Titanium alloy cabin inner cavity multi-cutting point processing method

Abstract

The present application relates to a kind of titanium alloy casting cabin inner cavity multi-cutting point processing method, belong to turning, the problem of frequent impact tool in prior art of part, leading to tool rapid collapse blade or wear is solved.The multi-cutting point processing method of the present application includes using first ball head cutting edge, second ball head cutting edge, third ball head cutting edge and fourth ball head cutting edge to carry out synchronous cutting to titanium alloy casting cabin inner cavity;Wherein, when cutting, the lower edge of the first ball head cutting edge, second ball head cutting edge, third ball head cutting edge and fourth ball head cutting edge is not flush;And along the direction of cutting advance, the first ball head cutting edge is flush with third ball head cutting edge, and the second ball head cutting edge is flush with fourth ball head cutting edge.Implementation in intermittent machining process improves the service life of tool, and improves processing efficiency.

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 multiple 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 multi-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 multi-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 using a first ball-end cutting edge, a second ball-end cutting edge, a third ball-end cutting edge, and a fourth ball-end cutting edge.

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

[0007] Based on a further improvement of the above method, during cutting, 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 second ball-end cutting edge;

[0008] Wherein, the depth of cut 'a' of the first ball-end cutting edge satisfies:

[0009]

[0010] 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.

[0011] The depth of cut b of the second ball-end cutting edge satisfies:

[0012]

[0013] 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 correction factor is 2.5 to 8.9; D is the diameter of the second ball end cutting edge, ranging from 6 to 12 mm.

[0014] Based on a further improvement of the above method, during cutting, the distance between the lower edges of the third ball-end cutting edge and the fourth ball-end cutting edge is the same as the depth of cut of the fourth ball-end cutting edge;

[0015] Wherein, the depth of cut c of the third ball-end cutting edge satisfies:

[0016]

[0017] Among them, H Ⅲ H represents the material hardness of the third ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K c The value is a correction factor, ranging from 2.6 to 8.9; D is the diameter of the third ball end cutting edge, ranging from 6 to 12 mm.

[0018] The depth of cut d of the fourth ball-end cutting edge satisfies:

[0019]

[0020] Among them, H Ⅳ H represents the material hardness of the fourth ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K d The value is a correction factor, ranging from 2.4 to 7.1; D is the diameter of the fourth ball end cutting edge, ranging from 6 to 12 mm.

[0021] During axial feed, the distance between the lower edge of the second ball-end cutting edge and the lower edge of the third ball-end cutting edge is the same as the depth of cut of the third ball-end cutting edge.

[0022] Based on further improvements to the above method, a trajectory depth of cut is the sum of the depths of cut of the first ball-end cutting edge, the second ball-end cutting edge, the third ball-end cutting edge, and the fourth ball-end cutting edge.

[0023] Based on a further improvement of the above method, during cutting, the working rake angle of the first ball-end cutting edge is smaller than that of the second ball-end cutting edge;

[0024] Wherein, the working rake angle α of the first ball end cutting edge satisfies:

[0025]

[0026] 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;

[0027] The working rake angle β of the second ball end cutting edge satisfies:

[0028]

[0029] 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 13.1 to 25.0; b is the depth of cut of the second ball end cutting edge.

[0030] Based on a further improvement of the above method, during cutting, the working rake angle of the third ball-end cutting edge is between the working rake angles of the first ball-end cutting edge and the second ball-end cutting edge, and the working rake angle of the fourth ball-end cutting edge is greater than the working rake angle of the second ball-end cutting edge.

[0031] Wherein, the working rake angle γ of the third ball-end cutting edge satisfies:

[0032]

[0033] Among them, H Ⅲ H represents the material hardness of the third ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K γ is a correction factor, with a value range of 14.2 to 25.3; c is the depth of cut of the third ball end cutting edge;

[0034] The working rake angle δ of the fourth ball-end cutting edge satisfies:

[0035]

[0036] Among them, H Ⅳ H represents the material hardness of the fourth ball-end cutting edge. 钛合金 The hardness of the titanium alloy casting material; K δThe value is a correction factor, ranging from 12.5 to 19.6; d is the depth of cut of the fourth ball end cutting edge.

[0037] Based on further improvements to the above method, the first ball-end cutting edge, the second ball-end cutting edge, the third ball-end cutting edge and the fourth ball-end cutting edge make circumferential cutting by feeding into the inner cavity of the titanium alloy casting chamber along the axial direction.

[0038] During cutting, the cutting direction at any given moment is perpendicular to the axial feed direction of the first ball-end cutting edge, the second ball-end cutting edge, the third ball-end cutting edge, or the fourth ball-end cutting edge.

[0039] Based on further improvements to the above method, during cutting, a cleaning device is used to cool, lubricate, and remove debris from the gaps between adjacent surfaces of the first, second, third, and fourth ball-end cutting edges along the cutting direction.

[0040] Based on a further improvement of the above method, during cutting, 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 an adjustment mechanism to machine the inner cavity at the bottom of the titanium alloy casting chamber.

[0041] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0042] 1. The multi-point machining method of the present invention uses two pairs of four ball-end cutting edges, which are arranged parallel to each other but 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 four ball-end cutting edges, which improves machining efficiency. During cutting, the four ball-end cutting edges with different working rake angles reduce the impact of the uneven machining allowance ribs in the inner cavity of the titanium alloy casting on the tool life. That is, one ball-end cutting edge with a smaller working rake angle is used to bear the main impact to protect the other three ball-end cutting edges, and two ball-end cutting edges with larger working rake angles are used to ensure the overall sharpness of the tool. In this way, the tool life is improved and the machining efficiency is improved.

[0043] 2. The machining tool of the present invention is a multi-point staggered tool composed of four ball-end cutting edges, that is, the four ball-end cutting edges cut synchronously, and the distance difference between the lower edges of the four ball-end cutting edges is not equal to 0. Thus, the depth of cut of the machine tool running one machining trajectory is the sum of the depths of cut of the four ball-end cutting edges, which improves the efficiency of single cutting. In addition, by setting the working rake angle combination of the four ball-end cutting edges, that is, α<γ<β<δ, the overall sharpness of the machining tool is improved while ensuring the overall impact resistance of the tool, thereby improving the machining efficiency.

[0044] 3. The relative positions of the first and second carriers can be adjusted by adjusting the depth of cut gear, thereby precisely adjusting the depth of cut of the first and third ball-end cutting edges, 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, the inner cavity at the bottom of the titanium alloy casting chamber can be cut, so as to achieve all-round machining of the inner cavity of the titanium alloy casting chamber without dead angles, thereby improving the machining efficiency.

[0045] 4. The processing tools of the present invention have a long service life, thereby avoiding frequent tool replacement and improving processing efficiency. The processing time for a single titanium alloy casting chamber cavity can be as low as 3.2 hours, which is about 1.7 times higher than the prior art.

[0046] 5. When machining the inner cavity of a titanium alloy casting chamber, this invention uses four ball-end cutting edges to distribute 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 on 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 three ball-end cutting edges. 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 good 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 three ball-end cutting edges and thus improving the service life of the machining tool.

[0047] 6. When machining the inner cavity of a titanium alloy casting, the first ball-end cutting edge bears the main impact with a small working rake angle. Along the cutting direction, the second ball-end cutting edge, located behind the first ball-end cutting edge, bears a smaller impact. Since the two are close together, they can be considered as continuous cutting, further reducing the impact on the second ball-end cutting edge. Because the first ball-end cutting edge bears the impact of the uneven ribs, the third ball-end cutting edge avoids the phenomenon of local discontinuous cutting on the uneven end face. Along the cutting direction, the fourth ball-end cutting edge, located behind the third ball-end cutting edge, bears a smaller impact. Since the fourth ball-end cutting edge is close to the third ball-end cutting edge, it can be considered as continuous cutting, further reducing the impact on the fourth ball-end cutting edge. This further improves the service life of the machining tool.

[0048] 7. The cutting fluid spray channel and gas spray channel set on the first carrier 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 machining tool. The service life of a single cutting edge is as low as 8.7 hours, which is 17.4-26.1 times higher than the existing technology.

[0049] 8. All four 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 perform cutting operations 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.

[0050] 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 what is particularly pointed out in the description and drawings. Attached Figure Description

[0051] 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.

[0052] Figure 1 This is a flowchart of the multi-point machining method for titanium alloy castings in this invention;

[0053] Figure 2 This is a schematic diagram of the cooperation structure between the multi-point cutting tool and the titanium alloy casting chamber in the axial feed direction of the present invention;

[0054] Figure 3 This is a schematic diagram of the cooperation structure between the multi-point cutting tool and the titanium alloy casting chamber in the cutting direction of the present invention;

[0055] 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;

[0056] 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, the third ball-end cutting edge, the fourth ball-end cutting edge and the tool holder in the cutting forward direction of the present invention.

[0057] Figure 6 This is a schematic diagram of the mating structure of the first ball-end cutting edge and the second ball-end cutting edge in the axial feed direction of the present invention;

[0058] Figure 7 This is a schematic diagram of the mating structure of the third and fourth ball-end cutting edges in the axial feed direction of the present invention.

[0059] Figure 8 This is a schematic diagram of the cooperation structure of the first ball-end cutting edge, the second ball-end cutting edge, the third ball-end cutting edge and the fourth ball-end cutting edge in the cutting forward direction in this invention;

[0060] Figure 9 This is a cross-sectional view of the first support body, the second support body, and the tool holder in this invention.

