Application of the hottest CAD function in CMM

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The application of CAD function in CMM

this paper briefly expounds the use and function of CAD in CMM software

key words: CMM CAD virtual measurement reverse engineering


CMM, as a kind of high-precision general measuring equipment, has a development history of decades. It is more and more widely used in the field of industrial production, and it is also more and more valued by production-oriented enterprises. The introduction of CAD function in CMM software pushes the application field and ease of use of CMM to a new height

taking the CMM measurement scheme of Xi'an Lide measurement equipment Co., Ltd. as an example, the application of CAD in CMM is briefly introduced below

1. Virtual measurement

virtual measurement is to measure the CAD model in the software without the actual workpiece

the measurement software of Xi'an Lide measurement equipment Co., Ltd. has powerful CAD functions. When virtual measurement is required, open the software, select the offline working mode, then import the CAD model to be measured, and map the CAD model to the selected coordinate system to measure. According to the geometric elements to be measured, click the position of the point to be taken on the CAD model with the mouse. At this time, the position of the point to be taken will be displayed on the CAD model. All samples between the two fixtures will get different degrees of tensile deformation and its vector direction. According to the needs of the measured geometric elements, multiple point sampling can be carried out. When the required points are collected and then determined at the midpoint of the point acquisition window, the system will drive the virtual probe to collect points, and draw up the geometric elements to be measured and their graphics

CAD environment of CMM software

virtual measurement can determine various dimensional parameters of CAD models without dimensional data by measuring them. But this is not the main purpose of virtual measurement. The main function of virtual measurement is to serve for automatic measurement programming in offline state

2. Offline programming

CNC CMM improves the efficiency of batch measurement. By programming the measurement of a given workpiece, full-automatic and fast measurement can be achieved

before the CAD function was introduced into the CMM software, the preparation of the measurement program required professionals to program the corresponding drawings. This programming method is more complex to use and requires higher requirements for operators

another method is to use the self-learning programming function of CMM software to automatically generate the measurement program while actually measuring the workpiece. When the same workpiece is measured again, this program can be called for automatic measurement. This method is widely used in the industry because of its simplicity and wide adaptability. However, this kind of programming cannot be separated from the actual workpiece, so it brings many insurmountable shortcomings to the rubber tensile testing machine when testing rubber materials. First, because the programming is inseparable from the hardware environment, it is necessary to turn on the air source supporting the measuring machine to make the measuring function operate normally before programming, which is more cumbersome. Second, programming is inseparable from the workpiece, so you must wait until the workpiece processing is completed before programming, which will reduce the work efficiency and affect production

After the CAD function is introduced into the coordinate machine measurement software, the self-learning programming process can be completed by virtual measurement of the CAD model in the offline state, so the above problems are solved. No matter whether the production is carried out or not, as long as the CAD drawing files designed by the design department are input into the measurement software, programming can be carried out. After the workpiece is processed, the program measurement can be carried out, which greatly improves the production efficiency. The specific method is to open the CAD model of the workpiece to be measured in the CMM software, and then open the self-learning function of the measurement program. After the coordinate system is established, the measurement of the workpiece can be simulated. The system will automatically generate the measurement program

after the programming is completed, you can also call the program in the CAD environment to simulate the measurement, verify the program, find out the wrong measurement path and sampling point in the operation process, and correct the program, so as to minimize the problems that may occur in the actual measurement and ensure the safety in the measurement process to the greatest extent

3. Make the evaluation of positional tolerance more convenient

in the previous three coordinate measurement software, to evaluate the positional tolerance of geometric elements, you must manually input the theoretical position of geometric elements, and then compare it with the actual measured value, so the evaluation of positional tolerance is very inconvenient

when the coordinate measuring machine software introduces the CAD function, the CAD model can be measured in the software. Because the model is designed, the measured value is the theoretical value of geometric elements. After having the theoretical value, the actual workpiece is measured in the corresponding coordinate system, that is, the actual value of the required geometric elements is obtained. In this way, the positional tolerance of the measured geometric elements can be evaluated

in use, it not only saves the trouble of manually entering the theoretical values of geometric elements one by one, but also avoids frequent changes in the coordinate system in order to correspond to the dimensions marked on the drawing. This greatly reduces the labor intensity of operators, reduces the probability of errors, and improves the accuracy and efficiency of measurement

4. CAD output is used for reverse engineering

in the current production and manufacturing, we often encounter such a situation that customers can provide manufacturers with only physical objects without any drawings or CAD data, especially complex models with curves, curved surfaces, etc. in the samples, it is difficult to obtain accurate data through measurement. In this case, the traditional processing method is to use carving or other methods to make a one-to-one mold, and then use the mold for production. This method can not obtain the accurate size drawing of the workpiece, and it is difficult to modify its appearance

reverse engineering is a set of theories proposed to solve the above problems. Reverse engineering refers to the process of generating drawings or various related dimensional data from workpieces, which is relatively different from the traditional process of generating workpieces from drawing data. The introduction of CAD function into CMM software for reverse engineering has greatly expanded the function of traditional CMM for finished product detection

in reverse engineering, firstly, coordinate measuring machine is used to accurately measure the shape of the sample, and then CAD function is used to process the measured data, and finally one or several CAD format data files are generated. For example, the three cycle of Xi'an Lide company consists of two isothermal processes and two adiabatic processes. The coordinate measurement software generates IGS format data, and the functions attached to this software can also be used to convert data between various CAD formats

these data files can be accepted by general cad/cam software systems. With these software systems, data can be modified, or NC machine tool processing method programming can be directly carried out, and finally NC machine tool processing can be guided. These data can also be sliced to guide the laser forming machine for rapid prototyping

reverse engineering can not only make the workpiece enter mass production quickly, but also get the CAD data of the workpiece. With these data, you can use the CMM to detect the produced workpiece to ensure the quality of the product


as a general-purpose measuring machine, coordinate measuring machine has an irreplaceable position in modern industry because of its high measurement accuracy and efficiency, as well as its convenient operation, measurement and many other advantages. The introduction of CAD function will surely bring more space for CMM and make the oil cylinder fall back;. (end)

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