Page 237 - Modular design for machine tools

Basic Knowledge of Machine Tool Joints 197

their own stiffness. In short, the relative stiffness of joint surround-
ings to the joint itself is of great importance.
Obviously, by taking the factors summarized above into consideration,
we can design the simple flat joint itself, which can be regarded as a basic
configuration of all the machine tool joints. Thus for each joint, we
should furthermore consider other factors shown, e.g., for bolted and slid-
ing joints, in Table 5-2, and the dominant factors are as follows.

TABLE 5-2 Specified Influencing Factors in Bolted and
Sliding Joints
(a) Bolted joint
Resultant factor:
Bearing area and interface pressure distribution
derived from tightening force
Leading factors
Number of connecting bolts
Locating position and arrangement of connecting bolts
Tightening force of connecting bolt
Flange shape and thickness
Existence of such a taper pin or guide key

Auxiliary factors
Mechanical properties and diameter of connecting bolt
Kinds of connecting bolts—hexagonal head bolt, hexagonal
socket head cap screw and reamer
bolt
Interfacial layer
Thread accuracy of bolt and nut

(b) Sliding joint
Resultant factor:
Bearing area and interface pressure distribution
while being still stand and traveling
Leading factors

Number and allocation of guideways
Kinds of guideways—slideway, hydrostatic guideway, and rolling guideway
Traveling velocity of structural body component
Feed force transmitting mechanism including table feeding device coupling
Gib and keep plate configuration in slideway

Auxiliary factors
Frictional and wear properties of joint materials
Kinds of interfacial layer
Viscosity of lubricants
Structural configuration—separation of bearing way and guide reference way