DANANG UNIVERSITY UNIVERSITY OF SCIENCE AND TECHNOLOGY FALCUTY OF MECHANICAL ENGINEERING Danang, 2017 TABLE OF CONTENTS TABLE OF CONTENTS i ELECTRONIC SYSTEMS CHAPTER 1: INTRODUCTION LOGIC GATES CHAPTER 2: LOGIC GATES INTEGRATED CIRCUIT APPLICATIONS CHAPTER 3: BASIC ELECTRONIC COMPONENTS 10 RESISTANCE 10 CAPACITOR 12 DIODE 13 LIGHT EMITTING DIODE 16 BIPOLAR JUNCTION TRANSISTOR (BJT) 20 CHAPTER 4: MICROCONTROLLER .22 INTRODUCTION 22 IMPORTANT FEATURES 24 WHY PIC? 31 MECHANICAL SYSTEMS 33 English for Mechatronics Engineering i CHAPTER 1: INTRODUCTION 33 MECHANISMS 33 TYPES OF MOTION 35 DEGREE OF FREEDOM 35 CHAPTER 2: CAMS 37 ECCENTRIC CAM 38 DROP CAM 39 FLAT CAM 41 CHAPTER 3: GEARS 43 SPUR GEAR 44 HELICAL GEAR 45 DOUBLE HELICAL GEAR 46 BEVEL GEAR 47 WORM GEAR 48 RACK AND PINION 50 GEAR TRAIN 51 CHAPTER 4: BELT AND CHAIN DRIVES .54 PROS AND CONS 55 FLAT BELTS 55 ROUND BELTS 57 VEE BELTS 57 TIMING BELTS 59 CHAIN DRIVE 60 English for Mechatronics Engineering ii CHAINS VERSUS BELTS 61 CHAPTER 5: BEARINGS .63 DEEP-GROOVE 64 FILLING - SLOT 65 ANGULAR CONTACT 65 DOUBLE-ROW 67 SELF-ALIGNING 68 STRAIGHT-ROLLER BEARING 69 TAPER ROLLER 70 NEEDLE ROLLER 72 English for Mechatronics Engineering iii ELECTRONIC SYSTEMS CHAPTER 1: INTRODUCTION Many control systems are concerned with setting events in motion or stopping them when certain conditions are met For example, with domestic washing machine, the heater is only switched on when there is water in the drum and it is to the prescribed level Such control involves digital signals where there are only two possible signal levels Digital circuitry is the basis of digital computers and microprocessor controlled systems There are two input signals which are either or signals and an output signal which is or signal The controller is here programmed to only give a output if both the input signals are Such an operation is said to be controlled by a logic gate Logic gate is the basic building blocks for digital electronic circuits The term combinational logic is used for the combining of two or more basic logic gates to form a required function English for Mechatronics Engineering LOGIC GATES Logic gates are the basic components in digital electronics They are used to create digital circuits and even complex integrated circuits For example, complex integrated circuits may bring already a complete circuit ready to be used – microprocessors and microcontrollers are the best example – but inside them they were projected using several logic gates In this tutorial we will teach you everything you need to know about logic gates, with several examples As you may already know, digital electronics accept only two numbers, “0” and “1.” Zero means a V voltage, while “1” means V or 3.3 V on newer integrated circuits You can think “0” and “1” as a light bulb turned off or on or as a switch turned off or on AND gate: Suppose we have a gate giving a high output only when both input A and input B are high; for all other conditions it gives a low output This is an AND logic gate We can visualize the AND gate as an electric circuit involving two switches in series Only when switch A and B are closed, there is a current (a) Represented by switches (b) Symbols The relationship between the inputs and the outputs of an AND gate can be expressed in the form of an equation, called Boolean equation The Boolean equation for the AND gate is written as A.B=Y An example is a burglar alarm in which it gives an output, the alarm sounding, when the alarm is switched on and when a door is opened to active a sensor English for Mechatronics Engineering The relationships between inputs to a logic gate and the outputs can be tabulated in a form known as truth table This specifies the relationships between the inputs and outputs We can write the truth table as A B 0 1 1 Output OR gate: An OR gate with inputs A and B gives an output of a when A or B is We can visualize such a gate as an electric circuit involving two switches in parallel When switch A or B is closed, then there is a current OR gates can also have more than inputs We can write the Boolean equation for an OR gate as: A+B=Y (a) Represented by switches A B 0 1 1 English for Mechatronics Engineering (b) Symbols Output NOT gate: a NOT gate has just one input and one output, giving a output when the input is and a when input is The NOT gate gives an output which is the inversion of the input and is called an inverter The representing NOT actually symbolizes logic identity, i.e no operation, and the inversion is depicted by the circle on the output Thus, if we have a digital input which varies with time, the output variation with time is the inverse The Boolean equation describing the NOT gate is AY A bar over a symbol is used to indicate that the inverse, or complement, is being taken; thus the bar over the A indicates that the output Y is the inverse value of A Input Output NAND gate: The NAND gate can be considered as a combination of an AND gate followed by a NOT gate Thus when input A is and input B is 1, there is an output of 0, all other inputs giving an output