A milling tool for machining an annular groove offset from the centre of rotation of a part

Abstract

The application provides a milling tool for processing an annular groove deviated from the rotation center of a part, which comprises an inner circular-arc groove milling cutter and an outer circular-arc groove milling cutter, and is used for processing the inner circular-arc groove and the outer circular-arc groove of the annular groove respectively. The big end of the cutter body of the inner circular-arc groove milling cutter is conical, a center blind hole is arranged, a flange is radially extended on the outer edge of the end face, and a blade with the same cross-sectional shape as the inner circular-arc groove is fixed on the flange. The big end of the cutter body of the outer circular-arc groove milling cutter is columnar, a center blind hole is arranged, a flange is radially arranged on the inner edge of the end face, and a blade with the same cross-sectional shape as the outer circular-arc groove is fixed on the flange. During processing, the inner circular-arc groove milling cutter and the outer circular-arc groove milling cutter are fixed on the spindle of a three-axis vertical numerical control milling machine through an ER spring clamp, and the processing of the inner circular-arc groove and the outer circular-arc groove can be completed by only one clamping and cutting, so that the processing efficiency and the processing precision are greatly improved. The application has strong universality, and can realize the milling processing of the outer cylindrical annular groove and the inner hole annular groove with different cross-sectional shapes and different eccentric distances.

Description

Technical Field

[0001] This invention belongs to the field of cutting tool technology, specifically relating to a milling tool for machining grooves that are off-center from the rotation center of a part. Background Technology

[0002] In the field of machining, annular grooves within the cavities of rotating parts are a common structure. (Refer to...) Figures 1-6 A rotating part has a complex semi-open cavity structure at one end. The end face of this cavity structure has two annular grooves within an arc-shaped boss. The centers of these two annular grooves are located at the same position, a certain distance away from the rotation center of the part, and are situated on opposite sides of the rotation center. These two annular grooves also contain radially inclining arc grooves R1 and R2, as well as axially inclining arc grooves h1 and h2. One annular groove is similar to an inner arc groove, and the other is similar to an outer arc groove. The surface roughness of both annular grooves is Ra0.8, requiring high precision.

[0003] The common machining method is to use a conventional lathe or a CNC lathe for turning. The specific process is as follows:

[0004] 1. Design and manufacture a special eccentric lathe fixture to clamp the workpiece and ensure that the rotation center of the annular groove is concentric with the rotation center of the lathe spindle.

[0005] 2. When machining the arc grooves at both ends of a part, the machining method is similar, and the machining is completed in two turning operations; the same tools are used, one is a standard grooving tool, and the other is a special grooving tool with axial cutting capability.

[0006] Step 1: Machining the inner arc groove. Place the grooving tool inside the semi-open cavity at one end of the part, rotate the lathe clockwise, first use a standard grooving tool to machine the radial groove, and then use a special grooving tool to machine the axial groove.

[0007] Step 2: Machining the outer circular arc groove. Place the grooving tool outside the semi-open cavity at one end of the part, reverse the lathe, first use a standard grooving tool to machine the radial groove, and then use a special grooving tool to machine the axial groove.

[0008] 3. Fitter files the annular groove. Since the radial and axial grooves are machined in two steps, protrusions or cuts are inevitable at the tool joint. The fitter files the tool joint; the fitter polishes the annular groove to ensure the surface roughness requirements of the part are met.

[0009] The disadvantages of the above processing method are: 1. Due to the centrifugal effect of the eccentric fixture and the poor rigidity of the single-edged tool, the rotation speed cannot be too high, resulting in low processing efficiency; 2. The low linear speed, poor tool rigidity, and vibration of intermittent cutting cause the surface roughness of the annular groove to fail to meet the requirement of Ra0.8, requiring manual filing and polishing in the later stage, resulting in poor product quality consistency; 3. Assembly errors of the fixture positioning elements and matching errors with the equipment result in the groove center position accuracy failing to meet the design requirements, resulting in low processing accuracy; 4. During forward and reverse turning operations, high skill requirements are placed on the operators, and accidental operational errors can lead to tool scrap, fixture damage, or failure of the entire process system. Summary of the Invention

[0010] To address the problems of complex processes, low efficiency, and poor accuracy in existing machining methods, this invention provides a milling tool for machining annular grooves that are off-center from the center of rotation of a part. Using this tool, annular grooves can be milled on a three-axis vertical machining center, aiming to solve the problems of low machining efficiency, unstable machining quality, and poor operational safety in existing annular groove machining technologies.

