Boring cutter bar with built-in detachable damping mechanism and assembly method of boring cutter bar

Abstract

The invention relates to a boring cutter bar with a built-in detachable damping mechanism and an assembling method thereof.The boring cutter bar comprises a cutter bar body, the cutter bar body comprises a working section, a vibration reduction section and a clamping section, one end of the vibration reduction section is connected with the working section, the other end of the vibration reduction section is connected with the clamping section, the vibration reduction section comprises the damping mechanism, and the clamping section is connected with the clamping section. The damping mechanism comprises a damping cavity, a first spring and a second spring, wherein the damping cavity extends in the axis direction of the cutter bar body; the restraining ring is arranged in the damping cavity; the vibration reduction block is arranged in the restraint ring in a sliding and penetrating mode, a first axial gap is formed in the end, close to the working section, of the vibration reduction block, and a second axial gap is formed in the end, close to the clamping section, of the vibration reduction block. According to the boring cutter bar with the built-in detachable damping mechanism, perfect unification of super-strong rigid fixation of the damping unit and lossless and convenient maintenance is achieved in engineering, and the core contradiction in the prior art is fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of precision boring, and more specifically, to a boring bar with a built-in detachable damping mechanism and its assembly method. Background Technology

[0002] In the field of precision boring, especially under harsh conditions such as deep hole drilling, large overhang, and intermittent cutting, the decrease in machining accuracy, deterioration of surface quality, and shortened tool life caused by tool holder chatter are long-standing core problems. To reduce tool holder chatter and improve stability, creating a cavity inside the boring bar and inserting a damping device has become an effective and mainstream technical approach. This technology dissipates vibration energy through the damping unit, improving the stability of the machining process. Specifically, current technologies typically employ "semi-permanent fixation" or "removable" solutions to enhance stability.

[0003] "Semi-permanent fixation" refers to permanently welding or fastening a high-density alloy damping weight to an internal shaft, while other buffer components (such as filling fluid and vibration damping components) can be replaced. This method sacrifices maintainability and adaptability, mainly leading to the following two problems: First, users cannot quickly change damping units of different specifications according to different machining tasks (for example, rough boring requires a large mass block to resist strong impacts, while finish boring requires optimized dynamic balance to suppress high-frequency micro-vibrations), resulting in poor tool process adaptability. Second, once the non-removable damping unit suffers internal damage or performance degradation due to long-term vibration and impact, or if the user's process requirements change permanently, the entire expensive tool holder faces functional obsolescence, resulting in resource waste.

[0004] The "detachable" solution, where the high-density alloy damping counterweight is replaceable, solves the maintenance problem, but suffers from insufficient connection rigidity and reliability, easily introducing secondary vibrations and having a limited lifespan. For example, Chinese patent document CN222660162U describes a damping boring bar for deep hole machining on a lathe. This bar uses a combination of snap-fit ​​and threaded connection mechanisms. The connection interface has flexibility and gaps, preventing the inertial force of the damping unit from being fully and efficiently transferred to the bar body. A significant amount of vibration energy is lost at the connection interface, severely weakening the vibration reduction effect. In continuous high-frequency vibration environments, threaded connections inherently risk loosening, while snap-fit ​​structures are prone to wear gaps after repeated disassembly and reassembly. This connection method cannot provide continuous, stable, high-rigidity constraints, causing the damping unit to potentially experience minute relative movements within the cavity. This not only reduces vibration reduction efficiency but also allows the damping unit itself to become a new source of vibration and noise due to collisions and fretting wear.

[0005] In summary, it is difficult to achieve both "rigid and reliable fixation" and "convenient and non-destructive disassembly" for the damping unit within the tool holder cavity. Summary of the Invention

[0006] To address the problem in existing technologies where it is difficult to achieve both "rigid and reliable fixing" and "convenient and non-destructive disassembly" of the damping unit, an innovative boring bar structure is provided.

[0007] This invention reveals that using high-performance materials such as tungsten carbide and high-density alloys as damping bodies or constraint components is a clear trend in pursuit of ultimate vibration reduction effects. However, these materials differ significantly from the tool holder body (usually steel) in physical properties, especially in their coefficients of thermal expansion. Existing technologies lack optimized assembly methods for combining high-performance dissimilar materials. The currently used traditional interference fit method, when assembling dissimilar materials, easily generates excessive circumferential tensile stress within brittle cemented carbide or high-density alloy components due to differences in shrinkage after cooling, leading to cracking. If threaded connections are used, it is difficult to guarantee extremely high coaxiality and connection rigidity, and the same problems of stress concentration and loosening exist. The inability to provide a connection method that can accommodate huge thermal expansion differences, achieve ultra-rigid locking, and allow for non-destructive disassembly constitutes a key technical bottleneck in the development of high-performance, maintainable vibration-damping tools.

[0008] The boring bar provided by this invention, featuring a built-in detachable damping mechanism based on thermal expansion difference locking, simultaneously satisfies the requirements of "rigid and reliable fixation" and "convenient and non-destructive disassembly." On one hand, it ensures that the damping unit is subjected to a continuous and stable radial locking force far exceeding that of traditional mechanical methods while in operation within the boring bar cavity, achieving "zero-backlash" rigid fixation during operation and obtaining optimal vibration reduction performance. On the other hand, this locking force can be completely released through a simple and non-destructive operation, thereby enabling rapid replacement, maintenance, or reconstruction of the damping unit according to process requirements. Furthermore, this structure can perfectly adapt to and utilize high-performance materials such as tungsten carbide and high-density alloys, which have a significant difference in thermal expansion coefficient compared to steel.

[0009] The specific plan is as follows: A boring bar with a built-in detachable damping mechanism includes a tool bar body, which comprises a working section, a damping section, and a clamping section. One end of the damping section is connected to the working section, and the other end is connected to the clamping section. The damping section includes a damping mechanism comprising: a damping cavity extending along the axial direction of the tool bar body; a constraint ring disposed in the damping cavity; and a damping block slidably passing through the constraint ring. The damping block has a first axial clearance at its end near the working section and a second axial clearance at its end near the clamping section.

[0010] Preferably, the outer diameter of the working section is smaller than the outer diameter of the damping section.

[0011] Preferably, the working section is a solid structure and is not connected to the damping cavity, thereby providing stable support for the cutting tip.

[0012] Preferably, the end or side of the working section is machined with a precision structure for connecting the cutting unit.

[0013] Preferably, the clamping section is a solid cylinder. The outer surface of the clamping section may be machined with a standard tool holder taper (such as BT, HSK) or a straight shank for clamping. This structure provides a rigid connection to the machine tool spindle, and the entire section is solid to ensure maximum torsional and bending stiffness to transmit cutting torque and axial force.

[0014] Preferably, a first partition structure is provided between the shock-absorbing section and the working section, and a second partition structure is provided between the shock-absorbing section and the clamping section.

[0015] Preferably, the first partition structure includes a first stepped transition section and a first solid partition.

[0016] Preferably, the second partition structure includes a second stepped transition section and a second solid partition.

[0017] Preferably, the outer surface of the constraint ring is interference-fitted with the inner wall of the damping cavity, and the interference amount of the interference fit is 0.01-0.03 mm.

[0018] Preferably, the contact surface between the constraint ring and the damping cavity is coated with a high-strength, high-temperature resistant epoxy structural adhesive.

[0019] This invention provides a solution for coating the contact surface with a high-strength, high-temperature resistant epoxy structural adhesive, incorporating chemical bonding before the constraint ring is press-fitted into the assembly. After press-fitting, the adhesive cures, forming a dual bond of mechanical interference and chemical adhesion, making the constraint ring and the tool holder body a permanently connected whole.

[0020] Preferably, the damping block is designed to match the inner diameter of the constraint ring, and its length is significantly greater than that of the constraint ring. More preferably, the length of the damping block is more than twice the length of the constraint ring. This design originates from the core mechanism of the "tuned mass damper" in vibration control theory, ensuring sufficient mass with sufficient length.