of The NAND gate is just the AND gate truth table with the outputs inverted An alternative way of considering the gate is as an AND gate with a NOT gate applied to invert both the inputs before they reach the AND gate The figure below shows the symbols used for the NAND gate, being the AND symbol followed by the circle to indicate inversion English for Mechatronics Engineering The Boolean equation describing the NAND gate is: A B  Y The following is the truth table: A B 0 1 1 Output NOR gate: The NOR gate can be considered as a combination of an OR gate followed by a NOT gate Thus when input A or input B is there is an output of It is just the OR gate with the outputs inverted An alternative way of considering the gate is as an OR gate with a NOT gate applied to invert both the inputs before they reach the OR gate The figure below shows the symbols used for the NOR gate; it is the OR symbol followed by the circle to indicate inversion The Boolean equation for NOR gate is: A B Y The following is the truth table for the NOR gate English for Mechatronics Engineering A B 0 1 1 Output XOR gate: XOR stands for exclusive OR XOR gate compares two values and if they are different its output will be “1.” XOR operation is represented by the symbol ⊕ So Y = A ⊕ B is the Boolean equation for the XOR gate The following is the truth table for the XOR gate A B 0 1 1 Output XNOR gate: XNOR stands for exclusive NOR and is an XOR gate with its output inverted So, its output is at “1” when the inputs have the same value and “0” when they are different XNOR operation is represented by the symbol (·) The Boolean equation for XNOR gate is: A (·) B = Y English for Mechatronics Engineering CHAIN DRIVE Chain drive is a way of transmitting mechanical power from one place to another It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles It is also used in a wide variety of machines besides vehicles Most often, the power is conveyed by a roller chain, known as the drive chain or transmission chain, passing over a sprocket gear, with the teeth of the gear meshing with the holes in the links of the chain The gear is turned, and this pulls the chain putting mechanical force into the system Slip can be prevented by the use of chains which lock into teeth on the rotating cylinders to give the equivalent of a pair of intermeshing gear wheels A chain drive has the same relationship for gear ratio as a simple gear train Chains enable a number of shafts to be driven by a single wheel and so give a multiple drive They are not as quite as timing belts but can be used for larger torques English for Mechatronics Engineering 60 CHAINS VERSUS BELTS Drive chains are most often made of metal, while belts are often rubber, plastic, or other substances Although well-made chains may prove stronger than belts, their greater mass increases drive train inertia Drive belts can often slip (unless they have teeth) which means that the output side may not rotate at a precise speed, and some work gets lost to the friction of the belt against its rollers Teeth on toothed drive belts generally wear faster than links on chains, but wear on rubber or plastic belts and their teeth is often easier to observe Conventional roller chain drives suffer the potential for vibration, as the effective radius of action in a chain and sprocket combination constantly changes during revolution If the chain moves at constant speed, then the shafts must accelerate and decelerate constantly If a drive sprocket rotates at constant RPM, then the chain (and probably the driven sprocket) must accelerate and decelerate constantly This is usually not an issue with many drive systems, however most motorcycles are fitted with a rubber bushed rear wheel hub to virtually eliminate this vibration issue Toothed belt drives are designed to avoid this issue by operating at a constant pitch radius Chains are often narrower than belts, and this can make it easier to shift them to larger or smaller gears in order to vary the gear ratio Multi-speed bicycles with derailleurs make use of this Also, the more positive meshing of a chain can make it easier to build gears that can increase or shrink in diameter, again altering the gear ratio Both can be used to move objects by attaching pockets, buckets, or frames to them; chains are often used to move things vertically by holding them in frames, as in industrial toasters, while belts are good at moving things horizontally in the form of conveyor belts It is not unusual for the systems to be used in combination; for example the rollers that drive conveyor belts are themselves often driven by drive chains Drive shafts are another common method used to move mechanical power around that is sometimes evaluated in comparison to chain drive; in particular shaft English for Mechatronics Engineering 61 drive versus chain drive is a key design decision for most motorcycles Drive shafts tend to be even tougher and more reliable than chain drive, but weigh even more (robbing more power), and impart rotational torque Virtually all high performance motorcycles use chain