Titanium alloy cabin inner cavity double-cutting point processing method

Abstract

The application relates to a double-cutting-point machining method for a titanium alloy casting cabin inner cavity, and belongs to the field of turning machining, which solves the problem that in the prior art, the part frequently impacts the tool, leading to rapid tool breakage or wear. The double-cutting-point machining method comprises the steps of synchronously cutting the titanium alloy casting cabin inner cavity by using a first ball head cutting edge and a second ball head cutting edge; wherein, during the cutting, the lower edges of the first ball head cutting edge and the second ball head cutting edge are not flush, and along the cutting advancing direction, the first ball head cutting edge and the second ball head cutting edge are flush arranged. The service life of the tool is improved during the intermittent machining process, and the machining efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of turning technology, and in particular to a method for machining the inner cavity of a titanium alloy casting chamber using two cutting points. Background Technology

[0002] Titanium alloys are high-performance metallic materials with advantages such as low density and high specific strength, and are widely used in various fields such as aviation, aerospace, and shipbuilding. Large titanium alloy castings have large external dimensions and complex structures, and the parts are characterized by weak rigidity and poor tool accessibility.

[0003] Currently, turning is the common machining method for the inner cavity of large titanium alloy castings. Existing turning tools typically use a single cutting edge, repeatedly turning to complete the machining. However, due to the multiple axial ribs within the part's inner cavity, and the uneven distribution of these ribs with varying machining allowances (typically 3-5mm), "intermittent machining" occurs during the turning of large titanium alloy castings. "Intermittent machining" has always been a major challenge in turning, primarily due to the frequent impact of the part on the tool, leading to rapid tool chipping or wear—a persistent and difficult problem in the industry. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a dual-cutting-point machining method for the inner cavity of a titanium alloy casting, in order to solve the problem that existing machining methods are prone to tool chipping or wear, which affects machining efficiency.

[0005] This invention provides a dual-cutting-point machining method for the inner cavity of a titanium alloy casting chamber, comprising simultaneously cutting the inner cavity of the titanium alloy casting chamber using a first ball-end cutting edge and a second ball-end cutting edge;

[0006] During cutting, the lower edges of the first ball-end cutting edge and the second ball-end cutting edge are not aligned, but along the cutting direction, the first ball-end cutting edge and the second ball-end cutting edge are aligned.

[0007] Based on a further improvement of the above method, during cutting, the depth of cut 'a' of the first ball-end cutting edge satisfies:

[0008]

[0009] Among them, H Ⅰ H represents the material hardness of the first ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K a The correction factor ranges from 3.0 to 8.9; D is the diameter of the first ball end cutting edge, ranging from 6 to 12 mm.

[0010] The depth of cut b of the second ball-end cutting edge satisfies:

[0011]

[0012] Among them, H Ⅱ H represents the material hardness of the second ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K b The value is a correction factor, ranging from 2.6 to 8.9; D is the diameter of the second ball end cutting edge, ranging from 6 to 12 mm.

[0013] In this case, the depth of cut of a machining trajectory is the sum of the depths of cut of the first ball end cutting edge and the second ball end cutting edge.

[0014] Based on a further improvement of the above method, during cutting, the working rake angle α of the first ball end cutting edge satisfies:

[0015]

[0016] Among them, H Ⅰ H represents the material hardness of the first ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K α is a correction factor, with a value range of 16.9 to 25.9; a is the depth of cut of the first ball end cutting edge.

[0017] Based on a further improvement of the above method, during cutting, the working rake angle β of the second ball end cutting edge satisfies:

[0018]

[0019] Among them, H Ⅱ H represents the material hardness of the second ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K β is a correction factor, with a value range of 14.2 to 25.3; b is the depth of cut of the second ball end cutting edge.

[0020] Based on a further improvement of the above method, the first ball-end cutting edge and the second ball-end cutting edge perform circumferential cutting by axially advancing or exiting along the inner cavity of the titanium alloy casting chamber.

[0021] During cutting, the cutting direction at any given moment is perpendicular to the axial infeed or axial exit direction of the first and second ball-end cutting edges.

[0022] Based on a further improvement of the above method, during axial feed, the distance between the lower edge of the first ball-end cutting edge and the second ball-end cutting edge is the same as the depth of cut of the second ball-end cutting edge;

[0023] When the cutting tool is extended axially, the distance between the lower edges of the first ball-end cutting edge and the second ball-end cutting edge is the same as the depth of cut of the first ball-end cutting edge.

[0024] Based on the further improvement of the above method, during axial feed, when the first ball-end cutting edge is machined to the inner cavity near the bottom of the titanium alloy casting chamber, the distance between the first ball-end cutting edge, the second ball-end cutting edge and the inner cavity of the titanium alloy casting chamber is adjusted by the adjustment mechanism to machine the inner cavity at the bottom of the titanium alloy casting chamber.

[0025] Based on further improvements to the above method, during cutting, gas and cutting fluid are sprayed from the first and second channels respectively along the cutting direction to cool, lubricate, and remove debris from the gap between the adjacent surfaces of the first and second ball-end cutting edges.

[0026] Based on a further improvement of the above method, during cutting, the titanium alloy casting chamber rotates counterclockwise at a speed of 29-37 r / min.

[0027] Based on further improvements to the above method, the axial feed or axial exit speed of the first and second ball-end cutting edges is 0.1-0.2 mm / r.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] 1. The dual-cutting-point machining method of the present invention uses two ball-end cutting edges that are parallel and have uneven lower edges to perform cutting along the cutting direction. The depth of cut of one machining trajectory is the sum of the depths of cut of the two ball-end cutting edges, which improves machining efficiency. During cutting, two ball-end cutting edges with different working rake angles are used to reduce the impact of uneven machining allowance ribs in the inner cavity of the titanium alloy casting on the tool life. That is, a ball-end cutting edge with a smaller working rake angle is used to bear the main impact, and a ball-end cutting edge with a larger working rake angle is used to ensure the overall sharpness of the tool. In this way, the tool life is improved and the machining efficiency is improved.

[0030] 2. The cutting tool used in this invention is a double-point staggered tool composed of two ball-end cutting edges, that is, the two ball-end cutting edges cut synchronously, and the distance difference between the lower edges of the two ball-end cutting edges is not equal to 0. In this way, the depth of cut of the machine tool in one machining trajectory is the sum of the depths of cut of the two ball-end cutting edges, which improves the efficiency of single cutting. In addition, by setting the working rake angle combination of the two ball-end cutting edges, that is, α < β, the overall sharpness of the machining tool is improved while ensuring the overall impact resistance of the machining tool, thereby improving the machining efficiency.

[0031] 3. This invention adjusts the relative positions of the first and second carriers by using a depth-of-cut adjustment gear, thereby precisely adjusting the depth of cut of the ball end cutting edge and adjusting the position of each cutting edge relative to the inner cavity of the titanium alloy casting chamber during the machining process. In this way, reciprocating cutting can be achieved on the one hand, and cutting can be performed on the inner cavity near the bottom of the titanium alloy casting chamber on the other hand, so as to achieve all-round machining of the inner cavity of the titanium alloy casting chamber without dead angles, thereby improving machining efficiency.

[0032] 4. The dual-cutting-point machining method of the present invention can improve the tool life and avoid frequent tool replacement, thereby improving machining efficiency. The machining time of a single titanium alloy casting chamber cavity can be as low as 4.5 hours, which is about twice as efficient as the prior art.

[0033] 5. When machining the inner cavity of a titanium alloy casting chamber, this invention uses two ball-end cutting edges to share the machining amount, reducing the machining amount borne by a single cutting edge. Compared with the prior art, when machining a single part, the wear borne by a single cutting edge is reduced, thus improving the tool life. Furthermore, one ball-end cutting edge bears the main impact with a smaller working rake angle, protecting the other ball-end cutting edge. That is, in the initial state, the machining allowance of the ribs in the inner cavity of the titanium alloy casting chamber is uneven. One ball-end cutting edge contacts the ribs first. The ball-end cutting edge with a smaller working rake angle has better impact resistance and bears the main impact. The end face of this ball-end cutting edge after machining is a uniform end face, avoiding the phenomenon of local discontinuous cutting caused by the uneven end face, thereby reducing the impact on the other ball-end cutting edge and thus improving the service life of the machining tool.

[0034] 6. By using the cutting fluid ejection channel and the gas ejection channel set on the first carrier, the gap between the cutting edges can be cooled and lubricated, solving the problem that existing cutting fluid supply methods may not be able to reach the gap. This achieves all-round cooling and lubrication of the cutting edges. At the same time, it can remove the debris adhering to the gap between the cutting edges and prevent debris from rubbing against the cutting edges, thereby further improving the service life of the tool. The service life of a single cutting edge is at least 8.2 hours, which is 16.4-24.6 times higher than the existing technology.

