US3249739A - Sheet heating apparatus - Google Patents

Description

y 3, 1966 L. PHILLIPS 3,249,739

SHEET HEATING APPARATUS Filed Nov. 19, 1963 2 Sheets-Sheet l INVENTOR Lawrence Phillips BY EMJ ATTORNEYS y 3, 1966 L. PHILLIPS 3,249,739

SHEET HEATING APPARATUS Filed Nov. 19, 1963 2 Sheets-Sheet 2 x, INVENTOR Lawrence Phillips ATTORNEYS 3,249,739 SHEET HEATING APPARATUS Lawrence Phillips, Silver Spring, Md., assignor of fifty percent to Stanley Paymer, Silver Spring, Md. Filed Nov. 19, 1963, Ser. No. 324,662 Claims. (Cl. 219-218) The present invention relates toheating structures of the type adapted to heat, for example, sheet plastic materials; and is more particularly concerned with an apparatus adapted to be used in various manufacturing, covering, recovering, and upholstering techniques wherein it is desired to maintain sheet material in a semi-softened and/ or pliable condition while it is being otherwise manipulated.

Various manufacturing and covering techniques contemplate the use of sheet plastic materials, e.g., sheet vinyl,

as the covering medium. Such material is employed, for

example, to cover the bottoms and backs of chairs, in which event it is known that a sheet of plastic material can be appropriately shaped about a supporting form, such as a molded form of foam rubber material, and secured in place. In recovering operations, moreover, it is customary for existing bottoms or backs of chairs or similar funituIe to be separated from the furniture frame, stripped of existing worn or soiled covers, and then recovered by the manipulation of decorative and protective sheet plastic material about the preexisting bottom or back form.-

In manufacturing, covering, and reupholstering techniques of the types described, persons have sometimes attempted to work with sheet plastic covering materials while such materials were at room temperature. It has been found, however, when such sheet material is worked at room temperatue, that the resulting covered article is often wrinkled in part and unsightly, particularly adjacent those portions of the article where the sheet material had been pulled tight for fastening purposes.

In an effort to obviate such wrinkling and unsightliness, and to otherwise obviate distortions in the covering material, persons dealing with such sheet plastic material in furniture manufacturing and article covering operations have sometimes heated such material prior to working therewith. Sheet plastic material, when so heated, softens somewhat; can accordingly be stretched more tightly about a form or supporting structure; and may, in theory at least, therefore be permanently fastened in place without wrinkling, puckering, or the like. The heating apparatuses and techniques used heretofore have, however, prevented full realization of this objective.

Sheet plastic heating operations of the type described have generally been conducted in either of two ways. In a first technique, persons handling sheet plastic material have placed the sheet material in a heat box, permitting it to be elevated to a proper temperature; and then have removed the heated sheet material from said heat box to work it over a supporting form. The second technique has contemplated the use of a hand gun adapted to blow heated air upon localized portions of the sheet plastic material whereby one working with such material may cally heat portions of the material in the course of manipulating the same thereby to perm-it the material to be stretched. Each of these techniques, conventional heretofore, has been subject to significant disadvantages.

It is known, for example, that many sheet plastic materials of the type employed in furniture and other plastic covered articles are embossed with designs or patterns,

' or with other decorative surface configurations, or that they are multi-colored in nature. The heat box and/or the hand gun techniques utilized heretofore ordinarily result in localized stretching of the plastic material, with resultant distortion in the embossed or colored pattern which characterizes the material. More particularly, upon United States Patent 0 ice removal of a heated sheet from a heat box for purposes of subsequent manipulation, some cooling is experienced in at least portions of the material by the time that manipulation thereof actually commences. Such cooling, which occurs irregularly in the material, results in variable stretch-ing of the material at the various different temperature portions thereof with resultant distortion in the pattern of the material. This result has, moreover, been experienced in the case of hand guns which, by their very nature, achieve localized heating only, thereby permitting localized stretching of the material only; and those portions of the sheet material which are so heated have been found, after such manipulation, to exhibit pattern distortions.

The present invention, recognizing the foregoing problems, is concerned with an improved apparatus which is adapted to effect heating of sheet plastic material for the purposes described, and which, more particularly, is designed to heat sheet plastic materials uniformly throughout and to maintain such sheet plastic material in a uniformly heated condition during subsequent manipulation thereof, whereby any stretching of the material is effected substantially throughout thematerial rather than at 10- calized portions thereof. Moreover, the apparatus of the present invention is intended to permit manipulation of the material without interference with the heating function thereof, and vice versa. The resultant product, manufactured with the apparatus of the present invention, ac-

cordingly eliminates and avoids the wrinkles and pucker ing which have followed manipulation of'unheated sheet plastic material, and simultaneously avoids the pattern distortions which have characterized locally heated and/or variably heated and cooled materials manipulated heretofore.

