Servo Motors free essay sample

Servo motor This is a small motor in a C-band dish feed assembly. This motor selects whether vertical or horizontal polarization is to be received. Servo motor A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. As the coded signal changes, the angular position of the shaft changes. Three basic types of servo motors are used in modern servosystems: ac servo motors, based n induction motor designs; dc servo motors, based on dc motor designs; and ac brushless servo motors, based on synchronous motor designs. Figure 9 Typical dc servo motor system with either encoder or resolver feedback. Some older servo motor systems use a tachometer and encoder for feedback. Servomotor Applications 45 ratings | 3. We will write a custom essay sample on Servo Motors or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page 49 out of 5 [pic]Print Table of Contents 1 . Press Feed 2. In-line Bottle Filling 3. Precision Auger Filling System 4. Label Applications 5. Random Timing Infeed System 6. Buy the Book Press Feed You will get a better idea of how servomotors and amplifiers operate if you see some ypical applications. Figure 11-90 shows an example of a servomotor used to control a press feed. In this application, sheet material is fed into a press where it is cut off to length with a knife blade or sheer. The sheet material may have a logo or other advertisement that must line up registration marks with the cut-off point. In this application the speed and position of the sheet material must be synchronized with the correct cut-off point. The ball-screw mechanism is also called a lead screw. When the motor turns the shaft of the ball crew, the carriage will move horizontally along the length of the ball-screw shaft. This movement will be smooth so that each of the nozzles can dispense product into the bottles with little spillage. The servo drive system utilizes a positioning drive controller with software that allows the position and velocity to be tracked as the conveyor line moves the bottles. A master encoder tracks the bottles as they move along the conveyor line. An auger feed system is also used Just prior to the point where the bottles enter the filling station. The auger causes a specific amount of space to be set between each bottle as t enters the filling station. The bottles may be packed tightly as they approach the auger, but as they pass through the auger their space is set exactly so that the necks of the bottles will match the spacing of the filling nozzles. A detector is also in conjunction with the dispensing system to ensure that no product is dispensed from a nozzle if a bottle is missing or large spaces appear between bottles. FIGURE 11-91 Application of a beverage-filling station controlled by a servomotor. (Courtesy 01 Electro-craft, A Rockwell Automation Business. ) The servo drive system compares the position of the bottles from the master encoder o the feedback signal that indicates the position of the filling carriage that is mounted to the ball screw. The servo drive amplifier will increase or decrease the speed of the ball-screw mechanism so that the nozzles will match the speed of the bottles exactly. Precision Auger Filling System A third application for a servo system is provided in Fig. 11-92. In this application a large tilling tank is used to till containers as they pass along a conveyor line. T material that is dispensed into the containers can be a single material fill or it can be one of several materials added to a container that is dumped into a mixer for a lending operation. Since the amount of material that is dispensed into the container must be accurately weighed and metered into the box, an auger that is controlled by a servo system is used. The feedback sensor for this system can be a weighing system such as the load cell discussed in earlier chapters. The command signal can come from a programmable controller or the operator can enter it manually by selecting a recipe from the operators terminal. The amount of material can be different from recipe to recipe. FIGURE 11-92 Application of a precision auger filling station controlled by a servomotor. Courtesy of Electro-craft, A Rockwell Automation Business. ) The speed of the auger can be adjusted so that it runs at high speed when the container is first being filled, and the speed can be slowed to a point where the final grams of material can be metered precisely as the container is filled to the proper point. As the price of material increases, precision filling equipment can provide savings as well as quality in the amount of product used in the recipe. Label Applications The fourth application has a servomotor controlling the speed of a label-feed mechanism that pulls preprinted labels from a roll and applies them to packages as hey move on a continuous conveyor system past the labeling mechanism. The feedback signals are provided by an encoder that indicates the location of the conveyor, tach generator that indicates the speed of the conveyor, and a sensor that indicates the registration mark on each label.