Machining method of large-diameter deep blind hole alloy structural steel complex-shape deep groove quenched hardware

Abstract

The invention relates to a machining method for large-diameter deep-blind-hole alloy structural steel complex-shape deep groove quenched hardware. The problems that the large-diameter deep-blind-hole alloy structural steel complex-shape deep groove quenched hardware is high in machining precision, long in period, high in cost and prone to causing part scrapping are solved by means of various special cutters and clamps in different working procedures. A large-hole and deep-hole adjustable U drill, a large-hole and deep-hole bottoming drill, a numerical control vibration reduction cutter bar special for a deep blind hole double-tool-bit endoscope, a rapid dividing device and a special inner cooling quenching device are used for solving the machining problem of large-diameter deep-hole alloy structural steel complex-shape deep groove quenching hardware. The roundness of a deep hole of a machined workpiece is smaller than or equal to 0.015 mm, the symmetry degree of six-equal-division grooves is smaller than or equal to 0.03 mm, and the technical requirements of high-precision complex parts are completely met.

Description

Technical Field

[0001] The present invention belongs to the technical field of machining, and particularly relates to a machining method for a deep groove hardened part with a complex shape of an alloy structural steel having a large diameter and a deep blind hole, and is particularly suitable for machining high-precision complex workpieces made of 35CrMnSiA material and having a hardness of HRC48-52 after heat treatment. Background Art

[0002] For a deep groove hardened part with a complex shape of an alloy structural steel having a large diameter and a deep blind hole made of 35CrMnSiA material, the mechanical properties of the material after heat treatment are as follows: the tensile strength is greater than 1600 MPa, the yield strength is greater than 1200 MPa, and the hardness is HRC48-52. The center of the workpiece is a deep blind hole, six deep grooves are equally distributed, and six arc-shaped surfaces on the circumference are connected.

[0003] At present, for the machining method of deep groove hardened parts with a complex shape of alloy structural steel, turning and milling are used for single-piece and small-batch machining to the finished size. However, the workpiece has a complex shape, high precision requirements, high hardness (HRC48-52), and deep groove and complex surface machining are carried out after quenching, resulting in large tool consumption and high cost. Before quenching, if the deep groove is rough-milled, the deep hole and outer diameter finish turning after quenching are interrupted machining, and the cutting edge of the tool is prone to chipping, and the quality of the deep blind hole is difficult to guarantee. Before quenching, if the deep groove is not rough-milled, the machining allowance after quenching is large, the cutting time cycle of the machining center is long, and the cost is high, which brings great challenges to machining.

[0004] The traditional machining method has the following problems:

[0005] 1. Difficult machining after quenching: High hardness causes serious tool wear, the cutting edge of the tool is prone to chipping, and the quality of the deep blind hole is difficult to guarantee.

[0006] 2. Low machining efficiency: After rough-milling the deep groove before quenching, the quenching deformation requires a large finishing allowance, and the machining cycle is long.

[0007] 3. Insufficient accuracy: It is difficult to control the geometric tolerance of the equal distribution of the deep grooves and the connection of the arc-shaped surfaces. Summary of the Invention

[0008] The present invention provides a machining method for a deep groove hardened part with a complex shape of an alloy structural steel, and the technical problem to be solved is: to solve the problems of high machining precision, long production cycle, high manufacturing cost, and easy part scrapping of a deep groove hardened part with a complex shape of an alloy structural steel having a large diameter and a deep blind hole.

[0009] To solve the above technical problems, the present invention provides a machining method for a deep groove hardened part with a complex shape of an alloy structural steel, which is characterized by including 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, and a machining allowance of 10 mm is reserved for the total length. Then perform non-destructive testing.

[0011] S2. Rough turning of the outer diameter: Clamp the blank between the chuck and the tailstock and rough turn the outer diameter. Leave a machining allowance of 3 mm - 4 mm for each outer diameter and 1 mm - 2 mm for the length of the step. Adjust the steady rest to support the workpiece and then turn the end face.

[0012] S3. Re-clamping after turning around: Re-clamp and turn the other end face, controlling the machining allowance for the total length of the workpiece to be 3 mm - 4 mm.

[0013] S4. Deep hole drilling: Use a combined drill and reamer for deep hole drilling. Leave a finishing allowance of 3 mm for the hole diameter. Replace with a flat-bottom drill to machine the bottom of the hole to be 0.5 mm smaller than the hole depth. Fix the tool with a special tool holder and adjust the tool axis to coincide with the machine spindle axis through a height gauge and a magnetic dial indicator.

[0014] S5. Quenching: Heat the workpiece to 880 °C and hold for 3 h - 3.5 h. Use a special internal spraying quenching device for oil quenching. The tempering temperature is 350 °C - 400 °C. After the hardness is detected to be qualified, enter the finishing process.

[0015] S6. Semi-finishing of the outer diameter: Clamp with a three-jaw chuck and a sector center. Leave a machining allowance of 2 mm - 3 mm for semi-finishing the outer diameter, ensuring that the circular runout ≤ 0.02 mm.

[0016] S7. Finishing the right end face and deep blind hole: Clamp with a four-jaw chuck and a steady rest. Complete the machining of the thread bottom hole, the counterbore inner hole and the thread through a multi-purpose tool with positive and negative double cutting heads. Use a special double-tipped tool to turn the inner end face of the deep hole, ensuring flatness.

