A honing and reaming integrated precision machining tool for a difficult-to-machine material inner hole and a method of using the same

Abstract

The application discloses a kind of difficult-to-machine material inner hole hinge honing integrated precision machining tool and its using method, hinge cutting component and honing component are integrated in the same tool bar front end along tool axial direction, and the hinge cutting and honing of workpiece inner hole are continuously completed in one clamping or one feeding process.Pressure fluid enters piston cavity and then pushes piston to drive taper along axial movement, and through the cooperation of taper surface between taper and oil stone seat, oil stone is driven to expand radially, and honing machining is realized.Honing size fine adjustment mechanism adjusts the axial limiting position of taper, changes the effective cooperation depth between taper and oil stone seat, adjusts the radial expansion amount of oil stone, and realizes the precision fine adjustment of hole diameter.Supply liquid guide structure guides pressure fluid to first and second spray outlets, respectively used for flushing workpiece inner hole wall and machining area, and flushing the surface of oil stone attached to abrasive dust.The machining tool can reduce process conversion, improve the size consistency, chip removal capacity and machining stability of precision hole machining of titanium alloy and other difficult-to-machine materials.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for internal holes of difficult-to-machine materials, and in particular to a continuous precision machining tool and method for reaming and honing internal holes of hard and brittle materials. It integrates continuous machining of reaming and honing into one tool and can be used for high-precision machining of internal holes of difficult-to-machine materials such as titanium alloys, stainless steel, and high-temperature alloys. Background Technology

[0002] In the fields of aerospace, precision equipment and high-end machinery manufacturing, parts made of difficult-to-machine materials such as titanium alloys often have high-precision internal hole structures. Such internal holes usually have high requirements for dimensional accuracy, roundness, cylindricity and surface quality. In traditional machining methods, internal holes usually need to go through multiple processes such as drilling, reaming, boring, grinding or honing. The machining process involves multiple tool changes, repeated clamping or equipment switching, which can easily introduce positioning errors and clamping errors, affecting the consistency and efficiency of internal hole machining. Moreover, existing internal hole machining centers can usually complete drilling, boring and other machining independently, but there are the following problems: (1) It is difficult to efficiently connect the reaming and honing processes. Therefore, it is difficult to achieve continuous precision machining of internal holes on the machining center. (2) Due to the relatively enclosed nature of the internal hole machining area, the cooling, lubrication, and chip removal conditions in the contact area between the honing stone and the hole wall are limited. Coolant or lubricant cannot fully reach the contact area between the tool and the hole wall, and cutting heat and grinding chips are not easily discharged in time. Grinding chips tend to remain and adhere to the contact area between the honing stone and the hole wall, which can easily aggravate honing stone blockage and wear. The effective abrasive grains' ability to participate in cutting decreases, leading to problems such as decreased material removal rate, poor stability of hole diameter increment, and surface quality fluctuations. It may also cause problems such as surface roughness fluctuations, hole wall scratches, or decreased consistency of the machined surface. (3) The ability of any single machining method to further improve the surface quality and geometric accuracy of the internal hole is limited. For example, when reaming is used alone, although it can improve the hole diameter and hole wall morphology, its ability to further improve the cylindricity of the internal hole, surface micro-texture, and machining damage layer is limited. When honing is used alone, special honing equipment or independent honing tools are usually required, which makes it difficult to efficiently connect with the original machining process of the machining center.

[0003] Therefore, it is necessary to propose an integrated precision machining tool that is integrated into the same machining center spindle, can simultaneously realize continuous machining of reaming and honing processes, and improves the dimensional consistency of the machined hole diameter, the chip removal capability and machining stability. Summary of the Invention

[0004] To address the problems of separate reaming and honing processes in existing precision internal hole machining, such as low machining efficiency, large repeated clamping and positioning errors, insufficient cooling and lubrication, poor chip removal, easy clogging of honing stones, low material removal rate, and poor surface quality stability in machining difficult-to-machine materials like titanium alloys, this invention proposes an integrated precision machining tool for reaming and honing difficult-to-machine materials and its usage method. This tool can be directly mounted on the spindle of a machining center, continuously performing reaming and honing of the workpiece's internal hole on the same tool. It utilizes pressurized fluid to drive the radial expansion of the honing stone, and cools, flushes, and removes chips from the machining area and the honing stone surface, thereby improving internal hole machining efficiency, hole diameter control, and surface quality stability.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An integrated precision machining tool for reaming and honing the inner hole of a difficult-to-machine material includes a tool holder, a tool shank, a reaming assembly, a honing assembly, a honing dimension fine-tuning mechanism, and a fluid supply and guiding structure. The tool holder is located at the rear end of the tool shank and is used to connect to the spindle of a machining center; an internal channel for pressurized fluid flow is formed inside the tool shank; the reaming assembly and the honing assembly are sequentially arranged at the front end of the tool shank along the tool axis, and along the tool feed direction, the reaming assembly is located in front of the honing assembly, enabling the machining tool to sequentially complete the reaming and honing of the workpiece's inner hole in a single clamping or single feed.

