Numerical control cutter for valve seat machining

Abstract

The invention provides a numerical control tool for valve seat machining, and relates to the technical field of valve seat machining tools. The numerical control tool for valve seat machining comprises a tool body and a connecting piece, the tool body comprises a tool body and a tool bit which are coaxially and fixedly connected, a spiral channel is formed in the tool body in the axial direction, a balancing weight is arranged in the spiral channel in a sliding mode, a power assembly is coaxially arranged in a connecting pipe and a connecting cap, and the power assembly comprises a spiral column. The spiral column is inserted into the spiral channel in a sliding mode, energy generated by flutter is converted into heat energy through friction between the balancing weight and the spiral channel, the heat energy is dissipated through the cutter body, and the machining precision of the sealing face of the valve seat is improved. The length of the spiral channel is changed through displacement of the spiral column, so that the lead of the spiral channel is linked with the rotating speed of the cutter body, it is ensured that the damping direction of the balancing weight is always opposite to the flutter direction at different rotating speeds, and the device is suitable for suppressing flutter of the cutter body at different rotating speeds.

Description

Technical Field

[0001] This application relates to the field of valve seat machining tool technology, and more specifically, to a CNC tool for valve seat machining. Background Technology

[0002] The machining of valve seat sealing surfaces requires high-speed cutting. Existing cutting tools are prone to "chatter" due to the imbalance between tool rigidity and vibration suppression, resulting in ripples on the machined valve seat sealing surfaces and shortening tool life. Summary of the Invention

[0003] This application aims to at least solve one of the technical problems existing in the prior art. To this end, this application proposes a CNC cutting tool for valve seat machining, comprising a tool body and a connecting member. The tool body includes a tool tip and a cutter head coaxially fixed together. The connecting member includes a connecting pipe, a connecting cap, and an end cap coaxially fixed together. The tool tip is fixed to the connecting pipe via the end cap. A helical channel is axially arranged inside the tool body. A counterweight is slidably arranged within the helical channel. A power assembly is coaxially arranged within the connecting pipe and the connecting cap. The power assembly includes a micro servo motor. The output end of the micro servo motor is keyed to a drive shaft. A disk is keyed to the drive shaft. A helical column is slidably connected to the end of the disk. The helical column is slidably inserted into the helical channel. The helical column can slide along the helical channel driven by the micro servo motor to achieve changes in the length of the helical channel.

[0004] Preferably, a flat portion is provided on the side wall of one end of the blade, and the flat portion is adapted to the inner wall of the connecting cap.

[0005] Preferably, the connecting tube has a hollow cavity, the end has a recessed cavity, the recessed cavity and the hollow cavity are coaxially connected, and the micro servo motor is fixed to the recessed cavity.

[0006] Preferably, the spiral channel has a rectangular cross-section, and each of the four side walls of the spiral channel is fitted with an arc-shaped groove.

[0007] Preferably, the counterweight has a rectangular cross-section, and the counterweight includes two rectangular end portions and four side portions.

[0008] Preferably, a plurality of balls are uniformly embedded on the side surface, and the plurality of balls roll in the arc-shaped groove on the side wall of the spiral channel.

[0009] Preferably, the four sets of balls on the periphery of the counterweight are respectively fitted with the arc-shaped grooves on the corresponding sidewalls of the spiral channel.

[0010] Preferably, a buffer element is embedded on the end face, the buffer element comprising a rubber pillar and a rubber block, the rubber pillar being embedded in the end face, the rubber block being fixed to the rubber pillar, and the rubber block not abutting against the side wall of the spiral channel.

[0011] Preferably, a rotating cavity is provided at one end of the disk.

[0012] Preferably, one end of the spiral column is fixedly connected to a protrusion, and the protrusion rotates within the rotating cavity.

