机电一体化专业英语Unit 9.ppt

1、Introduction to Motors,Part I Technical and Practical Reading,Passage A The Motor Basics (I),The function of the motor is to convert electrical energy to mechanical energy. Thus, the motor is also classified as an electromechanical device/machine. Basics of Electromagnetic Forces Electromagnetic For

2、ce The direction of magnetic flux produced by a permanent magnet is always from N-pole to S-pole. When a conductor is placed in a magnetic field and current flows in the conductor, the magnetic field and the current interact each other to produce force. The force is called Electromagnetic force (Fig

3、. 9-1).,The flemings left hand rule determines the direction of the current, the magnetic force and the flux. Stretch the thumb, the index finger and the middle finger of your left hand as shown in Fig. 9-2. When the middle finger is the current and the index finger the magnetic flux, the direction

4、of the force is given by the thumb.,Magnet field produced by current The magnetic fields produced by the current and the permanent magnets works to produce electromagnetic force. When the current flows in the conductor toward the reader, the magnetic field in the CCW direction will be produced aroun

5、d the current flow by the right-handed screw rule (Fig. 9-3).,Interference of a line of magnetic force The magnetic fields produced by the current and the permanent magnets interfere each other (Fig. 9-4). The line of magnetic force distributed in the same direction acts to increase its strength, wh

6、ile the flux distributed in the opposite direction acts to reduce its strength.,Electromagnetic force production The line of magnetic force has a nature to return to the straight line by its tension like an elastic band. Thus, the conductor is forced to move from where the magnetic force is stronger

7、 to where it is weaker (Fig. 9-5).,Torque production Electromagnetic force is obtained from the equation; Fig. 9-6 illustrates the torque obtained when a single-turn conductor is placed in the magnetic filed. The torque produced by the single conductor is obtained from the equation; T(torque) F (for

8、ce) R (distance from the center to conductor) Here, there are two conductors present;,Principles of Motor Motion 1. Place Permanent Magnet Place permanent magnets so that different polarities face each other. Thus, a parallel magnetic field will be created (Fig. 9-7). 2. Place Armature Place the arm

9、ature in the parallel magnetic field and conduct magnetization to have N-polarity at and S-polarity at and . Then, the armature will start CW rotation due to magnetic attraction and repulsion (Fig. 9-8).,3. Magnetize Armature Wind the coil and flow the current so that the armature will be magnetized

10、 (Fig. 9-9). 4. To Keep Rotation To keep the armature running, the current direction should be changed so that the N-polarity stays at upper portion and S- polarity stays at under portion of the armature (Fig. 9-10).,5. Switch Current Direction To change the current direction, coil shall be connecte

11、d to the metal strips (commutator) shaped as a cylinder divided into three (Fig. 9-11). 6. Place Brush To keep CW rotation, apply plus (+) voltage to the left and minus () to the right brush. If CCW rotation is required, apply minus () voltage to the left and plus (+)to the right brush, or reverse t

12、he polarity of the magnet (Fig. 9-12).,Notes,1、Place the armature in the parallel magnetic field and conduct magnetization to have N-polarity at and S-polarity at and . 全句为祈使句；Place和conduct为并列结构。全句译为：在磁场的平行方向置入电枢，同时产生了磁化现象，处是N极、和处是S极。 2、To keep the armature running, the current direction should be c

13、hanged so that the N-polarity stays at upper portion and S- polarity stays at under portion of the armature.本句是结果状语从句。To keep the armature running置于居首为强调。本句译为：为了保持电枢旋转，应改变电流方向，这样N极总在电枢的上部，S极总在电枢的下部。,1、The direction of magnetic flux is usually considered from S-pole to N-pole. 2、The magnetic fields p

14、roduced by the current and the magnetic flux works to produce permanent magnets. 3、The line of magnetic force has a property to return to the oblique line by its tension. 4、As you known, the torque is obtained when a single-turn conductor is put in the magnetic filed. 5、If CCW rotation is required,

15、use minus (+) voltage to the left and plus () to the right brush.,EXERCISE 1,Mark the following statements with T (True) or F (False) according to the passage.,(F),(F),(F),(T),(F),magnetic flux _ _ 电磁力 3. permanent magnet _ _ 右手螺旋定则 5. magnetic field _ _ 磁力线 7. elastic band _ _ 直线,EXERCISE 2 Transla

16、te the following phrases into Chinese or English.,磁通,electromagnetic force,永久磁铁,right-handed screw rule,磁场,line of magnetic force,松紧带,straight line,Passage B Sheet Metal Forming,Function of Main Motor Parts 1. Produce Magnet Field Black-colored portions are permanent magnets that maintain magnetic f

