate and the bottom plate are respectively connected by C-shaped plates; the upper and lower ends of the C-shaped plate are respectively fixed to the top plate and the bottom plate by bolts, and circular holes corresponding to the milling cutter rod are respectively opened on the upper and lower sides of the middle part of the C-shaped plate.

[0010] Furthermore, the spur gear is fixedly connected to the milling cutter rod by means of screws.

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

[0012] A method for synchronously suppressing flutter deformation in double-knife conjugate milling of skin redundant edges, the method comprising the following steps:

[0013] S1, milling the surface of the weak rigid skin to be processed into a smooth surface;

[0014] S2, clamping the weak rigid skin to be processed after milling through the milling machine pressure plate, wherein the rotation of the screw on the pressure plate drives the movement of the upper and lower pressure plates to achieve the clamping of the weak rigid skin, and after the clamping is completed, the above device is installed on the robot arm;

[0015] S3, controlling the speed range of the motor 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 large milling area; in order to maintain the stability of the device during milling, the speed of the motor is kept constant during milling;

[0016] S4. After accurately calculating the data related to the saw blade milling cutter and the weak rigid skin, the motor speed is precisely controlled according to the relevant data; after determining the motor speed, the feed speed provided by the robot arm is determined according to the saw blade milling cutter speed driven by the motor;

[0017] S5. Since the feeding motion of the device is realized by the linear motion of the robot arm, the weak rigid skin is placed between the two saw blade milling cutters, and the position of the weak rigid skin is adjusted so that it is placed in the working area and clamped;

[0018] S6, starting the motor to drive the double saw blade milling cutter to work, controlling the conjugate milling motion of the saw blade milling cutter and the linear feed motion of the edge of the weak rigidity skin to coordinately process the surface of the weak rigidity skin, so that the excess margin of the edge of the weak rigidity skin is removed under the action of the milling force;

[0019] S7, testing the chatter effect during milling, determining the cutting amount during the milling process, and testing the edge smoothness of the edge of the processed workpiece;

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

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

[0022] 1. The present invention can accurately remove the redundant edges of the weak rigid skin during edge milling. The double milling cutter saw blades perform simultaneous milling, which results in higher edge milling efficiency.

[0023] 2. The present invention can be applied to edge milling of different materials and has strong versatility.

[0024] 3. When the present invention is milling the edge, the milling forces generated by the double milling cutter saw blades are offset, thereby avoiding the milling vibration effect of the tool during processing, and the edge of the skin is smoother after milling.

[0025] 3. The present invention has a compact structure and uses light and corrosion-resistant materials. The various components of the device are connected by screws. The screw head is rotated to pass through a matching hole and inserted into another hole through a 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a device for synchronously suppressing flutter deformation in double-knife conjugate milling of redundant edges of weak rigid skin proposed by the present invention;

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

[0029] Figure 3 is an analysis flow chart of the method of the present invention;

[0030] Figure 4 is a control flow chart of the device of the present invention;

[0031] Figures 5 to 7 Schematic diagram of the redundant edge processing effect of different materials.

[0032] Among them, the figure markings are: 1-device housing; 2-flange bearing I; 3-spur gear I; 4-flange bearing II; 5-saw blade milling cutter I; 6-milling cutter arbor I; 7-saw blade milling cutter II; 8-milling cutter arbor 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 DESCRIPTION

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0035] See attached Figure 1-2The present embodiment proposes a device for synchronously suppressing vibration deformation of double-knife conjugate milling of weak-rigidity skin 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 arbor I6, a saw blade milling cutter II7, a milling cutter arbor 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] Among them, the shell 1 includes a top plate 15, a C-shaped plate 16 and a bottom plate 17; the top plate is correspondingly arranged above the rear side of the bottom plate 17; the front side and the rear side of the top plate 15 and the bottom plate 17 are respectively connected by the C-shaped plate 16; the upper and lower ends of the C-shaped plate 16 are respectively fixedly connected to the top plate 15 and the bottom plate 17 by bolts, and circular holes corresponding to the milling cutter rod I6 and the milling cutter rod II8 are respectively opened on the upper and lower sides of the middle of the C-shaped plate 16.

