1、Multi-object optimization design for differential and gradingtoothed roll crusher using a genetic algorithmAbstract: Our differential and grading toothed roll crusher blends the advantages of a toothed roll crusher and a jaw crusher and possesses characteristics of great crushing, high breaking effi
2、ciency, multi-sieving and has, for the moment, made up for the shortcomings of the toothed roll crusher. The moving jaw of the crusher is a crank-rocker mechanism. For optimizing the dynamic performance and improving the cracking capability of the crusher, a mathematical model was established to opt
3、imize the transmission angle and to minimize the travel characteristic value m of the moving jaw. Genetic algorithm is used to optimize the crusher crank-rocker mechanism for multi-object design and an optimum result is obtained. According to the implementation, it is shown that the performance of t
4、he crusher and the cracking capability of the moving jaw have been improved.Key words: differential and grading toothed roll crusher; crank-rocker mechanism; genetic algorithm; multi-object optimization1 IntroductionMaterial crushing is an indispensable process for production in many industries (e.g
5、. mining, metallurgy,chemical industry). Traditional crushers (e.g.,jaw crusher, impact hammer crusher, rotary crusher and hammer mill) mainly depend on the working parts that put the impact pressure on the materiel to be crushed in order to implement crushing. Crushers are of unwieldiness, low effi
6、ciency and high energy consumption. These disadvantages have greatly restricted efforts to improve their crushing capability.The traditional crushers we already have cannot meet the current needs of production. In recent years, a number of British MMD toothed roll crushers have been used. But from c
7、asual investigation, we find some shortcomings in these toothed roll crushers: 1)Material crushing is realized by meshing teeth. All the raw minerals to be crushed are sent into a crushing chamber and discharged by force through the meshing teeth including those up to the standard of particulates. T
8、he crushers, failing to accomplish real grading crushing, using up a lot of energy, are inefficient and the crushing teeth quickly show damage from metal fatigue. 2) The phenomenon of jam occurs under two conditions. One is a high flow in which large chunks of coal are mixed with small pieces. The o
9、ther one is high humidity in which teeth become clogged with wet coal. Because the toothed roll crusher has no effective grading mechanism, the result is unsatisfactory and we cannot depend solely on the overworked meshing teeth. According to investigations in a number of coal mines using MMD toothe
10、d roll crushers, we found that none of them could even reach the nominal amount of crushed material.3) The crushing capability of MMD crushers isimproved by increasing the power and strength of transmission parts, resulting in high power consumption and costs. Based on these considerations, combined
11、 with the demand of the China Shenhua Energy Co., Ltd. and the Shendong Coal Branch, our research team designed a new, highly efficient differential and grading toothed roll crusher to make up the lacks from traditional crushers.As Fig. 1 shows, the crusher breaking part is composed of differential
12、teeth and a crank-rocker mechanism.A sketch of the moving jaw crank-rocker mechanism is shown in Fig. 2. In a search for optimization designs of a crank-rocker mechanism, itseems that much of the literature consulted aims only at optimizing the transmission angle . For example,Li, et al just opted f
13、or minimizing the travel characteristicvalue of the moving jaw m of the jaw crusher. But in a practical and typical crushing process, the capability of the moving jaw is closely related to both the transmission angle and the travel characteristic value of the moving jaw. We have used a GA (genetic a
14、lgorithm) in order to optimize the crank-rocker mechanism of the differential and grading toothed roll crusher for the purpose of optimizing the transmission angle and minimizing the travel characteristic value of the moving jaw m.2 Kinetic analysis of the crank-rocker mechanismThe performance of a
15、hinged four-bar mechanism depends on the relative length of its bars. If we set the length of the rocker c equal to 1, then the relative lengths of the crank, the connecting rod and the body frame are a, b and d. The mathematical model of the design of the crank-rocker mechanism is independent of th
16、e actual length, which makes it more universal.2.1 Optimal transmission angle The transmission force of the crank-rocker mechanism depends mainly on the transmission angle . The bigger the transmission angle, the better the transmissionforce property it has. The transmission angle changes during the process of transmission. The choice of a suitable size for each component can optimize the minimum transmission angle. Therefore, it is necessary to increase th