[0021] Preferably, the damping cavity is a blind hole.

[0022] In some embodiments, the damping cavity is formed by machining a precise cylindrical blind hole from its front end to its rear end using a deep-hole drilling process (such as gun drilling). This process ensures that the cavity has high straightness, roundness, and surface finish. The bottom of the damping cavity is a solid closed structure. The axial thickness of the solid partition (i.e., the second partition structure) between the solid bottom and the clamping section is greater than or equal to the diameter of the damping cavity. This design is used to withstand the torque from the working section and prevent the tool holder from torsional deformation or breakage at the root.

[0023] Preferably, the constraint ring includes: an inner ring, which is slidably disposed with the vibration damping block; and an outer ring, which is disposed circumferentially with the inner ring, and the outer ring and the inner ring are manufactured by a heat-fitting process.

[0024] Preferably, the constraint ring is installed at a distance of approximately 0.6 to 0.75 times the overhang length of the tool holder from the clamping section. In this invention, this position corresponds to the region with a large amplitude of the first-order bending mode of the tool holder, and applying rigid constraints at this location can most effectively change the dynamic stiffness of the system.

[0025] Preferably, the inner ring and the outer ring are coaxial and of equal length.

[0026] Preferably, the coefficient of thermal expansion of the outer ring is greater than that of the inner ring. More preferably, the coefficient of thermal expansion of the outer ring is 3 × 10⁻⁶ greater than that of the inner ring material. -6 / °C or above.

[0027] Preferably, the inner ring is made of tungsten carbide cemented carbide or low-expansion iron-nickel alloy. Its inner diameter is precision ground to form a machined cylindrical surface, which serves as the locking surface. Its outer diameter is the assembly reference surface.

[0028] Preferably, the outer ring is made of alloy steel or stainless steel.

[0029] More preferably, the inner ring is made of YG8 cemented carbide, and the outer ring is made of 40Cr alloy steel.

[0030] Preferably, the mass of the damping block is 5 to 8 times the mass of the inner ring.

[0031] The secondary vibration system, formed by locking the inner ring of the constraint ring with the damping block, has an inertial effect that determines its ability to dissipate the vibration energy of the primary system. The specific limitation on the length of the damping block is intended to ensure that it has a minimum inertial mass for effective operation.

[0032] Preferably, a heating interface is provided circumferentially on the outer ring. The heating interface is provided for ease of operation, to guide hot air or enhance the heat sensation to increase heating efficiency.

[0033] More preferably, the heating interface is selected from an annular groove. The configuration of the annular groove provides a clear spatial guide and positioning reference for the application of external heat sources, making operation more convenient and significantly improving the concentration and efficiency of heating through different implementation methods.

[0034] In some implementations, the annular groove directly serves as a heat concentration area, allowing the operator to precisely target and heat the groove area using an external heat source such as a high-temperature hot air gun, raising the outer ring temperature to the target temperature.

[0035] In some embodiments, the annular groove serves as the physical space for accommodating a non-contact induction heating coil. When disassembly is required, the induction coil is placed within or around the groove, and a high-frequency alternating current is applied. The alternating magnetic field generated by the coil induces eddy currents in the outer ring body, which is made of a magnetically conductive material (e.g., 40Cr alloy steel). This causes the outer ring to heat up and expand rapidly and uniformly due to the Joule effect, thereby relieving its radial clamping force on the inner ring.

[0036] In other embodiments, a magnetic ring made of a high-permeability material is circumferentially embedded within the annular groove, preferably made of silicon steel sheet (electrical steel). This magnetic ring is firmly fixed to the groove by an interference fit or a high-temperature structural adhesive with a temperature resistance exceeding 300°C to ensure it does not loosen during repeated thermal cycling. In this configuration, when the external induction coil operates, the magnetic ring, due to its high permeability, highly concentrates the magnetic lines of force of the alternating magnetic field, thereby inducing eddy currents within itself that are much stronger than those in the outer ring body. These eddy currents are efficiently converted into Joule heat, causing the temperature of the magnetic ring to rise rapidly in a very short time. It then acts as a highly efficient built-in heat source, rapidly and concentratedly transferring heat to the outer ring body in close contact with it via thermal conduction, achieving precise and rapid heating of the target area of ​​the outer ring, greatly improving the response speed and energy efficiency of the thermal actuation process.

[0037] Preferably, both the first axial clearance and the second axial clearance are 0.05-0.4 mm, and more preferably, the first axial clearance and the second axial clearance are set to be equal.

[0038] After the damping block is installed into the constraint ring, it is placed inside the damping cavity. Its length is less than the depth of the damping cavity, ensuring axial clearance between its two ends and the front and rear end faces of the cavity after installation. These clearances accommodate manufacturing tolerances, thermal expansion, and ensure the locking force is purely radial. Its cylindrical surface is constrained only along a localized length where it mates with the inner ring of the constraint ring; for the majority of its length, the cylindrical surface does not contact the cavity wall, maintaining a radial clearance between the cylindrical surface and the cavity wall, allowing it to function as a free, inertial mass.

[0039] Preferably, the damping block is a cylinder, and the cylinder is selected from a solid cylinder, a sealed metal capsule, or a bimetallic composite cylinder.

[0040] Preferably, the cylinder is a solid cylinder made of a high-density alloy material.

[0041] More preferably, the high-density tungsten-based alloy has a density ρ ≥ 17.0 g / cm³. 3 The preferred series is W-Ni-Fe.

[0042] More preferably, the high-density tungsten-based alloy is WNiFe-90 (90-6-4) or WNiFe-93 (93-4.2-2.8).

[0043] The density of WNiFe-90 (90-6-4) is ≥17.0 g / cm³. 3 It meets the requirements and has the best plasticity and machinability in the series. This means that it can be relatively easily precision machined into cylinders of Φ16.000×120mm and has good resistance to microcracks under long-term vibration loads, with the highest reliability.

[0044] WNiFe-93 (93-4.2-2.8) has a higher density (approximately 17.8%), which can directly increase the inertial mass by about 4% without changing the design dimensions, potentially leading to further improvements in vibration reduction performance.

[0045] In contrast, it is not recommended to choose grades with WNiFe-95 or higher tungsten content, because although they have extremely high density, they are brittle and are at risk of internal damage or even breakage under impact or high-frequency vibration, which is not conducive to the long-term durability of vibration damping components.

[0046] Preferably, the outer diameter of the damping block D_damper = Φ16.000 mm, and the length of the damping block L_damper = 120 mm.

[0047] In some embodiments, the cylinder is a sealed metal capsule containing a particulate damping agent (such as tungsten carbide powder) or a high-viscosity damping fluid. End caps are designed at both ends of the outer shell, and the overall shape remains cylindrical.

[0048] Preferably, the cylinder is a bimetallic composite cylinder, which is formed by rolling or stacking two metal strips with different coefficients of thermal expansion. More preferably, the two metal strips with different coefficients of thermal expansion are an Invar alloy strip and a copper strip.

[0049] The "bimetallic composite cylinder" of the present invention generates cyclic alternating stress inside the composite due to different expansion amounts under cutting temperature rise. Energy is dissipated through internal friction of the material, providing additional thermo-mechanical coupling damping.

[0050] Another aspect of the present invention provides an assembly method, comprising the following steps: (1) The constraint ring is semi-permanently fixed to the inner wall of the middle end of the damping cavity; (2) Insert the damping block into the opening of the damping cavity, slide it through the constraint ring, and push it to the bottom of the cavity; The semi-permanent fixation is selected from one of interference fit, interference fit and chemical bonding.

[0051] Preferably, the constraint ring includes an inner ring and an outer ring, the outer ring of the constraint ring is semi-permanently fixed to the inner wall of the middle end of the damping cavity, and the damping block is slidably inserted in the inner ring of the constraint ring, wherein the expansion coefficient of the outer ring is greater than the expansion coefficient of the inner ring.

