A CNC milling method for deep through-groove cavities of annular hollow thin-walled parts

Abstract

The present invention belongs to the field of aviation precision manufacturing and processing technology, and in particular, it relates to a CNC milling method for deep through grooves of annular hollow thin-walled parts, including horizontally clamping the parts on a CNC machine tool workbench; selecting a U drill with a radius equal to the corner R of the deep through groove and installing it on the CNC machine, and using the U drill to process all the corners R in place; using an indexable milling cutter to rough mill the part groove, and reserving the side wall support margin and the groove bottom support margin; using an end mill I to perform layered processing on the part groove to mill the side wall support margin of the part groove; and an end mill II to mill the groove bottom support margin from the outside of the groove bottom of the part groove until the deep through groove is formed. This technical solution uses a layered processing method to ensure sufficient margin support during the processing of the side wall of the deep through groove, effectively overcomes the influence of stress changes and cutting forces in the part, improves the surface quality of the part, and plays an important role in reducing the subsequent benchwork and grinding workload.

Description

Technical Field

[0001] The present invention belongs to the field of aviation precision manufacturing and processing technology, and in particular relates to a CNC milling method for deep through-groove cavities of annular hollow thin-walled parts. Background Art

[0002] With the development of aviation technology, the performance indicators of modern aircraft such as maneuverability, flight performance, life and low manufacturing cost are constantly improving, which puts more and more stringent requirements on the structural characteristics of aircraft structural parts. Aviation structural parts have gradually developed in the direction of large-scale, integrated and thin-walled. In order to reduce the weight of aircraft, thin-walled structures are widely used in the design and manufacturing process of aircraft. Take the aircraft air inlet lip parts as an example, as shown in the attached figure. Figure 1 As shown in the figure, in order to meet the requirements of performance and lightweight, this type of parts generally adopts a thin-walled deep groove cavity structure design. The outer wall and inner wall of the lip of the part form an annular hollow thin-wall feature. The rear end face of the lip is connected to the front end of the aircraft air inlet, resulting in a through groove formed in the inner cavity of the lip. The overall wall thickness of the part is 2mm, the inner cavity angle of the part is R10, the groove depth is more than 200mm, the tool aspect ratio is more than 10 times, the structural rigidity is weak, the machining process stability is poor, and it is very easy to vibrate, causing part machining quality problems.

[0003] The processing technology of deep through groove cavities of hollow thin-walled parts has the following two major difficulties:

[0004] 1. When processing deep groove cavities, the tool is very likely to damage the parts due to changes in stress within the parts and the influence of cutting force. This results in a large workload for subsequent bench grinding, especially for the inner side, which is more difficult. In severe cases, the parts may be scrapped due to out-of-tolerance conditions.

[0005] 2. The tool aspect ratio is more than 10 times. A combined extended end mill with a cylindrical shank straight neck arbor and a replaceable Transformer milling head is used. The tool rigidity is poor, and parts and tools are prone to vibration. The cutting edge of a conventional end mill is more than 40 mm long. When the vibration reaches a certain level, the processed area of ​​the part will produce secondary cutting with the cutting edge, which will damage the processed surface of the part. Summary of the invention

[0006] The present invention aims to solve the above problems existing in the prior art and proposes a CNC milling method for deep groove cavities of annular hollow thin-walled parts, which is as follows:

[0007] A CNC milling method for a deep through groove cavity of an annular hollow thin-walled part comprises the following steps:

[0008] S1, using a tool to horizontally clamp the part on the workbench of a CNC machine tool, so that the part's position to be processed is completely exposed and in a processable state; wherein the horizontal clamping is to make the axial direction of the deep through groove cavity to be processed parallel to the workbench of the machine tool;

[0009] S2, according to the dimension information of the part design, select a U drill with the same radius as the corner R of the deep through groove cavity, and install the U drill on the CNC machine tool, and drill corner through holes at all corners R of the deep through groove cavity based on the deep hole drilling instruction programming in the CNC system, so that all corners R are processed in place;

[0010] S3, rough machining of the part groove cavity, that is, using an indexable milling cutter to rough mill the part groove cavity, and reserving side wall support margins and groove bottom support margins;

[0011] S4, finishing of the part cavity, i.e. using end mill I to start from any corner through hole, and performing layered processing on the part cavity to mill the side wall support margin of the part cavity;

[0012] S5, controls the CNC machine tool worktable to rotate 180°, so that the part rotates 180° synchronously, and uses the end mill II to mill the groove bottom support margin from the outside of the part groove bottom until the deep through groove is formed.