[0035] 7. Both ball-head cutting edges of the present invention can be circular blades, and the working rake angle of each angle of the circular blade is the same. Therefore, when the cutting end of the blade breaks, it is only necessary to rotate the circular blade, and the unbroken part can continue to cut with the original cutting depth and working rake angle. The utilization rate of a single blade is improved, the cost is reduced, and there is no need to adjust the cutting depth and working rake angle during the installation process, which improves the installation efficiency and thus improves the overall processing efficiency.

[0036] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from the description and drawings, which are particularly pointed out. Attached Figure Description

[0037] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0038] Figure 1 This is a flowchart of the double-cutting-point machining method for the inner cavity of the titanium alloy casting chamber according to the present invention;

[0039] Figure 2 This is a schematic diagram of the cooperation structure between the dual-cutting-point tool and the titanium alloy casting chamber in the axial feed direction of the present invention;

[0040] Figure 3 This is a schematic diagram of the cooperation structure between the dual-cutting-point tool and the titanium alloy casting chamber in the cutting forward direction of the present invention;

[0041] Figure 4 This is a schematic diagram of the mating structure between the first ball-end cutting edge and the first carrier body in the axial feed direction of the present invention;

[0042] Figure 5 This is a three-dimensional schematic diagram of the cooperation structure between the first ball-end cutting edge, the second ball-end cutting edge, and the tool holder in the cutting forward direction of the present invention;

[0043] Figure 6 This is a schematic diagram of the cooperation structure between the first ball-end cutting edge and the second ball-end cutting edge in the cutting forward direction in this invention;

[0044] Figure 7 This is a cross-sectional view of the first support body, the second support body, and the tool holder in this invention.

[0045] Figure 8 for Figure 7 Schematic diagram of the cross section at point AA;

[0046] Figure 9 for Figure 8 A schematic diagram of the mating structure of the first and second load-bearing bodies at the mid-section;

[0047] Figure 10 This is a schematic diagram of the tool holder structure in this invention;

[0048] Figure 11 This is a schematic diagram of the processing device in this invention.

[0049] Figure label:

[0050] 1-Tool holder; 101-Rectangular through slot; 102-Protrusion; 2-First support body; 3-Second support body; 4-First ball end cutting edge; 5-Second ball end cutting edge; 6-Depth of cut adjustment gear; 7-Rectangular groove; 8-Groove; 9-First channel; 10-Second channel; 11-Titanium alloy casting chamber; 12-Direction of rotation of titanium alloy casting chamber around axis; 13-Axis of titanium alloy casting chamber; 14-Axial feed direction of double-point tool; 15-Cutting forward direction; 16-Force direction of first ball end cutting edge; 17-Tool holder; 18-Base; 19-Upper ring; 20-Lower ring; 21-Screw; 22-Machining reference surface of first ball end cutting edge; 23-The The machining reference surface for two ball-end cutting edges; α1 - fixed value of the rake angle of the first ball-end cutting edge; α2 - installation rake angle of the first ball-end cutting edge; C - distance between the lower edges of the first and second ball-end cutting edges; D - diameter of the second ball-end cutting edge; R - distance between adjacent side edges of the first and second ball-end cutting edges; a - depth of cut of the first ball-end cutting edge with its machining reference surface as the reference; b - depth of cut of the second ball-end cutting edge with its machining reference surface as the reference; w1 - diameter of the depth of cut adjustment gear; w2 - length of the upper end of the first carrier; w3 - groove depth of the rectangular groove; w4 - side wall length of the rectangular groove; w5 - width of the rectangular groove. Detailed Implementation

[0051] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0052] The inner cavity of a large metal casting chamber is a shell component on an aircraft. Its blank is a titanium alloy barrel-shaped casting chamber with a maximum diameter of 760mm, a maximum machining depth of 920mm, and a wall thickness of 4-5mm. There are multiple axial ribs irregularly distributed inside the casting chamber cavity. The machining allowance of the ribs is uneven, generally 3-5mm. During the machining of the casting chamber cavity, there is a situation of "intermittent machining", which causes the casting chamber to frequently impact the tool, causing the tool to break or wear quickly.

[0053] To solve the above problems, the present invention provides a dual-cutting-point machining method for the inner cavity of a titanium alloy casting chamber, which includes simultaneously cutting the inner cavity of the titanium alloy casting chamber 11 using a first ball-end cutting edge 4 and a second ball-end cutting edge 5.

[0054] During cutting, the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are not flush, but they are flush along the cutting direction. In other words, during the circumferential cutting along the inner cavity of the titanium alloy casting chamber 11, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 move in parallel, and their cutting depths along the inner cavity of the titanium alloy casting chamber 11 differ.

[0055] Compared with existing technologies, this invention uses a tool composed of two ball-end cutting edges with parallel cutting edges for machining along the cutting direction. During machining, the ball-end faces of the ball-end cutting edges are located in the same plane, and there is a height difference between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, i.e., the distance difference between the lower edges of the two ball-end cutting edges is not equal to 0. The two cutting edges cut simultaneously, forming a tool with double-point misalignment for double-point misalignment machining. In this way, the depth of cut of the machine tool in one machining trajectory is the sum of the depths of cut of the two ball-end cutting edges, which improves the efficiency of a single cutting operation. At the same time, the tool has a long service life, thus avoiding frequent tool replacements and improving machining efficiency. The machining time for a single titanium alloy casting chamber cavity can be as low as 4.5 hours, which is about twice the machining efficiency compared to existing technologies.

[0056] During cutting, the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are not flush, meaning there is a height difference between their lower edges. Both cutting edges move synchronously, creating a double-point misaligned tool for double-point misaligned machining. For example, the depth of cut of the first ball-end cutting edge 4 is 'a', the depth of cut of the second ball-end cutting edge 5 is 'b', and the distance between the lower edges of the second ball-end cutting edge 5 and the first ball-end cutting edge 4 is C = b > 0. The depth of cut Y = a + b is the depth of cut for one machining path.

[0057] Specifically, before cutting, the depth of cut of the ball end cutting edge is determined based on the material hardness of the ball end cutting edge and the hardness of the casting material to be processed, in order to improve the service life and processing efficiency of the two ball end cutting edges.

[0058] Specifically, the depth of cut 'a' of the first ball-end cutting edge 4 satisfies:

[0059]

[0060] Among them, H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0061] H 钛合金 The hardness of titanium alloy casting material 11;

[0062] K a This is a correction factor, with a value ranging from 3.0 to 8.9;

[0063] D is the diameter of the first ball-end cutting edge 4, and its value ranges from 6 to 12 mm.

[0064] Specifically, the depth of cut b of the second ball-end cutting edge 5 satisfies:

[0065]

[0066] Among them, H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0067] H 钛合金 The hardness of titanium alloy casting material 11;

[0068] K b This is a correction factor, with a value ranging from 2.6 to 8.9;

[0069] D is the diameter of the second ball-end cutting edge 5, and its value ranges from 6 to 12 mm.

[0070] For example, the diameter D is 12mm, H 钛合金 For RHC30, the first ball-end cutting edge 4 is made of cemented carbide, H Ⅰ For RHC70, K a The value is 7.10, at which point a = 1 mm.

[0071] For example, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have the same shape, size, and material. In this case, H Ⅰ =H Ⅱ =RHC70; where K b The value is 6.47, at which point b = 1.1 mm.

[0072] Furthermore, the working rake angles of the two ball-end cutting edges are set to cooperate with each other. The working rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 overcome the impact of uneven machining allowance ribs within the inner cavity of the titanium alloy casting 11, thereby improving machining efficiency and tool life. For example, the working rake angle α of the first ball-end cutting edge 4 is set to be relatively small to bear the main impact and protect the second ball-end cutting edge 5. The value of α is determined by the hardness of the titanium alloy casting 11 material and the depth of cut of the first ball-end cutting edge 4. The working rake angle β of the second ball-end cutting edge 5 is greater than α, i.e., α < β, to improve its sharpness and thus improve the overall machining efficiency.

[0073] Specifically, the working rake angle α of the first ball end cutting edge 4 satisfies:

[0074]

[0075] Among them, H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0076] H 钛合金 The hardness of titanium alloy casting material 11;

[0077] K α This is a correction factor, with a value ranging from 16.9 to 25.9;

[0078] a represents the depth of cut of the first ball-end cutting edge 4.

[0079] Specifically, the working rake angle β of the second ball end cutting edge 5 satisfies:

[0080]

[0081] Among them, H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0082] H 钛合金 The hardness of titanium alloy casting material 11;

[0083] K β This is a correction factor, with a value range of 14.2 to 25.3;

[0084] b is the depth of cut of the second ball-end cutting edge 5.

[0085] For example, K α H is 20.33. Ⅰ For RHC70, H 钛合金 For RHC30, a is 1 mm, and α = -1.5°.

[0086] For example, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have the same shape, size, and material. In this case, H Ⅰ =H Ⅱ =RHC70; where K β Since the value is 18.08 and b = 1.1 mm, β = 0.5°.

