Machining methods for complex-shaped deep groove-quenched hardware of large-diameter deep blind hole alloy structural steel.

Abstract

This invention relates to a method for machining complex-shaped deep-groove hardened parts made of alloy structural steel with large-diameter deep blind holes. It utilizes various specialized tools and fixtures in different processes to address the problems of high machining accuracy, long cycle times, high costs, and the tendency for parts to be scrapped. The method employs a large-diameter deep-hole adjustable U-drill, a large-diameter deep-hole flat-bottom drill, a CNC vibration-damping tool holder specifically designed for deep blind hole double-head endoscopes, a rapid indexing device, and a specialized internal cooling quenching device to solve the machining challenges of complex-shaped deep-groove hardened parts made of alloy structural steel with large-diameter deep holes. After machining, the roundness of the deep hole is ≤0.015mm, and the symmetry of the six equally divided grooves is ≤0.03mm, fully meeting the technical requirements of high-precision complex parts.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to a machining method for complex-shaped deep-groove quenched hardware of large-diameter deep blind hole alloy structural steel, which is particularly suitable for machining high-precision complex workpieces made of 35CrMnSiA material with a hardness of HRC48~52 after heat treatment. Background Technology

[0002] For large-diameter, deep-blind-hole alloy structural steel with complex shapes and deep grooves made of 35CrMnSiA, the mechanical properties of the material after heat treatment are: tensile strength greater than 1600MPa, yield strength greater than 1200MPa, and hardness HRC48~52. The workpiece has a deep blind hole at its center, six equally distributed deep grooves, and six interconnected arc surfaces on its circumference.

[0003] Currently, for machining complex-shaped deep-groove hardened alloy structural steel parts, single-piece and small-batch processing typically involves turning and milling to the finished size. However, the workpieces have complex shapes, high precision requirements, and high hardness (HRC48-52). Machining deep grooves and complex surfaces after hardening results in high tool consumption and costs. If deep grooves are rough-milled before hardening, the finishing turning of deep holes and outer diameters after hardening is intermittent, making tool tip chipping easy and compromising the quality of deep blind holes. Conversely, if deep grooves are not rough-milled before hardening, the machining allowance after hardening is large, leading to long machining time and high costs at the machining center, posing significant challenges to the machining process.

[0004] Traditional processing methods have the following problems:

[0005] 1. Difficult machining after quenching: High hardness leads to severe tool wear, easy chipping of the tool tip, and difficulty in ensuring the quality of deep blind holes.

[0006] 2. Low processing efficiency: After rough milling the deep groove before quenching, the quenching deformation requires a large precision machining allowance, resulting in a long processing cycle.

[0007] 3. Insufficient precision: The form and position tolerances of the equally distributed deep grooves and the connection of the arc surfaces are difficult to control. Summary of the Invention

[0008] This invention provides a method for processing complex-shaped deep-groove quenched hardware of alloy structural steel. The technical problem to be solved is: to address the issues of high processing accuracy, long production cycle, high manufacturing cost, and easy scrapping of large-diameter deep blind hole alloy structural steel complex-shaped deep-groove quenched hardware.

[0009] To address the above technical problems, this invention provides a method for processing complex-shaped deep-groove quenched alloy structural steel components, characterized by the following steps:

[0010] S1. Blanking: Select 35CrMnSiA round steel. The diameter of the raw material is 10 mm larger than the finished size of the workpiece. Leave a 10 mm machining allowance for the entire length and perform non-destructive testing.

[0011] S2. Rough turning of outer diameter: Clamp and support the blank to rough turn the outer diameter, leaving a 3mm to 4mm allowance for each outer diameter and a 1mm to 2mm allowance for the step length. After adjusting the center support to support the workpiece, turn the end face.

[0012] S3. Turn around and clamp: Turn around and clamp the workpiece to turn the other end face, and control the allowance of the workpiece length to be 3mm to 4mm.

[0013] S4. Deep Hole Drilling: Use a drill-reamer integrated deep hole drill to drill deep holes, leaving a 3mm finishing allowance for the hole diameter. Then, use a flat bottom drill to machine the bottom surface of the hole to be 0.5mm smaller than the hole depth. Use a special tool holder to fix the tool and adjust the tool axis to coincide with the machine tool spindle axis using a height gauge and a magnetic meter.

[0014] S5. Quenching: Heat the workpiece to 880℃ and hold for 3 to 3.5 hours. Use a special internal spray quenching device for oil quenching. Tempering temperature is 350℃ to 400℃. After the hardness is tested and found to be qualified, proceed to finishing.

[0015] S6. Semi-finished outer diameter: Clamped with a three-jaw chuck and a fan-shaped center, the semi-finished outer diameter allowance is 2mm to 3mm to ensure that the circular runout is ≤0.02mm;

[0016] S7. Finishing the right end face and deep blind hole: Use a four-jaw chuck and center rest for clamping. Use a double-headed multi-purpose tool to complete the threaded bottom hole, the inner hole of the stop and the thread. Use a double-tip special tool to turn the inner end face of the deep hole to ensure flatness.

[0017] S8. Finish machining of the left end face and left blind hole: Use the same clamping method as S7 to turn the left end face and inner hole;

[0018] S9. Machining the wire-threading hole: Mill an equally spaced platform on a machining center and drill a φ20 wire-threading hole;

[0019] S10, wire EDM deep groove and outer arc: The workpiece is clamped using a high-precision indexing plate and threaded positioning shaft. The six-divided deep groove and outer arc groove are machined by wire EDM. The inner hole is filled with cutting fluid to enhance chip removal.