[0037] The milling cutter rod I6 and the milling cutter rod II8 are respectively horizontally penetrated through the upper and lower sides of the middle of the two C-shaped plates 16, and the milling cutter rod I6 and the milling cutter rod II8 are aligned in the vertical direction and respectively pass through the round holes on the two C-shaped plates 16; the two sides of the milling cutter rod I6 are respectively connected to the corresponding rotating pairs of the upper round holes of the two C-shaped plates 16 through flange bearings I2 and flange bearings II4; the two sides of the milling cutter rod II8 are respectively connected to the rotating pairs of the lower round holes of the two C-shaped plates 16 through flange bearings III9 and flange bearings IV11; the middle part of the milling cutter rod I6 is coaxially fixed with a spur gear I3 by screws; the milling cutter A spur gear II10 is coaxially fixed to the middle part of the rod II8 by a screw; the spur gear I3 and the spur gear II10 are meshed with each other; the saw blade milling cutter I5 is coaxially fixed to the rear side of the milling cutter rod I; the saw blade milling cutter II7 is coaxially fixed to the rear side of the milling cutter rod II8; the saw blade milling cutter I5 and the saw blade milling cutter II7 are parallel to each other and their axial positions are staggered, and a very small distance is set between the disk surfaces 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 a motor bracket 14, and the output end of the brushless motor 13 is connected to the milling cutter rod II8 through a coupling 12.

[0038] In this embodiment, the saw blade milling cutter I5 and the saw blade milling cutter II7 are made of tungsten steel. Tungsten steel is a high-strength hard alloy 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 basically unchanged even at a temperature of 500°C, and still have a high hardness at 1000°C.

[0039] The double-blade conjugate saw blade milling cutter adopts a method of setting a very small spacing between the two milling cutters. During milling, due to the extremely small gap between the milling cutters, the saw blade milling cutter I5 and the saw blade milling cutter II7 can mill independently or simultaneously without interfering with each other, and offset the milling force. The weak rigid skin after processing can keep the edge neat, smooth and burr-free.

[0040] A method for synchronously suppressing flutter deformation in double-knife conjugate milling of redundant edges of weak rigid skin, the method specifically comprising the following steps:

[0041] S1, milling the surface of the weak rigid skin to be processed into a smooth surface;

[0042] S2, clamping the weak rigid skin to be processed after milling through a milling machine pressure plate;

[0043] The milling machine pressure plate device includes a double-headed screw, a nut with a washer, a pressure block, a T-shaped nut and a triangular block; the triangular block is provided with a number of small steps, and 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 means of the T-shaped nut, the double-headed screw and the nut with a washer, thereby fixing the weak rigid skin.

[0044] The rotation of the screw on the milling machine platen drives the movement of the upper and lower plates to clamp the weak rigid skin. After the clamping is completed, the above device is installed on the robot arm.

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

[0046] S4, after accurately calculating the data related to the saw blade milling cutter I5 and the saw blade milling cutter II7 and the weak rigid skin, start to accurately control the speed of the brushless motor 13 according to the relevant data; after determining the speed of the brushless motor 13, determine the feed speed provided by the robot arm according to the speed of the saw blade milling cutter I5 and the saw blade milling cutter II7 driven by the brushless motor 13;

[0047] S5. Since the feeding motion of the device of the present invention is realized by the linear motion of the robot arm, the weak rigid skin is placed between the two saw blade milling cutters, 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 and the linear feed motion of the edge of the weak rigidity skin to coordinately process the surface of the weak rigidity skin, so that the excess margin of the edge of the weak rigidity skin is removed under the action of the milling force;

[0049] S7, testing the chatter effect during milling, determining the cutting amount during the milling process, and testing the edge smoothness of the edge of the processed workpiece;

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

[0051] The double-blade conjugate saw blade milling adopted in the present invention is a new milling method. Conjugate refers to a pair matched according to a certain rule. In the present invention, double-blade conjugate refers to two saw blade milling cutters rotating and milling at the same speed, opposite directions, and symmetrically placed; when the two cutters contact and process the workpiece, the milling forces generated by the tools when processing the edge of the skin can offset each other, thereby avoiding the flutter effect.

[0052] The present invention will be further described below according to preferred embodiments:

[0053] A preliminary prototype experiment was conducted on the milling of the skin, and a Zhongjie GMC1225L CNC machine tool was used to drive the device for feed motion. The workpieces used in the experiment are pure copper, 2A12 aluminum alloy, and TC4 titanium alloy. First, a milling machine pressure plate is used to clamp the workpiece. The pressure plate device includes a double-headed screw, a nut with a washer, a pressure block, and a T-nut. Since the strength and hardness of copper are relatively low among the three workpieces, pure copper is first milled. The milling width is 6mm, the milling length is 100mm, and the copper thickness is about 0.2mm. Four groups of experiments were set up, and the rotation speed of the device and the machine tool feed speed are as follows:

[0054] Table 1 Device speed and feed speed when copper parts are milled

[0055]

[0056] Next, the 2A12 aluminum alloy was milled, with a milling length of 200 mm and a thickness of about 1 mm. Four groups of experiments were set up, with the device speed, machine tool feed speed, and milling width as follows:

