Anti-vibration cutter bar system for oversized-diameter deep hole trepanning

Abstract

The invention relates to an anti-vibration cutter bar system for oversized-diameter deep hole trepanning, belongs to the technical field of deep hole machining, and solves the problems of large machining vibration, difficulty in guaranteeing hole shape precision, abnormal wear of a cutter and the like caused by insufficient rigidity and poor guide stability of a cutter bar system during oversized-diameter deep hole trepanning machining in the prior art. The system comprises a boring rod and a modularized trepanning cutter crown, wherein the modularized trepanning cutter crown is combined with the front end of the boring rod through a transmission convex key and a screw; at least one alloy guide key and at least one piece of damping wood are arranged on the outer circle face of the modular trepanning cutter crown, and the alloy guide keys and the damping wood jointly form a composite anti-vibration guide structure. Vibration in the machining process is effectively restrained through the composite anti-vibration guide structure, the dynamic stability of a tool bar system is improved, the tool bar system is particularly suitable for trepanning machining of super-large-diameter deep holes with the diameter larger than 400 mm, the machining requirements of different inner hole diameters can be met by replacing tool crowns of different sizes, and the machining precision and efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep hole machining, in particular to an anti-vibration tool bar system for super-large diameter deep hole reaming. BACKGROUND

[0002] In the field of large energy and heavy machinery equipment manufacturing, core components (such as large rotors and pressure vessel cylinders) are usually manufactured by using integral forgings. In the machining of the inner holes thereof, reaming technology is favored because it can retain high-quality core materials. However, with the development of large-scale components, the diameter of the inner hole often needs to exceed 400 mm, or even reach more than 500 mm, which poses unprecedented challenges to the rigidity, stability and anti-vibration performance of the core components of the reaming tool bar system.

[0003] In the prior art, the tool bar for deep hole reaming generally has the following defects: first, the traditional tool bar is mostly of an integral structure or a simple modular connection, and the overall rigidity and the stability of the connection with the tool head are insufficient. When machining a super-large diameter deep hole, because the overhang is too long and the cutting torque and radial force are too large, the tool bar system is prone to severe vibration, which not only seriously affects the dimensional accuracy and surface quality of the inner hole, but also causes the connection structure to fail or even the tool to be damaged. Second, the guide part of the traditional tool bar mostly uses a single metal guide strip or damping material, which cannot simultaneously consider wear resistance and vibration absorption when dealing with super-large diameter machining, and the guiding effect is not ideal, which cannot effectively suppress the deflection and vibration. In addition, the existing tool bar system has poor universality, and a complete set of boring bar needs to be replaced for machining different hole diameters, which is costly and complicated to adjust.

[0004] Therefore, there is an urgent need in the art for a tool bar system that can improve the machining stability and quality of super-large diameter deep hole reaming. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide an anti-vibration tool bar system for super-large diameter deep hole reaming, which at least solves one of the problems of severe machining vibration, out-of-control hole shape accuracy and abnormal tool wear caused by insufficient rigidity and poor dynamic stability of the tool bar system in the prior art.

[0006] In one aspect, the embodiments of the present application provide an anti-vibration tool bar system for super-large diameter deep hole reaming, comprising a boring bar and a modular reaming cutter crown; the modular reaming cutter crown is connected with the front end of the boring bar through a transmission key and a screw; at least one alloy guide key and at least one damping wood are arranged on the outer cylindrical surface of the modular reaming cutter crown, and the alloy guide key and the damping wood together constitute a composite anti-vibration guide structure.

[0007] Further, a chip removal channel is formed in the crown body of the modular reaming cutter crown, a plurality of tool seats are assembled on the front end surface of the crown body, and a blade is detachably mounted on each tool seat.

[0008] Further, the chip removal channel is a straight groove extending axially along the crown body.

[0009] Further, the mounting surface of the shock-absorbing wood and the working surface of the alloy guide key jointly constitute a composite guide circle of the modular shell milling crown.

[0010] Further, the transmission key is matched with a key groove opened at the front end of the boring bar, and the screw is matched with a threaded hole opened at the root of the modular shell milling crown.

[0011] Further, the sum of the axial covering lengths of the alloy guide key and the shock-absorbing wood is not less than 200 mm.

[0012] Further, the diameter of the boring bar is greater than 400 mm.

[0013] Further, the modular shell milling crown adjusts the inner hole diameter of shell milling by replacing the crowns with different radial sizes.

[0014] A deep hole shell milling system comprises:

[0015] The anti-vibration tool bar system described above;

[0016] A counterweight body for being mounted on the outer circle of the pipe blank to achieve dynamic balance;

[0017] A union bolt for fastening the counterweight body;

[0018] A support ring for providing radial support under the core material in the machined hole.

[0019] In another aspect, the present application provides a deep hole shell milling method, which uses the deep hole shell milling system described above, and the method comprises the following steps:

[0020] Reference machining and dynamic balance adjustment are performed on the pipe blank;

[0021] Shell milling is performed from the first end of the pipe blank using the anti-vibration tool bar system to form an inner hole and core material, and the machining is paused after 2 / 3 of the total length of the pipe blank is machined;

[0022] At least one support ring (4) is placed under the core material in the inner hole to provide radial support for the core material;

[0023] After the pipe blank is turned over, shell milling is performed from the second end of the pipe blank until the inner hole machined from the first end is penetrated.

[0024] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0025] 1) In order to solve the problem that a single guide element in the prior art cannot simultaneously consider wear resistance and vibration absorption, the composite anti-vibration guide structure composed of an alloy guide key and a shock-absorbing wood is arranged on the outer cylindrical surface of the modular sleeve cutter crown, the high wear resistance of the alloy guide key provides rigid support, and the shock-absorbing wood absorbs and attenuates cutting vibration. The two work together to effectively suppress the chatter and deflection that easily occur in the machining of a super-large-diameter deep hole, thereby guaranteeing the size accuracy, straightness and surface quality of the hole.