[0017] S8. Finishing the left end face and the left end blind hole: Adopt the same clamping method as in S7 to turn the left end face and the inner hole.

[0018] S9. Machining the wire threading hole: Milling an equally divided platform on a machining center and drilling a φ20 wire threading hole.

[0019] S10. Wire cutting the deep groove and the outer circle arc: Clamp the workpiece with a high-precision indexing plate and a threaded positioning shaft. Machine the six equally divided deep grooves and the outer circle arc grooves through wire cutting. Fill the inner hole with cutting fluid to enhance chip evacuation.

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

[0021] Beneficial effects: The present invention optimizes the process route for alloy structural steel deep groove hardened parts with complex shapes, adopting a step-by-step machining strategy of "rough turning → deep hole pre-machining → quenching → semi-finishing → finishing → wire cutting → precision milling", reducing the influence of quenching deformation.

[0022] A variety of special tools and fixtures are used in different processes to solve the problems of high processing precision, long cycle, high cost and easy scrapping of parts caused by large-diameter deep blind hole alloy structural steel complex shape deep groove quenching hardware.

[0023] The use of integrated drilling and expansion deep hole drill, large hole deep hole flat bottom drill, deep blind hole double-blade endoscope special CNC vibration reduction tool bar, rapid indexing device, special internal cooling quenching device, enhanced rigidity, internal spray quenching furnace body and special hanger to achieve rapid and uniform cooling. The combination of high-precision vertical and horizontal conversion indexing plate and adjustable center high tailstock ensures the processing accuracy of six-equally divided deep grooves and arcs. This solves the problem of large-diameter deep hole alloy structural steel complex shape deep groove quenching hardware processing.

[0024] Tool life is increased by 30%, and machining cycle is shortened by 40%. The roundness error of deep blind holes is ≤0.02mm, and the indexing accuracy of six-divided deep grooves is ≤±5′. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the rough material

[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 deep hole drilling

[0029] Figure 5 Schematic diagram of drilling and expanding deep hole drilling tool and tool holder

[0030] Figure 6 Completed flat bottom processing diagram

[0031] Figure 7 Flat bottom tool diagram

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

[0033] Figure 9 Schematic diagram of internal spray quenching workpiece hanger

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

[0035] Figure 11 Schematic diagram of thread, stop and empty groove processing

[0036] Figure 12 Schematic diagram of tool and tool holder for thread, stop and empty groove processing

[0037] Figure 13 Schematic diagram of precision turning inner hole and flat deep hole end face

[0038] Figure 14 Schematic diagram of the tool and tool bar for precision turning the inner hole and the end face of the flat deep hole

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

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

[0041] Figure 17 Schematic diagram of the clamping for six - equal - division circular arc machining

[0042] Figure 18 Schematic diagram of the part after six - equal - division circular arc machining is completed

[0043] Figure 19 Schematic diagram of the finished part

[0044] Figure 20 Schematic diagram of the special tool holder

[0045] Figure 21 Stereogram of the internal - spray quenching furnace body Specific implementation manners

[0046] To make the objectives, contents and advantages of the present invention clearer, the following further describes in detail the specific implementation manners of the present invention.

[0047] A processing method for an alloy structural steel complex - shaped deep - groove hardened part proposed by the present invention, wherein the center of the hardened part is a deep blind hole, six deep grooves are equally distributed, and six circular arc surfaces on the circumference are connected;

[0048] Specifically, it includes the following processing steps:

[0049] S1. Blanking: Select 35CrMnSiA round steel (GB / T3077 - 2015), and perform non - destructive flaw detection on 100% of the raw materials.

[0050] Select the material with a diameter dimension 10 mm larger than the finished size of the workpiece, and leave a machining allowance of 10 mm for the full length, as Figure 1 shown. Non - destructive flaw detection: Ensure that there are no defects such as cracks and pores inside the material.

[0051] S2. Rough - turn the outer diameter and the end face: Clamp and center - support the "blank 1" that has been blanked, and rough - turn the outer diameter. Leave a machining allowance of 3 mm - 4 mm for each outer diameter, and leave a machining allowance of 1 mm - 2 mm for the length of each outer - diameter step to ensure the finishing allowance after quenching, as Figure 2 shown. Keep the workpiece stationary, place a long pad on the machine tool guide rail, place an adjustable V - block on the pad to support the workpiece and remove the center point. Install the steady rest, move the center point in to tightly hold the workpiece, and remove the long pad and the adjustable V - block. Adjust the support claws of the steady rest to support the workpiece, and turn the end face of the workpiece until it is shiny.

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

[0053] S3. Turn around and clamp: Clamp one end and support the other end. Turn around and clamp to machine the other end face, controlling the allowance for the full length of the workpiece to be 3 mm - 4 mm for finish machining after quenching.