[0013] Preferably, in step S3, the side wall support margin and the groove bottom support margin are both 6 mm.

[0014] Preferably, in step S4, layered processing of the part cavity includes the following steps:

[0015] S41, axially layering the part groove cavity according to the axial size of the part groove cavity to divide it into a plurality of axial layers;

[0016] S42, according to the division result of the axial layer, each axial layer is processed in sequence from shallow to deep along the axial direction of the part groove cavity.

[0017] Preferably, in step S42, each axial layer is processed in layers using a radial three-knife method, wherein the first knife reserves a 1 mm support margin radially, the second knife reserves a 0.2 mm support margin, and the third knife processes the current axial layer in place.

[0018] Preferably, the end mill I used in step S4 is a customized end mill, including a cutting section, a clearance section and a clamping section that are coaxially arranged and fixedly connected in sequence, and the cutting section is composed of a cutting edge and a polished rod supporting cylinder; wherein, the length L of the end mill I is 280 mm, the length L1 of the cutting edge is 4 mm to 6 mm, the length L2 of the polished rod supporting cylinder is 5 mm to 8 mm, the diameter D1 of the cutting section is 20 mm, the diameter D2 of the clearance section is D1-0.6 mm, the diameter D of the clamping section is 20 mm, and the length L3 of the clamping section satisfies 3*D1≤L3≤4*D1. Further, the total length L of the end mill I is 280 mm.

[0019] Preferably, in step S41, the depth of the axial layer H≤0.6* L1.

[0020] Preferably, in step S4, when the part groove cavity is processed in layers, the speed of the end mill I is Vc=120m / min, and the feed rate per tooth is fz=0.03mm / z.

[0021] Preferably, in step S5, milling the groove bottom support margin includes the following steps:

[0022] S51, selecting the corner through hole with the highest relative position among all the corner through holes corresponding to the deep through groove cavity to be processed, using end mill II to vertically cut from the center of the selected corner through hole, adopting a radial no allowance and axial layered processing method to mill a linear through hole along the upper edge of the part groove cavity;

[0023] S52, on the premise of reserving 0.2mm groove bottom side wall margin in radial direction of the part groove cavity, according to the groove bottom structure of the part groove cavity, start cutting from the straight through hole, set the serpentine tool path, and cut off the groove bottom surplus of the part groove cavity in one cut along the serpentine tool path;

[0024] S53, using end mill II to mill along the remaining edges of the part groove cavity except the upper edge, so as to mill off the radial 0.2mm groove bottom side wall margin of the part groove cavity reserved in step S52, that is, to complete the fine machining of the groove bottom of the part groove cavity and form the final deep through groove cavity.

[0025] Preferably, in the axial layering in step S51, the axial thickness h of the last layer is 1.8 mm to 2 mm, and the axial thicknesses of the remaining layers except the last layer are 1.2 mm to 1.5 mm.

[0026] Beneficial effects of the present invention:

[0027] 1) This technical solution provides a CNC milling method specifically for the processing of deep through grooves of annular hollow thin-walled parts. Among them, the parts are clamped horizontally to facilitate chip removal during the processing; the U drill with the same radius as the corner R of the deep through groove is used to complete the corner R processing, which can prevent the cutting tool from cutting the parts due to excessive cutting envelope angle at the corner; the part is firstly rough-machined, and the side wall support / bottom support margin is reserved to avoid deformation of the side wall of the part, that is, on the premise of ensuring the integrity of the side wall structure, the excess material is quickly removed to improve the processing efficiency; then the side wall support margin is removed by layered processing to ensure that the part has sufficient margin support during the processing, improve the rigidity of the part during the processing, and improve the surface quality of the part. During this period, the bottom support margin is reserved to effectively avoid the concave part. To sum up, in the process of processing deep through groove cavities, this technical solution quickly removes excess material while ensuring the integrity of the side wall structure by reserving side wall support / groove bottom support margins, thereby improving processing efficiency. In addition, a layered processing method is used to ensure sufficient margin support during the processing of the side walls of the deep through groove cavities, effectively overcoming the influence of stress changes and cutting forces within the parts, improving the surface quality of the parts, and avoiding the problem of out-of-tolerance scrapping of parts to the greatest extent, and playing an important role in reducing the subsequent workload of benchwork and grinding.