[0052] The "thermal expansion difference locking" described in this invention, also known as "intelligent locking," refers to a process that achieves automatic locking by utilizing the properties of materials through heating and cooling. Specifically, in this invention, it mainly refers to the installation process of the constraint ring: Locked State: At room temperature, the compressive stress of the outer ring puts the inner ring under pressure. According to the thick-walled cylinder theory, this pressure causes the inner hole of the inner ring to shrink and deform. Under design conditions, the actual diameter of the inner hole of the inner ring is less than the outer diameter of the damper. The difference (outer diameter of the damper - actual diameter of the inner hole) is the working radial interference, which is usually between 0.005mm and 0.015mm. The resulting contact pressure is the locking force.

[0053] Release State: When disassembly is required, an external heat source (such as a hot air gun) is used to locally heat only the outer ring. The outer ring temperature rises until its inner diameter increases, causing a significant reduction in the radial compressive stress applied to the inner ring, even to zero or tensile stress. Under elastic recovery, the inner ring's inner diameter expands. Through design, it is ensured that the expanded inner diameter is greater than the outer diameter of the vibration damping device, forming a disassembly radial clearance δ_r (typically >0.005mm). At this point, the interference fit between the vibration damping device and the inner hole disappears, allowing axial movement.

[0054] The dimensional chain design equation must satisfy the following condition: the actual diameter of the inner ring's inner hole < the outer diameter of the damper block < the enlarged inner hole diameter. This is achieved by accurately calculating the difference in thermal expansion between the two materials at the temperatures of the locked and released states, combined with the initial thermal fit interference, part geometry, and material elastic modulus.

[0055] The "thermal fitting process" described in this invention involves uniformly heating the outer ring to a temperature of high thermal expansion (e.g., the 40Cr alloy used in one embodiment of this invention can be heated to 280°C-320°C), causing the inner diameter of the outer ring to expand to a temperature greater than the room-temperature outer diameter of the inner ring. Simultaneously, the inner ring can be cooled or kept at room temperature. Then, the inner ring is quickly inserted into the inner hole of the outer ring. After the entire ring cools to room temperature, the outer ring contracts, generating a large and continuous radial compressive stress σ_r on the outer surface of the inner ring. This compressive stress puts the inner ring in a pre-compression state.

[0056] The beneficial effects are as follows: 1. This invention, through its unique constraint ring structure, namely the "thermally actuated intelligent constraint ring," achieves for the first time in engineering the perfect unity of "ultra-rigid fixing of the damping unit" and "non-destructive and convenient maintenance," fundamentally solving the core contradiction of existing technologies. Utilizing the thermodynamic properties of two materials with different coefficients of thermal expansion: at room temperature (operating state), the high-expansion outer ring cools and contracts, generating a huge and continuous radial compressive stress on the low-expansion inner ring. This compressive stress forces the inner ring's inner hole to elastically contract, thereby applying an active radial clamping force to the damping block far exceeding that of traditional transition fits or thread preload. This clamping force does not attenuate due to vibration during operation, achieving "zero-gap" rigid coupling and completely eliminating the risk of fretting wear and secondary vibration of the damping block within the cavity. When maintenance is required, only a conventional heat source (such as a hot air gun) is needed to locally heat the outer ring. The outer ring expands upon heating, rapidly reducing or eliminating the compressive stress applied to the inner ring. The inner ring's inner hole returns to its original shape under elastic action, the clamping force is instantly and completely released, and the damping block can be removed without damage. This intelligent mechanism of "cooling self-locking and heating self-releasing" enables high-performance damping units to be reliably fixed and quickly replaced like standard modules for the first time, solving the long-standing technical problem that has plagued the industry: "fixed but not replaceable, replaceable but not securely fixed".

[0057] (2) This invention significantly improves the overall dynamic performance and machining quality of the boring system by combining "ultra-rigid fixing of the damping unit" with "dynamic position optimization". Through the aforementioned ultra-rigid clamping, this invention ensures a near-integral mechanical connection between the damping mass block and the tool holder body, allowing the inertial force of the damping mass block to react on the tool holder with almost no loss, greatly improving the effective dynamic stiffness of the tool holder system. Furthermore, this invention explicitly designs the installation position of the damping unit (i.e., the constraint ring position) in the critical area of ​​tool holder vibration (e.g., 0.6-0.75 times the overhang from the clamping end), rather than placing it arbitrarily. Applying high-quality rigid constraints at this optimal position can most effectively change and optimize the natural frequency and mode shape of the tool holder structure, concentrating vibration energy on a path that can be efficiently consumed. The synergistic effect of these two aspects enables the tool holder of this invention to work stably within a wider range of cutting speeds and depths of cut, significantly suppressing chatter, thereby achieving higher surface finish, dimensional accuracy, and extending tool life.

[0058] (3) This invention adapts to and unlocks the application of high-performance dissimilar material combinations in maintainable vibration-damping cutting tools, breaking through existing material and process bottlenecks. To pursue extreme performance, the use of high-density tungsten alloys, tungsten carbide, etc., as damping or constraint components is a clear trend, but these materials have vastly different coefficients of thermal expansion compared to steel tool holders. The conventional room-temperature interference fit used in existing technologies, when assembling dissimilar materials, easily generates fatal circumferential tensile stress within the brittle cemented carbide or high-density alloy due to inconsistent shrinkage after cooling, leading to cracking (e.g., attempting to directly press a tungsten carbide ring into a steel tool holder). This invention creatively transforms this difference in thermal expansion coefficients into the core driving force for achieving functionality. First, a high-expansion steel outer ring and a low-expansion tungsten carbide inner ring are pre-combined into a constraint ring assembly using a controllable "thermal fitting" process. This process utilizes the controlled thermal expansion difference for assembly, ensuring controllable stress. Subsequently, this assembly is permanently fixed to the tool holder. Ultimately, functional locking and releasing rely entirely on the controlled expansion and contraction of the outer ring between the "operating temperature" and the "disassembly temperature." This mechanism completely avoids the traditional problem of directly applying dangerous assembly stresses to brittle materials, paving the way for the safe and reliable use of optimal material combinations in detachable structures and unlocking the enormous potential for improving vibration damping performance through material upgrades.

[0059] (4) This invention endows the boring bar with unprecedented reconfigurability and life-cycle economy, expanding its application scope and reducing overall costs. This invention makes the damping unit a field-replaceable functional module. It can be replaced according to different machining conditions: for example, in rough boring, it can be replaced with a large mass tungsten alloy block to obtain high impact resistance; in fine boring, it can be replaced with a damping block or particle damping unit with optimized dynamic balance to suppress high-frequency micro-vibrations; the damping characteristics can also be adjusted for different workpiece materials. This realizes on-demand programming and rapid reconfiguration of the performance of a single tool bar, greatly expanding its process adaptability. From an economic point of view, in traditional integrated design, the damage to any component of the expensive damping unit or tool bar body may lead to the scrapping of the entire unit. However, the modular design of this invention means that only the relatively low-cost damping module can be regarded as a consumable and replaced, while the expensive tool bar body and precision constraint ring assembly can be reused for a long time. This not only reduces the long-term use cost for users, but also reduces resource waste and reflects the advanced green manufacturing concept.

