| The dis-assembly structure furniture design is the general trend along with the rapid development of society and continuous progress of science. And the structural strength design of dis-assembly furniture products are highly valued by the furniture manufacturers and related research department.Component nodes design as the most important content of Lignum Catalpa wood furniture structural strength design, its joint strength study becomes the key part. Four in one connector joint is one of the main methods of joining used in dis-assembly Lignum Catalpa wood furniture, and the tensile strength, bending strength, compressive strength as well as the torsional strength can intuitively reflect the joint strength. Due to limited conditions, only the tensile strength, the breaking bending moment of bending strength and the bending rigidity that give the biggest influence to the whole furniture structural strength are discussed in this paper.The results of single factor experiment show that:Both of the transverse and longitudinal joint get the largest ultimate pullout force of metal pre-embedded nut when the guide hole diameter ratio is 90%, the thread length is 30mm, the thread distance is 2.5mm and the screw diameter is 14.5mm. And the transverse joint ultimate pullout force of metal pre-embedded nut is 27% higher than the result of longitudinal joint.The orthogonal optimization experiment results show that:The ultimate pullout strength effect of different elements to metal pre-embedded nut of Lignum Catalpa component transverse joint is L>P>r>D, That is the most obvious effect of the pre-embedded nut is thread length, and the thread distance take the second place. The element of guide hole diameter ratio is the third one, and the screw diameter has the smallest influence. The optimum factor level is Z3/V2.D3 . Analysis of variance indicated that the most significant effect on the test results is the thread length, and screw diameter has the smallest influence. Combined with the difficulty degree of the actual assembly process and the assembly efficiency, the optimization of orientation is that the guide hole diameter ratio is 90%, screw thread length is 20mm, the thread distance is 2.5mm and the screw diameter is 11.5mm.The anti bending test results show that:The best anti bending performance in the 4 joint ways is the Four-in-one connector joint on the node and its average bending strength can reach 1749.2N. The positioning round tenon take the second place when the connection joint on top of it. Double positioning round tenon take the third place when connection joint on middle position. The bending performance is the minimum when connection joint on the lower position, and its average bending strength is only 577.6N. The experimental analysis results show that:The average bending properties of "T" type rectangular components is 20% higher than "L" type rectangular components. So we should give priority to the "T" type node and minimize the use of "L"type joint when we carry out the Lignum Catalpa wood furniture structural design.According to the joint strength comparison experiments of Four-in-one connectors with the removable double round tenon connection that’s common on the current market, and the results indicated that:The average tensile strength of double Four-in-one connector is 27.5% higher than the double round tenon joint. The average breaking bending moment of double Four-in-one connector is 21.45% higher than the double round tenon joint. The average bending rigidity of Four-in-one connector is a little lower than double round tenon joint, and the difference is 10.6%. To sum up, it’s feasible to replace the double round tenon joint with Four-in-one connector according to the integrated results of tensile strength and bending strength experiments. |
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