[0028] 2) This technical solution uses a customized milling cutter in the process of fine machining of the part groove cavity. The milling cutter includes a cutting section, a clearance section and a clamping section that are coaxially arranged and fixedly connected in sequence. Among them, the cutting section is composed of a cutting edge and a polished rod support cylinder. During the part machining process, the polished rod support cylinder can support the cutting edge, effectively preventing the cutting edge from scratching the part surface, and further reducing the subsequent benchwork grinding workload. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The schematic diagram of the front structure of the part after deep through-groove processing;

[0030] Figure 2 This is a schematic diagram of the parts clamping structure;

[0031] Figure 3 It is the structural schematic diagram of end mill I;

[0032] Figure 4 It is a schematic diagram of the comparison structure of the three-knife trajectory of the radial three-knife method;

[0033] Figure 5 It is a schematic diagram of the machining trajectory structure of the linear through slot;

[0034] Figure 6 for Figure 5 Schematic diagram of the cross-sectional structure along the AA direction;

[0035] Figure 7 This is a schematic diagram of the milling trajectory of the residual material at the bottom of the groove;

[0036] Figure 8 This is the basic implementation flow chart of this technical solution;

[0037] In the figure:

[0038] 1. Part groove cavity; 2. Groove bottom; 3. Position to be processed; 4. Deep through groove cavity; 5. Tooling; 6. Part process boss; 7. Corner through hole; 8. End mill I; 8.1. Air avoidance section; 8.2. Clamping section; 8.3. Cutting edge; 8.4. Polish rod supporting cylinder; 9. End mill II; 10. First cut; 11. Second cut; 12. Third cut; 13. Linear tool path; 14. Linear through hole; 15. Serpentine tool path. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0040] Therefore, the following detailed description of the invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment discloses a CNC milling method for deep through-groove cavities of annular hollow thin-walled parts, as a preferred embodiment of the present invention, to process Figure 1 Taking the deep through groove cavity of the part shown as an example, the following steps are included:

[0043] S1, such as Figure 2 As shown, the part is horizontally clamped on the workbench of the CNC machine tool by using a tooling so that the position of the part to be processed is completely exposed and in a processable state; wherein, the horizontal clamping is to make the axial direction of the deep through groove cavity to be processed parallel to the machine tool workbench, which can facilitate chip removal during the process of processing the part.

[0044] S2. Since the side walls of the finished products of this type of parts are very thin, milling may generate radial forces that cause deformation of the side walls, while U-drilling generates axial forces. Based on this, according to the dimensional information of the part design (all dimensional information of the part will be recorded during the composition design), a U-drill with a radius equal to the corner R of the deep through groove cavity is selected, and the U-drill is installed on the CNC machine tool. At all corners R of the deep through groove cavity, the corner through holes are drilled based on the deep hole drilling instructions in the CNC system, and all corners R are processed in place. This prevents the cutting tool (specifically end mill I and end mill II used in later processing) from having too large a cutting envelope angle at the corner, which causes the cutting tool to pull the tool and cut the part.

[0045] S3, the deep through groove processing of parts requires a lot of material to be removed, the milling tool has a large workload and wear and tear, so the part groove is rough processed first, that is, the part groove is rough milled with an indexable milling cutter. An indexable milling cutter is a toothed milling cutter with an indexable blade. The worn blade can be disassembled and replaced, which can save processing costs. In addition, since the side wall of the finished part is thin (generally only 2mm), and the deep through groove structure size (processing area) is large, during the rough processing of the part groove, a slight improper operation may cause the side wall of the part to be concave. Therefore, during the rough processing of the part groove, reserve the side wall support margin and the groove bottom support margin.

[0046] Among them, the reserved side wall support allowance is a certain thickness of material reserved on the side wall of the part. Preferably, a 6mm side wall support allowance is reserved, that is, if the side wall thickness of the finished part is 2mm, then after rough processing of the part groove cavity, the side wall thickness of the part is 8mm.

[0047] In addition, a groove bottom support allowance is reserved, that is, a part groove cavity is temporarily processed on the part (a deep through groove cavity is not penetrated), and a certain thickness of material is reserved at the axial bottom of the part groove cavity as the groove bottom. Preferably, a groove bottom support allowance of 6 mm is reserved, that is, a 6 mm thick groove bottom is reserved.

