Tablet-Machine-Design-specification毕业论文.docx

Term Project on Machine DesignTerm Project on Machine DesignDesign SpecificationProject: Working mechanism for tablet machineSchool: Designer: Student Number: 1120133852Class Number: 30011301Course Teacher: 2016-1-1Contents1. Introduction41.1 Design background41.2 Design requirements51.3 Given conditions61.4 Design tasks62. Driving mechanism graphs of main mechanisms72.1 Mechanism of upper indenter72.2 Mechanism of bottom indenter82.3 Feed mechanism83. Reducer scheme of the transmission device84. Selection of the AC motor84.1 Calculating the motor power we need84.2 Choosing the motor we used in our project95. Determining the systems transmission parameters and dynamics parameters105.1 Transmission ratio allocation105.2 Determining different shafts dynamics parameters115.2.1 The rotation speed of each shaft115.2.2 The transmitted power of each shaft115.2.3 The input torque of each shaft126. Transmission parts design of the reducer126.1 The V-belt design between motor and input shaft126.2 The V-belt design between output shaft and feed mechanism156.2.1 The chain design166.3 The helix gears transmission parts design in reducer176.3.1 Design of the high-speed level helix cylindrical gears176.3.2 Design of the low-speed level helix cylindrical gears257. The shaft systems design and strength check347.1 The high-speed shaft (Shaft I) design and calculation347.2 The intermediate shaft (Shaft II) design and calculation447.3 The low-speed shaft (Shaft III) design and calculation558. The casing design639. Design summary6510. Acknowledgement6611. References66PrefaceAs students of Mechanical Engineering or machinery related major, mechanical design theory and machine design practice are of great importance for all of us. The term project on machine design is an advanced course on modeling, design, integration and best practices for use of machine elements such as bearings, gears, shaft, bolts, cams and mechanisms. It can not only help us to reinforce the knowledge studied from Mechanical Graphics, Theory of Machines & Mechanisms, Machine Design, etc, but also can urge us to practice the principles of mechanical design. By studying this practice course, we will know well the design process of mechanical system, and can develop the ability of modeling, analysis, also the innovation ability as well.1. Introduction1.1 Design backgroundThe tablet machine is a common but important machine used in tablet manufacturer, what the simplified model is shown in Figure 1-1. Under the cooperation of feed mechanism, mechanism of upper indenter and mechanism of bottom indenter, the tablet machine can achieve feed the powder, press the powder to be tablet. The working process is depicted in Figure 1-2. Figure 1-1 The simplified model of tablet machineFigure 1-2 Working process of pressing powder1.2 Design requirementsIts easy to find that the tablet machine is a machine which has very high demand for the cooperation work of different mechanism motions. There are feed mechanism, mechanism of upper indenter and mechanism of bottom indenter in this machine, and the motion relationship of these mechanism should like the Figure 1-3 shows.Figure 1-3 Sketch for working cycleTherefore, this system should have three working actuator, in order to use one motor to actuate this machine, we need to connect the driving link together just like Figure 1-1 presents.What the main task of this design project is the reducer design to obtain suitable speed to drive the machine.1.3 Given conditions1. Input: three-phase AC induction motor: 1500rpm2. Maximum resistance force during working , the thickness of die is 50mm, the thickness of tablet is 3mm, pressing distance is 38mm, pressing process lasts 1/6 cycle.3. Productivity: tablets/min, which just is the frequency of indenter movement.4. 90% reliability, the required life is 10 years, 300 days for each year and 1 shift (8 hours) per day. That is the working life should no less than hours.5. The efficiency from output shaft of reducer to upper indenter is 0.65, to bottom indenter is 0.65, to feeding is 0.75. Efficiency of belt drive is 0.96, for a pair of ball bearing is 0.99, for a pair of roller bearing is 0.98, for a pair of gear is 0.99, and for a coupling is 0.980.99.1.4 Design tasks(1) Design the driving mechanisms for upper indenter, bottom indenter and hopper, and give its mechanism graph(2) Design the reducer includes: Design the structure of reducer Design the related mechanical elements(3) Submitted materials Assembly drawing for reducer Totally 3 engineering drawings for typical elements Design specification2. Driving mechanism graphs of main mechanisms2.1 Mechanism of upper indenterWe use crank-rocker mechanism to achieve the motion of upper indenter. What the mechanism graph is like Figure 2-1.Figure 2-1 Upper indenter mechanism graph Figure 2-2 Bottom indenter mechanism graph2.2 Mechanism of bottom indenterThe cam mechanism is used to push the bottom indenter go up or go down. The mechanism graph is shown in Figure 2-2.2.3 Feed mechanismWe also use cam/follower in feed mechanism to achieve reciprocating motion of the hopper. The mechanism graph is shown as below.Figure 2-3 Feed mechanism graph3. Reducer scheme of the transmission deviceFrom the tasks allocation, the V-belt and cylindrical gear are used in reducer. And due to helical gear has advantage of with big contact ratio and transmit smooth and steady, we choose two pairs of helical gears in reducer.4. Selection of the AC motor4.1 Calculating the motor power we needThe tablet machine cycle