Page 11 - Electric Drives and Electromechanical Systems

Chapter 1 Electromechanical systems 3

gives a considerable number of other features, including data collection and commu-
nication with other machine tools or computers over a computer network. In addition to
the possibility of changing the operating program of a CNC system, the executive soft-
ware of the computer can be changed, which allows the performance of the system to be
modified at minimum cost. The application of NC and CNC technology permitted a
complete revolution of the machine tool industry and the manufacturing industries it
supported. The introduction of electronic systems into conventional machine tools was
initially undertaken in the late 1940s by the United States Air Force to increase the
quality and productivity of machined aircraft parts. The rapid advances of electronics
and computing systems during the 1960s and 1970s permitted the complete automation
of machine tools and the parallel development of industrial robots. This was followed
during the 1980s by the integration of robots, machine tools, and material handling
systems into computer-controlled factory environments. The logical conclusion of this
trend is that individual product quality is no longer controlled by direct intervention of
an operator. Since the machining parameters are stored either within the machine or at a
remote location for direct downloading via a network (see Chapter 11) a capability exists
for the complete repeatability of a product, both by mass production and in limited
batches (which can be as small as single components). Until the 1990’s machining
normally involved the removal of material from the workpiece to form the final object e
this is subtractive machine. Between 1980 and the early 1990’s several processes were
developed that allowed an object to be built up from layers of material, this is termed
additive manufacturing. Additive manufacturing is considered to be a disruptive tech-
nology, due to its flexibility, speed and ability to produce single units at a cost that is very
similar those produced during a long production runs.
A typical CNC machine tool, robot or multi-axis system, whatever its function, con-
sists of several common elements (see Fig. 1.1). The axis position, or the speed con-
trollers, and the machining-process controller are configured to form a hierarchical
control architecture. In this approach, controlled motion (position and speed) of the axes
is necessary; this requires the provision of actuators, either linear or rotary, associated
power controllers to produce motion, and appropriate sensors to measure the variables.
The overall control of the system is vested in the system computer, which, apart from
sequencing the operation of the overall system, handles the communication between the
operator and the user’s network. It should be noted that industrial robots, which are an
important element of any automated factory, can be considered to be a specific type of
machine tool.
The development of technologies including artificial intelligence and the Internet of
Things has led to the development on the Industry 4.0 concept, which is widely
considered to be the fourth industry revolution, based on the development of smart
factories. Within a smart factory, cyber-physical systems monitor physical processes,
which can then be communicated to allow the decision to be made on a decentralized
basis. This approach to manufacturing is further discussed in Chapter 11, together with
the cyber security issued raised with this approach.