US1911374A - Veneered door and like product - Google Patents

Description

May30, 1933. E, C LQETSCHER I 1,911,374

VENEERED DOOR AND LIKE PRODUCT 2 Sheets-Shevet 1 Filed June 12, 193C )fl muli May 30 1933- E. c. I oETscHER I VENEERED DOOR AND LIKE PRODUCT mets-Sheet 2 I l l l Il .Or A l l Il, A n. NNNNNNNNNNNNNNNNNN w 7 w 6, 7

'Patented May 3o, 4193.3 l

UNITED STATES EMIL C. LOETSCHER, 0F DUB'UQUE, IOWA V'ENEERED DQOR LIKE :PRODUCT Application led .Tune 12,

This invention relates to improvements 1n construction for wood veneered doors and like products, and to the process for manu-v facturin vthe same.

The o ject of the invention is to provide a new and novel construction for veneered products, such as doors, utilizing paper-thin sheets or plies of Wood as the veneering material, and 'in accordance with the general process described Vin a previous application filed by me on May 2, 1980, bearing Serial N o. 449,116.

Heretofore the art of wood veneering has been limited as to the thickness of the veneering materials used, the minimum being about M6 of an inch in ordinary commercial practice. Veneers of lesser thickness and approaching the texture of paper, although readily obtainable in commercial quantities and at a fraction of the cost of the thicker plies, have never found a practical use in the wood-Working industry, and particularly for veneering purposes. One reason for this isA the fact that veneering has been primarily a gluin operation, and thin sheets cannot be satis actorily glued. Again, owing to the, extreme thinness of the sheets, any unevenness or imperfections in the surface of the core would be readily apparent, a detriment that is difficult to overcome, inasmuch as it is uite impossible to produce a core with a per ectly smooth surface, even with great care being,y used in the planingi and sanding.

Moreover, wood veneering as practiced commercially, is an expensive process, since the veneer must be carefully trimmed and fitted to make smooth joints, and due to thickness of the material` the process is largely confined to fiat or plane surfaces, inasmuch as the veneer cannot be bent to conform to irregular contours without breakage or splitting of the fibers, andfmal-r ly lthe ordinary wood veneered surface is r su ject'to the same destructive forces that attack any finished wood surface, viz: moisture, heat and ordinary wear and tear.

' In accordance with the followin disclosure, however, it is possible not on y to use Wood veneers of paper thinnesspsay, from l door as taken on line 2`2 of Figure 1.

, attaching the sheets together.

1930. lSerial No. 460,563.

1/20 to 1/80 of an inch in thickness, in the manufacture of doors and like products, but to provide the article with a surface equal in appearance and finish to a finely finished piece of natural wood and superior in wearing qualities. v

A preferred embodiment of my invention is disclosed in the accompanying drawings, in which Figure l is a view in elevation of a finished door of the slab type of construction, showing the arrangement of the veneer sheets and the graining effect produced. Figure 2 is a view in section through'the Figure 3 is akview showing the materials assembled and placed Within a press preparatory to the finishing operation.

Figure 4 is a detail View of a sheet of thin Wood veneer made up ofl strips joined together at their edges, and showing the method of eliminating checks or blemishes that may occur in the veneer.

Figure 5 is a view in cross section through the sheet of veneer showing the method of y Figure 6 is an enlarged detailv view of a section of the door showing the manner in which the fibrous layer takes up unevenness in the surface of the core and veneer.

Figurev'? is a View in elevation of a panelled door made in accordance with the invention.

Figure 8 is an enlarged view in section through the door as taken on line 8 8 of 85 Figure 7, and

Figure 9 is a view showing the materials assembled in a press preparatory to the final l pressing operation in the making of a p anelled door. Referring to Figures 1 and 2, the door shown is preferably of the so-called slab type, that is, one of uniform thickness throughout and having smooth surfaces. The foundation of the door structure is a core 1 preferably of composite structure, made up of small blocks or units of soft wood la separated by thin strips 1b of Wood Iextending transversely of the thickness of the core. A core so constructed illustrates 10Q vfaces of the strips 2, 2 are preferably beveled,

- of manufacture.

so that they flare outwardly to an increased width at their outer or exposed faces, in fact, the width of these strips along their outer edges is substantially equal to the thickness j of the door.

