A lengthened boring bar connecting device based on a zero point positioning mechanism

Abstract

The application belongs to the technical field of boring machining of the inner hole of a rotary workpiece, and discloses a lengthened boring bar connecting device based on a zero-point positioning mechanism. The side surface of a power spindle box assembly is used as a connecting base surface of a boring bar seat assembly, and a lengthened boring bar assembly is clamped in the hydraulic expansion sleeve inner hole of the boring bar seat assembly, and is also connected with the power spindle tool interface in the power spindle box assembly. The boring bar seat is locked to the side surface of the power spindle box assembly through the zero-point positioning mechanism, two hydraulic expansion sleeves are arranged in the boring bar seat inner hole, and the sizes thereof correspond to the clamping outer circle diameter of the boring bar. The lengthened boring bar assemblies with the same diameter and different lengths are fastened in the boring bar seat through the hydraulic expansion sleeves, the tool shank interface flanges of the lengthened boring bar assemblies are locked to the power spindle box assembly, and the lengthened boring bar assemblies are subjected to angular and axial positioning. Meanwhile, multiple damping structures are designed in the connecting device, and the cutting vibration of the lengthened boring bar can be reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of turning and boring of the inner hole of a rotary workpiece, and relates to a lengthened boring bar connecting device based on a zero-point positioning mechanism for a turning and milling combined machine tool. BACKGROUND

[0002] The turning and milling combined machine tool can realize turning and milling boring of a workpiece in one clamping, avoids errors caused by repeated clamping of a part in different devices, and is a high-efficiency and high-precision machining method. The inner hole of some parts is very deep, and the tool for machining such an inner hole is usually more than one meter long and weighs more than 100 kilograms. Such a tool cannot be directly loaded onto a power tool spindle, and the workpiece often needs to be transferred to another special device for processing in batches, which not only prolongs the processing cycle, but also affects the processing precision due to repeated clamping. In order to expand the machining range of the machine tool and improve the processing efficiency of the part, the existing turning and milling combined machine tool uses a lengthened boring bar and the like installed on the side surface of the power tool spindle box to complete the deep hole machining of such parts. The connection between the lengthened boring bar and the power tool spindle box needs to meet the characteristics of simple and reliable structure, high clamping precision, and good damping performance. The patent with the publication number CN216441671U mentions a connection method using a dovetail groove as a locking mechanism, but there are many connection links, which has a certain influence on the connection rigidity, the clamping method of the boring bar and the boring bar seat is not clear, and the lengthened boring bar cannot be precisely positioned in the axial direction, and lacks damping measures.

[0003] Therefore, the application provides a lengthened boring bar connecting device based on a zero-point positioning mechanism, which directly connects the boring bar seat assembly to the side surface of the power tool spindle box. The lengthened boring bar assembly is also connected to the power spindle tool interface, realizing the angular and axial positioning of the boring bar. The boring bar is clamped in the boring bar seat inner hole through a hydraulic expansion sleeve, which greatly improves the clamping rigidity compared with the traditional screw tightening method. The device also designs multiple damping mechanisms, so the lengthened boring bar connecting device has good deep hole machining precision and damping performance. SUMMARY

[0004] The application provides a lengthened boring bar connecting device based on a zero-point positioning mechanism, which locks the boring bar seat to the side surface of the power spindle box through six zero-point positioning mechanisms. Two hydraulic expansion sleeves are arranged in the boring bar seat inner hole, and the size corresponds to the clamping outer diameter of the boring bar. Boring bar assemblies of the same diameter and different lengths are fastened in the boring bar seat inner hole through the hydraulic expansion sleeves, and the tool handle interface flange of the boring bar assembly is locked to the power spindle, which plays a role in angular and axial positioning of the lengthened boring bar assembly. At the same time, multiple damping structures are designed in the connecting device, which can reduce the cutting vibration of the lengthened boring bar.

[0005] The technical solution of the application is as follows:

[0006] A kind of lengthening boring bar connecting device based on zero point positioning mechanism, including power spindle box assembly 1, boring bar seat assembly 2 and lengthening boring bar assembly 3;The side of power spindle box assembly 1 is used as the connecting base surface of boring bar seat assembly 2, lengthening boring bar assembly 3 is clamped in the hydraulic expansion sleeve inner hole of boring bar seat assembly 2, simultaneously still with the power spindle tool interface 7 in power spindle box assembly 1 connection.