[0007] Preferably, the tool holder has a tool holder flange at its front end, and the tool shank has a tool shank flange at its rear end that mates with the tool holder flange. A radial adjusting screw, an axial adjusting screw, and a connecting screw are provided between the tool holder flange and the tool shank flange. The connecting screw is used to pre-tighten the tool holder flange and the tool shank flange, and to lock the tool holder and tool shank together after runout adjustment. The radial adjusting screw is used to adjust the radial position of the tool shank relative to the tool holder in the pre-tightened connection state, thereby adjusting the radial runout and coaxiality of the machining tool. The axial adjusting screw is used to adjust the end face posture of the tool shank relative to the tool holder in the pre-tightened connection state, thereby adjusting the end face runout of the machining tool. This structure allows for adjustment of the installation accuracy of the reaming and honing assemblies relative to the machining center spindle axis before tool assembly or use, thereby improving the dimensional consistency and geometric accuracy of internal hole machining.

[0008] The reaming assembly includes a reaming insert and a reaming seat for positioning and mounting the reaming insert. The reaming insert is disposed on the outer periphery of the reaming seat and is used for reaming the inner hole of the workpiece. Preferably, the reaming assembly also includes a locating pin and a fixing bolt. The reaming seat has an insert mounting part, and the reaming insert is positioned on the reaming seat by the locating pin and fixed by the fixing bolt. With this structure, the reaming insert can achieve high installation and positioning accuracy and working stability, providing a better foundation for the hole diameter and geometry for subsequent honing.

[0009] The honing assembly includes a piston, a hollow screw, a tapered rod, a honing stone, and a honing stone holder. The piston is located within a piston chamber, which communicates with the internal channel of the tool holder. Pressurized fluid enters the piston chamber and acts on the pressure-bearing end face of the piston, driving it to move axially along the tool. The hollow screw connects the piston to the tapered rod and transmits the piston's axial movement to the tapered rod. A tapered surface fit is formed between the tapered rod and the honing stone holder. The honing stone is mounted on the outside of the honing stone holder. The axial movement of the tapered rod is converted into radial expansion of the honing stone holder through the tapered surface fit, causing the honing stone to extend radially and form honing contact with the inner wall of the workpiece's bore, thereby performing honing processing on the workpiece's inner bore.

[0010] The honing dimension fine-tuning mechanism is used to adjust the axial limit position of the cone rod to change the effective axial working stroke of the cone rod, thereby changing the axial wedging amount of the cone rod relative to the honing stone seat, causing the radial expansion amount of the honing stone seat and the honing stone to change, thus achieving precise fine-tuning of the honing hole diameter.

[0011] Specifically, the honing dimension fine-tuning mechanism includes a fine-tuning screw and a fine-tuning limit block. The fine-tuning limit block is located at the axial movement termination position of the tapered rod. The fine-tuning screw drives the fine-tuning limit block to move along the tool axis, thereby changing the axial limit position of the tapered rod. By adjusting the position of the fine-tuning limit block, the maximum axial displacement of the tapered rod can be changed, thereby adjusting the final radial expansion of the honing stone and achieving precise control of the honing hole diameter.

[0012] Preferably, the fine-tuning screw has a first threaded section and a second threaded section. The first threaded section is threadedly engaged with a fixed support on the reamer or tool holder, and the second threaded section is threadedly engaged with a fine-tuning limit block. The first and second threaded sections have the same direction of rotation but different pitches, so that when the fine-tuning screw rotates, the fine-tuning limit block generates a differential displacement relative to the fixed support along the tool axis, thereby improving the adjustment resolution of the axial position of the fine-tuning limit block. The honing dimension fine-tuning mechanism may also include an anti-rotation screw, which engages with the fine-tuning limit block to restrict the fine-tuning limit block from rotating with the fine-tuning screw, allowing the fine-tuning limit block to move along the tool axis when the fine-tuning screw rotates.

[0013] The fluid supply and guiding structure is used to guide pressurized fluid to the piston drive area, the workpiece inner hole wall machining area, and the whetstone surface rinsing area. The fluid supply and guiding structure includes a piston chamber, a bypass guiding channel, a tapered rod central channel, a first spray outlet, and a second spray outlet. Pressurized fluid enters the piston chamber through the internal channel of the tool holder and acts on the pressure-bearing end face of the piston to drive the piston to move axially along the tool. A portion of the pressurized fluid enters the tapered rod central channel through the hollow screw and is ejected from the first spray outlet to cool, rinse, and remove chips from the workpiece inner hole wall machining area. Another portion of the pressurized fluid flows through the bypass guiding channel to the second spray outlet and is ejected from the second spray outlet to remove grinding debris adhering to the whetstone surface.

[0014] Preferably, the fluid supply and guiding structure further includes a guide screw, which is located at the end of the central channel of the cone rod to block the end of the central channel, allowing the pressurized fluid entering the central channel to be preferentially ejected from the first nozzle. The first nozzle is positioned towards the machining area of ​​the workpiece's inner bore wall to flush the inner bore wall and remove machining debris; the second nozzle is positioned towards the surface of the honing stone to flush away the grinding debris adhering to the surface of the honing stone. Through the above-mentioned fluid supply and guiding structure, the pressurized fluid not only serves as the driving medium for the radial expansion of the honing assembly but also as a cooling, flushing, and chip removal medium during the machining process, which helps to reduce the accumulation of cutting heat, reduce grinding debris retention, and alleviate honing stone clogging and wear.

