Simulation and analysis of breechblock mechanism

Joural of Marine Science and Application ,Vol.5 No. I ,March 2006 pp. 48 -52Simulation and analysis of breechblock mechanismLUO A-ni ,HU Sheng-hai LIU He-ping and ZHANG Jia-taiSchool of Mechanical and Electrical Engineering , Harbin Engineering University , Harbin 150001 , ChinaAbstract .This paper analyzes the motion state and forces of the warship gun breechblock cam. Firstly ,the method of driven cam locking the breechblock safely and reliably can be obtained through analyzingthe force between the driven cam and breechblock. And then according to the geometry and motion rela-tionships between the driving cam , driven cam and stopper , the angular range of camns and the instanta-neous angular velocity of driven cam are obtained. Finally ,with the specific velocity , the velocity-accel-eration curve at the head of the driven cam can be obtained by simulating with the Adams software. Itcan ensure that the driven cam can make the part driven certain velocity in a short time and cannot de-form plastically.Keywords naval gun ; lock-breechblock ; cam ; rillry cartridge extractorCLC number :TJ302Document code :AArticle ID 1671 - 9433( 2006 )01 - 0048 -051 Introductionat an angle. Partl which makes the cartridge case tou-ch with the end of partl ,is pushed by part3 to rotateIn the shooting system of the navalun , the require-rapidly. External force pushes part2 to move down.ment for the motion accuracy of its mechanism is strictAfter part3 gets to the surface of part4 , the springin manufacturing and assembling. But the mechanismdrives part2 to move up rapidly. Part2 is blocked byof the warship gun moves to-and-fro at a high velocity ,hook of partl. Part3 glides on the surface of part4 , andthe impacts between some parts influence the accuracykeeps relatively stationary at an angle ,so part2 isof the motion because of their elastic and plastic de-blocked by partl. When part3 moves to the left side offormations in parts. So ,it is essential to research thepart 4 , the gun body , on which part1 , part2 and part3kinematics and dynamics of the key parts. Accordingre fixed ，moves right. After part3 impacts part4to the results , these important parts are corrected dur-part3 rotates clockwise to original position in order thating manufacturing , assembling and operation , the ac-partl rotates anticlockwise. Part2 is driven to move upcuracy of the motion is improved. [ 11by the spring. These parts move periodically. The to-and-fro velocities of partl , part2 and part3 can reach2 Analyzing the function of the driven2.6 m/s , which is bound to result in impacting.As is shown in Fig. 1 ,part2 moves upwards quickly bycam blocks breechblockthe action of spring force , after part2 impacts partl ,Fig. 1 shows the structure of breechblock. In the struc-the impact force makes partl rotate anticlockwise 2ture part4 is fixed ,part 1 , while part2 and part3 moveThen partl cannot lock part2 , namely breechblock willto-and-fro together with the gun body. Partl , part3 canmove up still. If such a thing happens , then the nextrotate around their axes respectively ，and part2 canshell cannot be put into gun barrel , which will influ-move around vertical direction. When part1 ,part2 andence the smooth operation of the whole system. So it ispart3 move from left side to right side of part4 , part3necessary to ma中国煤化工ler to avoidkeeps in touching with part4 , and rotates anticlockwisesuch phenomenacting onTYHC NMH G^Received date 2005 -06 -28.Foundation item Supported by Harbin Engineering University Fund Projee( NO. HEUFT05071 )..LUO A-ni et al :Simulation and analysis of breechblock mechanism19.breechblock. Fig. 2 ( a ) is the ideal situation. Suchthis way , the angle can ensure the fulillment of loc-impact can make the driven cam lock breechblock reli-king the breechblock safely and reliably.able. Since such force can produce a torque , it drivesthe driven cam to rotate clockwise. Thus the driven3 Analysis on the motion on lock-cam can lock the breechblock more tightly. Mean-breechblock' s camswhile ,if the impact force is the same as Fig. 2( b )shows , the bad results will happen. Because of the an-Fig.3 is the sketch of the cam mechanism. Accordingticlockwise torque , driven cam rotates and makes theto the analysis and the calculation , the mutual impactsspace for breechblock moving continually upwards.among the driving cam , the stopper and the driven camThe mechanism work invalidation , the next shell can-take place on three sections of arcs , the centers ofnot be put.(3]which are the points a a2 and az. The coordinates ofaa2anda3are(x)(Ya)(xn)(Yar)and.(x。)