[0048] S4, finishing of the part groove cavity, that is, using end mill I to start from any corner through hole, and layering processing of the part groove cavity to mill the side wall support allowance of the part groove cavity.

[0049] S5, controls the CNC machine tool table to rotate 180°, so that the parts rotate 180° synchronously, such as Figure 2 As shown, based on the XYZ coordinate system, rotate 180° around the Y axis in the B direction. Then use the end mill II to mill the groove bottom support allowance from the outside of the groove bottom of the part until the deep through groove is formed.

[0050] Example 2

[0051] This embodiment discloses a CNC milling method for a deep through groove cavity of an annular hollow thin-walled part, which, as a preferred embodiment of the present invention, comprises the following steps:

[0052] S1, using a tool to horizontally clamp the part on the workbench of a CNC machine tool, so that the part's position to be processed is completely exposed and in a processable state; wherein the horizontal clamping is to make the axial direction of the deep through groove cavity to be processed parallel to the workbench of the machine tool;

[0053] S2, according to the dimension information of the part design, select a U drill with the same radius as the corner R of the deep through groove cavity, and install the U drill on the CNC machine tool, and drill corner through holes at all corners R of the deep through groove cavity based on the deep hole drilling instruction programming in the CNC system, so that all corners R are processed in place;

[0054] S3, rough machining of the part groove cavity, that is, using an indexable milling cutter to rough mill the part groove cavity, and reserving side wall support margins and groove bottom support margins;

[0055] S4, finishing of the part groove cavity, i.e. using end mill I to start from any corner through hole, layered processing of the part groove cavity is performed to mill the side wall support margin of the part groove cavity; wherein, layered processing of the part groove cavity includes the following steps:

[0056] S41, axially layering the part groove cavity according to the axial size of the part groove cavity to divide it into a plurality of axial layers;

[0057] S42, according to the division result of the axial layer, each axial layer is processed in place from shallow to deep along the axial direction of the part groove cavity. Specifically, each axial layer is processed in layers using the radial three-knife method, wherein the first knife reserves a 1mm support margin in the radial direction, the second knife reserves a 0.2mm support margin, and the third knife processes the current axial layer in place.

[0058] Furthermore, in actual situations, UG NX software can be used for CAM programming to complete the layered processing of the part slot cavity, including the following steps: 1) Create a plane profile milling (PLANAR_PROFILE) processing operation; 2) Create a processing tool, including setting tool parameters; 3) Set the processing coordinate system; 4) Set the programming parameters, specify the "contour curve of the processed groove" as the component boundary, specify the bottom surface of the part, the tool axis is "perpendicular to the bottom surface", the cutting mode is "contour", and the step distance is "multiple" - respectively, the number of tool paths "1", the distance "1", the number of tool paths "1", the distance "0.2", and the tool path trajectory is as follows Figure 4 As shown; 5) Set cutting parameters: cutting order is "layer priority", linear speed Vc=120m / min, feed per tooth fz=0.03mm / z.

[0059] In this technical solution, the radial three-knife method is used to achieve high-precision processing of the side wall of the part. When the axial layer is processed on the front end axial layer, the next layer has enough margin to support the side wall of the part and ensure the rigidity of the part.

[0060] Furthermore, in order to prevent vibration during machining and the tool from scratching the surface of the part, the end mill I used for layered machining of the part groove is a customized end mill, such as Figure 3 As shown, it includes a cutting section, an avoidance section and a clamping section that are coaxially arranged and fixedly connected in sequence. The cutting section is composed of a cutting edge and a polished rod support cylinder. When the end mill I vibrates, the polished rod support cylinder can support the cutting edge to prevent the cutting edge from scratching the surface of the part. Among them, the length of the cutting edge L1 = 4mm ~ 6mm, the length of the polished rod support cylinder L2 = 5mm ~ 8mm; the diameter of the polished rod support cylinder is the same as the diameter of the cutting edge. Specifically, the diameter of the cutting section D1 = 20mm; the diameter of the avoidance section D2 = D1-0.6mm; the diameter of the clamping section D = 20mm, and the length L3 of the clamping section satisfies 3*D1≤L3≤4*D1. Furthermore, the total length of the end mill I is 280mm.

