This paper presents an approach to the design of an upholstered furniture frame using the finite element method and empirical studies. Three-dimensional discrete models of upholstered furniture ...frames were developed taking into account orthotropic properties of solid pine wood (Pinus sylvestris L.) without and with details strengthening their structure in the form of glue joints and upholstery staples. Using the CAE Autodesk Inventor Nastran finite element method, linear static analyses were performed by simulating normative loading. The finite element method was performed considering the experimentally determined stiffness coefficients of the PCAC adhesive and staple joints. As a result, stress, displacement, and equivalent strain distributions were obtained for upholstered furniture frame models with stapled corner joints. The deformation and strength behavior of the upholstered furniture frames was improved by reinforcing with a wood strip. A new approach to the design of upholstered furniture frame frames using the FEM method with stapled component connections was developed and tested. The results of the study can be applied in the optimization of upholstered furniture construction.
This paper presents the strength properties of wooden trusses. The proposed solutions may constitute an alternative to currently produced trusses, in cases when posts and cross braces are joined with ...flanges using punched metal plate fasteners. Glued carpentry joints, although requiring a more complicated manufacturing process, on the one hand promote a more rational utilisation of available structural timber resources, while on the other hand they restrict the use of metal fasteners. The results of the conducted analyses show that the proposed solutions at the current stage of research are characterised by an approx. 30% lower static bending strength compared to trusses manufactured using punched metal plate fasteners. However, these solutions make it possible to produce trusses with load-bearing capacities comparable to that of structural timber of grade C24 and stiffness slightly higher than that of lattice beams manufactured using punched metal plate fasteners. The strength of wooden trusses manufactured in the laboratory ranged from nearly 20 N/mm2 to over 32 N/mm2. Thus, satisfactory primary values for further work were obtained.
An upholstery frame is an element of upholstery furniture, which is heavily loaded with forces. Critical to the quality of the frame is the load capacity of the connections of its structure elements. ...Moreover an important issue is the repeatability of the suitable strength in the whole production batch. Tested wooden frame joints were made with glue and staples. The goal of our study was to compare the strength of the joints made by a man and by a robot in industrial mass production. The laboratory test was done on an universal testing machine which measure the stress–strain characteristics showing the yield behaviour of test samples. The results show that a “robotic technology” gives slightly higher strength values than the manual production. It was also observed that the force value distributions in compared two series of samples have different nature in the both technologies. Based on the observation of the technologies and based on the analysis of the research results, it was found that the reason for this is the greater constancy of technological parameters in robotic production (in the described case, the bigger variability of the strength of connections made by man was caused by the different exposure time of the adhesive to drying, while in “robotic” production gluing, was done in the same throughout the long production series).
A robotization of assembly is the real implementation of Industry 4.0 in the furniture industry. The robotization objective is to obtain favorable values of production process parameters ...(performance, productivity, quality) and to improve human wellbeing at work. Our aim was to present and compare the quality parameters of a selected furniture production process, performed in a very long series, containing more than 30 thousand products. The analysis included the results of the long-term measurements of the quality level of upholstery frames produced by the modified and improved, on the basis of operational conclusions, robotized line for the serial production of upholstery frames and by the simultaneously used nonrobotic line for assembly of frames of the same construction. The results obtained show that robotized assembly leads to a much lower percentage of defective products than in the case of the nonrobotic technology, the causes and types of defects in the products are also different, and it is easier to prevent these defects and remove them. The cognitive findings identified problems and challenges, not found in traditional technologies, caused by the using of manufacturing robots in furniture production.