[0007] The side of power spindle box assembly 1 is mainly composed of the side of power spindle box 8 and auxiliary positioning block 13, the side of power spindle box 8 and auxiliary positioning block 13 are located in the same plane, multiple boring bar seat connecting zero point positioning pull nails 9 are distributed on the plane, for connecting boring bar seat assembly 2;Hydraulic quick-change connector female end 10 and cutting fluid quick-change connector female end 12 are also arranged on the side of power spindle box assembly 1, for providing hydraulic oil for boring bar seat assembly 2 and cutting fluid for lengthening boring bar assembly 3 respectively;Rubber shock-absorbing block 11 is also mounted on the side of power spindle box assembly 1, for damping after the connection of boring bar seat assembly 2;

[0008] The connecting base surface of boring bar seat assembly 2 is the side of boring bar seat 17, multiple boring bar seat connecting zero point positioning chucks 15 are installed on it, boring bar seat connecting zero point positioning chuck 15 corresponds with boring bar seat connecting zero point positioning pull nail 9 on the side of power spindle box assembly 1;Cutting fluid quick-change connector male end 14 and hydraulic quick-change connector male end 16 are also arranged on the connecting base surface of boring bar seat assembly 2, corresponding with cutting fluid quick-change connector female end 12 and hydraulic quick-change connector female end 10 on the connecting base surface of power spindle box assembly 1 respectively;Two pneumatic quick-change connector male ends 6 are installed on the opposite faces of the connecting base surface of boring bar seat assembly 2, which are communicated with boring bar seat connecting zero point positioning chuck 15 through the pipeline inside boring bar seat 17, compressed air is input into pneumatic quick-change connector male end 6, boring bar seat assembly 2 is loaded onto power spindle box assembly 1 and the connecting base surfaces of the two are closely contacted after boring bar seat connecting zero point positioning chuck 15 is opened;Then pneumatic quick-change connector male end 6 is disconnected with compressed air, boring bar seat connecting zero point positioning chuck 15 is locked with corresponding boring bar seat connecting zero point positioning pull nail 9, boring bar seat assembly 2 and power spindle box assembly 1 complete connection;At the same time, cutting fluid quick-change connector male end 14 and cutting fluid quick-change connector female end 12, hydraulic quick-change connector male end 16 and hydraulic quick-change connector female end 10 are connected respectively as cutting fluid quick-change connector and hydraulic quick-change connector, hydraulic oil and cutting fluid are transported from power spindle box assembly 1 to boring bar seat assembly 2 through cutting fluid quick-change connector and hydraulic quick-change connector, for the next locking of lengthening boring bar assembly 3 and the center water outlet of lengthening boring bar 27;

[0009] The interior of the boring bar seat 17 is equipped with a front hydraulic expansion sleeve 21 and a rear hydraulic expansion sleeve 18, which are installed on the front end face and the rear end face of the boring bar seat 17 respectively, and the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18 form two hydraulic oil chambers with the inner hole of the boring bar seat 17 through a star-shaped sealing ring 20, and the two hydraulic oil chambers are communicated with the male end 16 of the hydraulic quick-change connector through the pipeline inside the boring bar seat 17; the inner cooling end cover 25 is installed at the rear end of the boring bar seat 17, and the inner cooling end cover 25 is provided with a spring vibrator damping mechanism, and the cutting vibration of the lengthened boring bar assembly 3 is absorbed through the resonance of the spring vibrator damping mechanism; the inner cooling end cover 25 is also provided with a center water outlet quick-change connector male end 26, which is communicated with the cutting fluid quick-change connector male end 14 through the internal pipeline of the boring bar seat assembly 2; the other side surface parallel to the connecting base surface of the boring bar seat assembly 2 is provided with a boring bar seat storage zero point positioning pull nail 5 and a pneumatic quick-change connector male end 6, the boring bar seat storage zero point positioning pull nail 5 provides a positioning reference for the automatic exchange of the boring bar seat assembly 2, and the pneumatic quick-change connector male end 6 is used for connecting the boring bar seat connection zero point positioning chuck 15 to open compressed air.