[0013] The beneficial effects of this invention are: 1. When the tool body chatters, the counterweight will move in the opposite direction to the tool body in the spiral channel due to inertia. The friction between the counterweight and the spiral channel will convert the energy generated by the chatter into heat energy, which will be dissipated through the tool body, thereby reducing the vibration energy of the chatter and improving the machining accuracy of the valve seat sealing surface. 2. A micro servo motor drives the disk to rotate, causing the helical column to move along the helical channel. This changes the length of the helical channel, making the lead of the helical channel and the rotation speed of the tool body linked. This ensures that the damping direction of the counterweight is always opposite to the chatter direction at different speeds, thus making it suitable for suppressing tool body chatter at different speeds.

[0014] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall structure of a CNC tool for machining valve seats according to an embodiment of this application; Figure 2 This is a cross-sectional view of a CNC cutting tool for machining a valve seat according to an embodiment of this application; Figure 3 This is a partial structural cross-sectional view of a CNC tool for machining valve seats according to an embodiment of this application; Figure 4 This is a schematic diagram of a spiral channel according to an embodiment of this application; Figure 5 This is a partial exploded view of a CNC tool for machining valve seats according to an embodiment of this application; Figure 6 This is a schematic diagram of the structure of the counterweight according to an embodiment of this application; Figure 7 This is an exploded view of the power assembly according to an embodiment of this application; Figure 8 This is an exploded view of the positioning structure according to an embodiment of this application; Figure 9 This is a schematic diagram of the installation position of the positioning component according to an embodiment of this application. Figure 1 ; Figure 10 This is a schematic diagram of the positioning component according to an embodiment of this application; Figure 11 This is a schematic diagram of the installation position of the positioning component according to an embodiment of this application. Figure 2 ; Figure 12 According to the embodiments of this application Figure 11 Enlarged view of A in the middle; Figure 13 This is a schematic diagram of the installation position of the sealing plug according to an embodiment of this application; Figure 14 This is a schematic diagram of the location of the linkage channel according to an embodiment of this application.

[0017] Reference numerals: 1. Cutter body; 11. Cutter blade; 111. Helical channel; 112. Mounting chamber; 113. Shaft channel; 114. Flat part; 115. Radial through hole; 116. Protrusion; 117. Arc-shaped notch; 118. Arc-shaped rotary groove; 12. Cutter head; 2. Connecting piece; 21. Connecting pipe; 211. Hollow cavity; 22. Connecting cap; 23. End; 231. Recessed cavity; 3. Counterweight; 31. End face; 32. Side face; 33. Ball bearing; 34. Buffer; 341. Rubber column; 342. Rubber block; 4. Power assembly; 41 42. Miniature servo motor; 43. Drive shaft; 44. Disc; 45. Rotating cavity; 46. Spiral column; 47. Protrusion; 58. Positioning structure; 59. Sealing block; 50. Central recess; 51. Conical recess; 52. Sealing surface; 53. Recessed surface; 54. Positioning protrusion; 55. Central protrusion; 56. Conical protrusion; 57. Positioning assembly; 58. Pin rod; 59. Positioning rod; 50. Arc groove; 51. Fixing block; 52. Sliding block; 53. Arc tube; 54. Spring; 55. Sealing plug; 66. Linkage channel. Detailed Implementation

[0018] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] Example 1, as Figures 1-7 As shown, a CNC cutting tool for machining valve seats according to an embodiment of this application includes a tool body 1 and a connecting member 2. The tool body 1 includes a tool body 11 and a tool tip 12 that are coaxially fixed. The connecting member 2 includes a connecting pipe 21, a connecting cap 22 and an end 23 that are coaxially fixed. The tool body 11 is fixed to the connecting pipe 21 through the end 23.

