Unfolding and blanking of ventilation pipe processing: In ventilation engineering, the shapes of pipes and parts made of metal and non-metallic sheets are various, and some parts must be processed and fabricated by the basic method of unfolding and blanking. The so-called unfolding refers to laying the surface of pipe fittings on the sheet according to the actual size according to the requirements of the pipe fitting construction drawing (or setting out drawing). The drawn figure is the unfolding drawing, and the quality of the unfolding drawing is good or bad, It directly affects the quality of spiral air duct and components and the use efficiency of materials.
Steps of unfolding blanking: the basic steps of unfolding blanking are: getting familiar with graphics, shape analysis, finding the real length of a straight line or the real shape of a plane, determining the unfolding method and drawing the unfolding diagram.
Be familiar with the drawings. Before spreading and blanking, first of all, be familiar with the construction drawings carefully, understand the contents of the pipe fittings or components to be spread, the position of the ventilation project, the pipe fittings to be connected, the size of its dimensions on the drawings, and the material to be used. For complex pipe fittings and components, it is necessary to read and analyze the construction drawings repeatedly and carefully. All U-shapes must be understood. If the drawings are wrong or cannot be understood or the design is unreasonable, it should be reported to the relevant departments.
Shape analysis The ventilation pipe fittings and components in ventilation and air conditioning engineering are all composed of geometric figures. The purpose of shape analysis is to decompose complex geometric figures into simple geometric figures. Through decomposition, you can find the appropriate expansion method. Generally, the parts to be expanded are shells, which include plane shells and curved shells.
1) Plane shell: it is a shell formed by a group of planes, mainly including prismatic and pyramidal shells. The former is parallel to each other, while the latter is rich in intersection. Generally, according to the number of prisms, there are three prism, four prism and three prism, four pyramid. Regular prism shell: the bottom is regular polygon, and the edge is perpendicular to the bottom plane. Regular pyramid shell: the bottom is a polygon, and the projection of the cone is coincident with the center of the regular polygon at the bottom, otherwise it is a conical shell. After sectioning, various sections of the shell can appear. The characteristics of prismatic shells (truncated bodies) are that the edges of different projection planes are parallel to each other or intersect at a point respectively. The feature of pyramid shaped shell (truncated body) is that the projection of each edge intersects at a point. The extended lines of the four edges of a polyhedral shell do not intersect at a point.
2) Curved shells: shells with curved surfaces or both are called curved shells. Curved shells can be divided into rotating or non rotating shells.