Large-aperture CNC deep-hole variable-diameter boring tool and special-shaped deep-hole machining method

Abstract

The present invention discloses a large-aperture numerically controlled deep-hole variable-diameter boring tool and a method for machining special-shaped deep holes, including: a boring tool assembly located at the front end of the tool bar; a servo motor communicatively connected to a numerical control system; a transmission assembly that transmits the power output end of the servo motor to the boring tool assembly to control the radial movement of the boring tool assembly; a plurality of telescopic support assemblies arranged circumferentially on the tool bar and adapted to cooperate with the hole wall; a hydraulic unit adapted to cooperate with the telescopic support assemblies; wherein, an endoscope probe is provided at the position where the tool bar cooperates with the boring tool assembly. The present invention provides a large-aperture numerically controlled deep-hole variable-diameter boring tool and a method for machining special-shaped deep holes. By adding an endoscope hole in the tool bar of the boring tool, the machining condition can be observed in real time through the endoscope probe arranged in the endoscope hole.

Description

Technical Field

[0001] The present invention relates to the field of machining of special-shaped deep holes. More specifically, the present invention relates to a large-aperture numerically controlled deep-hole variable-diameter boring tool and the machining of special-shaped deep holes. Background Art

[0002] In the machinery manufacturing industry, generally when the ratio of the hole depth L to the hole diameter D is greater than 10 times, that is, the hole with L>10D is called a deep hole. Deep-hole machining is carried out in a closed or semi-closed state, and it is impossible to directly observe the cutting condition of the tool. Only by experience, by listening to the sound, continuously observing the shape, color of the chips and touching the tool shank and other means can the cutting condition of the tool be judged; at the same time, due to the limitation of the aperture size, the tool diameter is small, the overhang length is long, and the rigidity is poor, it is easy to generate vibration, and it is difficult to control the accuracy during the machining process due to tool deflection, the cutting conditions are relatively harsh, and it is difficult to obtain a lower surface roughness; at the same time, the chips are not easy to discharge, which is easy to block and affect the machining efficiency, and the cutting heat is not easy to dissipate, which is easy to cause the temperature of the tool and the workpiece to rise and affect the machining accuracy and tool life.

[0003] Therefore, deep-hole machining has always been regarded as a recognized technical problem in the field of metal cutting. Although in the prior art, this technical problem is solved by setting a telescopic support mechanism on the tool shank. For example, in the prior art with the patent application number 202110971698.1 and the patent name of modular boring tool, the modular boring tool uses a vulcanized body, an expansion body, a support member and a roller pair to flexibly support the boring tool during drilling operations, so that the relative rotation between the boring tool and the hole wall can be more stable and smooth. However, because the vulcanized body has elasticity and can undergo elastic deformation, in actual application, the operator adjusts the deformation direction and degree of the vulcanized body to adjust the support performance of each support member. When the vulcanized body is compressed due to the increase in the axial pressure, the vulcanized body expands radially outward, so as to provide a stronger support force to the inner wall of the accommodating cavity. When the axial pressure received by the vulcanized body weakens and stretches, the first vulcanized body contracts radially inward, thereby weakening its support force on the inner wall of the first accommodating cavity. However, the problem with it is that the support obtained through this structure is a fixed support. Although the support pressure can be adjusted to achieve flexible support, for the same support module, it cannot change with the change of the aperture, that is, variable-diameter support cannot be achieved. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0005] To achieve these objects and other advantages of the present invention, there is provided a large-aperture numerically controlled deep-hole variable-diameter boring tool, which is characterized in that it includes:

[0006] The boring tool assembly located at the front end of the tool shank;

[0007] The servo motor communicatively connected to the numerical control system;

[0008] The transmission component that transmits the power output end of the servo motor to the boring tool assembly to control the radial movement of the boring tool assembly;

[0009] A plurality of telescopic support components arranged circumferentially on the tool shank and used to cooperate with the hole wall;

[0010] The hydraulic unit that cooperates with the telescopic support component;

[0011] Wherein, an endoscope probe is provided on the tool shank at the position where it cooperates with the boring tool assembly.