[0015] The present invention also provides a method for using an integrated precision machining tool for reaming the inner hole of a difficult-to-machine material, comprising the following steps:

[0016] S1. Mount the machining tool onto the machining center spindle via the tool holder, and use the connecting screws to ensure the tool holder flange and the tool bar flange are in a pre-tight connection state; then adjust the radial adjusting screws to ensure the radial position of the tool bar relative to the tool holder meets the requirements for coaxiality and radial runout; then adjust the axial adjusting screws to ensure the end face runout of the machining tool meets the machining requirements; after adjustment, lock and fix the tool holder and tool bar with the connecting screws.

[0017] S2. Adjust the honing dimension fine-tuning mechanism according to the target size of the hole to be machined to determine the axial limit position of the tapered rod;

[0018] S3. Start the machining program and turn on the pressure fluid supply, so that the pressure fluid enters the piston chamber and acts on the pressure end face of the piston, pushing the piston to drive the cone rod to move along the tool axis, causing the oilstone seat and oilstone to expand radially.

[0019] S4. The machining tool feeds along the inner hole of the workpiece. The reaming assembly first reams the inner hole of the workpiece, and then the honing assembly hones the surface of the reamed inner hole.

[0020] S5. During the processing, the pressurized fluid is ejected from the first nozzle through the central channel of the cone rod to cool, flush and remove chips from the processing area of ​​the inner hole wall of the workpiece; the pressurized fluid is ejected from the second nozzle through the bypass guide channel to wash away the grinding debris attached to the surface of the oilstone.

[0021] S6. After processing is completed, release or reduce the pressure fluid driving action to allow the oilstone to retract radially to the yielding state and detach from the inner wall of the workpiece. Then, allow the processing tool to exit the inner hole of the workpiece to prevent scratching the surface of the inner hole of the workpiece during the exit process.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] This invention integrates the reaming and honing components onto the same machining tool, enabling continuous reaming and honing of workpiece inner holes on a machining center. This reduces tool changes, repetitive positioning, or equipment switching, improves machining efficiency, and reduces positioning and clamping errors introduced by multi-process connections.

[0024] This invention first reams the inner hole of the workpiece using a reaming assembly, and then hones the hole wall after reaming using a honing assembly. This facilitates the continuous connection between the basic machining of the hole diameter and the improvement of surface quality, thereby improving the consistency of the inner hole machining.

[0025] This invention, by setting an adjustable flange connection structure between the tool holder and the tool shank, can adjust the radial runout, coaxiality, and end face runout of the machining tool, improve the installation accuracy of the reaming assembly and honing assembly relative to the spindle axis of the machining center, and help improve the consistency of inner hole roundness, cylindricity, and hole diameter machining.

[0026] This invention uses a pressure fluid to drive the piston and cone rod, enabling the oilstone seat and oilstone to expand radially outward during processing and form honing contact with the hole wall. It can make full use of the internal cooling fluid supply system of the machining center, has a compact structure, and is suitable for precision machining of internal holes in machining centers.

[0027] This invention provides a honing dimension fine-tuning mechanism that adjusts the axial limit position of the cone rod to change the radial expansion of the honing stone, thereby achieving precise fine-tuning of the honing hole diameter, which is beneficial to improving the hole diameter control capability and processing repeatability.

[0028] This invention, by setting up a tapered rod center channel, a bypass guide channel, a first spray outlet, and a second spray outlet, enables pressurized fluid to cool, flush, and remove chips from the machining area of ​​the workpiece's inner hole wall and the surface of the whetstone, thereby reducing the accumulation of cutting heat and the retention of grinding chips, reducing the risk of whetstone blockage and wear, and improving the stability of material removal and surface quality.

[0029] This invention retracts the whetstone radially to a yielding state after processing, and then withdraws the processing tool from the inner hole of the workpiece, which can prevent the whetstone from continuously pressing against the hole wall and scratching the processed surface during the withdrawal process.

[0030] Therefore, this invention is applicable to high-precision machining of internal holes in difficult-to-machine materials such as titanium alloys, and can take into account machining efficiency, dimensional control capability, cooling and chip removal capability, and surface quality stability. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 yes Figure 1 The left view;

[0033] Figure 3 yes Figure 2 AA partial sectional view;

[0034] Figure 4 yes Figure 2 Partial sectional view of BB;

[0035] Figure 5 yes Figure 3 CC section view;

[0036] Figure 6 This is a schematic diagram of the processing procedure of the present invention;

[0037] Figure 7 This is a comparison graph of the temperature change curves of the inner wall of the workpiece during the processing of Example 1;

[0038] Figure 8 This is a comparison graph of the material removal rate changes of the workpiece during the processing of Example 1.

[0039] Key reference numerals in the attached drawings: 1-Tool holder, 11-Tool holder flange, 2-Tool bar, 21-Tool bar flange, 22-Connecting screw, 23-Axial adjusting screw, 24-Radial adjusting screw, 3-Reaming assembly, 31-Reaming insert, 32-Positioning pin, 33-Reaming seat, 34-Fixing bolt, 41-Piston, 42-Hollow screw, 43-Conical rod, 44-Washstone, 45-Washstone seat, 46-Coil spring, 47-Reset spring, 48-Limiting ring, 51-Fine-adjusting screw, 511-First threaded section, 512-Second threaded section, 52-Fine-adjusting limit block, 53-Anti-rotation screw, 61-Piston chamber, 62-Bypass flow channel, 63-Conical rod center channel, 64-First nozzle, 65-Second nozzle, 66-Flow guide screw. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings. It should be noted that the following embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Equivalent substitutions, modifications, or improvements made by those skilled in the art based on the technical concept of the present invention should all fall within the scope of protection of the present invention.