On both sides of the core 1 is a layer Mof compressed fibrous material 3, 3 of a substantial thickness, but considerably less than that of the core. Ihe substance composing the layers'3, 3 is preferably a cellulosediber, such as cornstalk or wood lpulp processed into sheets or boards, or in place of an espe'- cially prepared produce, any one of several commercial products known generally as composite board and used extensively in building operations for wall insulation, may be employed. In .the finished door, as shown in Figure 2, these layers of fibrous materials have been subjected to considerably greater pressure than employed in Atheir original processing, and consequently have a density considerably greater and a thickness so'mewhat less, than they have in their natural state; in fact, their nal density may be said to approach that of a natural soft wood.

The surfaces of the fibrous layers 3, 3 are initially treated with a resinous substance, such as a natural rosin varnish or a solution of a synthetic resin, such as bakelite, the latter being preferred because of its superior qualities as a moisture and heat resistant. The treatment of the fibrous layers with the resinous substance will be explained in greater detail in connection with the process Over the surfaces of the fibrous layers 3, 3 are sheets of ordinary kraft paper 4, 4 which have likewise been treated or impregnated with a resinous substance, and again bakelite is preferred, in which case the term bakelizing may be used to describe the treat-- ment. And finally, over the surface of the paper sheets are the veneering sheets or layers 5, 5 consisting of paper-thin wood of any desired kind, such as walnut, mahogany or other hard and expensive wood used for- As heretofore indiornamental finishes. cated, wood suitable for veneering purposes can be readily produced commercially in exceedingly thin sheets of from 1/80 to 1/120 of an inchfr about that of ordinary tissue paper, althou h it has been of little use in the wood-working art, owing to its extreme thinness and the diiculty of satisfactorily applying to a surface as a veneer.

This paper-thin veneering material, as in the case of the layer of paper 4 lying just below it, is treated with a resin varnish, and preferably bakelite varnish, preparatory to its use, this treatment consisting of passing itthrough a bath of varnish or a bakelite solution, and then between pressure' rolls to remove the excess of the solution, and finally drying it in an oven, the heat driving off the solvent, leaving the wood thoroughly impregnated with the bakelite, which fills the pores and spaces between the fibers. Because of the extreme t-hinness of the sheets of wood veneer, they are usually handled and treated with the varnish in a wet or damp condition, so that the drying process also drives ofi' the moisture as well as the solvent in thefvarnish, leaving them quite dry except for a slight tackiness of the surface.

The sheets of the treated wood veneer are ordinarily smaller than the surface to be covered thereby, and hence it requires several sheets joined together to provide the veneer fora large surface area. Thus as shown in Figures l and 4, the veneeringmaterial is cut or trimmed into the form of strips 5a to extend lengthwise of the door, and assembledintov a single large sheet of a size to cover one side of the door. Accordingly the severalv strips 5a are arranged edge to edge and then joined together-by gummed paper strips 6 applied to their underside, as shown in Figures 5 and 6. Also ink handling these thin-sheets of veneer, cracks or checks 'develop where the fibers split, or imperfections in the wood cause openings to appear, as at 7 W'here these breaks or checks occur, it is a simple matter to eliminate them by applying small patches 8 of the same thin veneer underneath and securing them in place by the gummed strips, care being taken to match the graining as closely as possible.

Now, as previously explained, the layers v3, 3 of fibrous material are also treated with us having prepared the sheets of veV j neer and the materials for the under layers, all cut tothe proper size to correspond to the surfacearea of the corel, they are now assembled on opposite sides of the core preparatory to compression in an especially equipped hydraulic press.

Referring now to Figure 3, the several 13C layers of material are shown in their relative positions between the platens 9, 9 ofthe press, said platens being thick plates with passages 9a therethrough for the circulation of steam and cooling water. Between the platens and the assembled materials are thin plates 10, 10 having their contact surfaces carefully prepared and polished, the degree of polish determining the surface finish of the completed door.