It is accordingly an object of the present invention to provide an improved sheet heating apparatus adapted to maintain sheet material at an elevated substantially; uniform temperature while simultaneously permitting manip ulation thereof.

Another object of the present invention resides in the provision of a sheet working apparatus adapted to facilitate the manufacture of various plastic articles and, more particularly, the manufacture of sheet plastic covered articles.

Still another object of the present invention resides in the provision of an apparatus adapted tobe used with patterned sheet plastic materials and adapted to avoid pattern distortions in such materials during manipulation thereof.

A further object of the present invention resides in the provision of an improved heating and manipulating apparatus for use in the manufacture and/or covering of furniture articles or the like.

i A still further object of the present invention resides in the provision of an apparatus designed to permit sheet plastic materials to be heated substantially uniformly throughout, and designed, moreover, to permit the heating temperature to be preselected and/or varied asdesired, thereby rendering the apparatus usable with a variety of materials. j

In providing for the foregoing objects, and others which will appear hereinafter, the present invention con templates the provision of a sheet working apparatus comprising a freely rotatable turret or ta'ble constructed of a heat conductive material. The said freely rotatable table is mounted on an appropriate supporting platform in association with a variable heat supply adapted to heat said table; and adapted, moreover, through the provision of an appropriate reflective surface or hood, to project heat to locations spaced above the table, all without interfering with the working area of the table itself. .By this arrangement, the table "is substantially uni- 3 formly heated whereby plastic sheet materials may be placed upon the table to be similarly heated; and the table may, moreover, be readily moved in various directions at the will of the operator to permit the sheet ma terial to be manipulated as desired relative to a supporting form placed on said table. means effecting a flow of heat above the surface of the table, moreover, assures that the sheet plastic material holds its temperature even if it should be lifted away from the table in the course of manipulation, thereby avoiding the localized cooling and pattern distortion effects which have characterized arrangements utilized heretofore.

As will also appear hereinafter, the arrangement employed with the apparatus of the present invention is designed to heat the working surface or table, and the region above it, to various temperatures which may be readily altered with changes in the material being worked and/or with changes in the ambient temperature (i.e., between summer and winter). As a result, an appropriate temperature range may be readily selected to permit proper operation of the apparatus under a variety of possible working conditions. In practice, the apparatus of the present invention is utilized by placing a sheet of plastic material, face-side or pattern-side down, on the heated work surface or table whereby said material is itself heated throughout. An appropriate supporting form, e.g., a premolded foam rubber *or padded chair bottom or back may thereafter be placed on the sheet material, whereafter the sheet material may be folded about the form and pulled up 'at the corners or sides thereof to tightly enclose the form. As the material is so pulled at the corners and sides of the form, it is stretched; and the substantially uniformly heated condition of the sheet material tends to assure that it is stretched substantially throughout its entire width, thereby avoiding and/or minimizing pattern distortions. The material so manipulated and stretched may be permanently fastened in place, e.g., by means of a power stapling gun, whereafter the covered form may be removed from the table. The cover material quickly cools after removal from the work surface or table; and the resultant article then comprises a supporting form very tightly encapsulated in the sheet cover material, with substantially no Wrinkles or puckering and with substantially no pattern distortion.

By'use of the apparatus, covering operations can be effected far more rapidly, and less expe-nsively, than has been possible heretofore, particularly since extreme care is no longer necessary to assure the avoidance of wrinkles or the like. Moreover, the resultant covered product is far better in appearance and structural configuration than has been the case heretofore, notwithstanding the simplifications in its manufacture.