[0020] S11. Precision milling of arc grooves and holes: Precision milling of six equally divided arc grooves on a vertical machining center to complete the final machining of each hole and groove.

[0021] Beneficial effects: This invention optimizes the hardware process route for deep groove quenching of complex-shaped alloy structural steel, adopting a step-by-step processing strategy of "rough turning → deep hole pre-machining → quenching → semi-finishing → finish machining → wire cutting → finish milling" to reduce the impact of quenching deformation.

[0022] Using a variety of specialized tools and fixtures in different processes, we can solve the problems of high machining accuracy, long cycle time, high cost, and easy scrapping of parts caused by complex shapes of deep groove quenching hardware for large-diameter deep blind hole alloy structural steel.

[0023] Utilizing an integrated deep-hole drill and reamer, a large-hole deep-hole flat-bottom drill, a CNC vibration-damping tool holder for deep blind holes with double-head endoscopes, a rapid indexing device, and a dedicated internal cooling quenching device to enhance rigidity, the internal spray quenching furnace body, in conjunction with a dedicated lifting fixture, achieves rapid and uniform cooling. A high-precision vertical / horizontal conversion indexing plate combined with an adjustable center high tailstock ensures the machining accuracy of six equally divided deep grooves and arcs. This solves the hardware challenges of machining complex-shaped deep grooves in large-diameter deep-hole alloy structural steel.

[0024] Tool life is increased by 30%, and machining cycle time is shortened by 40%. The roundness error of deep blind holes is ≤0.02mm, and the indexing accuracy of six-part deep grooves is ≤±5′. Attached Figure Description

[0025] Figure 1 Schematic diagram of the blank after material preparation

[0026] Figure 2 Schematic diagram of the part after rough machining

[0027] Figure 3 Deep hole clamping diagram

[0028] Figure 4 Schematic diagram of preliminary drilling of deep hole

[0029] Figure 5 Schematic diagram of drilling and reaming integrated deep hole drilling tools and tool holders

[0030] Figure 6 Schematic diagram of completed flat bottom processing

[0031] Figure 7 Flat-bottomed knife diagram

[0032] Figure 8 Assembly diagram of internal spray quenching device

[0033] Figure 9 Schematic diagram of internal spray-quenched workpiece lifting fixture

[0034] Figure 10 Schematic diagram of internal spray quenching furnace body

[0035] Figure 11 Schematic diagram of thread, stop, and hollow groove machining

[0036] Figure 12 Schematic diagram of tools and tool holders for threading, stop, and hollow groove machining.

[0037] Figure 13Schematic diagram of precision machining of inner bore and flattened deep bore end face

[0038] Figure 14 Schematic diagram of tools and tool holders for precision turning of inner holes and flattening deep holes.

[0039] Figure 15 Schematic diagram of wire threading hole in machining center

[0040] Figure 16 Schematic diagram of the part after slotting.

[0041] Figure 17 Schematic diagram of clamping for machining a six-part circular arc

[0042] Figure 18 Schematic diagram of the part after machining the six equal parts of the circular arc.

[0043] Figure 19 Schematic diagram of finished parts

[0044] Figure 20 Schematic diagram of special knife clip

[0045] Figure 21 3D view of the internal spray quenching furnace body. Detailed Implementation

[0046] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below.

[0047] The present invention proposes a processing method for complex-shaped deep groove quenching hardware of alloy structural steel, wherein the quenching hardware has a deep blind hole at its center, six deep grooves are evenly distributed, and six circular arc surfaces are connected on the circumference.

[0048] Specifically, the processing steps include the following:

[0049] S1. Material preparation: 35CrMnSiA round steel (GB / T3077-2015) is selected, and 100% of the raw materials undergo non-destructive testing.

[0050] The selected material diameter is 10 mm larger than the finished workpiece size, with a 10 mm machining allowance along the entire length. Figure 1 As shown. Non-destructive testing: Ensures that the material is free of internal defects such as cracks and pores.

[0051] S2. Rough turning of outer diameter and end face: Clamp and support the prepared "blank 1" to rough turn the outer diameter, leaving a 3mm-4mm allowance for each outer diameter and a 1mm-2mm allowance for the length of each outer diameter step to ensure the finishing allowance after quenching. Figure 2As shown. With the workpiece stationary, place a long shim on the machine tool guide rail, and then place an adjustable V-block on the shim to support the workpiece. Remove the center. Install the center rest, move the center in to tighten the workpiece, and remove the long shim and adjustable V-block. Adjust the center rest support jaws to support the workpiece, and then machine the workpiece end face until it is smooth.

[0052] Adjustable V-block: Placed on the long pad of the machine tool guide rail, it supports the workpiece during rough turning and avoids vibration.

[0053] S3. Turning and clamping: Clamp one and support one, turn the workpiece around and clamp it to turn the other end face, and control the workpiece to leave a 3mm to 4mm allowance for finishing after quenching.

[0054] S4. Deep hole pre-machining: Use a chuck and a top to drill deep holes using an integrated drill and reamer, and then use a flat bottom drill to machine the bottom plane of the deep hole.