[0061] Figure 10 for Figure 9 Schematic diagram of the cross section at point AA;

[0062] Figure 11 for Figure 10 A schematic diagram of the mating structure of the first and second load-bearing bodies at the mid-section;

[0063] Figure 12 This is a schematic diagram of the tool holder structure in this invention;

[0064] Figure 13 This is a schematic diagram of the processing device in this invention.

[0065] Figure label:

[0066] 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-Third ball end cutting edge; 7-Fourth ball end cutting edge; 8-First auxiliary support body; 9-Second auxiliary support body; 10-Mounting screw; 11-Depth of cut adjustment gear; 12-Rectangular groove; 13-Groove; 14-First channel; 15-Second channel; 16-Titanium alloy casting chamber; 17-Direction of rotation of titanium alloy casting chamber around axis; 18-Axis of titanium alloy casting chamber; 19-Multi-point cutting tool 20 - Axial feed direction; 21 - Cutting forward direction; 22 - Force direction of the first ball-end cutting edge; 23 - Force direction of the third ball-end cutting edge; 24 - Tool holder; 25 - Base; 26 - Upper ring; 27 - Lower ring; 28 - Screw; 29 - Machining reference surface of the first ball-end cutting edge; 30 - Machining reference surface of the second ball-end cutting edge; 31 - Machining reference surface of the third ball-end cutting edge; α1 - Fixed rake angle of the first ball-end cutting edge; α2 - Mounting rake angle of the first ball-end cutting edge. C1 - Distance between the lower edges of the first and second ball-end cutting edges; C2 - Distance between the lower edges of the second and third ball-end cutting edges; C3 - Distance between the lower edges of the third and fourth ball-end cutting edges; D - Diameter of the second ball-end cutting edge; R1 - Distance between adjacent side edges of the gap between the first and third ball-end cutting edges; R2 - Distance between adjacent side edges of the second and fourth ball-end cutting edges; R3 - Distance between the lower edges of the first and second ball-end cutting edges along the feed direction. Distance; R4 - Distance between the lower edges of the third and fourth ball-end cutting edges along the feed direction; 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; c - Depth of cut of the third ball-end cutting edge with its machining reference surface as the reference; d - Depth of cut of the fourth 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 - Depth of the rectangular groove; w4 - Length of the side wall of the rectangular groove; w5 - Width of the rectangular groove. Detailed Implementation

[0067] 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.

[0068] 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.

[0069] To solve the above problems, the present invention provides a multi-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 16 using a first ball-end cutting edge 4, a second ball-end cutting edge 5, a third ball-end cutting edge 6 and a fourth ball-end cutting edge 7.

[0070] During cutting, the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are not flush; and along the cutting direction, the first ball-end cutting edge 4 and the third ball-end cutting edge 6 are flush, and the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 are flush.

[0071] In other words, during the circumferential cutting along the inner cavity of the titanium alloy casting chamber 16, the first ball-end cutting edge 4 and the third ball-end cutting edge 6 advance in parallel, and the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 advance in parallel; along the axial feed direction, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 advance in parallel, and the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 advance in parallel. The first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 have different cutting depths along the inner cavity of the titanium alloy casting chamber 16.

[0072] Compared with the prior art, along the cutting direction, the machining tool of the present invention consists of four ball-end cutting edges arranged in pairs. The ball-end surfaces of the first ball-end cutting edge 4 and the third ball-end cutting edge 6 are located in the same plane, and the ball-end surfaces of the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 are located in the same plane. Moreover, there is a height difference between the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7. That is, the distance difference between the lower edges of the four ball-end cutting edges is not equal to 0. The four cutting edges cut simultaneously, forming a tool with multiple tangent points, and performing multi-tangent point misalignment machining. During the cutting process, the tool cuts circumferentially along the inner cavity of the titanium alloy casting chamber 16 and feeds axially along the inner cavity of the titanium alloy casting chamber 16. After cutting one circumferential cycle along the inner cavity of the titanium alloy casting chamber 16, 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, the third ball-end cutting edge 6 cuts on the previous machining trajectory formed by the second ball-end cutting edge 5, and the fourth ball-end cutting edge 7 cuts on the previous machining trajectory formed by the third ball-end cutting edge 6. In this way, the depth of cut of the machine tool running one machining trajectory is the sum of the depths of cut of the four ball-end cutting edges, which improves the efficiency of single cutting. At the same time, the machining cutting amount is shared by the four ball-end cutting edges, reducing the machining amount borne by a single cutting edge. When machining a single part, the wear borne by a single cutting edge is reduced, thus improving the life of the machining tool. The machining tools have a long service life, thus avoiding frequent tool replacements and improving machining efficiency. The machining time for a single titanium alloy casting chamber with 16 internal cavities can be as low as 3.2 hours, which is about 1.7 times higher than existing technologies.

[0073] During cutting, the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are not flush, meaning there is a height difference between the lower edges of these four ball-end cutting edges. Furthermore, all four ball-end cutting edges cut simultaneously, forming a multi-point misaligned tool for multi-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', the depth of cut of the third ball-end cutting edge 6 is 'c', and the depth of cut of the fourth ball-end cutting edge 7 is 'd'. The distance between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is C1 = b > 0, the distance between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 is C2 = c > 0, and the distance between the lower edges of the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 is C3 = d > 0. The depth of cut Y for one machining trajectory is Y = a + b + c + d.

[0074] 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 four ball-end cutting edges.

[0075] Specifically, the depth of cut 'a' of the first ball-end cutting edge 4 satisfies:

[0076]

[0077] Among them, H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0078] H 钛合金 The hardness of titanium alloy casting material 16;

[0079] K a This is a correction factor, with a value ranging from 3.0 to 8.9;

[0080] D is the diameter of the first ball-end cutting edge 4, and its value ranges from 6 to 12 mm.

[0081] Specifically, the depth of cut b of the second ball-end cutting edge 5 satisfies:

[0082]

[0083] Among them, H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0084] H 钛合金 The hardness of titanium alloy casting material 16;

[0085] K b This is a correction factor, with a value ranging from 2.5 to 8.9;

[0086] D is the diameter of the second ball-end cutting edge 5, and its value ranges from 6 to 12 mm.

[0087] Specifically, the depth of cut c of the third ball-end cutting edge 6 satisfies:

[0088]

[0089] Among them, H Ⅲ The material hardness of the third ball-end cutting edge 6;

[0090] H 钛合金 The hardness of titanium alloy casting material 16;

[0091] K c This is a correction factor, with a value ranging from 2.6 to 8.9;

[0092] D is the diameter of the third ball-end cutting edge 6, and its value ranges from 6 to 12 mm.

[0093] Specifically, the depth of cut d of the fourth ball end cutting edge 7 satisfies:

[0094]

[0095] Among them, H Ⅳ The material hardness of the fourth ball-end cutting edge 7;

[0096] H 钛合金 The hardness of titanium alloy casting material 16;

[0097] K d This is a correction factor, with a value ranging from 2.4 to 7.1;

[0098] D is the diameter of the fourth ball-end cutting edge 7, and its value ranges from 6 to 12 mm.

[0099] 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.

[0100] For example, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have the same shape, size, and material as the first ball-end cutting edge 4. Therefore, H Ⅰ =H Ⅱ =H Ⅲ =H Ⅳ =RHC70; where K b =5.95, at this time, b = 1.2mm; where, K c =6.47, at this time, c = 1.1mm; where, K d =4.81, at this time, d = 1.5mm.

[0101] Furthermore, the working rake angles of four ball-end cutting edges are set to cooperate with each other: the working rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7. This overcomes the impact of uneven machining allowance ribs within the inner cavity of the titanium alloy casting chamber 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 casting chamber 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 overall machining efficiency. The working rake angle γ of the third ball-end cutting edge 6 is set between β and α, i.e., α < γ < β, to bear the main impact and protect the fourth ball-end cutting edge 7. The working rake angle δ of the fourth ball-end cutting edge 7 is greater than β, i.e., δ > β, to improve its sharpness and thus improve overall machining efficiency.

[0102] Specifically, the working rake angle α of the first ball end cutting edge 4 satisfies:

[0103]

[0104] Among them, K α This is a correction factor, with a value ranging from 16.9 to 25.9;

[0105] H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0106] H 钛合金 The hardness of titanium alloy casting material 16;

[0107] a represents the depth of cut of the first ball-end cutting edge 4.

[0108] Specifically, the working rake angle β of the second ball end cutting edge 5 satisfies:

[0109]

[0110] Among them, K β This is a correction factor, with a value range of 13.1 to 25.0;

[0111] H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0112] H 钛合金 The hardness of titanium alloy casting material 16;

[0113] b is the depth of cut of the second ball-end cutting edge 5.

[0114] Specifically, the working rake angle γ of the third ball end cutting edge 6 satisfies:

[0115]

[0116] Among them, K γ This is a correction factor, with a value range of 14.2 to 25.3;

[0117] H Ⅲ The material hardness of the third ball-end cutting edge 6;

[0118] H 钛合金 The hardness of titanium alloy casting material 16;

[0119] c represents the depth of cut of the third ball-end cutting edge 6.