drive, with shaft driven arrangements generally used for many non-sporting machines Toothed belt drives are used for many lower power motorcycles English for Mechatronics Engineering 62 CHAPTER 5: BEARINGS Whenever there is relative motion of one surface in contact with another, either by rotating of sliding, the resulting frictional forces generate heat which wastes energy and results in wear The function of a bearing is to guide with minimum friction and maximum accuracy the movement of one relative to another Of particular importance is the need to give suitable support to rotating shafts, i.e support radial loads The term thrust bearing is used for bearings that are designed to withstand forces along the axis of a shaft when the relative motion is primarily rotation There are two common type of bearing, which are ball bearing and roller bearing With this type of bearing, the main load is transferred from the rotating shaft to its support by rolling contact rather than sliding contact A rolling element bearing consists of four main elements: an inner race, an outer race, the rolling element of either balls or rollers, and a cage to keep the rolling element apart The inner and outer races contain hardened tracks in which the rolling elements roll There are a number of forms of ball bearings and roller bearings: English for Mechatronics Engineering 63 DEEP-GROOVE This is good at withstanding radial loads but is only moderately good for axial loads It is a versatile bearing which can be used with a wide range of load and speed Deep Groove Ball Bearings are cost-effective and maintenance free They are basically used when axial loads from two directions have to be transmitted & there is not enough space to allow installation of matched spindle bearings and when speed is less important when compared to required guidance of the rotating parts Physical Characteristics  Comprises of deep uninterrupted raceways  Ring grooves are circular arcs made slightly larger than the radius of the ball  The balls make point contact with the raceways  The inner ring shoulders are of equal height Advantages of Deep Groove Ball Bearings  Sustain radial, axial, or composite loads  Provide both high-running accuracy & high-speed operation  Can replace high speed angular contact ball bearings  Simple design  Maintenance free  Longer service life English for Mechatronics Engineering 64 FILLING - SLOT Filling slot bearings have a higher radial load carrying capacity than bearings without filling slots, but their axial load carrying capacity is small They are also unable to operate at such high speeds as bearings without filling slots Depending on the main application for which they are used, deep groove ball bearings with filling slots have a cage or no cage The raceways in both of the rings are in arc groove form, which can carry radial and axial load in double directions They can be applied in situations where highrotating speed and low noise and low vibration are required When the outer diameter is less than (inclusive) 400mm, they use pressed cage with steel sheet When the outer diameter is bigger than 400mm, they use brass cages Can be found in automobiles, machine tools, motors, instruments, construct machines, railway vehicles, agricultural machines and various other special machines ANGULAR CONTACT This is good for both radial and axial loads and is better for axial loads than the deep-groove equivalent The angular contact ball bearing is termed thrust ball English for Mechatronics Engineering 65 bearing Because doing so can fill many precious metal balls, the load capacity of that diameter is definitely greater than that of the common impact At the same time it may possibly support a really great axial fill or absolute axial load Relatively, it’s doing work rotate velocity is similar to that relating to deep rhythm ball showing but its muscle is more demanding than the deep groove a single When people mount the angular contact ball bearing, it should be set up effectively because this bearing is very sensitive to the error in the axial line In the common predicament, this displaying is not used to help alone offer the radial load Whether it is used to tolerate the radial download, it must add to the axial load Design Attributes  Specific geometry of angular contact bearing raceways and shoulders creates ball contact angles that support higher axial loads  Expanded options include special lubricants, cage materials, preloads and coatings for additional corrosion resistance Applications Angular contact ball bearings are engineered for use in high-speed, high precision applications for:  Agriculture  Chemical  General industry  Utilities English for Mechatronics Engineering 66 DOUBLE-ROW Double row deep groove ball bearings feature higher load ratings than single row bearings, but are very sensitive to misalignments These bearings have deep uninterrupted raceways and high conformity between the balls and raceways Besides this, Double Row Deep Groove Ball Bearing is able to carry axial loads acting in both directions in addition