[0011] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0012] A milling cutter for machining annular grooves offset from the rotation center of a part, the annular groove including an inner circular arc groove 101 and an outer circular arc groove 102, respectively located inside the end face circular arc bosses on both sides of the semi-open cavity structure of the rotating part, the axial and radial dimensions of the end face circular arc bosses where the inner circular arc groove is located are the same as those of the end face circular arc bosses where the outer circular arc groove is located, and the arc length of the end face circular arc bosses where the outer circular arc groove is located is less than the length of the end face circular arc bosses where the inner circular arc groove is located; characterized in that the milling cutter includes an inner circular arc groove milling cutter 2 and an outer circular arc groove milling cutter 3;

[0013] The internal arc groove milling cutter 2 includes a first cutter body 201 and a first insert 202. The first cutter body 201 is a stepped shaft shape with a conical large end. Multiple radially extending first flanges 20103 are evenly distributed on the edge of the end face. The first flanges are toothed. A blind hole is opened axially in the middle of the large end of the first cutter body. The blind hole can accommodate one side of the semi-open cavity structure at the end of the part and can make the first flange located in the internal arc groove machining position on the other side wall. The small end of the first cutter body is used to be fixedly connected to the spindle of a three-axis vertical CNC milling machine.

[0014] The first blade 202 is bent, and its shape and bending angle are the same as the inner arc groove to be processed. The outer diameter of the first blade is equal to the diameter of the inner arc groove. Multiple first blades 202 are respectively fixed on the top of the first flange of the first blade body 201. One side wall of the first blade is flush with one side wall of the first flange. The inner surface of the first blade is in contact with the first flange. The cutting edge of the first blade protrudes from the first flange in the axial direction.

[0015] The external arc groove milling cutter 3 includes a second cutter body 301 and a second insert 302; the second cutter body 301 is a stepped shaft shape, with a blind hole in the middle of the large end along the axial direction, and a plurality of second flanges 30103 are radially provided on the inner end face of the blind hole. The blind hole can accommodate one side wall of the semi-open cavity structure at the end of the part and can make the second flanges located at the external arc groove machining position on the side wall. The small end of the second cutter body is used to be fixedly connected to the spindle of a three-axis vertical CNC milling machine.

[0016] The second blade 302 is bent, and its shape and bending angle are the same as the outer arc groove to be processed. The inscribed circle diameter of the second blade is the same as the diameter of the outer arc groove. Multiple second blades 302 are respectively fixed on the top of the second flange of the second blade body 301. One side wall of the second blade is flush with the side wall of the second flange. The inner surface of the second blade is in contact with the second flange. The cutting edge of the second blade protrudes from the second flange in the axial direction.

[0017] Furthermore, the thickness of the first blade 202 and the second blade 301 is 4-6 mm.

[0018] Furthermore, the first blade 202 is welded and fixed to the first flange end face of the first blade body; the second blade 302 is welded and fixed to the second flange end face of the second blade body.

[0019] Furthermore, the small end of the first cutter body 201 and the small end of the second cutter body 301 are respectively fixed to the spindle of the three-axis vertical CNC milling machine via ER spring collets.

[0020] Furthermore, along the tool axis, the cutting edge portions of the first and second inserts protrude 2mm beyond the first and second flanges, respectively.

[0021] Furthermore, the diameter and depth of the blind holes at the large ends of the first cutter body 201 and the second cutter body 301 are determined according to the following dimensions:

[0022] The minimum limit diameter of a blind hole is equal to the diameter d1 of the circumcircle formed by the circular arc boss on the end face where the outer circular arc groove is located;

[0023] The minimum diameter of the blind hole is equal to the diameter d2 of the inscribed circle formed by the circumscribed circle of the outer arc groove at the end face of the circular arc boss at the tool rotation center.