[0054] S4. Deep hole pre-machining: Clamp one end and support the other end. Use a combined drill and reamer for deep holes to drill the deep hole, and then use a flat-bottom drill to machine the bottom plane of the deep hole;

[0055] The combined drill and reamer for deep holes includes:

[0056] The main body of the combined drill and reamer for deep holes: It includes a centering drill 4, a drain hole 5, a blade holder 6, blades 7, blade locking bolts 8, locking bolts 9, a tool body 10, a clamping groove 11, and a sealing groove 12;

[0057] The blade holder is fixed to the front part of the tool body by a locking bolt. The blade is fixed on the blade holder by a blade locking bolt. Four blades 7 are fixed on both sides of the tool body 10 at 180° by locking bolts respectively. After rotating 180° for one side of the two blades, they are staggered with respect to the two blades on the other side. This structure can ensure that the position that cannot be machined by one side of the blade can be machined by the other side of the blade when using standard CNC tool bits, thus realizing large-diameter drilling. The multi-blade design can also extend the service life of the overall tool. The design of distributing on both sides makes the cutting force more stable with respect to the tool body. The selected polygon tool has strong cutting resistance. The annular V-groove formed by cutting can ensure that the tip position is always within the annular V-groove, increasing the blade stability and having a better chip removal effect at the same time; The centering drill 4 is fixed at the center position of the front end of the tool body and is fixed to the tool body by a locking bolt. According to the machining requirements of the workpiece, 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 and machining accuracy of the tool. The centering drill is divided into two types: 120° centering drill bit and 180° centering drill bit according to the machining process, which are respectively used for front-stage centering and rear-stage flat center hole; A plurality of drain 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 machining position and the tool; The tool body 10 is designed with a chip removal groove along the spiral direction of the centering drill, which can help guide and discharge the long spiral chips generated by the centering drill; A sealing groove 12 is provided at the end of the tool body, and a sealing rubber ring is embedded in the sealing groove. Together with the clamping groove 11, it completes the sealing connection with the tool shank, increasing the stability and connection strength of the tool body;

[0058] The tool shank: It consists of a clamping block 13, a locking bolt 14, a multi-stage tool shank body 15, and a fixing groove 16. The multi-stage tool shank body increases the number of tool shank connections according to the drilling depth as required. The increased tool shanks are connected step by step by locking bolts, and a fixing groove for cooperating with the tool holder is provided at the end.

[0059] Special tool holder: made of ductile iron, with good shock absorption. The main body is cylindrical, with internal slots (adjustable slot width), with top screws (located on the slotted side of the tool holder, used to open the slot) and locking bolts (located on the closed side of the tool holder, used to fix the tool bar) on both sides.

[0060] The axes of the tool bar and the tool holder coincide with each other, and the tool holder is installed at the front end of the slide in the machine tool.

[0061] The blade 7 is a polygonal blade, preferably a WCGX06T308-Z HT0110PCS blade. The center drill is a HPD-2556C-H center drill.

[0062] The deep hole diameter leaves a finishing allowance of 3mm after quenching. The shank of the integrated deep hole drill needs to be clamped on a special tool holder, which is fixed on the slide of the machine tool with six locking bolts 83. The special tool holder is cast with ductile iron and tightly fits the tool bar of the integrated deep hole drill. It has high strength and good vibration resistance. After the tool bar is inserted into the slotted hole of the tool holder, loosen the top screw and tighten the locking bolt to clamp the tool bar.

[0063] The three special tools used in the subsequent processing are fixed by this special tool holder. The special tool holder is supported by two top screws 80 to open the slotted side of the special tool holder. The tool bar is locked on the tool holder body 82 by four locking bolts 81. Figure 20 And use the height gauge and magnetic meter to align, detect and adjust so that the axis of the integrated deep hole drill coincides with the axis of the machine tool spindle, as shown. Figure 3 shown.

[0064] Processing steps: adjust the lathe cutting parameters, the number of revolutions is 100r / min, the cutting amount is 0.2mm / revolution, and the center drill of the integrated deep hole drill is drilled to a depth of less than 1-2mm. Figure 4 , 5 Adjust the locking bolt of the drilling and expanding integrated deep hole drill and spot drill, remove the 120° spot drill bit, and replace it with a 180° spot drill bit to level the center hole.

[0065] When flattening the bottom of the hole, pay attention to timely chip removal to ensure stable cutting, carefully observe the cooling and chip removal conditions, and ensure a smooth drilling process. Flatten the bottom to less than 0.5mm of the hole depth. Figure 6 , 7 shown.

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

[0067] The first blade 18 and the second blade 19 are fixed on the tool body by blade locking bolts. On one side of the tool body 23, one first blade 18 is paired with one second blade 19, and two second blades 19 are distributed on the other side. The two sides are distributed at 180° with respect to the tool body 23. The first blade 18 is installed on the outside. After the two blades on one side rotate 180°, they are staggered with respect to the two blades on the other side. This structure can ensure that the positions that cannot be machined by the blades on one side can be machined by the blades on the other side when using standard CNC tool tips, achieving flat bottoms for large apertures. The multi-blade design can also extend the service life of the overall tool. The design of the distribution on both sides makes the cutting force more stable with respect to the tool body. After the first blade 18 is installed, there is no back angle on the arc in its circumferential direction, and it does not produce a cutting effect, only having a guiding effect. There is a back angle on the bottom edge, that is, on the flat bottom surface side. Cooperating with the other three second blades 19 can achieve the effect of flat bottoming without dead angles and without reaming; A plurality of liquid discharge holes 24 are longitudinally distributed along the chip discharge groove of the tool body to accelerate the cooling, lubrication, and flushing of the machining position and the tool; A clamping groove 25, a locking hole 26, and a sealing groove 27 are provided at the rear end of the tool body. A sealing rubber ring is embedded in the sealing groove for sealing connection with the tool shank. Since the cutting force generated during flat bottom drilling is large, adding the cooperation connection of the clamping groove 25 and the locking hole 26 with the tool shank can greatly improve the stability and connection strength of the tool body; The shock-absorbing centering guide block 21 is made of cemented carbide and is fixed on the tool body by locking bolts. Its outer diameter with respect to the axis of the tool body 23 is slightly smaller than the workpiece aperture. By cooperating with the inner hole wall of the workpiece, it can achieve the functions of shock absorption, centering, and guiding.