Machine processing parameters, including the feed speed and the working speeds of tools, are determined by: the minimum demand for material in a specific branch of the furniture industry, the ...expected quality, as well as the form and type of wood processed. Due to the considerable diversity of physical and mechanical properties of raw wood there are high demands concerning process and machine individualisation in technology planning. Setting the right processing parameters is necessary to make high-quality semi-finished and finished products. In order to increase the precision of machining specialised tool and transport systems need to be used. At the same time, the increase in the required production efficiency is inversely correlated with the individual characteristics of the raw material and the desired indicators of the quality of products. A harmonised level of these parameters is the main assumption in the selection of machine tools and auxiliary devices. The analyses conducted in this study showed that there are numerous variables in methods of selecting machines and devices for raw wood processing. When selecting machining systems, enterprises should use a system of weights to indicate which elements (quality and dimensions or efficiency) are of primary importance for them.
An ergonomic seat or bed must be capable of supporting optimally and evenly the user’s body for sustained periods of time. The objective of the performed nvestigations was to ascertain the impact of ...natural aging on the stiffness of polyurethane foams in dwelling apartment conditions and, additionally, to determine regression equations describing this dependence. Seven types of furniture foams, differing with respect to their apparent density and stiffness, were selected for the experiment. Experimental foams were exposed to aging for the period of 730 days (two years) in climatic conditions typical for dwelling facilities. Foam stiffness was determined in a uniaxial compression test determining strain characteristics in the function of deformations. The performed experiments made it possible to establish percentage changes of stiffness of some foams as well as the time required for those changes to assume a significant character.
Ergonomsko sjedalo ili ležaj mora biti sposobno optimalno i ravnomjerno podržavati korisnikovo tijelo dovoljno dugo vrijeme. Cilj provedenih istraživanja bio je utvrditi utjecaj prirodnog starenja na ...čvrstoću poliuretanske pjene u stambenim uvjetima, a osim toga, i utvrditi regresijske jednadžbe koje opisuju tu ovisnost. Za eksperiment je odabrano sedam vrsta pjene za namještaj različite gustoće i krutosti. Odabrane su pjene izložene starenju u razdoblju od 730 dana (dvije godine), u klimatskim uvjetima tipičnim za zatvorene stambene objekte. Krutost pjena utvrđena je jednoosnim kompresijskim testom određivanja ovisnosti naprezanja o deformaciji. Provedenim je eksperimentom moguće utvrditi postotak promjene krutosti neke pjene, kao i vrijeme potrebno da te promjene postanu značajne.
An ergonomic seat or bed must be capable of supporting optimally and evenly the user S body for sustained periods of time. The objective of the performed investigations was to ascertain the impact of ...natural aging on the stiffness of polyurethane foams in dwelling apartment conditions and, additionally, to determine regression equations describing this dependence. Seven types of furniture foams, differing with respect to their apparent density and stiffness, were selected for the experiment. Experimental foams were exposed to aging for the period of 730 days (two years) in climatic conditions typical for dwelling facilities. Foam stiffness was determined in a uniaxial compression test determining strain characteristics in the function of deformations. The performed experiments made it possible to establish percentage changes of stiffness of some foams as well as the time required for those changes to assume a significant character. Key words: aging, polyurethane foam, stiffness Ergonomsko sjedalo ili lezaj mora biti sposobno optimalno i ravnomjerno podrzavati korisnikovo tijelo dovoljno dugo vrijeme. Cilj provedenih istrazivanja bio je utvrditi utjecaj prirodnog starenja na cvrstocu poliuretanske pjene u stambenim uvjetima, a osim toga, i utvrditi regresijske jednadzbe koje opisuju tu ovisnost. Za eksperiment je odabrano sedam vrsta pjene za namjestaj razlicite gustoce i krutosti. Odabrane su pjene izlozene starenju u razdoblju od 730 dana (dvije godine), u klimatskim uvjetima tipicnim za zatvorene stambene objekte. Krutost pjena utvrdena je jednoosnim kompresijskim testom odredivanja ovisnosti naprezanja o deformaciji. Pro- vedenim je eksperimentom moguce utvrditi postotak promjene krutosti neke pjene, kao i vrijeme potrebno da te promjene postanu znacajne. Kljucne rijeci: starenje, poliuretanske pjene, krutost
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