Blade root milling cutter and its preparation method

Abstract

The present invention relates to a blade root milling cutter and a preparation method thereof. The blade root milling cutter includes a central cylinder and a formed cutting edge arranged on the outer wall of the central cylinder. Each formed cutting edge includes a plurality of cutting edge segments, and the plurality of cutting edge segments are evenly distributed in a circumferential shape around the central cylinder and are sequentially arranged along the axial direction of the central cylinder. Among two adjacent cutting edge segments, the opposite end faces of the two cutting edge segments are located in the same plane, and the plane is perpendicular to the central cylinder. In the present invention, the originally integral formed cutting edge is divided into a plurality of cutting edge segments, and different cutting edge segments are located at different positions of the central cylinder. When one of the cutting edge segments contacts the blade root and mills the root, the remaining cutting edge segments do not contact the root. Therefore, the contact length between the formed cutting edge and the root is reduced, the cutting amount of each cutting edge segment is reduced, thereby the cutting resistance can be reduced, the milling cutter can be prevented from bending and vibrating greatly, which is beneficial to improving the machining accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of milling cutters, and particularly relates to a blade root milling cutter and a preparation method thereof. Background Art

[0002] Blades are important parts of equipment such as steam turbines and aero-engines. When preparing blades, milling is usually used. The blade root is used to install the blade on a steam turbine or an aero-engine. A common blade root structure is a fir-tree blade root. When machining a fir-tree blade root, a special forming milling cutter is generally used for rough milling and finish milling. The fir-tree blade root can be machined to the designed size through two milling processes. For details, reference can be made to the invention patent with the application number CN201210538134.X - a rough milling method for a fir-tree blade root. Existing blade root milling cutters include a central column body, and a plurality of forming cutting edges evenly distributed around the central column body are arranged on the surface of the central column body. The outer shape of the forming cutting edge is adapted to the shape of the blade root. For details, reference can be made to the utility model patent with the application number CN200920306966.2 - a longitudinal tree-type blade root milling cutter with a TiN coating.

[0003] When the existing blade root milling cutter is used for milling, as Figure 1 and Figure 2 shown, the milling cutter feeds from the left side to the right side in Figure 2 , and the milling cutter rotates at a high speed, so that each forming cutting edge cuts the side surface of the blade root. Since the forming surface of the blade root has a certain height, the contact length a between the forming cutting edge and the forming surface of the blade root is relatively large. Therefore, the cutting resistance is large, which easily causes the milling cutter to bend and vibrate. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a blade root milling cutter, which can reduce the cutting resistance, prevent the milling cutter from bending, and reduce the vibration of the milling cutter. A preparation method is also provided for preparing the blade root milling cutter.

[0005] To solve the above problems, the technical solution adopted by the present invention is: a blade root milling cutter, including a central column body and forming cutting edges arranged on the outer wall of the central column body,

[0006] each of the forming cutting edges includes a plurality of cutting edge segments, the plurality of cutting edge segments are evenly distributed around the central column body in a circumferential shape, and the plurality of cutting edge segments are sequentially arranged along the axial direction of the central column body;

[0007] Among two adjacent cutting edge segments, the end faces of the two cutting edge segments facing each other are located in the same plane, and the plane is perpendicular to the central column body.

[0008] Further, the cutting edge segment includes a first cutting edge segment, a second cutting edge segment, and a third cutting edge segment.

[0009] Further, there are two first blade segments, two second blade segments, and two third blade segments. The two first blade segments are centrosymmetric with respect to the central axis of the central cylinder, the two second blade segments are centrosymmetric with respect to the central axis of the central cylinder, and the two third blade segments are centrosymmetric with respect to the central axis of the central cylinder.

[0010] Further, the two first blade segments are integrally connected by a first connecting column, the two second blade segments are integrally connected by a second connecting column, and the two third blade segments are integrally connected by a third connecting column;

[0011] The central cylinder is provided with a first positioning groove, a second positioning groove, and a third positioning groove that radially penetrate the central cylinder. The first connecting column, the second connecting column, and the third connecting column are respectively located in the first positioning groove, the second positioning groove, and the third positioning groove, and the first connecting column, the second connecting column, and the third connecting column are connected to the central cylinder through connecting members.