[0024] The diameter of the blind hole is equal to the sum of the minimum diameter and the machining interpolation amount, wherein the machining interpolation amount is 5mm to 10mm;

[0025] The depth of the blind hole is equal to the sum of the maximum distance b from the sidewall of the annular groove to the end face arc boss and the clearance dimension, wherein the clearance dimension is 5mm to 10mm.

[0026] Furthermore, both the first blade body 201 and the second blade body 301 are alloy structural steel blade bodies, and both the first blade 202 and the second blade 302 are cemented carbide blades.

[0027] Furthermore, process holes are provided along the axis at the bottom of the blind holes at the large end of the first cutter body 201 and the large end of the second cutter body 301.

[0028] The advantages of this invention are:

[0029] 1. The cutting tools of this invention include an inner arc groove milling cutter and an outer arc groove milling cutter. Using the cutting tools of this invention, the inner arc groove and the outer arc groove that are off-center from the rotation center of the part and have both radial and axial cutting can be machined on a three-axis vertical machining center. Only one cutting tool is needed to complete each part. The original machining method takes 2 hours to machine one workpiece, while the machining time of one workpiece using the cutting tools of this invention is only 0.6 hours, which is extremely efficient.

[0030] 2. When machining with the tool of this invention, the inner and outer end teeth and the peripheral teeth of the tool participate in cutting simultaneously. The eccentric distance of the annular groove can be precisely controlled by the X-axis or Y-axis coordinates. The cross-sectional shape and arc radius of the annular groove are controlled by the tool shape and radial dimension. The machining quality is greatly improved, eliminating the protrusions or cuts that occur when using two tools to machine radial and axial grooves separately in existing machining processes, thus improving the machining accuracy of the groove.

[0031] 3. The tool of the present invention is designed with a cavity structure. During machining, the side wall of the semi-open cavity structure at the end of the part can be hidden in the blind hole inside the tool to achieve eccentricity. At the same time, it has a radial feed function within a certain range to realize interpolation milling.

[0032] 4. In this invention, the inner arc groove end mill is a six-flute tool and the outer arc groove end mill is a four-flute tool, which greatly improves the machining linear speed, the high-speed rotation of the tool and the high rigidity of the process system, and overcomes the problem of low surface roughness caused by centrifugal force and vibration in the prior art.

[0033] 5. In the processing of this invention, the direction of motion is precisely controlled by a CNC program, which greatly reduces the safety hazards and damage to the process system that may be caused by human factors.

[0034] 6. The cutting tool provided by this invention is used with an ER spring collet, which ensures reliable tool clamping and high clamping accuracy.

[0035] 7. In this invention, parts are positioned and clamped by a self-centering three-jaw chuck, eliminating the need to manufacture dedicated eccentric lathe fixtures. The cost of dedicated eccentric lathe fixtures used in the original machining method is 15,000 yuan per set, while the machining process of this invention does not require dedicated tooling, saving tooling costs and greatly improving the economic efficiency of parts machining.

[0036] 8. The cutting tool of the present invention is versatile and has a wide range of applications. It is not limited by the parts being processed or the production conditions. By changing the tool structure size and the shape of the insert, and adjusting the CNC program, milling of outer cylindrical annular grooves and inner hole annular grooves with different cross-sectional shapes and different eccentric distances can be achieved. Attached Figure Description

[0037] Figure 1 It is a three-dimensional model of the part being processed;

[0038] Figure 2 This is the front view of the part being machined;

[0039] Figure 3 This is the left view of the part being machined;

[0040] Figure 4 This is the AA section view of the part being machined;

[0041] Figure 5 This is a magnified view of the first annular groove in the machined part;

[0042] Figure 6 This is a magnified view of the second annular groove in the machined part;

[0043] Figure 7 This is a 3D schematic diagram of an internal circular groove milling cutter;

[0044] Figure 8 This is a three-dimensional schematic diagram of the first cutter body of the internal circular arc groove end mill;

[0045] Figure 9 This is the front view of an internal arc groove end mill;

[0046] Figure 10 This is the left view of an internal circular groove end mill;

[0047] Figure 11 This is a 3D schematic diagram of an external circular arc groove milling cutter;

[0048] Figure 12 This is the front view of an external circular arc groove milling cutter;

[0049] Figure 13 This is the left view of an external circular arc groove milling cutter;

[0050] Figure 14 This is a schematic diagram of the machining process for the inner circular arc groove;

[0051] Figure 15 This is a schematic diagram of the machining process for an outer circular arc groove.

