A Statistical Approach in the Analysis of Geometrical Product Specification during the Cold Tube Drawing Process

Ladislav Morovic,Maria Kapustova,Jozef Bilik,Michaela Kritikos,Robert Sobota,Daynier Rolando Delgado Sobrino

doi:10.3390/app12020676

Ladislav Morovic, Maria Kapustova + Show 4 more

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https://doi.org/10.3390/app12020676

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Abstract

Cold tube drawing provides higher accuracy compared to hot approaches. The process can be used to reduce the dimensions of tubes, and depending on the reduction size, the wall thickness of these may be subject to changes. In the process, any form of variability provoked by external factors is highly sensitive, given that the resulting tubes are often the final step in tube production. This paper focused on the evaluation of the influence of pre-tube factors on key variables after the drawing process, i.e., the final roundness, outer diameter, and wall thickness of the tubes. For these purposes, a factorial design with fixed factors was implemented. It was also a goal to investigate if the single-pass type of drawing would guarantee good statistical results potentially leading to significant time and financial reductions. The measurements were executed in the machine ZEISS CenterMax. The statistical analysis took place on Minitab 19. The results prove that most factors, and their interactions, significantly impacted the response variables, leading the authors to understand that a single-pass approach would not properly work under the conditions defined for the experimentation. These results also allow for reflection on the causes and necessary measures related to lubrication, technological heritage, and quality that would impact the results themselves.

Highlights

Received: 18 November 2021Over the years, the production of tubes has had a tremendous importance for industry.A clear example of this is the automotive sector, which is the fuel for many European economies such as the Slovak economy
The production of tubes has had a tremendous importance for industry
Some of the most powerful and important methods are those known as factorial designs, which can be found, for example, in [26], where this well-known author recreated and detailed design of experiments (DOE) techniques, with emphasis on such factorial designs, and explained that within these designs, experimental or response variables are investigated through all or part of all possible combinations of the related factors at their different levels, and the results are subsequently analyzed by a technique known as analysis of variance (ANOVA)

Summary

Introduction

Received: 18 November 2021Over the years, the production of tubes has had a tremendous importance for industry.A clear example of this is the automotive sector, which is the fuel for many European economies such as the Slovak economy. In the case of precision steel tubes, these have a narrower tolerance field of diameters as well as wall thicknesses, and in this specific case, there is an increased demand for precise production environments where the correct selection of process parameters and the very construction of the drawing tool play a major role. This cold forming process achieves a higher surface quality and higher dimensional accuracy of tube production compared to hot forming. The principle of cold tube drawing is analyzed in detail in [1,2,3,4]

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