[0012] Further, the first blade segment, the second blade segment, and the third blade segment are arranged in sequence from the milling end to the clamping end. The connecting member includes a connecting screw and a positioning pin. The first connecting column is connected to the central cylinder by two screws. A threaded hole is provided in the center of the first connecting column. A pin hole is provided in the centers of the second connecting column and the third connecting column. The pin hole is coaxial with the threaded hole and is connected to the threaded hole. The positioning pin is in interference fit with the pin hole; A locking screw is provided in the threaded hole, and the locking screw presses against the end of the positioning pin.

[0013] The preparation method of the above blade root milling cutter includes

[0014] Using a cemented carbide bar as the raw material, machining to obtain a central cylinder and multiple blade segments;

[0015] Performing heat treatment on the central cylinder and the blade segments;

[0016] Sequentially arranging a transition coating, a wear-resistant coating, and a friction-reducing coating on the surface of the blade segments.

[0017] Further, the transition coating is a CrN layer with a thickness of 1 - 2 μm ； The wear-resistant coating is a TiAlN layer with a thickness of 3 - 5 μm ； The friction-reducing coating is a MoS2 layer with a thickness of 0.5 - 1 μm.

[0018] The preparation method of the above blade root milling cutter includes

[0019] Using a cemented carbide bar as the raw material, machining to obtain a central cylinder;

[0020] Using a cemented carbide bar as the raw material, machining to obtain multiple blade segments;

[0021] Heat-treat the central cylinder and the blade segments;

[0022] Successively apply a transition coating, an abrasion-resistant coating, and a friction-reducing coating on the surface of the blade segments;

[0023] Install the blade segments onto the central cylinder.

[0024] Furthermore, taking a cemented carbide bar as the raw material, the process of machining multiple blade segments is as follows:

[0025] Turn the bar to obtain a first blade segment, a second blade segment, and a third blade segment on the surface of the bar, and set cutting allowances at the joints of the first blade segment, the second blade segment, and the third blade segment to obtain a formed blank;

[0026] Milling the formed blank to obtain planes symmetric with respect to the center line on both sides of the center line of the bar;

[0027] Cut the formed blank along the radial direction at the cutting allowances to obtain the first blade segment, the second blade segment, and the third blade segment;

[0028] Mill the cut surfaces of the first blade segment, the second blade segment, and the third blade segment to the designed dimensions.

[0029] The beneficial effects of the present invention are as follows: The present invention divides the original integral formed blade into multiple blade segments, and different blade segments are in different orientations of the central cylinder. When one of the blade segments contacts the blade root of the blade and mills the blade root, the remaining blade segments do not contact the blade root. Therefore, the contact length between the formed blade and the blade root is reduced, the cutting amount of each blade segment is reduced, thereby reducing the cutting resistance, preventing the milling cutter from bending and vibrating significantly, and being beneficial to improving the machining accuracy. At the same time, since each blade segment can form a complete formed blade, the forming requirements can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a front view schematic diagram of the existing milling cutter during milling;

[0031] Figure 2 is Figure 1 the schematic view in the direction of A in

[0032] Figure 3 is a top view schematic diagram of the blade root milling cutter of the present invention;

[0033] Figure 4 is Figure 3 the sectional view taken along B-B in

[0034] Figure 5 is Figure 3 the sectional view taken along C-C in

[0035] Figure 6 is Figure 3 a schematic cross-sectional view of D-D in it;

[0036] Figure 7 is a schematic view when the milling cutter of the present invention is milling;

[0037] Figure 8 is a schematic cross-sectional view of the tool shank of the present invention;

[0038] Figure 9 is a schematic view of the formed blank obtained by turning in the second embodiment;

[0039] Figure 10 is a schematic side view of the formed blank after milling the plane in the second embodiment;

[0040] Figure 11 is a schematic view of the first cutting edge segment obtained by cutting;

[0041] Figure 12 is a schematic view of the second cutting edge segment obtained by cutting;

[0042] Figure 13 is a schematic view of the third cutting edge segment obtained by cutting;