[0010] The lengthened boring bar assembly 3 mainly comprises a lengthened boring bar 27 with an internal damping unit, a boring bar mounting plate 33 and a tool holder interface flange plate 34; the lengthened boring bar 27 is fastened to the boring bar mounting plate 33 through a gland 29 and a locking expansion sleeve 30; two O-rings 32 are installed at the cooperation position between the boring bar mounting plate 33 and the outer circle of the lengthened boring bar 27, hydraulic oil film 31 is filled between the two O-rings 32, a sealing ring 37 is installed on a piston 36, the piston 36 moves in the oil chamber of the boring bar mounting plate 33 and seals the hydraulic oil film 31, and a pressure regulating screw 35 is screwed in the boring bar mounting plate 33 and contacts with the piston 36; the pressure of the hydraulic oil film 31 is adjusted by the piston 36 pressed by the pressure regulating screw 35, and the cutting vibration transmitted by the tool tip of the lengthened boring bar 27 is further attenuated through the two groups of O-rings 32 and the high-pressure hydraulic oil film 31 after passing through the internal damping unit at the front end thereof; the boring bar mounting plate 33 is provided with the tool holder interface flange plate 34 at the other end; a center water outlet quick-change connector female end 28 is installed at the rear end of the lengthened boring bar 27 and cooperates with the center water outlet quick-change connector male end 26 in the inner cooling end cover 25; the boring bar mounting plate 33 is also provided with two lengthened boring bar storage zero point positioning pull nails 4, which provide a positioning reference for the automatic exchange of the lengthened boring bar assembly 3.

[0011] The boring bar seat 17 is also provided with a rubber damping seat 19 on the side surface, which is closely matched with the rubber damping block 11 after the power spindle box assembly 1 is connected with the boring bar seat assembly 2, thereby increasing the shear damping of the connecting base surface and reducing the cutting vibration of the lengthened boring bar assembly 3.

[0012] The pipeline inside the boring bar seat 17 is also provided with a pressure measuring connector 38 for pressure detection of the hydraulic oil chamber and air discharge.

[0013] The spring oscillator damping mechanism is mainly composed of a tensile spring 22, bolts 23 and a spring oscillator 24.

[0014] When the lengthened boring bar assembly 3 is connected, first, the boring bar seat assembly 2 is connected with the power spindle box assembly 1; then the power spindle box assembly 1 is in a loose tool state, and then the lengthened boring bar 27 is moved along the axis of the lengthened boring bar 27 to the lengthened boring bar assembly 3, so that the rear end of the lengthened boring bar 27 enters the inner holes of the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18, the tool shank interface flange plate 34 is combined with the power spindle tool interface 7 on the power spindle box assembly 1, then the power spindle box assembly 1 is in a draw tool state, and the tool shank interface flange plate 34 is locked on the power spindle tool interface 7; finally, hydraulic oil is supplied to the hydraulic oil chambers of the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18 through the connected hydraulic quick-change connector female end 10 and the hydraulic quick-change connector male end 16, so that the thin-walled inner holes of the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18 are deformed, the clamping connection of the cylindrical tool shank at the rear end of the lengthened boring bar 27 is completed, and the high-precision connection of the lengthened boring bar assembly 3 through the front hydraulic expansion sleeve 21, the rear hydraulic expansion sleeve 18 and the power spindle tool interface 7 is completed. After the connection of the lengthened boring bar assembly 3 is completed, the center water outlet quick-change connector female end 28 at the rear end of the lengthened boring bar 27 is also connected with the center water outlet quick-change connector male end 26 at the rear end of the boring bar seat assembly 3, and cutting fluid can enter the inner cooling end cover 25 through the connected cutting fluid quick-change connector female end 12 and cutting fluid quick-change connector male end 14, and then enter the lengthened boring bar 27 through the center water outlet quick-change connector male end 26 and the center water outlet quick-change connector female end 28, and finally reach the cutting area of the tool tip.

[0015] The beneficial effects of the present application are:

[0016] 1. The high-rigidity locking of the standard cylindrical tool shank lengthened boring bar is realized, the lengthened boring bar with different length-diameter ratios can be adapted through the boring bar seat assembly, and the lengthened boring bar with a non-standard interface does not need to be customized. Meanwhile, the hydraulic expansion sleeve in the boring bar seat assembly realizes extremely high locking rigidity on the outer diameter of the boring bar.