[0060] (5) The overall structural design of this invention is simple, and the manufacturing process it relies on is mature, ensuring the high reliability of the product and the feasibility of mass production. Although the function is intelligent, the "thermally actuated intelligent constraint ring" of this invention is composed of only two concentric ring parts combined through a standard thermal fitting process. The structure is extremely simple and symmetrical, with no complex moving parts. The deep hole drilling (machining blind holes), precision grinding (machining ring parts), interference fit and high-strength adhesive bonding (fixing constraint rings) used in the tool holder body are all highly mature and reliable standardized processes in the field of mechanical manufacturing. This integrated innovation based on mature processes minimizes the production difficulty and quality control risks, ensures the consistency, stability and long-term reliability of product performance, and lays a solid foundation for large-scale industrial production and market promotion. Attached Figure Description

[0061] Figure 1 This is the front view of the present invention; Figure 2 This is a left view of Embodiment 1 of the present invention; Figure 3 for Figure 1 AA view; Figure 4 for Figure 3 BB view; Figure 5 A schematic diagram of a working section with a precision structure; Figure 6 for Figure 5 AA view; Figure 7 for Figure 5 BB view; Figure 8This is a schematic diagram of the first-order bending vibration mode and constraint effect of the boring bar; Figure 9 This is a schematic diagram of the structure of Embodiment 4 of the present invention; Figure 10 This is a schematic diagram of the structure of Embodiment 5 of the present invention.

[0062] Explanation of the labels in the diagram: 1. Tool holder body; 11. Working section; 12. Vibration damping section; 13. Clamping section; 14. First solid partition; 15. Second solid partition; 16. First stepped transition section; 17. Second stepped transition section; 18. Conical part; 19. Flange; 2. Damping cavity; 21. First axial clearance; 22. Second axial clearance; 3. Vibration damping block; 4. Constraint ring; 41. Inner ring; 42. Outer ring; 421. Annular groove; 3'. Metal capsule; 31. Capsule shell; 321. First end cap; 322. Second end cap; 33. Damping medium; 3''. Bimetallic composite cylinder; 34. First metal strip layer; 35. Second metal strip layer. Detailed Implementation

[0063] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0064] Example 1: Boring tool bar with built-in detachable damping mechanism Please see Figures 1 to 7 The boring bar with a built-in detachable damping mechanism according to an embodiment of the present invention includes a tool bar body 1, which includes a working section 11, a damping section 12, and a clamping section 13. One end of the damping section 12 is connected to the working section 11, and the other end of the damping section 12 is connected to the clamping section 13. The damping section includes a damping mechanism, which includes: a damping cavity 2 extending along the axial direction of the tool bar body 1; a constraint ring 4 disposed in the damping cavity 2; and a damping block 3 slidably passing through the constraint ring 4. The end of the damping block 3 near the working section 11 has a first axial clearance 21, and the end of the damping block 3 near the clamping section 13 has a second axial clearance 22.

[0065] In this embodiment, the tool holder body is made of high-strength 42CrMo alloy steel bar and manufactured by an integral molding process.

[0066] In this embodiment, the outer diameter of the working section 11 is smaller than the outer diameter of the damping section 12. The working section 11 is a solid structure and is not connected to the damping cavity 2, thereby providing stable support for the blade tip.

[0067] Furthermore, the end or side of the working section 11 is machined with a precision structure 111 for connecting the cutting unit.

[0068] The clamping section 13 is a solid cylinder, and its outer surface can be machined with a standard tool holder taper (such as BT, HSK) or a straight shank for clamping.

[0069] A first partition structure is provided between the working section 11 and the vibration damping section 12, and a second partition structure is provided between the clamping section 13 and the vibration damping section 12. The first partition structure includes a first stepped transition section 16 and a first solid partition 14, and the second partition structure includes a second stepped transition section 17 and a second solid partition 15.

[0070] In other implementation schemes, only the first or second partition structure can be selected. The purpose of the partition structure is to increase the rigidity of the structure and improve the stability of the overall structure. In this embodiment, the best effect is achieved by having two partition structures, each of which contains a stepped transition section and a solid partition. However, the design can be reduced or changed according to the requirements.

[0071] The first axial gap 21 and the second axial gap 22 are both 0.05-0.4 mm. In this embodiment, the first axial gap 21 and the second axial gap 22 are both 0.2 mm.

[0072] The outer surface of the constraint ring is interference-fitted with the inner wall of the damping cavity, and the interference amount of the interference fit is 0.01-0.03 mm.

[0073] In this embodiment, the damping block 3 is a solid cylinder made of tungsten-nickel-iron high-density alloy material. The outer diameter D_damper = Φ16.000 mm and the length L_damper = 120 mm of the damping block 3.

[0074] Furthermore, the constraint ring 4 includes: an inner ring 41, which is slidably disposed with respect to the damping block; and an outer ring 42, which is disposed circumferentially with respect to the inner ring, and the outer ring and the inner ring are manufactured by a heat-fitting process.

[0075] The inner ring 41 is made of YG8 cemented carbide, and the outer ring 42 is made of 40Cr alloy steel.

[0076] Preferably, the mass of the damping block is 5 to 8 times the mass of the inner ring.

[0077] The secondary vibration system, formed by locking the inner ring of the constraint ring with the damping block, has an inertial effect that determines its ability to dissipate the vibration energy of the primary system. The specific limitation on the length of the damping block is intended to ensure that it has a minimum inertial mass for effective operation.

[0078] The lower limit of this length and its corresponding mass ratio were determined through precise physical calculations of the key components in this embodiment. The inner ring of the constraint ring is made of YG8 cemented carbide (density approximately 14.5 g / cm³). 3 The dimensions are Φ15.985 / Φ23.000×20 mm, and its calculated mass is approximately 62.3 grams. The damping block is made of a high-density tungsten-nickel-iron alloy (density ≥17.5 g / cm³). 3 The damping block has a diameter of Φ16.000 mm and a calculated linear density of approximately 3.519 g / mm². Calculations show that when the damping block length is twice the inner ring length (i.e., 40 mm), its mass is approximately 140.8 g, with a mass ratio to the inner ring of approximately 2.3:1. Considering manufacturing tolerances and to provide a reliable margin to ensure basic performance, the lower limit of the mass ratio is set at 3 times (corresponding to a mass of approximately 190 g), serving as the design starting point for the secondary system to generate significant inertial effects and achieve measurable damping performance.

[0079] In some preferred embodiments, the mass of the damping block is designed to be 5 to 8 times the mass of the inner ring. This range provides a clear target range for high-performance design. Its lower limit (5 times, approximately 310 grams) ensures that the damping performance significantly exceeds the basic threshold; its upper limit (8 times, approximately 500 grams) is strictly limited by the theoretical maximum mass (approximately 424 grams) corresponding to the physical depth of the damping cavity (120.4 mm), and serves as a reference for the theoretical performance boundary. In the current embodiment, the damping block, with a length of 120 mm and a mass of approximately 422.4 grams, has a mass-to-weight ratio of approximately 6.8. This design value, under given spatial constraints, increases the inertial mass to near the theoretical limit (space utilization exceeding 99.6%), thereby achieving optimal inertial configuration within a limited space, representing the optimal solution for balancing ultimate performance and engineering feasibility.

[0080] The fundamental purpose of determining this core mass ratio range is to quantify the inertia parameters to ensure the damping block possesses sufficient momentum. When the tool holder vibrates, the secondary system with the high mass ratio generates significant inertial hysteresis, thereby inducing strong relative motion and damping dissipation at the interface formed with the inner ring, ultimately achieving efficient suppression of flutter. This "5 to 8 times" range also reserves forward-looking design space for further performance improvements through materials or fine-tuning the structure.

[0081] Furthermore, the outer ring 42 is provided with an annular groove 421 in the circumferential direction.

[0082] The annular groove provides a clear spatial guide and positioning reference for the application of external heat sources, making operation more convenient and significantly improving the concentration and efficiency of heating through different implementation methods.

[0083] The annular groove can be directly used as a heat concentration area. The operator can use an external heat source such as a high-temperature hot air gun to accurately target the groove area for local heating, so that the outer ring temperature rises to the target temperature.

[0084] Alternatively, the annular groove can serve as the physical space to accommodate the non-contact induction heating coil. When disassembly is required, the induction coil is placed within or around the groove, and a high-frequency alternating current is applied. The alternating magnetic field generated by the coil induces eddy currents in the outer ring body, which is made of a magnetically conductive material (e.g., 40Cr alloy steel). This causes the outer ring to heat up and expand rapidly and uniformly due to the Joule effect, thereby relieving its radial pressure on the inner ring.