[0043] Reference numerals: 1 - central cylinder; 2 - cutting edge segment; 21 - first cutting edge segment; 22 - second cutting edge segment; 23 - third cutting edge segment; 24 - cutting allowance; 3 - first connecting column; 4 - second connecting column; 5 - third connecting column; 6 - connecting screw; 7 - positioning pin; 8 - locking screw; 10 - tool shank; 13 - damping cavity; 15 - positioning sleeve; 16 - first piezoelectric material layer; 17 - insulating mounting groove; 18 - Peltier effect sheet; 19 - rectifier; 110 - sliding sleeve; 111 - pressing block; 112 - top plate; 113 - second piezoelectric material layer; 114 - flexible sleeve; 115 - rigid block. Detailed implementation manners

[0044] The present invention will be further described below with reference to the drawings and embodiments.

[0045] The blade root milling cutter of the present invention, as Figures 3 to 8 shown, includes a tool shank 10 and a tool head. The tool shank 10 is used to connect the whole milling cutter to the machine tool, and the tool head is used for forming processing of the blade root. Among them, the tool head is as Figures 3 to 6As shown in the figure, it includes a central cylinder 1 and a forming blade disposed on the outer wall of the central cylinder 1. The central cylinder 1 is a cylinder. Each forming blade includes a plurality of blade segments 2. The plurality of blade segments 2 that make up a complete forming blade are evenly distributed in a circular shape around the central cylinder 1, that is, the plurality of blade segments 2 are in different orientations of the central cylinder 1. When one blade segment 2 contacts the blade root, the other blade segments 2 cannot contact the blade root. When the blade segments 2 rotate with the central cylinder 1, each blade segment 2 can sequentially contact the blade root and perform milling on the blade root.

[0046] The plurality of blade segments 2 that make up a complete forming blade are sequentially arranged along the axial direction of the central cylinder 1. And in two adjacent blade segments 2, the opposite end faces of the two blade segments 2 are located in the same plane, and the plane is perpendicular to the central cylinder 1. The outer dimensions of each blade segment 2 are different. With one blade segment 2 unchanged in position and taking the center of the central cylinder 1 as the rotation center, the other blade segments 2 are rotated by a certain angle so that the other blade segments 2 and the blade segment 2 with unchanged position are in the same orientation of the central cylinder 1. Then, each blade segment 2 can be spliced end to end, so as to obtain a complete forming blade, and the outer shape of the forming blade is adapted to the side shape of the fir-tree blade root. During processing, each blade segment 2 rotates with the central cylinder 1 and processes a section of the side surface of the fir-tree blade root respectively. All the blade segments 2 cooperate to meet the processing requirements.

[0047] The processing method of the milling cutter of the present invention for the fir-tree blade root is the same as that of the prior art. Refer to Figure 2 and Figure 7 , the milling cutter feeds from one end (such as the left end in Figure 2 ) of the fir-tree blade root towards the other end (such as the right end in Figure 2 ) and cuts the side surface of the fir-tree blade root to obtain the required shape. Multiple forming milling processes can be adopted, such as twice, to ensure the processing accuracy.

[0048] In the present invention, by dividing the original integral forming blade into a plurality of blade segments 2, different blade segments 2 are in different orientations of the central cylinder 1. When one blade segment 2 contacts the blade root of the blade and mills the blade root, the other blade segments 2 do not contact the blade root. Therefore, the contact length a between the forming blade and the blade root is reduced, the cutting amount of each blade segment 2 is reduced, thereby the cutting resistance can be reduced, preventing the milling cutter from bending and vibrating greatly, which is beneficial to improving the processing accuracy. At the same time, since each blade segment 2 can form a complete forming blade, the forming requirements can be met. Due to the reduction of the cutting resistance and the reduction of the cutting amount of each blade segment 2, in order to ensure the processing efficiency, the rotational speed of the milling cutter can be appropriately increased, thereby increasing the cutting frequency of each blade segment 2.

[0049] The forming blade can be 1 or 2, and each forming blade is divided into a plurality of blade segments 2.

[0050] In the present invention, the number of blade segments 2 can be 2, 3, 4, etc., which is determined according to the height of the forming surface of the longitudinal tree-shaped blade root. As a preferred embodiment, the blade segment 2 includes a first blade segment 21, a second blade segment 22, and a third blade segment 23.

