Gypsum Wallboard Extruder Screw Mechanical Properties And Its Parameter Optimization Study

Traditional gypsum wallboard production method which used mold shape is difficult to achieve automation, as well as the continuous extrusion molding which is easy to automate the assembly line production is the direction of the development of gypsum wallboard manufacturing in the future. The mechanical properities of the screw and it's frame parameter is the key to ensure the quality of gypsum wallboard and productivity. In this paper, we study on the mechanical properties and the frame parameters of the screw which is the core components of gypsum wallboard screw extruder .The main work done as follows:1,Adopt the solid cypriot conveying theory which is used in single screw extrusion, analysis of the load on the feed paraph and the compression paragraph, get the pressure distribution on the push side of the spiral body.2,Adopt a mixed penalty function methods optimizes the spiral angle,the screw's trough,the screw's deep and the screw'staper, in order to reduce the axial force and torque when the screw works. The optimized result shows that when the materials'pressure of extrusion is fixed, the axial force and torque of the working screw will be the smallest,if the spiral angle is 14.3⁰, the screw's trough is 63mm, the screw's deep is H₁=23mm,H₂=10mm and the screw's taper is 1. 63⁰.3,Establishing a geometric parameters model for the spiral body, application of analysis software ANSYS makes a mechanical finite element stress analysis for the spiral body , the results of the analysis indicate that the symmetric curve shape section is one kind of more reasonable section . The increase of the spiral body's trapezoid angle and the spiral body cross-section's bottom trough can reduce the stress of the the spiral body .The minish of the spiral body cross-section's top trough and the height can reduce the stress of the spiral body too. When the spiral body's trapezoid angle value select between 15°and 27°, can make the spiral body have a smaller stress at the same time, the transmission efficiency of the screw will not reduce too much. 4. According to the influence on the stress of the spiral body when the size of the section and the trapezoid angle changed, we optimize the symmetric curve shape section of the spiral body, contrast to the trapezoidal cross-section, both have the same size of a,b,c ,make the the spiral body's stress value reduced, at the same time, make the screw's feeding efficiency increased 25.8%.5,Experiments check the pressure on the push side of the spiral body, prove the validity of the theoretical calculation. Experiments check the cross-section's pressure of the screw group, the cross-section perpendicularity to the aix of the screw, prove the validity of the analyse result of the stabilization of the extrude pressure of the screw group. Under different rotational speed,different materials the extrude pressure of the screw group were measured.