[0026] 2) The standardized blade and seat that can be quickly disassembled are assembled on the front end face of the modular sleeve cutter crown, an axial straight groove type chip removal channel is arranged in the crown body, and the high-efficiency cutting and chip removal unit is formed, thereby improving the chip removal smoothness and the convenience of tool maintenance, and prolonging the service life of the tool. By replacing the cutter crown with different radial dimensions, the machining hole diameter can be flexibly adjusted, and the universality and economy of the tool bar system are significantly improved.

[0027] 3) In order to solve the problem of extreme working conditions in the machining of a super-large-diameter (greater than 500 mm) deep hole, a composite joint scheme combining a transmission key and a screw is adopted. The transmission key bears the main circumferential cutting torque to prevent relative rotation, and the uniformly distributed screws provide axial pre-tightening force to resist vibration loosening. Compared with a single connection form, the composite connection has higher connection rigidity, stronger anti-loosening ability and more reliable power transmission, thereby improving the connection stability and system service life.

[0028] 4) After single-end sleeve machining to a certain depth, a support ring is placed under the core material of the machined hole to provide intermediate radial support for the core material, thereby directly offsetting the sagging tendency caused by the self-weight. The method combines high-precision (coaxiality ≤0.2 mm) detection and adjustment at key processes (such as initial clamping and workpiece overturning), solves the problem of sleeve path deflection caused by core sagging, and ensures excellent coaxiality and straightness of the super-long deep hole.

[0029] 5) The counterweight body that can flexibly adjust the weight and position is installed on the outer circle of the pipe blank to compensate for the unbalance caused by the workpiece itself and clamping, and to realize dynamic balance during machining. The counterweight body and the support ring cooperate to reduce the machining resistance, tool load mutation and jamming risk caused by centrifugal vibration and core deflection, so that the cutting process is more stable and controllable.

[0030] 6) The machining process of segmented sleeve machining and segmented tool withdrawal is adopted. The accumulated error is controlled by shortening the single continuous machining depth, and the tool state inspection and chip cleaning can be carried out in time in the tool withdrawal gap. The method can prevent chip blockage, find and replace damaged blades or guide elements in time, avoid abnormal tool wear, edge collapse and even workpiece scrap caused by hidden faults, and improve the safety and consistency of the quality of the finished product in the machining of a super-long stroke sleeve.

[0031] In the present application, the above technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purposes and other advantages of the present application can be achieved and obtained through the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0033] Figure 1 Process flow chart of the large-diameter deep hole sleeve machining method of the present application;

[0034] Figure 2 Structure schematic diagram of the anti-vibration tool bar system assembly of the present application;

[0035] Figure 3 Structure schematic diagram of the modular sleeve tool crown of the present application; Figure 2

[0036] Figure 4 Working state schematic diagram of the support ring supporting the core material in the sleeve machining of the present application;

[0037] Figure 5 Structure schematic diagram of the counterweight of the present application;

[0038] Figure 6 Structure schematic diagram of the tool blade installation of the present application.

[0039] Reference signs:

[0040] 1, anti-vibration tool bar system assembly; 2, transmission key; 2-1, key groove; 3, screw; 3-1, threaded hole; 4, support ring; 5, boring bar; 6, modular sleeve tool crown; 7, tool holder; 8, tool blade; 9, alloy guide key; 10, shock absorbing wood; 11, chip removal channel; 12, counterweight; 13, bolt; 14, workpiece; 15, pressing plate. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application will be specifically described below in conjunction with the drawings, wherein the drawings constitute a part of this application, and are used to illustrate the principles of the embodiments of the present application, and are not used to limit the scope of the present application.

[0042] ​In the field of deep hole machining, with the increasing demand for large key components in energy, aerospace and other industries, the inner hole machining size is developing towards super large diameter (Φ500mm) and super long axial size (>8 meters). However, the existing mature BTA (jet drilling) system and other deep hole machining devices in the prior art usually stop at about Φ500mm in design and application. When the machining diameter exceeds this threshold, such as Φ500mm or even larger aperture as targeted by the present application, the overhang of the tool system increases sharply, resulting in a significant decrease in rigidity, and it is easy to produce severe vibration and let go phenomenon during machining, which seriously restricts the machining precision (such as straightness, coaxiality) and surface quality, and even leads to tool damage. To solve these problems, the present application proposes a tool bar system designed for super large diameter deep hole reaming working condition, which has excellent anti-vibration and guiding stability.

[0043] In the first aspect, one specific embodiment of the present application discloses an anti-vibration tool bar system for super large diameter deep hole reaming, as shown in Figure 2 The anti-vibration tool bar system assembly 1 core includes a boring bar 5 and a modular reaming cutter crown 6 installed at the front end of the boring bar 5.

[0044] As shown in Figure 3 The modular reaming cutter crown 6 itself is an annular structure, which is connected with the front end of the boring bar 5 through transmission keys 2 and screws 3, forming a rigidly connected whole.

[0045] Specifically, the transmission keys 2 are arranged at the front end of the boring bar 5 and cooperate with the key grooves 2-1 opened at the root of the modular reaming cutter crown 6, which are used for transmitting torque; the screws 3 pass through the root of the modular reaming cutter crown 6 and are connected with the threaded holes 3-1 on the front end surface of the boring bar 5, which are used for providing axial compression force. This structure ensures the connection rigidity and stability of the cutter crown under heavy cutting load.

[0046] On the ring body of the modular reaming cutter crown 6, complete cutting and guiding functional units are integrated: the end part is provided with a tool seat 7 for installing a blade 8; the inside of the ring body forms a chip discharge channel 11 for discharging chips; and more importantly, at least one alloy guide key 9 and at least one shock-absorbing wood 10 are arranged on the outer circular surface of the modular reaming cutter crown 6 in the circumferential and / or axial direction. The alloy guide key 9 and the shock-absorbing wood 10 are arranged adjacently or alternately, and together form a composite anti-vibration guiding structure.

