It can be said that the processing difficulty of automatic equipment parts completely depends on the dimensional accuracy of production drawings. General parts machining accuracy requirements have a lot of, the following understanding of machining accuracy requirements concept, let’s take a look
In the field of machining, the concept of dimensional accuracy requirements on production drawings can be divided into three categories. The first is the position accuracy. It refers to the conformity degree between the actual position and the ideal position of the point, line and surface in the machining of mechanical parts. According to GB / t1182-1996, there are 8 items to evaluate the position accuracy, including parallelism, perpendicularity, inclination, coaxiality, symmetry, position, circular run out and total run out. Position accuracy is controlled by position error, and the position tolerance of each item is divided into 12 Accuracy grades.
The second is dimensional accuracy: it refers to the degree that the actual value of dimensions such as diameter, length and surface distance of mechanical parts is close to the ideal value. Dimensional accuracy is controlled by dimensional tolerance. Dimensional tolerance is the allowable variation of part size in machining. When the basic dimensions are the same, the smaller the dimensional tolerance is, the higher the dimensional accuracy is. According to the national standard GB / t1800.2-1998, dimension tolerance is divided into 20 tolerance grades, namely IT01, it0, it1, it2, it17 and it18. It stands for standard tolerance (it is the abbreviation of international tolerance in English). The grade code of tolerance is expressed in Arabic numerals. From IT01 to it18, the accuracy decreases and the tolerance value increases in turn.
Finally is the shape accuracy: refers to the mechanical parts processing line, the surface actual shape and the ideal shape conformity degree. According to GB / t1182-1996, there are six items to evaluate the shape accuracy, including straightness, flatness, roundness, cylindricity, line profile and surface profile. Shape accuracy is controlled by shape tolerance. Except for roundness and cylindricity, all shape tolerances are divided into 12 precision grades. Grade 1 is the highest and grade 12 is the lowest.
The above is the requirement of machining accuracy. Thank you for sharing!
ken. tang@chengcg.com
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