[0041] Example 1

[0042] like Figures 1-5 As shown, an integrated precision machining tool for reaming and honing internal holes of difficult-to-machine materials includes a tool holder 1, a tool shank 2, a reaming assembly 3, a honing assembly 4, a honing dimension fine-tuning mechanism, and a fluid supply and guiding structure. The tool holder 1 is used to connect to the spindle of a machining center, and the tool shank 2 is connected to the front end of the tool holder 1 and serves as the mounting base for all functional components. The tool shank 2 has a pressure fluid channel extending through the tool's axial direction to provide driving force to the honing assembly and to deliver pressure fluid to the fluid supply and guiding structure.

[0043] Along the tool feed direction, the reaming assembly 3 is positioned at the front end of the tool holder 2, and the honing assembly is positioned behind the reaming assembly 3. After the machining tool enters the inner hole of the workpiece, reaming and honing are performed sequentially. The reaming assembly 3 is used to correct the bottom hole size and geometry, providing a uniform and stable machining allowance for subsequent honing. The honing assembly 4 further improves the dimensional accuracy, roundness, cylindricity, and surface quality of the inner hole. By integrating reaming and honing into the same machining tool and arranging them sequentially along the tool axis, two machining operations can be completed continuously in a single clamping and feed cycle, reducing tool changes and repetitive positioning errors, improving machining efficiency, and ensuring the continuous inheritance of machining accuracy.

[0044] like Figure 1 , 2 As shown in Figure 3, the tool holder 1 and the tool shank 2 are connected by a flange structure. The tool holder 1 has a tool holder flange 11 at its front end, and the tool shank 2 has a tool shank flange 21 at its rear end that mates with the tool holder flange 11. A radial adjusting screw 22, an axial adjusting screw 23, and a connecting screw 24 are located between the two flanges. During assembly, the two flanges are first pre-tightened using the connecting screw 24. Then, the radial position of the tool shank 2 relative to the tool holder 1 is finely adjusted using the radial adjusting screw 22 to correct the radial runout and coaxiality of the machining tool. Subsequently, the axial adjusting screw 23 is adjusted to adjust the installation posture of the tool shank 2 to correct the end face runout of the machining tool. After the installation accuracy meets the requirements, the connecting screw 24 is finally tightened to complete the locking. Through the above adjustment method, the reaming assembly 3 and the honing assembly 4 can maintain a unified rotational reference, improving the overall installation accuracy of the machining tool and providing a stable and reliable motion basis for precision machining of internal holes.

[0045] like Figure 2 , 3 As shown in Figure 4, the reaming assembly 3 includes a reaming seat 33, a reaming insert 31, a locating pin 32, and a fixing bolt 34. The reaming seat 33 is fixedly installed on the front end of the tool holder 2. The reaming insert 31 is installed on the outer periphery of the reaming seat 33 and positioned by the locating pin 32 and locked by the fixing bolt 34. The locating pin 32 is used to ensure the installation position accuracy of the reaming insert 31, and the fixing bolt 34 is used to provide reliable clamping force to ensure that the reaming insert 31 maintains stable operation under cutting load. During the machining process, the reaming insert 31 first removes the reserved machining allowance of the inner hole of the workpiece, corrects the hole diameter and geometric errors, and establishes a uniform machining foundation for subsequent honing, thereby improving the stability of honing and the final machining quality.

[0046] like Figure 3 , 4As shown, the honing assembly constitutes the pressure fluid driven actuator of the present invention, including a piston 41, a hollow screw 42, a tapered rod 43, a honing stone 44, a honing stone seat 45, a return spring 46, and a limiting retaining ring 47. The piston 41 is disposed in the piston chamber 61 and can move axially along the tool axis. The front end of the piston 41 is connected to the tapered rod 43 through the hollow screw 42. While transmitting axial thrust, the hollow screw 42 also serves as a fluid channel for the pressure fluid to enter the central channel 63 of the tapered rod.

[0047] like Figure 3 , 4 As shown in Figure 5, the tapered rod 43 is positioned along the tool axis, with its rear end inserted into the shaft hole of the fine-tuning limit block 52, forming a guiding fit with the fine-tuning limit block 52. This ensures that the tapered rod 43 remains coaxial with the tool axis during movement, allowing it to move only axially, thus guaranteeing smooth movement and the accuracy of honing stone expansion. The tapered rod 43 has a tapered surface on its outer periphery, and the honing stone seat 45 is fitted around the tapered rod 43, forming a tapered surface fit with it. The honing stone 44 is fixedly installed on the outside of the honing stone seat 45. When the tapered rod 43 moves forward along the tool axis, the tapered surface acts on the honing stone seat 45, causing the honing stone seat 45 to move outward and driving the honing stone 44 to extend radially, forming a stable contact with the inner wall of the workpiece, thereby establishing the radial pressure required for honing.

