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Hydraulics

Hyraulic motors are mainly used for heavy-duty machines that require high torque or force. Control of hyraulic motor is, however, more difficult due to nonlinear characteristics of various components in the hyddraulic system. These actuators are used to construct feed drives and, therefore, are required to have good velocitycontrollability. Asignal from the controller is amplified and supplied to the motor. The motor produces a torque to rotate the shaft through a coupler, while linear motors drive the table directly. The position or velocity signal measured by an encoder, a resolver, or a

tachometer is fed back to the controller so that closed-loop control of the feed drive can be achieved.

(Dorf, R.D., Kusiak, A., Handbook of Design, Manufacturing and Automation,1994, pg.247)

Cladding

Explosive welding or cladding, as it is often called, brings together two metal surfaces with sufficient impact and pressure to bond. Pressure is developed by a high-explosive shot placed in contact with or in close proximity to the metals. In some instances a protective material such as rubber is placed over the upper panel to prevent damage to the surface. The entire assembly is placed upon a buffer plate or anvil to absorb energy generated during yje jıining operation. Of the two arrangements showing cladding or laminating of metals, the left one is preferred.

To obtain a metallurgical bond, atoms from boh surfaces must come into intimate contact. The oxides and films always present on the surface of metals are broken or dispersed by high

pressure or dissolved in the molten region. The explosive force brings the clean surfaces together and produces a sound bond.

(Amstead, B. H., Ostwald,P. F., Begeman, M. L., MAnufacturing Processes,8th Edition, pg. 189)

Cupola

Heat is provided externally ( for example, by electric, gas , or oilheating), internally(as by electic induction) or, only for cast iron, by mixing the fuel with the charge itself. CAst iron is usually melted semicontinuously in a vertical shaft furnace (cupola); lining of the cupola with a refractory is being abondened in favor of water-cooled steel jackets. The charge is mixe

d with coke and some minerals(primarily limestone, CaCO3), and hot air is blown through the column. Coke burns to give heat and is also a source of carbon for the cast iron. The liquid metal is tapped at the bottom, seperately from the slag which is formed by the limestone with nonmetallic contaminants and metal oxides. In the duplex process, the liquid metal is tapped into an electic holding furnace where alloying and suğerheating is also practiced.

(Schey, J., A., Introduction to Manufacturing Processes, 2nd Edition, pg.148-149)

Feedforward Control

The strategy in feedforward control is to anticipate the effect of disturbances that will upset the process by sensing them and compansating for them before they can affect the process. As shown in Figure, the feedforward control elements sense the presence of a disturbance and take corrective action by adjusting a process parameter that compensates for any effect the

disturbance will have on the process. In the ideal case, the compensation is completely effective. however, complete compensation is unlikelybecause of imperfections in the feedback measurements, actuator operations, and control algorithns, so feedforward control is usually combined with feedback control, as shown in our figure. Regulatory and feedforward control are more closely associated eith the process industries than with discrete production manufacturing.

(Groover, M. P., Automation, Production Systems and Computer-Integrated Manufacturing, 3rd Edition, pg.93)