[0021] Among them, such as Figure 5 As shown, a flat portion 114 is provided on the side wall of one end of the blade 11. The flat portion 114 is adapted to the inner wall of the connecting cap 22, and a protrusion is provided at the end of the blade 11 with the flat portion 114. A corresponding recess is provided on the inner side of the connecting cap 22. It can be understood that the blade 11 passes through the connecting cap 22. Through the adaptation relationship between the flat portion 114 and the inner wall of the connecting cap 22, rotation restriction can be formed between the blade 11 and the connecting cap 22. The protrusion at the end of the blade 11 and the recess inside the connecting cap 22 can form axial positioning between the two. Figure 2 and Figure 3 As shown, the connecting cap 22 and the connecting pipe 21 can be coaxially fixed together by a flange. Similarly, the connecting pipe 21 and the end 23 are coaxially fixed together by a flange.

[0022] like Figure 2 and Figure 3 As shown, a hollow cavity 211 is provided inside the connecting pipe 21, and a recessed cavity 231 is provided inside the end 23. The recessed cavity 231 and the hollow cavity 211 are coaxially connected.

[0023] like Figure 2 and Figure 3 As shown, a spiral channel 111 is arranged axially inside the blade 11. A counterweight 3 is slidably arranged inside the spiral channel 111. A power assembly 4 is coaxially arranged inside the connecting pipe 21 and the connecting cap 22. The power assembly 4 includes a micro servo motor 41, which is fixed to the recessed cavity 231. The output end of the micro servo motor 41 is keyed to a drive shaft 42. A disk 43 is keyed to the drive shaft 42. A spiral column 44 is slidably connected to the end of the disk 43. The spiral column 44 is slidably inserted into the spiral channel 111. The spiral column 44 can slide along the spiral channel 111 driven by the micro servo motor 41 to realize the length change of the spiral channel 111.

[0024] It should be noted that, as Figure 4 As shown, the cross-section of the spiral channel 111 is rectangular, and the four side walls of the spiral channel 111 are respectively fitted with arc-shaped grooves.

[0025] like Figure 6 As shown, the counterweight 3 has a rectangular cross-section and includes two rectangular end portions 31 and four side portions 32. Multiple balls 33 are evenly embedded on the side portions 32. The multiple balls 33 roll in the arc-shaped grooves on the side wall of the spiral channel 111. Furthermore, the four sets of balls 33 on the periphery of the counterweight 3 respectively have clearance fits with the arc-shaped grooves on the corresponding side wall of the spiral channel 111.

[0026] Thus, the counterweight 3 can undergo slight radial displacement within the spiral channel 111.

[0027] It should be noted that the rectangular cross-section of the spiral channel 111 and the counterweight 3 makes it easier to constrain the torsional motion of the counterweight 3 than a circular cross-section, thus suppressing the torsional chatter of the valve seat sealing surface.

[0028] It should be further noted that in the specific embodiments of this application, the counterweight 3 is made of tungsten steel. The high density of tungsten steel can increase the weight of the counterweight 3 without changing its volume, so as to achieve high inertia. Tungsten steel has high hardness, thus improving wear resistance and making it suitable for high-speed conditions. It also prevents the counterweight 3 from deforming and improves the practicality of the counterweight 3.

[0029] Furthermore, a buffer 34 is embedded on the end face 31. The buffer 34 includes a rubber pillar 341 and a rubber block 342. The rubber pillar 341 is embedded in the end face 31, and the rubber block 342 is fixed to the rubber pillar 341. The rubber block 342 does not abut against the side wall of the spiral channel 111.

[0030] It is understandable that when the counterweight 3 is displaced to the end of the spiral channel 111, the rubber block 342 will come into contact with the obstruction at the end of the spiral channel 111. In this way, the rubber block 342 and the rubber column 341 will be compressed, forming a certain buffering effect.