[0120] Specifically, the working rake angle δ of the fourth ball end cutting edge 7 satisfies:

[0121]

[0122] Among them, K δ This is a correction factor, with a value range of 12.5 to 19.6;

[0123] H Ⅳ The material hardness of the fourth ball-end cutting edge 7;

[0124] H 钛合金 The hardness of the titanium alloy casting material;

[0125] d is the depth of cut of the fourth ball-end cutting edge 7.

[0126] 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°.

[0127] For example, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have the same shape, size, and material as the first ball-end cutting edge 4. In this case, H Ⅰ =H Ⅱ =H Ⅲ =H Ⅳ =RHC70; where K β The value is 16.48, b = 1.2 mm, and at this point, β = 1°; where K γ The value is 18.08, c = 1.1 mm, and at this point, γ = 0.5°; where K δ The value is 12.59, d = 1.5 mm, and at this time, δ = 5°.

[0128] Among them, the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 are components of a multi-point cutting tool.

[0129] Specifically, the aforementioned multi-point cutting tool includes a tool holder 1 and a first support body 2 and a second support body 3 mounted on the tool holder 1. To facilitate the installation and replacement of the ball end cutting edge, a first auxiliary support body 8 and a second auxiliary support body 9 are respectively installed at the lower ends of the first support body 2 and the second support body 3. The lower ends of the first auxiliary support body 8 and the first support body 2 are respectively provided with a first mounting groove and a second mounting groove, and the lower ends of the second auxiliary support body 9 and the second support body 3 are respectively provided with a third mounting groove and a fourth mounting groove. The aforementioned first ball end cutting edge 4, second ball end cutting edge 5, third ball end cutting edge 6, and fourth ball end cutting edge 7 are respectively installed in the first mounting groove, the second mounting groove, the third mounting groove, and the fourth mounting groove.

[0130] Generally, the rake angle of the ball end cutting edge is a fixed value. After determining the working rake angles of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6, and the fourth ball end cutting edge 7, the working rake angles of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6, and the fourth ball end cutting edge 7 are adjusted by setting the inclination of the bottom surfaces of the first mounting groove, the second mounting groove, the third mounting groove, and the fourth mounting groove. The bottom surfaces are the surfaces that contact the mounting surfaces of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6, and the fourth ball end cutting edge 7. For example, the fixed rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are α1, β1, γ1, and δ1, respectively. The installation rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are α2, β2, γ2, and δ2, respectively. The working rake angle of the first ball-end cutting edge 4 is α = α1 + α2, the working rake angle of the second ball-end cutting edge 5 is β = β1 + β2, the working rake angle of the third ball-end cutting edge 6 is γ = γ1 + γ2, and the working rake angle of the fourth ball-end cutting edge 7 is δ = δ1 + δ2.

[0131] For example, the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have the same shape and dimensions. In this case, the fixed rake angles α1, β1, γ1, and δ1 of the four ball-end cutting edges satisfy: α1 = β1 = γ1 = δ1, specifically 1.5°. Therefore, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 can be calculated according to the formulas α = α1 + α2, β = β1 + β2, γ = γ1 + γ2, and δ = δ1 + δ2. The installation rake angles of the third ball end cutting edge 6 and the fourth ball end cutting edge 7 are as follows: the installation rake angle of the first ball end cutting edge 4 is α2 = α - α1 = -1.5° - 1.5° = -3°; the installation rake angle of the second ball end cutting edge 5 is β2 = β - β1 = 1° - 1.5° = -0.5°; the installation rake angle of the third ball end cutting edge 6 is γ2 = γ - γ1 = 0.5° - 1.5° = -1°; and the installation rake angle of the fourth ball end cutting edge 7 is δ2 = δ - δ1 = 5° - 1.5° = 3.5°.

[0132] Furthermore, after determining the depth of cut and working rake angle of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7, the distances between the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are determined. Specifically, the distance between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is C1 = b; the distance between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 is C2 = c; and the distance between the lower edges of the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 is C3 = d.

[0133] During cutting, the distance difference between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 is adjustable. For example, after determining the distance difference between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6, the relative positions of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 are adjusted by moving the first support body 2 and the second support body 3 up and down.

[0134] 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 13 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 13 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. The multiple grooves 13 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. 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.

[0135] 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 11. To form an internal cavity to accommodate the depth-of-cut adjustment gear 11, rectangular slots 12 are provided on the mating surfaces of the first support 2 and the second support 3. These rectangular slots 12 together form the internal cavity to accommodate the depth-of-cut adjustment gear 11. The bottom surface of the rectangular slot 12 is a toothed surface that meshes with the depth-of-cut adjustment gear 11. The adjustment mechanism also includes a rotating shaft. One end of the rotating shaft is connected to the depth-of-cut adjustment gear 11, and the other end is connected to a drive assembly mounted on the tool holder 1. There can be two rotating shafts, respectively located at both ends of the depth-of-cut adjustment gear 11.

[0136] When the depth of cut needs to be adjusted, the drive assembly is activated, and the depth of cut adjustment gear 11 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 third ball-end cutting edge 6 are flush. If the depth of cut adjustment gear 11 rotates clockwise, the first carrier 2 drives the first ball-end cutting edge 4 and the second ball-end cutting edge 5 to move away from the inner wall of the titanium alloy casting chamber 16, and the second carrier 3 drives the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 to move closer to the inner wall of the titanium alloy casting chamber 16, thereby adjusting the distance difference C2 between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6.

[0137] Among them, when the depth of cut adjustment gear 11 rotates clockwise, the distance P1 that the second ball-end cutting edge 5 moves away from the end face of the inner cavity of the titanium alloy casting chamber 16 satisfies:

[0138] P1 = v1 * t1

[0139] Wherein, v1 is the linear velocity of the side end face when the depth of cut adjustment gear 11 rotates;

[0140] t1 is the rotation time of the depth-of-cut adjustment gear 11.

[0141] The distance P2 that the third ball-end cutting edge 6 moves close to the inner end face of the titanium alloy casting chamber 16 satisfies:

[0142] P2 = P1

[0143] therefore,

[0144] At this time, the rotation time of the depth-of-cut adjusting gear 11 is:

[0145]

[0146] In this way, the positions of the first support 2 and the second support 3 can be precisely adjusted.

[0147] Furthermore, after determining the distance between the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7, 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.

[0148] Specifically, during machining, the titanium alloy casting chamber 16 rotates at a speed of v2 = 29~37 r / min, and the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6 and the fourth ball end cutting edge 7 feed at a speed of 0.1-0.2 mm / r.

[0149] Specifically, during the initial machining of the inner cavity of the titanium alloy casting 16, the first ball-end cutting edge 4 first cuts the inner cavity of the titanium alloy casting 16. Immediately afterwards, the second ball-end cutting edge 5 performs synchronous cutting on the previous machining trajectory formed by the first ball-end cutting edge 4. At this time, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 are in an idle state. During machining, the titanium alloy casting 16 rotates at a speed of v2 = 29–37 r / min for a period of time. Then, the tool is axially advanced. At this time, the multi-point tool feeds axially at a speed of 0.1-0.2 mm / r. During this process, the third ball end cutting edge 6 cuts on the previous machining trajectory formed by the second ball end cutting edge 5. Immediately afterwards, the fourth ball end cutting edge 7 performs synchronous cutting on the previous machining trajectory formed by the third ball end cutting edge 6. At this time, the depth of cut Y = a + b + c + d of the machining trajectory is completed by the machine tool, which greatly improves the machining efficiency.

[0150] In the initial state, the irregular ribs inside the titanium alloy casting chamber 16 have irregular machining allowances. The first ball-end cutting edge 4 bears the impact of the irregular machining allowance ribs with a small working rake angle to protect the other three ball-end cutting edges. The third ball-end cutting edge 6 mainly bears the impact of the uniform machining allowance ribs with a small working rake angle to protect the fourth ball-end cutting edge 7. The second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 have larger working rake angles to improve the sharpness during cutting, thereby improving the overall machining efficiency and service life of the multi-point cutting tool.

[0151] Specifically, when the first ball-end cutting edge 4 moves axially to the inner cavity at the bottom of the titanium alloy casting chamber 16, the depth of cut adjustment mechanism is used to adjust the distance between the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 and the inner cavity of the titanium alloy casting chamber 16, so as to process the inner cavity at the bottom of the titanium alloy casting chamber 16.

[0152] Specifically, the depth-of-cut adjusting gear 11 is rotated counterclockwise for a period of time. At this time, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 continue cutting, with a cutting depth of v1*t3; after a period of time t4 = t2, the cutting depth adjusting gear 11 continues to rotate counterclockwise. The rotation time of the cutting depth adjusting gear 11 is... At this point, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 continue cutting, with a depth of cut of v1*t5. Thus, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are used to machine the inner cavity at the bottom of the titanium alloy casting 16. Finally, the surface machined by the second ball-end cutting edge 5 is flush with the surface machined by the fourth ball-end cutting edge 7. After machining, the multi-point cutting tool is removed from the titanium alloy casting chamber 16 by controlling the tool holder 23 via the Z-axis support plate.

[0153] Furthermore, during cutting, along the cutting direction, a cleaning device is used to cool, lubricate, and remove debris from the gaps between adjacent surfaces of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7.

