- 學位論文
模內直接加熱金屬成形之可行性研究
The Research of Direct Hearing Raw Material within the Forming Dies
摘要
現今社會所需求金屬製品往輕量化並提升強度方面發展，面對強度較高材料鍛壓所需成型負荷需求提升，目前相關加熱鍛壓成形方面有以下幾種；(1)加溫爐內胚料加熱後鍛造(2)電磁線圈感應加熱(3)電熱棒加熱模具以上方式均可加熱，但因加熱過程後才鍛造成形，導致部份會降低溫度而改變了材料應力大小。電阻式模內直接加熱胚料及恆溫鍛造製程，除了可降低材料溫度不均、表面氧化及表面材料晶粒粗化外，更可減少鍛造製程中因材料溫度降低而造成的應力大幅提升的因素，大大增加難加工成形合金材料的可鍛性及量產性。同時，鍛件材料是決定鍛造製程及模擬參數設定的關鍵因素。 有鑑於此，在本研究中提出一種可於成形過程中模內直接加熱胚料的鍛造方式，研究要點共分為以下四部份：(1)電阻式加熱機台製作；(2)電阻式模內加熱實驗；(3)差溫成形齒狀構件及(4)軟模成形齒狀構件，並利用有限元素軟體DEFORM-2D對模內直接加熱胚料進行差溫電阻加熱與齒型成形的模擬分析，電阻式模內加熱研究方面為探討模具在不同材料電阻率下、模具幾何形狀及胚料材料電阻等條件下，其溫度分佈與變化之情形，接著進行差溫齒形之鍛造成形，胚料採用難成形材料鍛造，在不同幾何形狀與模具材料的條件下加熱鍛造之情形。 經由實驗結果顯示，透過模內電阻式加熱胚料可在5秒內達到1000℃的成形溫度；同時模具及胚料幾何形狀不同會造成加熱位置的差異；當同體積材料截面積大小長度改變會導致加熱源的位置；當工件接觸面積範圍變小時，瞬間加熱溫升速率會加快。本研究利用開發之電阻式模內直接加熱胚料及成形製程，成功運用在胚料差溫鍛造成形及軟模具鍛打胚料成形。
並列摘要
Today's society requires metal products that are lighter and tougher, and the requirements on press forging of tougher materials becomes more rigorous. The following three types of heat press forging - furnace billet heated and then forged, heated by electromagnetic coil induction, and heated by electric heating rod die, all require heating before forging, and the consequent partial temperature drop can change the material stress. Meanwhile, a direct resistive heating of billets inside the mold, along with a thermostatic forging process, not only reduces the uneven distribution of material temperature, surface oxidation and surface material coarsening, but also alleviates the stress hike resulted from the material temperature drop during the forging process, thus greatly enhances the malleability and mass production capacity of alloy materials that are supposedly difficult to shape. Another point to mention is that the material is a key factor to the forging process and simulation parameters. In view of this, this research proposes a forging approach that directly heats billets inside a mold during the forging process. The study comes in four parts: (1) making a resistive heating machine; (2) experiment of the direct resistive heating inside a mold; (3) differential temperature forming dentate components; and (4) flexible die forming dentate components. The finite element software DEFORM-2D is used to simulate the direct heating of billets inside the mold and analyze the effects of the differential temperature resistive heating and dentation shaping. The study of resistive heating inside the mold looks into the temperature distribution and variation of the mold under various conditions with material resistivity, mold geometric forms and billet resistivity. Then, it's the study of forging differential temperature dentation, where the billets difficult to form are taken for heat forging under various geometric shapes and molding materials. The experiment shows that the resistive heating of billets inside the mold can reach the 1000℃ forging temperature within 5 seconds, and the mold and billet geometric shapes do not change the heating position; the size of cross-sectional area of the material can affect the heating source, i.e. when the contact area of a workpiece becomes smaller, the instant heating velocity will rise. By way of the development of a direct resistive heating and forging of billets inside the mold, this research has successfully made the billet differential temperature forging and flexible mold forging.