Category The History of Furniture Construction

8.2.1 Properties of Hyperelastic Polyurethane Foams

Hyperelastic polyurethane foams are produced in the process of foaming polyure­thanes, with the use of cross-linkers, foaming agents and catalysts. In the produc­tion of these types of foams, it is important that after seasoning the block, a mechanical opening of closed pores takes place. Properly opened pores provide the level of flexibility of the foam.

Foams are one of the basic materials used in the construction of subassemblages of upholstered furniture, both with springs and without springs. In particular in the latter, polyurethane foams form an essential part of the upholstery construction...

8.1 Stiffness and Strength of Upholstery Frames

Frames of upholstery furniture belong to 3D structures, made of rails not lying in one plane, or 2D frames, but loaded with forces not lying in the system plane. (Fig. 8.1).

The general principles and proceedings when solving frame 3D systems with the method of forces are the same as with solving 2D frames (see calculations on the side frames of chairs). First, the degree of static indeterminacy ns should be determined:

ns = p + 6t — 6,

where

p number of support nodes,

t number of necessary cuts of closed contours and 6 number of equilibrium equations for any 3D force system

Therefore, the frame presented in Fig. 8.2 is a 19-fold statically indeterminate system ns = 19.

Then, the frame of references x, y, z should be assumed, so that as man...

• Natural and faux leather have a protective layer, but the use of inappropriate cleaning agents may cause damage to the cover. Therefore, under the threat of losing the warranty, the leathers have to be protected against solutions such as alkaline, acidic, etc. Instead, use solutions recommended by: (name of a company).

• The frequency of cleaning the leather depends on the intensity of use of the furniture. Fresh contaminations can be removed immediately using a clean, dry cloth or tissue. If these methods prove ineffective, one should use solutions recommended by (name of a company).

Protection and care of fabrics in upholstered furniture:

• It should be regularly cleaned, vacuumed, and in the case of fabrics with hair, the furniture cover should be brushed;

• Colourants used to ...

• Complying with the requirements given in this instruction will allow the long-term and fail-safe use of the furniture;

• When moving the furniture, all upholstered elements must be secured, so that they are not subject to mechanical damage;

• When unpacking the furniture, do not use sharp tools, as there is a danger of mechanical damage of the upholstery material;

• When moving the furniture, always hold them underneath at stiff elements of the bearing structure;

• It is not allowed to drag or lift furniture holding it at the lining or cushions;

• Furniture should be used in accordance with their intended purpose;

• Furniture should be used in dry, enclosed spaces, protected from adverse weather conditions and direct sunlight;

• Upholstered furniture must be placed within m...

• The condition for the extension of the warranty period is purchasing a service package,

• In order for the warranty to gain validity, it is necessary for the seller to fill in the data relating to the transaction and product,

• The warranty is valid, provided that the buyer observes the instructions attached to the furniture, concerning use, regular cleaning and maintenance,

• The warranty covers only residential furniture used in home conditions,

• The warranty is valid on the territory of Poland,

• The warranty does not cover changes of softness of cushions and shrinking of the cover material, being the result of normal use of the furniture,

• Characteristic features of furniture made entirely from natural leather or in combination with other materials, such as faux leather...

The document obliging the producer to provide periodic, free service repairs is a warranty card. This document should normally include:

• the name of the product or its components covered by the warranty,

• the warranty period for the entire piece of furniture or its components,

• starting date of the warranty validity,

• the territorial area of the warranty validity,

• the warranty conditions, that is the requirements, which fulfilment maintains the warranty services of the guarantor or which unfulfilment causes the loss of these services,

• a description of the complaint procedure, which is a precise description of the acceptance and processing of the complaint and the manner of the implemen­tation of furniture repair,

• description of the furniture construction,

• descrip...

7.3.1 Reliability of Case Furniture

The European Union Directive No. 2001/95/EC, relating to general product safety, includes also furniture. The appropriate European norms define safety requirements for the use of furniture; however, they do not apply to the evaluation of the

construction reliability at an extended period of time of their use. The use of traditional methods of designing and evaluating the strength requirements for fur­niture, based on subjectively accepted safety coefficients and certainty reserve, does not allow to judge the time and probability of damage to the furniture or its element...

Doors of horizontal rotation axis are used in furniture fulfilling the function of bars and davenports. Their work tops in addition to mass and concentrated loads also shift the load equally distributed on the surface of the board. The strength of the door suspension is determined by the hinges mounted in horizontal partition of the body. A tangible indicator of this strength is the value of the force aiming to break out the hinge box from the partition. Taking into account the actual conditions of the furniture use, two calculation schemes can be applied. The first, shown in Fig. 7.78, describes a condition in which a correctly operating guide shifts

operational loads, at the same time relieving the box hinge...

Criterion of strength for hinged doors of vertical rotation axis is the value of force resulting in breaking out of the hinge form the slot made in the particle board constituting side wall of the body. Distribution of internal forces acting on the hinge

has been shown in Fig. 7.76. Taking into account the weight of the door, the resultant W of the forces RA and HA acting on the lower hinge must be determined:

where

W resultant force,

P operational load,

V volume of the door board, p density of element material, g 9.81 m/s2, h height of the door, a height of the setting of hinges and b width of the door.

Results of studies on the strength of box hinges mounted in particle boards of various densities indicate that the criterion of strength for hin...

Wall cupboards, especially bathroom and kitchen cupboards, are attached to the walls with the use of furniture handles screwed to the body, top or simultaneously to the top and side wall using screws (Fig. 7.75). Embedded in the wood, they should be screwed into the properly drilled holes with a diameter 2 mm smaller than the diameter of the screw core. Drillings should be made on a section of about 80 % of the length of the screw. In structures made of particle boards, drillings are not used.

Because screws of handles of metal wall cabinets work on bending and shearing, the number t of single-sheared screws should be determined from the equations:

Fig. 7.75 Methods of mounting cupboards

where

t number of single-sheared screws, d screw diameter,

Vt volume of element,

Pi density of element ...