[0012] Preferably, the telescopic support component is configured to include:

[0013] The T-shaped support seat embedded inside the tool shank, and an oil groove Ⅰ is provided in its extended end;

[0014] The support head sleeved on the T-shaped support seat, and a guide post that can extend into the oil groove Ⅰ is provided at its center;

[0015] The outer shell connected to the T-shaped support seat through a fixing mechanism to limit the support head;

[0016] Wherein, a predetermined gap is provided between the outer side wall of the support head and the inner side wall of the outer shell to obtain an oil groove Ⅱ, and the support head is provided with a stepped end face that is in clearance fit with the gap between the inner side wall of the outer shell in a convex manner at one end close to the support seat;

[0017] The oil groove Ⅰ and the oil groove Ⅱ are communicated with the external hydraulic unit through a hydraulic control oil circuit provided inside the tool shank.

[0018] Preferably, a bull's-eye ball is provided at the center of the top of the support head.

[0019] Preferably, a plurality of wrench holes are provided at the top of the support head.

[0020] Preferably, the outer shell is provided with threads that cooperate with the module groove on the tool shank.

[0021] Preferably, the transmission component is configured to include:

[0022] The thrust rod arranged at the axis of the tool shank and drivingly connected to the boring tool assembly through a transmission module Ⅰ;

[0023] The ball screw fixedly connected to the thrust rod, and a screw nut is threadedly connected thereto;

[0024] The transmission module Ⅱ that drivingly connects the screw nut to the power output end of the servo motor;

[0025] Wherein, bearings which cooperate with each other are arranged at both ends of the lead screw nut.

[0026] Preferably, the transmission module I is configured to include:

[0027] A rack I fixedly connected to the thrust rod;

[0028] A helical gear I and a helical gear II which are arranged side by side above the rack I through a rotating shaft and a bearing block, and the helical gear I is meshed with the rack I;

[0029] A rack II fixedly connected to the boring tool assembly;

[0030] A helical gear III which transmissionally connects the rack II and the helical gear II in space;

[0031] Wherein, a rack seat which cooperates with the corresponding rack is arranged on the tool rod, and needle roller bearings I which cooperate with the bottom surfaces of the racks are arranged on the rack seat;

[0032] Guide rail seats are arranged at positions where the tool rod is in radial moving contact with the boring tool assembly, and needle roller bearings II are arranged at positions where the guide rail seats cooperate with the side walls of the boring tool assembly.

[0033] A special-shaped deep hole machining method, which adopts a large-aperture CNC deep hole variable-diameter boring tool, includes:

[0034] S1. Based on the transmission ratio of the whole boring tool, the numerical control system drives the lead screw nut to rotate through the forward or reverse rotation of the servo motor, and then drives the thrust rod on the ball screw to axially move;

[0035] S2. When the thrust rod axially moves, it drives the boring tool to radially move through the transmission module I, and then the radial position of the boring tool changes to adjust the pre-drilled bottom hole diameter of the bored hole;

[0036] S3. After the pre-drilled bottom hole is completed, the boring tool enters the hole to the position of the first-stage step, and the switch of the hydraulic unit is turned on, so that the telescopic support assembly extends outwards under the action of hydraulic pressure and contacts the hole wall of the bottom hole to start the machining operation of the front-end hole;

[0037] S4. Replace the boring tool clamp on the boring tool assembly with a reverse boring tool clamp to machine the reverse side step and complete the machining of the special-shaped hole;

[0038] Wherein, during the machining process, the machining situation is observed in real time through an endoscope probe arranged on the boring tool assembly

[0039] Preferably, the process of the support head extending out in the telescopic support assembly is:

[0040] The hydraulic station of the hydraulic unit controls the hydraulic oil to enter the oil tank I. By increasing the amount of oil in the oil tank I, the guide column is provided with power, so that the support head integrally provided with the guide column extends outward. When the support head is extending, the hydraulic oil in the oil tank II flows back to the hydraulic station, leaving space for the support head to extend outward.

[0041] The process of retracting the support head in the telescopic support assembly is as follows:

[0042] The hydraulic station of the hydraulic unit enters oil tank II. Through the increase of oil volume in oil tank II, the hydraulic oil exerts force on the end face of the step, pressing the support head back to the initial position. When the support head is retracting, the hydraulic oil in oil tank I will flow back to the hydraulic station, leaving space for the support head to retract.