[0051] The overall forming blade can be 1 or 2. Each forming blade is divided into multiple blade segments 2. Specifically, the first blade segment 21, the second blade segment 22, and the third blade segment 23 are all set to be two. And the two first blade segments 21 are centrosymmetric with respect to the central axis of the central column 1, the two second blade segments 22 are centrosymmetric with respect to the central axis of the central column 1, and the two third blade segments 23 are centrosymmetric with respect to the central axis of the central column 1. The two first blade segments 21, the two second blade segments 22, and the two third blade segments 23 are all symmetrically arranged, so that the centers of gravity of the two first blade segments 21, the two second blade segments 22, and the two third blade segments 23 are located at the center of the central column 1, improving the stability during the machining of the milling cutter.

[0052] The first blade segment 21, the second blade segment 22, and the third blade segment 23 can be integrally formed with the central column 1, that is, a bar is used as the raw material, and through processing the bar, the milling cutter of the present invention is obtained. This preparation method can save raw materials and reduce material costs. However, due to the strong irregularity of the structure of the milling cutter of the present invention, the processing difficulty is high, and it is difficult to guarantee the position accuracy of each blade segment 2.

[0053] Therefore, the present invention adopts the method of separately processing the central column 1 and each blade segment 2 and then assembling them. Specifically, the two first blade segments 21 are connected together by the first connecting column 3, the two second blade segments 22 are connected together by the second connecting column 4, and the two third blade segments 23 are connected together by the third connecting column 5. The two first blade segments 21 are integrally formed with the first connecting column 3, the two second blade segments 22 are integrally formed with the second connecting column 4, and the two third blade segments 23 are integrally formed with the third connecting column 5. Therefore, the first blade segment 21, the second blade segment 22, and the third blade segment 23 can be obtained by machining, and each component is integrally in a plate shape, with low processing difficulty and guaranteed processing accuracy.

[0054] The central column 1 is provided with a first positioning groove, a second positioning groove, and a third positioning groove that radially penetrate the central column 1. The first connecting column 3, the second connecting column 4, and the third connecting column 5 are respectively located in the first positioning groove, the second positioning groove, and the third positioning groove, and the first connecting column 3, the second connecting column 4, and the third connecting column 5 are connected to the central column 1 through connecting pieces. The cross-sections of the first positioning groove, the second positioning groove, and the third positioning groove are rectangular, which are regular-shaped grooves with regular shapes. Therefore, the processing difficulty is low and the processing accuracy is guaranteed.

[0055] During assembly, insert the first connecting post 3, the second connecting post 4, and the third connecting post 5 into the first positioning groove, the second positioning groove, and the third positioning groove respectively. The first blade segment 21, the second blade segment 22, and the third blade segment 23 are respectively located outside the first positioning groove, the second positioning groove, and the third positioning groove. At this time, the adjacent sides of the first connecting post 3, the second connecting post 4, and the third connecting post 5 are in contact with each other. Then, position the first connecting post 3, the second connecting post 4, and the third connecting post 5 through a connecting member to ensure the position accuracy and stability of the first blade segment 21, the second blade segment 22, and the third blade segment 23.

[0056] The connecting member includes a connecting screw 6 and a positioning pin 7. The first connecting post 3 is connected to the central column body 1 by two screws 6. A threaded hole is provided in the center of the first connecting post 3. Pin holes are provided in the centers of the second connecting post 4 and the third connecting post 5. The pin holes are coaxial with the threaded hole and are connected to the threaded hole. The positioning pin 7 is in interference fit with the pin hole; a locking screw 8 is provided in the threaded hole, and the locking screw 8 abuts against the end of the positioning pin 7.

[0057] To ensure the stability of the connection, the first blade segment 21, the second blade segment 22, and the third blade segment 23 are arranged in sequence from the milling end to the clamping end. The milling end is the tip of the cutter head, and the clamping end is the handle end. When Figure 7 using the shown processing method, the end face of the first blade segment 21 away from the second blade segment 22 should be flush with the end face of the central column body 1 to meet the processing requirements. At this time, the first positioning groove is located at the end face of the central column body 1. Therefore, fixing the first connecting post 3 to the end of the central column body 1 with two connecting screws 6 can prevent the axial and radial movement of the first connecting post 3 and ensure the stability of the first blade segment 21.

