Precision testing items and common tools of the ho

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CNC machine tool accuracy testing items and common tools

-- advanced technology of Renishaw company in the UK

1 preface

for every factory, the purchase of CNC machine tools is a considerable investment. In order to make the invested equipment play a key role in production and ensure that qualified parts are processed, it is very important to recover the cost as soon as possible

experience shows that more than 80% of machine tools must be debugged on site before they can meet their technical indicators. Therefore, during the acceptance of new machine tools, verification should be carried out to ensure that the machine tools can meet their technical indicators and expected quality and efficiency at the beginning of installation

in addition, experience also shows that 80% of the machine tools that have been put into production are in abnormal super performance working conditions after a period of use, even exceeding their potential bearing capacity. Therefore, the new machine tool usually needs to be verified again after half a year of use, and then it can be verified once a year. Regular detection of machine tool errors and timely correction of screw pitch and reverse clearance can effectively improve the accuracy of machine tools in production and use, improve the processing quality of parts, avoid waste products, and greatly improve the utilization rate of machine tools. In short, revealing the problems of machine tools in time can avoid the loss of machine tool accuracy and destructive use of machine tools

with the further promotion and application of numerical control technology, more and more numerical control machine tools use their own probe system to detect the size of workpieces and tools and digitize copying. You should know that the realization of the above functions is closely related to the accuracy of the machine tool itself. If the accuracy of the machine tool is not calibrated regularly, it is impossible to complete the above work accurately

Renishaw ML10 laser interferometer linear displacement measurement software can provide data analysis according to the following standards: bs4656 British three measuring machine standard; Bs3800 British machine tool standard; ISO international standard; Vdi/dgq 3441 German Institute of engineers machine tool standard; VDI 2617 German Society of engineers three measuring machine standard; Nmtba American machine tool association standard; GB Chinese national standard; ASME b89.1.12m American Society of mechanical engineers standard; ASME B5.54 American Society of mechanical engineers standard; E60-099 French standard; Jisb2330 Japanese national standard

2 advanced technology of Renishaw company in the UK

Renishaw company in the UK is a world-wide multinational company specializing in the design and manufacture of high-precision testing instruments and equipment. The main products are CMM and NC machine tool probe, laser interferometer, ball bar instrument, etc., which provide a series of quality assurance means for the mechanical manufacturing industry, including pre sequence (laser interferometer and ball bar instrument), pre sequence (workpiece probe and tool setting probe for NC machine tool) and post sequence (probe and configuration for CMM). All of her technologies and products are designed to ensure the accuracy of CNC machine tools, improve the performance of CNC machine tools, improve the efficiency of CNC machine tools, ensure and improve the machining accuracy and quality of machine tools in CNC machine tool manufacturers, and expand the market of finished products

2.1ml10 laser interferometer

Renishaw ML10 laser interferometer provides a high-precision instrument for machine tool verification. It has high accuracy, reaching ± 1.1 ppm (at 0 ~ 40 ℃) for tightening bolts and other steps, and has a large measurement range (linear measurement length of 40m, optional 80m). It is usually used to measure the elongation of materials with fast measurement speed (60m/min) and high resolution (0.001 μ m) , good portability. Because renishao laser interferometer has the function of automatic linear error compensation, it is convenient to restore the accuracy of the machine tool, which is more popular with users

in order to make you further understand the unique advantages of ML10 laser interferometer in detecting the accuracy of CNC machine tools, the following focuses on the application of ML10 laser interferometer in accuracy detection

(1) geometric accuracy detection can be used to detect straightness, verticality, pitch and yaw, flatness, parallelism, etc

(2) the detection and automatic compensation of position accuracy can detect the positioning accuracy, repeated positioning accuracy and micro displacement accuracy of CNC machine tools. Using renishao ML10 laser interferometer can not only automatically measure the error of the machine, but also automatically compensate its linear error through RS232 interface, which saves a lot of time than the usual compensation method, and avoids the operator error caused by manual calculation and manual NC typing. At the same time, the compensation points on the measured axis can be selected to the greatest extent, so that the machine tool can achieve the best accuracy, In addition, the operator does not need to have knowledge of machine tool parameters and compensation methods

at present, the compensation software available are FANUC, Siemens 800 series, UNM, Mazak, Mitsubishi, Cincinnati acramatic, Heidenhain, Bosch, Allen Bradley

(3) detection and automatic compensation of indexing accuracy of NC turntable now, the automatic measurement of rotation axis can be carried out by using ML10 laser interferometer and rx10 turntable benchmark. It can automatically measure any angular position at any angular interval, and its accuracy is ± 1. New international standards have recommended the use of this new technology. Compared with the traditional method of using autocollimator and polyhedron, it not only saves a lot of measurement time, but also obtains a complete accuracy curve of the rotating shaft, knows every detail of its accuracy, and gives the statistical results processed according to the relevant standards