[0085] Alternatively, a magnetic ring made of a high-permeability material may be circumferentially embedded within the annular groove, preferably made of silicon steel sheet (electrical steel). This magnetic ring is firmly fixed to the groove by an interference fit or by high-temperature structural adhesive with a temperature resistance exceeding 300°C to ensure it does not loosen during repeated thermal cycling. In this configuration, when the external induction coil operates, the magnetic ring, due to its high permeability, highly concentrates the magnetic lines of force of the alternating magnetic field, thereby inducing eddy currents within itself that are much stronger than those in the outer ring body. These eddy currents are efficiently converted into Joule heat, causing the temperature of the magnetic ring to rise rapidly in a very short time. It then acts as a highly efficient built-in heat source, rapidly and concentratedly transferring heat to the outer ring body in close contact with it through thermal conduction, achieving precise and rapid heating of the target area of ​​the outer ring, greatly improving the response speed and energy efficiency of the thermal actuation process.

[0086] Furthermore, the boring bar includes: a bar body 1, a damping block 3 in the damping mechanism, and a constraint ring 4, which is a thermally actuated intelligent constraint ring 4.

[0087] The tool holder body 1 serves as the support and mounting structure, and a damping cavity 2 is machined inside it. The thermo-actuated intelligent constraint ring 4 is fixedly installed in the corresponding position within the damping cavity 2 of the tool holder body 1 using an interference fit. The vibration damping block 3 is disposed within the damping cavity 2, and its cylindrical surface is enveloped by the inner ring of the thermo-actuated intelligent constraint ring 4 in the axial middle section. By controlling the temperature of the thermo-actuated intelligent constraint ring 4, its radial locking force on the vibration damping block 3 can be changed, thereby achieving the fixing and locking (working state) or unlocking (maintenance state) of the vibration damping block.

[0088] The tool holder body 1 is made of high-strength 42CrMo alloy steel bar and manufactured using an integral molding process. Its structure is clearly divided into a working section 11, a vibration damping section 12, and a clamping section 13 along the axis. The sections are smoothly connected by stepped transition sections, i.e., stepped outer diameter transition sections, to ensure structural rigidity and avoid stress concentration.

[0089] Furthermore, the clamping section 13 is located at the rear end of the tool holder body 1, and it is equipped with a flange 19 for connection to the machine tool spindle. Its front end is a tapered section 18 with a large end diameter of Φ44.45 mm, a small end diameter of Φ40.2 mm, and a length L_holder = 60 mm (including the tapered section). The rear end is equipped with a flange 19 with an outer diameter of Φ63.55 (2×31.775) mm and a thickness T_flange = 16 mm.

[0090] Furthermore, the vibration damping section 12 is the core functional area of ​​the tool holder, with an outer diameter of Φ40.0 mm and a length of 135.4 mm.

[0091] A damping cavity 2 is machined forward along the axis (towards the working section) inside the cavity. This damping cavity 2 is a blind hole with a diameter of Φ29.020 mm and a depth of 120.4 mm. At the middle end of the damping cavity, an annular groove is machined for installing the thermally actuated intelligent constraint ring 4. This groove has a diameter of Φ28.980 mm and a depth of 20 mm. A 10 mm thick solid partition 14 is left between the front end face of the damping cavity 2 and the first stepped transition section 16 of the working section 11 to ensure structural strength. Between the rear end face of the cavity and the second stepped transition section 17 of the clamping section 13, there is also a solid cylindrical section with an outer diameter of Φ36.0 mm and a length of 5 mm, which is a solid partition 15, forming a rigid support for the opening end of the damping cavity.

[0092] Furthermore, the second step transition section 17: the rear end of the vibration damping section 12 transitions to the clamping section 13 through a tapered section 18, with a small end diameter of Φ40.0 mm (connecting to the vibration damping section), a large end diameter of Φ40.2 mm (connecting to the tapered small end of the clamping section), and a transition section length of L_transition1 = 25 mm.

[0093] Furthermore, the working section 11 is located at the very front of the tool holder body and is used to mount the boring head. Its main body has an outer diameter of Φ28.0 mm and a length of 25 mm.

[0094] First step transition section 16: The rear end of working section 11 transitions to the vibration damping section (12) through a conical surface. Small end diameter: Φ28.0 (connecting to the main body of the working section), large end diameter: Φ36.0 (connecting to the end face of the vibration damping section), transition section length: L_transition2 = 5mm.

[0095] Function and Effect: The tool holder body constitutes the rigid foundation and vibration transmission path of the entire system. The damping cavity designed within the vibration reduction section provides a space for the damping system. Its position and size have been dynamically optimized to apply the damping effect to the region with a large amplitude of the first-order bending mode of the tool holder, thereby most effectively improving the dynamic stiffness of the system.

[0096] Furthermore, the specifications and installation dimensions of vibration damper block 3 are as follows: Shape and Material: A solid cylinder made of a high-density tungsten-nickel-iron alloy with a density ≥17.5 g / cm³. 3 .

[0097] Dimensions and fit: Outer diameter D_damper = Φ16.000mm, length L_damper = 120mm. After installation in the damping cavity 2, a first axial clearance 21 (δ1) of approximately 0.2 mm is left between its front end face and the front end face of the damping cavity; a second axial clearance 22 (δ2) of approximately 0.2 mm is left between its rear end face and the rear end face of the cavity; except for the part that mates with the thermally actuated intelligent constraint ring 4, its cylindrical surface has a sufficiently large single-sided radial clearance with the inner wall of the damping cavity 2.

[0098] Working Principle and Function: The damping block acts as an inertial mass block in a tuned mass damper. When the tool holder vibrates, due to its elastic / frictional connection to the tool holder body 1 via the constraint ring 4 and its axial freedom at both ends, it will generate relative motion with the tool holder body under inertia. This relative motion dissipates vibration energy through friction at the constraint ring and internal material loss. If the damping block is made of composite material, it achieves the purpose of vibration reduction. The large radial clearance ensures that its inertial motion is unimpeded, while the axial clearance avoids rigid collisions and accommodates thermal expansion.

[0099] Furthermore, the manufacturing, assembly, and working principle of the thermally actuated intelligent constraint ring 4: The thermally actuated intelligent constraint ring 4 is a composite component, formed by joining an inner ring 41 and an outer ring 42 using a thermal fitting process. The inner ring 41 is made of YG8 cemented carbide, with an inner diameter d1 = Φ15.985 (+0.002 / 0), an outer diameter d2 = Φ23.000 (0 / -0.002), and a length L_inner = 20 mm. The coefficient of thermal expansion α1 ≈ 5.0 × 10⁻⁶. -6 / °C.

[0100] The outer ring 42 is made of 40Cr alloy steel. The inner diameter D2 = Φ22.960 (+0.015 / +0.005), outer diameter D3 = 29.000, and length L_outer = 20 mm. The coefficient of thermal expansion α2 ≈ 11.5 × 10⁻⁶ mm. -6 / °C. A ring-shaped groove 421, 1 mm deep and 3 mm wide, is machined in the middle of the outer cylindrical surface to serve as a heating interface.

[0101] Hot-fill composite process: Component composite: Due to the thermal expansion coefficient of the outer ring 42 α2≈11.5×10 -6 At room temperature, the outer ring's inner diameter is 22.975 mm. Heating from room temperature to 300°C expands the inner diameter to approximately Φ23.049 mm. When the inner ring 41 is placed inside, the outer ring's inner diameter D2_300 (≈ 23.049 mm) is much larger than the inner ring's outer diameter d2_min (22.998 mm). There is an assembly gap of approximately 0.051 mm between them, allowing for easy insertion. Upon cooling, the outer ring contracts, creating a radial interference of approximately 0.04 mm on the inner ring, placing it under pre-compression stress. Specifically, as the outer ring cools and contracts, its inner diameter attempts to revert to D2_20 (22.975 mm). However, because an inner ring with an outer diameter of 22.998 mm is already "stuck" inside, the outer ring cannot fully shrink back to its original size, and the inner ring's outer diameter cannot be compressed to less than 22.975 mm (otherwise, it would generate extremely high stress). Ultimately, the two reach a stress equilibrium state at 20°C. At this point, the deformation corresponding to the contact pressure can be equivalent to an "interference".