[0047] When implemented, as shown in Figure 2 The anti-vibration tool bar system assembly 1 rotates and feeds under the drive of the deep hole drilling machine. The alloy guide key 9 provides macro-rigid support and geometric guidance, ensuring the straightness of the machining path; and the shock-absorbing wood 10 absorbs and attenuates cutting vibration at the micro level through its damping characteristics. The two work together in a rigid and flexible manner, and together realize the high wear resistance and high vibration resistance that a single guiding element cannot achieve.

[0048] Specifically, the anti-vibration tool bar system is driven by the deep hole drilling machine, the boring bar 5 drives the front end of the modular sleeve tool crown 6 to rotate and axially feed, and the workpiece 14 is subjected to annular cutting. In this process, the alloy guide key 9 arranged on the outer circle of the tool crown has a hardness (for example, HRC 35-55) much higher than that of the workpiece 14 material, can closely fit and slide on the machined inner hole wall surface, is a rigid support and accurate guide element, effectively resists the radial eccentric load generated by the huge cutting force, and ensures the straightness of the machining path. At the same time, the shock-absorbing wood 10 (usually engineering nylon, phenolic resin or other high polymer composite material) adjacent to or alternately arranged with the alloy guide key 9 has a certain elasticity and damping characteristics. When the tool bar system generates high-frequency micro-vibration due to cutting force fluctuation, material unevenness or long overhang, the shock-absorbing wood 10 can quickly absorb and dissipate vibration energy through contact friction with the hole wall and its own deformation, thereby inhibiting the generation and transmission of vibration.

[0049] Compared with the prior art which only uses a hard alloy guide block, the composite guide structure provided in the embodiment combines materials and functions to form a synergistic effect: the alloy guide key 9 provides geometric constraints and rigid support for the system on a macro level, ensuring the straightness of the machining path; and the shock-absorbing wood 10 improves the micro dynamic performance of the system by introducing vibration damping to absorb and dissipate vibration energy. The synergistic effect of the two enhances the overall rigidity of the tool bar system and suppresses harmful vibration in harsh working conditions of super-large diameter and super-long stroke, and ultimately improves the machining precision (such as hole straightness and coaxiality) and surface quality (avoids vibration marks) while enhancing the reliability of the machining process (reduces the risk of chipping, tool breaking and tool breaking).

[0050] Further, in combination with Figure 3 In order to ensure smooth chip discharge and avoid tool damage caused by blockage, a plurality of chip removal channels 11 are arranged in the crown body of the modular sleeve tool crown 6. The chip removal channel 11 is preferably a straight groove extending axially along the crown body, and the number of chip removal channels 11 can be set to multiple (for example, 4, 6 or 8) according to the sleeve diameter, and uniformly distributed on the circumference. Compared with spiral grooves or other complex flow channels, this straight groove design is simple in structure, smooth in flow, easy to manufacture, and has smaller resistance to large flow of chips.

[0051] Further, in order to achieve efficient and controllable annular cutting, a plurality of tool seats 7 are assembled on the front end face of the crown body of the modular sleeve tool crown 6, each tool seat 7 is provided with a positioning structure, and a blade 8 is pressed and fixed thereon by a pressing plate 15 (as shown in Figure 6 Screw 3 or other detachable means to realize reliable clamping and quick replacement of the blade. This structure is functionally coordinated with the composite anti-vibration guide structure of the present application:

[0052] During implementation, multiple inserts 8 are arranged in a ring along the end face of the cutter crown. The cutting force is balanced with the composite guide surface composed of alloy guide keys 9 and vibration-damping wood 10. The composite anti-vibration guide structure suppresses machining vibration, providing a stable working environment for the inserts 8 and improving their service life and cutting reliability, especially when machining high-hardness materials, in ultra-large diameter nesting. Simultaneously, the guiding stability ensures that the inserts 8 can work on a path closer to the theoretical trajectory, achieving precise control over the size and shape of ultra-large diameter inner holes.

[0053] Furthermore, the alloy guide key 9 is fastened to the keyway 2-1 opened on the outer circumference of the modular nesting tool crown 6 by screws 3. This connection method is firm and reliable, and easy to replace after the guide key wears out. The vibration damping wood 10 can be fixed by interference fit, adhesive, or screws 3. The mounting surface of the vibration damping wood 10 can be slightly higher than the working surface of the alloy guide key 9 in the free state, so that the vibration damping wood 10 can generate a certain amount of pre-compression after being installed in the inner hole, thereby ensuring that it always participates in guiding and vibration damping.

[0054] Furthermore, the mounting surface of the shock-absorbing wood 10 and the working surface of the alloy guide key 9 together form the composite guide outer circle of the modular nesting cutter crown 6. The diameter of this outer circle is slightly smaller than the target machining hole diameter, forming a reasonable guide clearance.

[0055] Furthermore, the transmission key 2 mates with the keyway 2-1 at the front end of the boring bar 5, primarily for transmitting torque and bearing circumferential force; the screw 3 mates with the threaded hole 3-1 at the root of the modular nesting tool crown 6, primarily for providing axial tension and eliminating gaps between the mating surfaces. This combination of key-transmitted torque and screw-3-provided clamping connection, compared to a single connection method, offers higher connection rigidity, stronger anti-loosening capability, and more reliable power transmission, making it an effective measure for achieving high-rigidity engagement of heavy-duty, large-diameter tool holders.

[0056] Furthermore, the sum of the axial coverage lengths of the alloy guide key 9 and the damping wood 10 is not less than 200 mm. Multiple sections of guide keys and damping wood 10 can be provided, distributed continuously or intermittently in the axial direction, but the total effective guide length must meet this lower limit. This guide length, significantly greater than that of conventional deep hole machining, provides sufficient straightening for ultra-long stroke machining, further suppressing radial drift of the tool holder, and is one of the key design features for ensuring hole straightness.

[0057] Furthermore, to accommodate the machining dimensions of this system, the diameter of the boring bar 5 is greater than 400mm. This matches the ultra-large diameter (>Φ500mm) nesting conditions targeted by this invention, and its structural rigidity and load-bearing capacity are unmatched by conventional small-diameter boring bars 5.