The materials are assembled in the press with the layers 3, 3 of fibrous materialin contact with opposite faces of the core 1,

the sheets of paper 4, 4 over thebrous layable fibrous layer fills the depression when plied to the core.

ers, and the sheets of Wood veneer 5, 5 over the layers ofl paper. With the exception of the layer of fibrous material 3, 3, the several layers are non-yielding, and therefore do not undergo compression or reduction in thickness in the operation. The layers of fibrous material 3, 3, however, are capable of further compression to, say, one-half to one-quarter of their original thickness, and, therefore, are shown as being considerably thicker before the pressing operation (Figure 3). These fibrous layers, therefore, provide a yieldable cushion-like ply between the surface of the core and the outer layer of thin veneer, and serve primarily to com ensate for any unevenness in the surface o the core, on the one hand, and inequalities in thickness of the wood veneer,I on the other.

For eXample,lif there should be depressions in the core as at a, (Figure 6), due to some imperfection in its making, the yieldpressure is applied Without transmitting the unevenness to the surface layers. 'Similarly the fibrous layer presents a resilient foundation for the wood veneer, and again when pressure is applied, the additional thicknesses caused by the overla ping? f the edges and the application o the patches, together with lthe attaching strips of adhesive paper, are pressed into the resilient surface, with the result that the surface is perfectly smooth, as also shown in Figure 6.

In general, the press operation consists in subjecting the assembled materials to pressure and heat under conditions found by eX- perience to be most satisfactory. Thus, having applied an initial pressure, stream is allowed to circulate through the passages 9a in the platens 9, gradually bringing the temperature up to the point re uired to fuse and cure the bakelite impregnatmg the layers apcreased to a maximum of from 200 to .500 pounds per square inch, and maintained for a period of from 5 to 15 minutes, whereupon the steam is shut ofi:` and cooling water circulated through the platens, thereby reducing the temperature to Anormal before the pressure is released. r

The door is then removed from the press,

The pressure is then in` and is ready foruse without any additional polishing or finishing. As a result of the pressure and heat treatment the several layers of bakelite impregnated materials become firmly cemented together and to the surface of the core, forming in effect a composite covering Witha surface coating of the wood veneer backed by the paperand cemented to the fibrous layer. Again, the fused bakelite or resin, as the case may be, forms a hard colorless film, which in the case -of bakelite in particular, becomes infusible,

moisture and heat-proof, and capable of takingv on the natural smoothness and lustre of a polished natural wood surface.

As heretofore stated, the fibrous layers 3, 3 undergo substantial compression during the pressure treatment, and become quite as dense as the wood in the core, with slight variations wherever depressions or uneven spots are rectified either in the core or the external layer of wood veneer. The `fiber layers 3, 3 moreover preferably include a rosin sizing introduced during its preparation, which serves' as a binder as Well as a moisture repellant, and hence there is no tendency o f the fibers to expand after the pressure is removed, to cause subsequent swelling and consequent unevenness of surface. It may be desirable to bevel the edges ofthe fibrous layers 3, 3 at their edges, as at 3a, Figure 3, where they contact with the beveled or fiared edges of the edge strips 2, 2, so there will not be excessive compression at these points. Thus the edges of the door are substantially Wood throughout the full thickness, this being desirable in order to facilitate the mounting of the hardware, in that, the screws may haver anchorage in the wood rather than the fibrous material, although as a matter of fact the density of the fibrous layers is ample to hold the screw l threads.

thicker than the central portion, with por.

tions of varying thicknesses between, thus carrying out the same style of construction used in all-wood doors, namely, the thicker outer stiles and rails, the thin central panel and an ornamental moulding between.

Consequently the core, 12 in this case 1s made up inthe form of a frame of a Width to provide the lfoundation for the outer stile and rail portions of the door and the moulding, leaving a large central opening to be filled by the fibrous layers 13, 13, to form the central panel, these fibrous layers being the same as those described in connection with the slab door of Figures 1 and 2. Thus the core 12 in the form of a frame is beveled about `its inner edge to a cross-sectional lcontour of reduced thickness and conforming/T30 generally to the'stepped or offset contour of the moulding-like surface portion surrounding the thinner central panel.