[0102] Installation to the tool holder: Press the composite constraint ring 4 into the precision fitting hole (Φ28.980 mm) of the tool holder body 1 with an interference of about 0.02 mm, and then use high-temperature epoxy adhesive to bond and cure to achieve fixation.

[0103] Relationship with the damping mechanism: After the constraint ring 4 is installed, its axis coincides with the axis of the damping cavity 2. The inner hole of its inner ring 41 envelops the middle section of the cylindrical surface of the vibration damping block 3.

[0104] Working principle and function: Locked State (Room Temperature, T_w=25°C): At room temperature, due to the restraint of the outer ring 42 on the pre-compressed inner ring 41, the inner hole of the inner ring 41 remains in a contracted state, with a diameter of approximately Φ15.991 mm, forming a radial interference fit of approximately 0.009 mm with the outer diameter (Φ16.000 mm) of the damper block 3. This interference generates sufficient radial locking force to firmly constrain the damper block 3 to the tool holder body, enabling it to effectively transmit and dissipate vibration energy.

[0105] Disassembly State (Heated to Disassembly Temperature T_r = 250°C): When the damper block 3 needs to be replaced or maintained, use a hot air gun to continuously and uniformly heat the outer ring 42 through the annular groove 421. Monitor its temperature with an infrared thermometer until it reaches the predetermined disassembly temperature of 250°C ± 10°C and maintain it for 1-2 minutes. The outer ring 42 expands significantly due to its high coefficient of thermal expansion, thereby relieving or greatly reducing the compressive stress on the inner ring 41. The inner ring 41 recovers its elasticity, and its inner hole expands to approximately Φ16.006 mm, creating a radial gap of approximately 0.006 mm between it and the outer diameter of the damper block 3. At this time, the damper block 3 can be easily removed from the cavity. The damping device can be gently pushed out from the center hole (if present) or side of the working section at the front end of the tool holder using a non-metallic push rod (such as a PEEK rod).

[0106] Restoring the locking force: After replacing the new damping block 3, the system cools down to room temperature and the locking force is automatically restored.

[0107] Effect: This design enables the vibration damping block 3 to be quickly installed, removed, and replaced (i.e., reconfigurable) without disassembling the tool holder body or performing destructive operations. At the same time, it ensures the high reliability and consistency of the locking force during operation, which is the core of the invention to achieve the functions of "intelligent" and "reconfigurable".

[0108] Work process: (1) Assembly: First, press the thermally actuated intelligent constraint ring 4 into the annular groove of the tool holder body 1. At room temperature, push the damping block 3 into the opening of the damping cavity 2 until it is locked by the inner ring of the constraint ring 4 with an interference fit of about 0.009 mm. An axial gap of about 0.2 mm is naturally formed at each end of the damping block.

[0109] (2) Machining (Work): The assembled boring bar is mounted on the machine tool spindle via the clamping section 13. During boring, when the tool bar vibrates, the locked damping block acts as an inertial mass block. Through its coupling with the tool bar body at the constraint ring, it consumes vibration energy and suppresses chatter.

[0110] (3) Maintenance / Reconfiguration: When it is necessary to replace the damping block (e.g., to adjust damping characteristics or due to device damage), stop machining and remove the tool holder. Heat the annular groove 421 area of ​​the outer ring of the constraint ring 4 to approximately 250°C using induction heating or other methods. At this time, the inner hole of the constraint ring expands, the locking force is released, and the old damping block can be removed. After installing the new damping block, cool it to room temperature, the locking force will automatically recover, and the tool holder can be put into use again.

[0111] Example 2: Optimization of Constraint Ring Installation Position The rest of the structure in this embodiment is the same as in Embodiment 1, except that the optimal installation position of the constraint ring is explored. This invention is not limited to this specific installation position; the constraint ring can be installed at any position on the entire damping block. This embodiment simply demonstrates that this specific position allows for further performance optimization.

[0112] To quantitatively determine the optimal installation position of the constraint ring 4 on the tool holder body 1, modal analysis and modal compliance calculation based on the finite element method were adopted.

[0113] First, a precise three-dimensional parametric model of the tool holder body 1 was established using the computer-aided engineering software ABAQUS. This model strictly adheres to the actual geometric dimensions and material properties of the clamping section 11, the vibration damping section 12, and the working section 13. Then, boundary conditions consistent with actual working conditions were applied to the model in the software; that is, fixed constraints were applied to the end face of the clamping section 11 to simulate its connection with the machine tool spindle. Modal analysis was performed to extract the first-order bending mode shape and its corresponding natural frequency of the tool holder.

[0114] To quantify the efficiency of applying unit stiffness at different axial positions in improving the overall dynamic stiffness of the system, numerical calculations based on modal compliance theory were further performed. This calculation, based on the aforementioned finite element modal analysis results, calculated the sensitivity of the displacement at each point along the tool holder axis to the unit constraint force (i.e., the modal compliance contribution) under the first-order bending mode, yielding a series of "constraint efficiency factors" corresponding one-to-one with the axial position. These "constraint efficiency factors" and their corresponding relative amplitude values ​​of the first-order bending mode were normalized relative to the tool holder overhang length and then plotted as follows: Figure 8 The comparison curves are shown, and the data are organized into quantitative data as shown in Table 1.

[0115] Analysis of the figure and table shows that the constraint efficiency factor reaches its peak at approximately 0.6 to 0.75 times the overhang length from the clamping end. This region highly coincides with the displacement overlying region of the first-order bending mode. This calculation theoretically proves that installing the constraint ring 4 within this specific range can maximize the improvement of the first-order modal dynamic stiffness of the tool holder system with minimal additional mass, thereby achieving the optimal vibration suppression design effect.

[0116] Table 1. Quantitative data on the comparison curves ; First-order bending mode shape: This visually displays the vibration pattern of the tool holder. The amplitude is 0 at the clamping end and reaches its maximum (1.0) at the tool tip.

[0117] Constraint efficiency factor: represents the strength of the effect of applying a unit stiffness constraint (e.g., installing a constraint ring) at this location on increasing the first natural frequency (i.e., dynamic stiffness) of the entire tool holder system.

[0118] Therefore, the installation position is selected as 0.6-0.75L, and the constraint ring is installed at a distance of approximately 0.6 to 0.75 times the overhang length of the tool holder from the clamping section.

[0119] The selection of this location stems from the classic theory of the first-order bending mode of a cantilever beam: for a homogeneous beam, the efficient operating region with an amplitude greater than 70% of the maximum amplitude is located approximately 0.65 times the length from the fixed end in its first-order bending mode. For engineering optimization of actual non-homogeneous boring bars (with varying diameters, cavities, etc.), the theoretical point is extended to a tolerance range to accommodate possible shifts in the mode shape.

[0120] This location is preferably based on a dual dynamic principle: First, this is the displacement zone of the first-order principal vibration mode of the tool holder. Applying rigid constraints here (such as the constraint ring of this invention) can most directly and effectively change the local curvature and overall dynamic stiffness of the structure, which is similar to applying suppression to the string segment with the strongest vibration. Second, according to modal theory, applying a unit stiffness to this displacement zone will do the most work on the generalized force of this mode, that is, the modal compliance contribution will be the most significant. Thus, the maximum change in the first-order dynamic characteristics of the system can be obtained with the least structural intervention cost, thereby achieving the optimal efficiency of vibration suppression design.