[0058] Furthermore, to enhance the versatility and economy of the tool holder system, the modular nesting cutter crown 6 adopts a customizable design. By replacing the cutter crown body with one of different radial base dimensions, or adjusting the radial extension of the insert 8 on the tool holder 7, nesting machining of different hole diameters within a certain range can be achieved. This design allows a single boring bar 5 system to adapt to various product specifications, significantly reducing equipment investment costs and tooling preparation time. Simultaneously, the slot shape of its insert 8 and the layout of its guide keys can be specifically adjusted for the material properties of different workpieces 14, thereby flexibly meeting the differentiated machining needs of key components in multiple high-end manufacturing fields such as aerospace, energy, and chemical engineering.

[0059] The alloy guide key 9 is not limited to a certain hard alloy, but can also be a cermet, cubic boron nitride (PCBN) polycrystalline material or other high hardness and high wear resistance materials.

[0060] The material of the damping wood 10 is not limited to nylon, but can also be polyurethane, modified epoxy resin board, or composite material impregnated with damping liquid, as long as it has the required vibration damping characteristics and sufficient durability.

[0061] The alloy guide key 9 (key) and the shock-absorbing wood 10 (wood) can be arranged in the circumferential direction in an alternating arrangement of one key and one wood, or in a group distribution of multiple keys and multiple woods. The specific quantity and layout can be optimized according to the vibration spectrum and stability requirements in actual processing.

[0062] The boring bar 5 can be a solid body or a hollow bar made of thick-walled seamless steel pipe. The latter can reduce the overall weight while ensuring rigidity.

[0063] The present invention also provides a deep hole sleeve machining system, including: the above-mentioned anti-vibration tool holder system, counterweight 12, clamping bolt 13 and support ring 4.

[0064] The counterweight 12 is used to be installed on the outer circle of the tube blank to achieve dynamic balance; the clamping bolt 13 is used to fasten the counterweight 12; the support ring 4 is used to provide radial support under the core material inserted into the machined hole.

[0065] A specific embodiment of the present invention also discloses a method for deep hole bushing machining. This method employs the aforementioned deep hole bushing machining system and mainly includes the following steps:

[0066] The tube blank undergoes datum machining and dynamic balancing adjustment;

[0067] The anti-vibration tool holder system is used to perform nesting machining from the first end of the tube blank to form an inner hole and core material. The machining is paused after 2 / 3 of the total length of the tube blank.

[0068] In the inner hole, at least one support ring 4 is inserted under the core material to provide radial support for the core material;

[0069] After flipping the tube blank, the tube blank is machined from the second end until it is connected to the inner hole machined from the first end.

[0070] Specifically, such as Figure 1 As shown, the method includes the following steps:

[0071] S1. Machining the alignment ring and center support ring on the outer circle of the tube blank;

[0072] S2. Mill both ends of the tube blank and machine the infeed grooves respectively;

[0073] S3. Assemble the auxiliary body and the nesting tool body on the deep hole drilling machine;

[0074] S4. Install the counterweight 12 on the outer circle of the tube blank and clamp it;

[0075] S5. Use a dial indicator to check the coaxiality of the tube blank and adjust the machine tool jaws to ensure that the coaxiality is ≤0.2mm;

[0076] S6. Perform single-end feed machining to 2 / 3 of the total length of the tube blank, and retract the tool in sections during the axial feed to check the tool and clean the chips;

[0077] S7. Insert at least three support rings 4 under the core material within the machined hole, as shown in the working state. Figure 4 As shown, radial support is provided for the core material to prevent it from sagging due to its own weight, with the deepest support ring 4 located more than 1 / 2 of the total length of the tube blank.

[0078] S8. After rechecking that the coaxiality is qualified, flip the tube blank and perform sleeve machining on the other end until it is connected to the previously machined hole;

[0079] S9. Machining threaded hole 3-1 on the end face of the core material and removing the complete core material;

[0080] S10. Finish the through-hole to the required dimensions.

[0081] The nesting process described in this method refers to the process of separating a complete cylinder (i.e., core material) with the same diameter as the target inner hole from a solid or thick-walled tube blank through circumferential cutting.

[0082] When implementing, such as Figure 1First, precise benchmark machining of the outer diameter of the tube blank (S1, S2) establishes the positioning and clamping foundation for all subsequent processes. Then, by assembling the auxiliary body and the nesting tool body (S3), hardware support is provided for efficient cutting. Before machining begins, a counterweight 12 is installed for dynamic balancing (S4), and high-precision coaxiality alignment is performed (S5), eliminating systemic vibrations caused by mass eccentricity and high-center rotation at the source. During the nesting process, this invention employs a strategy combining segmented nesting and active support: by machining one end to 2 / 3 (S6) and then switching ends for nesting (S8), the accumulation of elastic deformation caused by the long overhang of the tool is controlled; by inserting a support ring 4 under the core material (S7), the downward torque generated by the core material's own weight is actively counteracted, avoiding friction and interference between the core material and the inner wall of the tool body. These two actions work together to ensure the straightness of the deep hole. Finally, finishing (S10) ensures the dimensional accuracy and surface quality of the inner hole.

[0083] Compared with existing technologies, the solution provided in this embodiment integrates process control, dynamic stability, and structural innovation to form a complete process system:

[0084] First, dynamic balancing (S4) and high-precision coaxiality alignment (S5) eliminate macroscopic vibration sources at the system level. At the same time, the unique composite guide design on the nesting tool crown assembled in step S3 effectively suppresses cutting chatter at the micro level. Together, these three constitute a multi-layered anti-vibration system, which greatly improves the stability of the tool holder-workpiece system under high-speed rotation, thereby enabling the machined hole to have excellent straightness and coaxiality.

[0085] Secondly, the core support structure inserted in step S7 provides continuous radial support for the extra-long core material during processing, effectively preventing sagging and wobbling due to its own weight. This avoids the risks of accelerated tool wear, increased processing resistance, and even jamming. Finally, segmented nesting and end-changing machining (S6, S8) combined with forced segmented tool retraction and chip removal (S6) normalizes chip removal and tool status monitoring during processing, ensuring the continuity and safety of the process. Therefore, it improves overall processing efficiency and consistency in batch production.