[0052] In the diagram: 1-Workpiece to be machined; 101-Inner arc groove; 102-Outer arc groove; 2-Inner arc groove end mill; 201-First cutter body; 20101-First cutter shank; 20102-First cutter head; 20103-First flange; 202-First insert; 20201-Inner side of the first insert; 20202-Outer side of the first insert; 3-Outer arc groove end mill; 301-Second cutter body; 30101-Second cutter shank; 30102-Second cutter head Head; 30103 - Second flange; 302 - Second insert; 30201 - Inner side of the second insert; 30202 - Outer side of the second insert; a - Maximum radial dimension of the semi-open cavity structure end face arc boss; b - Maximum distance from the sidewall of the annular groove to the end face arc boss; d1 - Diameter of the circumscribed circle formed by the end face arc boss where the outer arc groove is located; d2 - Diameter of the inscribed circle formed by the circumscribed circle of the end face arc boss where the outer arc groove is located at the tool rotation center. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0054] Reference Figures 1-15 The part to be processed is a rotating body with a semi-open cavity structure at the end. Two arc-shaped bosses are provided on both sides of the semi-open cavity structure. Annular grooves are formed on the arc-shaped bosses, including an inner arc groove 101 and an outer arc groove 102, located inside the arc-shaped bosses on both sides of the semi-open cavity structure of the rotating body part. The axial and radial dimensions of the arc-shaped boss containing the inner arc groove are the same as those of the arc-shaped boss containing the outer arc groove. The arc length of the arc-shaped boss containing the outer arc groove is less than the length of the arc-shaped boss containing the inner arc groove.

[0055] To achieve the machining of the annular groove, the present invention provides a milling cutter for machining annular grooves that are off-center from the rotation center of the part, including an inner arc groove milling cutter 2 and an outer arc groove milling cutter 3.

[0056] The inner arc groove milling cutter 2 includes a first cutter body 201 and a first insert 202. The first cutter body 201 is a stepped shaft shape with a conical shape at the large end. Multiple radially extending first flanges are evenly distributed on the edge of the end face. The first flanges are toothed. A blind hole is opened in the middle of the large end of the first cutter body along the axial direction. The blind hole can accommodate one side of the semi-open cavity structure at the end of the part and can make the first flange located at the inner arc groove machining position on the other side wall. The small end of the first cutter body is used to be fixedly connected to the spindle of a three-axis vertical CNC milling machine.

[0057] The first blade 202 is bent, and its shape and bending angle are the same as the inner arc groove to be processed. The outer diameter of the first blade is equal to the diameter of the inner arc groove. Multiple first blades 202 are respectively fixed on the top of the first flange of the first blade body 201. One side wall of the first blade is flush with the side wall of the first flange. The inner surface of the first blade is in contact with the first flange and the axial dimension of the top of the first blade is equal to that of the top of the first flange.

[0058] The external arc groove milling cutter 3 includes a second cutter body 301 and a second insert 302; the second cutter body 301 is a stepped shaft shape, with a blind hole in the middle of the large end along the axial direction, and a plurality of second flanges are radially provided on the inner end face of the blind hole. The blind hole can accommodate one side wall of the semi-open cavity structure at the end of the part and can make the second flanges located at the external arc groove machining position on the side wall. The small end of the second cutter body is used to be fixedly connected to the spindle of a three-axis vertical CNC milling machine.