( ya ) respectively. The impact of the drivingcam and the stopper happens on two sections of arcswhose point of intersection is( xapr )(yap ). So whenthe driving cam touches the stopper , its maximal rota-ting angle is0m = arccos.. arctan-"I .arccos(1)1. Driven cam ;2. Breechblock ;√xi +y2Yo23. Driving cam ;4. Limiting position stopperThe angular range of the driving cam is[0 .. ]Fig. 1 Structure of breechblock+a( a )The ideal situation ( b ) The bad resultsFig.2 Forces of stopper on driven camGaFig. 3 Coordinates of the camsThus ,if part3 is demanded to move around the uppersurface of par14 , partl ( driven cam ) can lock part2( breechblock ) , the impact force must be around the3.1 The instantaneous angular velocity of thedriving camleft side of axis. That is to say , the force should pro-duce clockwise torque. Such clockwise torque needsIt is assumed that the pair of cams doesn' t translate,the hook on the driven cam to ensure it. It is to saybut rotate around their own axes , and then the stopperthat the hook on the partl can not be more than 90 de-will translate rightward in motion. The velocity of thegree. Meanwhile , in order to lock the part2 , the anglestopper motion中国煤化工isI(x v)is the coordinat5pact point ,of the hook should not too small. After simulating , the( x vo)is the inuan pount ul Ilitietiunl of the stop-:0HCNMHGangle range should keep between 84 and 87 degree. Inper and the driving cam. The relation of geometry gives50.Journal of Marine Science and Application ,Vol.5 No. I ,March 2006the instantaneous rotating angle of the driving cam ,yo -rsin(βm + arctan")尸=θ = arctan以十x0- arctan(2)(x。-x。) +(ya-ya )(4)The instantaneous angular velocity of the driving cam iswhere Bβm.. is the maximal value of rotating angle of theo=(3)driven cam. Soβ can be solved from Eq.(4 ), and the .√x+y cos0range of angular motion of the driven camis[0 B ]3.2 Determination of the angular range of the3.3 Obtaining the instantaneous situation of thedriven camThe driving cam and the driven cam mesh on two sec-It is supposed that the coordinates of the instantaneoustions of arcs , with centers being respectively point azpoint of intersection of the cams is( x y ). Becauseand point as. The coordinates of az and as are( xo3 ,the two arcs are always tangent with each other duringYag)(xo yn),the radi are ras and ras respectively. .the motion , the point of intersection must be on theHence , the following relation can be obtained from theline between the two centers. According to the geome-geometry and motiontry and motion relation of the cams mechanism , the fol-(r。co( 0.. + arctan)+lowing relation can be obtained :(raysir( 0m + arctan )rqgcos(β + arctan- )- ra3 cos( a + arctan 一)x - ro,cos( a + arctan .)xo4xa3kyas + ra,sin( β + arctan一- ragsin( a + arctanra.sin( β + arctan(5)|(x -rgco<(a + arctan-)) +(yu -gsin(a + arctan二)) =的On the driving cam , the velocity UI of the contact pointSo , the linear velocity of the contacting point of theof the set of cams isdriving cam and the driven one can be got ,D. =w√(x-x户+(y-yY =”√(x-x) +(y-yYco<γ +90°-品√(x1-x) +(yr-yY.(6)y1-147、(x y) is the coordinates of the contact point of thearctanxstopper and the driving cam.(8)The direction angle isThereby , the angular velocity w1 of the driven cam is .γ = 90°- arctan().(7 )-√(x -xY +(y1 -yYco(γ + 90° - arctan)-。-( rcos( 90° - arctan二usy0| =-(9)√++(y-→y)If the distance between the tip point a6 of the drivenFig.3 ,the instantaneous velocity 0。6 of the point a6 oncam and the center of the driven cam is L ,as shown inthe driven cam will be”(x-x) +(yx-yFco<(γ +90° - arctan-“)-。中国煤化工“))√行+(y-。严MYHC NMHG L.( 10).LUO A-ni et al :Simulation and analysis of breechblock mechanism51.The derivative of the expression of the instantaneousthe moving method as its actual behavior. Now thevelocity with respect to time leads to the instantaneousmodel can be simulated.acceleration of this point. Again , based on the mass ofthe driven part that the driven cam pushes and its re-Fig. 5( a ) shows the velocity of the point a6 on thesistance , the force on the point a6 can be found. Thendriven cam. Fig. 5( b ) shows the acceleration at the .from the force , the elastic force and plastic deformationpoint a。of the driven cam. According to the figures ,when l≤0. 015 s , the velocity and the accelerationof the driven cam can be determined.both have the vibration characteristics. When t≥0.015 s ,the velocity is 2.6 m/s stably , and the accel-4 The simulation of the set of camseration is 0 stably. The maximal velocity of the pointAccording to the analysis above , the simulation modela6 on the driven cam can reachv= 18.5 m/s ;its maxi-mal acceleration can reach a =7. 8 x 10'm/s?. Theis made up. The Adams software can make it intuition-istic to study the kinematics and dynamics of the mech-force F on the head a6 of the driven cam isF= ma+ F.