Page 271 - Modular design for machine tools

230 Engineering Design for Machine Tool Joints

Directions of
machining relative to each other
10 q

9

8 7
Mean interface pressure ton/in 2 6 5 4 Equivalent solid 30°

0°
90°
3
60° q
2
Scale-m in
1
0 200 400
0
Deflection normal to joint
Figure 6-9 Effects of machined lay orientation on joint deflection—shaped mild
steel joint (by Thornley and coworkers).

brass and Al alloy, the size of specimen being 1 in bore, 15/8 in height,
8
2
and 2 in cross-sectional area. Although they do suffer from some lim-
itations, the works of Thornley et al. involve much interesting evidence
and thus in the following, some noteworthy results will be stated.
Machined lay orientation. Thornley is credited with being the first
researcher to suggest the importance of the machined lay orientation on
the joint deflection. Although the shaped flat joint made of mild steel
does not show obviously the effect of the machined lay orientation, as
seen in Fig. 6-9, the machined lay orientation is dominant in certain
joints, and thus it should often be taken into consideration.

8
It is worth suggesting the following report for the ease of understanding of the achieve-
ments of Thornley and coworkers, although the report itself is confidential to members
of MTIRA.
Connolly, R., and R. H. Thornley, Research Report No. 13, “The Static Stiffness of Joints
between Machined Surfaces,” The MTIRA, March 1966.