[0087] The first ball-end cutting edge 4 and the second ball-end cutting edge 5 are components of a double-point cutting tool. Specifically, the double-point cutting tool includes a tool holder 1, a first support body 2 and a second support body 3 mounted on the tool holder 1. The first ball-end cutting edge 4 is mounted in a first mounting groove at the lower end of the first support body 2, and the second ball-end cutting edge 5 is mounted in a second mounting groove at the lower end of the second support body 3.

[0088] Generally, the rake angle of the ball end mill is a fixed value. After determining the working rake angles of the first ball end mill 4 and the second ball end mill 5, the working rake angles of the first ball end mill 4 and the second ball end mill 5 are adjusted by setting the inclination of the bottom surfaces of the first and second mounting grooves. The bottom surfaces are the surfaces that contact the mounting surfaces of the first ball end mill 4 or the second ball end mill 5. For example, the fixed rake angles of the first ball end mill 4 and the second ball end mill 5 are α1 and β1, respectively, and the mounting rake angles of the first ball end mill 4 and the second ball end mill 5 are α2 and β2, respectively. The working rake angle of the first ball end mill 4 is α = α1 + α2, and the working rake angle of the second ball end mill 5 is β = β1 + β2.

[0089] For example, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have the same shape. In this case, the fixed rake angles α1 and β1 of the two ball-end cutting edges satisfy: α1 = β1, specifically 1.5°. Therefore, according to the formulas α = α1 + α2 and β = β1 + β2, the installation rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 can be calculated. That is, the installation rake angle α2 of the first ball-end cutting edge 4 is α - α1 = -1.5° - 1.5° = -3°, and the installation rake angle β2 of the second ball-end cutting edge 5 is β - β1 = 0.5° - 1.5° = -1°.

[0090] Furthermore, after determining the depth of cut and working rake angle of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, the distance difference between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is adjusted. For example, during axial feed, the distance difference between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is the same as the depth of cut of the second ball-end cutting edge 5; during axial exit, the distance difference between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is the same as the depth of cut of the first ball-end cutting edge 4.

[0091] Specifically, after determining the difference in the lower edge distance between the first ball-end cutting edge 4 and the second ball-end cutting edge 5, the first support body 2 and the second support body 3 are moved up and down to adjust the relative position of the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0092] The first support body 2 and the second support body 3 are movably arranged within the tool holder 1 to facilitate position adjustment. Specifically, the tool holder 1 has a rectangular through slot 101. The inner wall of the rectangular through slot 101 has multiple protrusions 102 penetrating the upper and lower end faces of the tool holder 1. The outer surfaces of the first support body 2 and the second support body 3 have multiple grooves 8 penetrating the upper and lower end faces of the two support bodies. One side of the first support body 2 and the second support body 3 are inserted into the rectangular through slot 101, and the multiple grooves 8 on the outer surface of the first support body 2 correspond to the multiple protrusions 102 on the inner wall of the rectangular through slot 101. The multiple grooves 8 on the outer surface of the second support body 3 correspond to the multiple protrusions 102 on the inner wall of the rectangular through slot 101. Under the action of external force, the first support body 2 and the second support body 3 can move up and down within the rectangular through slot 101 of the tool holder 1.

[0093] The adjustment mechanism allows external force to be applied to move the first support 2 and the second support 3 up and down within the rectangular through slot 101 of the tool holder 1. Specifically, the adjustment mechanism includes a depth-of-cut adjustment gear 6. To form an internal cavity to accommodate the depth-of-cut adjustment gear 6, rectangular slots 7 are provided on the mating surfaces of the first support 2 and the second support 3. These rectangular slots 7 together form the internal cavity to accommodate the depth-of-cut adjustment gear 6. The bottom surface of the rectangular slot 7 is a toothed surface that meshes with the depth-of-cut adjustment gear 6. The adjustment mechanism also includes a rotating shaft, one end of which is connected to the depth-of-cut adjustment gear 6, and the other end is connected to a drive assembly mounted on the tool holder 1. To facilitate the application of external force, two rotating shafts can be used, respectively positioned at both ends of the depth-of-cut adjustment gear 6.

[0094] When the depth of cut needs to be adjusted, the drive assembly is activated, and the depth of cut adjustment gear 6 rotates under the action of the drive assembly. In the initial state, the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are flush. If the depth of cut adjustment gear 6 rotates clockwise, the first carrier 2 drives the first ball-end cutting edge 4 away from the inner wall of the titanium alloy casting chamber 11, and the second carrier 3 drives the second ball-end cutting edge 5 closer to the inner wall of the titanium alloy casting chamber 11, thereby realizing the adjustment of the distance difference C between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0095] Among them, when the depth of cut adjustment gear 6 rotates clockwise, the distance P1 that the first ball-end cutting edge 4 moves away from the end face of the inner cavity of the titanium alloy casting chamber 11 satisfies:

[0096] P1 = v1 * t1

[0097] Wherein, v1 is the linear velocity of the side end face when the depth of cut adjustment gear 6 rotates;

[0098] t1 is the rotation time of the depth-of-cut adjustment gear 6.

[0099] The distance P2 that the second ball-end cutting edge 5 moves close to the inner end face of the titanium alloy casting chamber 11 satisfies:

[0100] P2 = P1

[0101] therefore,

[0102] At this point, the rotation time of the depth-of-cut adjusting gear 6 is:

[0103]

[0104] In this way, the positions of the first support 2 and the second support 3 can be precisely adjusted.

[0105] Furthermore, after determining the distance difference between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, the inner cavity of the titanium alloy casting chamber is machined using the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0106] Specifically, during machining, the titanium alloy casting chamber 11 rotates at a speed of v2 = 29~37 r / min, and the first ball-end cutting edge 4 and the second ball-end cutting edge 5 feed at a speed of 0.1-0.2 mm / r.

[0107] Specifically, during the initial machining of the inner cavity of the titanium alloy casting chamber 11, the first ball-end cutting edge 4 first cuts the inner cavity of the titanium alloy casting chamber 11. At this time, the second ball-end cutting edge 5 is in an idle state for a period of time. Then, the tool is fed axially. During this process, the second ball-end cutting edge 5 cuts the surface processed by the first ball-end cutting edge 4. At this time, the depth of cut of a machining trajectory is Y = a + b, which greatly improves the machining efficiency.

[0108] In the initial state, the irregular ribs in the inner cavity of the titanium alloy casting chamber 11 have irregular machining allowances. The first ball-end cutting edge 4 bears the impact of the irregular allowance ribs with a small working rake angle to protect the second ball-end cutting edge 5. The second ball-end cutting edge 5 has a larger working rake angle to improve the sharpness during cutting, thereby improving the overall machining efficiency and service life of the double-cutting point tool.

[0109] When the first ball-end cutting edge 4 moves axially to the inner cavity at the bottom of the titanium alloy casting chamber 11, the distance between the first ball-end cutting edge 4, the second ball-end cutting edge 5 and the inner cavity of the titanium alloy casting chamber 11 is adjusted by the adjustment mechanism to process the inner cavity at the bottom of the titanium alloy casting chamber 11.

[0110] Specifically, the depth-of-cut adjusting gear 6 is rotated counterclockwise for a period of time. At this point, the first ball-end cutting edge 4 continues cutting, with a depth of cut of v1*t3; after a period of time Then, continue to rotate the depth-of-cut adjusting gear 6 counterclockwise. The rotation time of the depth-of-cut adjusting gear 6 is... At this time, the first ball-end cutting edge 4 continues to cut, with a cutting depth of v1*t5; thus, the first ball-end cutting edge 4 is used to cut the inner cavity at the bottom of the titanium alloy casting 11. Finally, the surface finally machined by the first ball-end cutting edge 4 is flush with the surface finally machined by the second ball-end cutting edge 5.

[0111] Furthermore, after the final machined surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are flush, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are engaged at a speed of 0.1-0.2 mm / r to machine the inner cavity of the titanium alloy casting chamber 11. At this time, the depth of cut of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 remains unchanged, and the distance between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is adjusted to 'a', so that the first ball-end cutting edge 4 is closer to the inner wall of the titanium alloy casting chamber 11 than the second ball-end cutting edge 5.

[0112] During the process of adjusting the depth of cut of the first ball end cutting edge 4 to a, the first ball end cutting edge 4 first cuts the inner cavity at the bottom of the titanium alloy casting chamber 11. At this time, the second ball end cutting edge 5 is in an idle state. When the depth of cut of the second ball end cutting edge 5 reaches b, the depth of cut of the first ball end cutting edge 4 in the inner cavity at the bottom of the titanium alloy casting chamber is a+b. When the depth of cut of the second ball end cutting edge 5 reaches b, the first ball end cutting edge 4 and the second ball end cutting edge 5 start to exit at a speed of 0.1-0.2 mm / r. At this time, the depth of cut Y of one machining trajectory is Y = a+b, which greatly improves the machining efficiency.