[0086] Furthermore, in step S1, the number of the alignment rings is no less than 2 (e.g., 2, 3, 4, 5, or 6), located within a range of 1-1.5 meters (e.g., 1 meter, 1.1 meter, 1.2 meter, 1.3 meter, 1.4 meter, or 1.5 meter) from the end face of the tube blank, and the width is 15-40 mm (e.g., 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, or 40 mm); the number of the center frame rings is no less than 2 (e.g., 2, 3, 4, 5, or 6), and the width is 500-800 mm (e.g., 500 mm, 600 mm, 700 mm, or 800 mm).

[0087] During implementation, these rings need to be machined on a heavy-duty horizontal lathe, ensuring that the alignment ring and the center rest ring are fully polished and rounded in the circumference, i.e., machined until all surfaces are polished and have good roundness. This design enables the center rest of the deep hole drilling machine to obtain a uniform, stable, and high-precision clamping reference, laying a solid foundation for the straightness of subsequent long-stroke machining.

[0088] Furthermore, in step S2, the surface roughness of the bottom end face of the feed groove must be ≤Ra6.3 (e.g., Ra2.5, Ra3.0, Ra6.3, Ra9.0, Ra12.5, etc.) to reduce impact during cutting. The major diameter of the feed groove must be 10mm larger than the outer diameter of the tool body, and the minor diameter must be 10mm smaller than the inner diameter of the tool body. The groove depth is between 50mm and 100mm (e.g., 55mm, 60mm, 70mm, 80mm, 90mm, 100mm). This dimensional design provides sufficient guiding space for the tool crown, ensuring that it can smoothly and centrally enter the cutting state, effectively avoiding tool damage or initial path deviation caused by groove interference.

[0089] Further, in step S3, the auxiliary body and the nesting cutter body are assembled. The key component of this nesting cutter body is a modular nesting cutter crown 6, which has a tool holder 7 for mounting the cutting insert 8 and a chip removal channel 11 for chip removal. The steps of assembling the auxiliary body and the nesting cutter body include:

[0090] S31. Remove the original center frame end cover of the deep hole drilling machine;

[0091] S32. Replace with a special copper bushing that matches the machining of extra-large diameter bushings, and use screw 3 for pre-tightening and fixing;

[0092] S33. After applying lubricant to the connection between the copper sleeve and the boring bar 5, install the boring bar 5, which is specially designed for this extra-large diameter sleeve.

[0093] S34. Reassemble the center frame end cap and pre-tighten the bolts;

[0094] S35. Install the modular nesting cutter crown 6 at the front end of the boring bar 5;

[0095] S36. Conduct a tail shaft box power test.

[0096] Specifically, in step S33, lubricant should be evenly applied to the mating surfaces of the copper bushing and the boring bar 5, preferably using a high-pressure resistant special grease. In step S35, the modular bushing cutter crown 6 is fixedly connected to the mating flange at the front end of the boring bar 5 via its tail flange using high-strength bolts. All connecting bolts must be tightened twice in a diagonal sequence. In step S36, the tail shaft box power test needs to be conducted under different speeds and loads to verify the smooth operation of the entire transmission system under the torque required for ultra-large diameter bushing.

[0097] Furthermore, in step S4, the counterweight 12 includes a semi-circular counterweight ring pre-tightened to the outer circumference of the tube blank by bolts, and a counterweight plate detachably installed on the outer circumference of the counterweight ring; the dynamic balance is adjusted by increasing or decreasing the weight of the counterweight plate. The weight of the counterweight plate needs to be calculated and tested on-site based on the weight and position of asymmetrical structures (such as nozzles) on the tube blank until there is no significant vibration when the tube blank rotates. This adjustable counterweight method achieves dynamic balance correction for tube blanks with complex structures.

[0098] Furthermore, in step S6, within the first 300mm of axial feed, the tool is retracted every 100mm to check the condition of the insert 8, alloy guide key 9, and vibration damping wood 10; in subsequent machining, the tool is retracted every 500mm to clean chips and inspect the tool. This operation ensures that chips are discharged in a timely manner, avoiding chip entanglement and compression that could lead to tool breakage, scratches on the workpiece 14 surface, or even blockage of the chip removal channel 11. It also facilitates real-time monitoring of tool wear, enabling predictive replacement.

[0099] Furthermore, in step S7, the inserted support ring 4 is made of a non-metallic material with sufficient strength and that is not easily damaged by the machined hole wall, preferably nylon. The single-sided gap between the outer diameter of the support ring 4 and the inner diameter of the tube blank is controlled at 1-3 mm, preferably 2 mm (e.g., 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm), and the single-sided gap between the inner diameter of the support ring 4 and the diameter of the core material is also controlled at 1-3 mm, preferably 2 mm (e.g., 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm). This gap configuration ensures that the support ring 4 can be smoothly inserted and provides stable radial constraint for the core material.

[0100] By placing the deepest support ring 4 at a position exceeding half the length of the tube blank, it provides crucial support for the cantilever section where the core material experiences maximum deflection due to its own weight. This design uses the core material as the load-bearing body and the multiple support rings 4 as elastic fulcrums, transforming the originally prone-to-sagging cantilever beam structure into a stable continuous beam structure, thus suppressing the overall deformation and sway of the core material.

[0101] Furthermore, in step S8, the coaxiality is checked again by using a dial indicator to check the coaxiality between the outer circles at both ends and the machined inner hole, which is required to be no greater than 0.2mm (e.g., 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm).

[0102] For example, a dial indicator can be attached to the machine tool guide rail, with its probe contacting the pre-machined outer diameter reference surfaces at both ends of the tube blank and the inner wall of the formed tube. Coaxiality is assessed by detecting the radial runout of the tube blank during low-speed rotation. The runout values ​​of the four generatrices (upper, lower, left, and right) are particularly examined, and the maximum value is used as the evaluation criterion.