[0048] The limiting ring 48 is used to limit the retraction position of the piston 41 and limit the maximum retraction stroke of the tapered rod 43, ensuring that the tapered rod 43 and the fine-tuning limiting block 52 are always in a shaft-hole fit state throughout the machining process. During the machining process, after the pressurized fluid enters the piston chamber 61, it acts on the pressure end face of the piston 41, pushing the piston 41 to move along the tool axis. The piston 41 drives the tapered rod 43 to move forward synchronously through the hollow screw 42. The tapered rod 43 further drives the honing stone seat 45 to expand radially through the tapered surface fit, so that the honing stone 44 presses against the inner wall of the workpiece to complete the honing process.

[0049] After machining is completed, the supply of pressurized fluid is stopped, piston 41 loses its pressure driving force, and return spring 46 releases its elastic potential energy, pushing piston 41, hollow screw 42, and tapered rod 43 to move in the opposite direction along the axial direction. As tapered rod 43 retracts, oilstone seat 45 retracts inward simultaneously, oilstone 44 returns to its retracted state and detaches from the inner wall of the workpiece hole, and then the machining tool withdraws from the inner hole of the workpiece, thereby avoiding scratching the machined hole wall during the withdrawal process.

[0050] Therefore, this embodiment utilizes the pressure fluid provided by the internal cooling system of the machining center as the driving force. Through the power transmission path of "pressure fluid - piston - hollow screw - tapered rod - honing stone seat - honing stone", the pressure energy provided by the pressure fluid is converted into the radial expansion motion of the honing stone 44, realizing the automatic establishment and automatic release of honing pressure. This unifies the power drive, honing execution and automatic return in the same actuator, improving machining stability, machining accuracy and reliability while ensuring structural compactness.

[0051] like Figure 5 As shown, the honing dimension fine-tuning mechanism is used to adjust the final expansion position of the honing assembly 4 to achieve precise control of the honing hole diameter. The honing dimension fine-tuning mechanism includes a fine-tuning screw 51, a fine-tuning limit block 52, and an anti-rotation screw 53.

[0052] A fine-tuning limit block 52 is located behind the tapered rod 43, and its center has a guide shaft hole that mates with the tapered rod 43 to guide the tapered rod 43 and limit its movement along the tool axis. A fine-tuning screw 51 is connected to the fine-tuning limit block 52. The fine-tuning screw 51 has a first threaded section 511 and a second threaded section 512. The first threaded section 511 is threadedly engaged with the reamer 33, and the second threaded section 512 is threadedly engaged with the fine-tuning limit block 52. The two threaded sections have the same direction of rotation and use similar but unequal pitches, forming a differential thread drive through the pitch difference. An anti-rotation screw 53 is used to limit the rotation of the fine-tuning limit block 52 with the fine-tuning screw 51, ensuring that the fine-tuning limit block 52 moves only along the tool axis.

[0053] When the fine-tuning screw 51 is rotated, the first threaded section 511 and the second threaded section 512 form a differential threaded transmission, causing the fine-tuning limit block 52 to produce a slight displacement along the tool axis, thereby adjusting the axial limit position of the tapered rod 43. During the machining process, the tapered rod 43 moves along the tool axis under the drive of pressurized fluid, and its maximum axial working stroke is determined by the axial position of the fine-tuning limit block 52; the axial displacement of the tapered rod 43 is converted into the radial expansion of the honing stone 44 through the tapered surface transmission, thereby realizing the precise adjustment of the honing hole diameter.

[0054] The axial differential displacement Δx of the fine-tuning limit block 52 relative to the reamer 33 satisfies:

[0055] Δx=(θ / 360°)·|P1-P2|

[0056] In the formula, Δx is the axial differential displacement of the fine-tuning limit block 52 relative to the reaming seat 33, θ is the rotation angle of the fine-tuning screw 51, P1 is the pitch of the first thread segment 511, and P2 is the pitch of the second thread segment 512.

[0057] The axial displacement of the tapered rod 43 is converted into the radial expansion displacement of the oilstone 44 via the tapered surface transmission. The theoretical aperture increment ΔD corresponding to the radial expansion of the oilstone 44 satisfies:

[0058]

[0059] In the formula, ΔD is the theoretical pore size increment corresponding to the radial expansion of the oilstone 44. θ is the radial expansion of the oilstone on one side, θ is the rotation angle of the fine-tuning screw 51, P1 is the pitch of the first threaded section 511, P2 is the pitch of the second threaded section 512, and α is the half-cone angle of the mating cone surface of the cone rod 43 and the oilstone seat 45.

[0060] In this embodiment, the pitches of the first threaded section 511 and the second threaded section 512 are P1 = 0.5 mm and P2 = 0.4 mm, respectively, and the conical surface parameter of the tapered rod 43 satisfies tanα = 0.25. The fine-tuning screw 51 is set with 50 equally divided graduations along the circumference. Each graduation corresponds to a rotation angle θ = 7.2°. At this time, the axial differential displacement Δx generated by the fine-tuning limit block 52 is 0.002 mm. After conversion by the conical surface transmission, the single-sided radial expansion Δr of the honing stone 44 is 0.5 μm, corresponding to a theoretical hole diameter increment ΔD = 1 μm. Therefore, quantitative adjustment through the graduations of the fine-tuning screw 51 can achieve micron-level precision adjustment of the honing hole diameter, improving the accuracy of dimensional adjustment and operational convenience.

