The graphite electrode is one of the important consumables in the electric furnace steelmaking process, and it occupies a large proportion in the production cost. In the production, several graphite electrodes are connected together with taper threads. After the previous section is consumed, the rear end is reconnected and used continuously. Graphite electrode is also a fragile product. It will inevitably cause damage, tripping, and breaking during transportation, lifting, and use, resulting in an electrode that cannot be used. The electrode is expensive, and it is of great significance to process and reuse the damaged electrode. Important in the electrode processing is the taper internal thread processing.
Figure 1 Graphite electrode taper thread
1 graphite electrode processing problems graphite electrode taper threaded graphite electrode taper thread shown in Figure 1, 301 electric furnace graphite electrode diameter D has Ø450mm and Ø350m two, taper K are 1:3 two diameters of the electrode have Two kinds of pitch, taper hole diameter and depth have changed. Problems with machining on ordinary lathes Conventional lathes do not have the function of machining taper threads. The workpiece diameter is too large and the length is up to 1800mm. It is inconvenient to install it in the conventional way. The end surface of the broken electrode is uneven and the chuck claw is too short to clamp the workpiece. The size of the inner frame hole diameter, the friction between the center frame supporting claw and the outer circle of the workpiece, and the too soft electrode material solve the problems. There is a high demand for lathe gyration radius and bed length. The screw hole diameter is larger and there is no suitable twist drill. Remedy Design A set of special mechanisms that can move axially alone and move axially along with the large pallets at the same time to produce radial movements, solve the taper processing, and use the original turning tool and machining thread function of the lathe. Using the method of fixing the workpiece (not rotating or moving in the axial direction), it solves the difficulties of workpiece clamping and center frame hole too small and supporting claw friction; if the length of the bed is not enough, a bracket is added in the direction of the tail of the bed to use Fix the workpiece. Design special tools and drills. 2 Dedicated mechanism design The special mechanism for machining the internal thread of the graphite electrode taper on an ordinary lathe is shown in Fig. 2. The spindle 3 has a chute corresponding to the inclination of the workpiece and a sliding keyway for transmitting rotary power. Drives the spindle to rotate and slides in the spindle hole. The main shaft 7 drives the three carriages and the extension cylinder 12 and the clamp block 13 to rotate together. When the current locking screw 2 locks the spindle 3, the spindle 3 only rotates without axial movement, and the spindle 7 rotates one side and one side follows. The large lathe of the lathe moves toward the end of the bed, and the spindle 3 slides in the spindle hole. The sliding chute on the spindle 3 forces the two-way carriage 9 to move in a radial direction. The two-way carriage 9 drives the fine-adjusting carriage 11. The extension barrel 12, the clamping block 13 and the tool are moved synchronously to achieve taper threading. When the locking screw 2 is loosened and the rear locking screw 4 is locked, the spindle 3 transmits the rotational power and moves axially synchronously with the spindle 7, so that the machining of the end face and the cylindrical hole can be performed. The trimmer carriage 11 is used to adjust the amount of radial feed control.
1. Headstock 2. Front locking screw 3. Spindle 4 Rear locking screw 5. Sliding key 6 Headstock 7. Spindle 8. Fixed carriage 9. Two-way carriage 10. Chute slide pin 11. Trimming Plate 12. Extension tube 13 Clamping block 14. Electrical plate 15. Retention frame 16. Slant slot 17. Lathe carriage Fig. 2 Schematic drawing of dedicated mechanism
3 Mechanism installation and operation essentials Remove the feed block screw nut, small carriage, knife holder and tailstock in the lathe, and install the spindle box on the middle drag plate. The axis of rotation of the calibration mechanism and the axis of rotation of the lathe spindle are coincident and fixed. The middle position is dragged so that the middle carriage does not move due to cutting force, vibration, etc., and the rotation axis does not overlap. The front face and the cylindrical hole must be loosened before the locking screws are tightened. After the locking screws are tightened, the processing cone holes and threads are reversed—before tightening and loosening. The lathe is to be opened by a lathe, the knife is turned toward the end of the bed, the tool is reversed, the Ø450mm face is machined first, and after drilling to the required depth, the inner face of the hole is machined with a 200-mm-long tool, and the taper hole is processed to the required size with a common reverse-spindle. , and finally thread processing. 4 Electrode Processing Conditions and Problems Electrode Processing Conditions Using an old C620×1000mm lathe with a relatively low accuracy, a special mechanism was installed on the large carriage of a lathe and processed in the manner described above. During processing, all parts of the special mechanism are accurate, reliable and easy to operate. Since November 1998, graphite electrodes have been batch processed. After the product is inspected, the geometric dimensions meet the requirements of the drawings. After trial and trial in electric furnace smelting, no tripping phenomenon was found and the connection was firm enough to meet the production requirements. The dedicated agencies are still improving the local two-way carriages and fine-adjusting carriages to increase the size scale, which can control the feed rate more conveniently and intuitively than the fine-adjustment of the screw scale. Two-way dragging dovetail increases lube grooves. Fine-tuning of the screw and handwheel is further improved and the existing one is not very flexible.
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