Page 280 - Modular design for machine tools

Engineering Design Fundamentals and Single Flat Joint Characteristics 239

0.4

20

K s mm
Tangential joint stiffness K s , kgf/mm 10 Joint material: BsBM2 max = 2.2 mm 0.2 Microslip d r ,

Joint surface: ground, R
d
r
K s
P
d
P
r

0 0
200 400 600
Normal preload Q, kgf
(b)
Figure 6-15 (Continued)

joint stiffness and microslip with increasing normal preload, when the
joint material and finishing method of the joint are varied. In addition
to the observation reported by Kirsanov, they unveiled further inter-
esting behavior as follows.

1. The joint material and surface finishing have considerable effect on
the tangential joint stiffness. In this context, there is a desirable
surface roughness, at which the joint stiffness shows a maximum
value. Figure 6-16 shows such a characteristic in the case of a scraped
joint, and in fact, the joint stiffness is maximum when the number
2
of contact spots in any 1 in is around 20.
2. The machined lay orientation has also considerable effect on the joint
stiffness, and in general, the perpendicular layout shows larger stiff-
ness than the parallel layout.

Following those studies of Masuko et al., Boothroyd and coworkers
investigated the single flat joint of annular ring type [24, 25] to analyze
the essential feature of structural damping in the wheelhead of a grind-
ing machine. In addition, Burdekin et al. conducted some related stud-
ies on the single flat joint of laminated type [26, 27]. Figure 6-17 is a
firsthand view of a research map regarding the tangential deflection and
microslip of the single flat joint, and summarizing all the observations