[0017] 2. A high-precision connection base surface based on a zero-point positioning mechanism is invented. The zero-point positioning draw pin is installed on the side surface of the power spindle box body by fully utilizing the structural characteristics, the installation base surface is maximally expanded, the connection rigidity and precision are reliably ensured, the air path of the zero-point positioning chuck is introduced from the boring bar seat through the quick-change connector, the complex pipeline in the power spindle box body is avoided, and the structural feasibility for automatic exchange of the lengthened boring bar is provided.

[0018] 3. The invention of a variety of damping mechanism suitable for lengthening boring bar, including the pre-tightening damping between the two O-rings at the front end and the boring bar cylindrical surface and the damping of vibration energy by hydraulic oil film; two high-damping damping rubber seats further attenuate the vibration through structural internal damping; two ring-type hydraulic locking expansion sleeves directly absorb the vibration of the boring bar body; and the spring vibrator damping mechanism at the last end of the boring bar seat assembly, which absorbs the cutting vibration transmitted by the boring bar through resonance. Through these structural inventions, the cutting capacity of the lengthened boring bar assembly has been essentially improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of the connection of the lengthened boring bar.

[0020] Figure 2 is a layout diagram of the connection base surface of the power spindle box assembly.

[0021] Figure 3 is a layout diagram of the connection base surface of the boring bar seat assembly.

[0022] Figure 4 is Figure 3 A-A cross-sectional view of

[0023] Figure 5 is Figure 4 B-B cross-sectional view of

[0024] Figure 6 is Figure 4 C-C cross-sectional view of

[0025] In the figure: 1 power spindle box assembly; 2 boring bar seat assembly; 3 lengthened boring bar assembly; 4 lengthened boring bar storage zero point positioning pull pin; 5 boring bar seat storage zero point positioning pull pin; 6 male end of pneumatic quick-change connector; 7 power spindle tool interface; 8 power spindle box; 9 boring bar seat connection zero point positioning pull pin; 10 female end of hydraulic quick-change connector; 11 rubber damping block; 12 female end of cutting fluid quick-change connector; 13 auxiliary positioning block; 14 male end of cutting fluid quick-change connector; 15 boring bar seat connection zero point positioning chuck; 16 male end of hydraulic quick-change connector; 17 boring bar seat; 18 rear hydraulic expansion sleeve; 19 rubber damping seat; 20 star-shaped sealing ring; 21 front hydraulic expansion sleeve; 22 tension spring; 23 bolt; 24 spring vibrator; 25 internal cooling end cover; 26 male end of center water outlet quick-change connector; 27 lengthened boring bar; 28 female end of center water outlet quick-change connector; 29 gland; 30 locking expansion sleeve; 31 hydraulic oil film; 32 O-ring; 33 boring bar mounting plate; 34 tool shank interface flange; 35 pressure regulating screw; 36 piston; 37 sealing ring; 38 pressure measuring connector. DETAILED DESCRIPTION

[0026] The specific embodiments of the invention are further illustrated below in combination with the drawings and technical solutions.

[0027] The application discloses a lengthened boring bar connecting device based on a zero-point positioning mechanism, which comprises a connecting base surface based on a zero-point positioning mechanism, a clamping mechanism adopting a hydraulic expansion sleeve and a tool holder interface flange plate locked by a power spindle; the side surface of a power spindle box assembly 1 is used as the connecting base surface of a boring bar seat assembly 2, and a lengthened boring bar assembly 3 is clamped in the hydraulic expansion sleeve inner hole of the boring bar seat assembly 2 and is connected with a power spindle tool interface 7 in the power spindle box assembly 1.

[0028] The side surface of the power spindle box assembly 1 is mainly composed of the side surface of the power spindle box 8 and an auxiliary positioning block 13, and the side surface of the power spindle box 8 and the auxiliary positioning block 13 are located on the same plane, a plurality of boring bar seat connecting zero-point positioning pull nails 9 are distributed on the plane and are used for connecting the boring bar seat assembly 2; a hydraulic quick-change connector female end 10 and a cutting fluid quick-change connector female end 12 are arranged on the side surface of the power spindle box assembly 1 and are respectively used for providing hydraulic oil for the boring bar seat assembly 2 and providing cutting fluid for the lengthened boring bar assembly 3; a rubber damping block 11 is further arranged on the side surface of the power spindle box assembly 1 and is used for damping after the boring bar seat assembly 2 is connected.

