Turning shaft workpiece accuracy analysis

Shaft parts in the turning process, will encounter accuracy and surface roughness mainly the other issues. According to the specific process of turning for analysis.

Mainly the dimensional accuracy of the causes and solutions 1. Because the operator is not careful, measured when the children go awry, or dial it wrong and improper use of the measurement, to carefully and correctly is very important to use the dial , just dial in the carriage handle, the various types of lathe dials are not the same, each small grid scale used the following formula: scale turn a grid pallet screw turning movement distance = distance / dial engraved lines total number of cells (mm) know each grid scale value later, when in use must pay attention because there is a gap between the screw and nut, sometimes turning dials though, but the tools will not necessarily move, and so the gap turn finished before turning movement. Therefore, when in use, the number of cells if the scale turned too far, never allow only a few cells reversed, but to reverse a turn later, and then re-align the scale. (2) there is an error or measuring itself without being put to use measuring tools, you should carefully check and adjust, when used to put positive. 3 due to temperature changes, the change in size of the workpiece during cutting, deformation of the chip, each chip between the respective molecules move against each other, and they move the friction generated when a large amount of heat. In addition, since the chip and the front friction tools, turning tools and the workpiece rear surface of friction generates heat, the heat directly affect up to the tool and the workpiece.

Precision geometry and position of the main reasons mainly the precision 1 causes occurrence of ovality. A. Shaft journal ovality is directly reflected in the work up, if the sliding bearing, then the magnitude and direction when the load is not variable, the spindle neck under load is pressed against the bearing surfaces a predetermined position (between the spindle and the bearing clearance). When the spindle is rotated 90 °, a change in the center of the spindle, so that during one revolution of the spindle has two center position, turning the back there is a change of cut, leaving the workpiece ellipticity. Ellipticity bearing hole of the workpiece has no effect. b. rough uneven margin, plus there is a gap between the spindle and bearings in the cutting process, cutting depth change. c. around the center hole does not match (two center hole at an angle with the workpiece center), the center hole only come into contact with the top side, causing uneven wear axial movement made oval d. former top swing.

Generating the bus is not straight (sterile curved, convex, saddle-shaped) and taper causes a. Lathe spindle axis rail and the mutual position is not correct, in particular in the horizontal. Such as rail bent workpiece convex or concave, rail and the tapered spindle axis is not parallel to produce and so on. b. around the top centerline is not parallel with the bed rail, resulting taper. c. the workpiece temperature, causes the bending axis. For example, in the heavy lathe axis, the temperature rises to a certain time, the workpiece will stretch, but as the distance between centers unchanged, the results could not work because the elongation in the longitudinal direction is bent. Therefore, the long axis of the vehicle, try to lower the temperature, but also must often look back after the top. d. workpiece stress. There is often the stress within the workpiece, the cutting process, due to the plastic deformation of the surface layer, will produce stress, which was the internal stress state of equilibrium inside the workpiece, the workpiece to maintain a certain shape when the lathe work or unloaded from the jig Next, it is necessary deformation. solve this problem, the general aging treatment.

Runout caused by sharp pulsating reasons in the preceding paragraph; center hole is not round or chips and other dirt; course ovality workpiece surface can cause runout.

Mainly the surface roughness of the main one. Lathe less rigid as iron pallet plug loose, drive unbalanced vibrations, of course, is not installed securely lathe will cause vibration, due to vibration caused by the surface roughness is reduced. Turning vibration caused by insufficient rigidity so far as possible use coarse Arbor, projecting a reduced turning length; insufficient rigidity of the workpiece can cause vibration, so the elongated axis turning center rack to be applied, or a folder instead of a two top clamping.

Turning the cutting part geometry parameter is incorrect can be cut according to the workpiece material properties used reasonable and appropriate cutting angle to reduce the surface roughness. 4 due to BUE generation, so that the surface roughness is reduced BUE very strong, cutting the BUE participation, so that the surface appears nap or a tract zoned grooves of the phenomenon, which should be avoided turning production. Combination of the foregoing analysis, the processing should be done early to know early prevention, the problem is nipped in the bud, to improve accuracy of the workpiece to meet the design requirements.