Determining the regime parameters for the surface cleaning of post-consumer wood by a needle milling tool

摘要

This paper addresses the identified issue of the inefficient use of post-consumer wood (PCW) in the technological wood processing due to its surface contamination. An option to resolve this issue by cleaning PCW in a mechanized manner has been proposed, specifically by using a needle milling tool and selecting the tension value and feed rate. The impact of the tension of needle milling tools before processing on the cleaning depth of the contaminated surfaces of workpieces made from the PCW has been determined. The constructed model of the contact between a needle milling tool and the contaminated PCW surface has made it possible to describe the essence of the cleaning technique involving this tool. It was found that the depth of the layer removed by the needle milling tool’s wire is reduced in proportion to an increase in the distance before cutting is completed. A nomogram has been built to determine a change in the front angle depending on the needle milling tool’s tension value. Knowing the front angle at a certain point of the needle touch on the contact arc enables determining the thickness of cleaning, which is important for practical application, specifically, at a tension of 4.5 mm the thickness of the removed material can equal 3.46 mm. An adequate regression model was derived, the analysis of the coefficients of which showed a significant impact of tension (+0.895) on the depth of cleaning over the feed speed (+0.256). The devised model makes it possible to forecast the thickness of the removed layer to ensure the required cleanliness of the PCW wooden. Practical recommendations on the operational modes of a needle milling machine have been formulated: the feed rate should equal 10‒12 m/min, the tension ‒ 0.5–5.0 mm, which could ensure, depending on the material’s type, hardness, and the kind of PCW surface contamination, the removal of the surface layer with a thickness of 0.4–4.0 mm. A rational tension of the needle milling tool of 2.5 mm has been proposed for industrial application, which ensures the cleaning depth of contaminated surfaces within the range of 1.8–2.2 mm