[0058] To ensure the stability of the second connecting post 4 and the third connecting post 5, the positioning pin 7 is in interference fit with the pin holes of the second connecting post 4 and the third connecting post 5. The pin hole can be a frustum-shaped hole, and the positioning pin 7 can be a frustum-shaped pin. In addition, a pin hole can also be provided on the side wall of the third positioning groove away from the second positioning groove. After the positioning pin 7 passes through the pin holes of the second connecting post 4 and the third connecting post 5, it is inserted into the pin hole on the side wall of the second positioning groove. To prevent the positioning pin 7 from loosening, the present invention also uses the locking screw 8 to press the positioning pin 7 tightly.

[0059] The tool shank 10 can adopt various existing tool shank structures. To reduce the vibration during milling, a damping structure is provided inside the tool shank 10 of the milling cutter. Specifically, as Figure 8 shown, a damping cavity 13 is provided inside the tool shank 10. The central column body 1 extends into the damping cavity 13 and is coaxial with the tool shank 10. The central column body 1 can be connected to the tool shank 10 by screws.

[0060] A positioning sleeve 15 is fixedly arranged in the shock absorption cavity 13. The central column 1 is located inside the positioning sleeve 15. The positioning sleeve 15 is coaxial with the central column 1, and a first piezoelectric material layer 16 is arranged between the central column 1 and the positioning sleeve 15. The central column 1 contacts the first piezoelectric material layer 16. When the first piezoelectric material layer 16 is squeezed, a voltage is generated, thereby converting the kinetic energy of vibration into electrical energy.

[0061] A plurality of strip-shaped holes are arranged on the side wall of the shock absorption cavity 13. An insulating installation groove 17 is arranged in each strip-shaped hole. The insulating installation groove 17 can be a plastic groove. A Peltier effect sheet 18 is arranged in each insulating installation groove 17. The Peltier effect sheet 18 includes a plurality of P-type semiconductors and a plurality of N-type semiconductors, and the P-type semiconductors and the N-type semiconductors are arranged alternately. When direct current is passed into the Peltier effect sheet 18, one end of the Peltier effect sheet 18 can absorb the heat from the outside world, and the other end can release heat to the outside world, realizing the transfer of heat. The first piezoelectric material layer 16 is connected to a rectifier 19 through a wire, and the rectifier 19 is connected to the Peltier effect sheet 18 through a wire. The heat absorption end of the Peltier effect sheet 18 faces the inside of the shock absorption cavity 13, and the heat release end of the Peltier effect sheet 18 faces the outside. Since the first piezoelectric material layer 16 generates alternating current, the rectifier 19 is used to convert the alternating current into direct current to meet the working requirements of the Peltier effect sheet 18. The insulating installation groove 17 can prevent the Peltier effect sheet 18 from leaking electricity, and the positioning sleeve 15 can also be an insulating sleeve.

[0062] When the central column 1 vibrates, the vibration kinetic energy of the central column 1 is converted into alternating current through the first piezoelectric material layer 16. After the alternating current is rectified into direct current by the rectifier 19, it is transmitted to the Peltier effect sheet 18. The Peltier effect sheet 18 absorbs the heat inside the tool shank 10 and releases the heat outside the tool shank 10, realizing the heat dissipation of the tool shank 10.

[0063] During cutting, a large amount of heat is generated in each cutting edge section 2. Part of the heat is carried away by the cutting fluid, but part of the heat is transferred to the tool shank 10, and it is difficult for the heat inside the tool shank 10 to dissipate. In the present invention, the first piezoelectric material layer 16, the rectifier 19 and the Peltier effect sheet 18 form a piezoresistive damping device, which can effectively reduce the vibration of the anti-seismic central column 1, and at the same time can promote the heat dissipation inside the tool shank 10, preventing the temperature inside the tool shank 10 from being too high and affecting the strength.

[0064] In the present invention, the first piezoelectric material layer 16 can be made of piezoelectric ceramics, preferably a polyvinylidene fluoride film. The polyvinylidene fluoride film is a flexible film with a large deformation amount and a low impedance, and can generate a higher voltage.