[0029] The connecting base surface of the boring bar seat assembly 2 is arranged on the side surface of a boring bar seat 17, a plurality of boring bar seat connecting zero-point positioning chucks 15 are mounted on the connecting base surface and correspond to the boring bar seat connecting zero-point positioning pull nails 9 on the side surface of the power spindle box assembly 1; the connecting base surface of the boring bar seat 17 is further provided with a cutting fluid quick-change connector male end 14 and a hydraulic quick-change connector male end 16, which correspond to the cutting fluid quick-change connector female end 12 and the hydraulic quick-change connector female end 10 on the connecting base surface of the power spindle box assembly 1 respectively; two pneumatic quick-change connector male ends 6 are mounted on the opposite surfaces of the connecting base surface of the boring bar seat assembly 2, which are communicated with the boring bar seat connecting zero-point positioning chucks 15 through the pipelines in the boring bar seat 17, compressed air is input into the pneumatic quick-change connector male ends 6, the boring bar seat assembly 2 is loaded onto the power spindle box assembly 1 and the connecting base surfaces of the two are closely contacted after the boring bar seat connecting zero-point positioning chucks 15 are opened; then the compressed air connected with the pneumatic quick-change connector male ends 6 is disconnected, the boring bar seat connecting zero-point positioning chucks 15 are locked with the corresponding boring bar seat connecting zero-point positioning pull nails 9, and the boring bar seat assembly 2 is connected with the power spindle box assembly 1; at the same time, the cutting fluid quick-change connector male end 14 and the cutting fluid quick-change connector female end 12 and the hydraulic quick-change connector male end 16 and the hydraulic quick-change connector female end 10 are respectively connected to form a cutting fluid quick-change connector and a hydraulic quick-change connector, and the hydraulic oil and the cutting fluid are transported from the power spindle box assembly 1 to the boring bar seat assembly 2 through the cutting fluid quick-change connector and the hydraulic quick-change connector, and are used for locking the lengthened boring bar assembly 3 and center water outlet of the lengthened boring bar 27 in the next step; the side surface of the boring bar seat 17 is further provided with a rubber damping seat 19, which is closely matched with the rubber damping block 11 after the power spindle box assembly 1 is connected with the boring bar seat assembly 2, thereby increasing the shear damping of the connecting base surface and reducing the cutting vibration of the lengthened boring bar assembly 3.

[0030] The inside of the boring bar seat 17 is equipped with a front hydraulic expansion sleeve 21 and a rear hydraulic expansion sleeve 18, which are installed on the front end face and the rear end face of the boring bar seat 17 respectively. The front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18 form two hydraulic oil chambers with the inner hole of the boring bar seat 17 through a star-shaped sealing ring 20. The two hydraulic oil chambers are communicated with the male end 16 of the hydraulic quick connector through the pipeline inside the boring bar seat 17. A pressure measuring connector 38 is also installed on the pipeline inside the boring bar seat 17 for pressure detection and air discharge of the hydraulic oil chamber. An inner cooling end cover 25 is installed at the rear end of the boring bar seat 17. The inner cooling end cover 25 is provided with a spring vibrator damping mechanism. The spring vibrator damping mechanism is mainly composed of a tension spring 22, a bolt 23 and a spring vibrator 24. Four bolts 23 are evenly distributed and installed on the inner hole end face of the inner cooling end cover 25. One end of the four tension springs 22 is hung on the bolt 23, and the other end is hung on the spring vibrator 24. The cutting vibration of the lengthened boring bar assembly 3 is absorbed through the resonance of the spring vibrator 24. The inner cooling end cover 25 is also equipped with a center water outlet quick connector male end 26, which is communicated with the cutting fluid quick connector male end 14 through the internal pipeline of the boring bar seat assembly 2. The other side face parallel to the connecting base face of the boring bar seat assembly 2 is equipped with a boring bar seat storage zero point positioning pull nail 5 and a pneumatic quick connector male end 6. The boring bar seat storage zero point positioning pull nail 5 provides a positioning reference for the automatic exchange of the boring bar seat assembly 2. The pneumatic quick connector male end 6 is used to connect the compressed air of the boring bar seat connection zero point positioning chuck 15.