[0103] By evaluating the spatial consistency between the inner hole axis and the outer circle datum, a basis for controlling the uniformity of the part's wall thickness is provided. This review aims to confirm whether the geometric accuracy of the workpiece 14-machine tool system still meets the requirements after the initial nesting machining. It is a prerequisite for performing subsequent end-change machining, thereby effectively preventing error accumulation and ensuring the overall straightness of the final through hole.

[0104] Furthermore, in step S10, the finishing of the inner hole is performed by using a boring head to expand and bore, ultimately ensuring that the inner hole roughness is ≤ Ra6.3 (e.g., Ra2.5, Ra3.0, Ra4.0, Ra5.0, Ra6.0, Ra6.3, etc.).

[0105] During implementation, a dedicated precision boring head body is used to replace the lower sleeve tool body for precision boring of the through-hole. A single-edged boring bar is preferred for the finishing process, and its cutting parameters need to be adjusted according to the material of the tube blank. For example, when machining high-hardness materials such as titanium alloys and nickel-based superalloys, a relatively low cutting speed and a small feed per revolution should be used to ensure the durability of the cutting edge while obtaining good surface quality.

[0106] This finishing process corrects the microscopic shape errors left over from the nesting process and further improves the straightness of the inner hole axis. Thus, while accurately machining the inner hole dimensions to the tolerance range required by the product drawings, it ensures that the surface roughness consistently meets and exceeds the technical specification of Ra6.3, so as to meet the high standard assembly and use requirements of the final product.

[0107] Furthermore, the tube blank is a high-hardness, difficult-to-machine material, including titanium alloy or nickel-based high-temperature alloy; the modular cutting head used in the sleeve machining can be adapted to the machining requirements of different specifications of internal holes through structural adjustment.

[0108] The method of this invention is particularly suitable for difficult-to-machine materials with high hardness and high strength, such as titanium alloys and nickel-based superalloys. This invention includes dynamic balance control, segmented machining vibration reduction, forced chip removal, and a high-rigidity tool system, which can address the challenges posed by the high cutting forces, high cutting temperatures, and severe work hardening tendency of such materials. Simultaneously, the modular tool crown design allows for flexible adaptation to different internal hole machining requirements by changing different specifications of the tool crown or adjusting the radial extension of its insert 8, thereby achieving both versatility and economy in machining tools.

[0109] Furthermore, this invention also proposes a deep hole bushing machining system for performing the aforementioned method for preventing core sagging in ultra-large diameter deep hole bushing machining. The system includes:

[0110] Counterweight 12 is installed on the outer circle of the tube blank to achieve dynamic balance;

[0111] Support ring 4 is inserted under the core material inside the machined hole;

[0112] In addition, a vibration-damping tool holder system, the vibration-damping tool holder system including a boring bar 5 and a modular nesting tool crown 6, wherein an alloy guide key 9 and a shock-absorbing wood 10 are provided on the outer circular surface of the modular nesting tool crown 6.

[0113] Specifically, the counterweight 12 can compensate for the inherent mass imbalance of the tube blank and its clamping system by increasing or decreasing the number of counterweight plates or adjusting the installation position of the counterweight plates. This eliminates the centrifugal vibration of the workpiece 14 caused by poor dynamic balance, providing a stable rotational reference for subsequent high-precision nesting machining.

[0114] Specifically, the support ring 4 is an independent annular component that is inserted from the end under the core material within the machined hole after the single-end nesting has been machined to a predetermined depth. The support ring 4 maintains minute gaps between its outer diameter and the hole wall, and between its inner diameter and the core material. It is positioned under its own weight and slight external force, and its key function is to provide intermediate radial support for the gradually elongating core material. This design directly resists the sagging tendency of the core material due to its own weight, preventing risks such as nesting path deviation, uneven tool load, and core material jamming caused by sagging.

[0115] Specifically, the anti-vibration tool holder system is the core component for cutting, including the boring bar 5 and the modular nesting tool crown 6. The modular nesting tool crown 6 is connected to the front end of the boring bar 5 via a key and screw 3, forming a high-rigidity, anti-loosening engagement connection, ensuring reliable power transmission under high-torque cutting conditions. Crucially, a composite anti-vibration guiding structure, consisting of an alloy guide key 9 and a damping block 10, is provided on the outer circumference of the modular nesting tool crown 6. This structure utilizes the high wear resistance of the alloy guide key 9 to provide stable rigid support, defining the geometric accuracy of the machining path; simultaneously, the damping characteristics of the damping block 10 absorb and attenuate the mid-to-high frequency vibrations generated during cutting. The two components work together in a rigid-flexible manner, enabling the tool holder system to maintain extremely high dynamic stability even under ultra-long overhang conditions, thereby suppressing tool deflection and chatter phenomena, and ensuring the straightness, roundness, and surface quality of the machined deep holes.

[0116] In practice, the system's operation corresponds to the steps described above. First, the workpiece 14 system is dynamically balanced using counterweight 12. Next, the anti-vibration tool holder system is activated for nesting, its composite anti-vibration guiding structure providing stable guidance and vibration reduction throughout the machining process. When machining reaches a sufficient depth and the risk of core sagging becomes apparent, machining is paused and a support ring 4 is inserted to provide auxiliary support for the core material. Before flipping the workpiece 14 for docking, the dynamic balance and coaxiality must be checked again. This systematic solution, through the dynamic balance control of counterweight 12, the anti-vibration guidance of the anti-vibration tool holder, and the stabilization of the support ring 4, provides triple protection, effectively handling ultra-large diameter deep hole nesting. Ultimately, it achieves high-precision, high-reliability machining with high efficiency and complete removal of the core material.