[0061] Furthermore, based on the structure of the above-mentioned end mill I, in the above-mentioned step S41, the depth of the axial layer H≤0.6*L1, so as to avoid excessive internal tension of the part after the axial layer, which may cause deformation of the side wall of the part.

[0062] S5, controls the CNC machine tool worktable to rotate 180°, so that the part rotates 180° synchronously, and uses the end mill II to mill the groove bottom support margin from the outside of the part groove bottom until the deep through groove is formed.

[0063] Example 3

[0064] This embodiment discloses a CNC milling method for a deep through groove cavity of an annular hollow thin-walled part, which, as a preferred embodiment of the present invention, comprises the following steps:

[0065] S1, using a tool to horizontally clamp the part on the workbench of a CNC machine tool, so that the part's position to be processed is completely exposed and in a processable state; wherein the horizontal clamping is to make the axial direction of the deep through groove cavity to be processed parallel to the workbench of the machine tool;

[0066] S2, according to the dimension information of the part design, select a U drill with the same radius as the corner R of the deep through groove cavity, and install the U drill on the CNC machine tool, and drill corner through holes at all corners R of the deep through groove cavity based on the deep hole drilling instruction programming in the CNC system, so that all corners R are processed in place;

[0067] S3, rough machining of the part groove cavity, that is, using an indexable milling cutter to rough mill the part groove cavity, and reserving side wall support margins and groove bottom support margins;

[0068] S4, finishing of the part cavity, i.e. using end mill I to start from any corner through hole, and performing layered processing on the part cavity to mill the side wall support margin of the part cavity;

[0069] S5, control the CNC machine tool table to rotate 180°, so that the part rotates 180° synchronously, and use the end mill II to mill the groove bottom support margin from the outside of the part groove bottom until the deep through groove cavity is formed. Among them, considering that the side wall thickness of the finished part is generally only 2mm, and the opening size of the inner cavity (deep through groove cavity) is large, the conventional tool path cuts from the center to the surrounding area, and the part is processed to the size. The part becomes a hollow special-shaped ring body with extremely poor structural rigidity. It is very easy to vibrate during processing, and the tool will gnaw the surface of the part. To this end, an end mill II with a diameter d of 8mm is used to cut through the part step by step and process it to the final size. Specifically, the following steps are included:

[0070] S51, first process the upper end of the part with the weakest rigidity (based on the upper end corresponding to the horizontal clamping posture), and only process one linear through hole to ensure that when processing the upper end with the weakest rigidity, there is material at the lower end of the part to support the part and improve the rigidity of the part. Specifically, Figure 5 As shown, the corner through hole with the highest relative position among all the corner through holes corresponding to the deep through groove cavity to be processed is selected, and the end mill II is used to cut vertically from the center of the selected corner through hole, and a linear through hole is milled along the upper edge of the part groove cavity by adopting the method of radial no allowance and axial layered processing. Among them, the so-called radial no allowance means that the radial structure of the linear through hole is formed in one cut, the width of the linear through hole is consistent with the end mill II, and the upper side wall of the linear through hole just falls on the final side wall of the part. In addition, in order to overcome the problem that the cutting envelope angle of the corner through hole is too large, causing the cutting tool to pull and cut the part, the thickness of the axial layer is 1.2mm~1.5mm, but because the cutting depth of the last layer is too large or too small, it is easy to cause the tool to bounce and pull, affecting the surface quality of the product. Preferably, the axial thickness h of the last layer is 1.8mm~2mm.

[0071] S52, after processing the linear through hole, since the upper end (in the radial direction) of the deep through groove of the part has been cut through, the existing CAM software roughing cutting mode (follow the component, follow the periphery, etc.) cannot realize the ideal tool path trajectory by gradually processing downward from the processed position of the part. Therefore, according to the structural characteristics of the part, a regular tool path is formed by a custom curve, that is, under the premise of reserving a 0.2mm groove bottom side wall margin in the radial direction of the part groove, according to the groove bottom structure of the part groove, start cutting from the straight through hole, and set as follows Figure 7 The serpentine tool path is shown, and the excess material at the bottom of the part groove cavity is cut off in one go along the serpentine tool path.

[0072] S53, using end mill II to mill along the remaining edges of the part groove cavity except the upper edge, so as to mill off the radial 0.2mm groove bottom side wall margin of the part groove cavity reserved in step S52, that is, to complete the fine machining of the groove bottom of the part groove cavity and form the final deep through groove cavity.