[0154] Among them, the above cleaning device includes a first channel 14 and a second channel 15 opened on the first carrier 2 for the flow of gas and liquid. The jet nozzle of the first channel 14 and the liquid spray nozzle of the second channel 15 are located in the gap between the adjacent surfaces of the first ball nose cutting edge 4 and the second ball nose cutting edge 5, and are arranged towards the gap between the third ball nose cutting edge 6 and the fourth ball nose cutting edge 7. In this way, the flow rate of the cutting fluid is increased by the ejected gas to improve the cleaning efficiency of the chips. At the same time, the cooling effect on the multi-point cutting tool is improved by accelerating the air flow on the surfaces of the first ball nose cutting edge 4, the second ball nose cutting edge 5, the third ball nose cutting edge 6 and the fourth ball nose cutting edge 7.

[0155] Specifically, along the cutting forward direction, the liquid spray nozzle of the second channel 15 is arranged above the jet nozzle of the first channel 14. Among them, air or nitrogen is used to flow in the first channel 14, and cutting fluid is used to flow in the second channel 15. The diameter of the jet nozzle of the first channel 14 is x1, and the diameter of the liquid spray nozzle of the second channel 15 is x2. Among them, 1 / 3*R1 < x1 = x2 < 1 / 2*R1. Exemplarily, the gap R1 = 3mm. Therefore, 1mm < x1 = x2 < 1.5mm. Among them, the air outlet rate of the jet nozzle of the first channel 14 is 8.0 - 10m / s; the liquid outlet rate of the liquid spray nozzle of the second channel 15 is 0.25 - 0.3m / s. In this way, the cutting fluid is increased towards the gap between the adjacent surfaces of the first ball nose cutting edge 4, the second ball nose cutting edge 5, the third ball nose cutting edge 6 and the fourth ball nose cutting edge 7 by the ejected gas, so as to improve the effects of cooling, lubricating and removing residual metal chips on the cutting edges in the gap.

[0156] In order to implement the above multi-point machining method for the inner cavity of the titanium alloy casting cabin, the present invention also provides a multi-point cutting tool for machining the titanium alloy casting cabin, as Figure 5 shown. The multi-point cutting tool includes a tool holder 1, a first carrier 2 and a second carrier 3 mounted on the tool holder 1, and a first ball nose cutting edge 4 and a second ball nose cutting edge 5 mounted at the lower end of the first carrier 2, and a third ball nose cutting edge 6 and a fourth ball nose cutting edge 7 mounted at the lower end of the second carrier 3;

[0157] As Figures 5-8As shown, along the cutting direction, the first ball-end cutting edge 4 and the third ball-end cutting edge 6 are flush and cut synchronously; the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 are flush and cut synchronously; the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are not flush. That is to say, during the circumferential cutting along the inner cavity of the titanium alloy casting chamber 16, the first ball-end cutting edge 4 and the third ball-end cutting edge 6 advance side by side, and the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 advance side by side; along the axial feed direction, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 advance side by side, and the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 advance side by side, and the depth of cut along the inner cavity of the titanium alloy casting chamber 16 by the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are different.

[0158] Compared with the prior art, along the cutting direction, the machining tool of the present invention consists of four ball-end cutting edges arranged in pairs. The ball-end surfaces of the first ball-end cutting edge 4 and the third ball-end cutting edge 6 are located in the same plane, and the ball-end surfaces of the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 are located in the same plane. Moreover, there is a height difference between the lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7. That is, the distance difference between the lower edges of the four ball-end cutting edges is not equal to 0. The four cutting edges cut simultaneously, forming a tool with multiple tangent points, and performing multi-tangent point misalignment machining. During the cutting process, the tool cuts circumferentially along the inner cavity of the titanium alloy casting chamber 16 and feeds axially along the inner cavity of the titanium alloy casting chamber 16. After cutting one circumferential cycle along the inner cavity of the titanium alloy casting chamber 16, 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, the third ball-end cutting edge 6 cuts on the previous machining trajectory formed by the second ball-end cutting edge 5, and the fourth ball-end cutting edge 7 cuts on the previous machining trajectory formed by the third ball-end cutting edge 6. In this way, the depth of cut of the machine tool running one machining trajectory is the sum of the depths of cut of the four ball-end cutting edges, which improves the efficiency of single cutting. At the same time, the machining cutting amount is shared by the four ball-end cutting edges, reducing the machining amount borne by a single cutting edge. When machining a single part, the wear borne by a single cutting edge is reduced, thus improving the life of the machining tool. The machining tools have a long service life, thus avoiding frequent tool replacements and improving machining efficiency. The machining time for a single titanium alloy casting chamber with 16 internal cavities can be as low as 3.2 hours, which is about 1.7 times higher than existing technologies.

[0159] The lower edges of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are not flush, meaning there is a height difference between their lower edges. All four ball-end cutting edges cut simultaneously, creating a multi-point misaligned tool for multi-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*, the depth of cut of the third ball-end cutting edge 6 is *c*, and the depth of cut of the fourth ball-end cutting edge 7 is *d*. The distance between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is C1 = b > 0, the distance between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 is C2 = c > 0, and the distance between the lower edges of the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 is C3 = d > 0. The depth of cut Y for one machining trajectory is Y = a + b + c + d.

[0160] Specifically, such as Figure 5 As shown, the multi-point cutting tool includes a tool holder 1 and a first support body 2 and a second support body 3 mounted on the tool holder 1. To facilitate the installation and replacement of the ball end cutting edge, a first auxiliary support body 8 and a second auxiliary support body 9 are respectively installed at the lower ends of the first support body 2 and the second support body 3. To further facilitate the installation and replacement of the ball end cutting edge, the lower ends of the first auxiliary support body 8 and the first support body 2 are respectively provided with a first mounting groove and a second mounting groove for installing the first ball end cutting edge 4 and the second ball end cutting edge 5. The lower ends of the second auxiliary support body 9 and the second support body 3 are respectively provided with a third mounting groove and a fourth mounting groove for installing the third ball end cutting edge 6 and the fourth ball end cutting edge 7.

[0161] Specifically, the first auxiliary support 8 and the second auxiliary support 9 are respectively installed at the lower ends of the first support 2 and the second support 3 via mounting screws 10. One side of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are respectively screwed into the first mounting groove, the second mounting groove, the third mounting groove, and the fourth mounting groove. Along the cutting direction, the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have two opposing surfaces. One surface is the mounting surface for installing the first auxiliary support 8, the first support 2, the second auxiliary support 9, and the second support 3. The other end face is a convex ball-end surface that serves 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.

[0162] Specifically, along the axial feed direction, the two side edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are flush, and the two side edges of the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 are flush. The clearance between the first ball-end cutting edge 4 and the third ball-end cutting edge 6 is R1 = 1 / 4D, the clearance between the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7 is R2 = R1; the clearance between the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is R3 = 2 / 3D, and the clearance between the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 is R4 = R3. This smaller clearance helps to prevent larger chips from entering the adjacent area of ​​the two ball-end cutting edges, reducing wear on the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7. Simultaneously, 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.

[0163] 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.

[0164] Specifically, the depth of cut 'a' of the first ball-end cutting edge 4 satisfies:

[0165]

[0166] Among them, H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0167] H 钛合金 The hardness of titanium alloy casting material 16;

[0168] K a This is a correction factor, with a value ranging from 3.0 to 8.9;

[0169] D is the diameter of the first ball-end cutting edge 4, and its value ranges from 6 to 12 mm.

[0170] Specifically, the depth of cut b of the second ball-end cutting edge 5 satisfies:

[0171]

[0172] Among them, H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0173] H 钛合金 The hardness of titanium alloy casting material 16;

[0174] K b This is a correction factor, with a value ranging from 2.5 to 8.9;

[0175] D is the diameter of the second ball-end cutting edge 5, and its value ranges from 6 to 12 mm.

[0176] Specifically, the depth of cut c of the third ball-end cutting edge 6 satisfies:

[0177]

[0178] Among them, H Ⅲ The material hardness of the third ball-end cutting edge 6;

[0179] H 钛合金 The hardness of titanium alloy casting material 16;

[0180] K c This is a correction factor, with a value ranging from 2.6 to 8.9;

[0181] D is the diameter of the third ball-end cutting edge 6, and its value ranges from 6 to 12 mm.

[0182] Specifically, the depth of cut d of the fourth ball end cutting edge 7 satisfies:

[0183]

[0184] Among them, H Ⅳ The material hardness of the fourth ball-end cutting edge 7;

[0185] H 钛合金 The hardness of titanium alloy casting material 16;

[0186] K d This is a correction factor, with a value ranging from 2.4 to 7.1;

[0187] D is the diameter of the fourth ball-end cutting edge 7, and its value ranges from 6 to 12 mm.

[0188] 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.

[0189] For example, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have the same shape, size, and material as the first ball-end cutting edge 4. Therefore, H Ⅰ =H Ⅱ =H Ⅲ =H Ⅳ =RHC70; where K b =5.95, at this time, b = 1.2mm; where, K c =6.47, at this time, c = 1.1mm; where, K d =4.81, at this time, d = 1.5mm.

[0190] Considering that when machining the side wall near the bottom of the titanium alloy casting chamber 16, the above-mentioned multi-point cutting tool cannot achieve the final machining of the side wall near the bottom of the titanium alloy casting chamber 16, the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 of the present invention can move up and down under the drive of the first carrier 2 and the second carrier 3.

