H. Cho et al., A FORMAL APPROACH TO INTEGRATING COMPUTER-AIDED PROCESS PLANNING AND SHOP-FLOOR CONTROL, Journal of engineering for industry, 116(1), 1994, pp. 108-116
A formal approach for integrating Computer-Aided Design (CAD), Compute
r-Aided Process Planning (CAPP), and shop floor control for rotational
components is presented in this paper. It is assumed that this approa
ch will be implemented within the framework of a three level hierarchi
cal CIM architecture that consists of the following levels in the hier
archy: shop floor, workstation and equipment (Joshi et al., 1991). Our
approach to CAPP consists of machining feature identification, defini
tion, classification, representation, and reasoning, provided through
a CAD model of a product. Geometric entities are identified from a Dra
wing Exchange Format (DXF) file. The identified entities form the basi
s for the construction of primitive manufacturing features. The primit
ive features are assembled together based upon the precedence among fe
atures, into a graph, called a feature graph. However, the primitive f
eatures may or may not be manufacturable in terms of depth of cut, too
l geometry, surface finish, and material handling required. Hence it i
s necessary to con vert the feature graph into a manufacturing task gr
aph, which consists of specifications of alternative functional tasks
that are manufacturable. The task graph may be converted into a hierar
chical set of process plans, based on the planning criteria at each le
vel in the control hierachy, to reflect the processing requirements at
each level. The shop planning function decomposes the task graph into
a set of workstation level plans. Each workstation level plan is aggr
egated into a set of equipment level process plans by the workstation
planning function. The equipment level plan is converted into a unique
task sequence by the equipment planning function. This sequence is th
en executed according to specifications by the equipment level executi
on function. Provision of alternative routes in process plans provides
for flexible means of on-line planning and control.