[0055] This integrated drilling and reaming deep hole drill includes:

[0056] The main body of the integrated drilling and reaming deep hole drill includes: centering drill 4, drainage hole 5, blade support 6, blade 7, blade locking bolt 8, locking bolt 9, blade body 10, slot 11, and sealing groove 12;

[0057] The insert holder is fixed to the front of the tool body by locking bolts. The inserts are fixed to the insert holder by insert locking bolts. The four inserts 7 are fixed at 180° angles to both sides of the tool body 10 by locking bolts. After rotating 180°, the two inserts on one side are staggered relative to the two inserts on the other side. This structure ensures that the area that one side cannot machine can be machined by the other side when using a standard CNC tool head, thus enabling large-diameter drilling. The multi-insert design also extends the overall tool life. The design with the inserts distributed on both sides makes the cutting force more stable relative to the tool body. The selected polygonal tool has strong cutting resistance, and the annular V-groove formed by cutting ensures that the tool tip position is always within the annular V-groove, increasing the stability of the insert and improving chip removal. The centering drill 4 is fixed to the center of the front end of the tool body by locking bolts. According to the workpiece processing requirements, the extension length of the centering drill can be adjusted by adjusting the locking bolt, and different angle centering drills can be replaced. This design can ensure that the tool is guided by the centering drill during drilling, thereby enhancing the overall stability of the tool and the processing accuracy. The centering drill is divided into two types according to the processing procedure: 120° centering drill bit and 180° centering drill bit, which are used for the front-end centering and the rear-end flat center hole, respectively. Multiple drainage holes 5 are opened along the chip removal groove of the tool body, the centering drill, and the top of the tool body to accelerate the cooling, lubrication, and flushing of the processing position and the tool. The tool body 10 is designed with chip removal grooves along the spiral direction of the centering drill, which can help guide and remove the long spiral chips generated by the centering drill. The end of the tool body is provided with a sealing groove 12, and a sealing ring is embedded in the sealing groove. Under the action of the groove and the clasp 11, the sealing connection with the tool holder is completed, increasing the stability and connection strength of the tool body.

[0058] Tool holder: Composed of a locking block 13, a locking bolt 14, a multi-stage tool holder body 15, and a fixing groove 16. The number of tool holders connected to the multi-stage tool holder body is increased according to the drilling depth. The increased tool holders are connected step by step by locking bolts, and the end is provided with a fixing groove that cooperates with the tool clip.

[0059] Special tool holder: Made of ductile iron in one piece, with good shock absorption. The main body is cylindrical with internal slots (slot width adjustable). Set screws (located on the slotted side of the tool holder to open the slot) and locking bolts (located on the closed side of the tool holder to fix the tool holder) are provided on both sides.

[0060] The tool holder and the tool clip axis coincide, and the tool clip is installed at the front end of the slide plate in the machine tool.

[0061] Insert 7 is a polygonal insert, preferably WCGX06T308-Z HT01 10PCS inserts. The centering drill is an HPD-2556C-H centering drill.

[0062] Leave a 3mm machining allowance for the deep hole diameter after quenching. The shank of the integrated drill and reamer needs to be clamped on a special tool holder, which is fixed to the machine tool slide with six locking bolts (83). The special tool holder is made of ductile iron and fits snugly with the tool shank of the integrated drill and reamer, providing high strength and good vibration resistance. After inserting the tool shank into the slotted hole of the tool holder, loosen the set screw and tighten the locking bolts to clamp the tool shank.

[0063] The three special tools used in subsequent processing are all fixed with this special tool holder. The special tool holder is opened by two set screws 80 on one side of the slot, and the tool shank is locked to the tool holder body 82 by four locking bolts 81. The tool holder is as follows. Figure 20 As shown. A height gauge and magnetic meter were used to align, check, and adjust the drill bit to ensure its axis coincides with the machine tool spindle axis. Figure 3 As shown.

[0064] Machining steps: Adjust the lathe cutting parameters to 100 rpm and 0.2 mm / rpm. Use the center drill of the integrated drill and reamer to drill to a depth 1-2 mm less than the hole depth. Figure 4 , 5 As shown. Adjust the locking bolts of the integrated drilling and reaming deep hole centering drill, remove the 120° centering drill bit, and replace it with a 180° centering drill bit to level the center hole.

[0065] When drilling a flat bottom, ensure timely chip removal to maintain cutting stability. Carefully observe cooling and chip removal to guarantee a smooth drilling process. Flatten the bottom to be 0.5mm less than the hole depth. Figure 6 , 7 As shown.

[0066] The flat bottom drill consists of a first blade 18, a second blade 19, a blade locking bolt 20, a shock-absorbing and centering guide block 21, a locking bolt 22, a drill body 23, a drain hole 24, a slot 25, a locking hole 26, and a sealing groove 27. The drill bar used consists of a slot block 28, a locking bolt 29, a drill bar body 30, and a fixing groove 31.

[0067] The first insert 18 and the second insert 19 are fixed to the tool body by insert locking bolts. One side of the tool body 23 has one first insert 18 and one second insert 19, while the other side has two second inserts 19. The two sides are distributed at a 180° angle to the tool body 23. The first insert 18 is installed on the outer side. After rotating 180°, the two inserts on one side are staggered relative to the two inserts on the other side. This structure, when using a standard CNC tool head, ensures that areas that cannot be machined by one side can be machined by the other side, achieving large-diameter flat bottoms. The multi-insert design also extends the overall tool life. The two-side distribution design provides more stable cutting force relative to the tool body. After installation, the first insert 18 has no back angle in its circumferential arc and does not produce cutting action; it only serves as a guide. The tool body features a back angle on the bottom edge (flat bottom surface), which, together with the other three second cutting tools 19, enables a flat bottom operation without dead angles or enlargement. Multiple drainage holes 24 are distributed longitudinally along the chip removal groove of the tool body to accelerate cooling, lubrication, and rinsing of the machining area and the tool. The rear end of the tool body has a slot 25, a locking hole 26, and a sealing groove 27. A sealing ring is embedded in the sealing groove for sealing connection with the tool holder. Due to the large cutting force generated when drilling a flat bottom, the increased connection of the slot 25, locking hole 26, and tool holder significantly improves the stability and connection strength of the tool body. The shock-absorbing and centering guide block 21, made of cemented carbide, is fixed to the tool body by locking bolts. Its outer diameter relative to the axis of the tool body 23 is slightly smaller than the workpiece hole diameter. By engaging with the inner wall of the workpiece hole, it provides shock absorption, centering, and guidance.