[0191] Specifically, such as Figures 9-12 As shown, a rectangular through slot 101 is provided on the tool holder 1. The inner wall of the rectangular through slot 101 is provided with a plurality of 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 are provided with a plurality of grooves 13 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 close contact with each other. The plurality of grooves 13 on the outer surface of the first support body 2 are fitted into the plurality of protrusions 102 on the inner wall of the rectangular through slot 101 in a one-to-one correspondence. The plurality of grooves 13 on the outer surface of the second support body 3 are fitted into the plurality of 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.

[0192] 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.

[0193] Specifically, the adjustment mechanism includes a depth-of-cut adjustment gear 11. In order to form an internal cavity to accommodate the depth-of-cut adjustment gear 11, rectangular grooves 12 are respectively provided on the side of the first support body 2 and the second support body 3 that are in contact with each other. The rectangular grooves 12 of the first support body 2 and the rectangular grooves 12 of the second support body 3 together form an internal cavity to accommodate the depth-of-cut adjustment gear 11.

[0194] 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 12 is a toothed surface, which can mesh with the depth of cut adjustment gear 11.

[0195] 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 11, 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 11.

[0196] 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 11 are slidably connected to the side end faces of the rectangular groove 12.

[0197] When the depth of cut needs to be adjusted, the drive assembly is activated, and the depth of cut adjustment gear 11 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 third ball-end cutting edge 6 are flush. If the depth of cut adjustment gear 11 rotates clockwise, the first carrier 2 drives the first ball-end cutting edge 4 and the second ball-end cutting edge 5 to move away from the inner wall of the titanium alloy casting chamber 16, and the second carrier 3 drives the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 to move closer to the inner wall of the titanium alloy casting chamber 16, thereby adjusting the distance difference C2 between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6.

[0198] Among them, when the depth of cut adjustment gear 11 rotates clockwise, the distance P1 that the second ball-end cutting edge 5 moves away from the end face of the inner cavity of the titanium alloy casting chamber 16 satisfies:

[0199] P1 = v1 * t1

[0200] Wherein, v1 is the linear velocity of the side end face when the depth of cut adjustment gear 11 rotates;

[0201] t1 is the rotation time of the depth-of-cut adjustment gear 11.

[0202] The distance P2 that the third ball-end cutting edge 6 moves close to the inner end face of the titanium alloy casting chamber 16 satisfies:

[0203] P2 = P1

[0204] therefore,

[0205] At this time, the rotation time of the depth-of-cut adjusting gear 11 is:

[0206]

[0207] In this way, the positions of the first support 2 and the second support 3 can be precisely adjusted.

[0208] 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 11 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.

[0209] The dimensional conditions of the rectangular groove 12 satisfy the following:

[0210] The groove depth w3 of rectangular groove 12 is 1 / 2w2;

[0211] The sidewall length of rectangular groove 12 is w4 = 1 / 4w2;

[0212] The width of rectangular groove 12 is w5 = 2πw2.

[0213] Generally, the larger the working rake angle of a cutting edge, the sharper the edge, but the weaker its impact resistance. Existing 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 titanium alloy casting chamber 16, when four ball-end cutting edges are set in pairs, all four edges must bear the main impact, leading to a simultaneous decrease in the lifespan of all machining tools.

[0214] Therefore, the present invention uses the working rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 that cooperate with each other. That is, the working rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 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.

[0215] Specifically, the fixed rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are α1, β1, γ1, and δ1, respectively. The installation rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are α2, β2, γ2, and δ2, respectively. The working rake angle of the first ball-end cutting edge 4 is α = α1 + α2, the working rake angle of the second ball-end cutting edge 5 is β = β1 + γ2, the working rake angle of the third ball-end cutting edge 6 is γ = γ1 + γ2, and the working rake angle of the fourth ball-end cutting edge 7 is δ = δ1 + δ2.

[0216] Among them, 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 casting 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.

[0217] Among them, the working rake angle γ of the third ball end cutting edge 6 is set between β and α, that is, α<γ<β, so as to bear the main impact and protect the fourth ball end cutting edge 7; the working rake angle δ of the fourth ball end cutting edge 7 is greater than β, that is, δ>β, so as to improve its sharpness and thus improve the overall machining efficiency.

[0218] After determining the values ​​of α, β, γ, and δ, the values ​​of α, β, γ, and δ are adjusted by adjusting the inclination of the bottom surfaces of the first, second, third, and fourth mounting slots and the fixed rake angle values ​​of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6, and the fourth ball end cutting edge 7.

[0219] Specifically, the working rake angle α of the first ball end cutting edge 4 satisfies:

[0220]

[0221] Among them, K α This is a correction factor, with a value ranging from 16.9 to 25.9;

[0222] H Ⅰ The material hardness of the first ball-end cutting edge 4;

[0223] H 钛合金 The hardness of titanium alloy casting material 16;

[0224] a represents the depth of cut of the first ball-end cutting edge 4.

[0225] Specifically, the working rake angle β of the second ball end cutting edge 5 satisfies:

[0226]

[0227] Among them, K β This is a correction factor, with a value range of 13.1 to 25.0;

[0228] H Ⅱ The material hardness of the second ball-end cutting edge 5;

[0229] H 钛合金 The hardness of titanium alloy casting material 16;

[0230] b is the depth of cut of the second ball-end cutting edge 5.

[0231] Specifically, the working rake angle γ of the third ball end cutting edge 6 satisfies:

[0232]

[0233] Among them, K γ This is a correction factor, with a value range of 14.2 to 25.3;

[0234] H Ⅲ The material hardness of the third ball-end cutting edge 6;

[0235] H 钛合金 The hardness of titanium alloy casting material 16;

[0236] c represents the depth of cut of the third ball-end cutting edge 6.

[0237] Specifically, the working rake angle δ of the fourth ball end cutting edge 7 satisfies:

[0238]

[0239] Among them, Kδ This is a correction factor, with a value range of 12.5 to 19.6;

[0240] H Ⅳ The material hardness of the fourth ball-end cutting edge 7;

[0241] H 钛合金 The hardness of the titanium alloy casting material;

[0242] d is the depth of cut of the fourth ball-end cutting edge 7.

[0243] 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°.

[0244] For example, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have the same shape, size, and material as the first ball-end cutting edge 4. In this case, H Ⅰ =H Ⅱ =H Ⅲ =H Ⅳ =RHC70; where K β The value is 16.48, b = 1.2 mm, and at this point, β = 1°; where K γ The value is 18.08, c = 1.1 mm, and at this point, γ = 0.5°; where K δ The value is 12.59, d = 1.5 mm, and at this time, δ = 5°.

[0245] Specifically, the fixed rake angle values ​​of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 are determined by the shape of the ball-end cutting edge itself. For example, if the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 have the same shape, then the fixed rake angle values ​​α1, β1, γ1, and δ1 of the four ball-end cutting edges satisfy: α1 = β1 = γ1 = δ1, specifically 1.5°. Therefore, according to the formulas α = α1 + α2, β = β1 + β2, γ = γ1 + γ2, δ = ... δ1+δ2 can be used to calculate the installation rake angles of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6, and the fourth ball end cutting edge 7. Specifically, the installation rake angle of the first ball end cutting edge 4 is α2=α-α1=-1.5°-1.5°=-3°, the installation rake angle of the second ball end cutting edge 5 is β2=β-β1=1°-1.5°=-0.5°, the installation rake angle of the third ball end cutting edge 6 is γ2=γ-γ1=0.5°-1.5°=-1°, and the installation rake angle of the fourth ball end cutting edge 7 is δ2=δ-δ1=5°-1.5°=3.5°.

[0246] After determining the mounting rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7, the inclination of the bottom surface within the first, second, third, and fourth mounting slots is set. The bottom surface is the surface that contacts the mounting surface of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, or the fourth ball-end cutting edge 7. The inclination of this bottom surface is the same as the mounting rake angle of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7, thereby adjusting the mounting rake angles of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7.

[0247] Specifically, such as Figure 9 As shown, the first carrier 2 consists of upper and lower parts. The upper part is installed in a rectangular through slot 101 within the tool holder 1, and the lower part is screwed to the lower end of the upper part for easy replacement. A first auxiliary carrier 8 is installed on the lower part of the first carrier 2 via a mounting screw 10. The lower parts of both the first auxiliary carrier 2 and the first carrier 2 have a first mounting slot and a second mounting slot respectively for installing the first ball-end cutting edge 4 and the second ball-end cutting edge 5. Figure 4 As shown, the bottom surface inclination of the first mounting groove is α2. This inclination is machined during the machining of the lower part of the first auxiliary support 8 to adjust the working rake angle of the first ball-end cutting edge 4. The second mounting groove has the same structure as the first mounting groove, except that the bottom surface inclination of the second mounting groove is β2.

[0248] Specifically, the second auxiliary support body 9 and the second support body 3 have the same structure as the first auxiliary support body 8 and the second support body 3, respectively. The difference lies in the bottom inclination of the third mounting groove and the fourth mounting groove respectively opened at the lower end of the second auxiliary support body 9 and the second support body 3. The bottom inclination of the third mounting groove is γ2 and the bottom inclination of the fourth mounting groove is δ2.