Aside from the construction of the core, which otherwise is made up as before with the edge strips 14, the layers of fibrous material 13, 18, bakelized paper 15, 15, and thin wood veneer 16, 16, are treated, arranged and assembled upon the core, and subjected to pressure and heat treatment in the press, in the saine manner as previously described. However, there is a difference in the equipment used in the press, namely, the

l substitution of die plates 17, 1T for the flat pressure plates. These die plates have the impressions of the door surface sunk or cut on their opposed faces after the man-A ner of a molding die, so that when the pressure is applied the materials conform to the impressions, thus producing the cross section contour of Figure 8, even to the reproduction of miter joints at the corners of the moulding sections.

lt may be stated in this connectionl that the preparation of the sheets of wood veneer may be somewhat different in the manufacture of panelled doors than for slab doors,v

since it is the practice to take advantage of the graining to enhance the appearance. Thus the sheets may be cut into strips and assembled as before, with the grain running lengthwise of the stiles and rail portions as well as'the moulding portions, and mitered at theirl corners, while the central panel may have a different arrangement of graining or even different coloring, all of which is a matter of design and ornamentation.

The completed door has the same physical characteristics as the slab door, with the added features of the central panel composed of the two thicknesses of the fibrous layers compressed together and the numerous sharp bends and angles which the surface coating of wood Veneer makes in reproducing the effect of a moulding about the central-panel. This is a notable feature of the paper-thin veneering, namely, that it is so thin that it can be bent around sharp cor-f riority of bakelite, as the cementing agent` over glue or other adhesive used in veneering work. In the first place, glue does not afford protection to the surface of the article, while bakelite not only forms a perfect bond between the layers, but when cured forms a film impregnating the pores and lfibers of the surface layers of thin veneer and presenting a hard, infusible coating which resists heat, moisture and hard wear, and withall takes on a smooth natural finish which cannot be distinguished from a natural wood finish.

And again, bakelite will withstand high pressures without lessening its bonding or cementing properties, while glue and other adhesives arelimited as to pressure that can be applied in adhering surfaces together since they tend to vbe driven into the materials being joined, leaving the surfaces deficient in adhesion.

The product and process may be modified to the extent of omitting the impregnation of the thin sheets of wood veneer with the resinous adhesive or bakelite, and depending on the adhesive coating 011 the coated sheet of paper beneath the veneer to provide the .bond or adhesion of the two. This would be advantageous for some classes of work, since the veneered surface would then be in its natural state and could be later stained or otherwise finished to harmonize with the other wood work.

Having set forth a preferred embodiment of my invention, I claim:

1. A y'method of constructing doors and the like, consisting of forming a core of soft wood blocks and tapered marginal wood strips to provide the core with an increased thickness at its outer edges, applying layers of compressible fibrous material over the surfaces of said core, the surfaces of said 'layers having been previously coated with a phenol kcondensation product and their inner marginal portions being beveled to complement the taper of said strips, treating sheets` of paper and thin wood veneer with a solution of a phenol condensation product and applying the same over the layers of fibrous material with the wood veneer outermost, and subjecting the core with the superimposed layers and sheets to heat and pressure.

2. A method of constructing doors and the like, consisting of forming a core of soft wood with tapered marginal wood strips to provide the core with an increased thickness at its outer edge, applying layers of coinpressible fibrous material over the surfaces of said core, the edges of said layers having been beveled on the inner face to complement the taper of said marginal strips, applying av slightly beveled to complement the taper of said strips, applying layers of paper and an outer layer of thin Woodl veneer upon each layer of compressible fibrous material, the contacting surfaces thereof having been previously treated with a resinous varnish and dried, and subjecting the assembled materials to heat and pressure sulicient to bond the layers together and reduce the Whole to a predetermined thickness.

4. A method of construct-ing doors and thelike, consisting of forming a core of soft Wood, providing said core with marginal Wood strips tapered to an increased thickness at their outer edges, applying layers of compressible fibrous material over the surfaces of said core, the marginal portions of said layers having been previously tapered to a reduced thickness to complement the taper of the marginal strips of said core, applying sheets of paper over the surface of said layers of fibrous material and layers of thin Wood veneer over said layers of pa per, the surfaces of said core and/or the several superimposed layers appliedthereto having been treated With a resinous adhesive substance and subjecting the assembled materials to heat and pressure.

Signed at Dubuque, Iowa, this 7th day of June, 1930.

EMIL C. LOETSCHER.

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