[0031] Furthermore, it can be understood that during actual use, when the cutter head 12 cuts the valve seat sealing surface (the cutter body 1 rotates), radial chatter will occur due to uneven material hardness, meaning the cutter body 1 will shift outwards. Simultaneously, axial movement will also occur, meaning the cutter body 1 will move back and forth. The rotation of the cutter body 1 will cause the spiral channel 111 inside the cutter body 11 to rotate synchronously. Therefore, under inertia, the counterweight 3 will move along the reverse trajectory of the spiral channel 111. It should be noted that the inertial force of the counterweight 3 needs to be greater than the chattering force. Further, it should be noted that the counterweight 3 moves along the reverse trajectory of the spiral channel 111. The motion is as follows: when the cutter body 1 shifts outward, the counterweight 3 moves inward; when the cutter body 1 moves forward, the counterweight 3 moves backward. During this process, the ball bearing 33 rolls in the arc-shaped groove in the spiral channel 111. The damping torque generated by the rolling friction will convert some of the vibration energy into frictional heat. At the same time, when the counterweight 3 runs to the end of the spiral channel 111, the rubber column 341 and the rubber block 342 are squeezed. Through the deformation of the rubber column 341 and the rubber block 342, most of the vibration energy is converted into heat energy. In this way, the heat energy formed after the vibration energy is converted can be dissipated through the cutter body 11 and cooled by the cutting fluid.

[0032] It should also be noted that, as Figure 7 As shown, a rotating cavity 431 is provided at one end of the disk 43, and a protrusion 441 is fixedly connected to one end of the spiral column 44. The protrusion 441 rotates in the rotating cavity 431.

[0033] It should be noted that the rotating cavity 431 and the spiral column 44 are eccentrically positioned relative to the disk 43.

[0034] Therefore, it can be understood that after the micro servo motor 41 starts, it will drive the drive shaft 42 to rotate, which in turn drives the disk 43 to rotate. During the rotation of the disk 43, the spiral column 44 will rotate around the drive shaft 42. Since the spiral column 44 is slidably inserted into the spiral channel 111, when the spiral column 44 rotates around the drive shaft 42, it will create displacement between itself and the spiral channel 111 and rotate within the rotating cavity 431 to prevent motion interference. When the spiral column 44 moves along the spiral channel 111, it will... The axial limiting relationship between its own protrusion 441 and the rotating cavity 431 causes the disk 43 to slide on the drive shaft 42. It should be noted that the micro servo motor 41 in this application has forward and reverse rotation functions. Therefore, it can be understood that by rotating the micro servo motor 41 in the forward and reverse directions, the stroke of the helical column 44 in the helical channel 111 can be realized. That is, the stroke of the inner cavity of the helical channel 111 can be adjusted to adapt the damping direction of the counterweight 3 at different speeds to always be opposite to the chatter direction, so that the counterweight 3 can be used to suppress the chatter of the tool body 1 at different speeds.

[0035] Meanwhile, the arc-shaped groove provides a movement track for the ball 33, avoiding direct friction between the counterweight 3 and the cavity wall of the spiral channel 111, thereby reducing wear and deformation.

[0036] In addition, the spiral channel 111 extends to the middle section of the blade 11, which can avoid the occurrence of distal chatter and further improve the chatter suppression effect of the entire blade 1.

[0037] It should be further noted that in this application, a conductive slip ring can be fitted at the end 23. The rotating end of the conductive slip ring is fitted on the end 23, and the fixed end of the conductive slip ring is fixed to an external fixed device. The power supply of the micro servo motor 41 passes through the side wall of the end 23 and is connected to the conductive slip ring, thus satisfying the normal power supply of the micro servo motor 41.

[0038] In summary, it can be understood that this design of the present application, through the ball bearings 33 on the counterweight 3 and the buffers 34 at both ends, as well as the inertia of the counterweight 3 itself, can work with the spiral channel 111 to form a reverse damping effect at different speeds, converting vibration energy into heat energy and dissipating it, thereby reducing the occurrence of chattering of the tool body 1 during valve seat machining and improving the machining accuracy of the valve seat sealing surface.

[0039] In related technologies, the CNC cutting tool used for valve seat machining often needs to be replaced with a suitable tool due to differences in the size, precision, and finish of the valve seat sealing surface, or because different valve seats are used. In the prior art, the entire tool body 1 needs to be replaced, resulting in low tool changing efficiency in the process and affecting the overall machining efficiency.