[0061] The anti-rotation screw 53 cooperates with the fine-tuning limit block 52 to limit the fine-tuning limit block 52 from rotating synchronously with the fine-tuning screw 51, so that the fine-tuning limit block 52 moves only along the tool axis. Through the above structure, the adjustment resolution and repeatability of the fine-tuning mechanism can be effectively improved, enabling the machining tool to quickly complete the size adjustment according to the machining requirements of different hole diameters, and ensuring the consistency of dimensions after multiple adjustments.

[0062] The fluid supply and guiding structure comprises a piston chamber 61, a bypass guiding channel 62, a conical rod center channel 63, a first spray outlet 64, a second spray outlet 65, and a guiding screw 66, used to realize the delivery, diversion, and directional injection of pressurized fluid. During machining, the pressurized fluid enters the internal fluid channel of the tool holder 2 from the internal cooling system of the machining center, and first enters the piston chamber 61, applying axial thrust to the piston 41 to provide driving force for the honing assembly. After the pressurized fluid completes its driving action, two fluid paths are formed within the fluid supply and guiding structure.

[0063] One of the pressurized fluids enters the central channel 63 of the tapered rod through the hollow screw 42. Under the guidance of the guide screw 66, it is ejected from the first nozzle 64 and directly acts on the machining area of ​​the inner hole wall of the workpiece to cool, lubricate and flush the machining area, and promptly remove the grinding debris and cutting residue generated during the machining process, thereby reducing the temperature rise of the machining area and improving the machining conditions.

[0064] Another pressure fluid flows through the bypass guide channel 62 to the second spray outlet 65 and is sprayed onto the working surface of the oilstone 44 to continuously wash the grinding debris attached to the surface of the oilstone 44, so that the grinding debris is removed from the working surface of the oilstone in time, reducing the phenomenon of grinding debris blockage and accumulation, maintaining the good cutting ability of the oilstone 44, and improving the stability of material removal and the consistency of the surface quality of the machined surface.

[0065] Thus, the pressure fluid forms an integrated working mode of "driving-cooling-lubrication-chip removal" in this invention. That is, the pressure fluid first drives the honing assembly 4 to complete the radial expansion of the honing stone 44, and then acts on the machining area of ​​the inner hole wall of the workpiece and the working surface of the honing stone 44 respectively, realizing the unification of driving function and machining auxiliary function, giving full play to the role of the internal cooling system of the machining center, improving the utilization efficiency of pressure fluid, and simplifying the overall structure of the machining tool.

[0066] When machining the inner hole of a workpiece using the above-mentioned machining tool, firstly, according to the size requirements of the hole to be machined, the axial limit position of the tapered rod 43 is adjusted by the honing size fine adjustment mechanism 5 so that the honing stone 44 has the corresponding maximum radial expansion; then, the machining tool is installed on the spindle of the machining center, and the installation accuracy of the machining tool is adjusted by the flange connection structure between the tool holder 1 and the tool bar 2.

[0067] like Figure 6 As shown, after machining begins, the machining center spindle drives the machining tool to rotate. Simultaneously, pressurized fluid enters the machining tool, driving the piston 41, hollow screw 42, and tapered rod 43 to move along the tool's axial direction. The tapered rod 43, through the action of its conical surface, pushes the honing stone seat 45 to expand radially, causing the honing stone 44 to press against the inner wall of the workpiece's hole to establish honing pressure. During the machining tool's axial feed along the inner hole of the workpiece, the reaming assembly 3 at the front end first completes the inner hole reaming, correcting the bottom hole size and geometric errors. Subsequently, the honing assembly 4 at the rear immediately hones the reamed hole wall, achieving hole diameter correction, geometric accuracy improvement, and surface quality enhancement.

[0068] Throughout the entire processing, the fluid supply and guiding structure continuously delivers pressurized fluid to the machining area of ​​the inner hole wall of the workpiece and the working surface of the honing stone 44, which cools, lubricates, flushes and removes chips from the machining area, so that the grinding chips generated during machining can be discharged in time, reducing the risk of honing stone blockage and improving the stability of honing.

[0069] After machining is completed, the pressurized fluid supply is stopped, piston 41 loses its pressure driving force, and return spring 46 pushes piston 41, hollow screw 42, and tapered rod 43 back axially. Oilstone seat 45 retracts synchronously with tapered rod 43, and oilstone 44 returns to its retracted state and detaches from the inner wall of the workpiece hole. Subsequently, the machining tool withdraws from the inner hole of the workpiece, thus preventing oilstone 44 from scraping against the machined hole wall during withdrawal, improving the surface integrity of the workpiece hole and the machining quality.

