Study On The Application Of Spur Gear Precision Forming With The Approach Of "Half Swelling-up And Half Grooving"

This paper studied the application of precision forming spur gear with theapproach of “half swelling-up and half grooving” proposed by my tutor, aiming at thereverse idler gear from Tianjin Tianhai Precision Forging Company Limited, afteranalyzing and summarizing the main precision forming methods. The formingprocess of approach was like that: firstly, realizing the preliminary shape with propergear flange height by the billets. The workpiece should have different radialdimension and shape of the two ends, and the cylindrical surface should rise and fallto the average diameter like half-long ridge; secondly, pushing the workpiece throughthe die with clink for the tooth socket and realizing the final shape of the tooth andtooth socket of gears. During the splitting extrusion final forming, the tooth rised andthe tooth socket was deepened. The actual manufacturing process was determined tobe： blanking�'heating�'preforming�'trimming and piercing�'final forming�'cleaning�'finishing.The concrete steps of the new precision forming approach have been refined,especially that open die forging was taken for the preform sequence.Considering the conditions of production equipments in the company, four setsof moulds for the new approach, including the open die forging performing mouldused on the10MN screw press, trimming and piercing die used on the1000kNmechanical press, the splitting extrusion final forming mould used on the6.3MNcrew press, and the forming die used on the5000kN hydraulic press.There was an actions of horizontally locating up, moving down smoothly,stopping down stably, and resetting quickly in the step of the splitting extrusion finalforming, and the action could not be realized by the now available mechanism usedon the forging equipment. The stable mechanism with chain drive, weight balanceand stable displacement of the pendulum was designed to realize the actions.The former three moulds were manufactured and put into try-production withlead billets and steel billets by Tianhai company. The try-production was mostlysuccessful, and we finally got the expected steel workpiece after precision forming. Aiming at the problem met during the try-production with steel billets, that thescrap in the splitting extrusion final forming sticked firmly to the bottom die afterseperated from the workpiece, the treatment scheme of making the crap to be burr,which would be taken away by the workpiece, was proposed. However for the urgentproduction schedule, the industrialization of reverse idler gear precision forming wasnot realized. So the problems such as working life of the designed mould couldn’t besay for sure.For the first time, the precision forming of a kind of spur gear with plenty oftooth-numbers and modulus was realized based on the theory of “half swelling-up andhalf grooving”. The study verified the feasibility and the practicability of the newapproach, and had a deep influence on promoting the industrialization of reverse idlergear precision forming.