[0040] Example 2, according to some embodiments of this application, such as Figure 2 , Figure 3 , Figures 8-12 As shown, a positioning structure 5 is provided between the blade body 11 and the blade head 12. The positioning structure 5 includes a sealing block 51 that is coaxially sealed and slides on the end of the blade body 11, a positioning protrusion 52 that is fixed to the blade head 12, and a radially arranged positioning component 53. An installation chamber 112 is provided at the end of the blade body 11. The sealing block 51 is sealed and slides on the installation chamber 112. A shaft channel 113 is coaxially arranged inside the blade body 11. The shaft channel 113 is connected to the installation chamber 112 and externally connected to an oil supply device. A radial through hole 115 is provided on the side wall of the blade body 11. The positioning component 53 is sequentially inserted into the radial through hole 115, the sealing block 51, and then the positioning protrusion 52 to fix the blade head 12 to the blade body 11.

[0041] It should be noted that the blade 11, the connecting tube 21, and the connecting cap 22 are in a relatively fixed state. Therefore, the axial channel 113 can be provided with an oil inlet passage in the radial direction. This oil inlet passage can be provided on the side wall of the connecting cap 22 or the side wall of the connecting tube 21, as long as it does not obstruct the spiral column 44.

[0042] The installation compartment 112 has a rectangular cross-section so that the sealing block 51 can only be displaced axially, and the open end of the installation compartment 112 is provided with a protrusion 116.

[0043] Specifically, the end face of the sealing block 51 is provided with a central recess 511 and multiple conical recesses 512. The side wall of the sealing block 51 includes a sealing surface 513 and a recessed surface 514. The sealing surface 513 and the inner wall of the mounting chamber 112 are in a sealing sliding fit, and the recessed surface 514 and the protrusion 116 are in a clearance fit.

[0044] Therefore, it can be seen that the sealing block 51 can only undergo axial displacement within the installation chamber 112, and the protrusion 116 can prevent the sealing block 51 from detaching from the installation chamber 112.

[0045] Furthermore, the positioning bump 52 includes a central bump 521 and a plurality of conical bumps 522. The central bump 521 is inserted into the central recess 511, and the plurality of conical bumps 522 are respectively inserted into the plurality of conical recesses 512.

[0046] It should be noted that after oil is injected into the shaft channel 113, it will push the sealing block 51 to move outward, and make the positioning protrusion 52 and the corresponding central recess 511 and conical recess 512 form a tight fit, resulting in an interference fit. At the same time, it should be noted that at this time, the end face of the sealing block 51 and the end face of the cutter head 12 are in close contact.

[0047] It is understandable that the interlocking relationship between the tapered protrusion 522 and the tapered recess 512 can reduce the radial clearance between the cutter head 12 and the cutter body 11, improve positioning accuracy, improve axial rigidity, and improve torsional resistance.

[0048] Additionally, the positioning component 53 includes a pin 531, which is inserted into the central protrusion 521. A positioning rod 532 is coaxially fixed to the end of the pin 531. The diameter of the positioning rod 532 is larger than that of the pin 531. An arc-shaped groove 533 and a fixing block 534 are provided on the side wall of the positioning rod 532. A sliding block 535 is slidably connected in the arc-shaped groove 533. An arc-shaped tube 536 is fixed to the side wall of the sliding block 535. An arc-shaped spring 537 is fixed between the sliding block 535 and the fixing block 534. One end of the spring 537 is inserted into the arc-shaped tube 536.

[0049] like Figure 12 As shown, an arc-shaped notch 117 is provided at the outward end of the radial through hole 115, and an arc-shaped rotating groove 118 is provided on the inward side of the arc-shaped notch 117. The arc of the arc-shaped rotating groove 118 is greater than the arc of the arc-shaped notch 117. The fixing block 534, the sliding block 535 and the arc-shaped tube 536 are slidably disposed in the arc-shaped rotating groove 118.