[0059] The second blade 302 is bent, and its shape and bending angle are the same as the outer arc groove to be processed. The inscribed circle diameter of the second blade is the same as the diameter of the outer arc groove. Multiple second blades 302 are respectively fixed on the top of the second flange of the second blade body 301. One side wall of the second blade is flush with the side wall of the second flange. The inner surface of the second blade is in contact with the second flange and the axial dimension of the top of the second blade is equal to that of the top of the second flange.

[0060] Reference Figures 7-10 The internal arc groove end mill 2 is an integral stepped shaft-like part with a flange, comprising a first cutter body 201 and a first insert 202, which are welded together. The first cutter body 201 is made of alloy structural steel, and the first insert 202 is made of cemented carbide.

[0061] The first cutter body 201 is a stepped shaft shape, with the large end being the first cutter head 20102, which is conical. The conical shape ensures the strength of the cutter body while avoiding interference between the first cutter body and the part. Six radially extending first flanges 20103 are evenly distributed on the edge of the large end face. The first flanges 20103 are toothed. A blind hole is opened axially in the middle of the large end of the first cutter body. This blind hole can accommodate one side of the semi-open cavity structure at the end of the part and allows the first flange to be located in the inner arc groove machining position on the other side wall, avoiding interference between the first cutter body and the part. When machining the inner arc groove, the unmachined side of the semi-open cavity structure is located in the blind hole.

[0062] Specifically, to avoid the arc protrusion on the end face where the outer arc groove is located, the minimum limit diameter of the blind hole is taken as the diameter d1 of the circumscribed circle formed by the arc boss on the end face where the outer arc groove is located. Since the center of the circumscribed circle formed by the arc boss on the end face where the outer arc groove is located is different from the tool rotation center, the minimum diameter of the blind hole is taken as the diameter d2 of the inscribed circle formed by the circumscribed circle formed by the arc boss on the end face where the outer arc groove is located at the tool rotation center. The diameter of the blind hole is equal to the sum of the minimum diameter and the machining interpolation amount, which is 5mm to 10mm. The depth of the blind hole is the maximum distance b from the sidewall of the annular groove to the end face boss plus 5mm to 10mm of clearance space and chip space to avoid interference between the tool and the workpiece. A center hole is provided at the bottom center of the blind hole, which is a process hole for convenient tool clamping during tool processing.

[0063] The small end of the first tool body is cylindrical, serving as the first tool holder 20101, used for fixed connection to the spindle of a three-axis vertical CNC milling machine. The tool holder end is used in conjunction with an ER spring collet to fix the tool on the spindle of the three-axis vertical machining center.

[0064] The first blade 202 is bent, with the same shape and bending angle as the inner arc groove to be machined, and the circumscribed circle diameter of the first blade is equal to the diameter of the inner arc groove. Six first blades 202 are welded and fixed to the top of the first flange of the first tool body. The outer surface 20202 of the first blade is flush with one side wall of the first flange, while the inner surface 20201 of the first blade is not flush with the other side wall of the first flange. The two inner surfaces of the first blade are respectively in contact with the surface of the first flange, and in the tool axis, the cutting edge of the first blade protrudes 2mm from the lower surface of the first tool body flange. This avoids interference between the lower surface of the first tool body flange and the workpiece's machined surface, and ensures that the inner and outer end teeth and circumferential teeth of the blade can participate in the cutting process simultaneously. The circumscribed circle diameter formed by the first blade is the same as the diameter of the inner arc groove of the workpiece.

[0065] Reference Figures 11-13 The external arc groove end mill 3 is an integral stepped shaft-type part, including a second cutter body 301 and a second insert 302, which are welded together. The second cutter body 301 is an alloy structural steel cutter body, and the second insert 302 is a carbide insert.

[0066] The second cutter body 301 is a stepped shaft shape, with the large end being the second cutter head 30102. A blind hole is provided axially in the middle of the cutter head, and four second flanges 30103 are radially arranged on the inner end face of the blind hole. Each second flange 30103 has a toothed protrusion. This blind hole can accommodate one sidewall of the semi-open cavity structure at the end of the part and allows the second flanges to be positioned at the machining position of the outer arc groove on that sidewall, preventing interference between the second cutter body 301 and the part. When machining the outer arc groove, the machining side of the semi-open cavity structure is located within the blind hole.

