Abstract:
A hot-air generator to facilitate execution of work on plastic spectacle frames, having two axial, parallel and opposing hot-air outlets.

Description:
BACKGROUND OF THE INVENTION 
     Well known is the equipment used in optical work for heating the plastic frames of spectacles to soften them and make it possible to shape them to the desired form both temporarily or permanently. 
     This is done to adapt the frames to fit the lenses and suit the face when the lenses are first mounted or when the spectacles need repairs. 
     A draught of air, passing through electric elements, heats the frames when it emerges from an outlet meeting one side of the frames to be softened. 
     This means that the operator must repeatedly turn the frames over in relation to the source of heat both to speed up the work and to warm the frames evenly. 
     The necessity to repeat this action clearly makes the work slower and more complex; further, it proves almost impossible to keep the frames uniformly and continuously heated. 
     The above invention eliminates the above drawbacks and provides considerable advantages as well, as will be described below. 
     SUMMARY OF THE INVENTION 
     Subject of the invention is a hot-air generator for the process of assembling plastic spectacle frames, at the working surface of which there are two hot-air outlets, in a pair, perpendicular to the working surface, parallel and counterposed to each other. A chamber is thus created in which to place the part of the frames to be treated, such part receiving warm air simultaneously on one side and on the other and especially on the front and on the back. 
     This hot-air generator employes a cylindrical fan with tangential blades and electric elements placed parallel to the blades of the fan. 
     The work surface area, lying between the opposing hot air outlets, is formed of a grating placed above the heating elements and parallel to them thus giving rise to a third hot air outlet between the first two opposing outlets, and perpendicular to them. 
     The shape of the air inlet aperture is practically rectangular and this aperture lies parallel to the fan. The cylindrical fan is housed in a cylindrical chamber that carries the air, sucked in through the rectangular inlet lying parallel to the fan, into a parallelepiped shaped chamber housing the electric elements at the top of which chamber there is a long rectangular aperture it too being parallel to the fan and having in its central part a grating which forms the work surface. 
     The two paired and opposing outlets of hot air consist of two air conveyors placed at the two ends of the rectangular outlet aperture for hot air lying over the electric elements, the base of each conveyor being open above the electric elements and parallel to them for air entry, and each conveyor having an outlet aperture perpendicular to such base. 
     By means of the rectangular aperture for entry of cold air, of the cylindrical fan parallel to the first aperture, of the electric elements parallel to the fan and of the rectangular hot air outlet parallel to the elements, a flow of hot air is produced, having a rectangular cross section, directed towards the work surface, and this flow passing through the conveyors divides into two streams which change direction, almost by 90 degrees, the one turning to meet the other in the area where the spectacle frames are placed for treatment. 
     The two conveyors referred to above substantially consist of a box-shaped body comprising two parallel sides the width between them being that of the rectangular aperture of the parallelepiped chamber containing the electric elements, and of a cover formed by a back wall sloped and joining a curved wall at the top. 
     This cover is substantially opposed to the flow of air coming from the electric elements, and has the effect of changing its direction by almost 90 degrees. 
     Suitable and well-known devices are provided for regulating the speed of fan rotation, the quantity of heat given off by the electric elements and the temperature of the hot air. Screened areas exist on the grating above the electric elements to prevent, if necessary, direct heat from the elements reaching the spectacles placed in the work space on the grating itself. 
     The characteristics and the purposes of the invention will become even clearer by the following example of its execution accompanied by diagrammatic drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1: the equipment seen in perspective from outside 
     FIG. 2: the equipment seen in perspective from inside 
     FIG. 3: transversal cross section 
     FIG. 4: longitudinal cross section 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The equipment includes the outer casing (10), the working surface (11) on which the spectacles stand, the aperture (12) for entry of air, the fan (13) with tangential blades (14) turned by the electric motor (15), a certain number of electric elements (16), supported by insulating diaphragms (17) and placed parallel to the blades for their entire length. 
     A rectangular aperture (18) for air outflow, about as long as the elements themselves, is provided on the work surface. 
     The two conveyors (19) and (20) are situated at the two ends of such aperture with their vertical and opposing outlets (21) and (22), provided with gratings that convey the inflowing air, divided into two streams one directed towards the other. 
     Between outlets (21) and (22) lies the horizontal grating (23) placed over the central part of the heating elements. The width of the conveyors and the size of the work surface (11) are sufficient to allow the spectacles (26) to be placed for treatment as shown in FIG. 1 and diagrammatically in FIG. 4. 
     Each conveyor (19) and (20) is formed of a box-shaped body with a wide open base coinciding with the ends of the aperture (18) for the flow of hot air, and comprising the outlets (21) and (22) for hot air, perpendicular to the base, two parallel sides (24) and (25) substantially coinciding with the side edges of the oblong aperture (18), and back wall (27), sloped, and an upper roof (28) joined to the back by the piece of curved roof (29). 
     The rocker switch (30) starts the electric motor causing cold air to be sucked in. 
     The rocker switch (31) turns on the electric elements. 
     The rheostat (32) enables fan speed to be increased or reduced. 
     The fuse (33) protects the circuits. 
     As clearly shown in the figures, the cylindrical fan (13) is housed in the cylindrical chamber (34) which, as it approaches the elements, becomes a parallelepiped (35) until it joins the rectangular opening (18) above these elements. 
     Mode of operation 
     Cold air is sucked in through the aperture (12) with its grating, and heats up as it passes through the electric elements. 
     Air delivery, its force and temperature, can all be regulated at will. 
     The heated air comes out from the opening (18) above the elements and, due to the effect of the conveyors, divides into two streams one directed towards the other as shown by the arrows A and B in FIG. 4, while a third stream, coming up from below, flows as shown by the arrow C. As a consequence the spectacles (26), placed between the two conveyors, seen in perspective in FIG. 1 and drawn diagrammatically in FIG. 4, are simultaneously reached by hot air both back and front and from below as well. 
     Advantages 
     The spectacle frames are heated uniformly without any need for turning them over as is required with present heating equipment. 
     Heating itself is also uniform avoiding the risk of setting up harmful stresses in the plastic. 
     The work can therefore be done much better and more quickly. The spectacles have a longer life and the present liklihood of their getting out of shape, due to internal stresses, is avoided. 
     As the applications of the invention have been described purely as an example in no way limited to this, it is understood that any equivalent application of the inventive concepts explained and any product executed and/or in operation according to the characteristics of this invention, will be covered by its field of protection.