[0057] Table 2 Device speed and feed speed when milling aluminum alloy

[0058]

[0059] Finally, the TC4 titanium alloy was milled, with a milling length of 200 mm and a thickness of about 0.8 mm. Two groups of experiments were set up, and the speed of the device, the feed speed of the machine tool, and the milling width were as follows:

[0060] Table 3 Device speed and feed speed when milling titanium alloy

[0061]

[0062] like Figure 5-7As shown, the double-blade conjugate milling edge processing proposed by the present invention can achieve a smooth cut surface, effectively suppress chatter during the processing, and there is no deformation of the strip-shaped redundant edges and workpieces after processing.

[0063] Matters not described in detail in the present invention are all known technologies.

[0064] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A synchronous suppression device for flutter deformation of double-knife conjugate milling of weak rigid skin with multiple redundant edges, characterized by: The device includes a housing, a flange bearing, a spur gear, a saw blade milling cutter, a milling cutter rod, a coupling and a brushless motor; the milling cutter rod is horizontally arranged on the upper and lower sides of the middle part of the housing and is vertically aligned; the two sides of the milling cutter rod are connected to the housing rotating pair through flange bearings; the middle part of the milling cutter rod is coaxially fixed with a spur gear, and the spur gears in the middle of the milling cutter rods on the upper and lower sides are meshed with each other; the saw blade milling cutters are coaxially fixed to the rear side of the milling cutter rod; the saw blade milling cutter on the rear side of the upper milling cutter rod and the saw blade milling cutter on the rear side of the lower milling cutter rod are parallel to each other and staggered in the axial direction, and a very small distance is set between the disk surfaces of the two saw blade milling cutters; the brushless motor is fixed at one end of the housing, and the output end of the brushless motor is connected to the lower milling cutter rod through a coupling.

2. According to claim 1, a device for synchronously suppressing flutter deformation in double-knife conjugate milling of weak rigid skin with multiple redundant edges, characterized in that: The saw blade milling cutter is made of tungsten steel.

3. The device for synchronously suppressing flutter deformation during double-knife conjugate milling of weak rigid skin with multiple redundant edges according to claim 1 is characterized in that: The shell includes a top plate, a bottom plate and a C-shaped plate; the top plate is correspondingly arranged 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 respectively; the upper and lower ends of the C-shaped plate are respectively fixed to the top plate and the bottom plate by bolts, and circular holes corresponding to the milling cutter rod are respectively opened on the upper and lower sides of the middle of the C-shaped plate.

4. The device for synchronously suppressing flutter deformation during double-knife conjugate milling of weak rigid skin with multiple redundant edges according to claim 1 is characterized in that: The spur gear is fixedly connected to the milling cutter rod through a screw.

5. The device for synchronously suppressing flutter deformation during double-knife conjugate milling of weak rigid skin with multiple redundant edges according to claim 2 is characterized in that: The brushless motor is fixed to the front end of the bottom plate through a motor bracket.

6. A method for synchronously suppressing flutter deformation in double-knife conjugate milling of multiple redundant edges of weak rigid skin, implemented by using the device described in any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1, milling the surface of the weak rigid skin to be processed into a smooth surface; S1. The weak rigid skin to be processed after milling is clamped by a milling machine pressure plate, wherein the rotation of the screw on the pressure plate drives the movement of the upper and lower pressure plates to achieve the clamping of the weak rigid skin. After the clamping is completed, the above device is installed on the robot arm; S3, controlling the speed range of the motor 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 large milling area; in order to maintain the stability of the device during milling, the speed of the motor is kept constant during milling; S4. After accurately calculating the data related to the saw blade milling cutter and the weak rigid skin, the motor speed is precisely controlled according to the relevant data; after determining the motor speed, the feed speed provided by the robot arm is determined according to the saw blade milling cutter speed driven by the motor; S5. Since the feeding motion of the device is realized by the linear motion of the robot arm, the weak rigid skin is placed between the two saw blade milling cutters, and the position of the weak rigid skin is adjusted so that it is placed in the working area and clamped; S6, starting the motor to drive the double saw blade milling cutter to work, controlling the conjugate milling motion of the saw blade milling cutter and the linear feed motion of the edge of the weak rigidity skin to coordinately process the surface of the weak rigidity skin, so that the excess margin of the edge of the weak rigidity skin is removed under the action of the milling force; S7, testing the chatter effect during milling, determining the cutting amount during the milling process, and testing the edge smoothness of the edge of the processed workpiece; S8. Repeat steps S5-S7 to carry out the next milling task.

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