to radial loads Features: - Deep groove ball bearings mainly take radial load as well as take moderate axial load - With less coefficient of friction, high limiting speed, large size range and various structure - They are suitable of precision instruments, low noise motors, automobiles, motorcycle, and other common machinery - A widely used type of bearings in machinery industry Applications: Double-row deep-groove ball bearings are engineered for use in electric motors, automotive applications, home appliances, industrial equipment English for Mechatronics Engineering 67 SELF-ALIGNING Single-row bearings can withstand a small amount of shaft misalignment but where there can be serve misalignment a self-aligning bearing is used They are suitable for applications where misalignment can arise from errors in mounting or shaft deflection The steel balls, cage, and inner ring can rotate freely at a certain angle, as it is stated that the bearings have self-aligning features Accordingly, misalignment of the bearing shaft due to the machining and installation of the shaft and housing will be automatically adjusted Physical Characteristics  The self-aligning ball bearing has two rows of balls  A common concave sphere raceway in the outer ring  The center of whose curvature meets that of the bearing itself, so that the inner ring, balls and cage continue to rotate  The self-aligning ball bearing with a tapered bore can easily be fit to the shaft with an adapter assembly Advantages of Self Aligning Ball Bearings  Have the lowest friction of all rolling bearings  Run cooler even at high speeds  Easy mounting and dismounting  The permissible operating speed is not dependent on the common criteria like heat generation or cage stability and strength Application of Self Aligning Ball Bearings  Self-aligning ball bearings are used for commercial ground shafting applications  Since axial load capacity is limited, self-aligning ball bearings are not suitable for applications with heavy axial loads English for Mechatronics Engineering 68 All bearing products are popular among different industries They have various characteristics and functions Compared to ball bearings, roller bearings have higher radial load capacity Roller bearings can be future divided into many types When compared to the same-sized sleeve bearings, they are capable of higher rotational speeds STRAIGHT-ROLLER BEARING The straight-roller bearing has a larger carrying capacity of axial load compare with the deep-groove ball bearings The structure of the bearing shows that it runs very well under high rotational speed It is a separable bearing It is especially convenient for the assembly and disassembly It has advantages in a condition that the interference is required and assorted with inner ring, outer ring and housing Also, it will carry a greater load than ball bearings of the same size because of their greater contact area However, they are not tolerant of misalignment Straight roller bearings mostly consist of three main sections: The inner bearing race fits snugly on the turning shaft, or can actually be the shaft itself if the shaft metal is hard enough The outer race is a uniform and hardened collar that fits inside the bearing holder bore Finally, there should be a sufficient number of uniform English for Mechatronics Engineering 69 straight rollers to completely fill the space between the two races without binding together These bearings will last almost forever if sealed, kept very clean, and lubricated with high film strength-bearing grease This type of bearing product has various applications They are suitable for electric motors, automobiles, transmission shafts, gear shafts and so on On vehicles, they are ideal axle bearings for dump trucks, cement mixers, bulldozers, load haulers, and lifts Besides, they can also be applied in very large industrial machines such as presses, forges, conveyors, gear boxes and rolling mills, etc TAPER ROLLER Tapered roller bearings are separable bearings, bearing inner and outer rings with tapered raceways are, for the circular conical roller Roller in line contact with the raceway, can withstand heavy radial and axial joint load, but also bear the pure axial load Contact angle decreases, the higher the axial load capacity The taper roller bearings can carry combinations of large radial and thrust loads or thrust load only Because of the difference between the inner and outer raceway contact angles, there is a force component, which drives the tapered rollers against the guide flange The relatively large sliding friction generated at this flange makes this bearing typically unsuitable for high-speed applications without special English for Mechatronics Engineering 70 consideration to coolant / lubricant Typical applications include construction machinery, gear construction, vehicle manufacture and rolling mills Physical Characteristics of Taper Roller Bearings  Taper roller bearings have tapered inner and outer ring raceways between which tapered rollers are arranged  The projection lines of all the tapered surfaces