[0113] Furthermore, during cutting, along the direction of cutting, a cleaning device is used to cool, lubricate, and remove debris from the gap between the adjacent surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0114] The aforementioned cleaning device includes a first channel 9 and a second channel 10 for gas and liquid flow on the first carrier 2. Along the cutting direction, the air jet of the first channel 9 and the liquid jet of the second channel 10 are located at the rear ends of the ball faces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, respectively, and are positioned towards the gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5. In this way, the ejected gas increases the flow rate of the cutting fluid, thereby improving the efficiency of chip removal. Simultaneously, it increases the airflow velocity over the surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, thereby improving the cooling effect on the dual-point cutting tool.

[0115] Specifically, along the cutting direction, the air jet of the first channel 9 is located at the lower end of the liquid spray port of the second channel 10. For example, the first channel 9 is used for air or nitrogen flow, and the air outlet velocity of the first channel 9 is 8–10 m / s; the second channel 10 is used for cutting fluid flow, and the liquid outlet velocity of the second channel 10 is 0.25–0.3 m / s. An air supply device and a liquid supply device are installed outside the first support body 2. The air inlet of the first channel 9 is connected to the air supply device located outside the first support body 2, and the liquid inlet of the second channel 10 is connected to the liquid supply device, so as to achieve stable gas ejection from the first channel 9 and stable cutting fluid ejection from the second channel 10.

[0116] To achieve the aforementioned method for machining the inner cavity of a titanium alloy casting chamber using two cutting points, this invention also provides a cutting tool for machining titanium alloy casting chambers using two cutting points, as shown in the attached figure. Figure 5 As shown, the dual-point cutting tool includes a tool holder 1, a first support body 2 and a second support body 3 mounted on the tool holder 1, a first ball-end cutting edge 4 mounted on the lower end of the first support body 2 and a second ball-end cutting edge 5 mounted on the lower end of the second support body 3;

[0117] like Figure 2-3 As shown, along the cutting direction, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are arranged parallel to each other and cut synchronously; however, the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are not parallel. That is to say, during the circumferential cutting along the inner cavity of the titanium alloy casting chamber 11, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 move in parallel, but the cutting depths of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 along the inner cavity of the titanium alloy casting chamber 11 are different.

[0118] Compared with the prior art, along the cutting direction, the machining tool of the present invention is a ball-end cutting edge with two cutting edges arranged flat. The ball-end surfaces of the ball-end cutting edges are located in the same plane, and there is a height difference between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5. That is, the distance difference between the lower edges of the two ball-end cutting edges is not equal to 0. The two cutting edges are cut synchronously to form a tool with double tangent points misaligned for double tangent point misalignment machining. During the cutting process, the tool cuts circumferentially along the inner cavity of the titanium alloy casting chamber 11 and feeds axially along the inner cavity of the titanium alloy casting chamber 11. After cutting one revolution circumferentially along the inner cavity of the titanium alloy casting chamber 11, a circumferential machining trajectory is formed. The second ball-end cutting edge 5 cuts on the previous machining trajectory formed by the first ball-end cutting edge 4. Thus, the depth of cut of one machining trajectory is the sum of the depths of cut of the two ball-end cutting edges, improving the efficiency of a single cutting operation. Simultaneously, by distributing the cutting amount among the two ball-end cutting edges, the machining amount borne by a single cutting edge is reduced. When machining a single part, the wear on a single cutting edge is reduced, thus increasing the tool life. The long tool life avoids frequent tool replacements, thereby improving machining efficiency. The machining time for a single titanium alloy casting chamber inner cavity can be as low as 4.5 hours, which is approximately double the machining efficiency compared to existing technologies.

[0119] In this machining process, the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are not flush, meaning there is a height difference between their lower edges. Both cutting edges operate synchronously, creating a double-point misaligned tool for machining. For example, the depth of cut of the first ball-end cutting edge 4 is 'a', the depth of cut of the second ball-end cutting edge 5 is 'b', and the distance between the lower edges of the second ball-end cutting edge 5 and the first ball-end cutting edge 4 is C = b > 0. The depth of cut Y = a + b is the depth of cut for one machining trajectory.

[0120] Specifically, such as Figure 5 As shown, the above-mentioned double-cutting-point tool includes a tool holder 1 and a first carrier 2 and a second carrier 3 mounted on the tool holder 1. In order to facilitate the installation and replacement of the ball end cutting edge, the lower end of the first carrier 2 is provided with a first mounting groove for installing the first ball end cutting edge 4, and the lower end of the second carrier 3 is provided with a second mounting groove for installing the second ball end cutting edge 5.

[0121] Specifically, one side of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are respectively screwed into the first mounting groove and the second mounting groove. Along the cutting direction, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have two opposing surfaces. One surface is the mounting surface for mounting the first carrier 2 and the second carrier 3, and the other end face is a convex ball-end surface serving as the working side. The edge of the convex surface is a circular cutting edge, and the diameter of both circular cutting edges is D. The gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is R = 1 / 4D. This smaller gap helps to prevent larger chips from entering the adjacent area of ​​the two ball-end cutting edges, thereby reducing wear on the first ball-end cutting edge 4 and the second ball-end cutting edge 5. At the same time, it facilitates machining of the area near the bottom of the inner cavity of the titanium alloy casting chamber 11, thereby improving machining efficiency. For example, D is 12mm.

[0122] The depth of cut of the ball end cutting edge is determined based on the material hardness of the ball end cutting edge and the hardness of the material to be machined, in order to improve the service life and machining efficiency of the two ball end cutting edges.

[0123] Specifically, the depth of cut 'a' of the first ball-end cutting edge 4 satisfies:

[0124]

[0125] Among them, H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0126] H 钛合金 The hardness of titanium alloy casting material 11;

[0127] K a This is a correction factor, with a value ranging from 3.0 to 8.9;

[0128] D is the diameter of the first ball-end cutting edge 4, and its value ranges from 6 to 12 mm.

[0129] Specifically, the depth of cut b of the second ball-end cutting edge 5 satisfies:

[0130]

[0131] Among them, H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0132] H 钛合金 The hardness of titanium alloy casting material 11;

[0133] K b This is a correction factor, with a value ranging from 2.6 to 8.9;

[0134] D is the diameter of the second ball-end cutting edge 5, and its value ranges from 6 to 12 mm.

[0135] For example, the diameter D is 12mm, H 钛合金 For RHC30, the first ball-end cutting edge 4 is made of cemented carbide, H Ⅰ For RHC70, K a The value is 7.10, at which point a = 1 mm.

[0136] For example, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have the same shape, size, and material. In this case, H Ⅰ =H Ⅱ =RHC70; where K b The value is 6.47, at which point b = 1.1 mm.

[0137] Considering that when machining the inner cavity near the bottom of the titanium alloy casting chamber 11, the aforementioned double-cutting-point tool cannot achieve the final machining of the inner cavity near the bottom of the titanium alloy casting chamber 11, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 of the present invention can move up and down under the drive of the first carrier 2 and the second carrier 3.

[0138] Specifically, the tool holder 1 has a rectangular through slot 101. The inner wall of the rectangular through slot 101 has multiple protrusions 102 that penetrate the upper and lower end faces of the tool holder 1. The outer surfaces of the first support body 2 and the second support body 3 have multiple grooves 8 that penetrate the upper and lower end faces of the two support bodies. One side of the first support body 2 and the second support body 3 are inserted into the rectangular through slot 101 in a close fit. The multiple grooves 8 on the outer surface of the first support body 2 are fitted into the multiple protrusions 102 on the inner wall of the rectangular through slot 101 in a one-to-one correspondence. The multiple grooves 8 on the outer surface of the second support body 3 are fitted into the multiple protrusions 102 on the inner wall of the rectangular through slot 101 in a one-to-one correspondence. Under the action of external force, the first support body 2 and the second support body 3 can move up and down in the rectangular through slot 101 of the tool holder 1.

[0139] Furthermore, an adjustment mechanism can be provided in the tool holder 1 to facilitate the application of external force to enable the first support body 2 and the second support body 3 to move up and down within the rectangular through groove 101 of the tool holder 1.

[0140] Specifically, the adjustment mechanism includes a depth-of-cut adjustment gear 6. In order to form an internal cavity to accommodate the depth-of-cut adjustment gear 6, rectangular grooves 7 are respectively provided on the surfaces of the first support body 2 and the second support body 3 that are in contact with each other. The rectangular grooves 7 of the first support body 2 and the rectangular grooves 7 of the second support body 3 together form an internal cavity to accommodate the depth-of-cut adjustment gear 6.

[0141] In order to enable the first carrier 2 and the second carrier 3 to move up and down in the rectangular through groove 101 of the tool holder 1, the bottom surface of the rectangular groove 7 is a toothed surface, which can mesh with the depth of cut adjustment gear 6.

[0142] To facilitate the application of external force, the adjustment mechanism also includes a rotating shaft. One end of the rotating shaft is connected to the depth-of-cut adjustment gear 6, and the other end is connected to the drive assembly mounted on the tool holder 1. There can be two rotating shafts, one at each end of the depth-of-cut adjustment gear 6.