[0249] Considering the small gaps between the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7 (for example, R2 = R1 = 3mm, R3 = R4 = 8mm), during the cutting process, the existing cutting fluid supply method may not be able to reach the gaps. Therefore, the end faces at the gaps between these cutting edges cannot be cooled. Furthermore, chips may enter and accumulate in these gaps, potentially causing wear and tear on the cutting edges, reducing their service life.

[0250] To solve the above problems, a cleaning device can be provided to cool, lubricate and remove residual metal chips at the gaps between the adjacent surfaces of the first ball-nose cutting edge 4, the second ball-nose cutting edge 5, the third ball-nose cutting edge 6 and the fourth ball-nose cutting edge 7 during cutting.

[0251] Specifically, the above cleaning device includes a first channel 14 and a second channel 15 opened on the first carrier 2 for the flow of gas and liquid. The air jet outlet of the first channel 14 and the liquid jet outlet of the second channel 15 are located in the gap between the adjacent surfaces of the first ball-nose cutting edge 4 and the second ball-nose cutting edge 5, and are arranged towards the gap between the third ball-nose cutting edge 6 and the fourth ball-nose cutting edge 7.

[0252] In order to increase the flow rate of the cutting fluid ejected from the second channel 15 to clean the chips adhered to the adjacent edge gaps of the first ball-nose cutting edge 4, the second ball-nose cutting edge 5, the third ball-nose cutting edge 6 and the fourth ball-nose cutting edge 7, the present invention uses the ejected gas to increase the flow rate of the cutting fluid, so as to improve the cleaning efficiency of the chips. At the same time, by accelerating the air flow on the surfaces of the first ball-nose cutting edge 4, the second ball-nose cutting edge 5, the third ball-nose cutting edge 6 and the fourth ball-nose cutting edge 7, the cooling effect on the multi-point cutting tool is improved.

[0253] Specifically, along the cutting forward direction, the liquid jet outlet of the second channel 15 is arranged above the air jet outlet of the first channel 14. Among them, air or nitrogen is used for flowing in the first channel 14, and cutting fluid is used for flowing in the second channel 15. The diameter of the air jet outlet of the first channel 14 is x1, and the diameter of the liquid jet outlet of the second channel 15 is x2, where 1 / 3*R1 < x1 = x2 < 1 / 2*R1. Exemplarily, the gap R1 = 3mm, so 1mm < x1 = x2 < 1.5mm. Among them, the air outlet rate of the air jet outlet of the first channel 14 is 8.0 - 10m / s; the liquid outlet rate of the liquid jet outlet of the second channel 15 is 0.25 - 0.3m / s. In this way, the ejected gas increases the cutting fluid towards the gap between the adjacent surfaces of the first ball-nose cutting edge 4, the second ball-nose cutting edge 5, the third ball-nose cutting edge 6 and the fourth ball-nose cutting edge 7, so as to improve the effects of cooling, lubricating and removing residual metal chips on the cutting edges in the gap.

[0254] In order to enable the first channel 14 to stably eject gas and enable the second channel 15 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 14 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 14. The liquid inlet of the second channel 15 is connected to the liquid supply device, and the liquid supply device includes a liquid delivery pipe for delivering cutting fluid into the second channel 15.

[0255] Furthermore, to better realize the above-mentioned multi-point machining method for titanium alloy casting chambers, the present invention also provides a multi-point machining apparatus. This multi-point machining apparatus includes the aforementioned multi-point cutting tool and a drive device for controlling the movement state of the multi-point cutting tool. The drive device includes a tool holder 23 fixedly connected to the tool holder 1 and a machine tool assembly for driving the tool holder 23 to move, thereby enabling the multi-point cutting tool to move axially within the inner cavity of the titanium alloy casting chamber 16 and adjusting the distance between the multi-point cutting tool and the inner cavity of the titanium alloy casting chamber 16.

[0256] Specifically, such as Figure 13 As shown, the above-mentioned processing device includes a multi-point cutting tool and a tool bar 23 with one end fixedly connected to the tool holder 1. The other end of the tool bar 23 is fixedly disposed in the base 24, which is mounted on the Z-axis support plate of the machine tool. Thus, the base 24 is controlled by the Z-axis support plate of the machine tool to drive the tool bar 23 to move, thereby driving the multi-point cutting tool to move in the direction of the Z-axis support plate to perform cutting operations.

[0257] Specifically, the parameters of tool holder 23 satisfy:

[0258] Diameter E = 0.35 * E1;

[0259] Length L = L1 + 5;

[0260] Strength coefficient

[0261] Among them, E1 is the inner diameter of the titanium alloy casting chamber 16;

[0262] L1 represents the depth of the 16-cavity titanium alloy casting chamber.

[0263] For example, E1 = 760mm, L1 = 920mm, therefore, It can be seen that t≤5, which belongs to a high-strength system, and the strength of tool holder 23 can meet the cutting requirements.

[0264] 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 16, which are used to clamp the titanium alloy casting chamber 16 axially to ensure the stability of the titanium alloy casting chamber 16 during cutting, thereby improving the cutting efficiency.

[0265] Specifically, the clamping fixture includes an upper ring 25 and a lower ring 26 fixedly connected to the upper ring 25 via a screw 27. The upper ring 25 is fixed to the end face of the machine tool chuck and is used to hold the titanium alloy casting chamber 16. The lower ring 26 is fixedly connected to the upper ring 25 via the screw 27 and clamps the titanium alloy casting chamber 16 between the upper ring 25 and the lower ring 26, axially pressing the titanium alloy casting chamber 26. Thus, this clamping fixture concentrates the clamping force in the axial direction, reducing the radial force on the titanium alloy casting chamber 16, greatly reducing clamping deformation of the titanium alloy casting chamber 16, and improving stable cutting control of the titanium alloy casting chamber 16.

[0266] To further improve the stability of clamping the titanium alloy casting 16, the upper ring 25 and the lower ring 26 are provided with a stop with a clearance of 0.1mm from the outer shape of the titanium alloy casting 16, so as to restrict the five degrees of freedom of the titanium alloy casting 16 in the X, Y, Z, A and B directions.

[0267] Specifically, to facilitate the clamping of the titanium alloy casting housing 16, the parameters of the upper ring 25 meet the following requirements:

[0268] Inner diameter j1=0.9E1;

[0269] Outer diameter j2 = 1.2E1.

[0270] The parameters of the lower ring 26 satisfy:

[0271] Inner diameter j3=0.97E1;

[0272] Outer diameter j4 = 1.2E1.

[0273] The parameters of screw 27 satisfy:

[0274] Length g = 1.1L1.

[0275] Specifically, four screws 27 are provided, evenly distributed between the upper ring 25 and the lower ring 26. Each end of the screw 27 has a matching nut, which secures the upper ring 25 and the lower ring 26 by engaging the screws 27 with the nuts. For example, the nut is a GBT6170 nut M20, and a torque wrench is used to tighten it.

[0276] 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:

[0277]

[0278] Among them, T 扭矩 =M = 45 ± 3 N·m;

[0279] K 扭矩The torque coefficient corresponding to this nut is 0.15;

[0280] d 螺杆 The diameter of the end where the screw 27 mates with the nut is 0.020 μm.

[0281] at this time, The total clamping force f of the four nuts on the lower ring 26 总 =4f1=60~64KN.

[0282] 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 16 remains in a stable clamping state during the machining process.

[0283] For example, the external dimensions of the titanium alloy casting chamber 16 were measured by laser scanner or dial indicator. Before clamping, the inner diameter depth of the titanium alloy casting chamber 16 was L1 = 1m; after clamping, the inner diameter depth of the titanium alloy casting chamber 16 was 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 16, which meets the processing requirements.

[0284] To further improve the service life of multi-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 faces of the first ball cutting edge 4 and the third ball cutting edge 6, and to cool, lubricate, and remove debris from the two end faces of the first ball cutting edge 4, the second ball cutting edge 5, the third ball cutting edge 6, and the fourth ball cutting edge 7.

[0285] Specifically, along the direction of the rake angle, 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 third ball-end cutting edge 6. 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 third ball-end cutting edge 6, then flows downwards through the side ends of the first ball-end cutting edge 4 and the third ball-end cutting edge 6 to the side end faces of the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7; additionally, a small portion of the cutting fluid flows into the gap between the adjacent surfaces of the first ball-end cutting edge 4 and the third ball-end cutting edge 6, and the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7.

[0286] 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.

[0287] During operation, the clamping fixture drives the titanium alloy casting chamber 16 to rotate at a speed of 29-37 r / min; the machine tool Z-axis support plate controls the base 24 to move the tool holder 23, which in turn drives the multi-point cutting tool to move in the direction of the Z-axis support plate, so that the multi-point cutting tool can feed axially 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 faces of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6 and the fourth ball end cutting edge 7, so as to cooperate with the cleaning device to achieve efficient cooling, lubrication and chip removal of the first ball end cutting edge 4, the second ball end cutting edge 5, the third ball end cutting edge 6 and the fourth ball end cutting edge 7 in all directions.

[0288] Compared with the prior art, the multi-point machining method of the present invention uses two pairs of four ball-end cutting edges, which are arranged parallel to each other but 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 four ball-end cutting edges, which improves the machining efficiency. During cutting, the four ball-end cutting edges with different working rake angles reduce the impact of the uneven machining allowance ribs in the inner cavity of the titanium alloy casting on the tool life. Specifically, one ball-end cutting edge with a smaller working rake angle is used to bear the main impact to protect the other three ball-end cutting edges, and two ball-end cutting edges with larger working rake angles are used to ensure the overall sharpness of the tool. In this way, the tool life is improved and the machining efficiency is increased.