meet at a common point on the bearing axis Their design makes taper roller bearings particularly suitable for the accommodation of combined (radial and axial) loads  The axial load carrying capacity of the bearings is largely determined by the contact angle The larger the angle, the higher the axial load carrying capacity  Taper roller bearings have the logarithmic contact profile that provides for optimum stress distribution over the roller/raceway contacts  The special design of the sliding surfaces of the guide flange and large roller ends considerably promotes lubricant film formation in the roller end/flange contacts Advantages of Taper Roller Bearings  Dimensional Stability  Long Life Even In Contaminated Lubricant  Durable Steel Cage  Dimensionally Interchangeable With Other Bearing Manufacturers Applications of Taper Roller Bearings  In many applications taper roller bearings are used in back-back pairs so that axial forces can be supported equally in either direction  Pairs of taper roller bearings are used in car and vehicle wheel bearings where they must cope simultaneously with large vertical (radial) and horizontal (axial) forces  Agriculture, Construction and Mining Equipment  Various Axle Systems  Conveyance Vehicles  Gear Box, Engine Motors, Reducers Taper Roller Bearings Design English for Mechatronics Engineering 71 Tapered roller bearings consist of four basic components including the cone (inner ring), the cup (outer ring), tapered rollers, and a cage (roller retainer) Tapered roller bearings are designed such that their conical rollers and raceways are arranged so that all elements of the roller and raceway cones meet at a common apex on the bearing axis The rollers are guided by the contact between the large end of the roller and the rib on the inner ring (cone) This construction provides a high capacity for radial loads, axial loads, and combined loads The larger the contact angle, the greater the loading capacity becomes When a pure radial load is placed on the bearing, an induced load in the axial direction is also generated So, these bearings are generally used in pairs opposing each other Proper running clearance or preload can be obtained by adjusting the distance of the two bearings against one another Since the inner (cone) and outer (cup) rings are separable, each ring can be mounted individually, allowing both rings to use tight fitting practices, if desired NEEDLE ROLLER Needle roller bearings use needle rollers as rolling elements The needle rollers are a maximum of mm in diameter and are to 10 times as long as they are in diameter Because the bearings use needle rollers as rolling elements, the crossEnglish for Mechatronics Engineering 72 section is thin, but they have a high load capacity for their size Because of the large number of rolling elements, the bearings have high rigidity and are ideally suited to wobbling or pivoting motion Physical Characteristics  Its cylindrical rollers, which are thin and long in relation to their diameter They are referred to as needle rollers  Needle Rollers are used for needle roller bearings and are rigid and highly accurate  In spite of their low cross section the bearings have a high load carrying capacity  Available with or without an inner ring  The needle rollers are a maximum of mm in diameter and are to 10 times as long as they are in diameter Application of Needle Roller Bearings Needle roller bearings contain precision needle rolling elements, which have multiple uses in a variety of industries including automotive, truck, farm and construction equipment, two-cycle engines, outboard engines and consumer durables Needle rollers are mainly used as bearing rolling elements to transmit torque and reduce friction They can also serve as precision shafts or as precision locating pins Other uses for needle roller bearings include crank pins, precision shafts and as locating pins Advantages of Needle Roller Bearings  Due to the smaller cross-section, greater rigidity, higher load-carrying capacity and lower inertia of the needle roller bearings help size and weight reductions in the machinery  Though they are less wide, their load carrying capacity is high and is most suitable for applications where the load is high and the radial space is less  Needle roller bearings, which are designed to withstand oscillation can operate under severe conditions and interchange with sliding bearings English for Mechatronics Engineering 73 Typical Applications  Transmissions, transfer cases, engines and valve trains  Steering and braking systems  Axle support  Outboard engines  Power tools  Copiers, fax machines, paper-moving equipment  Appliances Expanded Options  Assemblies with bearings  Engineered polymer cages  Bearings with one or two seals  Closed end bearings  Oil holes  Drawn sleeves Types of Needle Roller Bearings Different types of Needle roller bearings involved in general engineering are:  Drawn cup needle roller bearings  Drawn cup needle roller bearings with closed ends  With and without inner rings English for Mechatronics Engineering 74