[0068] The first insert 18 uses an APMT160430-DR CP8018 insert, and the second insert 19 uses an SPMT120408-LP30 insert;

[0069] S5. Quenching treatment: Heat the workpiece to 880℃ and hold for 3h~3.5h. Use a special internal spray quenching device for oil quenching. Tempering temperature is 350℃~400℃. After the hardness is tested and found to be qualified, proceed to finishing.

[0070] Due to the large size of the workpiece, it was placed in a stainless steel lifting cage and heated to 880°C in a 1200°C high-temperature pit furnace with high temperature control precision for 3-3.5 hours. Subsequently, a special stainless steel lifting device 32, along with the workpiece 34, was placed into a spray-quenching furnace within an oil bath for quenching. Figure 8 As shown.

[0071] The specialized internal spray quenching device includes a lifting device and an internal spray quenching furnace body. The lifting device facilitates the loading and unloading of workpieces, such as... Figure 9 As shown, the lifting device consists of a lifting ring 35, a cover plate 36, a positioning hole 37, a clamping plate 38, a connecting plate 39, a movable pin 40, a pin shaft 41, and a guide clamp 42.

[0072] The lifting ring 35 is located at the top of the lifting device and is fixedly connected to the cover plate. It is used vertically to connect to the crane hook.

[0073] The cover plate 36 and the connecting plate 39 are arranged in parallel, forming a horizontal clamping space between them, which is used to bear half of the bottom step of the blind hole of the workpiece and half of the workpiece's weight.

[0074] The clamping plate 38 is located between the cover plate 36 and the connecting plate 39. When closed, its two sides contact the stepped side of the workpiece, which serves to guide the workpiece and provide clamping force.

[0075] The alignment clamp 42 is located at the entrance end of the clamping space. Three guide plates below it match the outer contour of the workpiece step, ensuring automatic alignment during workpiece insertion. One end of the alignment clamp 42 is hinged to the connecting plate 39 via a pin 41, and the other end is fixed to the connecting plate 39 via a movable pin 40. After closing, the movable pin 40 is inserted, and the upper end face of the alignment clamp bears the weight of the bottom step of the other half of the blind hole. One alignment clamp 42 is connected to each end of the connecting plate 39.

[0076] The positioning hole 37 has a positioning pin inserted inside, which serves to position the cover plate 36, clamping plate 38, and connecting plate 39 during welding.

[0077] When in use, remove the movable pin 40, open the centering clamp 42, insert the step on one side of the bottom of the blind hole of the workpiece into the middle of the cover plate 36 and the connecting plate 39, close the centering clamp 42, insert the movable pin 40, hook the crane hook into the lifting ring 35, start the crane to lift, and realize the lifting of two workpieces at one time.

[0078] Because the workpiece has a blind hole structure at one end, a special internal spray quenching furnace is placed inside the oil tank to improve the overall quenching effect. Figure 10 As shown, it consists of a lifting ring 43, a guide ring 44, a flow hole 45, an oil supply pipe 46, an oil injector 47, and a furnace frame 48.

[0079] The guide ring 44 is fixed to the top opening of the furnace frame 48 by welding. It works in conjunction with the six guide plates at the lower end of the workpiece lifting clamp 42 to enable rapid entry into the furnace under swaying conditions during the lifting operation. At the same time, it plays a role in concentric positioning of the workpiece opening side and the oil nozzle 47, ensuring the concentricity of the workpiece and the oil nozzle 47.

[0080] The nozzle 47 is installed at the end of the oil pipe 46 by a variable diameter welding method. During operation, the nozzle 47 covers the end of the workpiece with an opening, and the nozzle 47 sprays oil upward to expel the air from the blind hole.

[0081] The main section of the oil supply pipe 46 passes through the furnace frame 48 and is welded and fixed. It is connected to the external oil pump supply pipe through a flange. The oil pump inlet is connected to the oil tank to form a closed-loop quenching oil circulation system.

[0082] The flow hole 45 is directly opened on the side wall of the furnace frame 48. The quenching oil inside the furnace flows into the oil tank through the flow hole 45, realizing the efficient circulation of quenching oil.

[0083] The lifting ring 43 is welded to the top of the furnace frame 48 and is used to connect with the crane hook when installing and disassembling the internal spray quenching furnace body in the oil tank, so as to facilitate the movement and adjustment of the furnace body.

[0084] After the overhead crane lifts the workpiece using a special stainless steel lifting tool, it is then positioned over the oil nozzle by the combined alignment clamp 42 and guide ring 44. The furnace body has good cooling properties, ensuring sufficient quenching depth. The tempering temperature is 350℃~400℃. Hardness is tested using a high-precision portable Rockwell hardness tester, and samples are taken from the furnace for further testing. After the performance parameters are deemed satisfactory, the workpiece undergoes quenching followed by precision machining.

[0085] Through the precise matching of the guide ring and the lifting device, the layout design of the oil nozzle, and the efficient oil circuit design, the quenching furnace body significantly improves the quenching depth and cooling uniformity, and solves the problems of deformation and uneven hardness of large-sized quenched hardware.