[0070] This invention integrates reaming, honing, dimensional fine-tuning, and fluid supply into a single internal hole machining tool. Utilizing the internal cooling pressure of the machining center as a driving source, it achieves an organic combination of honing pressure establishment, hole diameter adjustment, and cooling and chip removal functions. It allows for continuous reaming and honing of workpiece internal holes on a machining center, offering advantages such as compact structure, convenient adjustment, high machining efficiency, precise dimensional control, and good machining stability. It is particularly suitable for precision machining of high-precision internal holes in difficult-to-machine materials such as titanium alloys. To verify the cooling and chip removal capabilities and machining performance of the tool of this invention, under the same machining conditions, internal hole machining tests were conducted on TB6 titanium alloy internal hole parts, using both the tool of this invention and a control tool without the aforementioned fluid supply structure. During the machining process, a K-type thermocouple was used to monitor the temperature of the workpiece's internal hole wall. The temperature change curve is shown below. Figure 7 As shown. The results indicate that the machining tool of the present invention can effectively reduce the temperature of the inner wall of the workpiece during machining and improve the cooling conditions of the machining area.

[0071] After processing, a pneumatic measuring instrument was used to measure the workpiece hole diameter before and after processing, and the material removal rate was calculated based on the change in hole diameter. The results are as follows. Figure 8 As shown, the material removal rate of the tool of this invention is approximately 2.5 times that of the comparative tool. The above results indicate that this invention, through its fluid supply and guiding structure, delivers pressurized fluid to the machining area of ​​the workpiece's inner hole and the working surface of the honing stone 44. This enhances the cooling, flushing, and chip removal effects of the machining area, reduces the adhesion and clogging of grinding chips on the working surface of the honing stone 44, and maintains the honing stone 44 in a good cutting state, thereby improving material removal capacity and honing stability.

Claims

1. An integrated precision machining tool for reaming and honing internal holes in difficult-to-machine materials, characterized in that, It includes a tool holder (1), a tool bar (2), a reaming assembly (3), a honing assembly (4), a honing dimension fine-tuning mechanism (5), and a liquid supply and guiding structure; The tool holder (1) is located at the rear end of the tool bar (2) and connected to the spindle of the machining center. A pressure fluid channel is provided inside the tool bar (2). The reaming assembly (3) and the honing assembly are arranged sequentially at the front end of the tool holder (2) along the tool axis. The reaming assembly (3) is located in front of the honing assembly (4) along the tool feed direction. The machining tool completes the reaming and honing of the workpiece inner hole in one clamping or one feed process. The reaming assembly (3) includes a reaming insert (31) and a reaming seat (33) for positioning and mounting the reaming insert (31). The reaming insert (31) is disposed on the outer periphery of the reaming seat (33) and is used for reaming the inner hole of the workpiece. The honing assembly (4) includes a piston (41), a tapered rod (43), an oilstone (44), and an oilstone seat (45). The piston (41) is located in the piston chamber (61), which is connected to the pressure fluid channel inside the tool holder (2). After the pressure fluid enters the piston chamber (61), it acts on the pressure end face of the piston (41) and drives the piston (41) to move along the tool axis. The hollow screw (42) connects the piston (41) and the tapered rod (43) and transmits the axial movement of the piston (41) to the tapered rod (43). A tapered surface fit is formed between the tapered rod (43) and the oilstone seat (45). The oilstone (44) is installed on the outside of the oilstone seat (45). The axial movement of the tapered rod (43) is converted into the radial expansion movement of the oilstone seat (45) through the tapered surface fit, which drives the oilstone (44) to extend radially and hones the inner hole of the workpiece. The honing dimension fine adjustment mechanism (5) includes a fine adjustment screw (51) and a fine adjustment limit block (52). The fine adjustment limit block (52) is located at the axial movement termination position of the tapered rod (43). The fine adjustment screw (51) and the fine adjustment limit block (52) are connected in a transmission manner. The fine adjustment limit block (52) moves only along the tool axis, and its position determines the maximum axial working stroke of the tapered rod (43). The fluid supply and guiding structure includes a piston chamber (61), a bypass guiding channel (62), a cone rod center channel (63), a first spray outlet (64), and a second spray outlet (65). The first spray outlet (64) is located on the side of the cone rod (43) center channel, facing the workpiece inner hole wall machining area. The second spray outlet (65) is located in the bypass guiding channel (62), facing the surface of the whetstone (44). After the pressurized fluid enters the piston chamber (61), it acts on the pressurized end face of the piston (41), driving the piston (41) to move along the tool axis. Part of the pressurized fluid enters the cone rod center channel (63) through the hollow screw (42) and is sprayed out from the first spray outlet (64) to cool, flush, and remove chips from the workpiece inner hole wall machining area. Another part of the pressurized fluid flows to the second spray outlet (65) through the bypass guiding channel (62) and is sprayed out from the second spray outlet (65) to remove the grinding chips attached to the surface of the whetstone (44).

2. The integrated precision machining tool for reaming and honing inner holes of difficult-to-machine materials according to claim 1, characterized in that, The reaming assembly (3) also includes a positioning pin (32) and a fixing bolt (34). The reaming seat (33) is provided with a blade mounting part. The reaming blade (31) is positioned on the reaming seat (33) by the positioning pin (32) and fixed by the fixing bolt (34).

3. The integrated precision machining tool for reaming and honing difficult-to-machine materials according to claim 1, characterized in that, The fine-tuning screw (51) has a first threaded section (511) and a second threaded section (512). The first threaded section (511) is threadedly engaged with the reamer seat (33), and the second threaded section (512) is threadedly engaged with the fine-tuning limit block (52). The first threaded section and the second threaded section have the same direction of rotation and different pitches. The pitch of the first threaded section is greater than that of the second threaded section. This pitch difference constitutes a differential thread transmission. When the fine-tuning screw (51) is rotated, the fine-tuning limit block (52) generates a differential displacement relative to the reamer seat (33) along the tool axis determined by the pitch difference, thereby reducing the axial displacement corresponding to a unit rotation angle and realizing the precise adjustment of the axial position of the fine-tuning limit block (52).