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

[0069] S5. Quenching treatment: Heat the workpiece to 880°C and hold for 3h to 3.5h. Use a special internal spraying quenching device for oil quenching. The tempering temperature is 350°C to 400°C. After the hardness is detected to be qualified, enter the finish machining;

[0070] Due to the large size of the workpiece, place the workpiece in a stainless steel lifting cage and use a 1200-degree high-temperature pit furnace with high furnace temperature control accuracy. Heat the temperature to 880°C and hold for 3h to 3.5h. Subsequently, use a special stainless steel lifting tool 32 together with the workpiece 34 and place them into the spraying quenching furnace body in the oil tank for quenching, as Figure 8 shown.

[0071] The special internal spraying quenching device includes a lifting tool and an internal spraying quenching furnace body. This lifting tool is convenient for loading and unloading workpieces, as Figure 9 shown. The lifting tool is composed 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 guiding clamp 42;

[0072] The hanging ring 35 is located at the top of the lifting tool and is fixedly connected to the cover plate, and is used to connect the overhead crane hook in the vertical direction.

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

[0074] The clamping plate 38 is located between the cover plate 36 and the connecting plate 39. When closed, its two sides contact the side of the step of the workpiece, playing a role in aligning the workpiece and providing a clamping force.

[0075] The alignment clamp 42 is located at the entrance end of the clamping space. The three guide plates below it match the outer contour of the workpiece step to ensure automatic alignment when the workpiece is inserted. One end of the alignment clamp 42 is hinged to the connecting plate 39 through a pin shaft 41, and the other end is fixed to the connecting plate 39 through a movable pin 40. After closing, the movable pin 40 is inserted, and the upper end face of the alignment clamp bears the gravity of the other half of the bottom step 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 into it, which plays a positioning role when welding the cover plate 36, the clamping plate 38, and the connecting plate 39.

[0077] During use, the movable pin 40 is pulled out, the alignment clamp 42 is opened, one side of the step at the bottom of the blind hole of the workpiece is inserted between the cover plate 36 and the connecting plate 39, the alignment clamp 42 is closed, the movable pin 40 is inserted, the overhead crane hook is hung into the hanging ring 35, and the overhead crane is started for lifting, realizing the lifting of two workpieces at a time.

[0078] Since the workpiece has a blind hole structure at one end, to improve the overall quenching effect, a special internal spraying quenching furnace body is placed in the oil tank, as Figure 10 shown, which is composed of a hanging ring 43, a guiding ring 44, a circulation hole 45, an oil delivery pipe 46, an oil injection nozzle 47, and a furnace body frame 48.

[0079] The guiding ring 44 is fixedly welded at the top opening of the furnace body frame 48 and cooperates with the six guide plates at the lower end of the alignment clamp 42 of the workpiece lifting tool to realize rapid furnace entry under the condition of shaking during the lifting operation, and at the same time play a role in concentric positioning between the opening side of the workpiece and the oil injection nozzle 47 to ensure the concentricity between the workpiece and the oil injection nozzle 47.

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

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

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

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

[0084] After the overhead crane lifts the workpiece with a special stainless steel sling, under the joint alignment of the alignment clamp 42 and the guiding ring 44, the workpiece is covered on the nozzle. This furnace body has good cooling performance, can ensure the hardening depth, the tempering temperature is 350°C - 400°C, the hardness is detected by a high-precision portable Rockwell hardness tester, and samples are taken from the furnace specimens for processing and testing. After the performance parameters are qualified, finish machining is carried out after quenching.

[0085] Through the precise cooperation of the guiding ring and the sling, the layout design of the nozzle and the efficient oil circuit design, this quenching furnace body significantly improves the hardening depth and cooling uniformity, and solves the problems of deformation and uneven hardness of large-sized hardened parts.

[0086] S6. Semi-finish machining the outer diameter

[0087] For the quenched workpiece, one end is supported by a three-jaw chuck for the inner hole, and the other end is supported by a sector center. The allowance for semi-finish machining the outer diameter is 2mm - 3mm. Each outer diameter dimension is completed in one clamping, and magnetic gauge detection is carried out. The circular runout of each outer diameter is within 0.02mm, ensuring the roundness and circular runout accuracy of the outer diameter reference, and ensuring the dimensional accuracy and form and position accuracy of each inner hole dimension during finish machining.