[0067] Specifically, to avoid the convexity of the end face where the outer arc groove is located, the minimum limit diameter of the blind hole is taken as the diameter d1 of the circumscribed circle formed by the arc boss on the end face where the outer arc groove is located. Since the center of the circumscribed circle formed by the arc boss on the end face where the outer arc groove is located is different from the tool rotation center, the minimum diameter of the blind hole is taken as the diameter d2 of the inscribed circle formed by the circumscribed circle formed by the arc boss on the end face where the outer arc groove is located at the tool rotation center. The diameter of the blind hole is equal to the sum of the minimum diameter and the machining interpolation amount, which is 5mm to 10mm. The depth of the blind hole is the maximum distance b from the sidewall of the annular groove to the end face boss plus 5mm to 10mm for clearance space and chip space to avoid interference between the tool and the workpiece. The small end of the second tool body 301 is used to be fixedly connected to the spindle of the three-axis vertical CNC milling machine. At the center of the bottom surface of the blind hole, there is a center hole, which is a process hole for convenient tool clamping during tool processing. The tool holder at the small end of the second tool body is cylindrical and is used in conjunction with an ER spring collet to fix the tool on the spindle of a three-axis vertical machining center.

[0068] The second insert 302 is bent, with the same shape and bending angle as the outer arc groove to be machined, and the inscribed circle diameter of the second insert is the same as the diameter of the outer arc groove. Four second inserts 302 are respectively fixed to the top of the second flange of the second cutter body 301. The outer surface 30202 of the second insert is flush with one side wall of the second flange, while the inner surface 20201 of the first insert is not flush with the other side wall of the first flange. The inner surface of the second insert is in contact with the surface of the second flange and is axially aligned with the tool. The cutting edge of the second insert protrudes 2mm from the lower surface of the second cutter body flange, ensuring that the bottom teeth of the second insert participate in the cutting process while avoiding interference between the lower surface of the second cutter body flange and the machined surface of the part. The inscribed circle diameter formed by the first insert is the same as the diameter of the outer arc groove of the machined part.

[0069] The specific machining methods for machining internal hole grooves and external cylindrical grooves using milling tools provided by this invention are as follows:

[0070] 1. The workpiece 1 is vertically fixed on the worktable of the three-axis vertical machining center using a self-centering three-jaw chuck;

[0071] 2. The internal arc groove end mill 2 and the external arc groove end mill 3 are respectively fixed on the spindle of the vertical machining center using ER spring collets;

[0072] 3. During machining, the unmachined part of the part is located in the blind hole at the large end of the inner arc groove milling cutter 2, the first insert is located at the position of the inner arc groove to be machined, and the inner arc groove is machined by CNC milling in one operation using the inner arc groove milling cutter 2.

[0073] 4. During machining, position the machining portion of the part in the blind hole at one of the three ends of the external arc groove milling cutter, with the second insert positioned at the location of the external arc groove to be machined. Use the external arc groove milling cutter to complete the machining of the external arc groove in one CNC milling operation.