[0086] S6, Semi-finished outer diameter

[0087] After quenching, the workpiece is supported by a three-jaw chuck at one end and a fan-shaped center at the other. The semi-finished outer diameter allowance is 2mm to 3mm. All outer diameter dimensions are completed in one clamping and are tested with a magnetic gauge. The circular runout of each outer diameter is within 0.02mm, ensuring the datum roundness and circular runout accuracy of the outer diameter, and ensuring the dimensional and positional accuracy of each inner hole in the finishing process.

[0088] S7. Finishing the right end face, deep blind hole threaded hole, and stepped hole: Use a four-jaw chuck and center rest for clamping. Use a double-headed multi-purpose tool to complete the threaded bottom hole, stop inner hole and thread machining. Use a double-tip special tool and an endoscope vibration damping tool holder to turn the inner end face of the deep hole to ensure flatness.

[0089] A high-precision CNC lathe is used, with a one-jaw-one-rest clamping method using a four-jaw chuck and a center rest. The workpiece is clamped with the four-jaw chuck, and two magnetic gauges are placed near the chuck and tailstock end of the workpiece to align it. When the pointers of the magnetic gauges at the two points jump within 0.03mm, the center rest supports the jaws to contact and support the workpiece. The support force should be appropriate, neither too large nor too small.

[0090] Install a multi-purpose tool with both positive and negative cutting heads, and complete thread drilling, including the preparation of the pilot hole, the inner hole of the stop, and thread machining. Figure 11 ,12 As shown. Because the thread cutting tool tip faces downwards, the tool can move to the opposite side to cut the thread without changing the lathe's rotational speed. This tool saves time on tool changeover and clamping.

[0091] The dual-head multi-purpose knife consists of an internal threaded insert 49, a finishing insert 50, a knife body 51, an insert locking bolt 52, a locking bolt 53, a drain hole 54, and meshing threads 55.

[0092] The finishing insert 50 uses CNMG 12 04 08-PM 4415 inserts;

[0093] The finishing insert 50 and the internal threading insert 49 are fixed at 180° to both sides of the tool body 51 by insert locking bolts 52. The internal threading insert is located on the left side of the front end of the tool body, and the finishing insert is located on the right side. The spindle moves in the positive and negative X-axis directions of the CNC machine tool to respectively correspond to the finishing of the inner end face of the deep hole and subsequent threading. Multiple drainage holes 54 are provided along the chip removal groove of the tool body to accelerate the cooling, lubrication and flushing of the machining position and the tool. The bottom of the tool body 51 is provided with meshing threads 55 that cooperate with the end of the endoscope vibration damping tool holder. The axial and radial stable high-strength connection with the tool holder is achieved through the meshing action of the meshing threads and the locking bolts.

[0094] The endoscope vibration damping tool bar consists of meshing threads 55, locking bolts 56, a wide-angle wired camera module 57, a supplementary light 58, a wide-angle camera 59, and a wire groove 60. The wide-angle wired camera module is located on the front side of the tool bar and is fixed to the tool bar by locking bolts. Considering that the supplementary light 58 and the wide-angle camera 59 may be easily damaged during processing, they are designed as quick-connect structures to be inserted into the wide-angle wired camera module 57. The wired camera module 57 is the mainboard, used for power supply and signal transmission, etc. The tool bar body is hollow inside and has a drain hole 54. The surface of the tool bar body has a wire groove 60 for wiring of the wide-angle wired camera module. The front end of the tool bar has meshing threads that cooperate with the meshing threads at the end of the tool body 51.

[0095] The meshing threads of the double-headed multi-purpose tool are pressed into the meshing threads at the front end of the tool holder and fixed by locking bolts; the camera module is connected to an external display or mobile terminal through a wire groove to realize the function of real-time monitoring of the turning status.

[0096] Because the deep blind hole has a large diameter and a tolerance requirement for its depth, the inner bottom surface 61 needs to be machined when turning the deep blind hole. To increase the rigidity of the tool holder, a vibration-damping tool holder and a special tool holder are required. They are fixed to the lathe support plate with bolts 83. The special tool holder slotted tool holder mounting hole is opened with set screws 80. The clearance between the tool holder mounting hole and the tool holder is 0.02mm to 0.04mm. The endoscope vibration-damping tool holder is installed on the special tool holder slotted tool holder mounting hole. The length of the tool holder extending out of the tool holder is 2mm to 4mm greater than the depth of the deep hole of the workpiece. The set screws are loosened and the locking bolts are tightened.

[0097] Because the length-to-diameter ratio of the workpiece hole reaches 10 times the diameter, the cross-sectional area of ​​the tool holder should be maximized to increase its rigidity. The distance between the outer diameter of the tool holder and the inner wall of the deep hole is less than the distance between the tip of the standard tool and the center of the workpiece on the inner end face of the deep hole. A double-tip tool for turning deep holes and their inner end faces is clamped on the endoscope vibration-damping tool holder. The workpiece end face is faced with the tool, and the tool holder position is slightly adjusted so that both tips of the double-tip tool simultaneously contact the workpiece end face. The first tip of the double-tip tool is used to turn the inner hole and half the distance from the inner end face to the center of the inner end face at the diameter of the deep hole. The second tip is used to turn half the distance from the inner end face of the deep hole to the center of the workpiece, ensuring the flatness of the turned inner end face of the deep hole.