[0065] In order to increase the electrical energy supplied to the Peltier effect sheet 18 and enhance the heat dissipation effect, a plurality of radially extending sliding sleeves 110 are provided on the outer wall of the positioning sleeve 15. A pressing block 111 that is slidably engaged with the sliding sleeve 110 is provided inside the sliding sleeve 110. A top plate 112 is fixedly provided at the top end of the sliding sleeve 110. A second piezoelectric material layer 113 is provided on the inner side wall of the top plate 112. The second piezoelectric material layer 113 can also be made of a polyvinylidene fluoride film. The second piezoelectric material layer 113 is connected to the rectifier 19 through a wire; a plurality of air holes are provided on the side wall of the sliding sleeve 110. During milling, the tool shank 10 rotates at a high speed, and the pressing block 111 is subjected to a centrifugal force, so that it slides along the sliding sleeve 110 to the inside of the top plate 112. The centrifugal force of the pressing block 111 is transmitted to the second piezoelectric material layer 113. After being pressed, the second piezoelectric material layer 113 will also generate electrical energy. The electrical energy generated by the second piezoelectric material layer 113 is transmitted to the Peltier effect sheet 18, increasing the current passing through the Peltier effect sheet 18 and improving the heat absorption and heat release efficiency.

[0066] A flexible sleeve 114 is sleeved outside the central column 1. The flexible sleeve 114 can be made of a rubber sleeve. A plurality of positioning grooves are provided on the flexible sleeve 114, and a plurality of rigid blocks 115 are provided in the positioning grooves. The rigid blocks 115 contact the first piezoelectric material layer 16. The central column 1 is made of a metal material with relatively high hardness and strength, and has a relatively small amplitude during vibration. After the flexible sleeve 114 is sleeved outside the central column 1, when the central column 1 vibrates, it drives the flexible sleeve 114 to vibrate, and the rigid blocks 115 vibrate along with the flexible sleeve 114. The vibration movement can be regarded as a small-distance movement. Since the flexible sleeve 114 has low strength and is easy to deform, when the flexible sleeve 114 moves a small distance in a certain direction and then stops moving, the rigid blocks 115 will continue to move a small distance under the action of inertia, and at the same time pull the flexible sleeve 114 to deform. Therefore, the vibration amplitude of the rigid blocks 115 will be greater than that of the flexible sleeve 114, so as to more effectively squeeze the first piezoelectric material layer 16 and ensure the power generation effect of the first piezoelectric material layer 16. In addition, the elastic deformation of the flexible sleeve 114 itself can absorb the energy during vibration and optimize the damping effect.

[0067] Embodiment 1

[0068] The preparation method of the blade root milling cutter of the present invention includes

[0069] Using a cemented carbide bar as the raw material, the central column 1 and a plurality of blade segments 2 are obtained by machining. The cemented carbide can specifically be tungsten-cobalt-based cemented carbide, with grades such as YG3, YG6, YG8, etc.

[0070] Performing heat treatment on the central column 1 and the blade segments 2. An existing heat treatment process can be used to increase the hardness of the blade segments 2.

[0071] A transition coating, a wear-resistant coating, and a friction-reducing coating are sequentially provided on the surface of the blade segment 2. The transition coating uses a high-adhesion material to enhance the bonding force between the coating and the substrate; the wear-resistant coating uses a wear-resistant material to improve the wear resistance and cutting performance of the blade segment 2; the friction-reducing coating uses a self-lubricating material to reduce the frictional resistance during cutting. Specifically, the transition coating is a CrN layer with a thickness of 1-2 μm ； The wear-resistant coating is a TiAlN layer with a thickness of 3-5 μm ； The friction-reducing coating is a MoS2 layer with a thickness of 0.5-1 μm.

[0072] The advantages of this embodiment are that only one hard alloy bar is required as the raw material, saving raw materials, and the central column 1 and the multiple blade segments 2 are integrally formed with high connection strength. The disadvantages are that the milling cutter structure has strong irregularity, high processing difficulty, and it is difficult to ensure the position accuracy of each blade segment 2.

