Cylindrical helical gear transmission is a kind of transmission commonly used in mechanical transmission. Cylindrical helical gear is an important basic part, among which involute cylindrical helical gear is widely used in large-scale NC automatic stamping equipment because of its high transmission accuracy, reliable operation, strong bearing capacity and long service life.
Large CNC automatic stamping production line is mainly used in the field of automobile manufacturing and is an important equipment of automobile industry. Due to its performance advantages, it has many advantages, such as automation, high-speed, compounding, stable part quality and so on. As the preferred equipment for domestic and foreign automobile manufacturers and automobile parts suppliers and the necessary equipment for high-grade automobile panels, it is an essential stamping equipment in national economic production. The main drive of large-scale CNC automatic stamping equipment generally adopts involute helical gear, in which the cylindrical helical gear is the main transmission component of the press. The transmission component is easy to wear the cylindrical helical gear and other parts during long-time movement. Especially in the process of machine tool overhaul, when the helical gear of cylindrical helical gear needs to be replaced due to serious wear, it is often necessary to map the cylindrical helical gear. Taking the press with a rated pressure of 2500 t produced by our company as an example, the tooth top circle is 2326 mm and the net weight of a single piece is 4709.8 kg. Due to the large and heavy size of the cylindrical helical gear of the press, the on-site measurement method commonly used in the general overhaul of the press is to measure the helical angle of the cylindrical helical gear, and the helical angle of the cylindrical helical gear β It is a non standardized value and a spatial angle, which cannot be measured directly. The commonly used methods and instruments and equipment include: tooth outer circle hobbing method, cylindrical helical gear tester measurement method, lead meter measurement method and high-precision hobbing machine differential measurement method. The method of tooth outer circle roll printing is suitable for medium and small gears, and the measurement error is large; The measuring accuracy of the cylindrical helical gear tester is high, but it is limited to the bearing capacity of the equipment and the size of the workpiece. It is only suitable for small and medium-sized gears, and it is unable to measure large gears; To measure directly with gear hobbing machine, the differential change gear needs to be preliminarily calculated according to a helix angle value, and then the differential change gear is repeatedly calculated and adjusted according to the measurement deviation. Finally, the accurate helix angle is obtained, and the repeated workload is large.
Some of the above surveying and mapping methods have large workload and low efficiency, some of the surveying and mapping spiral angle accuracy can not meet the use requirements, and some are not suitable for surveying and mapping large-diameter cylindrical helical gears. It is difficult to measure accurately without precision measuring instruments (tooth alignment instrument, guide log, tool display mirror, CMM, etc.).
In view of the few measurement methods of large involute helical gear with pitch diameter of more than 1000 mm, this paper studies a simple and practical measurement method to accurately measure the helix angle of large cylindrical helical gear through common measuring tools such as steel ball, caliper, common normal micrometer, dial indicator and gauge block, and has been verified by practical application.