Automatics

Automatics

Automatics - The most general methods of achieving partial or complete automatic working are given below:

(a) Adaptations of orthodox machines by adding suitable feeding arrangements. Examples of this are the fitting of feed hoppers (e.g. to a centreless grinder) and continuous means of feeding material (e.g. strip feed rolls on a power press).

(b) Machines on which settings may be made for anyone of a variety of components within the capacity of the machine. Machines under this heading are widely used for turning and are known under the general term of automatics. The feeding and turning movements are actuated and controlled by cams and mechanical movements, and these may be designed or set to suit any given set of conditions as imposed by a particular component.

A semi automatic is a turning machine adapted for chuck work (rather like an automatic turret lathe) where, although the movements are automatically controlled, the work has to be hand loaded into and removed from the chuck at the beginning and end of each cycle of operations. The semiautomatic principle is also applied to internal grinding and other forms of machining.

(c) Machines designed specifically for operations on a particular component. Machines of this kind have been commonly used for drilling and profiling operations. Of recent years the construction of machines of this character has been speeded up and cheapened by the employment of standard units which may be assembled together to suit any required set of conditions.

(d) Machines made up of a collection of machining units assembled and used in conjunction with some form of conveyor or indexing work table so that the work may be automatically moved through the sequence of operations concerned.

This form of working has become known as transfer machining and was first developed in early 1920's for the machining of motor car cylinder blocks, gearbox casings and similar components in the form of a casting upon which a series of milling, drilling and boring operations were necessary.

Transfer machines are often very costly, occupy considerable space, and may take a long time to build. They are thus essentially associated with long production runs on the same component, although in some forms they possess flexibility for being changed over from one component to another.

During recent years the automation of machining has been carried a stage further by the introduction and development of various systems of electrical control and, in particular, by the employment of electronic computers. These methods represent a radical departure from all previous ideas of automatic working, where the actuation and control were vested in mechanical movements.

One important characteristic which can be associated with electronic control is that known as feedback. Under this principle, information from the element being controlled (e.g. the tool or cutter) is fed back electrically into the controlling system, and in this way a continuous system of monitoring and correction goes on.

With mechanical control under normal systems for (say) machining, the dimension of the machined surface depends of some train of mechanical connections and any variation which may occur in this train will result in a variation which will come to light only as a result of a subsequent check on the machined surface.

The operation of feedback in electrical control is somewhat analogous to what would occur in a mechanical system if a continuous measuring element in the machining zone could be made to signal back to the cam and/or mechanism and, in so doing, could cause automatic correction to be made for any wear or other variations taking place.