Inch pitch is expressed in terms of how many teeth per inch. Set the caliper to 25.4 mm, align one apex with the thread tip, and the other cusp such as the thread cusp is an inch thread. For example, the tangential thread tip should be a metric thread.The spiral symmetry of the composite symmetry action is based on the line symmetry element. The axis of the helix present in crystallography is denoted by and is referred to as the n-heap nm-type helix.
The basic motion of the spiral rotation corresponding to the nm helix axis is denoted as is the base rotation angle when rotating around the n-helix axis, and the translation amount in T is taken as the screw axis. of the axial basic period. For example, the basic rotation of the spiral rotation corresponding to the axis axis parallel to the direction to restore the crystal structure is to rotate and then perform translation. Before processing, it is first necessary to analyze the drawings of the processed shaft parts to clarify the processing steps, processing contents and technical requirements.
The axial requirements of the shaft parts are not high, mainly due to the high dimensional accuracy and shape accuracy requirements of the journals and the bearing journals. In addition, the coaxiality of the matching journals to the bearing journals must be ensured. The mutual positional accuracy is mainly concentricity and circular runout; geometric accuracy is mainly roundness and cylindricity, and it is required to be controlled within the diameter tolerance range. According to the processing requirements, determine the part processing plan, and develop the CNC machine tool processing route. The shaft parts are generally forged, and the engine crankshaft shaft parts are generally made of ductile iron castings.
Before turning, it is often necessary to arrange the preparatory processing according to the situation. The blanks of the casting and forging should be arranged in accordance with the material and technical requirements before the roughing, to eliminate the stress and improve the structure and cutting performance. The blanks with higher performance requirements should be quenched and tempered after roughing and finishing to improve the comprehensive mechanical properties of the parts. For parts with low hardness and wear resistance, quenching and tempering is often used as the final heat treatment.
