Development of Surfaces

Development of surfaces

“The development of surface of an object means the unrolling and unfolding of all surfaces of the object on a plane.”

“If the surface of a solid is laid out on a plain surface, the shape thus obtained is called the development of that solid.”

In other words, the development of a solid is the shape of a plain sheet that by proper folding could be converted into the shape of the concerned solid.

In industrial world, an engineer is frequently confronted with problems where the development of surfaces of an object has to be made to help him to go ahead with the design and manufacturing processes. For example, in sheet metal work, it plays a vital role, thus enabling a mechanic to cut proper size of the plate from the development and then to fold at proper places to form the desired objects, namely, boilers, boxes, buckets, packing boxes, chimneys, hoppers, air-conditioning ducts etc.

Knowledge of development is very useful in sheet metal work, construction of storage vessels, chemical vessels, boilers, and chimneys. Such vessels are manufactured from plates that are cut according to these developments and then properly bend into desired shaped. The joints are then welded or riveted.

Principle of Development:

Every line on the development should show the true length of the corresponding line on the surface which is developed.

Methods of Development:

(a) Parallel-line development

(b) Radial-line development

(d) Approximate development

Parallel-line Method: It is used for developing prisms and single curved surfaces like cylinders, in which all the edges/generation of lateral surfaces are parallel in each other.

Radial-line Method: It is employed for pyramids and single curved surfaces like cones in which the apex is taken as centre and the slant edge or generator as radius of its development.

Triangulation Method: It is used for developing transition pieces.

Approximate Method: It is employed for double curved surfaces like spheres, as they are theoretically not possible to develop. The surface of the sphere is developed by approximate method. When the surface is cut by a series of cutting planes, the cut surfaces is called a zone.

EXAMPLES OF DEVELOPMENT OF SECTIONS: