Alexus CameroMAE 3192HW #717 November 2015

Chapter 37

2. a. Explain the difference between hard and soft automation.Automation is defined as the process of enabling machines to follow a prearranged series of operations

with little or no human intervention, and using specialized equipment/devices that perform and control manufacturing processes and operations. The machines in hard automation, or fixed-position automation, are designed to produce a standard product, like a gear or shaft. Since these machines are specialized, they lack flexibility. Also, the economical use of these machines requires mass production since they are expensive to design and build. The machines are usually called transfer machines that consist a power-head production units and transfer mechanisms. They are usually built on the modular (building-block) principle. Soft automation, however, has a greater flexibility through the use of computer control of the machine and of its functions. Soft automation can produce parts with complex shapes. The machines in soft automation can be programmed easily and readily to produce a part with different shapes or dimensions from the part prior to it. b. Why are they so called?

Fixed-position (hard) automation refers to the use of specialized machines to automate a fixed sequence of operations. Flexible/programmable (soft) automation refers to the use of machines that are easily programmable to produce sets of parts with different shapes and dimensions.

3. Describe the principle of numerical control of machines. Explain what is numerical control of a machine.Numerical control, abbreviated NC, is a method of controlling the movements of components of a

machine by directly inserting coded instructions in the form of numbers and letters into the system. The system then interprets the data from the inserted coded instructions and converts them to output signals, which then control different machine components. Desired series of steps by the machines can be carried out by the coded instructions made by a programmer. Numerical-control machines are then capable of producing parts repeatedly and accurately and of handling different parts simply by loading different part programs or codes.

4. Explain open-loop and closed-loop control circuits.In an open-loop control circuit in an NC machine, controller or computer sends signals or information to

the servomotor or machine to tell it where to move the worktable or what to do next. But the movements and final positions of the worktable are not checked for accuracy since there is no way of getting information back to the computer. In the closed-loop control circuit, it is equipped with various transducers, sensors, and counters that accurately measure the position of the worktable and then send signals back to the computer so the computer can perform necessary adjustments.

7. a. Describe the features (basic components) of an industrial robot.An industrial robot has a number of basic components. A manipulator, also called an arm and wrist, is a

mechanical unit that provides motions or trajectories. The end of the wrist can reach a point in space having a specific set of coordinates and in a specific orientation. An end effector (from the end of the wrist), also called end-of-arm tooling, may be equipped with devices such as grippers, hooks, spray guns for painting, power tools, or measuring instruments. An end effector commonly uses mechanical grippers that are equipped with two or more fingers. A power supply (from an electrical, a pneumatic, or hydraulic power supply) of an industrial robot controls and regulates each motion of the manipulator. The controller, or control system, is the communications and information-processing system that gives commands for the movements of the robot. It stores data to initiate and terminate movements of the manipulator. It also interfaces with computers and other equipment.