[0043] Preferably, the working process of the transmission module I is:

[0044] When the thrust rod moves axially, it drives the rack I fixedly connected to the thrust rod to move axially synchronously;

[0045] Helical gears I and II convert the axial motion of rack I into helical gear III, thereby causing rack II meshing with helical gear III to move radially.

[0046] When the rack II moves axially, it drives the boring tool assembly fixedly connected to the rack II to move radially synchronously, thereby realizing the boring tool diameter changing operation during the drilling process.

[0047] The present invention has at least the following beneficial effects:

[0048] Firstly, the present invention adds an endoscope hole in the existing boring bar, so that the processing status can be observed in real time through the endoscope, and the cutting status of the tool can be obtained.

[0049] Secondly, because the present invention cooperates with the numerical control processing method, the diameter can be changed in real time during the processing, and complex deep holes can be processed, such as a bottle-shaped cavity with small ends and a large middle.

[0050] Thirdly, the present invention sets the tool holder to be modular, and different workstation processing can be achieved by simply replacing different tool holders according to the process, which greatly reduces the time for tool changing and auxiliary operations, saves tool costs, and improves processing accuracy and production efficiency.

[0051] Fourthly, in order to solve the problems of small tool diameter, long overhang length, poor rigidity, easy vibration, and easy tool deviation during processing, the present invention arranges multiple telescopic support assemblies on the tool rod to effectively provide support for the tool and ensure its processing stability and concentricity.

[0052] Fifthly, the present invention is designed with a telescopic support assembly. After the telescopic support assembly is extended, there is a gap between the knife rod and the hole wall, and iron filings can be effectively discharged from this space.

[0053] Sixthly, the present invention designs a telescopic support component applied to a variable-diameter boring tool, which adopts a hydraulic method to control its telescopic state. Compared with the existing technology, its support range can be achieved through the adjustment of compressed oil, and the support effect is stable and can support workpieces of different heights.

[0054] Specifically, the support extension amount of the present invention changes in a follow-up manner with the change of the hole diameter of the workpiece to be processed. If the hole diameter increases, the support extends, and the amount of hydraulic oil that needs to enter will increase accordingly, and finally reach the set pressure value. Only when the pressure value remains unchanged can the stability of the support be ensured. In specific applications, the pressure value can be adjusted to a more suitable value for the current workpiece according to the actual situation such as the hardness and wall thickness of the workpiece. Generally speaking, the larger the pressure value, the greater the support force, and the greater the cutting force that can be borne. The support force can be adjusted larger or smaller according to actual application needs to achieve a better support effect.

[0055] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic structural diagram of the large-aperture CNC deep-hole variable-diameter boring tool of the present invention;

[0057] Figure 2 It is a schematic structural diagram of the tool rod section of the large-aperture CNC deep-hole variable-diameter boring tool of the present invention;

[0058] Figure 3 It is a partially enlarged schematic structural diagram of the inside of the tool rod section of the large-aperture CNC deep-hole variable-diameter boring tool of the present invention;

[0059] Figure 4 It is a partially structural schematic diagram of the position of the boring tool assembly on the tool rod section of the large-aperture CNC deep-hole variable-diameter boring tool of the present invention;

[0060] Figure 5 It is a top view structural schematic diagram of the drive module I of the present invention;

[0061] Figure 6 It is a top view structural schematic diagram of the engagement of the rack seat and the rack in the drive module I of the present invention;

[0062] Figure 7 It is a side view structural schematic diagram of the engagement of the rack seat and the rack in the drive module I of the present invention;

[0063] Figure 8 It is a bottom view connection schematic diagram of the drive module I of the present invention;

[0064] Figure 9Schematic diagram of the transmission inside the large-aperture numerically controlled deep-hole variable-diameter boring tool of the present invention;

[0065] Figure 10 Schematic diagram of a working state of the large-aperture numerically controlled deep-hole variable-diameter boring tool of the present invention;

[0066] Figure 11 Schematic diagram of the structure with an extension shank added between the tool shank and the tool holder in the large-aperture numerically controlled deep-hole variable-diameter boring tool of the present invention;

