1. The purchase of second-hand lathes depends on whether there is serious wear inside

After reading the whole, look inside to see whether the navigation is seriously worn, whether the gears of the gearbox are seriously worn, and whether the vicinity is complete. There will be traces of use after the lathe is used, but the polished guide rail is quite bright. Careless polishing is easy to cause small traces on the guide rail, which indicates that the guide rail has been processed.   

2. Test whether the second-hand lathe is easy to use. The test lathe is the most useful

During the test, pay attention to:   

• Generally, the accuracy and stability of the processing parts of this second-hand machine tool are judged by running the equipment continuously for 12 hours, so as to determine the processing accuracy of this machine tool.  

• When testing the machine tool, you should pay attention to the sound to see whether the machine tool makes abnormal noise or has a large noise. If there is abnormal sound, observe the key parts of the abnormal sound. If the flywheel rotates with a sound, it means that there is not enough oil in use, and the flywheel bearing bush is seriously worn. If the sliding block vibrates loudly every stroke of stamping, it means that the crankshaft clearance is large, the wear is serious, and the vertical accuracy is not high; When there is noise, pay special attention to the spindle, and whether there is a fan like sound at high speed. If so, there is a problem with the spindle bearing.

• Whether the movement of the workbench is flexible, whether the tool is moving smoothly, and whether the processed workpiece can meet the process requirements. When hanging the knife, try not to drop the knife when you can bear it. If it is fast, try again fast to see whether it is normal or not. It would be better if we could test the parts and see if there are other invisible faults.   

• Pay attention to the parallelism of the machine tool and the parallelism of the table top and the sliding block ground. You can use a dial indicator to slide on the table top and measure the top of your head against the sliding block ground. Slide back and forth to see if the parallelism is good enough. The national standard punch above 60t is 0.1mm per 10cm. Exceeding this value means that the parallelism of the machine tool is not good. It needs to be adjusted.   

• The closure of the movable structure of the punch, (during production, if the gap is too large, it will not be found, and the die is easy to be damaged)