[0117] In summary, this invention solves the technical challenges of machining deep holes with ultra-large diameters (> Φ500 mm) and ultra-long strokes (> 8 meters) through an innovative anti-vibration tool holder system and supporting processing methods. The system, with its composite anti-vibration guiding structure consisting of alloy guide keys 9 and vibration-damping wood 10, suppresses machining vibrations and improves the dynamic stability and rigidity of the tool holder system under ultra-large diameter conditions. Simultaneously, the modular tool crown design allows for flexible adaptation to machining internal holes of different specifications, enhancing the equipment's versatility and economy. At the process level, the timely intervention of the support ring 4 resists the sagging of the core material due to its own weight; combined with precise dynamic balancing adjustments and a segmented machining strategy, high coaxiality (≤ 0.2 mm) precision nesting of deep holes in ultra-long tube blanks is achieved. Ultimately, this invention, while ensuring high precision and high reliability, achieves complete core material recovery, providing a complete solution for the efficient machining of large, critical components.

[0118] The present invention will be described in more detail below through specific embodiments. These embodiments are merely descriptions of the best implementation of the invention and do not limit the scope of the invention in any way.

[0119] Example 1

[0120] Application of anti-vibration tool holder system in 34CrNi3MoV alloy steel forgings

[0121] The object to be processed in this embodiment is a solid forging of 34CrNi3MoV alloy steel with an outer diameter of Φ3000mm and a length of 10000mm. The inner diameter of the target blank is Φ500mm.

[0122] The anti-vibration tool holder system used includes:

[0123] Counterweight 12 is installed on the outer circle of the tube blank to achieve dynamic balance;

[0124] Support ring 4 is inserted under the core material inside the machined hole;

[0125] In addition, a vibration-damping tool holder system, the vibration-damping tool holder system including a boring bar 5 and a modular nesting tool crown 6, wherein an alloy guide key 9 and a shock-absorbing wood 10 are provided on the outer circular surface of the modular nesting tool crown 6.

[0126] Specifically, the boring bar 5 is a thick-walled hollow alloy steel rod with a diameter of Φ430mm. The modular nesting tool crown 6 is connected to the front end of the boring bar 5 through the flange at its root, and is rigidly engaged with the front end of the boring bar 5 by means of a transmission key 2 and eight M16 high-strength screws 3.

[0127] like Figure 3 As shown, on the outer circumferential surface of the modular nesting cutter crown 6, four sets of YG8 carbide (HRC50 hardness) alloy guide keys 9 and four sets of MC nylon vibration damping blocks 10 are arranged circumferentially, alternating evenly in a "one key, one block" configuration. The axial length of each alloy guide key 9 and vibration damping block 10 is 120mm, with a total guiding length of 960mm. On the front end face of the cutter crown, eight cutter holders 7 are evenly installed circumferentially, and each cutter holder 7 is fastened with a PCBN material cutting insert 8 by a locking bolt 13. The inner ring of the cutter crown also has a chip removal channel 11 for chip discharge.

[0128] The processing steps are as follows:

[0129] S1: Machining a 30mm wide alignment ring at each of the two end faces, 1.5 meters away; machining two 600mm wide center support rings at the middle position. All rings are machined circumferentially until they are completely smooth and round.

[0130] S2: The major diameter of the feed grooves at both ends is Φ510mm, the minor diameter is Φ380mm, the groove depth is 80mm, and the surface finish of the groove bottom is Ra2.5.

[0131] S3: Assemble the auxiliary body and the nesting tool body on the deep hole drilling machine: Remove the original center frame end cover of the deep hole drilling machine; replace it with a copper sleeve that matches the ultra-large diameter nesting machining and pre-tighten it with screw 3; apply lubricant to the connection between the copper sleeve and the boring bar 5, and then install the ultra-large diameter nesting boring bar 5; reassemble the center frame end cover and pre-tighten it with bolts; install the modular nesting tool crown 6 at the front end of the boring bar 5; finally, conduct a tail shaft box power test.

[0132] S4: Install and clamp the counterweight 12 on the outer circle of the tube blank. The counterweight 12 includes a semi-circular counterweight ring pre-tightened to the outer circle of the tube blank by bolts. Due to the good roundness of the forging, dynamic balance is achieved by installing only the counterweight ring without adding an additional counterweight plate.

[0133] S5: Use a dial indicator to check the coaxiality of the tube blank and adjust the machine tool jaws to adjust the coaxiality to 0.04mm.

[0134] S6: Perform single-end feed machining to 2 / 3 of the total length of the tube blank. During the axial feed, strictly retract the tool in segments: within the first 300mm, retract the tool once every 100mm of feed and check the tool condition; in subsequent machining, retract the tool once every 500mm of feed and clean up the chips.

[0135] S7: Insert four nylon support rings 4 with an outer diameter of Φ498mm and an inner diameter of Φ502mm into the core material inside the machined hole, with the deepest point located at a position more than 1 / 2 of the total length (i.e., more than 5000mm).

[0136] S8: After checking the coaxiality (0.4mm) again with a dial indicator and confirming it is qualified, flip the tube blank and perform sleeve machining on the other end until it is connected to the previously machined hole.

[0137] S9: Machining a threaded hole 3-1 on the end face of the core material and removing the complete core material.

[0138] S10: Finish the through-hole to the required dimensions. Use a boring head for reaming and boring, resulting in a final inner hole surface roughness of Ra2.8 and a straightness of 0.12mm / length.

[0139] Example 2

[0140] Application of anti-vibration tool holder system on INCONEL 718 tube blank with offset nozzle

[0141] The object to be processed in this embodiment is an INCONEL 718 nickel-based high-temperature alloy tube blank with an offset nozzle, with an outer diameter of Φ2000mm, a length of 11000mm, and a target inner hole of Φ500mm.

[0142] The anti-vibration tool holder system used is the same as in Example 1.

[0143] The only difference between the processing method and Example 1 is that in step S4, three counterweight plates with a total weight of 150kg are installed on the counterweight ring on the symmetrical side of the nozzle to achieve dynamic balance. In step S6, during the first 300mm of axial feed, when the tool is retracted every 100mm of feed, micro-chipping of the outer insert 8 is found. After timely replacement, the tool returns to normal.

[0144] Result: The machining was successfully completed. The final coaxiality was 0.45mm, the straightness was 0.15mm / length, the core material was removed completely without jamming, and the surface roughness of the inner hole after finishing was Ra3.0.