[0074] This invention is versatile and widely applicable, and is not limited by the parts being processed or the production conditions. By changing the tool structure dimensions and the shape of the insert, and adjusting the CNC program, it is possible to achieve milling of outer arc grooves and inner arc annular grooves with different cross-sectional shapes and different eccentric distances.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A milling cutter for machining an annular groove offset from the rotation center of a part, the annular groove comprising an inner circular arc groove (101) and an outer circular arc groove (102), respectively located inside the end face circular arc bosses on both sides of the semi-open cavity structure of the rotating part, wherein the axial and radial dimensions of the end face circular arc boss where the inner circular arc groove is located are the same as the axial and radial dimensions of the end face circular arc boss where the outer circular arc groove is located, and the arc length of the end face circular arc boss where the outer circular arc groove is located is less than the length of the end face circular arc boss where the inner circular arc groove is located; characterized in that, The milling cutter includes an inner circular arc groove cutter (2) and an outer circular arc groove cutter (3); The inner arc groove milling cutter (2) includes a first cutter body (201) and a first insert (202). The first cutter body (201) is a stepped shaft with a conical end. Multiple radially extending first flanges (20103) are evenly distributed on the edge of the end face. The first flanges are toothed. A blind hole is opened in the middle of the large end of the first cutter body along the axial direction. The blind hole can accommodate one side of the semi-open cavity structure at the end of the part and can make the first flange located at the inner arc groove machining position on the other side wall. The small end of the first cutter body is used to be fixedly connected to the spindle of a three-axis vertical CNC milling machine. The first blade (202) is bent, and its shape and bending angle are the same as the inner arc groove to be processed. The outer diameter of the first blade is equal to the diameter of the inner arc groove. Multiple first blades (202) are respectively fixed on the top of the first flange of the first blade body (201). One side wall of the first blade is flush with one side wall of the first flange. The inner surface of the first blade is in contact with the first flange. The cutting edge of the first blade protrudes from the first flange in the axial direction. The external arc groove milling cutter (3) includes a second cutter body (301) and a second insert (302); the second cutter body (301) is a stepped shaft, with a blind hole in the middle of the large end along the axial direction, and a plurality of second flanges (30103) are radially provided on the inner end face of the blind hole. The blind hole can accommodate one side wall of the semi-open cavity structure at the end of the part and can make the second flange located at the external arc groove machining position on the side wall. The small end of the second cutter body is used to be fixedly connected to the spindle of a three-axis vertical CNC milling machine. The second blade (302) is bent, and its shape and bending angle are the same as the outer arc groove to be processed. The inscribed circle diameter of the second blade is the same as the diameter of the outer arc groove. Multiple second blades (302) are fixed on the top of the second flange of the second blade body (301). One side wall of the second blade is flush with the side wall of the second flange. The inner surface of the second blade is in contact with the second flange. The cutting edge of the second blade protrudes from the second flange in the axial direction.

2. The milling tool for machining annular grooves according to claim 1, characterized in that, The thickness of the first blade (202) and the second blade (302) is 4-6 mm.

3. The milling tool for machining annular grooves according to claim 2, characterized in that, The first blade (202) is welded and fixed to the first flange end face of the first blade body; the second blade (302) is welded and fixed to the second flange end face of the second blade body.

4. The milling cutter for machining annular grooves according to claim 3, characterized in that, The small ends of the first cutter body (201) and the second cutter body (301) are respectively fixed to the spindle of the three-axis vertical CNC milling machine through ER spring collets.

5. The milling cutter for machining annular grooves according to claim 1, characterized in that, Along the tool axis, the cutting edge portions of the first and second inserts protrude 2mm beyond the first and second flanges, respectively.

6. The milling tool for machining annular grooves according to claim 1, characterized in that, The diameter and depth of the blind holes at the large ends of the first cutter body (201) and the second cutter body (301) are determined according to the following dimensions: The minimum limit diameter of a blind hole is equal to the diameter (d1) of the circumcircle formed by the circular arc boss on the end face where the outer circular arc groove is located. The minimum diameter of the blind hole is equal to the diameter (d2) of the inscribed circle formed by the circumscribed circle of the outer arc groove at the end face of the circular arc boss at the tool rotation center. The diameter of the blind hole is equal to the sum of the minimum diameter and the machining interpolation amount, wherein the machining interpolation amount is 5mm to 10mm; The depth of the blind hole is equal to the sum of the maximum distance (b) from the sidewall of the annular groove to the end face arc boss and the clearance dimension, which is 5mm to 10mm.

7. The milling cutter for machining annular grooves according to any one of claims 1-6, characterized in that, The first cutter body (201) and the second cutter body (301) are both alloy structural steel cutter bodies, and the first blade (202) and the second blade (302) are both cemented carbide blades.

8. The milling cutter for machining annular grooves according to claim 7, characterized in that, Process holes are provided along the axis at the bottom of the blind holes at the large end of the first cutter body (201) and the large end of the second cutter body (301).

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