Research On The Inner And Outer Diameter Measurement Of Large Ring Cylinder Forgings During Forging

Large ring cylinder forgings are the requisite and key components in the field ofnuclear power equipment, petrochemical equipment and coal liquefaction equipment. Thegeometry size of forgings is one of the main basis for rationally deciding the technologyparameters during forging. The parameters are reduction, forging force, forging times, andso on. Knowing the geometry size information of large forging in real time has greatsignificance to improve internal the forming quality of large forgings, improve machiningprecision, raise productivity, save energy, etc.. Therefore, the research on the inner andouter diameter measuring method for the large ring forgings during forging is done in thispaper. And this meauring method can provide guarantee to ensure the forming quality offorgings, improve the utilization rate of materials, reduce the forging cost, improve themarket competitiveness. The main research works are as follows:Through analyzing the forging process of ring cylinder forgings, the inner and outerdiameter measuring principle of ring forgings is researched. Considering the actualsituation at the scene of the forging, the outer diameter measuring system is built based onthe line green laser and CCD camera. On the basis of outer diameter measuring system,the inner diameter measuring system of large ring cylinder forgings during forging is builtbased on the infrared temperature. The inner and outer diameter measuring system canprovide hardware support for measuring the inner and outer diameter of large ring cylinderforgings.The outer diameter measuring model is established based on the spacial geometrictransformation theory of outer diameter measuring points. The meauring model is matchedwith the outer diameter measuring system of large ring cylinder forging. The constraintcondition of the outer diameter measuring model is proposed according to the measuringtheory of single CCD camera. In order to extract the measuring data of green laser stripeon the forgings’ surface, the solving method of diameter meauring model parameters isstudied. Through analyzing the measuring data, the outer diameter solving method of largering cylinder forgings is researched based on the least square theory. And the measurement of outer diameter is realized.The heat conduction characteristic for ring cylinder forgings is studied by applyingthe heat transfer theory. The heat-conduction differential equation of large ring cylinderforgings during forging is established according to the heat conduction characteristic.Combining the definite condition, the inner diameter measuring model of large ringcylinder forgings is built according to the heat-conduction differential equations. Thetemperature of forgings plays an important role in the inner diameter measuring model.But the present accuracy of temperature measuring method is low. So the three-levelinterference filter model is built in this paper. In order to improve the temperaturemeasuring accuracy of the forgings’ surface during forging, the double-wavelengthinfrared temperature measurement system is established based on the three-levelinterference filter. Then, the inner diameter solving method of forgings is studied based onthe forgings’ surface temperature. And the inner diameter measurement is realized.According to the inner and outer diameter measuring method of large ring cylinderforgings proposed in this paper, the experimental study is made using optical measurementpractice platform of the Key Laboratory for Special Fiber and Fiber Sensor of HebeiProvince. The experimental study of ring cylinder experimental workpiece is done whenthe workpiece is heated to1200℃. The outer diameter measuring experiment is madefirstly. The feasibility and precision of outer diameter measuring method is verified bycomparing with the outer diameter measured by calipers. The temperature measuringexperiment is made secondly. The feasibility and precision of temperature measuringmethod is verified by comparing with the temperature measured by infrared thermalimager. Then combining the outer diameter and surface temperature, the inner diametermeasuring experiment is made. And the feasibility and precision of inner diametermeasuring method is verified by comparing the inner diameter measured by calipers. Thisstudy can lay the foundation of measuring outer and inner diameter for the forgings.