Attrition Expiration Analysis of Circular Mould and the Research on Abrasive Wear of 45~# Steel by Alfalfa Powder
|School||Gansu Agricultural University|
|Course||Agricultural Mechanization Engineering|
|Keywords||circular mold expiration alfalfa powder soft grinding abrasion wear resistant|
The attrition of the material is the common expiration form in the mechanical product, and brings the huge economic loss to the society every year. Using the circular mold Pelletier producing the mixed feed to product the alfalfa grass pellet in our country, as the main expiration form on product and utilize the alfalfa forage product, which has solved the problem of stores, transports and feeds on the process of the alfalfa industrialization. But in production practice of using the Pelletier of the mixed feed to product the alfalfa grass pellet, the attrition of circular mold is extremely serious, that is to say the abrasive resistance of circular mold is low in wearing alfalfa grass pellet, its output only about 1/4 of that of the mixed feed, and increases the production cost of grass pellet because the alfalfa’s physical and mechanical property is different from the ordinary feed. The material of the circular mold Pelletier machine mostly takes the high quality alloy steel as the raw material, its cost is expensive, and which increases the cost of enterprise’s product in some way. Using the high quality carbon structural steel 45# steel which low in price as the circular mold’s representative material and the reference material with alfalfa grass powder in attrition performance, which is the foundation work for the later anti-alfalfa metallic material’s attrition. Therefore, analyzing the expiration reason of circular mold, studying the influence of the alfalfa grass powder’s wear performance with the metal material, which have the practical significance to enhances the circular mold’s service life.This topic’s prime task has the following several aspects,①Analyzes circular mold expiration form, observe the actual circular mold expiration mechanism from macroscopic, and further analyzes its expiration reason from the attrition appearance;②Carries on the chemical examination of the 45# steel’s raw materials, determined that its raw materials itself does not have the flaw;③Carries on quenching processing using the designated heat treatment plan, firstly makes the micro-structure homogenizing preheating processing for four group of test sample, causes its grain refining, and the micro-structure to be unified, next makes the conventional quenching heat treatment and the subcritical quenches heat treatment for four groups of test samples according to the predetermined plan and tempering ,and then obtains various test samples degree of hardness value;④Performs the impact test to the test sample, obtains its average tenacity value;⑤Carries on the grinding abrasion weightlessness experiment, mainly observes the wear resistant situation whether good or bad from the mass defect, with the scanning electronic microscope to observe the wearing surface’s macroscopic wear condition, to judge the abrasion mechanism, and analyzes and explains the reason of wear resistant again using the micro-structure microscope from the microstructure aspect, further confirms the test result. Finally obtains the experimental conclusion, the conclusion is as follows:(1) Because the circular mold is wore, and causes the aperture is increased, feeding bevel edge is worn, the endophragm of model hole is uneven, and the inside diameter is increased, wall thickness reduces .those 4 kinds of structure expiration phenomenon caused the granulation stress relations changed and finally causes the circular mold expiration;(2) The plastic deformation and micro cuts produce the circular mold surface superficial material is drained under two kind of attrition mechanisms function , finally creates the circular mold’s attrition expiration.(3) The test sample’s wear resistance of quenched 45# steel to alfalfa grass powder is better than that of unquenched, what the wear resistance is best is the subcritical quenches heat treatment test sample;(4)The surface attrition of the alfalfa grass powder grinding compound to metal material—45# steel are the result of the hard and soft abrasive simultaneously, under the condition of hard abrasive, the wear is mainly the micro-cutting wearing, while it is dominated by the plastic deformation many times and the low cycle fatigue wear in the case of soft abrasive. When the test sample were quenched, the wear is mainly the micro-cutting wearing either, the plastic deformation weary which is the grass powder grinding medium to 45 # steel is not obvious. (5) In the abrasive attrition experiment of the alfalfa grass powder grinding to the 45# steel, sole enhances hardness is not the effective way of enhancing the wear resistant, the reasonable coordination of hardness, the plasticity and toughness can improve the attrition ability of 45 # steel to resistance alfalfa grass powder.