zipper machining accuracy

The machining accuracy of zipper refers to the degree to which the actual value of the parameters such as size, shape and mutual position is close to the ideal value after the part is processed. The closer the actual value is to the ideal value, that is, the smaller the machining error, the higher the machining accuracy. The machining accuracy of zipper mechanical parts includes dimensional accuracy, shape accuracy and position accuracy. (1) Dimensional accuracy It refers to the degree to which the actual size of the part is close to the ideal size, which is commonly expressed as dimensional tolerance. According to the national standard GB/T 1800. 1----2009, the standard tolerance is divided into 20 grades, namely ITOI, ITO, IT! to IT18, IT represents the standard tolerance, and Arabic numerals represent the tolerance grade. The higher the number, the higher the tolerance value and the lower the dimensional accuracy. IT01-IT13 are used for mating dimensions, and the commonly used mating dimension tolerances are below IT5; IT14-IT18 are used for non-fitting dimensions. (2) Shape accuracy It refers to the degree to which the actual shape of the part is close to the ideal shape. There are six types of shape tolerances: straightness, flatness, roundness, cylindricity, line profile, and surface profile. (3) Position tolerance It refers to the degree to which the actual position between the surface, axis or symmetry plane of the part is close to the ideal position. There are eight kinds of position tolerance: parallelism, perpendicularity, inclination, position, coaxiality, symmetry, national runout and full runout. Usually, the accuracy achieved by a certain processing method refers to the accuracy that can be achieved under normal operating conditions, which is called economic accuracy. When designing parts, first of all, we should decide which level of precision to choose according to the importance of the size of the parts, and secondly, we should also consider the equipment conditions of our factory and the level of processing costs. In a word, the principle of choosing the mechanical precision of zipper is to choose a lower precision under the premise of ensuring that the technical requirements can be met.