is , while the press tablet process spend cycle, its .Because the efficiency of the upper indenter and bottom indenter are the same. So we can use the relative speed to calculate the application power. The relative speed of the upper indenter with respect to bottom indenter is So the application power is .We already known there are two pairs of gears, three pairs of bearings in the reducer. And there is a belt between motor and reducer input shaft. And a coupling is need in output shaft. So the total efficiency of the machine isWhere the efficiency of these parts are presented in given conditions before.So the motor power is .4.2 Choosing the motor we used in our projectConsidering the motor power and the synchronous speed of the motor . From the Machine Design Manual, we can choose the corresponding three-phase asynchronous motor in our project. What the parameters of the motor are shown as below.Motor typerated power/kwfull-load speed/rpmlocked torquemaximum torquemass/kgY90L-41.514002.22.327Table 4-1 Parameters of the motor used in project5. Determining the systems transmission parameters and dynamics parametersFigure 5-1 The main transmission scheme of the reducer5.1 Transmission ratio allocationThe whole transmission ratio is And the transmission ratio is consists of three parts . Where is V-belt transmission ratio, and are the high-speed level and low-speed gear transmission ratio respectively.We can let .From experienced formula So we can let , then .5.2 Determining different shafts dynamics parameters5.2.1 The rotation speed of each shaftWe already known output shaft rotation speed ,Shaft II Shaft I 5.2.2 The transmitted power of each shaftShaft I Shaft II Shaft III 5.2.3 The input torque of each shaftShaft I Shaft II Shaft III ContentsRotation speed/rpmPower/WTorque/N.mShaft I700144019.646Shaft II156.251411.3486.261Shaft III501382.26264.202Table 5-1 The systems transmission parameters and dynamics parameters6. Transmission parts design of the reducer 6.1 The V-belt design between motor and input shaft1. Known conditionsThe rated power of motor used in this reducer is , and the rotation speed is . The transmission ratio of the input V-belt is .2. Determining calculation power Considering the work conditions, we can let work condition coefficient .So 3. Choosing V-belt typeOn the basis of and , and considering the power is so small in this reducer. We select the type A V-belt.4. Determining pulley datum diameter , According to Machine Design Manual, we let .So the diameter of driven pulley .5. Computing the belt speed Because , its suitable.6. Determining center distance and belt datum length Initially determining center distance Thats So we can initially let .The belt initial datum length From related table, we choose the datum length .So the actual center distance is The minimum center distance when assembled, and the maximum center distance when adjusted are7. Check the small pulley contact angleDue to , its suitable.8. Calculating the number of V-belt we needFrom the Machine Design Manual, we can obtain that the basic rated power is , the rated power increment is , the wrap angle coefficient is , and the length coefficient is .So the number of V-belt we need isSo we let the number of V-belt we need is .9. Determining initial tensile force and pressure force on the shaft IInitial tensile force: Where is the mass of unit length V-belt.So the pressure applied on the shaft I is6.2 The V-belt design between output shaft and feed mechanism1. Known conditionsThe rated power of output shaft is , and the rotation speed is . The transmission ratio of the output shaft V-belt is .2. Determining calculation power Considering the work conditions, we can let work condition coefficient .So 3. Choosing V-belt typeOn the basis of and , and considering the power is so small in this reducer. We select the type B V-belt.4. Determining pulley datum diameter , According to Machine Design Manual, we let .5. Computing the belt speed Because is so small, its unsuitable to use V-belt here, we have to use chain transmission.6.2.1 The chain design(1) Known conditionsThe output shaft (shaft III) power is , the rotation speed of the two chain wheels are , the transmission ratio is .(2) Choosing tooth number of chain wheelAccording to Machine Design Manual, we can let tooth number is .(3) The calculation powerWhere , , , are coefficients that can be found in Machine Design Manual.(4) Determining chain type and chain pitchChoosing the chain type is 12A, so the chain pitch is . The width of chain is appropriately 18mm.(5) Calculating chain speed6.3 The helix gears transmission parts design in reducer6.3.1 Design of the high-speed level helix cylindrical gears1. Choosing the gears materials and heat treatment methods(1) The following table is the selection of gearsTable 6-1 The selection of the high-speed level gearsGear typesMaterialsHeat treatment methodsHardnessBig gear(gear 1)40 CrThermal refining270 HBSPinion(gear 2)45 steelNormalizing195 HBS(2) The limit stressAccording to related table and figure, we can find that:, , , (3) The reliabilityDue to the 90% reliability, we have .2. Design the main size on the basis of gear contact fatigue strengthThe simplified design equationWhere is the center distance between two meshed gears. And(1) The pinion torque .(2) Gear tooth number ratio .(3) Coefficient of gear facewidth .(4) Loading coefficient .(5) Choosing So Due to , so applying the to calculate aSo we choose the center distance .(6) According the experienced equation to choose the moduleSo we select the standard module is .