(11 )anism. But Adams is not good at three-dimensionalmodeling ; PRO/E may be combined to build up lock-The m is the mass of the objects which the driven cambreechblock simulation. Firstly ，all parts of lock-pushes ,F，is the resistance on these objects. Thebreechblock and assemble are built up , then introducecheck-up calculation is carried out based on these val-the simulation model to ADAMS and add motion joint.ues. The check-up suggests that the driven cam can' tFig. 4 shows the ultimate simulation model. Each partexperience plastic transformation.is built as it does in the actual situation. And they arex10°assigned with the same materials as the fact. ThenPRO/E can offer the parameters such as exact mass ,s.0inertia , center of mass etc for every part. After intro-ducing into ADAMS , those parameters still exist , sotill now simulation can be carried out [4-61.-650.010.02 0.03 0.04( a) The velocity of point a6MFig.4 The simulation model of the pair of camThe stopper is fixed to the ground ,so that it is move-050.02sless during simulating ; two cams lock-breechblock are( b ) The acceleration of point a。supposed to be connected with the gun body by two ro-Fig. 5 The velocity and acceleration at the point of thetation joints ; the breechblock is connected with the gundriven cambody by translation joint ; the gun body is connected tothe ground with translation joint ,so that it can move中国煤化工directly ; with two cams connected with cam joint , the5 ConlusionYHCNMHGconnection mode is assumed to be CURVE T0The lock-breechblock mechanism is analyzed in thisCURVE. After the joints added , the gun body is given52.Journal of Marine Science and Application ,Vol.5 No. I ,March 2006paper. At first , the angle range of the hook on theLUO a-ni was borm in Shanxi , in 1978 ,driven cam is obtained based on the analyzed theoreti-China. She received the bachelor' s de-gree in Mechanical Design and Manufac-cally. The result gives important message that the angleture and M. S. degree in Mechanical Derange should be in 84 - 87 degree. In this range , thesign and Theory from Harbin Engineeringbreechblock impacts the hook , and then the moment isUniversity in 2000 and 2003 , respective-produced , which can make the hook rotate to blockly. She began to work as a PH. D candidate in the School of Me-breechblock direction. This angle range is very mean-chanical and Electrical Engineering in 2002 , in Harbin Engi-ingful to improve the lock-breechblock mechanism.neering University. Her current researches focus on the navalThe velocity of input and output is calculated. Thengun shell-feeding system and its virtual prototype technology etc.these two velocities are compared and it can be foundHer main research aspects : mechanical design , vitual prototype .that the output velocity is 7 times as much as the inputtechnology .velocity. This output velocity satisfies the requirementsof taking the cartridge out. But in order to fulfill the .HU Sheng-hai , professor , was born insituation of the acceleration increasing rapidly , the1954 , China. He has publshed more thanforces of the driven cam are analyzed. And the results30 academic papers intermational journalsshow the force in the range of the driven cam deforma-and conference proceedings.His researchtion allowed.interests are : CAD/CAM etc.References :ZHANG Jia-tai ,professor , doctoral su-[ 1 ]LU0 Ani. Study on the technology and the simulation of ag-pervisor ,was born in Jiangsu , in 1943 ,ile sellfeeding system[ D ] Harbin : Harbin EngineeringChina. He has published more than 30University , 2003( in Chinese ).academic papers international and interna-[ 2 ]PU Langgui ,JI Minggang. Mechanism design[ M ] Beitional journals and conference proceed-jing : Higher Education Press 1998( in Chinese ).ings. His research interests are : computer[ 3 ]YIN Mingfu , CHU Jinkui ,ZHEN hong. Study on the one-integrated manufacturing system( CIMS ) , CAD/CAM etc.side machining principle and the new type of point contact ofthe globoldal cam mechanism[ A ] IFT0MM2003[ C ]Tianjin 2003.LIU He-ping was born in Heilongjiang ,[ 4 ]RUI Zhiyuan , CHENG Linzhang. Dynamic simulation ofin 1975 , China. He received the bache-virtual prototyping based on the combination between Pro/Elor' s degree in Mechanical Design fromand ADAMS[ J ] Modern Manufacture Engineering , 2005Jiamusi University in 1997 and M.S. de-( 1 ):56 -58( in Chinese).ree in Mechanical Design and Theory[5 ]LUO Ani. Simulation of five degree of freedom manipulatorrom Harbin Engineering University inusing Adam([ J ] Computer Simulation ,2005 ,22( 7 ) 2012003. He began to work as a Ph. D candidate in the School of- 204( in Chinese ).Mechanical and Eletrical Engineering in 2002 , in Harbin Engi-[ 6 JZHANG Jinping. The technology of virtual prototype and theneering University. His curent researches focus on the underwa-implement on ADAMS[ M ] Xi' an : Northwest Industry U-ter robot. His main research aspects : mechanical design andniversity Publishing House , 2002( in Chinese ).theory.中国煤化工MYHCNMHG.