Computer-generated flat-pattern development of heating, ventilating and air-conditioning ductings

Abstract

The production of heating, ventilating and air-conditioning (HVAC) ducts is a common production activity in the sheet metal industry. When part of the duct involves transition elements, the development of the transitional surface to form the flat pattern is often accomplished laboriously by manual drafting techniques. In this paper, algorithms are described that can be used for automatically generating these flat patterns for several classes of HVAC ducts. The algorithms have been implemented on a PC through interfacing a family of c-programs with the Autocad drafting and design system. The c-programs perform the numerical calculations rapidly while Autocad is used mainly for the user interface and for displaying the flat patterns. Cardboard models were constructed from the drawings of the generated flat patterns to verify the correctness of the algorithms.