[0098] like Figure 13 , 14 As shown, the dual-blade special blade consists of a blade 62, a blade locking bolt 63, a blade body 64, a locking bolt 65, a drain hole 66, and a meshing thread 67. The endoscope vibration damping blade rod consists of a drain hole 66, a meshing thread 67, a locking bolt 68, a wide-angle wired camera module 69, a supplementary light 70, a wide-angle camera 71, and a wire groove 72.

[0099] The blade 62 uses VBMT 16 04 08-PM 4415 blades;

[0100] There are two blades 62, with their cutting edges in the same plane. They are locked to one side of the tool body 64 by blade locking bolts 63. The double-blade design can avoid the situation where the tool cannot machine some inner end faces due to interference between the tool holder and the inner wall of the workpiece during the movement of the tool holder and the tool, thus increasing the machining efficiency. Two drainage holes 66 are provided at the bottom of the blade to accelerate the cooling, lubrication and flushing of the machining position and the tool. The bottom of the tool body 64 is provided with meshing threads 67 that cooperate with the end of the endoscope vibration damping tool holder. The axial and radial stable high-strength connection with the tool holder is achieved through the meshing action of the meshing threads and the locking bolt.

[0101] The endoscope vibration damping tool bar consists of a drain hole 66, meshing threads 67, a locking bolt 68, a wide-angle wired camera module 69, a supplementary light 70, a wide-angle camera 71, and a wire groove 72. The wide-angle wired camera module is located on the front side of the tool bar and is fixed to the tool bar by the locking bolt. Considering that the supplementary light 70 and the wide-angle camera 69 may be easily damaged during processing, they are designed with a quick-connect structure to be inserted into the wide-angle wired camera module 69. The wired camera module 69 is the mainboard, used for power supply and signal transmission, etc. The tool bar body is hollow inside and has a drain hole 66. The surface of the tool bar body has a wire groove 72 for wiring of the wide-angle wired camera module. The front end of the tool bar has meshing threads that cooperate with the meshing threads at the end of the tool body 64.

[0102] The meshing threads of the double-headed multi-purpose tool are pressed into the meshing threads at the front end of the tool holder and fixed by locking bolts; the camera module is connected to an external display or mobile terminal through a wire groove to realize the function of real-time monitoring of the turning status.

[0103] Loosen the tool holder locking bolt, adjust the length of the vibration damping tool holder extending from the tool holder, and turn the stepped hole and threaded bottom hole at the step.

[0104] S8. Finish machining the left end face and control the entire length of the workpiece; turn the left end blind hole. Use the same clamping method as S7 to turn the left end face and inner hole;

[0105] A high-precision CNC lathe is used, employing a one-jaw-one-rest clamping method with a four-jaw chuck and a center rest. The workpiece is clamped in the four-jaw chuck, and two magnetic gauges are placed near the chuck and tailstock to align the workpiece. When the magnetic gauge pointers at the two points fluctuate within 0.03mm, the center rest supports the workpiece with appropriate jaws, ensuring the support force is neither too high nor too low. A special mechanically clamped tool head is then used on a vibration-damping tool holder to control the turning of the workpiece's entire length, inner hole, and inner end face.

[0106] S9. Machining the wire-threading hole: Mill an equally spaced platform on a machining center and drill a φ20 wire-threading hole;

[0107] Clamp the workpiece on the fourth-axis chuck of the machining center, ensuring the runout of the outer diameter at both ends of the workpiece is less than 0.02mm. Mill evenly spaced 6-20×20mm platforms at the center of the workpiece's length and circumference, and drill φ20 holes that penetrate the center hole. These holes will serve as wire insertion holes for wire EDM and drainage holes for water-based EDM. Figure 15 As shown.

[0108] S10, Wire EDM Deep Groove and Outer Circle Arc Groove: Use a high-precision indexing plate and threaded positioning shaft to clamp the workpiece, process a six-division deep groove by wire EDM, and then use an adjustable support fixture for the outer circle arc divided into six divisions to clamp the workpiece and process the outer circle arc groove divided into six divisions.

[0109] A high-precision indexing plate is installed on the wire EDM machine guide rail. The workpiece support plate is bolted to the wire EDM machine guide rail and the convertible indexing plate to enhance the strength and rigidity of the indexing plate in horizontal use. An adjustable center high tailstock is installed on the wire EDM fixture base and connected to the machine guide rail. A threaded positioning shaft is fabricated, using the workpiece thread and stop as the positioning shaft. The shaft-hole fit clearance is 0.03mm to 0.05mm. The center hole of the threaded positioning shaft fits with the outer diameter of the Morse No. 2 center of the adjustable center seat, with a clearance of 0.02mm to 0.03mm. A magnetic gauge is attached to the wire EDM machine guide rail. The dial indicator's measuring rod contactes the outer circle of the convertible indexing plate chuck. The high-precision vertical-horizontal convertible indexing plate is rotated, and the dial indicator pointer swing range is observed. When the runout of the chuck's outer circle is less than 0.02mm, all locking nuts are tightened. Multiple checks are performed to ensure workpiece positioning and clamping accuracy.

[0110] The workpiece is hoisted onto the chuck of the high-precision vertical-horizontal conversion indexing plate. A magnetic dial indicator is used to align both ends of the workpiece within 0.02mm. The threaded and stop surfaces of the workpiece should face the adjustable center high tailstock. The threaded locating shaft is screwed onto the workpiece, and the center shaft of the adjustable center high tailstock is moved into the center hole of the threaded locating shaft. The shaft-hole clearance is controlled between 0.02mm and 0.03mm. The lock nut is tightened to provide positioning and support. The coaxiality of the workpiece is then recalibrated using a magnetic dial indicator to within 0.02mm.