[0050] It should be noted that the radial through hole 115 is located at the end of the sealing block 51 that faces the opening of the installation compartment 112 during the displacement stroke, and when the sealing block 51 is displaced to its limit, the side wall of the sealing block 51 covers the radial through hole 115.

[0051] Therefore, the cutting head 12 and the cutting body 11 in use are immediately axially positioned by the pin 531 inserted into the central protrusion 521. Rotation is restricted between the central recess 511 and the central protrusion 521, and between the conical recess 512 and the conical protrusion 522. The pin 531, through its end spring 537, rotates the fixing block 534 to a position where the arc-shaped rotating groove 118 is axially offset from the arc-shaped notch 117, achieving axial positioning. When the cutting head 12 needs to be replaced, the positioning rod 532 is rotated, causing the fixing block 534 to rotate along the arc-shaped rotating groove 118 to the position of the arc-shaped notch 117. At this time, the spring 537 is compressed, and then the entire positioning assembly 53 is pulled out axially. At this point, the positioning assembly 53 loses its locking ability on the cutting head 12, and the cutting head 12 can be directly replaced. When installing other cutting heads 12, oil is injected into the installation chamber 112 through the external oil supply assembly, causing the sealing block 5... 1. Displace outwards, and then insert the cutter head 12 directly into the sealing block 51 along the axial direction. Then insert the pin rod 531 along the radial through hole 115 and insert the pin rod 531 into the central protrusion 521. When inserting the pin rod 531, first rotate the pin rod 531 so that the fixing block 534 and the sliding block 535 are both located in the arc-shaped notch 117. After it is inserted to the bottom, release the pressure on the spring 537. With the reset of the spring 537, the fixing block 534 can drive the entire pin rod 531 and the positioning rod 532 to rotate. The fixing block 534 rotates to the position where the arc-shaped rotating groove 118 is disengaged from the arc-shaped notch 117, thus realizing the positioning of the positioning component 53 in the radial through hole 115. The whole process takes relatively little time, improves the efficiency of tool changing, and forms a double positioning of conical surface and end face between the cutter head 12 and the sealing block 51 in the cutter body 11, which improves axial rigidity and torsional resistance and reduces radial clearance.

[0052] In the relevant technology, the CNC tool for machining valve seats has a problem where the counterweight 3 will be displaced in the spiral channel 111 during the rotation of the tool body 1. Even though ball bearings 33 are used between the counterweight 3 and the spiral channel 111 to reduce wear, frequent use will still cause wear on the ball bearings 33. Once wear produces debris, it will aggravate the wear of the ball bearings 33 and affect the actual use effect of the counterweight 3.

[0053] Example 3, according to some embodiments of this application, such as Figure 13 and Figure 14As shown, the end of the spiral channel 111 away from the cutter head 12 is sealed with a sealing plug 6, and the spiral column 44 is slidably inserted into the sealing plug 6. The end of the cutter body 11 facing the cutter head 12 is provided with a linkage channel 7, which is connected to the spiral channel 111 and the mounting chamber 112 respectively.

[0054] Therefore, in practical use, when an external oil supply device injects oil into the installation chamber 112, the oil will exert a certain pressure on the sealing block 51, causing it to move to the open end of the installation chamber 112 and form a tight fit with the cutter head 12. At this time, due to the setting of the linkage channel 7, some oil will enter the spiral channel 111 from the installation chamber 112 and fill the entire spiral channel 111 (the sealing plug 6 seals the spiral channel 111 at the other end). Thus, the entire spiral channel 111 will be filled with oil under certain pressure. The pressurized oil will form a fluid lubrication film between the counterweight 3 and the spiral channel 111, reducing the pressure on the ball bearings 33 on the counterweight 3. The friction between the counterweight 3 and the wall of the spiral channel 111 reduces the wear of the ball bearing 33. At the same time, the oil filling the spiral channel 111 can further disperse the heat generated between the counterweight 3 and the spiral channel 111 into the oil throughout the spiral channel 111 and diffuse it to the outside of the blade 11, thus improving the heat dissipation effect. In addition, when changing the blade head 12, in order to release pressure, the external oil supply device will cancel the pressure or recover part of the oil. In this way, the debris in the spiral channel 111 will also be carried away by the oil, thereby further reducing the wear of the ball bearing 33. Thus, this design improves the service life of the counterweight 3 and improves the energy consumption efficiency, that is, improves the chatter suppression effect.

