(2) Auxiliary center frame: The auxiliary center frame is used in conjunction with the transition sleeve to support the part of the workpiece beyond the length of the front and rear of the lathe. Install the free center frame on the movable base. There are four adjustable screws under the base with T-shaped grooves for adjusting and fastening the center frame. Four adjustment screws adjust the height of the center frame. For more articles, please refer to "Mechanical Workers" Cold Processing 2007 No. 1 Previous page The COVID-1 box of 9 common methods and rapid runny nose detection reagents are used for detection, the purpose is to determine the symptoms of SARS-CoV-2 infection simply and quickly, and it can sensitively determine the detection method of early infected people, which can be used for detection.
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2. Lathe adjustment
First, use the level to align and adjust the rail level. Then, a test stick is placed on the three-jaw self-centering chuck. The test stick extends 300 mm from the chuck, and the table is found to be within the upper busbar and the side busbar within 0.01 mm, and then the head is moved to the back. At the highest point of the bar at the chuck, the lathe is vacant, loosen the three fastening screws on the chuck and turn the chuck by hand. When the hands are at the highest point, tap gently with a copper rod until they are aligned. Within 0.02mm, lock the three fastening screws on the chuck clamp and turn the chuck for one week to check if there is any error and no error. For the same reason, the workpiece is used to adjust the parallel of the guide rail to the axis of the spindle. The adjustment method is as follows: First, the end surface of the workpiece is drilled, and the center hole is drilled. Then, one end of the workpiece is clamped and tightened. The 45° partial knives are used to drive the outer circumference of the workpiece at the tip end (on the vehicle), the length is 30 mm. And record the engraved value on the middle slide, then move the saddle to 100 mm from the chuck, and use the engraved value on the upper slide to make the outer circle (the car is ready), the length is 30 mm, and 50 ～75 micrometers measure the error of the outer circle at both ends. After measuring the error value, adjust the tailstock accordingly until the error value at both ends is within 0.01mm.
3. Cutting process
(1) Under normal circumstances, the elongated workpiece is easily bent under pressure and is not easily bent under tension. Therefore, the workpiece is subjected to reverse feed cutting, the axial force is directed to the tailstock direction, and the workpiece is in a tensioned state, which is not easily bent.
(2) Due to the large aspect ratio of the screw, it is not easy to adjust the cutting of the head. In order to prevent the bending deformation of the workpiece and offset the radial force during cutting, to ensure the shape accuracy and reduce the surface roughness value, Samsung and the tool holder are selected. The turret support star is made of ductile iron, and R is 1.2 times the radius of the workpiece when machining the outer circle. When turning, the supporting claw surface of the three-jaw of the tool holder should be in good contact with the surface of the workpiece, and the contact pressure should not be too large.
(3) A large amount of cutting heat will be generated during the machining process, and the cutting fluid should be added at any time. To prevent the workpiece from bending due to thermal deformation elongation, an elastic movable tip should be used. Pay attention to the wear of the support star during the cutting process and adjust it immediately.
(4) To reduce the heat of cutting, the tool should be kept sharp. In order to reduce the friction heat between the turning tool and the workpiece, the main declination is 75°, the rake angle is 20°, the back angle is 4°, and the rake angle is 5°. Grinding 3~4mm flutes can be smooth. Chip removal. It can also reduce the friction between the chip and the workpiece, and reduce the surface roughness value; grinding the chamfer of 0.15~0.20mm, -3°, can reduce the cutting force and improve the strength of the cutting edge. The blade material is YT15. When finishing the car, the 93° main angle turning tool is used, the front angle is 20°, the back angle is 6°, the polishing wiper is 0.30mm, and the rear edge of the wiper is ground to -0.5°~0.1° to make the cutting smooth. It is not easy to generate vibration; the blade material is W18Cr4V. When finishing the car, the tool tip should be slightly higher than the center of the workpiece by 0.20 to 0.30 mm.
(5) In order to prevent the influence of the cutting force on the precision of the workpiece, the roughing is performed with low rotation speed (80r/min), small back feed (3mm) and large feed (0.80mm/r). Turning. The vehicle is driven by low speed (80r/min), small back feed (3 mm) and small feed (0.40mm/r) for multi-tool feed.
(6) The key processes before turning T-threads are as follows:
Step 1: Drill the center hole with the B4/8 center end face of the left end of the car. During cutting, since the workpiece extends out of the spindle hole, the workpiece is supported by two auxiliary center frames at one end of the spindle box and the locking sleeve is locked to ensure that the workpiece coincides with the center of rotation of the spindle to prevent deformation of the workpiece due to its own weight. .
