In the past, old-fashioned, low-speed C620 lathe spindles were installed with sliding bearings. Although sliding bearings have the advantages of simple structure, easy manufacturing, low cost, smooth operation, and insensitivity to shock and vibration, they are far from modern cutting tools. High-speed, high-precision, high-efficiency requirements, and it is difficult to repair after wear, the surface roughness and accuracy of the machined parts is poor, and the productivity is also low. To this end, the C620 lathe spindle bearing was reconstructed. The specific steps are as follows (see the attached drawing): Modification of the front bearing hole of the headstock 1 The front bearing bore of the headstock 1 is machined to Ø150K6. In order to facilitate the loading and unloading of the bearing, a hole of Ø151 mm and a length of 55 mm is machined at the left end of the bearing hole. In addition, drilling Ø16mm hole, easy to operate the fastening screw 5.
1. Headstock 2. Adjusting nut 3. Spindle 4. Nut stop pad 5. Fastening screw 6.3182120 bearing 7. bearing cap pressure ring 8. bearing cap improved C620 lathe spindle bearing
Modification of the spindle 3 A thread of M100×1.5 mm is machined on the spindle 3 in the size and position shown in the figure, and the adjustment nut 2, the nut stopper 4 and the fastening screw 5 are arranged. 2 The taper of 1:12 is machined on the spindle 3 according to the position and size shown in the figure and the inner taper hole of the bearing 6 is matched. The bearing cover 8 and the bearing cover press ring 7 are machined and the original sliding bearing adjustment nut is threaded to be machined to the dimensions of the bearing cover 8 as shown in the figure (unlabeled dimensions are already existing for the original part). 2 The original bearing cover press ring is machined into the size of the bearing cover press ring 7 as shown in the figure. Spindle 3 Axial Fluctuation and Radial Clearance Adjustment 1 The amount of spindle axial misalignment is adjusted with the adjustment nut at the rear end of the spindle. The measured amount of misalignment of the spindle shoulder support surface should be 0.015 mm. 2 The radial runout of the centering journal of the spindle is adjusted by the adjustment nut 2, so that the bearing 6 obtains a slight radial clearance, and the radial runout of the spindle centering shaft head should be 0.02 mm. The accuracy of the machine tool after modification is measured as follows: The radial runout of the spindle centering shaft head is 0.01 to 0.03 mm: The axial shaft motion amount is 0.015 mm: The parallelism of the spindle axis and the slider movement is 0.02 mm in the length of 300 mm (in the vertical In the horizontal plane): The verticality of the transverse tool holder's lateral movement to the spindle axis is 0.02mm (concave) at 3000mm: The height deviation of the top tips of the headboard and the tailstock is 0.03mm: The finishing vehicle is on a 300mm long shaft. The outer circle measured: roundness of 0.02mm and cylindricity of 0.03mm: the flatness of the end face of the finishing carriage on the 300mm diameter was 0.02mm (concave): The roughness of the machined surface was Ra6.3 to 3.2mm. The above data conforms to JB2670-82 "General Rules for Inspection of Metal Cutting Machine Accuracy". The quality of the product has been significantly improved compared to machines that have not modified the spindle bearings.