[0073] Embodiment Two

[0074] The preparation method of this embodiment includes

[0075] Using a hard alloy bar as the raw material, the central column 1 is obtained by machining. The hard alloy can specifically be tungsten-cobalt hard alloy with grades such as YG3, YG6, YG8, etc. The central column 1 is a standard cylinder with low processing difficulty and can ensure processing accuracy. After processing, a first positioning groove, a second positioning groove, a third positioning groove, a pin hole, and a threaded connection hole are opened on the central column 1.

[0076] Using a hard alloy bar as the raw material, multiple blade segments 2 are obtained by machining. The material of the blade segment 2 can be the same as or different from that of the central column 1. For example, the blade segment 2 can use a material with higher hardness. The blade segment 2 can be obtained by milling. As a preferred embodiment:

[0077] The specific processing process of the blade segment 2 is as follows:

[0078] The bar is turned, and a first blade segment 21, a second blade segment 22, and a third blade segment 23 are obtained on the surface of the bar. A cutting allowance 24 is provided at the connection of the first blade segment 21, the second blade segment 22, and the third blade segment 23 to obtain a formed blank, as Figure 9 shown. Forming the outer shapes of the first blade segment 21, the second blade segment 22, and the third blade segment 23 simultaneously can improve processing efficiency and ensure the symmetry of the two first blade segments 21. The cutting allowance 24 is in a regular cylindrical shape. In subsequent processes, after the blank is cut, a certain length of material will be consumed. Therefore, an appropriate amount of cutting allowance 24 is reserved to avoid that the first blade segment 21, the second blade segment 22, and the third blade segment 23 cannot be spliced into a complete formed blade after cutting. At the same time, the surface roughness during cutting is low, and a certain amount of finishing allowance is reserved.

[0079] The formed blank is milled to obtain planes symmetrical with respect to the center line on both sides of the center line of the bar, as Figure 10 shown. The formed blank after milling is in a plate shape.

[0080] The formed blank is cut along the radial direction at the cutting allowance 24 to obtain a first cutting edge segment 21 as Figure 11 shown, Figure 12 a second cutting edge segment 22 as Figure 13 shown, and

[0081] a third cutting edge segment 23 as

[0082] shown. There are two of each of the first cutting edge segment 21, the second cutting edge segment 22, and the third cutting edge segment 23, and at the same time, a first connecting column 3, a second connecting column 4, and a third connecting column 5 are obtained.

[0083] The cut surfaces of the first cutting edge segment 21, the second cutting edge segment 22, and the third cutting edge segment 23 are milled to the designed dimensions.

[0084] Then, pin holes are machined at the centers of the second connecting column 4 and the third connecting column 5, a threaded hole is machined at the center of the first connecting column 3, and smooth holes are machined on both sides of the threaded hole.

[0085] The cutting edge segment 2 is installed on the central column body 1.

