可調軸心距之滾子從動件搖擺式共軛凸輪的設計

The Design of Conjugate Disk Cam Mechanisms with an Oscillating Roller Follower Whose Fixed Pivot Being Adjustable

黃子綺(Tzu-Chi Huang)

指導教授 ： 吳隆庸

國立清華大學/工學院/動力機械工程學系/碩士(2017年)

摘要

共軛凸輪機構是一種利用凸輪同時與從動件保持兩個以上的接觸點，以達到從動件確動效果的機構類型。實際應用時，凸輪與從動件間可能存在著間隙。然而間隙將導致從動件撞擊凸輪表面，進而產生噪音與降低機構精度。為了避免共軛凸輪機構產生這種現象，本論文探討如何藉由調整凸輪與從搖擺式滾子動件間的中心距離來施加預壓，藉此消除凸輪與從動件間的間隙。
首先，利用速度瞬心的概念，計算調整軸心距離前後的凸輪輪廓。接著，以調整完軸心距離後的凸輪輪廓為基準，計算接觸點法線方向的輪廓變異量。最後，根據赫茲接觸應力的相關理論，計算調整軸心距前後接觸點的預壓力、接觸力與最大接觸應力。
本研究的結果指出，藉由調整軸心距產生的預壓力可有效消除凸輪與從動件間的間隙。假設僅凸輪與從動件滾子接觸點不為剛體的狀況下，當凸輪與滾子的材料皆為AISI 1045 鋼 冷拉且凸輪角速度為1200 rpm時，軸心距的調整量應落在-5 μm以內，以避免施加過大的預壓力導致材料的破壞。

關鍵字

滾子 ； 搖擺式共軛凸輪機構 ； 預壓 ； 赫茲接觸應力

並列摘要

Conjugate cam mechanisms are one of cam mechanisms, with two different cams contact with the follower in two or more than point simultaneously, keeping the follower positive. Generally, there might be the clearance between the cam and the follower. However, it can cause the follower to impact the cam, generate the noise and decrease the precision of the mechanism. In order to avoid this situation for the conjugate cam mechanisms, this work researches how to adjust the distance from cam center to the follower pivot to create preload and eliminate the clearance between the cam and roller follower.
First, based on the concepts of the velocity instant centers, calculating the cam profiles in different distances from the cam center to the follower pivot. Next, in the principle of taking the original cam profile as the standard profile, calculating the variation of the contact point between the cam and roller in the direction of the normal line of the contact point. Finally, from the concepts of the Hertz contact theory, calculating the force of the preload, the contact force and the maximum contact stress in different distances between the two rotation centers.
According to the researching result, the force of preload, created after adjusting the distance from the cam center to the follower pivot point, can eliminate the clearance between the cam and the roller effectively. In the assumption that only the contact point between the conjugate cam and roller follower is not rigid body, avoiding the material damage caused by the excessive force of preload, as the material of the cam and roller follower is AISI 1045 steel cold drawn and the angular velocity of the cam is 1200 rpm, the appropriate adjustment distance between two rotation centers should be less than .

並列關鍵字

roller ； conjugate oscillating cam mechanism ； preload ； Hertz contact stress

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