The process analysis and improvement of the slender and flat shaft of track recorder

Joumnal of Marine Science and Application, Vol.5 ,No.2 ,June 2006,pp. 47 -50The process analysis and improvement of theslender and flat shaft of track recorderDAI Tong-yan'，WANG Wei? , and LIU Ying31. Department of Automobile Engineering, Heilongjiang Institute of Technology，Harbin 150050, China;2. Equipment Department, CPENE, Jilin 132002 , China;3. Department of Mechanical and Electrical Engineering , Heilongjiang Institute of Technology, Harbin 150050, ChinaAbstract: A slender and flat shaft is a key part of the track recorder in marine vessels. However, theaxial straightness of the shaft often exceeds standard measurements afer it is machined. It has also beenfound that is precision does not last a long time. After thorough analysis of these problems the mainreasons that affect machining quality are identified-and a process modification plan is put forward thatmeets design requirements of the shaft. The production and practice indicate that the precision of theshaft is stable for a long period and the quality of products improved subtantially after new measureswere employed, securing the e accuracy of the track recording of the marine vessel,Keywords: slender and flat shaft; intemal stress ; straightnessCLC number: TH132 Document code:A Article ID:1671 - 9433(2006)02 - 0047 -041 Introductiontion part of the track recorder, which is 1 145 mm inlength and 16 mm in maximum diameter. The length-The track recorder is an important technical instru-diameter ratio of the shaft is 71. 5, which results inments produced for a marine ship. It is used for real-poor rigidity, with the axial straightness requirement oftime drawing of a ship's course. The control system ofthe part is strict ( the axial straightness tolerance isthe track recorder is an open loop system driven by a0. 05 mm). Furthermore, the cross section of the shaftstep-by-step motor, so the precision of the transforma-is oblate. These aspects indicate how challenging it istion part directly affects the accuracy of the track re-to machine a slender and flat shaft. Design require-cording. A slender and flat shaft is the key transforma-ments of the shaft are shown in Fig. 1.rEoa.o]128叫D分@1108士0. 13中国煤化工Fig. 1 Drawing of the slender.MYHCNMHGWhen machining the shaft in a factory, it was foundthat the axial straightness of the shaft could not consist-Received data:2006 -01 - 13..48●.Jounal of Marine Science and Aplication , Vol.5 ,No.2, June 2006ently meet design requirements. Even when the shaft2) The deformation increases during heat treatment duewas precise enough when manufactured, its precisionto the unreasonable supports.did not last for a long period. Hence, the manufactureBecause the equipment is limited, the heat treatment isand use of the track recorder was seriously affected.For this reason, thorough analysiswas performed on theprocessed in chamber electric furace. The shaft ismain reasons affecting the machining quality, and asupported on the channel bar. The bending deforma-tion of shaft is kept because the channel bar has largetechnology improvement plan was identified. This newtechnology resulted in a shaft with straightness thatdeformation itself and the high temperature creeps. Inmeets design requirements and ensures the good assem-original process ，although the bending deformation isbly precision and performance of the whole recorder.eliminated by a cold alignment, the internal stress in-creases. The straightness error of the shaft is calculatedThrough test producing and periodical rechecking forone year, it is found that the once checking qualifica-as fllows's):tion ratio of the shaft increases from 30% to 100%.If the channel bar is bent downward, which can be re-garded because the bar is hinged at two ends, and the2 Original process and analysisdeformation is shown in Fig. 2, the maximum deforma-tion“Y.”is at the midpoint.The original design for the shaft used 45 steel. Theq=15 N/mprocess is as follows :Blanking-→quenching and high temperature tempering→cold alignment- →rough turning outer diameter-→coldalignment - +semi finish turming, finish turming outer di-ameter and shaft necks- +cold alignment- →rough grind-= 145 mming shaft necks, rough grinding surfaces- +finish grind-ing shaft necks, finish grinding surfaces.Fig.2 Delection of two-end hinged shaftTo achieve the requirements of the machining preci-q=l5 Nmsion, problems related to the above process were iden-tifed:1 )The tempering treatment is made once after blanking1=575 mmc=565 mm .in original process, so there is no heat treatment to re-move internal stress during the later machiningFig. 3 Deflection of two-point hinged shaft with overhangprocess. For this reason, it is difficult to remove inter-nal stress which is produced by machining, and thed=16mm,l=1145mm,thenq=15N/m,J=shaft will generate bending deformation.0.322 x 10* mm, ThenOriginally, cold alignments are arranged after rough5ql4turming and finishing turning respectively, which cre-1.= 384EJ=ates reverse bending to counteract original deformation.5x15 x(1145 x 10-3)*After cold alignments, the bending deformation decrea-384 x200x109 x0.322 x10* x(10-3)4= -0.52 mmses but the internal organization is unstable. If it is ma-中国煤化工Ifthwhich can be regar-chined or stored for a period, the part will release re-dedMHc N M H Gis hinged beam withsidual intermal stress and produce new bending deform-overhang of length c. The maximum deformation“Y。”ation.[1]21. This is the main reason for straightnessis at the end of overhang, shown in Fig. 3.exceeding standard requirements.DAI Tong-yan ,et al: The process analysis and improrement of the slender and flat shaft of track recorder. 