[0289] The machining tool of this invention is a multi-point staggered tool composed of four ball-end cutting edges, that is, the four ball-end cutting edges cut simultaneously, and the distance difference between the lower edges of the four ball-end cutting edges is not equal to 0. In this way, the depth of cut of the machine tool running one machining trajectory is the sum of the depths of cut of the four ball-end cutting edges, which improves the efficiency of single cutting. In addition, by setting the working rake angle combination of the four ball-end cutting edges, that is, α<γ<β<δ, the overall sharpness of the machining tool is improved while ensuring the overall impact resistance of the tool, thereby improving the machining efficiency.

[0290] 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, 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 16 during the machining process. In this way, the inner cavity at the bottom of the titanium alloy casting chamber 16 can be cut, so as to achieve all-round machining of the inner cavity of the titanium alloy casting chamber 16 without dead angles, thereby improving the machining efficiency.

[0291] The machining tools of this invention have a long service life, thus avoiding frequent tool replacements and improving machining efficiency. The machining time for a single titanium alloy casting chamber 16 inner cavity can be as low as 3.2 hours, which is about 1.7 times higher than the prior art.

[0292] When machining the inner cavity of the titanium alloy casting chamber 16, this invention uses four ball-end cutting edges to distribute 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 three ball-end cutting edges. That is, in the initial state, the machining allowance of the ribs in the inner cavity of the titanium alloy casting chamber 16 is uneven. One ball-end cutting edge contacts the ribs first. The ball-end cutting edge with a smaller working rake angle has good 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 three ball-end cutting edges, thus improving the service life of the machining tool.

[0293] When machining the inner cavity of the titanium alloy casting chamber 16, the first ball-end cutting edge 4 bears the main impact with a small working rake angle. Along the cutting direction, the second ball-end cutting edge 5, whose cutting point is located directly behind the first ball-end cutting edge 4, bears a smaller impact. Since the two are close together, they can be considered as continuous cutting, further reducing the impact on the second ball-end cutting edge 5. Because the first ball-end cutting edge 4 bears the impact of the uneven ribs, the third ball-end cutting edge 6 avoids the phenomenon of local discontinuous cutting on the uneven end face. Along the cutting direction, the fourth ball-end cutting edge 7, whose cutting point is located directly behind the third ball-end cutting edge 6, bears a smaller impact. Since the fourth ball-end cutting edge 7 is close to the third ball-end cutting edge 6, it can be considered as continuous cutting, further reducing the impact on the fourth ball-end cutting edge 7. This further improves the service life of the machining tool.

[0294] 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 machining tool. The service life of a single cutting edge is as low as 8.7 hours, which is 17.4-26.1 times higher than the existing technology.

[0295] All four 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 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.

[0296] Example 1:

[0297] A method for machining the inner cavity of a titanium alloy casting includes the following steps:

[0298] S101: Using clamping fixtures, the titanium alloy casting chamber 16 is pressed axially.

[0299] Specifically, the upper ring 25 is fixed to the end face of the machine tool chuck, and one end of the titanium alloy casting chamber 16 is placed inside the stop of the upper ring 25; then the stop of the lower ring 26 is clamped on the other end face of the titanium alloy casting chamber 16, and the lower ring 26 is fixedly connected to the upper ring 25 by the cooperation of the screw 27 and the nut, so as to restrict the five degrees of freedom of the titanium alloy casting chamber 16 in the X, Y, Z, A and B directions.

[0300] Among them, the inner diameter of the upper ring 25 is j1 = 0.9E1 = 684 mm, and the outer diameter of the upper ring 25 is j2 = 1.2E1 = 912 mm; the inner diameter of the lower ring 26 is j3 = 0.97E1 = 737.2 mm, and the outer diameter of the lower ring 26 is j4 = 1.2E1 = 912 mm; the length of the screw 27 is g = 1.1L1 = 1012 mm.

[0301] Step 2: Connect the multi-point cutting tool to the device used to control axial feed or axial discharge;

[0302] Specifically, the tool holder 1 of the multi-point cutting tool is fixedly connected to the tool shank 23, and the other end of the tool shank 23 is fixedly set in the base 24. The base 24 is mounted on the Z-axis support plate of the machine tool. Thus, the base 24 is controlled by the Z-axis support plate of the machine tool to drive the tool shank 23 to move, thereby driving the multi-point cutting tool to move in the direction of the Z-axis support plate to perform cutting operations.

[0303] The diameter of the tool holder 23 is E = 0.35 * E1 = 0.35 × 760 = 266 mm; the length of the tool holder 23 is L = L1 + 5 = 920 + 5 = 925 mm.

[0304] S103: Set the tool feed position and adjust the tool status;

[0305] 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 port of the titanium alloy casting chamber 16 as the zero point, and the surface parallel to the inner cavity port of the top of the titanium alloy casting chamber 16 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 16, that is, at -135°.

[0306] Specifically, the machine tool is adjusted so that the first support body 2 and the second support body 3 are perpendicular to the end face of the feed position; the depth of cut adjustment gear 11 is rotated clockwise for a certain period of time. The distance between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 is c.

[0307] Step 4: Adjust the state of the titanium alloy casting chamber 16 and move the multi-point cutting tool to the tool feeding position;

[0308] 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 16 to rotate counterclockwise; and the Z-axis support plate controls the movement of the tool holder 23 to move the multi-point cutting tool to the tool feeding position.

[0309] Step 5: Use the multi-point cutting tool to machine the inner cavity of the titanium alloy casting chamber 16;

[0310] Specifically, during machining, the multi-point cutting tool feeds at a speed of 0.1 mm / r; the titanium alloy casting chamber 16 rotates at a speed of v2 = 34 r / min.

[0311] Specifically, during the initial machining of the inner cavity of the titanium alloy casting chamber 16, the first ball-end cutting edge 4 first cuts the inner cavity of the titanium alloy casting chamber 16. Immediately afterwards, the second ball-end cutting edge 5 performs synchronous cutting on the previous machining trajectory formed by the first ball-end cutting edge 4. At this time, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 are in an idle state. For a period of time... Then, the axial feed begins. During this process, the third ball-end cutting edge 6 cuts on the previous machining trajectory formed by the second ball-end cutting edge 5. Immediately afterwards, the fourth ball-end cutting edge 7 performs synchronous cutting on the previous machining trajectory formed by the third ball-end cutting edge 6. At this time, the depth of cut Y = a + b + c + d of one machining trajectory is achieved by the machine tool, which greatly improves the machining efficiency.

[0312] Specifically, when the first ball-end cutting edge 4 moves axially to the inner cavity at the bottom of the titanium alloy casting chamber 16, the depth of cut adjustment mechanism is used to adjust the distance between the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 and the inner cavity of the titanium alloy casting chamber 16, so as to process the inner cavity at the bottom of the titanium alloy casting chamber 16.

[0313] Specifically, the depth-of-cut adjusting gear 11 is rotated counterclockwise for a period of time. At this time, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 continue cutting, with a cutting depth of v1*t3; after a period of time t4 = t2, the cutting depth adjusting gear 11 continues to rotate counterclockwise. The rotation time of the cutting depth adjusting gear 11 is... At this point, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 continue cutting, with a depth of cut of v1*t5. Thus, the first ball-end cutting edge 4 and the second ball-end cutting edge 5 are used to machine the inner cavity at the bottom of the titanium alloy casting 16. Finally, the surface machined by the second ball-end cutting edge 5 is flush with the surface machined by the fourth ball-end cutting edge 7. After machining, the multi-point cutting tool is removed from the titanium alloy casting chamber 16 by controlling the tool holder 23 via the Z-axis support plate.

[0314] If a machining depth of cut is less than the machining allowance, the position of the tool holder 23 is adjusted on the machine tool to adjust the depth of cut of the second ball-end cutting edge 5, so that the remaining machining allowance is cut through the second ball-end cutting edge 5; the Z-axis support plate controls the tool holder 23 to control the axial movement of the multi-point tool for reciprocating cutting. If a machining depth of cut is greater than the machining allowance, the depth of cut of the third ball-end cutting edge 6 is finely adjusted through the depth of cut adjustment gear 11 to achieve machining of the titanium alloy casting 16.

[0315] Among them, the depth of cut of the first ball-end cutting edge 4 1mm, its working rake angle -1.5°, its mounting front angle α2=α-α1=-1.5°-1.5°=-3°;

[0316] Among them, the depth of cut of the second ball-end cutting edge 5 1.2mm, its working rake angle Its mounting angle β2 = β - β1 = 1° - 1.5° = -0.5°;

[0317] Among them, the depth of cut of the third ball-end cutting edge 6 Its working front angle Its mounting angle γ2 = γ - γ1 = 0.5° - 1.5° = -1°;

[0318] Among them, the depth of cut of the fourth ball-end cutting edge 7 Its working front angle 5°, its installation front angle δ2=δ-δ1=5°-1.5°=3.5°.

[0319] The depth of cut for one machining trajectory of the machine tool is Y = a + b + c + d = 4.8 mm.