[0067] Figure 12 Schematic diagram of the structure of the inner hole in the shape of a vase in the embodiment;

[0068] Figure 13 Schematic diagram after pre-drilling the bottom hole in the embodiment;

[0069] Figure 14 Schematic diagram after machining the front-end hole in the embodiment;

[0070] Figure 15 Schematic diagram when machining the reverse step in the embodiment;

[0071] Figure 16 Schematic diagram of the cross-sectional structure of the telescopic support assembly in an embodiment of the present invention;

[0072] Figure 17 Schematic diagram of the side structure of the telescopic support assembly in an embodiment of the present invention;

[0073] Figure 18 Schematic diagram of the top view structure of the telescopic support assembly in an embodiment of the present invention;

[0074] Figure 19 Schematic diagram of the cross-sectional structure of the telescopic support assembly in an extended state in an embodiment of the present invention;

[0075] Figure 20 Schematic diagram of the side structure of the telescopic support assembly in an extended state in an embodiment of the present invention;

[0076] Figure 21 Exploded structure diagram of the telescopic support assembly;

[0077] Figure 22 Schematic diagram of the state when the telescopic support assembly switches to the extended state under the action of hydraulic oil in an embodiment of the present invention;

[0078] Figure 23 State diagram when a set of telescopic support assemblies on the tool shank are fully extended;

[0079] Figure 24In an embodiment of the present invention, the figure shows the state diagram of the telescopic support assembly when it is switched to the retracted state under the action of hydraulic oil;

[0080] Figure 25 The figure shows the state of a set of telescopic support assemblies on the tool bar after retraction. Specific embodiments

[0081] The following further describes the present invention in detail with reference to the accompanying drawings, so that those skilled in the art can implement it according to the description in the specification.

[0082] It should be understood that the terms such as "having", "including", and "comprising" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0083] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the terms is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, the terms "Ⅰ" and "Ⅱ" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0084] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, an electrical connection, a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0085] As Figure 1 shown, for machining a large-diameter and relatively shallow hole, the entire tool mainly includes a numerical control system U-axis drive servo motor 1, a transmission module Ⅱ3, a transmission module Ⅰ2, a transmission component 4, a boring tool component 5, a hydraulic unit 6, a telescopic support component 7, a tool bar 8, an endoscope 9, etc.

[0086] The servo motor 1 is connected to the numerical control system. The rotation of the servo motor 1 is controlled by the numerical control system to drive the transmission module II 2 to rotate the lead screw nut 42. The lead screw nut 42 cannot move axially. The rotation of the lead screw nut 42 pushes the ball screw 40 to move axially. The ball screw 40 is rigidly connected to the thrust rod 41, the thrust rod is rigidly connected to the rack, and the rack is precisely engaged with the gear, driving the boring tool holder 50 on the boring tool assembly 5 to move radially. The hydraulic oil pipe 7 is connected to the hydraulic station, and the telescopic support assembly 7 is controlled by the hydraulic system to support the tool rod 8. The endoscope probe 10 can observe the machining situation in real time. In the whole tool, accessories such as the boring tool assembly 5 are modularly arranged, which is convenient for replacement and assembly.

[0087] Further, when machining a deep internal hole with a large aperture similar to the shape of a bottle, the tool needs to machine along the contour, and the diameter increases from a minimum of 157 mm to 204 mm. The diameter of the workpiece changes greatly, and ordinary tools cannot meet the machining requirements. A numerically controlled variable-diameter tool is required. The depth of the internal hole of the workpiece is 2400 mm, which is equivalent to 15 times the diameter. Ordinary tools have insufficient rigidity and are prone to chatter during machining, so tool support is required.

[0088] Its working principle is generally as follows: As Figure 10 shown, when the hydraulic unit is started, the hydraulic pump sucks hydraulic oil from the fuel tank and pressurizes and outputs it. The pressurized oil flows through the oil pipe 60 to the oil tank I 71, pushing the support head 72 to extend, thereby realizing the function of supporting the tool rod 8. When the support needs to be retracted, the flow direction of the hydraulic oil is changed by controlling the reversing valve, and the pressurized oil flows through the hydraulic control oil pipe 61 inside the tool rod to the oil tank II 74 to retract the support head 72 of the hydraulic cylinder. At the same time, the pressure and flow rate of the system need to be adjusted according to the surface hardness of different workpieces to meet different support requirements and avoid damaging the inner hole surface of the workpiece.

