Monitoring, Active

Monitoring, Active 

the checking of parts outside a machine tool or during processing of a tool; it provides information on the necessity of changing the operating conditions or adjusting the machine (changing the position of the tool relative to the workpiece). This type of monitoring is called active because of the degree to which it constitutes a part of the technological process of machining. It is mainly used in finishing parts on grinders and honing lathes. Active monitoring for adjustment— in which measurement data based on the results of measurements of finished parts or batches of parts outside the machine are used for automatic adjustment or stopping of the machine— is a special type of monitoring. Equipment for adjustment monitoring sometimes performs the functions of an automatic monitoring machine.

Active monitoring may be carried out by indirect measurements, where the quantity being checked is the position of a machine’s elements (such as a grinding wheel or carriage) that determine the size of a part, or, more often, by direct measurement of the part.

Active monitoring may be manual; an operator controls the operating conditions and stops the machine according to the readings of an instrument that measures the part during machining. It may also be automatic, when the machine is controlled by an instruction issued by a device that is mounted on or outside the machine or is part of it.

The instruments used for active monitoring are classified as command types, whose signals are fed into the automatic control system of a machine, and indicating (reading), signal, or signal-indicating types, which enable the operator to use their data for manual control of the machine. Command instruments may have reading or signaling devices.

According to the method of mounting the measuring units on the machine, instruments for active monitoring are divided into devices with an attached gauge, which are usually placed on the part and removed from it by the operator, and bench-mounted devices, which are automatically placed on the part and removed from it. According to method of operation, instruments for active monitoring may be mechanical (for example, with a dial gauge), pneumatic, inductive, or capacitive. Pneumatic instruments are the most common in the USSR. Active-monitoring instruments are set according to master parts.

A special group is represented by active-monitoring instruments for coupled grinding, which make possible measurement of a shaft during machining and stopping of the machine when the shaft reaches a size that will ensure the required clearance or tightness with a previously machined hole (for example, machining a spindle for the hole in the headstock of a lathe). Active monitoring is used mainly in mass and large-series production, but its use is sometimes expedient in the manufacture of small batches of parts (as few as ten).

Active monitoring makes possible an increase in labor productivity, improvement of machining quality, simultaneous operation of several machines, production of highly precise parts, and use for such operations of relatively low-skilled workers.

A promising area is the development of active-monitoring instruments that operate without being set according to master parts and have automatic resetting of the adjustment level (devices that establish optimum conditions for the production process), as well as the extension of the application of such instruments to all forms of machine tools.

REFERENCES

Kondashevskii, V. V. Avtomaticheskii kontroV razmerov detalei v protsesse obrabotki. Moscow, 1951.
Volosov, S. S. Osnova tochnosti aktivnogo kontrolia razmerov, 2nd ed. Moscow, 1969.
Aktivnyi kontroV v mashinostroenii. Edited by E. I. Ped’. Moscow, 1971.

N. M. MARKOV