[0320] During axial feed, the distance between the lower edges of the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is C1 = 1.2 mm; the distance between the lower edges of the second ball-end cutting edge 5 and the third ball-end cutting edge 6 is C2 = 1.1 mm; and the distance between the lower edges of the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 is C3 = 1.5 mm.

[0321] The gap between the first ball-end cutting edge 4 and the third ball-end cutting edge 6 is R1 = R2 = 1 / 4D = 3mm, where R2 is the gap between the second ball-end cutting edge 5 and the fourth ball-end cutting edge 7.

[0322] Wherein, the gap between the first ball-end cutting edge 4 and the second ball-end cutting edge 5 is R3 = R4 = 2 / 3D = 8mm, and R4 is the gap between the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7.

[0323] Wherein, w1=w2=20mm, the groove depth of rectangular groove 12 is w3=1 / 2w2=10mm; the side wall length of rectangular groove 12 is w4=1 / 4w2=5mm; the width of rectangular groove 12 is w5=2πw2=126mm; in the initial state, the bottoms of the first ball end cutting edge 4 and the third ball end cutting edge 6 are flush.

[0324] Among them, one end face of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6 and the fourth ball-end cutting edge 7 is a mounting surface, which is screwed into the first mounting groove, the second mounting groove, the third mounting groove and the fourth 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, the second mounting groove, the third mounting groove or the fourth mounting groove through the mounting surface.

[0325] Step 6: During cutting, cool, lubricate and remove chips from the multi-point cutting tool along the cutting direction.

[0326] Specifically, during cutting, cutting fluid is sprayed onto the ball faces of the first ball-end cutting edge 4 and the third ball-end cutting edge 6 using a cutting fluid supply device to cool, lubricate, and remove larger chips from the outside of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7. At the same time, the air supply device and the liquid supply device are activated to cool, lubricate, and remove fine debris from the gaps between adjacent surfaces of the first ball-end cutting edge 4, the second ball-end cutting edge 5, the third ball-end cutting edge 6, and the fourth ball-end cutting edge 7.

[0327] Specifically, the outlet diameter X3 = 5 / 4D = 15mm, and the cutting fluid flow rate at the outlet is 0.3m / s.

[0328] Specifically, x1 = x2 = 1.4 mm; where the air velocity of the jet nozzle of the first channel 14 is 10 m / s; and the liquid velocity of the liquid nozzle of the second channel 15 is 0.3 m / s.

[0329] Using this method, the processing time for a single piece is 3.2 hours. The service life of the first ball end cutting edge 4 is 8.7 hours, the service life of the second ball end cutting edge 5 is 14.5 hours, the service life of the third ball end cutting edge 6 is 9.1 hours, and the service life of the fourth ball end cutting edge 7 is 16 hours.

[0330] Comparative Example 1:

[0331] A method for machining the inner cavity of a titanium alloy casting chamber, which differs from Example 1 in that...

[0332] 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°.

[0333] 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.

[0334] Compared with Comparative Example 1, the present invention significantly improves processing efficiency, tool life, and reduces manual intervention. See below for details.

[0335] Table 1. Processing effects of Examples 1-6 and Comparative Example 1

[0336]

[0337]

[0338] As shown in Table 1, the processing time for a single part in this invention is 3.2 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 multi-point cutting tool of this invention can significantly improve processing efficiency.

[0339] During the processing, the continuous processing time of the cutting edge of the present invention is not less than 8.7 hours and can reach up to 16 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 multi-cutting point cutting tool of the present invention can significantly improve the service life of the cutting tool. There is no need to replace the cutting tool during the processing, which improves the processing efficiency and reduces the human intervention rate.

[0340] Therefore, the present invention utilizes the above-mentioned multi-point cutting tool to perform intermittent and efficient turning of the inner cavity of the titanium alloy casting chamber, which can effectively solve the problem of frequent impact of the part on the tool, resulting in rapid tool chipping or wear, and can effectively improve the cutting efficiency.

[0341] 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 multi-point, characterized in that: The method comprises synchronously cutting the titanium alloy cabin inner cavity by using a first ball head cutting edge, a second ball head cutting edge, a third ball head cutting edge and a fourth ball head cutting edge. In the cutting process, the lower edges of the first ball head cutting edge, the second ball head cutting edge, the third ball head cutting edge and the fourth ball head cutting edge are not flush; and along the cutting direction, the first ball head cutting edge and the third ball head cutting edge are flush, and the second ball head cutting edge and the fourth ball head cutting edge are flush. The lower end of the first bearing body is provided with a first mounting groove and a second mounting groove for mounting the first ball head cutting edge and the second ball head cutting edge, respectively. 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 lower end of the second bearing body is provided with a third mounting groove and a fourth mounting groove for mounting the third ball head cutting edge and the fourth ball head cutting edge, respectively. The inclination of the bottom surface of the third mounting groove and the fixed value of the rake angle of the third ball head cutting edge are equal to the working rake angle of the third ball head cutting edge. The inclination of the bottom surface of the fourth mounting groove and the fixed value of the rake angle of the fourth ball head cutting edge are equal to the working rake angle of the fourth ball head cutting edge. The working rake angle α of the first ball head cutting edge, the working rake angle β of the second ball head cutting edge, the working rake angle γ of the third ball head cutting edge and the working rake angle δ of the fourth ball head cutting edge satisfy: α < γ < β < δ. In the cutting process, the cutting tool cuts along the circumference of the titanium alloy cabin inner cavity, and the tool advances axially along the titanium alloy cabin inner cavity. After cutting along the circumference of the titanium alloy cabin inner cavity 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, the third ball head cutting edge cuts on the previous machining track formed by the second ball head cutting edge, and the fourth ball head cutting edge cuts on the previous machining track formed by the third ball head cutting edge.

2. The multi-point machining method according to claim 1, characterized in that: In the cutting process, the distance between the lower edges of the first ball head cutting edge and the second ball head cutting edge is equal to the cutting depth of the second ball head cutting edge. 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 H is the material hardness of the second ball head cutting edge; H 钛合金 H is the hardness of the titanium alloy casting cabin material; K b K is a correction coefficient, the value range is 2.5-8.9; D is the diameter of the second ball head cutting edge, the value range is 6-12 mm.

3. The multi-point machining method according to claim 2, wherein: In the cutting process, the distance between the lower edges of the third ball head cutting edge and the fourth ball head cutting edge is equal to the cutting depth of the fourth ball head cutting edge. The cutting depth c of the third ball head cutting edge satisfies: wherein H Ⅲ is the material hardness of the third ballnose cutting edge; H 钛合金 is the hardness of the titanium alloy cast cabin material; K c is a correction coefficient, with a value range of 2.6-8.9; and D is the diameter of the third ballnose cutting edge, with a value range of 6-12 mm. The cutting depth d of the fourth ball head cutting edge satisfies: wherein H Ⅳ is the material hardness of the fourth ballnose cutting edge; H 钛合金 is the hardness of the titanium alloy tank material; K d is a correction coefficient, with a value range of 2.4-7.1; and D is the diameter of the fourth ballnose cutting edge, with a value range of 6-12 mm. When the tool advances axially, the distance between the lower edges of the second ball head cutting edge and the third ball head cutting edge is equal to the cutting depth of the third ball head cutting edge.

4. The multi-point machining method of claim 3, wherein: The total cutting depth of the first ball head cutting edge, the second ball head cutting edge, the third ball head cutting edge and the fourth ball head cutting edge in one track is the sum of the cutting depths of the four ball head cutting edges.

5. The multi-point machining method of claim 1, wherein: In the cutting process, the working rake angle of the first ball head cutting edge is smaller than the working rake angle of the second ball head cutting edge. 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; a is the cutting depth of the first ball nose cutting edge; 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 13.1-25.0; and b is the cutting depth of the second ballnose cutting edge.

6. The multi-point machining method of claim 5, wherein: The working rake angle γ of the third ball head cutting edge satisfies: wherein H Ⅲ is the material hardness of the third ballnose cutting edge; H 钛合金 is the hardness of the titanium alloy cast cabin material; K γ is a correction coefficient, with a value range of 14.2-25.3; and c is the cutting depth of the third ballnose cutting edge. The working rake angle δ of the fourth ball head cutting edge satisfies: wherein H Ⅳ is the material hardness of the fourth ballnose cutting edge; H 钛合金 is the hardness of the titanium alloy cast cabin material; K δ is a correction coefficient, with a value range of 12.5-19.6; and d is the cutting depth of the fourth ballnose cutting edge.

7. The multi-point machining method of claim 1, wherein: The first ball head cutting edge, the second ball head cutting edge, the third ball head cutting edge and the fourth ball head cutting edge perform circumferential cutting along the axial feed of the inner cavity of the titanium alloy casting cabin. During cutting, the cutting direction at any time is perpendicular to the axial feed direction of the first ball head cutting edge, the second ball head cutting edge, the third ball head cutting edge or the fourth ball head cutting edge.

8. The multi-point machining method of claim 1, wherein: During cutting, the gap between the adjacent surfaces of the first ball head cutting edge, the second ball head cutting edge, the third ball head cutting edge and the fourth ball head cutting edge is cooled, lubricated and cleaned by using the cleaning device in the direction of cutting advancement.

9. The multi-point machining method of claim 1, wherein: During cutting, when the first ball head cutting edge is processed 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 process the inner cavity of the bottom of the titanium alloy casting cabin.

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