[0086] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Blade root milling cutter, comprising a cutter bar (10) and a cutter head, the cutter head including a central column (1) and a formed cutting edge provided on the outer wall of the central column (1), characterized in that: Each of the formed cutting edges includes a plurality of cutting edge segments (2), the plurality of cutting edge segments (2) are evenly distributed in a circumferential shape around the central column (1), and the plurality of cutting edge segments (2) are sequentially arranged along the axial direction of the central column (1); Among two adjacent cutting edge segments (2), the end faces of the two cutting edge segments (2) facing each other are located in the same plane, and the plane is perpendicular to the central column (1); The cutting edge segment (2) includes a first cutting edge segment (21), a second cutting edge segment (22) and a third cutting edge segment (23); There are two of the first cutting edge segments (21), the second cutting edge segments (22) and the third cutting edge segments (23) respectively, and the two first cutting edge segments (21) are centrosymmetric with respect to the center line of the central column (1), the two second cutting edge segments (22) are centrosymmetric with respect to the center line of the central column (1), and the two third cutting edge segments (23) are centrosymmetric with respect to the center line of the central column (1); The two first cutting edge segments (21) are connected into one body by a first connecting column (3), the two second cutting edge segments (22) are connected into one body by a second connecting column (4), and the two third cutting edge segments (23) are connected into one body by a third connecting column (5); The central column (1) is provided with a first positioning groove, a second positioning groove and a third positioning groove radially penetrating the central column (1), the first connecting column (3), the second connecting column (4) and the third connecting column (5) are respectively located in the first positioning groove, the second positioning groove and the third positioning groove, and the first connecting column (3), the second connecting column (4) and the third connecting column (5) are connected to the central column (1) through a connecting member; The first cutting edge segment (21), the second cutting edge segment (22) and the third cutting edge segment (23) are sequentially arranged from the milling end to the clamping end, the connecting member includes a connecting screw (6) and a positioning pin (7), the first connecting column (3) is connected to the central column (1) by two screws (6), a threaded hole is provided in the center of the first connecting column (3), a pin hole is provided in the centers of the second connecting column (4) and the third connecting column (5), the pin hole is coaxial with the threaded hole, and the pin hole is connected to the threaded hole, and the positioning pin (7) is in interference fit with the pin hole; a locking screw (8) is provided in the threaded hole, and the locking screw (8) presses against the end of the positioning pin (7); A damping cavity (13) is provided inside the cutter bar (10), the central column (1) extends into the damping cavity (13), and the central column (1) is coaxial with the cutter bar (10), and the central column (1) is connected to the cutter bar (10) by screws; A positioning sleeve (15) is fixedly provided in the damping cavity (13), the central column (1) is located inside the positioning sleeve (15), the positioning sleeve (15) is coaxial with the central column (1), and a first piezoelectric material layer (16) is provided between the central column (1) and the positioning sleeve (15), and the central column (1) contacts the first piezoelectric material layer (16); The side wall of the shock absorption cavity (13) is provided with a plurality of strip-shaped holes, each strip-shaped hole is provided with an insulating mounting groove (17), each insulating mounting groove (17) is provided with a Peltier effect sheet (18), the Peltier effect sheet (18) includes a plurality of P-type semiconductors and a plurality of N-type semiconductors, the P-type semiconductors and the N-type semiconductors are arranged alternately, the first piezoelectric material layer (16) is connected with a rectifier (19) through a wire, the rectifier (19) is connected with the Peltier effect sheet (18) through a wire, the heat absorption end of the Peltier effect sheet (18) faces the inside of the shock absorption cavity (13), and the heat release end of the Peltier effect sheet (18) faces the outside.

2. The preparation method of the blade root milling cutter according to claim 1, characterized in that: Include Using a cemented carbide bar as the raw material, machining to obtain a central column body (1) and a plurality of blade segments (2); Performing heat treatment on the central column body (1) and the blade segments (2); Sequentially arranging a transition coating, a wear-resistant coating and a friction-reducing coating on the surface of the blade segments (2).

3. The preparation method according to claim 2, characterized in that: The transition coating is a CrN layer with a thickness of 1-2 μm; the wear-resistant coating is a TiAlN layer with a thickness of 3-5 μm; the friction-reducing coating is a MoS2 layer with a thickness of 0.5-1 μm.

4. The preparation method of the blade root milling cutter according to claim 1, characterized in that: Include Using a cemented carbide bar as the raw material, machining to obtain a central column body (1); Using a cemented carbide bar as the raw material, machining to obtain a plurality of blade segments (2); Performing heat treatment on the central column body (1) and the blade segments (2); Sequentially arranging a transition coating, a wear-resistant coating and a friction-reducing coating on the surface of the blade segments (2); Installing the blade segments (2) onto the central column body (1).

5. The preparation method according to claim 4, characterized in that: The process of machining a plurality of blade segments (2) using a cemented carbide bar as the raw material is as follows: Performing turning on the bar to obtain a first blade segment (21), a second blade segment (22) and a third blade segment (23) on the surface of the bar, a cutting allowance (24) is provided at the connection of the first blade segment (21), the second blade segment (22) and the third blade segment (23) to obtain a formed blank; Performing milling on the formed blank to obtain planes symmetrical with respect to the center line on both sides of the bar center line; Cutting the formed blank along the radial direction at the cutting allowance (24) to obtain the first blade segment (21), the second blade segment (22) and the third blade segment (23); Milling the cut surfaces of the first blade segment (21), the second blade segment (22) and the third blade segment (23) to the designed dimensions.

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