[0031] The lengthened boring bar assembly 3 is mainly composed of a lengthened boring bar 27 with an internal damping unit, a boring bar mounting plate 33 and a tool holder interface flange plate 34. The lengthened boring bar 27 is fastened to the boring bar mounting plate 33 through a gland 29 and a locking expansion sleeve 30. Two O-rings 32 are installed at the cooperation position between the boring bar mounting plate 33 and the outer circle of the lengthened boring bar 27. Hydraulic oil film 31 is filled between the two O-rings 32. A sealing ring 37 is installed on the piston 36. The piston 36 moves in the oil chamber of the boring bar mounting plate 33 and seals the hydraulic oil film 31. The pressure of the hydraulic oil film 31 is adjusted by the piston 36 which is in contact with the piston 36 through the threaded tightening of the pressure regulating screw 35 in the boring bar mounting plate 33. The cutting vibration transmitted by the tool tip of the lengthened boring bar 27 is further attenuated through the two groups of O-rings 32 and high-pressure hydraulic oil film 31 after passing through the internal damping unit at the front end of the lengthened boring bar 27. The tool holder interface flange plate 34 is installed at the other end of the boring bar mounting plate 33. A center water outlet quick connector female end 28 is installed at the rear end of the lengthened boring bar 27, which cooperates with the center water outlet quick connector male end 26 in the inner cooling end cover 25. Two lengthened boring bar storage zero point positioning pull nails 4 are also installed on the boring bar mounting plate 33. The lengthened boring bar storage zero point positioning pull nail 4 provides a positioning reference for the automatic exchange of the lengthened boring bar assembly 3.

[0032] When the lengthened boring bar assembly 3 is connected, first, the boring bar seat assembly 2 is connected with the power spindle box assembly 1; then the power spindle box assembly 1 is in the loose tool state, and then the lengthened boring bar 27 is moved along the axis of the lengthened boring bar 27 to the lengthened boring bar assembly 3, so that the rear end of the lengthened boring bar 27 enters the inner hole of the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18, the tool shank interface flange plate 34 is combined with the power spindle tool interface 7 on the power spindle box assembly 1, then the power spindle box assembly 1 is in the draw tool state, and the tool shank interface flange plate 34 is locked on the power spindle tool interface 7; finally, the hydraulic oil is supplied to the hydraulic oil cavity of the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18 through the connected hydraulic quick-change connector female end 10 and the hydraulic quick-change connector male end 16, so that the thin-walled inner hole of the front hydraulic expansion sleeve 21 and the rear hydraulic expansion sleeve 18 is deformed, the clamping connection of the cylindrical tool shank at the rear end of the lengthened boring bar 27 is completed, and the high-precision connection of the lengthened boring bar assembly 3 through the front hydraulic expansion sleeve 21, the rear hydraulic expansion sleeve 18 and the power spindle tool interface 7 is completed. After the connection of the lengthened boring bar assembly 3 is completed, the center water outlet quick-change connector female end 28 at the rear end of the lengthened boring bar 27 is also connected with the center water outlet quick-change connector male end 26 at the rear end of the boring bar seat assembly 2, and the cutting fluid can enter the inner cooling cover 25 through the connected cutting fluid quick-change connector female end 12 and the cutting fluid quick-change connector male end 14, and then enter the lengthened boring bar 27 through the center water outlet quick-change connector male end 26 and the center water outlet quick-change connector female end 28, and then directly reaches the tool tip cutting area.

