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machining time, machining quality, machining cost<br />

and other especial machining tools or fixtures[6].<br />

Because LMU includes eight elements, and each<br />

element has much different information, through<br />

combining different information of each element, many<br />

LMU-s will be produced and LMU model database will<br />

be set up. Thus, when designing the LMP, designers only<br />

choose the appropriate LMU-s according to the<br />

manufacturing process of a complex part from LMU<br />

model database, in which each LMU has been designed<br />

and defined, so the LMU information of LMP is<br />

relatively static[7]; after choosing the appropriate LMU,<br />

designers should evaluate and compute the machining<br />

time, machining quality, machining cost and point out<br />

the especial machining tools or fixtures for this LMU,<br />

and these information are dynamic, because they are<br />

designed according to this part[8]. The design of LMP is<br />

shown in Fig.1.<br />

part family<br />

geometric<br />

feature<br />

CAD information of<br />

part<br />

CAPP information<br />

of part<br />

LMU(i)<br />

material<br />

type<br />

rough type<br />

Time<br />

requirement<br />

of the LMU<br />

LMU model<br />

database<br />

dimension<br />

range<br />

machining<br />

method<br />

Design LMU<br />

Design LMP<br />

i from 0 to N-1<br />

Cost<br />

requirement<br />

of the LMU<br />

Equipment<br />

demands<br />

Total restriction and weight of time<br />

precision<br />

grade<br />

production<br />

type<br />

Manufacturing<br />

process knowledge<br />

database<br />

Order form<br />

information of<br />

part<br />

Quality<br />

requirement<br />

of the LMU<br />

Fixture<br />

demands<br />

Tool<br />

demands<br />

complex part, and is the mapping result between PMU<br />

and networked manufacturing sub-tasks (LMU-s). EMP<br />

is corresponding to LMP. It is a sequence of several<br />

PMU-s, and includes the detail manufacturing resources<br />

information of PMU-s. The mapping process is shown in<br />

Fig.2.<br />

The 1 st LMU<br />

dynamic<br />

information<br />

The 1 st PMU<br />

Detail resource<br />

information<br />

The 2 st LMU<br />

dynamic<br />

information<br />

The 2 st PMU<br />

Detail resource<br />

information<br />

LMP<br />

EMP<br />

The n st LMU<br />

dynamic<br />

information<br />

Subtask——Manufaturing unit<br />

The n st PMU<br />

Detail resource<br />

information<br />

Networked<br />

manufacturing<br />

task<br />

Mapping<br />

Networked<br />

manufacturing<br />

resource<br />

Fig.2 The mapping process of logical manufacturing tasks and<br />

For example shown in Fig.3, if a physical<br />

manufacturing unit marked as PMU1 accepted a<br />

manufacturing order of a complicated part, after<br />

analyzing the process of this part, process planners<br />

decompose the whole task to N+1 sub-task in considering<br />

itself resources. Among these sub-tasks, two sub-tasks<br />

marked as LMU (0) and LMU (N) can be completed by<br />

PMU1. For other manufacturing sub-tasks, the<br />

cooperative PMU-s should be deployed in considering<br />

the total running time, cost and the total manufacturing<br />

quality.<br />

LMU(0) LMU(1) LMU(2) LMU(N-1) LMU(N)<br />

Total restriction and weight of cost<br />

Total restriction and weight of quality<br />

PMU1<br />

PMU3<br />

PMU2<br />

PMU3<br />

PMU1<br />

Fig.1 Designing flow of LMP<br />

PMU4<br />

PMU4<br />

PMU4<br />

C. Information model of networked manufacturing task<br />

So, for a complex part, which has N manufacturing<br />

sub-tasks, the information model of the whole<br />

manufacturing task is described by the following formula:<br />

LMP=<br />

{ LMU(0),<br />

C , T , Q , F,<br />

E ; LMU(1),<br />

C,<br />

T,<br />

Q,<br />

F,<br />

E;<br />

⋅⋅⋅⋅;<br />

0 0 0 0 0<br />

1 1 1 1 1<br />

⑴<br />

LMUN ( −1),<br />

C , T , Q , F , E }<br />

N−1<br />

N−1<br />

N−1<br />

N−1<br />

N−1<br />

Where: C<br />

i, Ti<br />

, Qi<br />

are the cost, time and quality<br />

restrictions for finishing the LMU (i)<br />

; E<br />

i<br />

and F i<br />

are<br />

the requirements for especial equipments and fixtures; i<br />

is an integer, i ∈[ 0, N −1]<br />

.<br />

Ⅲ. FORMULATION FOR COMPLICATED PARTS<br />

A. Problem description<br />

Definition 4: Executive manufacturing process (EMP)<br />

expresses the whole practical manufacturing process of a<br />

PMU5<br />

PMU6<br />

PMU6<br />

PMU5<br />

Fig.3 The problem description of networked<br />

manufacturing resources optimization deployment<br />

B. Mathematics model<br />

1) Selection fields of PMU and EMP<br />

For a complicated part, after designing the LMP,<br />

according to the detail information of each LMU,<br />

PMU-s that can complete this LMU will be selected<br />

out and these PMU-s are called as PMU subset. The<br />

mapping result for the i -the subtask— LMU (i)<br />

in<br />

LMP is marked as:<br />

G { PMU( i,0)<br />

, PMU(<br />

i,1 ),<br />

⋅⋅⋅,<br />

PMU(<br />

i,<br />

m −1 )}<br />

⑵<br />

i<br />

=<br />

i<br />

202

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