Thermodynamic efficiency of an actuator that provides the mechanical movement for the driven equipments:

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1 1. Introduction 1.1. Industry Automation Industry automation is the term that describes a vital development programme of a production community where the project engineers build up automated manufacturing applications using equipment designed for the structured processing of product materials, energy and information. In the automated manufacturing application the transformation and transmission of the materials, energy and information take place without direct human interference in hierarchical series of processes, tasks, works, activities and operations. The role of a worker is to start the processes of automated manufacturing application and supervise the system. The system will do the rest. Understanding an existing or composing a new description about an automated manufacturing system presupposes that some important realization terms used in industry automation are organized into intelligent (meaningful) hierarchy, e.g. life, programme, project, game, application, process, task, work (program) activity, and operation Nature of actuators I. An actuator is capable of doing physical work. The actuator is a controllable mechanical device for performing manufacturing operations. An actuator uses electrical, hydraulic or pneumatic energy from den external source, converts and transmits it into mechanical movement energy (physical work) of a manufacturing device due which the form and nature of the product material and manufacturing device may alter. II. An actuator is a controllable mechanical device for performing manufacturing operations. It converts and transmits the applications of electrical, hydraulic or pneumatic energy in order to achieve the mechanical movement energy (physical work) needed for making products. Thermodynamic efficiency of an actuator that provides the mechanical movement for the driven equipments: useful _ energy output _ energy ε = = used _ energy input _ energy 1.2. Classification of actuators used in product automation. Actuators are classified by the type of energy transmitted from an energy source: (Fig. 1.1) Electrical, Pneumatic, Hydraulic, Mechanical.

2 Fig. 1.1 Classification of actuators by the type of energy transmitted from an energy source Actuators are classified by the type of energy flowing into the resource (object): (Fig. 1.2) electrical pneumatic hydraulic mechanical Fig Classification of actuators by the type of energy flowing into the resource Actuators are classified by the type of input energy and by the internal conversion outcome the output energy that is transmitted to the driven equipment (Fig. 1.3): electrical to mechanical electrical to pneumatic electrical to hydraulic pneumatic to mechanical piezo to electrical etc.

3 Fig. 1.3 Classification of actuators by the type of input energy and by the internal conversion outcome the output energy that is transmitted to the driven equipment Actuators are also classified by the form of mechanical movement (shape of geometrical movement) that is applied from the output of the actuator towards the input of driven equipment (Fig. 1.4): rotary actuators linear actuators trajectional actuators with trajectory generators Fig. 1.4 Classification of actuators by the form of mechanical movement Very different actuators are used in order to achieve the mechanical movement necessary for the driven equipment: (Fig. 1.5) electrical drives pneumatic cylinders hydraulic cylinders kinematic rods Fig. 1.5 Classification of actuators by the mechanical movement necessary for the driven equipment Electro-mechanical actuators are similar to their mechanical equivalents. In such case the mechanical control lever has been replaced with electric motor. Electric motors combined with kinematic pairs can be used to achieve linear motion. Rotary motion of an electric motor

4 is converted to linear at the output of the actuator, for example by using a ball screw pair and guide rails. The selection of an actuator type depends on the technical requirements for the design of an application. Electrical drive is also an actuator. There are more complex actuators such as electrical drives with frequency converters, servo drives and drives with stepper motors. The developers are using information, energy and physical manufacturing technology together with modern development methods in order to produce automated manufacturing system. People, automatic control systems and driven energetic (mechanical) equipment are integrated during the system development. New manufacturing equipment enables us to produce more complicated products. The technology used in manufacturing products is becoming more complex. In the information age the production workers involved in making products regularly participate in further training. The general structure chart of automated manufacturing systems (applications) is given in (Fig. 1.6). Automated manufacturing system (application) Worker Automatic controller for product manufacturing Task A Control program Task B Task C Energy source G E - energy to converter input Control system of the machine Reference node The machine automatic controller. Production control program Actuator (drive) Regulator Actuator control values Feedback values from the actuator Power, speed and position converter Drive motor Machine (mechanical work) Produced product Tool Worktable Position sensor Reference values for work: position change in time, power, torque etc Feedback values from the working machine Mechanical energy, load torque, actuator moving speed, position, direction

5 1.3. Selection of actuator mechanisms The task of choosing the right kind of actuator mechanisms is complicated and highly responsible because actuators influence the whole automated manufacturing system dynamically. The actuator type determines the power supply (e.g. direct or alternating current) and the transmission mechanism for the system. Sometimes it is possible to achieve the desired movement by integrating the actuator directly to the system and the use of transmission mechanism can be avoided. For example, linear movement can be achieved without the use of rotary motor by using the linear motor instead. When choosing an actuator, a designer has to think about the following parameters: continuous power output maximal force / torque that an actuator can continuously output without overheating range of motion the range of linear or circular movement resolution the smallest step of the developed force / torque accuracy the uninflected ratio between input and output peak force / torque the highest force / torque achievable for an actuator heat dissipation the maximum heat dissipation power in steady running conditions speed characteristics characteristic of the force / torque and speed idle speed speed in a state where no load is applied frequency response frequency range where the output still responds to the input properly power supply energy supply type (electric current, compressed air etc) Additionally, another determining task is the selection of the transmission mechanism. For example if gear transmission is chosen, the accuracy could be compromised due to the development of a slack. The same applies to belt drives if the belt should begin to slip Self check 1. What do we mean by industry automation? 1. Industry automation is energy and information processing. 2. Industry automation is control of a production process. 3. Industry automation is simplification of a production process. 4. A vital development programme of production community where the project engineers build up automated manufacturing applications. 2. What is an actuator? 1. An actuator is a device for converting and transmitting energy. 2. An actuator is a controllable mechanical device for performing manufacturing operations. 3. An actuator hydraulic or pneumatic converter. 4. Actuator is an electronic device. 3. How are the actuators categorized?

6 1. By the type of energy transmitted from an energy source. 2. By the form of mechanical movement. 3. By the shape and size of geometrical movement. 4. What parameters should be taken into account when choosing an actuator? 1. Range of motion and maximal force 2. Heat dissipation power. 3. Frequency response regency. 4. Start-up count. 5. Colour of a shaft.