Claims

1. A lengthened boring bar connection device based on a zero point positioning mechanism, characterized in that, The lengthened boring bar connecting device comprises a power spindle box assembly (1), a boring bar seat assembly (2) and a lengthened boring bar assembly (3); the side of the power spindle box assembly (1) is used as the connecting base surface of the boring bar seat assembly (2), the lengthened boring bar assembly (3) is clamped in the hydraulic expansion sleeve inner hole of the boring bar seat assembly (2), and is connected with the power spindle tool interface (7) in the power spindle box assembly (1) at the same time; wherein The side of the power spindle box assembly (1) is mainly composed of the side of the power spindle box (8) and the auxiliary positioning block (13), the side of the power spindle box (8) and the auxiliary positioning block (13) are located on the same plane, a plurality of boring bar seat connecting zero point positioning pull nails (9) are distributed on the plane, and the boring bar seat assembly (2) is connected; the hydraulic quick change connector female end (10) and the cutting fluid quick change connector female end (12) are arranged on the side of the power spindle box assembly (1), and are used for providing hydraulic oil for the boring bar seat assembly (2) and cutting fluid for the lengthened boring bar assembly (3) respectively; the rubber damping block (11) is also mounted on the side of the power spindle box assembly (1), and is used for damping after the boring bar seat assembly (2) is connected; The connecting base surface of the boring bar seat assembly (2) is the side of the boring bar seat (17), a plurality of boring bar seat connecting zero point positioning chucks (15) are mounted on the side of the boring bar seat (17), the boring bar seat connecting zero point positioning chucks (15) correspond to the boring bar seat connecting zero point positioning pull nails (9) on the side of the power spindle box assembly (1); the cutting fluid quick change connector male end (14) and the hydraulic quick change connector male end (16) are arranged on the connecting base surface of the boring bar seat assembly (2), and correspond to the cutting fluid quick change connector female end (12) and the hydraulic quick change connector female end (10) on the connecting base surface of the power spindle box assembly (1) respectively; the two pneumatic quick change connector male ends (6) are mounted on the opposite surfaces of the connecting base surface of the boring bar seat assembly (2), the pneumatic quick change connector male ends (6) are communicated with the boring bar seat connecting zero point positioning chucks (15) through the pipeline in the boring bar seat (17), compressed air is input into the pneumatic quick change connector male ends (6), the boring bar seat connecting zero point positioning chucks (15) are opened after the boring bar seat assembly (2) is loaded onto the power spindle box assembly (1) and the connecting base surfaces of the two are closely contacted; then the compressed air of the pneumatic quick change connector male ends (6) is disconnected, the boring bar seat connecting zero point positioning chucks (15) are locked with the corresponding boring bar seat connecting zero point positioning pull nails (9), and the boring bar seat assembly (2) and the power spindle box assembly (1) are connected; at the same time, the cutting fluid quick change connector male end (14) and the cutting fluid quick change connector female end (12), and the hydraulic quick change connector male end (16) and the hydraulic quick change connector female end (10) are connected respectively to form the cutting fluid quick change connector and the hydraulic quick change connector, and the hydraulic oil and the cutting fluid are delivered from the power spindle box assembly (1) to the boring bar seat assembly (2) through the cutting fluid quick change connector and the hydraulic quick change connector, and are used for the locking of the lengthened boring bar assembly (3) and the center water outlet of the lengthened boring bar (27) in the next step. The inside of the boring bar seat (17) is equipped with front hydraulic expansion sleeve (21) and rear hydraulic expansion sleeve (18), which are installed on the front end face and rear end face of the boring bar seat (17) respectively, the front hydraulic expansion sleeve (21) and the rear hydraulic expansion sleeve (18) form two hydraulic oil chambers with the inner hole of the boring bar seat (17) through the star-shaped sealing ring (20), the two hydraulic oil chambers are communicated with the male end of the hydraulic quick connector (16) through the pipeline inside the boring bar seat (17); The inner cooling end cover (25) is installed at the rear end of the boring bar seat (17), the inner cooling end cover (25) is provided with a spring oscillator damping mechanism, the cutting vibration of the lengthened boring bar assembly (3) is absorbed through the resonance of the spring oscillator damping mechanism; The inner cooling end cover (25) is also equipped with a center water outlet quick connector male end (26), which is communicated with the cutting fluid quick connector male end (14) through the internal pipeline of the boring bar seat assembly (2); The other side surface parallel to the connecting base surface of the boring bar seat assembly (2) is equipped with a boring bar seat storage zero point positioning pull nail (5) and a pneumatic quick connector male end (6), the boring bar seat storage zero point positioning pull nail (5) provides a positioning reference for the automatic exchange of the boring bar seat assembly (2), and the pneumatic quick connector male end (6) is used for connecting the boring bar seat connection zero point positioning chuck (15) to open compressed air.

