1. Turning process of bearing outer ring:
Ⅰ (process) outside diameter, a face - > Ⅱ (process) car outside diameter, and the other end (process Ⅲ) car two end face and internal and external chamfering Ⅳ (process) outside ditch.
2. Turning process of bearing inner ring:
car inner diameter Ⅰ (process), a face - > Ⅱ (process) inside diameter, and the other end (process Ⅲ) car two end chamfering - Ⅳ (process) inside and outside the car ditch.
3. Analysis of quality problems in turning of bearing rings and their causes
In the turning process, due to the influence of various factors and the processing of the workpiece can not meet the technical requirements of the process, often resulting in defective products and waste products.The main types and causes are analyzed as follows.
3.1 Out of tolerance of dimension
Diameter of inner hole, diameter and width of outer circle, depth and width of channel of bearing ring are unqualified.
① The lathe is not adjusted properly.Such as: positioning datalevel is not in place or loose plug iron, drag plate is not fixed tight or knife errors.
② The measurement is not accurate.The measuring instrument is not adjusted, the standard parts are used wrong or expired wear, the table is not allowed and because the needle is wrong and "stopwatch".
(3) the tool, tool holder is not good or loose.In the process of turning tool is not in place, the size of the ring after turning changes and makes the size is not accurate.
④ The machining allowance of forging blank is large.The size difference is large, and the allowance for car processing is uneven.The material hardness is not uniform, but also make the size of the ring after turning is not uniform.Forgings to the car processing allowance is too large, so that the car processing is difficult, tool damage is serious, processing allowance is too small, so that the car after processing surface black skin, resulting in waste.
3.2 Out of tolerance of shape and position
3.2.1 Inner (outer) diameter variation, average inner (outer) diameter variation and circular deviation out of tolerance in a single radial plane
① These factors of the forging blank not only directly affect the dimensional accuracy, but also directly affect the shape and position accuracy of the turning workpiece.
(2) improper installation or calibration fixture is also easy to produce shape and position out of tolerance or deformation.Such as: fixture installation is loose or the car outside the circle clamping air clamp positioning is not correct, there is no timely correction or the spring chuck force is not enough and clamping workpiece.When the hole in the car, the self-aligning claw configured by the power chuck is not replaced in time, so that the clamping force is not uniform, and the clamping block positioning datum is not corrected in time.
(3) the clamping force of the clamp is too large, so that the ring will become prismatic, if too small, the workpiece is not tight, easy to slide.
3.2.2 Out of tolerance of wall thickness and asymmetrical chamfering
(1) The radial swing of the spindle of the machine tool is large, and the coaxiality of the spring chuck is not good, the fixture is not installed correctly, and the spindle is not coaxial, the vibration of the chuck or fixture or the clamping workpiece is improper, the clamping claw or the workpiece has dirt, and the geometric shape of the clamping surface is too large.
(2) The uneven wall thickness and serious eccentricity of the blank also make the uneven resistance and error in cutting and produce the wall thickness out of tolerance.
(3) When the aperture is divided into rough and fine machining twice on the multi-tool semi-automatic lathe, if the cutting depth of the rough lathe is too small and the black skin is not cut off completely or the cutting depth is not enough, the black skin will appear in the fine lathe, which makes it easy to appear large wall thickness difference here.
3.2.3 The variation of the external surface busbar to the base end face inclination is out of tolerance
(1) The vertical and horizontal tool rest of the lathe is not vertical, resulting in excessive wear gap and cutter deviation, spindle skew or axial movement.
(2) The blank itself is SD out of tolerance or leaves black skin to make the workpiece sloshing reproduce the phenomenon, or because the allowance is too small to correct.
(3) the end face of the process is scratched or there is dirt in the support surface of the chuck so that the clamping workpiece is not correct.
(4) the process of processing is not qualified, after unloading no mark reloading processing, vibration ambassador SD big.
(5) weak or because the workpiece positioning clamping workpiece surface such as burr, depression, when cutting tool just cut into the workpiece, and mobile for workpiece, the clamping ring for small, small clamping surface, the length of the ring is holding general for over a third of the total width, if less than a third, when multi-tool semi-automatic lathe processing, often at turning ring tilt, easily damaged when turning tool.
⑥ Fixture adjustment is improper or claw wear, workpiece clamping method is improper, positioning is inaccurate, so that the workpiece installation skew.
3.2.4 Out of tolerance in end face flatness and width variation of inner (outer) ring
(1) The tool is not installed correctly or fastened, the end turning tool is worn or damaged, so that the end face of the car is not smooth and uneven.
(2) the tool rest and guide rail are not vertical, loose plug iron is also easy to produce concave and convex phenomenon.
The forging blank end face concave center, uneven, uneven hardness of the material also directly affects the workpiece VBS(VCS).
3.3 Poor surface quality
Specific performance is: the surface roughness is large, the processed surface residual blank black skin, scratch, vibration, burn, burr, chip marks and so on.
(1) Insufficient processing allowance or irregular shape of the blank, so that the black skin remains after processing.
(2) the tool holder reciprocating is not allowed to abdicate or the jig is not corrected and shaking, so that the tool scratches the processed surface.
(3) improper selection of tool materials, bad grinding edge, edge shape, Angle is not correct, the edge surface is not smooth and smooth, and even the edge has defects, scratches and vibration.The knife is too deep, the cutting force is too large and the vibration is too large or the dull car, the chamfering blade is not grinded properly, the operation is wrong, and the sharp burr, burr and surface defects appear after the blunt grinding is not replaced in time.
(4) tool chip removal is poor, chip winding workpiece, tool and chuck, coolant pouring is not good or not poured in, not only affect the surface quality, serious will cause burns.
The machinability of the material is not good, the hardness and softness are not equal, which causes the vibration and the wear of the tool to produce the accumulation of debris, stick the knife, gnaw the knife and hit the knife phenomenon and scratch the workpiece has been processed surface.
The rigidity of machine tools and fixtures is insufficient, and the selection of machine tool cutting parameters is improper, resulting in vibration in cutting.
The processing of the ring in the process of transportation in the sequence of the collision, clipping, scratch.
In the cutting process, the clamping force is too small or the clamp is loose, damage the clamping surface;When the tool contacts the workpiece fast forward, it collides or the cutting force is too large and the car is stuffy, resulting in eating the knife, gnawing the knife, collapse and scrap.
In short, in the process of turning processing, due to the influence of above factors make the processing of ring can not meet the various technical requirements provided by process, can be based on the analysis of all kinds of quality problems, find out the causes of waste, types, and a targeted improvement measures, improve the operating methods and processing technology, in order to achieve good quality and high yield, improve labor productivity and economic benefits.