[0089] As Figure 2 、 Figure 10 shown, the present invention is provided with a cooperating telescopic support assembly on the traditional tool, and two groups of hydraulic control oil circuits 80 are arranged on the tool rod 8 to control the free expansion and contraction of the support head 70 inside the telescopic support assembly 7, and the bull's-eye ball 76 at the top of the support head 72 is in contact with and pressed against the hole wall with a fixed pressure to resist the vibration of the tool during cutting. Specifically, as Figures 16 - 25 shown, the structure of the telescopic support assembly is configured to include:

[0090] A T-shaped support seat 70 embedded inside the tool rod 8, and an oil tank I 71 is arranged at its extended end;

[0091] A support head 72 sleeved on the T-shaped support seat, and a guide post 701 that can extend into the oil tank I 71 is arranged at its center;

[0092] The housing 73 is connected to the T-shaped support base 70 through a fixing mechanism (i.e., screw 78) to limit the support head 72. When the support head 72 extends, it is necessary to control the hydraulic oil from the hydraulic station to enter the oil groove I 71, so as to provide power for the guide column 701. The guide column 701 then controls the support head 72 to extend to the position where support is needed. At the same time, when the support head 72 extends, the hydraulic oil in the guide column 701 will flow back to the hydraulic station to leave space for the extension of the support head 72.

[0093] Wherein, there is a predetermined gap between the outer side wall of the support head 72 and the inner side wall of the housing 73 to obtain the oil groove II 74. And the support head 72 is provided with a stepped end face 75 in a convex manner at one end close to the support base 70 to form a clearance fit with the gap between the inner side walls of the housing 73. In actual application, various O-ring seals 79 are provided between the structures to ensure its sealing performance.

[0094] The oil groove I 71 and the oil groove II 74 are connected to the external hydraulic unit 6 through the hydraulic control oil circuit 80 provided inside the tool shank 8. When the support head needs to be retracted, it is necessary to control the hydraulic oil from the hydraulic station to enter the oil groove II 74. At this time, the hydraulic oil will act on the stepped end face 75 on the circumference of the support head 72, thereby controlling the retraction of the support head 72. At the same time, when the support head 72 retracts, the hydraulic oil in the oil groove II 74 will flow back to the hydraulic station to leave space for the retraction of the support head 72.

[0095] A plurality of wrench holes 77 are provided at the top of the support head 72, which are used to facilitate the cooperation with an external wrench to screw the telescopic support assembly into a predetermined installation groove.

[0096] Threads (not shown) matching the module grooves on the tool shank 8 are provided on the housing 73. When the tool needs a support mechanism during machining, only need to select a telescopic support module of the corresponding size, and then reserve a corresponding module screw-in groove on the tool according to the interface of the module. At the same time, based on the advantages of the modularization of the support mechanism, different numbers of modules can be freely selected according to the machining requirements. Multiple support holes at the same diameter can extend and retract simultaneously, which can play a good supporting role for various diameters of the inner hole of the workpiece and make the tool machining process more stable.

[0097] The function of the telescopic support assembly in this solution: The support head 72 in the telescopic support assembly 7 fits and presses against the hole wall with a fixed pressure under the action of hydraulic pressure to resist the vibration generated during tool cutting. The hydraulic unit 6 is used to ensure that there is always a constant support pressure between the hole wall and can float freely with the change of the inner hole shape. The hydraulic support is stable and has a large support force, which can effectively ensure the machining accuracy and can float freely with the change of the inner hole shape. Two groups of hydraulic support bases are arranged on the tool shank 8, and the telescopic of the support bases is controlled by the hydraulic support system.

