Process analysis The workpiece was originally machined on a CNC lathe. During the finishing process, the inner hole and the inner spherical surface were required to be turned once, and the tool change was not allowed during the machining process. According to the processing characteristics of CNC machine tools, the diameter of the tool bar can only be f60mm. Due to the slenderness of the arbor, the rigidity is insufficient, the strength is low, the vibration of the arbor is large during processing, the knife phenomenon is generated, and the roughness value of the hole wall is increased, which not only has low production efficiency, but also is difficult to ensure the processing quality. If the diameter of the arbor is increased, the gap between the arbor and the hole wall is too small when the inner hole is machined, which causes the chip removal to be unsmooth, causing clogging, difficulty in cooling the lubricating fluid, and intensive tool wear, thereby affecting the machining accuracy. In order to meet the needs of production, to stabilize the processing quality of the workpiece, improve the production efficiency, and solve the shortage of deep hole in CNC lathe machining, a special tool for turning the spherical surface in the deep hole is designed, which can be used to perform the spherical surface of the deep hole in the ordinary lathe. machining. Tool design Design special tools should maximize the strength and rigidity of the tool bar under the premise of smooth discharge of the chips, avoid the vibration of the tool bar during the machining process, ensure the machining accuracy, and realize the rotation of the tool to achieve the function of turning the inner spherical surface. According to the depth of the workpiece and the diameter of the inner hole, according to the principle of the crank-link mechanism, the special tool for turning the spherical hole in the deep hole is shown in Fig. 2. The cutter bar has a diameter of 110 mm and a length of about 2000 mm. The special tool for turning the spherical surface in the deep hole is mainly composed of a cutter bar, a knife seat, a sealing plate, a drawbar shaft, a connecting rod, a rotating body and the like. The cutter bar, the knife seat and the sealing plate are welded into a rigid body, and the pull rod shaft can slide freely in the inner hole of the seat and the sealing plate. The rod shaft and the connecting rod, the connecting rod and the rotating body are connected by a pin shaft, and the rotating body and the tool holder are connected by a positioning shaft and a sleeve. A sliding fit is used between the connectors. processing methods After the workpiece is welded, the internal stress treatment is eliminated. After the inner hole and the outer circle of the rough car, the alignment reference is established on the flanges at both ends of the workpiece. In order to solve the problem of poor rigidity of the workpiece, the deformation of the clamping is avoided, and the workpiece is fixed by the positioning tool and the center frame. The positioning tool is clamped by the chuck, and after the positioning flange of the outer circumference of the workpiece flange is positioned, the workpiece is bolted in the positioning tool by the positioning of the mouth, and the workpiece is supported by the two center frames. The special tool is mounted in the holder mount, and the special tool is fixed by the open groove of the holder mount. Secure the shank mount to the tool holder of the lathe. The connecting seat is fixed on the end surface of the tailstock shaft, and the pull rod shaft is hinged to the connecting seat through the positioning pin. When turning the inner spherical surface, the operating handle of the lathe tailstock is rotated, and the axial movement of the tailstock sleeve is used to move the pull rod shaft in the axial direction through the connecting seat fixed on the tailstock sleeve, and the pull rod shaft pushes the connecting rod and the connecting rod The turning tool on the rotating body is rotated around the positioning axis to complete the turning of the spherical surface in the deep hole. The processing is shown in Figure 3. When turning, the tool is punched at the workpiece hole to control the size of the inner hole and the inner spherical surface. The depth dimension is controlled by measuring the inner depth and using the scale value of the large pallet of the lathe. The cooling lubricant uses a vulcanized cutting fluid. The coolant delivery pipe is fixed to the tool holder by the cutter bar, so that the cooling lubricant is directly sprayed from the tool holder to the turning tool, and the chips are punched out from the inner hole of the workpiece. In order to prevent the chips from being wound around the turning tool, the wall of the hole is pulled, and the appropriate chip breaking groove is ground on the turning tool according to the cutting amount during the finishing of the car to control the chip breaking effect. When finishing the car, the blade material is YW1, the spindle speed is 20r/min, the feed rate is 0.15mm/r, and the depth of the knife is 0.25mm. To maintain the sharpness of the turning tool, enhance the strength of the cutting head, improve the heat dissipation conditions, reduce the friction and the resulting work hardening tendency, the turning tool should also have a reasonable cutting angle. Observe the shape and color of the chip at any time during processing, pay attention to the condition of chip removal, and the sound of the tool in the deep hole during machining, and touch the knife bar to observe the vibration. In the event of an abnormality, it should be checked immediately and measures taken to resolve it. in conclusion The turning of the spherical surface in the deep hole is realized by a special tool on a common lathe. Not only is production efficiency high, processing costs are reduced, but processing quality can be guaranteed. The special tool for processing the spherical surface in the deep hole is simple in structure, convenient to use, and the processing size can be adjusted, and the applicable range is large. It can provide a reference for solving similar problems.
Application
· Mesh weaving.
· Tying wire in architectural site.
· Making handicrafts.
· Material of mesh and fence.
· Packing life products.
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Figure 1 workpiece 
1. Turning tool 2. Rotating body 3. Connecting rod 4. Tool holder 5. Tool holder 6. Pull rod shaft
7. Sealing plate 8. Positioning shaft, bushing, nut, washer 9. Pin shaft Figure 2
In order to avoid the dead point of the link mechanism during the turning of the spherical surface, the rotating body should be deflected forward by an angle when assembling the special tool. 
1. Machine headstock 2. Three-jaw chuck 3. Positioning tool 4. Fixing bolt 5. Workpiece 6. Special tool
7. Center frame 8. Tool holder mounting 9. Machine tool holder 10. Linking seat 11. Tailstock sleeve 12. Machine tailstock Figure 3
Spherical turning in deep holes (figure)
The workpiece is shown in Figure 1. The material is 1Cr18Ni9Ti, welded structural parts. Although the material strength of the workpiece is not high, the plasticity and toughness are large, the machinability is poor, the work hardening tendency is strong, the cutting load is large, the thermal conductivity is poor, and heat is easily concentrated on the cutting edge during processing, resulting in built-up edge and increased tool wear. The main difficulty in processing is the high precision of the workpiece, thin wall, poor rigidity, and easy to cause deformation of the clamping. The hole of the workpiece is deep and blind, the bottom of the hole is spherical, the shank is slender, and vibration is easy to occur when turning. Processing quality is not easy to guarantee.