[0143] The aforementioned drive assembly includes a drive shaft meshing with a rotating shaft at one end and a drive motor assembly for controlling the rotation of the drive shaft. The two planar ends of the depth-of-cut adjustment gear 6 are slidably connected to the side end faces of the rectangular groove 7.

[0144] When the depth of cut needs to be adjusted, the drive assembly is activated, and the depth of cut adjustment gear 6 rotates under the action of the drive assembly. In the initial state, the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are flush. If the depth of cut adjustment gear 6 rotates clockwise, the first carrier 2 drives the first ball-end cutting edge 4 away from the inner wall of the titanium alloy casting chamber 11, and the second carrier 3 drives the second ball-end cutting edge 5 closer to the inner wall of the titanium alloy casting chamber 11, thereby realizing the adjustment of the distance difference C between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0145] Among them, when the depth of cut adjustment gear 6 rotates clockwise, the distance P1 that the first ball-end cutting edge 4 moves away from the end face of the inner cavity of the titanium alloy casting chamber 11 satisfies:

[0146] P1 = v1 * t1

[0147] Wherein, v1 is the linear velocity of the side end face when the depth of cut adjustment gear 6 rotates;

[0148] t1 is the rotation time of the depth-of-cut adjustment gear 6.

[0149] The distance P2 that the second ball-end cutting edge 5 moves close to the inner end face of the titanium alloy casting chamber 11 satisfies:

[0150] P2 = P1

[0151] therefore,

[0152] At this point, the rotation time of the depth-of-cut adjusting gear 6 is:

[0153]

[0154] In this way, the positions of the first support 2 and the second support 3 can be precisely adjusted.

[0155] Specifically, the cuboid sections at the upper ends of the first support body 2 and the second support body 3 have the same structural dimensions, and the depth-of-cut adjustment gear 6 is a cylindrical structure with a diameter w1 = w2, where w2 is the length dimension of the upper end of the first support body 2 or the second support body 3.

[0156] The dimensional conditions of the rectangular groove satisfy the following:

[0157] The depth of rectangular groove 7 is w3 = 1 / 2w2;

[0158] The sidewall length of rectangular groove 7 is w4 = 1 / 4w2;

[0159] The width of rectangular groove 7 is w5 = 2πw2.

[0160] Generally, the larger the working rake angle of a cutting edge, the sharper the edge, but the weaker its impact resistance. Current technologies typically improve machining efficiency by increasing the sharpness of the cutting edge, but this often results in a short cutting edge life, requiring frequent manual tool replacements. Furthermore, considering the uneven machining allowance of the ribs within the casting chamber, when two parallel ball-end cutting edges are used, both edges must bear the primary impact, leading to a simultaneous decrease in the lifespan of both machining tools.

[0161] Therefore, the present invention uses the working rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 that cooperate with each other, that is, the working rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are different. One ball-end cutting edge contacts the rib first. The ball-end cutting edge with a smaller working rake angle has better impact resistance and can withstand the main impact, thereby further improving the tool's service life, overall strength and cutting efficiency.

[0162] For details, see attached. Figure 3-5 As shown, the fixed rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are α1 and β1, respectively, and the installation rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are α2 and β2, respectively. The working rake angle of the first ball-end cutting edge 4 is α = α1 + α2, and the working rake angle of the second ball-end cutting edge 5 is β = β1 + β2.

[0163] The working rake angle α of the first ball end cutting edge 4 is set to be relatively small in order to bear the main impact and protect the second ball end cutting edge 5. The value of α is determined by the hardness of the titanium alloy casting 11 material and the cutting depth of the first ball end cutting edge 4. The working rake angle β of the second ball end cutting edge 5 is greater than α, that is, α < β, in order to improve its sharpness and thus improve the overall processing efficiency.

[0164] After determining the values ​​of α and β, the values ​​of α and β are adjusted by adjusting the inclination of the bottom surfaces of the first and second mounting grooves and the fixed values ​​of the rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0165] Specifically, the working rake angle α of the first ball end cutting edge 4 satisfies:

[0166]

[0167] Among them, H ⅠThe material hardness of the first ball-end cutting edge 4;

[0168] H 钛合金 The hardness of titanium alloy casting material 11;

[0169] K α This is a correction factor, with a value ranging from 16.9 to 25.9;

[0170] a represents the depth of cut of the first ball-end cutting edge 4.

[0171] Specifically, the working rake angle β of the second ball end cutting edge 5 satisfies:

[0172]

[0173] Among them, H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0174] H 钛合金 The hardness of titanium alloy casting material 11;

[0175] K β This is a correction factor, with a value range of 14.2 to 25.3;

[0176] b is the depth of cut of the second ball-end cutting edge 5.

[0177] For example, K α H is 20.33. Ⅰ For RHC70, H 钛合金 For RHC30, a is 1 mm, and α = -1.5°.

[0178] For example, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have the same shape, size, and material. In this case, H Ⅰ =H Ⅱ =RHC70; where K β Since the value is 18.08 and b = 1.1 mm, β = 0.5°.

[0179] Specifically, the fixed rake angle values ​​of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are determined by the shape of the ball-end cutting edge itself. For example, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 have the same shape. In this case, the fixed rake angle values ​​α1 and β1 of the two ball-end cutting edges satisfy: α1 = β1, specifically 1.5°. Therefore, according to the formulas α = α1 + α2 and β = β1 + β2, the installation rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 can be calculated. That is, the installation rake angle α2 of the first ball-end cutting edge 4 is α - α1 = -1.5° - 1.5° = -3°, and the installation rake angle β2 of the second ball-end cutting edge 5 is β - β1 = 0.5° - 1.5° = -1°.

[0180] After determining the mounting rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, the inclination of the bottom surface in the first mounting groove and the second mounting groove is set respectively. The bottom surface is the surface that contacts the mounting surface of the first ball-end cutting edge 4 or the second ball-end cutting edge 5. The inclination of the bottom surface is the same as the mounting rake angle of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, thereby realizing the adjustment of the mounting rake angles of the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0181] Specifically, such as Figure 7 As shown, the first carrier 2 consists of upper and lower parts. The upper part is installed in the rectangular through groove 101 inside the tool holder 1, and the lower part is screwed to the lower end of the upper part for easy replacement. The lower part of the first carrier 2 has a first mounting groove for installing the first ball-end cutting edge 4, as shown in the attached figure. Figure 4 As shown, the bottom surface of the first mounting groove has an inclination of α2. When machining the lower part of the first carrier 2, the inclination of the bottom surface is shaped to adjust the working rake angle of the first ball head cutting edge 4.

[0182] Specifically, the second support body 3 has the same structure as the first support body 2, the difference being the inclination of the bottom surface of the second mounting groove opened at the lower part of the second support body 3, the inclination of the bottom surface of the second mounting groove is β2.

[0183] Considering the small gap between the adjacent surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, for example, the gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is 3mm; during the cutting process, the existing cutting fluid supply method may not be able to reach the gap, and the end face at the gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5 cannot be cooled. In addition, chips may also enter the gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5, and may accumulate between the first ball-end cutting edge 4 and the second ball-end cutting edge 5. Excessive chip accumulation will wear down the first ball-end cutting edge 4 and the second ball-end cutting edge 5, reducing their service life.

[0184] To solve the above problems, a cleaning device can be provided to cool, lubricate and remove residual metal chips from the gap between the adjacent surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 during the cutting process.

[0185] Specifically, the cleaning device includes a first channel 9 and a second channel 10 for gas and liquid flow on the first carrier 2. Along the cutting direction, the air jet of the first channel 9 and the liquid jet of the second channel 10 are located at the rear end of the ball face of the first ball cutting edge 4 and the second ball cutting edge 5, respectively, and are arranged toward the gap between the first ball cutting edge 4 and the second ball cutting edge 5.

[0186] In order to increase the flow rate of the cutting fluid ejected from the second channel 10 to clean the debris adhering to the adjacent edge gap between the first ball-nose cutting edge 4 and the second ball-nose cutting edge 5, the present invention uses the ejected gas to increase the flow rate of the cutting fluid, thereby improving the cleaning efficiency of the debris. At the same time, by accelerating the air flow on the surfaces of the first ball-nose cutting edge 4 and the second ball-nose cutting edge 5, the cooling effect on the double-tangent tool is improved.

[0187] Specifically, along the cutting forward direction, the air jet outlet of the first channel 9 is arranged at the lower end of the liquid jet outlet of the second channel 10. Among them, air or nitrogen is used to flow in the first channel 9, and cutting fluid is used to flow in the second channel 10. The diameter of the air jet outlet of the first channel 9 is x1, and the diameter of the liquid jet outlet of the second channel 10 is x2. Among them, 1 / 3*R1 < x1 = x2 < 1 / 2*R1, that is, 1mm < x1 = x2 < 1.5mm, and x1 = x2 = 1.4mm is set; among them, the air outlet rate of the air jet outlet of the first channel 9 is 8 - 10m / s; the liquid outlet rate of the liquid jet outlet of the second channel 10 is 0.25 - 0.3m / s. In this way, the ejected gas increases the cutting fluid towards the gap between the first ball-nose cutting edge 4 and the second ball-nose cutting edge 5, so as to improve the effects of cooling, lubricating the cutting edge in the gap and removing residual metal debris.