49.Y.= 24E[P -6l2 -3e']=. In the machining process， annealing was arrangedthree times to remove residual stress. High temperature15 x565 x10 -3aging after semi-turning(t = 500 ~ 550C, for4~6h),24 x200x 10° x0.322x10* x(10-3)*low temperature aging after finish turming and rough[(575x10-3)*-6x575x10-3 x(565x10-3)2-grinding(t=240C, for 12h).3x(565x10-3)3]= -0.2 mm3.4 Frequently turning over and repeatedly grinding3) The stability of metallurgical strueture of the shaft isduring surface grinding to reduce heat stressrelatively weak, which has serious influence on intermalstress and deformation. With changing of the metallur-Since surface grinding heats the work piece on onegical structure , the specific volume is changed, so theside, it is easy to produce heat stress. The new processinternal stress and deformation are created.specifies that the machining surface must be turned 0-ver after grinding off 0. 05mm. The grinding depth isless than 0. 01 mm. Then bending deformation due to3 Improving measurementsheat stress wwas reduced to minimum.3.1 New material to reduce structure stress(4[5]3.5 Reasonable supports are set up during heatA new material, T10A, was selected as more suitabletreatments and machining procedurefor the shaft than 45 steel. It was found that the origi-Through theoretical analysis and dimensional optimiza-nal coarse lamellar pearlite should be changed to gran-tion“， the supporting method during heat treatmentsular pearlite after spheroidizing tempering. The granu-and machining was developed as shown in Fig. 4. Inlar pearlite' s free energy is the lowest at normal tem-this case， the bending deformation caused by dead-perature and the organization is more stable than coarseweight was decreased as minimally as possible.lamellar pearlite. The organization stress was reduced.The modulous cementites were evenly arranged on softg=l5 N/m .ferrites and the wearability of the wearing surface wasgrealy improved.3.2 Cold alignments are not permitted during thewhole process to reduce deformation stress1-629 mm-258叫Cold alignments are the main reason for the shaft' sFig.4 Optimized suporting methodstraightness exceeding standards, so they were not per-mitted in the new process. Through enlarging the rawmaterial' s diameter and length, the central hole wasY.=24ej[P -(6l-3c)e2]=redrilled after every machining and heat treatment, and15 x258 x10 -3uneven allowance was cut to modify original straight-24 x200x10% x0.322 x10*x(10-3)4xness error.[(629x10-3)-(6x629 -3x258) x10-3 x(258x10-)2]= -0. 012 mm3.3 Arrange heat treatment procedure properly toeliminate residual stress inside the partY=q[6e2 -部门=Pre-heat treatment applied spheroidization annealing to中国煤化工<(10-)4xeliminate residual stress during rlling and make the[CNMHGorganization stable and improve wearability and ma-[ox(258XIU广-一x(029x10-3)2]=chinability.-0.009mm●50.Journal of Marine Science and Aplication, Vol.5 ,No.2, June 2006The calculating results indicate that the maximum de[2] CHEN Lide, U Xiaohui. Mechanical manufacture technol-formation at the midpoint is only 0. 009mm, 1/58 ofogy[M]. Shanghai: Shanghai Jiao Tong University Press,2004.that in the two-end hinged case. The maximum deform-ation at end point is only 0. 012mm, 1/16 of that in[3] XUN Wenxuan. Mechanics of Materials[ M]. Beijing: Sei-ence Press, 2005.the two-end hinged bar with overhang. The support[4] HU Guangli, XIE Xiwen. Heat treatments principle andrackets were designed according to this calculated re-technology of steel[ M]. Xi' an: Northwesterm Polytechni-cal University Press , 2004.Practice showed that the slender and shaft in track re-[5]QI Baosen, LI Li, LV Jing. Mechanical Engineering Mate-rials[ M]. Habin: Harbin Institute of Technology Press,corder reached the design requirements and the quality2003.notably improved after taking some new measures.[6] SUN Jingmin. Modemn mechanical design method[ M ].Harbin: Harbin Institute of Technology Press, 2003.4 ConclusionsDAI Tong-yan, borm in 1968, is an as-Recommendations for a slender and flat track recordersociate professor. She received a B. S.shaft in a marine vessels follows:from Harbin Shipbuilding Engineering In-stitute in 1990. Later, she earned an M.1) The key point is to reduce the internal stress to im-s. from Harbin Engineering University inprove the straightness of the slender shaft, and it is2003. Since 1990, she has taught andparticularly important that cold alignments are not per-performed research in mechanical engineering materials and me-mitted during machining in order to prevent the formingchanical manufacture technologyat Heilongjiang Intitute ofTechnology.of unstable residual stress inside the part.2) Stable metallurgical structure should be selected to .WANG Wei was borm in 1968， andgraduated in 1990 from the Department ofreduce structural stress. A series of heat treatmentMechanical Technology， Harbin Ship-processes to remove residual stress inside the part to abuilding Engineering Institute. She workslowest limit are effective measures to keep the axialin the CPENE equipment department as astraightness.senior engineer.3) Designing reasonable grinding process to reducegrinding deformation and applying the best supportingLIU Ying was borm in 1974. She receivedmethod to make the deformation minimum have speciala B. S. from Jiangsu University in 1997.action on reducing the straightness error during the heatSince then, she has been working at Hei-treatments and machining operation.longjiang Institute of Technology as ateacher. in 2006 she earned an M. S.from Harbin Engineering University.References:[1] FENG Jingwen. Mechanical manufacture technology princi-ple[ M]. Beijing: Tsinghua University Press , 2002.中国煤化工MYHCNMHG