Claims

1. A CNC milling method for deep through-groove cavities of annular hollow thin-walled parts, characterized in that: The following steps are involved: S1, using a tool to horizontally clamp the part on the workbench of a CNC machine tool, so that the part's position to be processed is completely exposed and in a processable state; wherein the horizontal clamping is to make the axial direction of the deep through groove cavity to be processed parallel to the workbench of the machine tool; S2, according to the dimension information of the part design, select a U drill with the same radius as the corner R of the deep through groove cavity, and install the U drill on the CNC machine tool, and drill corner through holes at all corners R of the deep through groove cavity based on the deep hole drilling instruction programming in the CNC system, so that all corners R are processed in place; S3, rough machining of the part groove cavity, that is, using an indexable milling cutter to rough mill the part groove cavity, and reserving side wall support margins and groove bottom support margins; S4, finishing of the part cavity, i.e. using end mill I to start from any corner through hole, and performing layered processing on the part cavity to mill the side wall support margin of the part cavity; S5, controlling the CNC machine tool worktable to rotate 180°, so that the part rotates 180° synchronously, and using the end mill II to mill the groove bottom support margin from the outside of the groove bottom of the part until the deep through groove is formed; milling the groove bottom support margin includes the following steps: S51, selecting the corner through hole with the highest relative position among all the corner through holes corresponding to the deep through groove cavity to be processed, using end mill II to vertically cut from the center of the selected corner through hole, adopting the method of radial no allowance and axial layered processing, milling a linear through hole along the upper edge of the part groove cavity; in the axial layering, the axial thickness h of the last layer is 1.8mm-2mm, and the axial thickness of the remaining layers except the last layer is 1.2mm-1.5mm; S52, on the premise of reserving 0.2mm groove bottom side wall margin in radial direction of the part groove cavity, according to the groove bottom structure of the part groove cavity, start cutting from the straight through hole, set the serpentine tool path, and cut off the groove bottom surplus of the part groove cavity in one cut along the serpentine tool path; S53, using end mill II to mill along the remaining edges of the part groove cavity except the upper edge, so as to mill off the radial 0.2mm groove bottom side wall margin of the part groove cavity reserved in step S52, that is, to complete the fine machining of the groove bottom of the part groove cavity and form the final deep through groove cavity.

2. A CNC milling method for deep through-grooves of annular hollow thin-walled parts as claimed in claim 1, characterized in that: In step S3, the side wall support margin and the groove bottom support margin are both 6 mm.

3. A CNC milling method for deep through-groove cavities of annular hollow thin-walled parts as claimed in claim 1, characterized in that: In step S4, the layered processing of the part cavity includes the following steps: S41, axially layering the part groove cavity according to the axial size of the part groove cavity to divide it into a plurality of axial layers; S42, according to the division result of the axial layer, each axial layer is processed in sequence from shallow to deep along the axial direction of the part groove cavity.

4. A CNC milling method for deep through-grooves of annular hollow thin-walled parts as claimed in claim 3, characterized in that: In step S42, each axial layer is processed in layers using a radial three-knife method, wherein the first knife reserves a 1 mm support margin in the radial direction, the second knife reserves a 0.2 mm support margin, and the third knife processes the current axial layer in place.

5. A CNC milling method for deep through-groove cavities of annular hollow thin-walled parts as claimed in claim 3, characterized in that: The end mill I used in step S4 is a customized end mill, including a cutting section, a clearance section and a clamping section that are coaxially arranged and fixedly connected in sequence, and the cutting section consists of a cutting edge and a polished rod supporting cylinder; wherein, the length of the cutting edge L1=4mm~6mm, the length of the polished rod supporting cylinder L2=5mm~8mm, the diameter of the cutting section D1=20mm, the diameter of the clearance section D2=D1-0.6mm, the diameter of the clamping section D=20mm, and the length L3 of the clamping section satisfies 3*D1≤L3≤4*D1.

6. A CNC milling method for deep through-grooves of annular hollow thin-walled parts as claimed in claim 5, characterized in that: In the step S41, the depth of the axial layer H≤0.6* L1.

7. A CNC milling method for deep through-grooves of annular hollow thin-walled parts as claimed in claim 1, characterized in that: In step S4, when the part groove cavity is processed in layers, the speed of the end mill I is Vc=120m / min, and the feed per tooth fz=0.03mm / z.

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