[0188] In order to enable the first channel 9 to stably eject gas and enable the second channel 10 to stably eject cutting fluid, the present invention provides a gas supply device and a liquid supply device outside the first carrier 2. Specifically, the air inlet end of the first channel 9 is connected to the gas supply device arranged outside the first carrier 2, and the gas supply device includes an air delivery pipe for delivering air or nitrogen into the first channel 9. The liquid inlet of the second channel 10 is connected to the liquid supply device, and the liquid supply device includes an infusion pipeline for delivering cutting fluid into the second channel 10.

[0189] Furthermore, in order to better implement the above-mentioned double-tangent machining method for titanium alloy casting cabins, the present invention also provides a double-tangent machining device. The double-tangent machining device includes the above-mentioned double-tangent tool, and also includes a tool bar 17 fixedly connected to the tool holder 1 at one end. The other end of the tool bar 17 is fixedly arranged in the base 18, and the base 18 is installed on the Z-axis support plate of the machine tool. In this way, the machine tool Z-axis support plate controls the base 18 to drive the tool bar 17 to move, and further drives the double-tangent tool to move in the direction of the Z-axis support plate movement to perform cutting operations.

[0190] Specifically, the parameters of the tool bar 17 satisfy:

[0191] Diameter E = 0.35*E1;

[0192] Length L = L1 + 5; [[ID=2))

[0193] Strength coefficient

[0194] Wherein, E1 is the inner diameter of the titanium alloy casting chamber 11;

[0195] L1 is the depth of the inner cavity of the titanium alloy casting chamber 11.

[0196] For example, E1 = 760mm, L1 = 920mm, at this time, It can be seen that t≤5, which belongs to a high-strength system, and the strength of tool holder 17 can meet the cutting requirements.

[0197] To improve the stability of the cutting process, a clamping fixture is also provided. The clamping fixture includes two clamping parts for fixing the titanium alloy casting chamber 11, which are used to clamp the titanium alloy casting chamber 11 axially to ensure the stability of the titanium alloy casting chamber 11 during cutting, thereby improving the cutting efficiency.

[0198] Specifically, the clamping fixture includes an upper ring 19 and a lower ring 20 fixedly connected to the upper ring 19 via a screw 21. The upper ring 19 is fixed to the end face of the machine tool chuck and is used to hold the titanium alloy casting chamber 11. The lower ring 20 is fixedly connected to the upper ring 19 via the screw 21 and clamps the titanium alloy casting chamber 11 between the upper ring 19 and the lower ring 20, thereby axially pressing the titanium alloy casting chamber 11. Thus, through this clamping fixture, the clamping force is concentrated in the axial direction, reducing the radial force on the titanium alloy casting chamber 11, which can greatly reduce the clamping deformation of the titanium alloy casting chamber 11 and improve the stable cutting control of the titanium alloy casting chamber 11.

[0199] To further improve the stability of clamping the titanium alloy casting 11, the upper ring 19 and the lower ring 20 are provided with a stop with a clearance of 0.1mm from the outer shape of the titanium alloy casting 11, so as to restrict the five degrees of freedom of the titanium alloy casting 11 in the X, Y, Z, A and B directions.

[0200] Specifically, to facilitate the clamping of the titanium alloy casting housing, the parameters of the upper ring 19 meet the following requirements:

[0201] Inner diameter j1=0.9E1;

[0202] Outer diameter j2 = 1.2E1.

[0203] The parameters of the lower ring 20 satisfy:

[0204] Inner diameter j3=0.97E1;

[0205] Outer diameter J4 = 1.2E1.

[0206] The parameters of screw 21 satisfy:

[0207] Length g = 1.1L1.

[0208] Specifically, four screws 21 are provided, evenly distributed between the upper ring 19 and the lower ring 20. Each end of the screw 21 has a matching nut, which secures the upper ring 19 and the lower ring 20 by engaging the screws 21 with the nuts. For example, the nut is a GBT6170 nut M20, and a torque wrench is used to tighten it.

[0209] The torque value M of the torque wrench is set to 45±3 N·m. During the tightening of the nut using the torque wrench, the torque wrench emits a "click" sound to indicate that the set torque value has been reached. The tightening torque f1 of the nut satisfies:

[0210]

[0211] Among them, T 扭矩 =M = 45 ± 3 N·m;

[0212] K 扭矩 The torque coefficient corresponding to this nut is 0.15;

[0213] d 螺杆 The diameter of the end where the screw 21 mates with the nut is 0.020 μm.

[0214] at this time, The total clamping force f of the four nuts on the lower ring 20 总 =4f1=60~64KN.

[0215] For example, a resistance force gauge is used to measure the turning force f. 车削 Measurements were taken during the turning process, f 车削 The resistance is consistently less than 55 kN, which is visually demonstrated by the fact that the titanium alloy casting chamber 11 remains in a stable clamping state during the machining process.

[0216] For example, the external dimensions of the titanium alloy casting chamber 11 are measured by laser scanner or dial indicator. Before clamping, the inner diameter depth of the titanium alloy casting chamber 11 is L1 = 1m; after clamping, the inner diameter depth of the titanium alloy casting chamber 11 is L2 = 1.02m; L2-L1 = 0.02 < 0.05. It can be seen that the mechanical properties of the clamping fixture meet the requirements during the turning process. At the same time, the clamping results in a small deformation of the titanium alloy casting chamber 11, which meets the processing requirements.

[0217] To further improve the service life of dual-point cutting tools, a cutting fluid feeding device is also provided. This cutting fluid feeding device includes a cutting fluid delivery pipe for conveying cutting fluid along the cutting direction to cool, lubricate, and remove larger chips from the ball face of the first ball cutting edge 4 and the second ball cutting edge 5.

[0218] Specifically, along the cutting direction, the outlet of the cutting fluid delivery pipe is positioned at the gap between the cutting surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5. The outlet diameter of the cutting fluid delivery pipe is X3 = 5 / 4D, and the cutting fluid flow velocity at the outlet is 0.2-0.3 m / s. During cutting, the cutting fluid contacts the ball-end surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5, then flows downwards through the side ends of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 to the side end faces; additionally, a small portion of the cutting fluid flows into the gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5.

[0219] To achieve stable cutting fluid ejection from the cutting fluid delivery pipe, the cutting fluid feeding device includes a cutting fluid storage device for delivering cutting fluid into the cutting fluid delivery pipe, so as to stably deliver cutting fluid into the cutting fluid delivery pipe.

[0220] During operation, the clamping fixture drives the titanium alloy casting chamber 11 to rotate at a speed of 29-37 r / min; the machine tool Z-axis support plate control base 18 drives the tool holder 17 to move, thereby driving the double-point cutting tool to move in the direction of the Z-axis support plate, so that the double-point cutting tool can be axially fed or unfurled at a speed of 0.1-0.2 mm / r; during cutting, along the cutting direction, the cutting fluid feeding device cools, lubricates and removes chips from the ball face of the first ball cutting edge 4 and the second ball cutting edge 5, so as to cooperate with the cleaning device to achieve efficient cooling, lubrication and chip removal of the first ball cutting edge 4 and the second ball cutting edge 5 in all directions.

[0221] Compared with the prior art, the dual-cutting-point machining method of the present invention uses two ball-end cutting edges that are flush with each other but have uneven lower edges to cut along the cutting direction. The depth of cut of one machining trajectory is the sum of the depths of cut of the two ball-end cutting edges, which improves machining efficiency. During cutting, two ball-end cutting edges with different working rake angles are used to reduce the impact of uneven machining allowance ribs in the inner cavity of the titanium alloy casting on the tool life. That is, a ball-end cutting edge with a smaller working rake angle is used to bear the main impact, and a ball-end cutting edge with a larger working rake angle is used to ensure the overall sharpness of the tool. In this way, the tool life is improved and the machining efficiency is improved.

[0222] The tool used in this invention is a double-point offset tool composed of two ball-end cutting edges, that is, both ball-end cutting edges participate in cutting, and the distance difference between the cutting ends of the two ball-end cutting edges is not equal to 0. In this way, the depth of cut of the machine tool in one machining trajectory is the sum of the depths of cut of the two ball-end cutting edges, which improves the efficiency of single cutting. In addition, by setting the working rake angle combination of the two ball-end cutting edges, that is, α < β, the overall sharpness of the machining tool is improved while ensuring the overall impact resistance of the machining tool, thereby improving the machining efficiency.