[0111] Adjust the high-precision vertical / horizontal conversion indexing plate and machine tool guideways to align the center position of the φ20 wire threading hole. Complete the wire feeding, tightening, and threading operations, and adjust the machine tool and program line for symmetrical deep groove cutting. Use a T-junction to branch off a separate water pipe from the machine tool's water tank, inserting it into the φ20 wire threading hole at a 60° angle to the upper wire threading hole. This enhances chip removal after the molybdenum wire discharges. After the molybdenum wire has cut 5mm beyond the φ20 hole, pause cutting. Plug the remaining four wire threading holes (excluding the water supply pipe and the upper hole) with wooden or cloth plugs to ensure the cutting fluid fills the workpiece's inner hole, allowing the molybdenum wire to fully immerse itself in the cutting fluid for electro-cutting, enhancing chip removal and improving processing efficiency. Set a pause point 3mm-5mm from the completion of the deep groove machining. Secure both ends of the deep groove with clamps to prevent the cut lower key-shaped metal from falling. Use a strong magnetic chuck to hold the cut upper key-shaped metal from above and prevent it from falling. Loosen the clamps and remove the lower key-shaped metal. Use a long T-bolt to support the upper key-shaped metal that has been cut. Loosen the magnetic chuck to lift and remove the upper key-shaped metal. Loosen the molybdenum wire on the wire spool and remove it from the guide wheel. Rotate the high-precision vertical / horizontal conversion indexing plate 60°. Thread the wire through the φ20 process hole on the workpiece and complete the wire threading and tightening work. Adjust the machine tool and program to wire cut symmetrical deep grooves. After the molybdenum wire cuts 5mm from the φ20 hole, pause the cutting. Use key-shaped wooden or cloth plugs to plug the remaining process threading holes and the cut key-shaped deep grooves, except for the water inlet pipe and the upper hole. This allows the cutting fluid to fill the inner hole of the workpiece, ensuring the molybdenum wire is fully immersed in the cutting fluid for electro-cutting. This enhances the chip removal effect after the molybdenum wire discharges, improving processing efficiency. Repeat the above actions to complete the wire cutting of the six equally divided deep grooves and remove workpiece 73. Figure 16 As shown.

[0112] On an online cutting machine, an adjustable support fixture with an outer diameter divided into six equal parts is mounted on the machine's guide rail. This fixture consists of a mounting plate 74, a locating key locking bolt 75, a locating key 76, a fixture body 77, a locating plug 78, and an end face bearing 79. Figure 17 As shown.

[0113] The adjustable support fixture for the six-part circular arc is symmetrically distributed from left to right. Its mounting plate 74 and fixture body 77 are integrally machined by a machining center to ensure the accuracy of each hole and the parallelism of the upper and lower planes. The fixture body is fixed on the guide rail of the wire cutting machine. The positioning key 76 is installed in the corresponding hole of the fixture body 77. The lower end face of the end bearing 79 is embedded in the reserved groove at the bottom of the fixture body, and the upper end is embedded in the reserved groove at the bottom of the positioning plug 78. The top diameter of the positioning plug 78 is slightly smaller than the diameter of the deep blind hole of the workpiece. During operation, the deep blind hole side of the workpiece is inserted into the top of the positioning plug 78 and rotated appropriately for alignment. After alignment, the positioning key is pushed into the diagonal deep groove of the workpiece 16 and the locking bolt is tightened to complete the wire feeding, tightening, and threading operations. The program control completes the single arc groove cutting operation of the six-part circular arc groove. The single side of the arc groove leaves a margin of 0.4mm. The above actions are repeated to complete the cutting operation of the six-part circular arc groove in sequence. Figure 18As shown.

[0114] S11. Precision milling of arc grooves and holes: Precision milling of six equally divided arc grooves on a vertical machining center to complete the final machining of each hole and groove;

[0115] The wire-cut workpiece is clamped on the fourth-axis rotary table of the vertical machining center. First, the coaxiality of the two ends of the workpiece's outer diameter is aligned. The fourth axis is finely rotated using a hand-cranked pulse generator. A dial indicator is used to check the parallelism between the deep groove plane and the machine tool spindle. After alignment, using the deep groove as a reference, a workpiece coordinate system is established using a photoelectric edge finder or centering bar. In the manual interface, 60°, 120°, 180°, and 240° are input respectively. A dial indicator is used to check the indexing accuracy of the six-divided deep groove surface and its parallelism with the spindle. After passing the checks, the tools are retrieved and set sequentially. The program is then retrieved to complete the precision milling of the six-divided circular arc groove and the machining of all holes and grooves. The finished part after machining is as follows: Figure 19 As shown.

[0116] This invention utilizes various specialized tools and fixtures at different stages to address the challenges of machining complex-shaped deep-groove-quenched hardware for large-diameter, deep-blind-hole alloy structural steel, which involves high precision, long processing times, high costs, and a high likelihood of part scrapping. It employs integrated drilling and reaming deep-hole drills, large-hole and deep-hole flat-bottom drills, deep blind-hole double-head CNC vibration-damping tool holders specifically designed for endoscopes, rapid indexing devices, and specialized internal cooling and quenching devices to solve the machining difficulties of complex-shaped deep-groove-quenched hardware for large-diameter, deep-hole alloy structural steel.

[0117] After machining, the roundness of the deep hole of the workpiece is ≤0.015mm, and the symmetry of the six equally divided grooves is ≤0.03mm, which fully meets the technical requirements of high-precision complex parts.

