No abstract

Preliminary study on slicing technology and design theory of slicing cutter shows that there is deviation between the machined tooth surface and the theoretical tooth surface, called theoretical machining error. This deviation is affected by cutter parameters and machining parameters. To improve machining accuracy, a suitable combination of parameters should be ascertained. On the other hand, interference between major flank face of the cutter and machined tooth surface of the workpiece could occur with inappropriate parameters. In addition, the constraint conditions of enough addendum thickness and no top cut also raise a claim to parameter optimization. For this purpose, the mathematical model of theoretical machining error is built. The judgment method of interference is proposed. The mathematical discriminants of enough addendum thickness and no top cut are presented. On this basis, the selectable ranges of parameters are determined by the constraint conditions. Then, orthogonal experiment is carried out to select an optimal combination of parameters by analyzing the theoretical machining error. Machining experiment is performed with the selected parameters. The results prove that the proposed optimal selection method is effective and applicable.

In order to optimize the processing parameters of slender rods and achieve high-precision machining, a method of straightness prediction of centerless grinding based on PCA and Markov is proposed. A straightness measuring device for slender rod is developed to collect data. The accumulated straightness data is divided into typical processing conditions. The parameters that affect the straightness of centerless grinding of slender rod are analyzed based on PCA. According to the correlation between the parameters and the degree of influence on the straightness, the construction of the processing conditions is further simplified. On this basis, the straightness prediction model based on PCA and Markov is established to predict the processing conditions of centerless grinding of slender rods. Taking the centerless grinding of the piston rod of a hydraulic cylinder as an example, the machining experimental research is conducted. The predictive value is compared with the actual measured value, and the result shows that the average error rate is 3.94%, which indicates the effectiveness of the prediction method and meets the needs of actual production. This study provided technical support for parameters optimization of centerless grinding of slender rods parameter optimization and high-precision machining.

Aiming at the quality control problems in the discrete manufacturing process of large and superlarge equipment, which cannot meet the urgent needs of production, a quality control method based on big data and pattern recognition is proposed. A large amount of data is collected through the test equipment developed in the discrete manufacturing process; a database of typical working conditions and an information tracking system relying on the cloud platform were formed. The working conditions were divided by the principal component analysis (PCA) and improved K-means algorithm. The Markov prediction model predicts the working conditions, recognizes the pattern with typical working conditions, regulates the processing parameters, and achieves quality control. Taking the quality control of the hydraulic cylinder manufacturing process above 5 m as an example for experimental verification, the experiments indicated that working conditions can be automatically identified and classified through pattern recognition technology. The process capability index Cpk increased from 0.6 to 1, which proved the effectiveness of quality control and the improvement of processing capabilities.

For the technical problems of slender rod straightening quality control in the mechanical industry, a straightening quality control method for slender rod based on digital twin is proposed. According to the characteristics of the slender rod straightening process system, straightness detection device for slender rod suitable for production site is developed. Combined with the straightening process of the slender rod, straightening stroke model is given. Straightening quality control system for slender rod is established based on digital twin technology. Taking the piston rod of a large hydraulic cylinder as an example, straightening quality is controlled. The result shows that the theoretical calculation error rate of the straightening stroke is less than 0.5%. Straightness data of piston rod with quality control system is compared with straightness data of piston rod without quality control system. The result shows that the straightness consistency of the piston rod by quality control is good, and it is controlled within the range of 0-0.5mm. Straightening pass rate increased from 30% to 100%. This proves straightening quality control system for slender rod based on digital twin is effective. It can meet the needs of actual production. This study provides technical support for the optimization of slender rod straightening process parameters and high-precision machining.