Selection of the hottest inner hole measuring tool

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Selection of measuring tools for inner holes the machining and measurement of holes are becoming increasingly important in total quality control. On the one hand, the rapid improvement of manufacturing accuracy of cylindrical machining puts forward corresponding requirements for hole machining. On the other hand, because the measurement of holes is much more difficult than cylindrical measurement, it is the bottleneck in mass production, especially the measurement of deep holes, threaded holes, spline holes, etc

statistical process control (SPG) is used in modern production to adapt to the production process with tight tolerance requirements. At this time, the measured value not only reflects the "qualified" and "unqualified" of the machined parts, but also has the dual role of monitoring working conditions, guiding production and recording product quality

the traditional stop/go gauge can not play the above role, because it can not provide data information and transmit it to the computer

air momentum meter is an effective high-precision aperture measurement method, but it is more suitable for stable machining process, and sometimes it is difficult to adapt to the field working environment of mass production. After conversion, it can have digital display and output, so it can also be used for statistical process control. However, its volume becomes too large and its cost is greatly increased

height measuring instruments and coordinate measuring machines can also be used to measure holes, but not only the measurement cost is high, but also the efficiency is unsatisfactory. Compared with their excellent performance in measuring the relationship between holes, using them to measure holes in production does not give full play to their strengths

inner diameter dial indicator is the most commonly used inner hole measuring tool. When measuring deep holes or small batches of workpieces, it has excellent applicability and low investment

when using the bore gauge, if it is a comparative measurement, there are two items that need special attention. The first is the accuracy of calibration. Usually, only one calibration is provided for each segment. The other is the linearity of measurement. These two items are important indicators that affect the measuring performance of measuring tools

in contrast, the performance of the digital inside diameter dial indicator is better. Because it can obtain the minimum value in one operation, that is, the aperture value, while the traditional inside diameter dial indicator often needs several operations to read the accurate aperture value. Therefore, it has become an effective means in measuring cylinder diameter of automobile engine. Now, the inner diameter dial indicator of carbon fiber measuring rod can measure%2m deep hole

the inside diameter micrometer is probably the most widely used means of hole diameter measurement, which is commonly used for the measurement of 1 ~ 300mm hole diameter. There have been many changes in the type of inside micrometer: 3. Mechanical and electronic after sample crushing; There are two-point and three-point forms; There are micrometer screw type and pistol push type. Some of them have reached the repeated measurement accuracy of 1 m and the measurement accuracy of 2 ~ 3 m

several factors that users should pay attention to when considering the accuracy of measuring tools are: resolution, which should generally be about 1/0 of the tolerance. The repeated accuracy of measurement refers to the range of data inconsistency after repeated measurement for several times. The reproduction accuracy is the variation range of measurement data obtained by different people. In these sense, the three-point probe push type inner hole gauge with digital display fully meets these selection requirements. First of all, it uses a constant measuring seat design to make the measuring force thinner, eliminating the possible impact of manual operation during screw micrometer. In addition, when the hole is oblate or triangular (the shape of most holes after machining is between the two extreme shapes), the reading consistency of two-point measurement becomes poor, while the result of three-point measurement better reflects the size of the hole (neither the maximum nor the minimum)

measurement when the inner hole is in the shape of flat circle or unequal edge "triangle". Now, the digital display decimeter is a non-standard measuring tool which is suitable for large tension card and specially designed probe. It plays an important role in the measurement of deep hole, thread (including ball raceway) and spline hole

from the perspective of measurement reliability, the selection of measuring tools should consider the requirements of application, including accuracy, environment, processing mode, etc. the correctness of measurement results depends on comparison and identification. One of the effective identification methods is to compare with the measurement results of the instrument whose roundness measurement can directly affect the final results

the above-mentioned resolution, repetition accuracy, reproduction accuracy and calibration accuracy are several technical indicators for evaluating the performance of measuring tools. In addition, the convenience of use, the size of one-time investment, subsequent maintenance and verification costs are undoubtedly factors to be considered when selecting measuring tools. (end)

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