Abstract
The ram speed of a steam hammer is an important parameter that directly affects the forming performance of forgers. This parameter must be monitored regularly in practical applications in industry. Because of the complex and dangerous industrial environment of forging equipment, non-contact measurement methods, such as stereo vision, might be optimal. However, in actual application, the field of view (FOV) required to measure the steam hammer is extremely large, with a value of 2–3 m, and heavy steam hammer, at high-speed, usually causes a strong vibration. These two factors combine to sacrifice the accuracy of measurements, and can even cause the failure of measurements. To solve these issues, a bundle-adjustment-principle-based system calibration method is proposed to realize high-accuracy calibration for a large FOV, which can obtain accurate calibration results when the calibration target is not precisely manufactured. To decrease the influence of strong vibration, a stationary world coordinate system was built, and the external parameters were recalibrated during the entire measurement process. The accuracy and effectiveness of the proposed technique were verified by an experiment to measure the ram speed of a counterblow steam hammer in a die forging device.
Highlights
The ram speed of a steam hammer reflects the energy of a forging’s deformation and directly affects the forming performance of forging equipment
The ram speed of the steam hammer varies as the number of its use cycles increases, which may deteriorate its performance in forming workpieces
This paper presents a stereo-vision system for measuring the ram speed of a steam hammer
Summary
The ram speed of a steam hammer reflects the energy of a forging’s deformation and directly affects the forming performance of forging equipment. Non-contact methods require the sensors to remain stationary during the measurement process, but the high speed and weight of a steam hammer usually cause a strong vibration. The measurement coordinate system moves in a strongly vibrating environment To solve these problems, a bundle-adjustment-based system calibration method is proposed to obtain accurate calibration results when the calibration target is not precisely manufactured. In contrast with non-contact methods, the proposed technique offers an outstanding advantage of flexible system configuration and insensitivity to strong vibration due to its stationary measurement coordinate system. The accuracy and effectiveness of the proposed method were verified by experiments that measured the ram speed of a counterblow steam hammer in a die forging device This technique can be used in displacement measurement in a vibrating environment with a large FOV.
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