[0088] S7. Finish machining the right end face, deep blind hole screw hole, and stepped hole: Use a four-jaw chuck and a steady rest for clamping. Through a multi-purpose tool with double positive and negative cutting heads, the thread bottom hole, counterbore inner hole, and thread processing are completed. A special tool with double cutting tips and an endoscope damping tool rod are used in combination to turn the inner end face of the deep hole to ensure flatness;

[0089] Use a numerically controlled lathe with relatively high precision, and use the clamping method of one chuck and one steady rest with a four-jaw chuck. Clamp the workpiece with a four-jaw chuck and place two magnetic gauges near the chuck and the tailstock ends of the workpiece 17 to align the workpiece. When the pointer of the magnetic gauge at the two points jumps within 0.03mm, use the support claws of the steady rest to contact and support the workpiece, and the support force should be appropriate, neither too large nor too small.

[0090] Install a multi-purpose tool with double positive and negative cutting heads and complete the thread bottom hole, counterbore inner hole, and thread processing, as Figure 11 、 12 shown. Since the thread cutting tip is facing downwards with a reverse thread, without changing the rotation direction of the lathe, the tool is moved to the opposite side to cut the thread. This tool saves the time for tool conversion and clamping.

[0091] The double-sided multi-purpose knife with two cutting heads consists of an internal-thread blade 49, a precision-machined blade 50, a tool body 51, a blade locking bolt 52, a locking bolt 53, a drain hole 54, and a meshing thread 55;

[0092] The precision-machined blade 50 uses a CNMG 120408-PM 4415 blade;

[0093] The precision-machined blade 50 and the internal-thread blade 49 are locked by the blade locking bolt 52 and fixed at 180° on both sides of the tool body 51. The internal-thread blade is located on the left side at the front end of the tool body, and the precision-machined blade is located on the right side. By moving the spindle in the positive and negative directions of the X-axis through a numerical control machine tool, the precision machining of the inner end face of the deep hole and subsequent thread turning are respectively carried out. A plurality of drain holes 54 are provided along the chip discharge 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 a meshing thread 55 that cooperates with the end of the endoscope damping tool bar, and the axial and radial stable and high-strength connection with the tool bar is realized through the meshing action of the meshing threads and the locking of the locking bolt.

[0094] The endoscope damping tool bar consists of a meshing thread 55, a locking bolt 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 side of the front end of the tool bar and is fixed on the tool bar by a locking bolt. Considering that the supplementary light 58 and the wide-angle camera 59 may be easily damaged during the machining process, they are designed as a quick-insert structure and inserted into the wide-angle wired camera module 57 for use. The wired camera module 57 is the main board for power supply and signal transmission, etc.; The inside of the tool bar body is hollow and provided with a drain hole 54; A wire groove 60 is opened on the surface of the tool bar body for wiring the wide-angle wired camera module; The front end of the tool bar is provided with a meshing thread that cooperates with the meshing thread at the end of the tool body 51;

[0095] The meshing thread of the double-sided multi-purpose knife with two cutting heads is pressed into the meshing thread at the front end of the tool bar and fixed by a locking bolt; The camera module is connected to an external display or a mobile terminal through a wire groove to realize the function of real-time monitoring of the turning state.

[0096] Since the deep blind hole has a deep aperture and a tolerance requirement for the hole depth, when turning the deep blind hole, the inner bottom surface 61 needs to be machined. To increase the clamping rigidity of the tool bar, a damping tool bar and a special tool holder are required, and they are fixed on the middle tool rest of the lathe by a bolt 83. Use a setscrew 80 to expand the clamping hole of the grooved tool bar of the special tool holder. The clearance between the clamping hole of the tool bar and the tool bar is 0.02 mm to 0.04 mm. Install the endoscope damping tool bar on the clamping hole of the grooved tool bar of the special tool holder. The length of the tool bar extending out of the tool holder is 2 mm to 4 mm greater than the depth of the deep hole of the workpiece. Loosen the setscrew and lock the locking bolt.

[0097] Since the length-diameter ratio of the workpiece hole reaches 10 times the diameter, in order to increase the rigidity of the tool bar, the cross-sectional area of the tool bar should be increased as much as possible. The spatial distance between the outer diameter of the tool bar and the inner wall of the deep hole is less than the distance from the tip of the standard tool head to the center of the workpiece at the inner end face of the deep hole. The special double-tip tool for turning the deep hole and the inner end face of the deep hole is clamped on the endoscopic vibration-damping tool bar. Use the turned end face of the workpiece to align the tool, and slightly adjust the position of the tool holder so that the two tips of the special double-tip tool contact the workpiece end face at the same time. The first tip of the special double-tip tool is used to turn half of the distance from the inner hole and the inner end face at the deep hole diameter to the center of the inner end face, and the second tip is used to turn from the middle of the inner end face of the deep hole to the center of the workpiece and ensure the flatness of the turned inner end face of the deep hole.

