Wang Yang, Cui Jinlei
Abstract: Based on the introduction of the working principle of the biomass flat-die molding machine and the analysis of the pressure roller movement, the reason of the sliding of the pressure roller is deduced and the design of the pressure roller is proposed. By analyzing the characteristics of the cone roller, Squeezing pressure should meet the conditions that the direct pressure roller sliding action can increase the compression stroke of biomass, is conducive to material molding.Conc roller mathematical model is conducive to the determination of the relative size of flat-die molding machine to improve its Performance and efficiency.The research provided theoretical support for the optimization design of flat-die forming machine in the future.
With the depletion of one-off energy such as oil and coal in the world, the problem of living environment pollution has become increasingly prominent, and energy, environmental protection and other issues have drawn intense attention. In recent years, the development of low-carbon, environment-friendly and sustainable economy has been It is imperative.
As a traditional agricultural country, China has abundant biomass resources.As of the end of 2010, the amount of surplus straw in rural areas reaches 7.26 × 109t, equivalent to 3 × 109t standard coal, minus industrial production, back to the field, pellet feed processing and living part of the burning, as well as 2.5 × 109t or so.Forest waste can reach 37 million hm per year2.
In order to avoid the waste of resources, to better protect the environment and to ease the energy crisis, biomass pelletized fuel has been widely used.Because of its simple structure, easy to manufacture, install and maintain, and low cost, It is widely used in small-scale production such as in rural areas and is widely used in small-scale production such as in rural areas.As the key equipment for producing pellet fuel, it is indispensable for the research, analysis and optimization of biomass forming machine.
1 biomass pellet molding machine the key structure and working principle
Biomass pellet fuel flat-die molding machine structure shown in Figure (1), by the motor, reducer (transmission), transmission spindle, material room, pressure roller, pressure roller frame, flat-plate, mold and other key components composition.
Normal work, the molding machine flat-plate fixed to the rack, the motor through the belt connected to the reducer pulley deceleration, so that the drive spindle to the appropriate speed; drive spindles will pass power to the pressure roller frame, driven pressure Because the production process is filled with biomass material between the pressure roller and the flat mold plate, during the rotation of the pressure roller bracket, the pressure roller and the material as well as the material and the flat platen generate friction force between the platen and the friction roller Under the action of autobiography, while continuing to squeeze the material into the mold.In the strong pressure roller and flat mold plate extrusion, the material is gradually compacted, and with the subsequent squeeze into the material pressure from the mold. After forming the pellet fuel to leave the die hole, the pellet is cut into a certain length by the cutter and then collected from the discharge opening.
For the production of biomass pellets of different diameters, according to the specific size to replace the corresponding die hole diameter of the flat-plate and forming molds.At the same time to better meet the production requirements, the flat-plate around the heating equipment should be equipped with timely adjustment of biomass Water content of raw materials, in order to ensure the production of flat-type molding machine requirements.
2 Biomass Particle Molding Machine Roller Characteristics
2.2 Pressure roller force characteristics Can be seen from Figure 3, in the actual production, the pressure roller and the flat-plate will ask a pure rolling circumference on the day line inside the roller relative speed faster, this advanced sliding called Sliding scroll; outside of the H line, the relative speed of the pressure roller is slow, this hysteresis slip is called slip rolling.
2.3 Mechanics Analysis of Extrusion of Biomass Material by Roller Figure 4 shows the mechanics analysis of extrusion of biomass material by the pressure roller. The stress analysis is performed at any point B of the extrusion material, and the material is applied by the pressure roller Squeeze pressure N 'and friction force F', the size of which is the same as that of the pressure roller, in the opposite direction.At the same time, in the production process, the flat mold plate gives the material a horizontal friction force Fx and a vertical support force Fy Too:
From (5) to (8), compared with the pure roll, roll slip, slip rolling is the original redistribution of forces, not only to force the horizontal direction of the material to increase, increase The preloading of the material, but also enhance the squeezing force in the vertical direction, making the biomass particle flat-die molding machine plate thickness thinner, far less than the thickness of the ring mold.Therefore, the direct pressure roller The resulting sliding effect is not entirely negative.
Due to the existence of slip rolling and sliding scroll rolling, which speeds up the pressure roller and flat mold plate wear speed.In order to save costs, the design process will be processed into a symmetrical flat die structure, both positive and negative; at the same time the pressure roller Shape re-design, change into tapered roller, the pressure roller in the width of the line speed, eliminating the sliding wear.
Improvement Design and Characteristic Analysis of Biomass Pellet Forming Machine
4 Conclusion
Through the working principle of the biomass pellet fuel flat-die molding machine and the analysis of the characteristics of the pressure roller (stress analysis of the roller and extrusion mechanics analysis of the biomass) Motion analysis, as well as the improvement of design and dynamic analysis, learned cone roller can significantly improve the performance of the existing flat-die machine, reduce the pressure roller and flat-panel wear and tear, greatly improving their life expectancy and effectiveness.
(1) As the pressure roller and biomass to produce sliding, resulting in friction between the shear effect of the two, the crude fiber content of larger materials can be better rubbing, compression molding, which greatly improves the quality of molded products .
(2) Due to the introduction of sliding rolling zone and sliding rolling zone, the conical roller increases the compression stroke of the material in the vertical and horizontal directions, greatly reducing the thickness of the flat-plate and saving manufacturing and processing costs.
(3) Neglecting the influence of the static friction and the rolling friction resistance moment between the pressure roller and the flat mold plate, when 0 satisfies the formula (16) and the formula (18), the cone roller at this time produces the maximum pressing force For different parameters of the cone roll forming machine provides a design theory, in order to better optimize the design.