2. The lengthened boring bar connecting device based on the zero point positioning mechanism according to claim 1, wherein The lengthened boring bar assembly (3) is mainly composed of a lengthened boring bar (27) with an internal damping unit, a boring bar mounting plate (33) and a tool holder interface flange (34); the lengthened boring bar (27) is fastened to the boring bar mounting plate (33) through a gland (29) and a locking expansion sleeve (30); two O-rings (32) are installed at the cooperation position between the boring bar mounting plate (33) and the outer circle of the lengthened boring bar (27), hydraulic oil film (31) is filled between the two O-rings (32), a piston (36) is equipped with a sealing ring (37), the piston (36) moves in the oil chamber of the boring bar mounting plate (33) and seals the hydraulic oil film (31), and a pressure regulating screw (35) is screwed in the boring bar mounting plate (33) and contacts the piston (36); the pressure of the hydraulic oil film (31) is adjusted by the piston (36) pressed by the pressure regulating screw (35), and the cutting vibration transmitted by the tool tip of the lengthened boring bar (27) is further attenuated after passing through the internal damping unit at the front end thereof and then passing through the two groups of O-rings (32) and the high-pressure hydraulic oil film (31); the boring bar mounting plate (33) is installed with the tool holder interface flange (34) at the other end; a center water outlet quick connector female end (28) is installed at the rear end of the lengthened boring bar (27) and cooperates with the center water outlet quick connector male end (26) in the inner cooling end cover (25); the boring bar mounting plate (33) is also equipped with two lengthened boring bar storage zero point positioning pull nails (4), which provide a positioning reference for the automatic exchange of the lengthened boring bar assembly (3).

3. The lengthened boring bar connecting device based on the zero point positioning mechanism according to claim 2, wherein The side of the boring bar seat (17) is also provided with a rubber damping seat (19), which is tightly matched with the rubber damping block (11) after the power spindle box assembly (1) is connected with the boring bar seat assembly (2), thereby increasing the shear damping of the connecting surface and reducing the cutting vibration of the lengthened boring bar assembly (3).

4. The lengthened boring bar connecting device based on the zero-point positioning mechanism according to claim 3, characterized in that, The boring bar seat (17) is also provided with a pressure measuring connector (38) on the pipeline inside the boring bar seat (17), which is used for pressure detection and air discharge of the hydraulic oil cavity.

5. The lengthened boring bar connecting device based on the zero-point positioning mechanism according to claim 4, characterized in that, The spring oscillator damping mechanism is mainly composed of a tensile spring (22), a bolt (23) and a spring oscillator (24), four bolts (23) are evenly distributed and installed on the inner hole end face of the inner cooling end cover (25), and four tensile springs (22) are hung on the bolt (23) at one end and hung on the spring oscillator (24) at the other end.

6. The lengthened boring bar connecting device based on the zero-point positioning mechanism according to claim 5, characterized in that, When the lengthened boring bar assembly (3) is connected, first, the boring bar seat assembly (2) is connected with the power spindle box assembly (1); then the power spindle box assembly (1) is in the loose tool state, then the lengthened boring bar (27) is moved along the axis of the lengthened boring bar (27) to the lengthened boring bar assembly (3), so that the rear end of the lengthened boring bar (27) enters the inner hole of the front hydraulic expansion sleeve (21) and the rear hydraulic expansion sleeve (18), the tool handle interface flange plate (34) is combined with the power spindle tool interface (7) on the power spindle box assembly (1), then the power spindle box assembly (1) is in the tool pulling state, and the tool handle interface flange plate (34) is locked on the power spindle tool interface (7); finally, the hydraulic oil is supplied to the hydraulic oil cavity of the front hydraulic expansion sleeve (21) and the rear hydraulic expansion sleeve (18) through the connected hydraulic quick connector female end (10) and the hydraulic quick connector male end (16), so that the thin-walled inner hole of the front hydraulic expansion sleeve (21) and the rear hydraulic expansion sleeve (18) is deformed, the cylindrical tool handle at the rear end of the lengthened boring bar (27) is clamped and connected, and the high-precision connection of the lengthened boring bar assembly (3) is completed through the front hydraulic expansion sleeve (21), the rear hydraulic expansion sleeve (18) and the power spindle tool interface (7); after the connection of the lengthened boring bar assembly (3) is completed, the center water outlet quick connector female end (28) at the rear end of the lengthened boring bar (27) is also connected with the center water outlet quick connector male end (26) at the rear end of the boring bar seat assembly (2), and the cutting fluid enters the inner cooling end cover (25) through the connected cutting fluid quick connector female end (12) and cutting fluid quick connector male end (14), and then enters the lengthened boring bar (27) through the center water outlet quick connector male end (26) and the center water outlet quick connector female end (28) to reach the tool tip cutting area.

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