Step 2: Turn the head, the right end of the car to the total length and drill the center hole with the B4/8 center. The positioning method is the same as above. Step 3: One end of the clip (inserting the wire between the three-claw automatic centering chuck and the workpiece to function as a universal joint, and also reducing the contact surface between the three claws and the workpiece.) Tightening, the upper Samsung knife Rack, find the right, rough car outer circle to 63 mm × 3000mm. Then, move the center frame to 600 mm from the chuck, the upper transition sleeve, and adjust the table. After adjustment, tighten the front and rear adjustment screws on the transition sleeve so that the rotation center of the workpiece and the transition sleeve coincides with the rotation center of the spindle. The jitter of the watch is within 0.01mm. Loosen the chuck, remove the tailstock, move the center frame and transition sleeve together with the workpiece to the tailstock and lock. The tool nose should be 1mm higher than the center of the workpiece.
Step 4: Then proceed to the outer circle of the car. The portion of the workpiece that extends out of the tail of the lathe is supported by the auxiliary center frame in the same manner as the adjustment center frame.
Step 5: The left end of the clip is clamped tightly, and the outer circumference of each step of the rough car is left (the outer circle is left with a margin of 3 mm). The auxiliary positioning method is the same as the first step.
Step 6: Turn the head, clip the right end, top tight, the outer circumference of each step of the rough car (the outer circle is left with a margin of 3mm) and the car is 45mm × 12 mm groove to the size. The auxiliary positioning method is the same as the first step.
Step 7: Clip 30mm outer circle, upper Samsung and knife holder, find the right, fine teeth outer circle, the main declination is 93°, the material is W18Cr4V turning tool for reverse cutting. The tool nose is 0.20 to 0.30 mm higher than the center of the workpiece. Like the roughing, the positioning method is the same as that of the roughing. It should be noted that the diameter error of the outer circle at the pick-up should be within ±0.005 mm to ensure the accuracy of the T-thread of the lower car.
4. Thread cutting
The clamping, positioning and alignment methods of the T-shaped thread of the vehicle are the same as when machining the outer circle. The difference is: since the pitch of the screw is 10 mm and the direction of rotation is right-handed, the diameter of the star on Samsung and the tool holder should be increased by 25 to 30 mm, and the R value of the star is equal to the radius of the screw. Better contact with the surface of the workpiece to prevent bouncing when the T-thread is used. When the T-shaped thread is rough, the turning edge of the turning tool is 3°, the front cutting edge grinds the R2mm chip flute, the radial rake face is R65 mm, and the tooth surface roughness Ra reaches 3.2μm. Since the relief angle is affected by the helix angle, the relief angle of the left cutting edge is 5° plus the helix angle; the relief angle of the right cutting edge is 5° minus the helix angle. The radial back angle of 5° is not easy to tie the knife. The spindle speed is 80r/min, and the back-feeding knife is 0.50~0.80 mm. It is cut by straight-through method, and the width of the tool tip is equal to the width of the bottom of the groove. Pick-up thread method: 10 threads are reserved at the right end of the lathe for the tool setting. After the right, the thread can be picked up. Turn the head and leave 10 threads at the appropriate position for the tool. After the right, you can drive the rest of the thread. The precision thread cutter grinds out the V-shaped flutes. The 20° back angle of the rake angle is also affected by the helix angle. Therefore, the back angle of the left cutting edge is 5° plus the helix angle; the back angle of the right cutting edge is 5° minus the helix angle, after the radial direction. The angle is 5°, the roughness value of each angle is Ra=0.4μm, and the pick-up method is the same as the rough thread. Pay attention to the error at the joint when finishing the car, and use a small skateboard to eliminate it. The method is: after hitting the table, after measuring the upper and lower error values ​​of the joint, the number of small skateboards is moved accordingly. The method of eliminating the error on the left and right sides is the same.
In order to ensure the 30mm and 45mm outer circle coaxiality error of 0.03mm at both ends, the clamp end, the upper center frame and the transition sleeve, the table is aligned, the center hole is corrected, the top is tight, the outer end of the finishing car is rounded, chamfered, and the car Retract the slot and drive the M27 x 1.5 thread to the size. The outer circle of the right end of the head car. The method is the same as above.
Conclusion: Using the special center frame and transition sleeve, the screw rods that are driven out on the CW6280×3000 lathe according to the above steps fully meet the design specifications and meet the requirements of customers. Moreover, the tooling can also turn other similar elongated shafts and filament rods, which expands the processing capacity of the equipment and improves the utilization of the equipment.
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