[0098] As Figure 13 、 14 shown, the special double-tip tool consists of a blade 62, a blade locking bolt 63, a tool body 64, a locking bolt 65, a drain hole 66, and a meshing thread 67. The endoscopic vibration-damping tool bar 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 a VBMT 160408-PM 4415 blade;

[0100] There are two blades 62 in total. Their cutting edges are in the same plane and are locked and fixed on one side of the tool body 64 by the blade locking bolt 63. The double-head design can avoid the situation where part of the inner end face tool cannot be machined due to the interference between the tool bar and the tool during movement and the inner wall of the workpiece, and improve the processing efficiency; there are two drain holes 66 at the bottom of the blade to speed up the cooling, lubrication, and flushing of the processing position and the tool; the bottom of the tool body 64 is provided with a meshing thread 67 that cooperates with the end of the endoscopic vibration-damping tool bar, and realizes the axial and radial stable and high-strength connection with the tool bar through the meshing action of the meshing threads and the locking of the locking bolt.

[0101] The endoscopic vibration-damping tool bar 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; the wide-angle wired camera module is located on the front side of the tool bar and is fixed on the tool bar by a locking bolt. Considering that the supplementary light 70 and the wide-angle camera 69 may be easily damaged during the processing, it is designed as a quick-insert structure and inserted into the wide-angle wired camera module 69 for use. The wired camera module 69 is the main board for power supply and signal transmission, etc.; the inside of the tool bar body is hollow and is provided with a drain hole 66; the surface of the tool bar body is provided with a wire groove 72 for wiring the wide-angle wired camera module; the front end of the tool bar is provided with a meshing thread that cooperates with the meshing thread at the end of the tool body 64;

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

[0103] Loosen the tool holder locking bolt, adjust the length of the damping tool shank extending out of the tool holder, and turn the stepped hole and the bottom hole of the thread at the stepped part.

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

[0105] Adopt a numerically controlled lathe with higher precision, use the clamping method of one chuck and one center rest with a four-jaw chuck, clamp the workpiece with a four-jaw chuck, and place two magnetic gauges at the ends of the workpiece close to the chuck and the tailstock to align the workpiece. When the pointer of the magnetic gauge at the two points jumps within 0.03 mm, use the supporting claws of the center rest to contact and support the workpiece, and the supporting force should be appropriate, not too large or too small. Replace the special indexable tool head on the damping tool shank to turn the end face to control the overall length, inner hole and inner end face of the workpiece.

[0106] S9. Machine the wire threading hole: Mill the equally divided platform on the machining center and drill a φ20 wire threading hole;

[0107] Clamp the workpiece on the fourth-axis chuck of the machining center, and align the outer circle runout of both ends of the workpiece to be less than 0.02 mm. Mill an equally divided and evenly distributed 6-20×20 platform at the center of the workpiece length and the center of the circumferential diameter, and drill a φ20 hole that penetrates the center hole, which is used as the wire threading hole for wire cutting and the liquid drainage hole for water jet cutting, as Figure 15 shown.

[0108] S10. Wire cut the deep groove and the outer circle arc groove: Use a high-precision indexing plate and a threaded positioning shaft to clamp the workpiece, wire cut the equally divided deep groove, and then clamp the workpiece through the adjustable support fixture for the equally divided outer circle arc, and machine the equally divided outer circle arc groove;

[0109] Install the high-precision indexing plate on the wire cutting machine guide rail, connect the part support vertical plate to the wire cutting machine guide rail and the conversion indexing plate with bolts to enhance the strength and stiffness of the indexing plate when used in the horizontal state. Install the adjustable center height tailstock on the wire cutting accessory base and connect it to the machine guide rail, manufacture the threaded positioning shaft, and make the positioning shaft by mating the part thread and the stop, with the clearance between the shaft and the hole being 0.03 mm to 0.05 mm. The center hole of the threaded positioning shaft is matched with the outer diameter of the Morse No. 2 center of the adjustable center point seat, with a clearance of 0.02 mm - 0.03 mm. Adsorb the magnetic gauge on the wire cutting machine guide rail, make the contact of the measuring rod of the dial indicator vertically contact the outer circle of the conversion indexing plate chuck, rotate the high-precision vertical and horizontal conversion indexing plate, observe the swing range of the dial indicator pointer and tap to align the outer circle runout of the chuck to be less than 0.02 mm, then tighten each locking nut, and conduct multiple verifications to ensure the positioning and clamping accuracy of the workpiece.

[0110] Lift the workpiece and mount it on the chuck of the high-precision vertical and horizontal conversion indexing table. Use a magnetic dial indicator to align the two ends of the workpiece within 0.02 mm. The threaded and counterbored ends of the workpiece face the direction of the adjustable center height tailstock. Screw the threaded positioning shaft onto the workpiece and move the tip shaft of the adjustable center height tailstock into the center hole of the threaded positioning shaft. Control the clearance between the shaft and the hole within 0.02 mm to 0.03 mm and tighten the lock nut to play a positioning and supporting role. Use the magnetic dial indicator again to correct the coaxiality of the workpiece within 0.02 mm.

