Bearing size and precision

1. Artifacts feet す accuracy and process dimension precision in mechanical manufacturing process theory, the precision and error are two important concepts. Refers to the work piece machining accuracy and ideal of artifacts in accordance with degree. Corresponding to the error and precision, it refers to the processed workpiece and the degree of deviation of ideal artifacts. Therefore, the precision and error is the same problem from positive and negative two aspects above. According to the concept of the precision and error, it is not hard to see the meaning of size precision and size error. Breaking in science and technology theory and practice research, often depending on the need to use these two concepts. Any artifacts are made by raw materials through a series of hot working eventually reaches a certain accuracy requirement. Because of this, the size of the workpiece is closely related to the precision and processing methods, processing equipment; Moreover, each procedure, the workpiece accordingly obtain certain dimensional accuracy. In this way, the workpiece ruler す leads to the concept of process 'す precision accuracy. A process dimension precision, refers to the under certain technological conditions the process to ensure that the work of a dimensional accuracy. Obviously, the size precision of the workpiece and the size of the process accuracy in essence is consistent, process the size of the precision of the size of the labor to express the quantitative accuracy. Also, procedure dimension error and workpiece size error. It seems that evaluation of centerless grinding dimensional accuracy, in fact is the evaluation of the size of the workpiece in centerless grinding accuracy; And the study of artifacts feet す precision, can completely from the process 'す accuracy if the composition of the hand. It is necessary to point out that, for the bulk processing method of centerless grinding, care about is not the size error of a workpiece, but a group of workpiece size error. Feet す error of centerless grinding process is a statistic is the overall size of workpiece under a certain confidence level dispersion. 2. Size error character size error form and many factors, some of these factors, some unknown. No matter what factors can be used, variable value system error and random error constant system error described the three error types. 1) Random error and accidental error and random error probability error and the possibility of error. This error is caused by the many random factors. On the surface, it is about the size, direction and no regularity, but in fact implies a certain statistical distribution. In centerless grinding process, the factors influencing the dimensional precision of random error generally have blank size error, cut into the grinding wheel parts when repeated positioning error, workpiece material properties between uniformity, measurement error, etc. , of course, many find out factors have been identified and +. In the normal grinding, make use of these random factors are small. Impossible, therefore, also it is not necessary to find out these factors one by one, face only master its statistical law. Production practice shows that the size of the random error is general correlation law of miniature bearing cloth. Normal distribution is a continuous random variable theory. It is put forward by gauss, so it is also known as the gaussian distribution, as shown in figure 9 - the graphics 24 by rate theory, the workpiece can be ruler す normal distribution density function of FIG. 9 24 181 normal distribution