【摘要】：在冶金、煤礦、礦山、水泥等行業(yè)大量使用各種振動篩分設備,而篩板是保證振動篩能否正常使用的關鍵配件之一。棒條篩板是近幾年出現(xiàn)的一種新型篩板,這種篩板使用彈簧鋼作為主要部件�，F(xiàn)有結構如下：彈簧鋼棒條一端穿入預先打有安裝孔的方形空心鋼內,用壓條壓緊固定,另一端為自由懸空狀態(tài),可以自由振動。這種篩板在實際生產中存在兩個主要問題：篩板制作過程中先在角鐵上鉆孔,再把角鐵焊到一起,這樣可能造成篩板上的兩個孔不在一條直線上,對于穿棒條造成一定困難；或是導致安裝不便,或是導致安裝固定不可靠,造成篩板在工作過程中出現(xiàn)松動斷裂等意外情況。 本文研究一種新型振動篩用焊接棒條篩板,這種篩板是把尺寸一定的彈簧鋼棒條按照有關尺寸要求直接焊在鋼板上,從而解決前述的棒條穿孔安裝工藝的問題。棒條需要具有高的屈服強度和疲勞極限以保證篩板的耐磨性能和抗疲勞斷裂能力,而篩板框架性能要求韌性和焊接性良好。因此棒條材料選彈簧鋼,篩板框架材料選普通碳素結構鋼。這兩種材料之間的焊接屬于異種鋼之間的焊接,由于異種鋼的化學成分和物理性能等存在較大的差異,使其之間的焊接較為困難,如果工藝控制不好,會增加焊縫及熱影響區(qū)的淬硬程度,降低焊接接頭的抗裂性；焊接區(qū)域和被焊工件溫度差增大,使焊接應力增加、焊接應變速率增大,導致焊接裂紋更容易產生；會使焊縫和熱影響區(qū)中的氫不易逸出,使裂紋產生的概率增大。本文通過研究65Mn、60Si2Mn、60Si2CrV三種彈簧鋼棒條與Q235鋼板的焊前預熱和焊后熱處理工藝,來改善焊接接頭的性能。主要內容包括：根據(jù)母材成分確定焊條成分；焊接前母材進行200℃、300℃、400℃的預熱,預熱時間為30min；焊接后立即在200℃、250℃、300℃、350℃、400℃、450℃回火,回火時間為2h。利用金相顯微鏡觀察每個試樣的顯微組織結構,分析不同工藝下組織的變化；洛氏硬度機測定每組試樣的焊縫不同區(qū)域的硬度,疲勞試驗機測定不同工藝下篩板棒條的使用壽命,通過組織、硬度、疲勞壽命綜合分析材料組織對性能的影響,得出最佳的熱處理工藝。 試驗結果：用于焊接彈簧鋼和碳素結構鋼的焊絲選用結506低氫鉀型焊絲；用三種彈簧鋼焊接篩板是最佳預熱溫度為300℃,保溫時間為30min,回火溫度為450℃,保溫時間為2h。 為了滿足實際生產和經濟性要求,對比三種材料。發(fā)現(xiàn)65Mn彈簧鋼制成的篩板疲勞壽命最短,60Si2Mn制成的棒條篩板次之,60Si2CrV制成的篩板最好。但從經濟性和實用性能兩方面考慮,60Si2Mn制成的篩板成本較低,但能滿足生產要求。 采用最佳焊接工藝,把用60Si2Mn制成的篩板應用到礦山機械上,與原結構的篩板使用壽命近似,都在三個月以上。
[Abstract]:A variety of vibration screening equipment is widely used in metallurgy, coal mine, cement and other industries, and screen plate is one of the key accessories to ensure the normal use of vibrating screen. Bar screen plate is a new type of screen plate which appears in recent years. Spring steel is used as the main component of this kind of screen plate. The existing structure is as follows: one end of the spring bar is pierced into the square hollow steel with pre-installed holes, and the other end is freely suspended, which can vibrate freely. There are two main problems in the actual production of this kind of screen plate: first, the angle iron is drilled in the process of screen plate making, and then the angle iron is welded together, which may cause the two holes in the screen plate not in a straight line, which may cause some difficulties for piercing the rod bar, or lead to the inconvenience of installation, or the unreliable installation of the screen plate, resulting in loosening and fracture of the screen plate in the course of work. In this paper, a new type of welded bar screen plate for vibrating screen is studied. The screen plate is to weld the spring steel bar with a certain size directly on the steel plate according to the relevant size requirements, so as to solve the problem of the above mentioned rod and bar piercing installation process. The bar needs high yield strength and fatigue limit to ensure the wear resistance and fatigue fracture resistance of the screen plate, while the frame performance of the screen plate requires good toughness and weldability. Therefore, the rod material is spring steel and the screen plate frame material is common carbon structure steel. The welding between the two materials belongs to the welding between dissimilar steel. Because of the great difference in chemical composition and physical properties of dissimilar steel, the welding between dissimilar steel is more difficult. If the process control is not good, the hardening degree of weld and heat affected zone will be increased, and the crack resistance of welded joint will be reduced. With the increase of the temperature difference between the welding area and the welded workpiece, the welding stress and the welding strain rate are increased, which leads to the welding crack is easier to occur, and the hydrogen in the weld and heat affected zone is not easy to escape and the probability of crack is increased. In this paper, the preheating and post-weld heat treatment processes of 65mn, 60Si2Mnand 60Si2CrV spring steel bars and Q235 steel plates are studied to improve the properties of welded joints. The main contents include: determining the composition of electrode according to the composition of base metal; preheating the base metal at 200 鈩，

本文編號：2509171