[0118] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for machining complex-shaped deep-groove quenched hardware made of large-diameter deep blind-hole alloy structural steel, characterized in that, Includes the following steps: S1. Material cutting: 35CrMnSiA round steel is used. S2. Rough turning of outer diameter: Clamp and lift the blank to rough turn the outer diameter, leaving 3mm to 4mm for each outer diameter and 1mm to 2mm for the step length. S3. Turn around and clamp: Turn around and clamp the workpiece to turn the other end face, and control the allowance of the workpiece length to be 3mm to 4mm. S4. Deep hole drilling: Use a drill and reamer to drill deep holes, leaving a 3mm finishing allowance for the hole diameter, and then use a flat bottom drill to machine the bottom surface of the hole to be 0.5mm smaller than the hole depth. S5. Quenching treatment: After heating the workpiece and holding it at the temperature, oil quenching is performed using an internal spray quenching device. The tempering temperature is 350℃~400℃. After the hardness is tested and found to be qualified, it enters the finishing process. S6. Semi-finished outer diameter: Clamped with a three-jaw chuck and a fan-shaped center, the semi-finished outer diameter allowance is 2mm to 3mm to ensure that the circular runout is ≤0.02mm; S7. Finishing the right end face and deep blind hole: Use a four-jaw chuck and center rest for clamping. Use a double-headed multi-purpose tool to complete the threaded bottom hole, the inner hole of the stop and the thread. Use a double-tip special tool to turn the inner end face of the deep hole to ensure flatness. S8. Finish machining of the left end face and left blind hole: Use the same clamping method as S7 to turn the left end face and inner hole; S9. Mill the equally divided platform on the machining center and drill φ20 wire-passing holes; S10, wire EDM machining of six equal deep grooves and outer circular arc grooves; S11. Precision milling of arc grooves and holes: Precision milling of six equally divided arc grooves on a vertical machining center to complete the final machining of each hole and groove.

2. The processing method according to claim 1, characterized in that: In step S1, alloy structural steel round steel is used. The diameter of the raw material is 10 mm larger than the finished workpiece size, and a 10 mm machining allowance is left for the entire length. Non-destructive testing is also performed.

3. The processing method according to claim 1, characterized in that: In step S5, the workpiece is heated to 880℃ and held for 3 to 3.5 hours.

4. The processing method according to claim 1, characterized in that: In step S4, a deep hole is drilled using an integrated drill and reamer. The integrated drill and reamer is fixed to the slide plate of the machine tool by a special tool holder, and the drill axis is adjusted to coincide with the machine tool spindle axis by a height gauge and a magnetic force gauge.

5. The processing method according to claim 4, characterized in that: The integrated drilling and reaming deep hole drill includes a main body and a tool holder; the main body includes a centering drill, a tool holder, a tool, and a tool body; the tool holder is fixed to the front of the tool body, the tool is fixed on the tool holder, and the centering drill is fixed to the center of the front end of the tool body; four tools are fixed at 180° to both sides of the tool body by locking bolts, and the two tools on one side are rotated 180° and then staggered relative to the two tools on the other side; the rear end of the tool body is connected to the tool holder.

6. The processing method according to claim 5, characterized in that: The tool holder includes a multi-stage tool holder body and a fixing groove. The number of tool holders connected to the multi-stage tool holder body is increased according to the drilling depth. The additional tool holders are connected step by step by locking bolts. The fixing groove is provided at the end of the multi-stage tool holder body.

7. The processing method according to claim 1, characterized in that: Step S4 is as follows: Adjust the lathe cutting parameters to 100 rpm and 0.2 mm / rpm. Drill the center drill of the integrated drilling and reaming deep hole drill to a depth 1-2 mm less than the hole depth. Remove the 120° center drill and replace it with a 180° flat bottom drill to flatten the bottom of the hole to a depth 0.5 mm less than the hole depth.

8. The processing method according to claim 1, characterized in that: In step S5, the internal spray quenching device includes a lifting device and an internal spray quenching furnace body. The lifting device includes a cover plate, a clamping plate, a connecting plate, and a centering clamp. The cover plate and the connecting plate are arranged in parallel, forming a horizontal clamping space between them to accommodate the bottom step of the blind hole of the workpiece. The clamping plate is located between the cover and the connecting plate. When closed, its two sides contact the side of the step of the workpiece to provide clamping force. One end of the centering clamp is hinged to the connecting plate by a pin, and the other end is fixed to the connecting plate by a movable pin. The internal spray quenching furnace body includes a guide ring, an oil nozzle, and a furnace body frame. The oil nozzle is installed inside the furnace body frame and is guided and fixed at the top opening of the furnace body frame. It cooperates with the centering clamp of the workpiece lifting device to make the workpiece and the oil nozzle concentrically positioned.

9. The processing method according to claim 1, characterized in that: In step S7, the first tip of the double-tip special tool is used to turn the inner hole and the distance from the inner end face to the center of the inner end face at the diameter of the deep hole. The second tip is used to turn the distance from the inner end face of the deep hole to the center of the workpiece at half the distance and to ensure the flatness of the inner end face of the deep hole.

10. The processing method according to claim 1, characterized in that: In step S10, a high-precision vertical-horizontal conversion indexing plate is used for positioning. The deep groove and the outer arc groove are divided into six equal parts by molybdenum wire electric discharge cutting, with a single-sided allowance of 0.4mm. The outer arc groove is processed using an adjustable support fixture. The precise positioning of the workpiece is achieved by the matching gap between the positioning key and the deep groove of 0.03mm to 0.05mm.

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