(7) Calculate the main geometric parametersInitially choosing helix angel is .Tooth number So we choose the gear tooth number are separately.The transmission ratio error:Calculating the helix angle exactly:So the pitch diameter of gear 1 and gear 2 are:Big gear: Pinion gear: The addendum circle diameter:Big gear: Pinion gear: (8) Calculate the tooth widthBecause the tooth width of pinion is usually wider than the big ones to mesh better, so we have (9) Calculate the equivalent tooth number(10) The contact ratio(11) Calculate the circular velocity3. Check the gear surface contact fatigue strength(1) Gear surface contact fatigue allowable stressNumber of stress cycles:Where j represent whether the motor rotates single or double direction. In this project, the motor just rotates at one direction, so j=1.Choosing the motion viscosity of lubrication oil is .The following parameters and coefficients can be found in machines manual., , So the allowable stress is:(2) Gear surface contact fatigue stressThe tangential force:The following parameters and coefficients can be found in machines manual.So the gear surface contact fatigue stress is:(3) Check the strengthDue to So the gear surface contact fatigue stress satisfies the requirement.4. Check the gear root bending fatigue strength(1) The gear root bending fatigue allowable stressThe following parameters and coefficients can be found in machines manual.So the allowable stress:(2) The gear root bending fatigue stressThe following parameters and coefficients can be found in machines manual.So the gear root bending fatigue stress is:(3) Check the strengthDue to The gear root bending fatigue stress satisfies the requirement.Table 6-2 High-speed level helix cylindrical gear transmission related parametersContentsCalculation formulasCalculation resultsTransmission ratio4.48Center distance110mmStandard module2mmHelix angleTooth number2089Pitch diameter40.367mm179.633mmAddendumcircle diameter44.367mm183.633mmTooth widthb151mmb244mm6.3.2 Design of the low-speed level helix cylindrical gearsNote: The following design process is very similar to the previous one, so we use the subscript 1 and 2 to represent the gear 3 and gear 4 separately.1. Choosing the gears materials and heat treatment methods(1) In order to product the gears conveniently, we choose the same materials in the low-speed level gears.Table 6-3 The selection of the low-speed level gearsGear typesMaterialsHeat treatment methodsHardnessBig gear(gear 3)40 CrThermal refining270 HBSPinion(gear 4)45 steelNormalizing195 HBS(2) The limit stressAccording to related table and figure, we can find that:, , , (3) The reliabilityDue to the 90% reliability, we have .2. Design the main size on the basis of gear contact fatigue strengthThe simplified design equationWhere is the center distance between two meshed gear3 and gear 4. And(1) The pinion torque .(2) Gear tooth number ratio .(3) Coefficient of gear facewidth .(4) Loading coefficient .(5) Choosing So Due to , so applying the to calculate aSo we choose the center distance .(6) According the experienced equation to choose the moduleSo we select the standard module is .(7) Calculate the main geometric parametersInitially choosing helix angel is .Tooth number So we choose the pinion gear tooth number is .So we choose the gear tooth number .The transmission ratio error:Calculating the helix angle exactly:So the pitch diameter of gear 3 and gear 4 are:Big gear: Pinion gear: The addendum circle diameter:Big gear: Pinion gear: (8) Calculate the tooth widthBecause the tooth width of pinion is usually wider than the big ones to mesh better, so we have (9) Calculate the equivalent tooth number(10) The contact ratio(11) Calculate the circular velocity3. Check the gear surface contact fatigue strength(1) Gear surface contact fatigue allowable stressNumber of stress cycles:Where j represent whether the motor rotates single or double direction. In this project, the motor just rotates at one direction, so j=1.Choosing the motion viscosity of lubrication oil is .The following parameters and coefficients can be found in machines manual., , So the allowable stress is:(2) Gear surface contact fatigue stressThe tangential force:The following parameters and coefficients can be found in machines manual.So the gear surface contact fatigue stress is:(3) Check the strengthDue to So the gear surface contact fatigue stress satisfies the requirement.4. Check the gear root bending fatigue strength(1) The gear root bending fatigue allowable stressThe following parameters and coefficients can be found in machines manual.So the allowable stress:(2) The gear root bending fatigue stressThe following parameters and coefficients can be found in machines manual.So the gear root bending fatigue stress is:(3) Check the strengthDue to The gear root bending fatigue stress satisfies the requirement.Table 6-4 Low-speed level helix cylindrical gear transmission related sizeContentsCalculation formulasCalculation resultsTransmission ratio3.125Center distance150mmStandard module2mmHelix angleTooth number36113Pitch diameter72.483mm227.516mmAddendumcircle diameter76.483mm231.516mmTooth widthb367mmb460mm7. The shaft systems design and strength check7.1 The high-speed shaft (Shaft I) design and calculation1. The known conditions Due to gear 1 diameter is so small, we can make shaft I be gear shaft. The root circle diameter of it is .The belt pulley attached to shaft I is determined in V-belt design part, the width of it is 18mm from Manual Book.The power transmitted by shaft I is . The rotate speed of shaft I is .The hel