17、orce, and are fixed to a motor-housing. The motor-housing itself produces a magnetic circuit (a magnetic field) with a core (a green-colored portion) and the permanent magnets as a path for the magnetic force to flow (Fig. 9-13). 2. Provide Current Current enters the motor from one of the terminals

18、(a portion sticks out forward). It flows to a winding (an orange-colored portion) via brushes (a brown-colored portion) and a commutator, and goes out of the motor from the other terminal via the brushes and the commutator (Fig. 9-14).,3. Output by Rotation The current flows into the magnet field pr

19、oduced by the permanent magnets, and that produces electromagnetic force. The commutator switches the direction of the current in exact timing to have continuous rotation. The output is pulled out through a shaft (Fig. 9-15).,Explanation of Motor Parts,List of terms on motor performance,General Inst

20、ructions for Use of Motors In handling motors, be sure to read these general instructions to ensure safe, secure, and correct use of the motors. Warning 1. Do not insert a lead or motor terminal into a home outlet. You might get an electric shock from this. 2. When applying current, do not touch a l

21、ive part such as a current-carrying terminal. You might get an electric shock from this. 3. When applying current, keep your hand or finger off a rotary part. Otherwise, you might get hurt. 4. DONT leave motor shaft locked while power is applied, as even a short-time lock-up may cause excess heat bu

22、ild up resulting in burning damage to the motor depending on its specifications. 5. Depending on motor operating state (mounted state, load, and environmental temperature), the motor might generate excessive heat. Be careful not to burn yourself due to the heat.,EXERCISE 3,Choose the best operation

23、orders according to the information given.,Stator B. Rotor C. Spring D. Permanent Magnets E. Windings,B,E,D,A,C,S.P. Standard Pressure _ 2. SR Slant Range _ 3. SS Stainless Steel _ 4. ss Spindle Speed _ 5. S.S.C. Semi-steel Casting _ 6. ST Standard Temperature _ 7. st. c. Steel Casting _ 8. str. st.

24、 Structure Steel _,EXERCISE 4 Abbreviations are very useful in practical work. Read them and then translate them into corresponding Chinese terms.,标准压,斜距,不锈钢,主轴转速,半钢铸件,标准温度,钢铸件,结构钢,Part II Glance at Conventional Machine Tool Structures,The following is the Vice Jaw Structures。,Motor Control Overview

25、,Explanations of the Motor Control Terms,EXERCISE 5 The following is the Vice Jaw. After reading them, you are required to choose the suitable words or phrases given below.,Power supply Terminal box Bearing Rotor Drive pulley Centrifugal switch Cooling fan Stator,Part III Simulated Writing Section A

26、 Match Your Skill The following is the Lathe Accessories, and you can understand the name of Inner Dial Caliper Gauge.,Explanations of the Motor Terms,EXERCISE 6 Complete the information by translating the part given in Chinese.,Leeson Reversible Electric Motor 5 HP, 1740 RPM, Model# 131537 This Lee

27、son heavy-duty single phase, open drip-proof motor turns at 1740 RPM and is electrically reversible.,Section B Have a Try This section will help you to understand several forms of machining, and you can see the simple way a small part is produced.,Internal Operations Taping - An operation in which a

28、 tap enters the workpiece axially and cuts internal threads into an existing hole. The existing hole is typically drilled by the required tap drill size that will accommodate the desired tap. On a milling machine, the threads may be cut to a specified depth inside the hole (bottom tap) or the comple

29、te depth of a through hole (through tap).,EXERCISE 7 This section is to test your ability to Identifying following features of different operations.,Tapping (Milling machine),Tapped hole,Bored chamfer,Part IV Broaden Your Horizon - Practical Activity,Mini Motor Repair STEP 1: If you look at the end

30、cap of the motor housing, you will see (4) metal corners bent at an angle to hold the end cap on. All you have to do is take your pliers and bend them in the opposite direction so that you can remove the end cap. Then use a flathead screwdriver to pry the end cap off (see Figure 1 4).,STEP 2: Pull t

31、he center shaft out from the motor case (see Figure 5).,STEP 3: With the end cap removed and separated from the shaft, use your Digital Ohm Meter to test both outside terminals to see if there is any resistance. If you find that there is Zero resistance at the terminals, then that would indicate tha

32、t your circuit is closed when it should be open, this means your capacitor has a short in it. Locate the capacitor on the end cap. Use a pair of wire cutters to separate the connection, as shown in the photos. Be sure to position it so that it doesnt reconnect on accident. Use your Ohm Meter to retest both outside terminals again, and you should see that the circuit is now open, and indicates full resistance. This will confirm that you have corre