(4) detection and automatic compensation of double axis positioning accuracy Renishaw double laser interferometer system can synchronously measure the positioning accuracy of large gantry mobile CNC machine tools driven by double servo, and can automatically compensate the linear errors of two axes through RS232 interface

(5) dynamic performance detection of CNC machine tools using Renishaw dynamic characteristic measurement and evaluation software, laser interferometer can be used for machine tool vibration test and analysis (FFT), dynamic characteristic analysis of ball screw, response characteristic analysis of servo drive system, dynamic characteristic analysis of guide rail (low-speed crawling), etc

2.2qc10 ball club instrument

in the accuracy detection of CNC machine tools, QC10 ball club instrument and ML10 laser interferometer are two complementary instruments, which are indispensable. ML10 laser interferometer focuses on testing the accuracy of the machine tool; QC10 ball and rod instrument is mainly used to determine the cause of the loss of accuracy of the machine tool and diagnose the faults of the machine tool. However, compared with ML10 laser interferometer, QC10 Club instrument has not been understood by the majority of users. Therefore, the following will focus on the principle, function and application of QC10 Club instrument in detection

2.2.1 what is a ball instrument

renishao QC10 ball instrument is a tool for rapid detection of two axis linkage accuracy and machine failure analysis of CNC machine tools. It is composed of a high-precision displacement sensor installed in a retractable fiber rod. The sensor includes two coils and a movable inner rod. Its working principle is similar to that of the spindle bearing using LVDT technology. D) HP has also reached a cooperation with BASF on whether the height width ratio of the lubricating grease in the box is appropriate; Displacement sensor. When its length changes, the inner rod moves into the coil, the induction coefficient changes, and the detection circuit converts the inductance signal into a resolution of 0.1 μ M displacement signal is transmitted to PC through interface. Its accuracy is measured by laser interferometer to ± 0.5 μ M (at 20 ℃)

when the machine tool goes round with the length of the ball bar instrument as the radius according to the predetermined procedure, the QC10 sensor detects the change in the direction of the moving radius of the machine tool. Renishao QC10 analysis software can quickly separate the straightness, perpendicularity, repeatability, reverse clearance, whether the proportion of each axis is matched and the servo performance of the machine tool from the change in the radius

2.2.2 main functions

(1) rapid calibration of the accuracy grade of the machine tool. By detecting the machine tool with a ball bar instrument at different feed speeds, the operator can select the feed speed that meets the accuracy requirements of the workpiece to process, thus avoiding the generation of waste products

(2) rapid diagnosis and analysis of machine tool faults and problems. The ball club instrument can quickly find and analyze the problems of the machine tool. It can mainly check the reverse difference, lead screw back clearance difference, servo gain mismatch, perpendicularity error, lead screw cycle error and other performance. For example, after the machine tool has a collision accident, the ball club instrument can be used to detect and quickly tell the operator the accuracy of the machine tool and whether it can be used continuously. The ISO standard has stipulated the method of testing the accuracy of machine tools with ball and rod instruments

(3) it is convenient for the maintenance of the machine tool. The ball instrument can tell the user the accuracy change of the machine tool, so as to remind the maintenance engineer to pay attention to the problems of the machine tool and carry out preventive maintenance, so as not to cause major failures

(4) shorten the development cycle of new machine tools. The influence of the selection of machine tool lubrication system, servo system, bearing pair, etc. on the accuracy and performance of machine tools can be analyzed by using ball bar tester. In this way, the original design can be changed according to the test situation, so the development cycle of the new machine tool can be shortened

(5) convenient machine tool acceptance test for machine tool manufacturers, the ball bar instrument can be used to quickly carry out the factory inspection of the machine tool to check whether its accuracy meets the design requirements. The ball bar tester has been recommended by international machine tool inspection standards such as iso230 and ANSI B5.54. For the machine tool user factory, the ball bar instrument can be used to conduct the machine tool acceptance test to replace the NAS specimen cutting, or the specimen can be cut after the machine tool is tested with the ball bar instrument

2.2.3 working accuracy detection

qc10 ball and rod instrument is a kind of instrument that can quickly (10 ~ 15min), conveniently and economically detect the linkage performance of two axes of CNC machine tools, and can be used to replace NAS specimen cutting with working accuracy

about the author: Zhou Hanhui, room 2302, Nanyin building, No. 2, North East Third Ring Road, Beijing, renishao Company Beijing office, zip code: 100027 (end)

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