[0223] The relative positions of the first support body 2 and the second support body 3 can be adjusted by adjusting the depth of cut gear 6, thereby precisely adjusting the depth of cut of the ball end cutting edge and adjusting the position of each cutting edge relative to the inner cavity of the titanium alloy casting chamber 11 during the machining process. In this way, reciprocating cutting can be achieved on the one hand, and the side wall of the inner cavity of the titanium alloy casting chamber 11 near the upper ring 19 can be cut on the other hand, so as to achieve all-round machining of the inner cavity of the titanium alloy casting chamber 11 without dead angles, thereby improving the machining efficiency.

[0224] The dual-cutting-point machining method of the present invention can improve the tool life and avoid frequent tool replacement, thereby improving machining efficiency. The machining time of a single titanium alloy casting chamber 11 inner cavity can be as low as 4.5 hours, which is about twice the machining efficiency compared with the prior art.

[0225] When machining the inner cavity of the titanium alloy casting chamber 11, this invention uses two ball-end cutting edges to share the machining amount, reducing the machining amount borne by a single cutting edge. Compared with the prior art, when machining a single part, the wear borne by a single cutting edge is reduced, thus improving the life of the machining tool. In addition, one ball-end cutting edge bears the main impact with a smaller working rake angle, protecting the other ball-end cutting edge. That is, in the initial state, the machining allowance of the ribs in the inner cavity of the titanium alloy casting chamber 11 is uneven. One ball-end cutting edge contacts the ribs first. The ball-end cutting edge with a smaller working rake angle has better impact resistance and bears the main impact. The end face of the ball-end cutting edge after machining is a uniform end face, avoiding the phenomenon of local discontinuous cutting caused by the uneven end face, thereby reducing the impact on the other ball-end cutting edge and thus improving the service life of the machining tool.

[0226] The cutting fluid ejection channel and gas ejection channel set on the first carrier 2 can be used to cool and lubricate the gap between the cutting edges, which solves the problem that the existing cutting fluid supply method may not be able to reach the gap. This achieves all-round cooling and lubrication of the cutting edge. At the same time, it can remove the debris adhering to the gap between the cutting edges and avoid debris friction on the cutting edge. This further improves the service life of the tool. The service life of a single cutting edge is as low as 8.2 hours, which is 16.4-24.6 times higher than the existing technology.

[0227] Both ball-end cutting edges of the present invention can be circular blades, and the working rake angle of each angle of the circular blade is the same. Therefore, when the cutting end of the blade breaks, it is only necessary to rotate the circular blade, and the unbroken part can continue to cut with the original depth of cut and working rake angle. The utilization rate of a single blade is improved, the cost is reduced, and there is no need to adjust the depth of cut and working rake angle during the installation process, which improves the installation efficiency and thus improves the overall processing efficiency.

[0228] Example 1:

[0229] A method for machining the inner cavity of a titanium alloy casting chamber using two cutting points includes the following steps:

[0230] S101: Using clamping fixtures, the titanium alloy casting chamber 11 is pressed axially.

[0231] Specifically, the upper ring 19 is fixed to the end face of the machine tool chuck, and one end of the titanium alloy casting chamber 11 is placed inside the stop of the upper ring 19; then the stop of the lower ring 20 is clamped on the other end face of the titanium alloy casting chamber 11, and the lower ring 20 is fixedly connected to the upper ring 19 by the cooperation of the screw 21 and the nut, so as to restrict the five degrees of freedom of the titanium alloy casting chamber 11 in the X, Y, Z, A and B directions.

[0232] Among them, the inner diameter of the upper ring 19 is j1 = 0.9E1 = 684 mm, and the outer diameter of the upper ring 19 is j2 = 1.2E1 = 912 mm; the inner diameter of the lower ring 20 is j3 = 0.97E1 = 737.2 mm, and the outer diameter of the lower ring 20 is j4 = 1.2E1 = 912 mm; the length of the screw 21 is g = 1.1L1 = 1012 mm.

[0233] S102: Connect the dual-point cutting tool to a device for controlling the feed or discharge of the tool.

[0234] Specifically, the tool holder 1 of the double-cutting-point tool is fixedly connected to the tool shank 17, and the other end of the tool shank 17 is fixedly set in the base 18, which is mounted on the Z-axis support plate of the machine tool. Thus, the base 18 is controlled by the Z-axis support plate of the machine tool to drive the tool shank 17 to move, thereby driving the double-cutting-point tool to move in the direction of the Z-axis support plate to perform cutting operations.

[0235] The diameter of the tool holder 17 is E = 0.35 * E1 = 0.35 × 760 = 266 mm; the length of the tool holder 17 is L = L1 + 5 = 920 + 5 = 925 mm.

[0236] S103: Set the tool feed position and adjust the tool status.

[0237] Specifically, taking the horizontal line parallel to the machine tool as the X-axis, the vertical line perpendicular to the X-axis as the Y-axis, the center of one end of the titanium alloy casting chamber 11 as the zero point, and the surface parallel to the inner cavity port at the top of the titanium alloy casting chamber 11 as the coordinate axis surface, the tool feeding position is at the lower left 45° position of the inner cavity port of the titanium alloy casting chamber 11, that is, at -135°.

[0238] Specifically, adjust the first support body 2 and the second support body 3 to be perpendicular to the end face of the feed position; and rotate the depth of cut adjustment gear 6 clockwise for a period of time. This makes the distance between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 1.1mm.

[0239] S104: Adjust the state of the titanium alloy casting chamber and move the double-point cutting tool to the tool feeding position.

[0240] Specifically, the machine tool controls the chuck to rotate counterclockwise at a speed of 34 r / min, thereby driving the inner cavity of the titanium alloy casting chamber 11 to rotate counterclockwise; and the Z-axis support plate controls the movement of the tool holder 17 to move the double-cutting point tool to the tool feeding position.

[0241] S105: The inner cavity of the titanium alloy casting chamber is machined using a double-cutting-point tool.

[0242] Specifically, during machining, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 feed at a speed of 0.1 mm / r.

[0243] Specifically, during the initial machining of the inner cavity of the titanium alloy casting chamber 11, the first ball-end cutting edge 4 first cuts the inner cavity of the titanium alloy casting chamber 11. At this time, the second ball-end cutting edge 5 is in an idle state for a period of time. Then, the tool is fed axially. During this process, the second ball-end cutting edge 5 cuts the surface processed by the first ball-end cutting edge 4. At this time, the depth of cut of a machining trajectory is Y = a + b, which greatly improves the machining efficiency.

[0244] When the first ball-end cutting edge 4 moves axially to the inner cavity at the bottom of the titanium alloy casting chamber 11, the distance between the first ball-end cutting edge 4, the second ball-end cutting edge 5 and the inner cavity of the titanium alloy casting chamber 11 is adjusted by the adjustment mechanism to process the inner cavity at the bottom of the titanium alloy casting chamber 11.

[0245] Specifically, the depth-of-cut adjusting gear 6 is rotated counterclockwise for a period of time. At this point, the first ball-end cutting edge 4 continues cutting, with a depth of cut of v1*t3; after a period of time Then, continue to rotate the depth-of-cut adjusting gear 6 counterclockwise. The rotation time of the depth-of-cut adjusting gear 6 is... At this time, the first ball-end cutting edge 4 continues to cut, with a cutting depth of v1*t5; thus, the first ball-end cutting edge 4 is used to cut the inner cavity at the bottom of the titanium alloy casting 11. Finally, the surface finally machined by the first ball-end cutting edge 4 is flush with the surface finally machined by the second ball-end cutting edge 5.

[0246] Specifically, after the final machined surfaces of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are flush, the first and second ball-end cutting edges 4 and 5 are engaged at a speed of 0.1 mm / r to machine the inner cavity of the titanium alloy casting chamber 11. At this time, the depth of cut of the first and second ball-end cutting edges 4 and 5 remains unchanged, and the distance between the lower edges of the first and second ball-end cutting edges 4 and 5 is adjusted to 'a', meaning the first ball-end cutting edge 4 is closer to the inner wall of the titanium alloy casting chamber 11 than the second ball-end cutting edge 5. During the adjustment of the depth of cut of the first ball-end cutting edge 4 to 'a', the first ball-end cutting edge 4 first cuts the inner cavity at the bottom of the titanium alloy casting chamber 11, while the second ball-end cutting edge 5 is in an unloaded state.

[0247] The positions of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are continuously adjusted by the machine tool so that the depth of cut of the second ball-end cutting edge 5 reaches b. During the adjustment of the depth of cut of the second ball-end cutting edge 5 to b, the speed at which the double-point cutting tool moves perpendicular to the inner cavity of the titanium alloy casting chamber 11 is 0.1 mm / r.

[0248] When the depth of cut of the second ball end cutting edge 5 reaches b, the depth of cut of the first ball end cutting edge 4 in the inner cavity at the bottom of the titanium alloy casting chamber is a+b. When the depth of cut of the second ball end cutting edge 5 reaches b, the tool holder 17 drives the first ball end cutting edge 4 and the second ball end cutting edge 5 to start exiting at a speed of 0.1mm / r through the Z-axis support plate. At this time, the depth of cut of a machining trajectory is Y=a+b, which greatly improves the machining efficiency.