[0111] Adjust the high-precision vertical and horizontal conversion indexing table and the machine tool guide rail to align the center position of the φ20 wire threading hole. Complete the work of threading, tightening the wire, and wire threading, and adjust the machine tool and the program to wire cut the symmetric deep groove. Use a three-way joint at the machine tool water tank to branch out a separate water pipe and place it into the φ20 wire threading hole that forms a 60° angle with the upper wire threading hole above to enhance the chip removal after the molybdenum wire discharges. After the molybdenum wire cuts out a distance of 5 mm from the φ20 hole, the cutting pauses. Use a wooden plug or cloth plug to block the other four wire threading holes except the water injection pipe and the upper hole, so that the cutting fluid fills the inner hole of the workpiece, and the molybdenum wire is completely immersed in the cutting fluid for discharge cutting, enhancing the chip removal effect and improving the processing efficiency. Set a pause point at a distance of 3 mm to 5 mm from the completion of the deep groove processing. Use a clamp to fix both ends of the deep groove to prevent the lower key-shaped metal cut off from falling. Use a strong magnetic chuck to hold the upper key-shaped metal cut off above and prevent it from falling. Loosen the clamp and remove the lower key-shaped metal, support the upper cut-off key-shaped metal with a longer T-shaped bolt, loosen the magnetic chuck and lift up and remove the upper cut-off key-shaped metal. Loosen the molybdenum wire on the wire spool and remove it from the guide wheel. Rotate the high-precision vertical and horizontal conversion indexing table by 60°, thread the wire through the φ20 process hole of the workpiece and complete the work of threading and tightening the wire. Adjust the machine tool and the program to wire cut the symmetric deep groove. After the molybdenum wire cuts out a distance of 5 mm from the φ20 hole, the cutting pauses. Use a key-shaped wooden plug or cloth plug to block the remaining process wire threading holes and the cut key-shaped deep groove except the water injection pipe and the upper hole, so that the cutting fluid fills the inner hole of the workpiece, and the molybdenum wire is completely immersed in the cutting fluid for discharge cutting, enhancing the chip removal effect after the molybdenum wire discharges and improving the processing efficiency. Repeat the above actions to complete the wire cutting work of the equally distributed deep grooves in six equal parts and unload the workpiece 73, as Figure 16 shown.

[0112] Mount the outer circle six-equal-part circular arc adjustable support fixture on the wire cutting machine tool guide rail. This fixture consists of a base plate 74, a positioning key locking bolt 75, a positioning key 76, a fixture body 77, a positioning plug 78, and a face bearing 79, as Figure 17 shown.

[0113] The adjustable support fixture for the six-equal-part arc of the outer circle is symmetrically distributed left and right. Its mounting plate 74 and fixture body 77 are integrally machined by a machining center to ensure the accuracy of each hole position and the parallelism of the upper and lower planes. Fix the fixture body on the guide rail of the wire-cutting machine tool. Install the positioning key 76 at the corresponding hole position of the fixture body 77. The lower end face of the end face 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, insert one side of the deep blind hole of the workpiece into the top of the positioning plug 78 and rotate it appropriately for alignment. After alignment, push the positioning key into the diagonal deep groove of the workpiece 16 and lock the locking bolt to complete the work of threading, tightening the wire, and threading the wire. The program controls to complete the cutting of a single arc groove of the six-equal-part arc groove. The allowance on one side of the arc groove is 0.4 mm. Repeat the above actions to complete the cutting of the six-equal-part arc groove in sequence, as Figure 18 shown.

[0114] S11. Precision milling of the arc groove and hole groove: Precision mill the six-equal-part arc groove on a vertical machining center to complete the final machining of each hole and groove;

[0115] Clamp the workpiece after wire cutting on the fourth-axis turntable of the vertical machining center. First, align the coaxiality of the two ends of the outer circle of the workpiece, and finely adjust the rotation of the fourth axis with a hand-held pulse generator. Use a lever dial indicator to align the parallelism between the plane of the deep groove and the spindle of the machine tool. After alignment, take the deep groove as the reference, use an optical edge finder or a centering bar to establish the workpiece coordinate system. Manually input 60°, 120°, 180°, and 240° respectively, and use a lever dial indicator to detect the indexing accuracy of the six-equal-part deep groove surface and its parallelism with the spindle. After passing the inspection, call the tool to perform tool setting in sequence. Call the tool to perform tool setting in sequence. Call the program to complete the precision milling of the six-equal-part arc groove and the machining of each hole and groove. The finished part after machining is as Figure 19 shown.

[0116] In different processes of the present invention, a variety of special tools and fixtures are used to solve the problems of high machining accuracy, long cycle, high cost, and easy part scrapping caused by the complex-shaped deep grooves of alloy structural steel with large-diameter deep blind holes. Use a drill and reamer integrated deep hole drill, a large-hole and deep-hole flat-bottom drill, a special CNC vibration-damping tool bar for deep blind holes with double cutter heads, a quick indexing device, and a special internal cooling quenching device to solve the machining problems of alloy structural steel with large-diameter deep holes and complex-shaped deep grooves.

[0117] After machining, the roundness of the deep hole of the workpiece is ≤0.015 mm, and the symmetry of the six-equal-part groove is ≤0.03 mm, fully meeting the technical requirements of high-precision complex parts.