4. The integrated precision machining tool for reaming and honing inner holes of difficult-to-machine materials according to claim 1, characterized in that, The honing dimension fine adjustment mechanism (5) also includes an anti-rotation screw (53), which cooperates with the fine adjustment limit block (52) to restrict the fine adjustment limit block (52) from rotating with the fine adjustment screw (51), so that the fine adjustment limit block (52) moves along the tool axis when the fine adjustment screw (51) rotates.

5. The integrated precision machining tool for reaming and honing inner holes of difficult-to-machine materials according to claim 1, characterized in that, The liquid supply and flow guiding structure also includes a flow guiding screw (66), which is located at the end of the cone rod central channel (63) to block the end of the cone rod central channel (63). The pressure fluid entering the cone rod central channel (63) is preferentially ejected from the first nozzle (64).

6. The integrated precision machining tool for reaming and honing inner holes of difficult-to-machine materials according to claim 1, characterized in that, The tool holder (1) has a tool holder flange (11) at the front end and a tool bar (2) has a tool bar flange (21) at the rear end that cooperates with the tool holder flange (11). A radial adjusting screw (22), an axial adjusting screw (23), and a connecting screw (24) are provided between the tool holder flange (11) and the tool bar flange (21). The connecting screw (24) is used to put the tool holder flange (11) and the tool bar flange (21) in a pre-tight connection state and to lock the tool holder (1) and the tool bar (2) after the runout adjustment is completed. The radial adjusting screw (22) is used to adjust the radial position of the tool bar (2) relative to the tool holder (1) in the pre-tight connection state to adjust the radial runout and coaxiality of the machining tool. The axial adjusting screw (23) is used to adjust the end face posture of the tool bar (2) relative to the tool holder (1) in the pre-tight connection state to adjust the end face runout of the machining tool.

7. The integrated precision machining tool for reaming and honing inner holes of difficult-to-machine materials according to claim 3, characterized in that, Based on the fact that the first thread segment (511) and the second thread segment (512) have the same direction of rotation but different pitches, when the fine-tuning screw (51) rotates, the axial differential displacement Δx of the fine-tuning limit block (52) relative to the reamer seat (33) satisfies the following formula: Δx=(θ / 360°)·|P1-P2| In the formula, Δx is the axial differential displacement of the fine-tuning limit block (52) relative to the reaming seat (33), θ is the rotation angle of the fine-tuning screw (51), P1 is the pitch of the first thread segment (511), and P2 is the pitch of the second thread segment (512).

8. The integrated precision machining tool for reaming and honing inner holes of difficult-to-machine materials according to claim 7, characterized in that, The axial displacement of the tapered rod (43) is converted into the radial expansion displacement of the oilstone (44) via the tapered surface transmission. The theoretical aperture increment ΔD corresponding to the radial expansion of the oilstone (44) satisfies the following equation: In the formula, ΔD is the theoretical pore size increment corresponding to the radial expansion of the oilstone (44). θ is the radial expansion of the whetstone on one side, θ is the rotation angle of the fine-tuning screw (51), P1 is the pitch of the first thread segment (511), P2 is the pitch of the second thread segment (512), and α is the half cone angle of the mating cone surface of the cone rod (43) and the whetstone seat (45).

9. A method of using the integrated precision machining tool for reaming and honing difficult-to-machine materials as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Install the machining tool on the spindle of the machining center through the tool holder (1), and use the connecting screw (24) to make the flange part (11) of the tool holder and the flange part (21) of the tool bar in a pre-tight connection state; then adjust the radial adjustment screw (22) to make the radial position of the tool bar (2) relative to the tool holder (1) meet the coaxiality requirements; then adjust the axial adjustment screw (23) to make the end face runout of the machining tool meet the machining requirements; (2) Adjust the honing dimension fine adjustment mechanism (5) according to the target size of the hole to be processed, and determine the axial limit position of the cone rod (43); (3) Start the machining program and turn on the pressure fluid supply. The pressure fluid enters the piston chamber (61) and acts on the pressure end face of the piston (41), pushing the piston (41) to drive the cone rod (43) to move along the tool axis, causing the oilstone seat (45) and oilstone (44) to expand radially. (4) The cutting tool feeds along the inner hole of the workpiece, the reaming assembly (3) first reams the inner hole of the workpiece, and the honing assembly (4) then hones the inner hole surface after reaming. (5) During the processing, the pressure fluid is ejected from the first nozzle (64) through the central channel (63) of the cone rod to cool, flush and remove chips from the processing area of ​​the inner hole wall of the workpiece; the pressure fluid is ejected from the second nozzle (65) through the bypass guide channel (62) to flush the grinding chips attached to the surface of the oilstone (44). (6) After the machining is completed, stop the supply of pressure fluid, so that the oilstone (44) is radially retracted and removed from the inner wall of the workpiece. Then, the machining tool is withdrawn from the inner hole of the workpiece to prevent scratching the inner hole surface of the workpiece during the withdrawal process.

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