[0098] Further, the transmission assembly is configured to include:

[0099] A thrust rod 41 disposed at the axis of the tool bar 8 and drivingly connected to the boring tool assembly 5 through a transmission module I 3;

[0100] A ball screw 40 fixedly connected to the thrust rod 41, on which a screw nut 42 is threadedly connected;

[0101] A transmission module II 2 that drivingly connects the screw nut 42 to the power output end of the servo motor 1. The machine tool numerical control system's U-axis drives the servo motor 1 to rotate forward and backward. During operation, the servo motor 1 and the transmission module II 2 drive the screw nut 42 to rotate. The transmission module II 2 includes: a synchronous pulley I 21 that mates with the power output shaft end of the servo motor 1, a synchronous belt 20, and a synchronous pulley II 22 connected to the screw nut 42. That is, when the servo motor 1 rotates forward, the synchronous belt 20 moves downward, driving the synchronous pulley 21 to rotate, and further causing the screw nut 42 connected to the synchronous pulley 21 to rotate synchronously. In this solution, the transmission module II 2 makes full use of the accurate transmission ratio of the synchronous belt 20 transmission, without slipping, to ensure the transmission accuracy, and can also adapt to a certain degree of harsh environment;

[0102] Wherein, bearings 44 are arranged at both ends of the screw nut 42 in a mating manner. In this solution, the two ends of the screw nut 42 are fixed by the bearings 44, so that the screw nut 42 only rotates without axial movement. The screw nut 42 rotates to push the ball screw 40 to move axially; the transmission of the screw nut 42 can achieve accurate linear motion and can accurately control the displacement amount. The ball screw 40 and the thrust rod 41 are rigidly connected by a connecting sleeve 45. The motion law is: the motor drives the synchronous belt to move downward, and the synchronous belt drives the thrust rod to move to the right through the screw nut 42, and vice versa to the left. The transmission ratio of the two synchronous pulleys is 1:2, that is, when the motor rotates 2 circles, the ball screw 40 moves axially by 1 pitch. The pitch of the ball screw 40 is 5 mm, that is, when the motor rotates one circle, the thrust rod moves 2.5 mm.

[0103] Further, as Figures 3 - 9 , the transmission module I 2 is configured to include:

[0104] A rack I 20 fixedly connected to the thrust rod 41. The thrust rod 41 and the rack I 20 are pin-connected by a screw 29;

[0105] A helical gear I 23 and a helical gear II 24 arranged side by side above the rack I 20 through a rotating shaft 21 and a bearing block 22, and the helical gear I 23 is in mesh with the rack I 20;

[0106] A rack II 25 fixedly connected to the boring tool assembly;

[0107] The helical gear III 26 drives the rack II 25 in a spatial transmission connection. In this solution, the rack I 20 transmits power to a single helical gear III 26 through two juxtaposed helical gears I 23 and helical gears II 24, and then the single helical gear III 26 transmits the power to the rack II 25. In this solution, the teeth of the helical gear gradually enter and exit the meshing state, so the contact ratio of the helical gear is larger than that of the spur gear, the transmission is smoother, the impact and noise are smaller, the wear of the helical gear is relatively small, the service life is longer, and it can bear a greater load, making it suitable for high-speed and heavy-load occasions. The two groups of gears have the same module and the same number of teeth, and their transmission ratio is 1:1;

[0108] Among them, a rack seat 27 that cooperates with the corresponding rack is provided on the tool bar 8, and a needle bearing I 28 that cooperates with the bottom surface of each rack is provided on the rack seat 27. The helical gear III 26 then transmits the power to the rack II 25.

[0109] The tool bar 8 is provided with a guide rail seat 81 at the position where it is in radial movement contact with the boring tool assembly 5. A needle bearing II 82 is provided at the position where the guide rail seat 81 cooperates with the side wall of the boring tool assembly 5. The helical gear III 26 meshes with the rack II 25 to drive the boring tool seat 51 to move. The four sides of the boring tool seat 51 or the tool bar 8 are installed with needle bearing guide rail seats 81 with needle bearings II 82, so that the boring tool assembly 5 and the tool bar 8 cavity are in a small clearance fit. The needle-type guide rail has the advantages of compact structure, strong load-bearing capacity, high precision, and small frictional resistance, which can make the rack seat slide on the tool bar 8 with high precision and smoothly.

