ObjectiveThe foldable bed is an important technology of the small apartment to realize the dual-use function. The selection of gas spring is mainly based on " wrong-trial”, which is lacking theoretical support and practical guidance. In order to shorten the production cycle and improve product reliability, it is especially important to conduct a theory research.

MethodIn this study, the foldable bed was taken as the research object, and its limit working conditions were set according to the actual working conditions. Based on statics and torque balance principle in theoretical mechanics, combined with the gas spring motion characteristic curve and its technical standards, the force analysis of the foldable bed and its gas spring was conducted under the limit working conditions of the foldable bed to complete the selection of the gas spring. The optimal install location of the gas spring on the bed was obtained using two intersecting circles. The force analysis of the bed at random foldable angles was analyzed and its motion curve was simulated via CAD-aided measuring tools.

Result This study set up the analysis and calculation theory of the gas spring of the foldable bed. Starting with two limit states of the use and storage, the theory to obtain minimum extension force, stroke and installation position of the gas spring was established; furthermore, the foldable bed at random foldable angle was analyzed and calculated. The motion law and the analysis method of the hover angle were obtained. This study took the common bed size (900 mm wide, 1 900 mm long) , 300 mm depth as an example, the minimum extension force, the stroke, the elastic coefficient, and the range of hover scope of the gas spring were 428 N, 190 mm, 1.06, and 18°−24°.

Conclusion The analytical methods and results constructed in this study can provide theoretical support and practical guidance for the design, selection and performance analysis of foldable bed in the furniture industry. For the determination of the size and installation position of the gas spring, the force analysis of the sideboard of the foldable bed can be further carried out by means of finite element analysis, so as to optimize the selection of the force arm of the gas spring.