[0055] It should be noted that the specific models and specifications of the ball bearing 33, rubber column 341, micro servo motor 41 and spring 537 need to be selected and determined according to the actual specifications of the device. The specific selection calculation method adopts the existing technology in this field, so it will not be described in detail.

[0056] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A numerical control cutter for valve seat machining, comprising a cutter body (1) and a connecting piece (2), the cutter body (1) comprising a cutter body (11) and a cutter head (12) coaxially fixed, the connecting piece (2) comprising a connecting pipe (21), a connecting cap (22) and an end head (23) coaxially fixed, the cutter body (11) being fixed through the end head (23) and the connecting pipe (21), characterized in that: an axial screw channel (111) is arranged in the cutter body (11), a counterweight (3) is slidably arranged in the screw channel (111), a power assembly (4) is coaxially arranged in the connecting pipe (21) and the connecting cap (22), the power assembly (4) comprising a micro servo motor (41), a driving shaft (42) is keyed connected to the output end of the micro servo motor (41), a disc (43) is slidably keyed connected to the driving shaft (42), a screw column (44) is slidably connected to the end of the disc (43), the screw column (44) is slidably inserted into the screw channel (111), and the screw column (44) is driven by the micro servo motor (41) to slide along the screw channel (111) to change the length of the screw channel (111). A flat part (114) is arranged on the side wall of one end of the cutter body (11), and the flat part (114) is matched with the inner wall of the connecting cap (22).

2. A numerical control cutter for valve seat machining as set forth in claim 1, characterized in that, A hollow cavity (211) is arranged in the connecting pipe (21), a recessed cavity (231) is arranged in the end head (23), the recessed cavity (231) and the hollow cavity (211) are coaxially communicated, and the micro servo motor (41) is fixed in the recessed cavity (231).

3. A numerical control cutter for valve seat machining as set forth in claim 1, characterized in that, The cross section of the screw channel (111) is rectangular, and four arc-shaped grooves are respectively matched on the four side walls of the screw channel (111).

4. A numerical control cutter for valve seat machining as set forth in claim 1, wherein The cross section of the counterweight (3) is rectangular, and the counterweight (3) comprises two rectangular end face parts (31) and four side face parts (32).

5. A numerically controlled cutter for valve seat machining as defined in claim 4, wherein A plurality of balls (33) are uniformly embedded on the side face parts (32), and the plurality of balls (33) roll on the arc-shaped grooves on the side walls of the screw channel (111).

6. A numerically controlled cutter for valve seat machining as defined in claim 5, wherein The four groups of balls (33) on the circumferential side of the counterweight (3) are respectively gap matched with the arc-shaped grooves on the corresponding side walls of the screw channel (111).

7. A numerically controlled cutter for valve seat machining as defined in claim 6, characterized in that, A buffer (34) is embedded on the end face part (31), the buffer (34) comprises a rubber column (341) and a rubber block (342), the rubber column (341) is embedded in the end face part (31), the rubber block (342) is fixed to the rubber column (341), and the rubber block (342) does not abut against the side wall of the screw channel (111).

8. A numerical control cutter for valve seat machining as set forth in claim 5, wherein One end of the disc (43) is provided with a rotating cavity (431).

9. A numerical control cutter for valve seat machining as set forth in claim 1, wherein One end of the screw column (44) is fixedly connected with a protrusion (441), and the protrusion (441) rotates in the rotating cavity (431).

10. A numerically controlled cutter for valve seat machining as defined in claim 9, wherein ​

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