[0110] In actual application, a water nozzle 52 is provided on the boring tool seat 51 to connect to the internal coolant joint in the tool handle through an internally connected water pipe 53 (i.e., the tool is an internal coolant tool). The boring tool clamp 50 is installed in the boring tool seat 51 and is pressed by two high-strength screws, with a simple structure and convenient installation.

[0111] The overall transmission ratio of the boring tool is 1:2, that is, when the motor rotates one circle, the boring tool clamp moves 2.5 mm. When the motor rotates downward, the ball screw 40 retracts, the boring tool head moves upward, and the boring hole diameter becomes smaller. Conversely, when the motor rotates upward, the ball screw 40 advances, the boring tool head moves downward, and the boring hole diameter becomes larger.

[0112] Furthermore, as Figure 11 , when machining deep holes, the tool bar needs to be extended. Therefore, the entire tool structure should include: servo motor 1, synchronous belt 20, ball screw 40, boring tool clamp 50, hydraulic oil pipe 6, support seat 7, tool bar 8, extension rod 11, tool handle 12, etc.

[0113] Example:

[0114] When machining an inner hole A similar to the shape of a vase as shown in Figure 12 , first pre-drill a bottom hole B as shown in Figure 13 ; then, asFigure 14 As shown, the boring tool is inserted into the hole to the position of the first step to prepare for machining the front-end hole. The hydraulic switch is turned on to extend the hydraulic support column to contact the hole wall, providing support and position limitation for the tool bar part to ensure the stability and concentricity of machining. The inner hole is machined according to the normal machining procedure. At the same time, since the front end of the support is a ball structure, the workpiece cannot have a stepped surface with an angle greater than 30°. The hydraulic support can provide stable and large support force, and the hydraulic pressure can be adjusted according to the surface hardness of different workpieces to ensure that the tool bar will not deflect due to force, effectively guaranteeing the machining accuracy. Moreover, the hydraulic force is stable, and the pressure can be stable at any telescopic length and can float freely with the change of the inner hole shape. Further, as Figure 15 shown, the boring tool holder 50 on the boring tool assembly 5 is replaced with a reverse boring tool holder 54, and the machining of the reverse step at B is started. Finally, the inner hole A in the shape of a vase as shown in Figure 12 is obtained.

[0115] The above solution is only an illustration of a preferred example, but is not limited thereto. When implementing the present invention, appropriate substitutions and / or modifications can be made according to the needs of users.

[0116] The number of devices and the processing scale described here are used to simplify the description of the present invention. The application, modification and variation of the present invention are obvious to those skilled in the art.

[0117] Although the embodiments of the present invention have been disclosed above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated examples described here.

Claims

1. A large-aperture numerically controlled deep-hole variable-diameter boring tool, characterized in that, Comprising: A boring tool assembly located at the front end of the tool shank; A servo motor communicatively connected to the numerical control system; A transmission assembly that transmits the power output end of the servo motor to the boring tool assembly to control the radial movement of the boring tool assembly; A plurality of telescopic support assemblies arranged circumferentially on the tool shank for cooperating with the hole wall; A hydraulic unit cooperating with the telescopic support assemblies; Wherein, an endoscope probe is provided at the position of the tool shank that cooperates with the boring tool assembly; The telescopic support assembly is configured to include: A T-shaped support seat embedded inside the tool shank, with an oil groove Ⅰ provided in its extending end; A support head sleeved on the T-shaped support seat, with a guide post that can extend into the oil groove Ⅰ provided at its center; A housing connected to the T-shaped support seat through a fixing mechanism to limit the support head; Wherein, a predetermined gap is provided between the outer side wall of the support head and the inner side wall of the housing to obtain an oil groove Ⅱ, and the support head is provided with a stepped end face that is in clearance fit with the inner side wall of the housing in a convex manner at one end close to the support seat; The oil groove Ⅰ and the oil groove Ⅱ are communicated with the external hydraulic unit through a hydraulic control oil circuit provided inside the tool shank.

2. The large-aperture numerically controlled deep-hole variable-diameter boring tool according to claim 1, wherein A bull's-eye ball is provided at the center of the top of the support head.

3. The large-aperture numerically controlled deep-hole variable-diameter boring tool according to claim 1, characterized in that, A plurality of wrench holes are provided at the top of the support head.