[0121] Meanwhile, this range explicitly avoids two types of inefficient or ineffective locations: first, the low-amplitude region near the clamping end, where applying constraints has little effect on changing the overall mode shape; and second, the potential second-order mode node region, where applying constraints is completely ineffective in suppressing the corresponding higher-order vibrations. Therefore, the coefficient range of 0.6 to 0.75 is a combination of theoretical core, engineering tolerance, and modal avoidance strategy, transforming the abstract concept of mode shape into key spatial coordinates guiding precise vibration suppression design.

[0122] Example 3: Selection of Constraint Ring Material The rest of the structure in this embodiment is the same as in embodiment 1, except that the material of the constraint ring is changed. The expansion coefficient of the outer ring 42 is greater than that of the inner ring 41.

[0123] Table 2. Material of Constraint Rings ; All of the above materials can be used to install the constraint ring and can be applied to this invention.

[0124] Example 4: Shock-absorbing block for a metal capsule The rest of the structure in this embodiment is the same as in Embodiment 1, except that the damping block is changed and the corresponding dimensions are optimized. In this embodiment, the damping block is a sealed metal capsule 3'. The metal capsule is cylindrical in shape, and its outer diameter matches the inner ring 41 of the damping cavity 2 and the constraint ring to ensure precise assembly.

[0125] The specific structure is as follows: Figure 9 As shown, the metal capsule consists of a capsule shell 31 and two end caps 321 and 322. The capsule shell 31 is a hollow, thin-walled cylindrical tube made of high-strength metal (such as alloy steel), and its wall thickness is optimized to ensure structural strength while maximizing internal space. The end caps are permanently sealed to the two ends of the shell 31 using precision welding processes such as electron beam welding or laser welding, forming a completely sealed inner cavity.

[0126] The core damping medium is as follows: A damping medium 33 is encapsulated within the sealed inner cavity. The damping medium 33 can be selected from particulate damping agents or high-viscosity damping fluids. Further, the particulate damping agent is selected from tungsten carbide, tungsten alloys, or ceramic microspheres. The particulate damping agent is a high-density solid particle, leaving a certain amount of free movement space within the capsule.

[0127] The high-viscosity damping fluid is selected from silicone-based gels or high-molecular viscoelastic fluids.

[0128] Working principle and advantages: When the tool holder system vibrates, the metal capsule 3' participates in the motion as an integral inertial mass block. Simultaneously, the damping medium 33 inside—whether solid particles or viscous fluid—will lag behind the capsule shell in relative motion due to inertial forces. This relative motion leads to intense collisions and friction between solid particles and between particles and the shell wall, or intense shearing and internal friction between viscous fluid molecules, thereby efficiently and irreversibly converting the system's vibrational mechanical energy into heat energy and dissipating it.

[0129] In summary, this embodiment integrates "inertial mass" and "distributed internal damping" into a compact sealed unit, realizing an advanced vibration reduction mechanism that combines high inertial effect and wide-bandwidth high dissipation characteristics, which is particularly suitable for suppressing cutting chatter with complex spectral characteristics.

[0130] The specific dimensions are as follows: The dimensions of the damping cavity 2 for accommodating the vibration damping block and the constraint ring 4 installed therein are designed as follows: 1. Dimensions of the damping cavity 2: The damping cavity 2 is a precision blind hole machined within the damping section 12 of the tool holder. Its diameter (D_cavity) and depth (H_cavity) are designed according to the overall dimensions of the damping device module it accommodates. When accommodating the metal capsule 3' and its constraint ring 4 as described in this embodiment, the cavity diameter (D_cavity) is preferably Φ29.020 (+0.015 / 0) mm to provide space for the interference fit of the outer ring of the constraint ring; its depth (H_cavity) is designed to be slightly larger than the axial length of the constraint ring 4 to ensure that the latter can be fully accommodated and fixed, while leaving a small gap or process space at the bottom. An exemplary depth is 20.6 mm, which is slightly larger than the length of the constraint ring, plus the sum of the front and rear micro-gap of approximately 0.6 mm.

[0131] A first solid partition 14 is provided between the open end of the damping cavity 2 and the working section 11. The axial thickness of the first solid partition 14 is not less than the diameter of the cavity to ensure that it has sufficient strength to transmit cutting torque and seal the cavity. Similarly, a second solid partition 15 is provided between the bottom of the cavity and the clamping section 13 to ensure that the capsule 3' and the constraint ring 4 can be fully accommodated and form reliable rigid support at both ends.

[0132] 2. Dimensions of the constraint ring mounting hole: A precision-fitting hole for mounting the thermally actuated smart constraint ring 4 is machined at the middle end of the damping cavity 2. The diameter (D_mount) of this hole is Φ28.980 (+0.005 / 0) mm, and the depth (L_mount) is equal to the axial length of the constraint ring 4, which is 20.0 mm.

[0133] 3. Specific dimensions of the metal capsule (3'): In some embodiments, the capsule shell 31 is a thin-walled cylindrical tube. Its outer diameter matches the inner hole design size of the inner ring 41 of the constraint ring, specifically D_capsule=Φ16.000 (0 / -0.002) mm, to ensure a reliable interference fit in the working state.

[0134] The wall thickness (t_shell) of the capsule shell 31 is optimized to simultaneously meet the requirements of structural strength and maximum volume. Preferably, the wall thickness (t_shell) and the wall thickness (t_inner) of the inner ring 41 of the constraint ring satisfy a proportional relationship: t_shell ≈ (0.2 ~ 0.5) * t_inner. Based on this proportional relationship and taking into account manufacturing manufacturability, an exemplary value for the wall thickness (t_shell) is 1.2 mm, with a tolerance of ±0.1 mm.

[0135] The inner diameter (D_inner_shell) of the capsule shell 31 is determined by the outer diameter (D_capsule) and the wall thickness (t_shell), with the relationship: D_inner_shell = D_capsule - 2 × t_shell. In one specific embodiment, the inner diameter of the shell is Φ13.60 mm. Considering the tolerances of the outer diameter and wall thickness, its actual processing range is between Φ13.40 mm and Φ13.80 mm. This inner diameter dimension provides optimized internal space for encapsulating the damping medium 33.

[0136] In some embodiments, the thickness (t_cap) of the end cap is designed to be no less than the wall thickness (t_shell) of the capsule shell 31 to ensure that the end cap has sufficient rigidity to withstand the heat effects of welding and sealing pressure. Preferably, the end cap thickness (t_cap) and the shell wall thickness (t_shell) satisfy a proportional relationship: t_cap ≈ (1.0 ~ 1.5) * t_shell. Based on this, an exemplary value for the end cap thickness (t_cap) is 1.5 mm, with a processing tolerance of ±0.1 mm.

[0137] The total axial length (L_total) of the metal capsule 3' needs to be slightly smaller than the axial length (L_inner) of the inner ring 41 of the constraint ring to ensure that the capsule is completely constrained in the inner ring hole and to prevent its end from protruding in the locked state. Preferably, the difference between the total length (L_total) and the inner ring length (L_inner), i.e., the axial assembly clearance, is no greater than 0.1 mm. In a specific embodiment, the inner ring length (L_inner) is 20.0 mm, the total length of the capsule (L_total) is set to 19.90 mm, and the machining tolerance is ±0.05 mm.

[0138] Based on the above dimensions, the axial length (L_cavity) of the sealed cavity inside the capsule shell 31 is determined by subtracting the thickness of the end caps from the total length. The calculated value is L_cavity = L_total - 2 × t_cap, which is approximately 17.0 mm.

