Introduction
The complete surface of an object laid out on a plane is called the development of the surface or flat pattern of the object. ‘Development’ is a term frequently used in sheet metal work where it means the unfolding or unrolling of a detailed object into a flat sheet, called pattern (see Fig. 14.1). The development of geometrical surfaces is important in the fabrication of not only small and simple shapes made of thin sheet metal, but also for sophisticated pieces of hardware.
In the development of a geometric surface, the opening should be determined first. Every line used in making the development must represent the true length of that line on an actual surface.
The knowledge of development of surfaces is essential in many industries such as automobile, ship building, packaging, sheet metal work, etc.
Methods of Development
There are four methods of development. These are:
(i) Parallel Line Method:It is employed in case of prisms and cylinders in which stretch-out line principle is used. Stretch-out is given by the perimeter of the object measured in a plane at right angles to the axis.
(ii) Radial Line Method:It is applied for the development of solids with slant edges like pyramids and cones. Here the true length of the slant edge of the cone or pyramid is taken as the radius of the arc of development.
(iii) Triangulation Method:It is used to develop transition pieces. It is a method of dividing a surface into a number of triangles and transforming them into the development.
(iv) Approximate Method:It is used to develop objects of double-curved or warped surfaces as sphere, paraboloid and hyperboloid.
Only the lateral surfaces of the solids have been developed and shown as presented here, omitting the bases or ends of solids.
Parallel Line Method
The surfaces of right prisms, oblique prisms, right cylinders and oblique prisms are developed by this method. In this method right section and stretch-out line principle is used. Parallel lines, parallel to the axis of the detail, are shown on a view which shows them as their true lengths.
Review the options below to login to check your access.
Log in with your Cambridge Higher Education account to check access.
If you believe you should have access to this content, please contact your institutional librarian or consult our FAQ page for further information about accessing our content.