[0118] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can still be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A method for processing large-diameter deep blind hole alloy structural steel complex shape deep groove quenching hardware, characterized in that: The following steps are involved: S1, cutting; S2, Rough turning outer diameter: outer diameter allowance 3mm~4mm, outer diameter step length allowance 1mm~2mm; S3, turn around and clamp to turn the other end face, and control the total length of the workpiece to be 3mm to 4mm; S4, drilling deep holes, leaving a margin for the hole diameter, and processing the bottom surface of the hole to be less than 0.5mm of the hole depth; S5, quenching treatment: heat the workpiece and keep it warm, use internal spray quenching device for oil cooling quenching, the tempering temperature is 350℃~400℃, and after the hardness is tested and qualified, it will enter the finishing process; S6, semi-finishing outer diameter: use three-jaw chuck to support the inner hole and fan-shaped top support, semi-finishing outer diameter allowance 2mm~3mm, control outer diameter circle runout ≤0.02mm; S7, finishing the left and right end faces and deep blind holes: after clamping, the thread bottom hole, stop inner hole and thread processing are completed by using a multi-purpose tool with positive and negative double-tip cutters, and a double-tip special tool is used to turn the inner end face of the deep hole to ensure flatness; S8. Processing threading holes: Mill equally divided platforms at the center of the workpiece and the center of the circumferential diameter and drill threading holes; threading holes are used for wire cutting chip removal and cutting fluid injection. During the cutting process, unused threading holes are closed with wooden plugs or cloth plugs to improve chip removal efficiency; S9, wire cutting processing of six-divided deep grooves and outer circular arc grooves; S10, precision milling of arc grooves and hole grooves: On the vertical machining center, a coordinate system is established based on the deep groove, and the arc grooves are precision milled in six equal parts and the processing of each hole and groove is completed.

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

3. The processing method according to claim 1, characterized in that: In step S5, the workpiece is heated to 880°C and kept at this temperature for 3h to 3.5h.

4. The processing method according to claim 1, characterized in that: In step S4, a deep hole is drilled using a drilling and expanding deep hole drill, the drilling and expanding deep hole drill is fixed on the slide of the machine tool through a special tool holder, and the drill axis is adjusted to coincide with the machine tool spindle axis through a height gauge and a magnetometer.

5. The processing method according to claim 4, characterized in that: The drilling and expanding integrated deep hole drill comprises a drilling and expanding integrated deep hole drill body and a cutter bar; the drilling and expanding integrated deep hole drill body comprises a center drill 4, a blade holder 6, a blade 7, and a cutter body 10; the blade holder is fixed to the front of the cutter body, the blade is fixed on the blade holder, and the center drill is fixed to the center of the front end of the cutter body; four blades 7 are fixed at 180° on both sides of the cutter body 10 by locking bolts, and the two blades on one side are rotated 180° and staggered relative to the two blades on the other side; the rear end of the cutter body is connected to the cutter bar.

6. The processing method according to claim 5, characterized in that: The tool bar includes a multi-stage tool bar body 15 and a fixing groove 16; the multi-stage tool bar body increases the number of tool bar connections according to the drilling depth, and the added tool bars are connected step by step through locking bolts. A fixing groove is provided at the end of the multi-stage tool bar body.

7. The processing method according to claim 1, characterized in that: The processing steps of step S4 are: adjust the lathe cutting parameters, the number of revolutions is 100r / min, the feed amount is 0.2mm / revolution, the center drill of the integrated deep hole drill is drilled to a depth of less than 1-2mm, the 120° center drill is removed, and a 180° flat bottom drill is replaced to flatten the bottom of the hole to a depth of less than 0.5mm.

8. The processing method according to claim 1, characterized in that: In step S5, the internal spray quenching device includes a hanger and an internal spray quenching furnace body, the hanger includes a cover plate 36, a clamping plate 38, a connecting plate 39 and a guiding clamp 42; the cover plate 36 and the connecting plate 39 are arranged in parallel, and a horizontal clamping space is formed between the two to accommodate the bottom step of the blind hole of the workpiece; the clamping plate 38 is located between the cover plate 36 and the connecting plate 39, and when closed, its two sides are in contact with the side of the step of the workpiece to provide a clamping force; one end of the guiding clamp 42 is hinged to the connecting plate 39 through a pin 41, and the other end is fixed to the connecting plate 39 through a movable pin 40; the internal spray quenching furnace body includes a guide ring 44, an oil nozzle 47, and a furnace frame 48; the oil nozzle 47 is installed in the furnace frame 48, and the guide ring 44 is fixed at the top opening of the furnace frame 48, and cooperates with the guiding clamp 42 of the workpiece hanger to position the workpiece concentrically with the oil nozzle 47.

9. The processing method according to claim 1, characterized in that: In step S7, the first tool tip of the double-tip special tool is used to turn the inner hole and the 1 / 2 of the distance from the inner end face to the center of the inner end face at the diameter of the deep hole, and the second tool tip is used to turn the 1 / 2 of the inner end face of the deep hole to the center of the workpiece and ensure the flatness of the turned inner end face of the deep hole.

10. The processing method according to claim 1, characterized in that: In step S9, a high-precision vertical-horizontal conversion dividing plate is used for positioning, and molybdenum wire discharge cutting is used to cut six equally divided deep grooves and six equally divided arc grooves on the outer circle, with a single-side allowance of 0.4mm; the six equally divided arc grooves on the outer circle are processed using an adjustable support fixture, and the precise positioning of the workpiece is achieved by the matching clearance of the positioning key and the deep groove of 0.03mm to 0.05mm.

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