[0249] Among them, the depth of cut of the first ball-end cutting edge 4 Its working front angle Its installation front angle α2 = α - α1 = -1.5° - 1.5° = -3°;

[0250] Among them, the depth of cut of the second ball-end cutting edge 5 Its working front angle Its installation front angle β2 = β - β1 = 0.5° - 1.5° = -1°.

[0251] During axial feed cutting, the distance C between the lower edges of the second ball-end cutting edge 5 and the first ball-end cutting edge 4 is 1.1 mm; during axial discharge cutting, the distance C between the lower edges of the second ball-end cutting edge 5 and the first ball-end cutting edge 4 is 1 mm. The gap between adjacent edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is 3 mm. The depth of cut Y = a + b = 2.1 mm for one machining path.

[0252] Wherein, w1=w2=20mm, the groove depth of rectangular groove 7 is w3=1 / 2w2=10mm; the side wall length of rectangular groove 7 is w4=1 / 4w2=5mm; the width of rectangular groove 7 is w5=2πw2=126mm; in the initial state, the bottoms of the first ball end cutting edge 4 and the second ball end cutting edge 5 are flush.

[0253] Among them, one end face of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is a mounting surface, which is screwed into the first mounting groove and the second mounting groove respectively. The other end face is a convex surface, and the end of the convex surface is a circular cutting edge. A groove is provided in the middle of the convex surface. During installation, the head of the screw is located in the groove, and the shank of the screw is fixedly connected to the first mounting groove or the second mounting groove through the mounting surface.

[0254] S106: During the cutting process, the cutting fluid supply device is used to cool, lubricate and remove chips from the double-cutting-point tool. At the same time, the air supply device and the liquid supply device are activated to cool, lubricate and remove chips from the gap between the first ball-end cutting edge and the second ball-end cutting edge.

[0255] Specifically, the outlet diameter X3 = 5 / 4D = 15mm, and the cutting fluid flow rate at the outlet is 0.3m / s.

[0256] Specifically, x1 = x2 = 1.4 mm; where the air velocity of the jet nozzle of the first channel 9 is 10 m / s; and the liquid velocity of the liquid nozzle of the second channel 10 is 0.3 m / s.

[0257] Using this method, the processing time for a single piece is 4.5 hours, the service life of the first ball-end cutting edge 4 is 8.2 hours, and the service life of the second ball-end cutting edge 5 is 8.8 hours.

[0258] Comparative Example 1:

[0259] A method for machining the inner cavity of a titanium alloy casting chamber, which differs from Example 1 in that...

[0260] Comparative Example 1 uses a ball-end cutting edge to reciprocate cut the inner cavity of a titanium alloy casting chamber. The depth of cut of the ball-end cutting edge is fixed at 1 mm, the depth of cut for one machine tool movement is 1 mm, and the working rake angle of the ball-end cutting edge is fixed at 1°.

[0261] The machining tool was used to machine the inner cavity of the titanium alloy casting chamber. The machining time for a single piece was 8.5 hours, and the service life of the ball end cutting edge was 20-30 minutes.

[0262] Compared with Comparative Example 1, the present invention significantly improves processing efficiency, tool life, and reduces manual intervention. See below for details.

[0263] Table 1. Processing effects of Example 1 and Comparative Example 1

[0264]

[0265]

[0266] As shown in Table 1, the processing time for a single part in this invention is 4.5 hours, which is much shorter than the processing time of 8.5 hours for a single part in Comparative Example 1. This demonstrates that the dual-cutting-point processing method of this invention can significantly improve processing efficiency.

[0267] During the processing, the continuous processing time of the cutting edge of the present invention is not less than 8.2 hours and can reach up to 8.8 hours, which is much higher than the continuous processing time of 20-30 minutes of the cutting edge in Comparative Example 1. It can be seen that the dual-cutting point processing method of the present invention can significantly improve the service life of the cutting tool, eliminate the need to replace the cutting tool during the processing, improve processing efficiency, and reduce the human intervention rate.

[0268] Therefore, the present invention utilizes the above-mentioned dual-cutting point machining method to perform intermittent and efficient turning machining on the inner cavity of the titanium alloy casting chamber, which can effectively solve the problem of frequent impact of parts on the tool, resulting in rapid tool chipping or wear, and can also effectively improve the cutting efficiency.

[0269] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for machining a titanium alloy pod cavity double tangent point, characterized in that: The method comprises synchronously cutting the inner cavity of the titanium alloy casting cabin by using the first ball head cutting edge and the second ball head cutting edge. During the cutting, the lower edges of the first ball head cutting edge and the second ball head cutting edge are not flush, and along the cutting direction, the first ball head cutting edge and the second ball head cutting edge are flush. The lower end of the first bearing body is provided with a first mounting groove for mounting the first ball head cutting edge, and the lower end of the second bearing body is provided with a second mounting groove for mounting the second ball head cutting edge. The inclination of the bottom surface of the first mounting groove and the fixed value of the rake angle of the first ball head cutting edge are equal to the working rake angle of the first ball head cutting edge. The inclination of the bottom surface of the second mounting groove and the fixed value of the rake angle of the second ball head cutting edge are equal to the working rake angle of the second ball head cutting edge. The working rake angle β of the second ball head cutting edge is greater than the working rake angle α of the first ball head cutting edge. During the cutting, the cutter cuts along the circumference of the inner cavity of the titanium alloy casting cabin and advances axially along the axis of the inner cavity of the titanium alloy casting cabin. After cutting along the circumference of the inner cavity of the titanium alloy casting cabin for one turn, a circumferential machining track is formed. The second ball head cutting edge cuts on the previous machining track formed by the first ball head cutting edge.

2. The dual intersection machining method of claim 1, wherein: During the cutting, the cutting depth a of the first ball head cutting edge satisfies: Wherein, H Ⅰ is the material hardness of the first ball head cutting edge; H 钛合金 is the hardness of the titanium alloy casting cabin material; K a is a correction coefficient, the value range is 3.0-8.9; D is the diameter of the first ball head cutting edge, the value range is 6-12 mm; The cutting depth b of the second ball head cutting edge satisfies: wherein H Ⅱ is the material hardness of the second ballnose cutting edge; H 钛合金 is the hardness of the titanium alloy material of the cast cabin; K b is a correction coefficient, with a value range of 2.6-8.9; and D is the diameter of the second ballnose cutting edge, with a value range of 6-12 mm. The cutting depth of one machining track is the sum of the cutting depths of the first ball head cutting edge and the second ball head cutting edge.

3. The method of claim 1 wherein: During the cutting, the working rake angle α of the first ball head cutting edge satisfies: wherein H Ⅰ is the material hardness of the first ball nose cutting edge; H 钛合金 is the hardness of the titanium alloy cast cabin material; K α is a correction coefficient, with a value range of 16.9-25.9; and a is the cutting depth of the first ball nose cutting edge.

4. A method of two-point machining according to claim 3, wherein: During the cutting, the working rake angle β of the second ball head cutting edge satisfies: wherein H Ⅱ is the material hardness of the second ballnose cutting edge; H 钛合金 is the hardness of the titanium alloy cast cabin material; K β is a correction coefficient, with a value range of 14.2-25.3; and b is the cutting depth of the second ballnose cutting edge.

5. The method of claim 1 wherein: The first ball head cutting edge and the second ball head cutting edge advance axially or retreat axially along the axis of the inner cavity of the titanium alloy casting cabin to perform circumferential cutting. During the cutting, the cutting direction at any time is perpendicular to the axial advancement or retreat direction of the first ball head cutting edge and the second ball head cutting edge.

6. A method of two-point machining according to claim 5, wherein: When advancing axially, the distance between the lower edges of the first ball head cutting edge and the second ball head cutting edge is the same as the cutting depth of the second ball head cutting edge. When retreating axially, the distance between the lower edges of the first ball head cutting edge and the second ball head cutting edge is the same as the cutting depth of the first ball head cutting edge.

7. A method of two-point machining according to claim 6, wherein: When advancing axially, when the first ball head cutting edge is machined to the inner cavity near the bottom of the titanium alloy casting cabin, the distance between the first ball head cutting edge, the second ball head cutting edge and the inner cavity of the titanium alloy casting cabin is adjusted by using the adjusting mechanism to machine the inner cavity at the bottom of the titanium alloy casting cabin.

8. A two-point machining method according to one of claims 1 to 7, characterized in that: During the cutting, along the cutting direction, the first channel and the second channel are controlled to spray gas and cutting fluid respectively to cool, lubricate and remove debris at the gap between the adjacent surfaces of the first ball head cutting edge and the second ball head cutting edge.

9. The method of claim 1 wherein: During the cutting, the titanium alloy casting cabin rotates counterclockwise at a speed of 29-37 r / min.

10. The method of claim 4 wherein: The speed of the axial advancement or retreat of the first ball head cutting edge and the second ball head cutting edge is 0.1-0.2 mm / r.

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