Page 375 - Design for Six Sigma a Roadmap for Product Development

Theory of Inventive Problem Solving (TRIZ) 345

The design equation is as follows—clearly, this is the coupled design:

{ } [ 0
0 0 0 x ] { }

0
0
x
0
0
DP 1
FR 1
DP 2
FR 2
0

0
0
0
x

FR 3
DP 3
0
0
0
0

0
FR 4
DP 4
0
FR 5
0 0 0 0
x DP 5
0
0
0
0

FR 6 DP 6
However, from the TRIZ standpoint, FR 1 and FR 6 can be viewed as a
technical contradiction because FR 1 requires a large forward force and
FR 6 requires a small forward force. The technical contradiction can be
overcome by applying the contradiction table and 40 inventive princi-
ples. However, if the technical contradiction can be transformed to a
physical contradiction, the separation principles can be utilized to
solve the problem.
In this case, FR 1 and FR 6 require the friction between the upper
roller and the first bill to be both large and small. Physically, two fac-
tors control the friction force between the upper roller and the first
bill: pressure and the friction coefficient. This means that the pressure,
the friction coefficient, or both should be both large and small. Since
FR 1 and FR 6 are not required at the same time, the pressure and fric-
tion coefficient should not be the same all the time. Therefore, the sep-
aration of opposite properties in time, one of the TRIZ separation
principles, can be utilized to overcome the contradiction.
One design solution, making the pressure large and small, is given
in Fig. 9.9. Another design alternative is illustrated in Fig. 9.10. A
Bills Press plate
Pressure
Floor
guide
Pressure
Gate roller
Drive roller
Carriage
pinch
roller
Cam
Upper roller
Figure 9.9 Design of paper isolation mechanism (solution 1).