INTRODUCTION TO AUTOCAD 1
TECHNICAL DRAWING MEC 112 week 1
WEEK (13)
13.0: SURFACE DEVELOPMENT
13.1: Introduction
Many articles such as cans , pipes , elbows , boxes , ducts , hoppers , etc. , are
manufactured from sheet metals.
Generally a template of their original flat shape is firstly produced; this forms an
orthogonal drawing . Also the template includes allowances for bending and seam ,
bearing , in mind the thickness of material used .
Surface development methods:
There are basic methods of pattern development .
-
the parallel line method
the radial line method .
the triangulation method .
choosing a method depends totally on the shape of the product to be produced and can
be seen through examples .
1) Right cylinder
To develop a pattern for a right cylinder , it is important to understand that,
practically , a cylinder is regarded as a multi-sided prism with circle base. To
develop a pattern means to unroll the sheet as shown in Fig.(25)
To develop a pattern , the following steps are to be followed :
1- Draw front and top views of the cylinder .
2- Divide the top view (circle ) into 12 equal parts ( graphically using the appropriate
set square or analytically by dividing the circumference D over 12 π, i.e. , π D /12)
and number them from 1 to 12 .
3- Project the point 1-12 from top view vertically upwards across the front view .
4- Project two lines parallel to the base of the front view from the top side and bottom
side of cylinder towards the right hand side of board .
5- Measure one of the divided parts and step off this length 12-times along the
development base line .
6- Complete the development as shown in fig.106
INTRODUCTION TO AUTOCAD 1
TECHNICAL DRAWING MEC 112 week 1
13.2: TASK (6)