[0139] 4. Damping Medium Filling Ratio: The filling ratio of the damping medium 33 is a key performance parameter. When the damping medium 33 is a particulate damping agent (such as tungsten carbide powder), its filling ratio in the sealed cavity (defined as the ratio of the total volume of the particles to the theoretical volume of the cavity) is optimized to be between 70% and 90%. This range ensures that: when the filling ratio is below 70%, the particles have too much room to move, resulting in insufficient collision frequency and energy dissipation efficiency; when the filling ratio is above 90%, the particle motion is excessively constrained and tends to "lock up," which also results in the loss of effective damping characteristics. Therefore, the filling ratio range of 70% to 90% is the preferred design window for achieving a wide-frequency, high-dissipation particle damping effect, ensuring that the particles have sufficient room to move to generate collision friction while maximizing inertial mass. The filling ratio is the soul of particle damper design.

[0140] Example 5: The damping block is a bimetallic composite cylinder. The rest of the structure in this embodiment is the same as in Embodiment 1, except that the damping block is changed and the corresponding dimensions are optimized. In this embodiment, the damping device 3 is a bimetallic composite cylinder 3''. The composite cylinder is cylindrical in shape, and its outer diameter matches the inner hole 41 of the damping cavity 2 and the constraint ring to ensure precise assembly.

[0141] The specific structure is as follows: Figure 10 As shown, the bimetallic composite cylinder 3'' is integrally formed from a first metal strip layer 34 and a second metal strip layer 35 through a solid-state composite process. The first metal strip layer 34 and the second metal strip layer 35 have significantly different coefficients of linear thermal expansion. The first metal strip layer (34) is an Invar alloy strip, and its average coefficient of linear thermal expansion α1 is not higher than 2.0 × 10⁻⁶. -6 / °C; the second metal strip layer (35) is a copper or copper alloy strip, and its average linear thermal expansion coefficient α2 is not less than 16.0×10 -6 / °C. The ratio of their thermal expansion coefficients, α2 / α1, is greater than 8. The two metal strips are metallurgically bonded at the composite interface along the axial or circumferential direction of the cylinder using either spiral welding or laminate welding processes, forming a dense, solid cylinder.

[0142] Working Principle and Advantages: During deep hole boring, the tool holder system generates a significant temperature rise field due to the cutting heat effect. When the bimetallic composite cylinder 3'' is in this temperature rise environment, due to the order-of-magnitude difference in the thermal expansion coefficients of its constituent materials, the copper strip layer 35 attempts to generate greater thermal expansion than the Invar alloy strip layer 34. This constrained non-uniform expansion induces complex microscopic cyclic alternating thermal stresses near the composite interface and within the two layers. This stress field drives the reciprocating motion of defects such as dislocations within the metal crystal, continuously converting mechanical energy into heat energy dissipation through the inherent viscoelastic internal friction mechanism of the material.

[0143] In summary, this embodiment creatively designs the passive inertial mass block as an energy conversion structure sensitive to operating temperature. It not only provides inertial mass macroscopically, but also actively generates additional damping forces synchronized with the temperature field by utilizing the heat energy generated during the cutting process microscopically, achieving a thermo-mechanical coupled intelligent damping that adapts to machining conditions. This provides a novel solution for maintaining stable vibration suppression performance in variable operating conditions or high-temperature cutting.

[0144] The specific dimensions are as follows: The outer diameter of the bimetallic composite cylinder 3'' matches the inner hole design size of the inner ring 41 of the constraint ring, specifically D_bimetal = Φ16.000 (0 / -0.002) mm, to ensure a reliable interference fit in the working state.

[0145] The total axial length (L_bimetal) of the bimetallic composite cylinder 3'' needs to be slightly smaller than the axial length (L_inner) of the inner ring 41 of the constraint ring to ensure that it is completely constrained in the inner ring hole. Preferably, the difference between the total length (L_bimetal) and the inner ring length (L_inner), i.e., the axial assembly clearance, is no greater than 0.1 mm. In a specific embodiment, the inner ring length (L_inner) is 20.0 mm, the total length (L_bimetal) of the composite cylinder is set to 19.90 mm, and the machining tolerance is ±0.05 mm.

[0146] The radial thicknesses of the first metal strip layer 34 and the second metal strip layer 35 can be designed collaboratively according to the strength requirements of the thermo-mechanical coupling damping effect. The sum of their thicknesses must satisfy the relationship: t_34 + t_35 = D_bimetal / 2. Preferably, the radial thickness of either strip layer is not less than 0.5 mm to ensure its structural integrity during the composite process and operation. By adjusting the ratio of the two layer thicknesses, the overall thermal expansion rate and internal thermal stress level of the composite under temperature rise can be adjusted, thereby achieving preliminary tuning of the thermo-mechanical coupling damping effect. In an exemplary design, to provide significant thermal stress excitation while ensuring good structural rigidity, the radial thickness of the Invar alloy strip layer 34 is designed to be 6.0 mm, and the radial thickness of the copper strip layer 35 is designed to be 2.0 mm. After the two are combined, they form a dense cylinder with an outer diameter of Φ16.000 mm.

[0147] The above are merely preferred embodiments of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A boring bar with a built-in detachable damping mechanism, characterized in that, The boring bar with the built-in detachable damping mechanism includes a bar body, which comprises a working section, a damping section, and a clamping section. One end of the damping section is connected to the working section, and the other end is connected to the clamping section. The damping section includes a damping mechanism, which includes: A damping cavity extends along the axial direction of the tool holder body; A constraint ring is disposed in the damping cavity; A vibration damping block is slidably inserted in the constraint ring. The end of the vibration damping block near the working section is provided with a first axial gap, and the end of the vibration damping block near the clamping section is provided with a second axial gap.

2. The boring bar with a built-in detachable damping mechanism according to claim 1, characterized in that, A first partition structure is provided between the shock-absorbing section and the working section, and / or a second partition structure is provided between the shock-absorbing section and the clamping section; preferably, the first partition structure includes a first stepped transition section and a first solid partition; and / or the second partition structure includes a second stepped transition section and a second solid partition.

3. The boring bar with a built-in detachable damping mechanism according to claim 1, characterized in that, Both the first axial clearance and the second axial clearance are 0.05-0.4 mm. Preferably, the first axial clearance and the second axial clearance are set to be equal.

4. The boring bar with a built-in detachable damping mechanism according to claim 1, characterized in that, The outer surface of the constraint ring is interference-fitted with the inner wall of the damping cavity, and the interference amount of the interference fit is 0.01-0.03 mm.

5. The boring bar with a built-in detachable damping mechanism according to any one of claims 1-4, characterized in that, The shock-absorbing block is designed to match the inner hole size of the constraint ring, and its length is more than twice the length of the constraint ring.

6. The boring bar with a built-in detachable damping mechanism according to claim 5, characterized in that: The damping block is a cylinder, which is selected from a solid cylinder, a sealed metal capsule, or a bimetallic composite cylinder. Preferably, the solid cylinder is made of a high-density alloy material, the sealed metal capsule contains a damping agent, and the bimetallic composite cylinder is formed by rolling or stacking two layers of metal strips with different coefficients of thermal expansion.

7. The boring bar with a built-in detachable damping mechanism according to any one of claims 1-4 or 6, characterized in that: The constraint ring includes: Inner ring, wherein the inner ring is slidably disposed with respect to the damping block; An outer ring is located circumferentially around the inner ring.

8. The boring bar with a built-in detachable damping mechanism according to claim 7, characterized in that: The expansion coefficient of the outer ring is greater than that of the inner ring. Preferably, the inner ring is made of YG8 cemented carbide and the outer ring is made of 40Cr alloy steel.

9. The boring bar with a built-in detachable damping mechanism according to claim 8, characterized in that: The outer ring is provided with a heating interface in its circumferential direction.

10. The assembly method of the boring bar with the built-in detachable damping mechanism as described in claims 1-9, comprising the following steps: (1) The constraint ring is semi-permanently fixed to the inner wall of the middle end of the damping cavity; (2) Insert the damping block through the opening of the damping cavity, slide it through the constraint ring, and push it to the bottom of the damping cavity; The semi-permanent fixation is selected from one of interference fit, interference fit and chemical bonding.

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