In the preparation of foam rubber or polyurethane foam slabs or slabs formed of related materials which are used as a base for tufted, upholstered furniture cushions and backs and/or related products, it is necessary to provide in the foam slabs a pattern of holes where buttons are to be applied and/or through which tufting pins are inserted during the upholstery operation. Where tufting pins are used, they are inserted through the upholstery and pulled tight, and the upholstery fabric is creased or folded between the pins which, if allowed to remain in view, will make an unsightly final product. It is therefore conventional to form slits in the foam rubber extending partially through the thickness of the slab and radially from the holes forming the exterior perimeter of the pattern, and in some cases, between the inner holes in the pattern. The creases and folds in the fabric, as it is pulled tight, work their way into the slits, so that they are not visible in the completed chair back or cushion. Further, in certain sewn patterns (bisquit designs), there are no buttons or tufting pins, however slots are necessary for the reasons hereinabove mentioned.
According to conventional, known methods, such holes may be drilled manually through an overlay pattern with a hand drill, the pattern used to chalk mark the slot lines, then removed and the slots manually sawed with an electric saw knife or formed with a razor or knife-like blade. These methods are time consuming, and since performed and laid off by hand, generally inaccurate. Other known methods for forming the holes are by use of a punch press with male and female dies and by use of a steel rule die. The thickness of the foam slab in such punching processes is limited, and moreover, the slots must be laid off and cut in a separate operation. There is no known apparatus for performing this operation according to an automated process.
The present invention, on the other hand, is directed to an apparatus for automatically preparing the foam slabs by forming the holes of the pattern and the slits extend transversely and longitudinally from the holes forming the periphery of the pattern. Diagonal slots must be formed in a separate operation which is not within the scope of this invention. In this regard the apparatus includes an operating head mounted for reciprocal movement in a vertical path above a horizontally reciprocal table. The table includes indexing means associated therewith for shifting the table past said operating head at prescribed increments. The operating head includes a plurality of vertically reciprocal frames or brackets, each of which has mounted thereto one or more rotary cutters and/or saw which may be operated individually or simultaneously with each other. As the table indexes past the operating head a switch means associated with the table activates selected sets of cutters and saws to automatically form a prescribed pattern of holes and slits in the foam. In one embodiment of the apparatus switch-engaging elements are attached to the reciprocating table at intervals equal to corresponding longitudinal dimensions between adjacent hole or slit repeats in the foam slabs and are brought into engagement with a switch means as the table is indexed. The switch means is electrically connected to the operating head so that as various switch-engaging elements engage the switch means, prescribed frames or brackets containing drills and/or saws are activated.
The reciprocating table is indexed by means of a control rod attached to the underside thereof having a plurality of longitudinally spaced collars thereon which are sequentially engaged by an indexing lug pivotally attached to the piston of an air cylinder. As the piston is activated, the lug is in an upright position and engages one of the collars of the control rod, moving the table forwardly a prescribed distance. As the piston is retracted on the return stroke, the lug is pivoted down out of the way to pass beneath the succeeding collars and held down by an adjustable cam plate until the piston begins its next forward stroke, whereupon it returns to its upright position and engages the next succeeding collar. An air brake facilitates the stopping of the table at the end of each stroke and is activated by means of a limit switch attached to the piston which engages a switch element associated with the brake.
Hold down means are associated with each cutter and saw set, which rest against the surface of foam slab to hold the foam slab in position as the knife or drill is withdrawn. The hold down means floats on rods depending from the operating head or are spring biased so that they remain in engagement with the foam slabs for a brief period of time after the drill and knives have cleared. Also the hold downs engage the foam slabs at a point in time before the cutters and saws engage the foam to prevent the skewing of the slabs by action of the cutters and saws.
At the end of travel of the reciprocal table, a return air cylinder is activated to return the table back to its initial position. The cutting tools themselves are provided with a tapered side wall which affords a relief angle between the cutter tool and the foam wall surrounding the opening being formed as well as allowing the saws to be mounted on the same frame for "in line" slitting. An extractor extending axially within each cutter pushes out the cut foam plugs at the end of the cutting operation.
It is therefore an object of the present invention to provide an apparatus for automatically forming a prescribed pattern of holes and slits in foam slabs preparatory to an upholstery operation.
It is a further object of the present invention to provide an apparatus of the type described, wherein a foam slab positioned on a table is indexed horizontally past a vertically reciprocal operating head including a plurality of sets of rotary cutters and saws mounted thereon, each set being activated according to a preselected sequence to form a prescribed pattern of holes and slits in the foam slabs as they pass therebeneath.
It is still a further object of the present invention to provide an apparatus of the type described, wherein the positioning of rotary cutters and saws on said operating head may be varied so that a variety of patterns may be formed automatically as the foam slabs pass through.
It is still a further object of the present invention to provide an apparatus of the type described further including a table indexing means for moving the table a prescribed distance upon each activating thereof, and a return means for returning the table to its initial position after the operation is completed.
Another object of the present invention is to provide an apparatus of the type described further including a hold down means associated with the operating head to engage the foam slabs and prevent skewing thereof during the operation.
Another object of the present invention is to provide an improved rotary cutting tool for forming cylindrical openings through foam rubber slabs.
Yet another object of the present invention is to provide an apparatus of the type described including an improved connecting means between the reciprocal table and the bed on which it rests.