[0145] Example 3

[0146] The processing object is the same as in Example 1.

[0147] The anti-vibration tool holder system used has the same basic structure as in Example 1. The only difference is that the alloy guide key 9 and the shock-absorbing wood 10 on the outer circular surface of the tool crown are arranged in a "two-key, two-wood" group, with two groups symmetrically distributed.

[0148] Processing method and steps: Same as in Example 1.

[0149] Results: The processing was smoother, and the uniformity of circumferential resistance was better. The final processing effect was comparable to that of Example 1, with a final coaxiality of 0.4 mm, an inner hole straightness of 0.11 mm / length, and a surface roughness of Ra2.7.

[0150] Comparative Example 1

[0151] This comparative example uses the same workpiece 14 and anti-vibration tool holder system as Example 1, but the support ring 4 padding step (S7) is not performed. When machining to about 2 / 3 depth, a significant increase in feed resistance is felt. After continuing machining to the breakthrough point, deep marks of friction between the core material and the inner wall of the sleeve rod are found in the middle.

[0152] The results showed that the straightness of the inner hole was out of tolerance (0.55mm / total length), and the core material was partially bent, making it unusable for other purposes.

[0153] Comparative Example 2

[0154] This comparative example used the same INCONEL 718 tube blank and anti-vibration tool holder system as Example 2, but step S4 (counterweight 12 was not installed and adjusted) was not performed. After machining started, the machine tool and workpiece 14 system vibrated significantly, forcing a shutdown. Normal machining was only possible after step S4 was re-executed and dynamic balance was achieved.

[0155] Comparative Example 3

[0156] This comparative example uses the same workpiece 14 as in Example 1, but employs a conventional rigid tool holder with only a carbide guide key 9 installed, without the vibration damping wood 10.

[0157] Results: A high-frequency whistling sound was audible during the machining process, and micro-vibration marks were visible to the naked eye on the hole wall. The final inner hole roughness was only Ra5.6, and the straightness was 0.25mm / total length.

[0158] Characterization results and analysis

[0159] The characterization results of the above-described embodiments and comparative examples are shown in Table 1 below.

[0160] Table 1. Comparison of processing effects between the examples and comparative examples

[0161]

[0162] As can be seen from Table 1, in Examples 1-3 using the complete technical solution of this invention, the final coaxiality is better than 0.5 mm, the straightness is better than 0.15 mm / length, the inner hole roughness reaches Ra3.0 or better, the core material is in good condition and usable, and no jamming or vibration problems occur during processing. In contrast, Comparative Examples 1-3, due to the omission of core support, dynamic balancing correction, or replacement of the composite anti-vibration guide structure, respectively, resulted in serious deviations in coaxiality and straightness, deterioration of inner hole roughness, scrap or damage to the core material, and problems such as high feed resistance or severe vibration during processing. This demonstrates the necessity of the synergistic effect of the various technical features of this invention.

[0163] In summary, this invention solves the problem of machining deep hole sleeves with ultra-large diameters of Φ500mm and above through a complete, systematic and mutually supportive process and equipment solution, providing a reliable technical guarantee for achieving high-quality and mass production of high-end large components.

[0164] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A vibration-damping tool holder system for ultra-large diameter deep hole bushings, characterized in that, It includes a boring bar (5) and a modular nesting cutter crown (6); the modular nesting cutter crown (6) is engaged with the front end of the boring bar (5) by a transmission convex key (2) and a screw (3); at least one alloy guide key (9) and at least one shock-absorbing wood (10) are provided on the outer circular surface of the modular nesting cutter crown (6), and the alloy guide key (9) and the shock-absorbing wood (10) together constitute a composite vibration-resistant guiding structure.

2. The anti-vibration tool holder system according to claim 1, characterized in that, The modular nesting cutter crown (6) has a chip removal channel (11) inside its crown body, and a plurality of cutter holders (7) are assembled on the front end face of the crown body. Each cutter holder (7) is detachably equipped with a blade (8).

3. The anti-vibration tool holder system according to claim 2, characterized in that, The chip removal channel (11) is a straight groove extending along the axial direction of the crown.

4. The anti-vibration tool holder system according to claim 1, characterized in that, The mounting surface of the shock-absorbing wood (10) and the working surface of the alloy guide key (9) together form the composite guide outer circle of the modular nesting blade crown (6).

5. The anti-vibration tool holder system according to claim 1, characterized in that, The transmission key (2) engages with the keyway (2-1) at the front end of the boring bar (5), and the screw (3) engages with the threaded hole (3-1) at the root of the modular nesting cutter crown (6).

6. The anti-vibration tool holder system according to claim 1, characterized in that, The sum of the axial coverage lengths of the alloy guide key (9) and the shock-absorbing wood (10) is not less than 200 mm.

7. The anti-vibration tool holder system according to claim 1, characterized in that, The diameter of the boring bar (5) is greater than 400 mm.

8. The anti-vibration tool holder system according to any one of claims 1 to 8, characterized in that, The modular nesting cutter head (6) adjusts the inner diameter of the nesting process by replacing the cutter head with a cutter head that has a different radial dimension.

9. A deep hole bushing machining system, characterized in that, include: The anti-vibration tool holder system according to any one of claims 1-8; Counterweight (12) is used to be installed on the outer circle of the tube blank to achieve dynamic balance; Use bolts (13) to fasten the counterweight (12); Support ring (4) is used to provide radial support under the core material inserted into the machined hole.

10. A method for machining deep hole bushings, using the deep hole bushing system described in claim 9, characterized in that, The method includes the following steps: The tube blank undergoes reference machining and dynamic balancing adjustment; The anti-vibration tool holder system is used to perform nesting machining from the first end of the tube blank to form an inner hole and core material. The machining is paused after 2 / 3 of the total length of the tube blank. In the inner hole, at least one support ring (4) is inserted under the core material to provide radial support for the core material; After flipping the tube blank, the tube blank is machined from the second end until it is connected to the inner hole machined from the first end.

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