1、 21 English in Mechanical and Electrical Engineering 29 ( ) (CIP) / . 2006.4 (21 ) ISBN 978-7-301-10596-2 . . . . H31 CIP (2006) 024104 ISBN 978-7-301-10596-2/H 1658 205 100871 http:/ http:/ 62752015 62750672 62750667 62754962 pup_ 787 1092 16 15.5 355 2006 4 1 2007 2 2 24.00 010 62752024 fdpup. pku
2、. edu. cn PART ONE Lesson 1 Machine Parts (I) 1 Lesson 2 Machine Parts (II) . 6 Lesson 3 Introduction to Machinery Design 11 Lesson 4 Mechanisms 16 Lesson 5 Basic Concepts in Mechanics . 20 Lesson 6 Engineering Tolerance 25 Lesson 7 Fluid and Hydraulic system 31 Lesson 8 Heat Treatment of Metal. 36
3、Lesson 9 Material Forming Processes(I)41 Lesson 10 Introduction to CAD/CAM . 47 Lesson 11 Fundamentals of Material Forming. 52 Lesson 12 Introduction to Mould. 56 Lesson 13 Introduction of Automobile Engine 62 Lesson 14 Numerical Control 67 Lesson 15 The Automobile Components . 72 PART TWO Lesson 16
4、 Product Test and Quality Control . 78 Lesson 17 Industrial Robots. 83 Lesson 18 Dialogue At CIMT. 88 Lesson 19 A Discussion on Modern Design Optimization 93 Lesson 20 Mechatronics. 99 Lesson 21 CAD/CAM/CAPP. 104 Lesson 22 Material Forming Processes(II)109 Lesson 23 Mould Design and Manufacturing 11
5、5 Lesson 24 Safety and Maintenance for CNC Machine 120 Lesson 25 Car safety 126 Lesson 26 Engine Parts and Operation. 132 VI VI Lesson 27 Using Dynamic Simulation in the Development of Construction Machinery 136 Lesson 28 Virtual Manufacturing 144 Lesson 29 How to Write a Scientific Paper . 148 A .
6、154 B . 155 C . 170 . 237 PART ONE I 1.1 Text Gears 1 Gears are direct contact bodies operating in pairs that transmit motion and force from one rotating shaft to another, or from a shaft to a slide (rack) by means of successively engaging projections called teeth Tooth profiles. The contacting surf
7、aces of gear teeth must be aligned in such a way that the drive is positive i.e., the load transmitted must not depend on frictional contact As shown in the treatment of direct contact bodies this requires that the common normal to the surfaces not to pass through the pivotal axis of either the driv
8、er or the follower. As it is known as direct contact bodies cycloidal and involute profiles provide both a positive drive and a uniform velocity ratio i e conjugate action Basic relations The smaller of a gear pair is called the pinion and the larger is the gear. When the pinion is on the driving sh
9、aft the pair acts as a speed reducer When the gear drives the pair is a speed increaser Gears are more frequently used to reduce speed than to increase it If a gear having N teeth rotates at n revolutions per minute the product N*n has the dimension “teeth per minute”. This product must be the same
10、for both members of a mating pair if each tooth acquires a partner from the mating gear as it passes through the region of tooth engagement For conjugate gears of all types the gear ratio and the speed ratio are both given by the ratio of the number of teeth on the gear to the number of teeth on the
11、 pinion If a gear has 100 teeth and a mating pinion has 20 the ratio is l00/20=5 -Thus the pinion rotates five times as fast as the gear regardless of the speed of the gear Their point of tangency is called the pitch point and since it lies on the line of centers it is the only point at which the to
12、oth profiles have pure rolling contact Gears on nonparallel non-intersecting shafts also have pitch circles but the rolling-pitch-circle concept is not valid Gear types are determined largely by the disposition of the shafts in addition certain types are better suited than others for large speed cha
13、nges This means that if a specific disposition of the shafts is required the type of gear will more or less be fixed On the other hand if a required 2 2 speed change demands a certain type the shaft positions will also be fixed Spur gears and helical gears A gear having tooth elements that are strai
14、ght and parallel to its axis is known as a spur gear A spur pair can be used to connect parallel shafts only 2 If an involute spur pinion were made of rubber and twisted uniformly so that the ends rotated about the axis relative to one another the elements of the teeth initially straight and paralle
15、l to the axis would become helices The pinion then in effect would become a helical gear Worm and bevel gears In order to achieve line contact and improve the load carrying capacity of the crossed axis helical gears the gear can be made to curve partially around the pinion in somewhat the same way t
16、hat a nut envelops a screw The result would be a cylindrical worm and gear Worms are also made in the shape of an hourglass, instead of cylindrical so that they partially envelop the gear This results in a further increase in load-carrying capacity Worm gears provide the simplest means of obtaining
17、large ratios in a single pair They are usually less efficient than parallel-shaft gears however because of an additional sliding movement along the teeth V-belt The rayon and rubber V-belt are widely used for power transmission Such belts are made in two series the standard V-belt and the high capac
18、ity V-belt The belts can be used with short center distances and are made endless so that difficulty with splicing devices is avoided First cost is low and power output may be increased by operating several belts side by side All belts in the drive should stretch at the same rate in order to keep th
19、e load equally divided among them. When one of the belts breaks, the group must usually be replaced. The drive may be inclined at any angle with tight side either top or bottom. Since belts can operate on relatively small pulleys, large reductions of speed in a single drive are possible. Second the
20、included angle for the belt groove is usually from 34 to 38 .The wedging action of the belt in the groove gives a large increase in the tractive force developed by the belt. Third pulley may be made of cast iron, sheet steel, or die-cast metal. 3 Sufficient clearance must be provided at the bottom o
21、f the groove to prevent the belt from bottoming as it becomes narrower from wear. Sometimes the larger pulley is not grooved when it is possible to develop the required tractive force by running on the inner surface of the belt. The cost of cutting the grooves is thereby eliminated. Pulleys are on t
22、he market that permit an adjustment in the width of the groove. The effective pitch diameter of the pulley is thus varied, and moderate changes in the speed ratio can be secured. Chain Drives The first chain-driven or “safety” bicycle appeared in 1874, and chains were used for driving the rear wheel
23、s on early automobiles. 4 Today, as the result of modern design and production methods, chain drives that are much superior to their prototypes are available, and these have contributed greatly to the development of efficient agricultural machinery, well-drilling equipment, and mining and construction machinery. Since about 1930 chain drives