4. The large-aperture numerically controlled deep-hole variable-diameter boring tool according to claim 1, wherein, Threads are provided on the housing that cooperate with the module grooves on the tool shank.

5. The large-aperture numerically controlled deep-hole variable-diameter boring tool according to claim 1, wherein The transmission assembly is configured to include: A thrust rod provided at the axis of the tool shank and drivingly connected to the boring tool assembly through a transmission module Ⅰ; A ball screw fixedly connected to the thrust rod, with a screw nut threadedly connected thereto; A transmission module Ⅱ that transmits the screw nut to the power output end of the servo motor; Wherein, bearings that cooperate with each other are provided at both ends of the screw nut.

6. The large-aperture numerically controlled deep-hole variable-diameter boring tool according to claim 5, characterized in that, The transmission module Ⅰ is configured to include: A rack Ⅰ fixedly connected to the thrust rod; A helical gear Ⅰ and a helical gear Ⅱ arranged side by side above the rack Ⅰ through a rotating shaft and a bearing seat, and the helical gear Ⅰ is in meshing with the rack Ⅰ; A rack Ⅱ fixedly connected to the boring tool assembly; A helical gear Ⅲ that drivingly connects the rack Ⅱ and the helical gear Ⅱ in space; Wherein, a rack seat that cooperates with the corresponding rack is provided on the tool shank, and needle roller bearings Ⅰ that cooperate with the bottom surfaces of the respective racks are provided on the rack seat; Guide rail seats are provided at the positions where the tool shank contacts the radial movement of the boring tool assembly, and needle roller bearings Ⅱ are provided at the positions where the guide rail seats cooperate with the side walls of the boring tool assembly.

7. A method for machining special-shaped deep holes, which uses the large-aperture numerically controlled deep-hole variable-diameter boring tool described in any one of claims 1-6, and is characterized in that, Including: S1. Based on the transmission ratio of the overall boring tool, the numerical control system drives the screw nut to rotate through the forward or reverse rotation of the servo motor through the transmission module Ⅱ, and then drives the thrust rod on the ball screw to axially move; S2. When the thrust rod axially moves, it drives the boring tool to radially move through the transmission module Ⅰ, and then the radial position of the boring tool changes to adjust the diameter of the pre-drilled bottom hole of the boring hole; S3. After the pre-drilled bottom hole is completed, the boring tool enters the hole to the position of the first-stage step, and the switch of the hydraulic unit is turned on, so that the telescopic support assembly extends outward under the action of hydraulic pressure and contacts the hole wall of the bottom hole to start the machining operation of the front-end hole; S4. Replace the boring tool clamp on the boring tool assembly with a reverse boring tool clamp to machine the reverse side step and complete the machining of the special-shaped hole; Among them, during the processing, the endoscope probe set on the boring tool assembly is used to observe the processing situation in real time.

8. The special-shaped deep hole machining method according to claim 7, characterized in that, The process of the support head extending in the telescopic support assembly is as follows: The hydraulic station of the hydraulic unit controls the hydraulic oil to enter the oil tank I. By increasing the oil volume in the oil tank I, power is provided for the guide post, so that the support head integrally provided with the guide post extends outwards. When the support head is extending, the hydraulic oil in the oil tank II flows back to the hydraulic station to leave space for the extension of the support head; The process of the support head retracting in the telescopic support assembly is as follows: The hydraulic station of the hydraulic unit enters the oil tank II. By increasing the oil volume in the oil tank II, the hydraulic oil exerts a force on the stepped end face to press the support head back to the initial position. When the support head is retracting, the hydraulic oil in the oil tank I will flow back to the hydraulic station to leave space for the retraction of the support head.

9. The special-shaped deep-hole machining method according to claim 7, characterized in that, The working process of the transmission module I is as follows: When the thrust rod moves axially, it drives the rack I fixedly connected to the thrust rod to move axially synchronously; The helical gear I and the helical gear II convert and transmit the axial movement of the rack I to the helical gear III, and then make the rack II meshing with the helical gear III move radially; When the rack II moves radially, it drives the boring tool assembly fixedly connected to the rack II to move radially synchronously, realizing the boring tool diameter variation operation during the drilling process.

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