' The foregoing objects, advantages, construction and operation of the present invention will become more readily apparent from the following description and accompanying drawings, in which:

-FIGURE l is a perspective view of an apparatus constructedinaccordance with the present invention; FIGURE 2 is a top view of the apparatus shown in FIGURE 1; I

FIGURE 3 is a side view in partial section taken on line 3-3 of FIGURE 2; and

FIGURE 4 is a view taken on line 4-4 of FIGURE 3, illustrating possible adjustments in the height of the heaters relative to the work surface, thereby to permit The provision of susan fixture 13, taking the form (see FIGURE 3) of a first ring 13a attached to top 11, a second ring 13b attached to the underside of work table 12, interlocking with and slidable in a generally circular path relative to ring 13a, and bearings or the like disposed between said rings 13a and 1312. Various alternative mounting structures may, of course, be used, it being understood that the essential. purpose of the structure employed at 13 is to mount work table or turret 12 upon frame 10 or its top 11 in such manner that said table may be freely rotated in either of two opposing directions, as indicated at 14 (see FIGURE 2), about a substantially central table axis 15; or so that said table may otherwise be relatively freely movable in a variety of directions under the control and at the will of an operator of the equipment.

Table 12 may have various shapes and physical configurations. In the particular form illustrated in the drawings, the table 12 is substantially rectangular in form, with the various corners being obliquely cut as illustrated to provide desired clearances between the table, the edges of frame 10 and its top 11, and the heating recess well and hood to be described. In the alternative, the table 12 may be substantially circular in configuration, mounted upon a central rotational axis, or it may take some other peripheral shape and other form and position of freely movable mount, depending upon the type of article being manufactured and upon the extent of rotation or other movement desired of table 12 during manual manipulation of said article, or of its components, thereon.

Table 12 is fabricated of a continuous sheet of heat conductive material, e.g., a metal such as aluminum. Means are also provided adjacent a preselected portion of table 12 for heating said table 12, by heat conduction, to a substantially uniform preselected temperature throughout. In the preferred embodiment of the invention, said table heating means includes a recessed well 16 supported by frame 10 and extending below the surface of top 11 at a position remote from the front 17 of the overall apparatus; and, more particularly, at a position below table 12 and remote from an operator of the equipment, whereby an operator of the equipment is effectively protected from the heating means by its positioning in the equipment relative to the operator and relative to table 12. In this latter respect, the frame 10 and its front 17 define a normal operator location or station at which a person using the apparatus of the present invention may stand to manipulate materials on freely rotatable Work table 12; and the heating Well 16 is, as illustrated, disposed at a position remote from the front 17 of operators station, and is, in fact, in large part covered by table 12 (see FIGURE 2), thereby to minimize the possibility of an operators engaging the heating apparatus itself.

The recessed well 16 is lined with heat reflective material 18, e.g., polished sheet aluminum, and includes elongated apertured brackets 19 on opposed sides thereof adapted to removably receive hangers 20 attached to a vertically adjustable platform 21. Platform 21 has length and width dimensions substantially equal to the interior dimensions of the recessed heating well 16. Said platform 21 further includes an upper heat reflective surface 22 constructed, for example, of polished sheet aluminum, and supporting two or more electrical heating coils 23 thereon. Heating coils 23 are in turn coupled to a power line 24 via wires 24a and switch members 25 and 25a located at the front of operators station 17 of the apparatus, whereby said heating coils can be selectively energized in various combinations thereby to vary the amount of heat generated within well 16.

Brackets 19 and their cooperating hangers 20 permit platform 21 to be readily changed in position, as illus trated diagrammatically at 21a in FIGURE 4, thereby to alter the spacing between the heating coils 23 and the lower surface of metal work table 12 (see FIGURE 3). The switchmeans -25a, in conjunction with the variable position support for platform 21, accordingly permits a wide range of possible temperatures to be produced in work table 12, with the actual temperature being subject to selection and ready variation as may be desired with changes of ambient temperature and/or changes in the material being manipulated.

As is best illustrated in FIGURES 1, 2 and 3, portions of work table 12 remote from the front of operators station 17 overlie the upper end of heating recess well 16. A hood is provided in this same general area, characterized by an inclined inner reflective surface 31 which extends from a position adjacent the top of recess well 16, past the edge of work table 12, to a location above said work table 12. The inclined nature of reflective surface 31 in relation to the heat source or heating coils 23, and in relation to the horizontal position of table 12, results in a portion of the heat generated within well 16 being reflected and radiated across the upper surface of table 12 at locations spaced above the upper surface of table 12, all as indicated, for example, by arrows 32 in FIGURE 3. This heat reflection and radiation thus assures that the temperature of the space above table 12 is essentially the same as that of the table 12 itself. As a result, materials placed on table 12 tend to hold their temperature even when lifted away from the surface of said table in the course of manipulation. This result is achieved by hood 30 and its inclined surface 31, Withut interfering with the working area provided on table 12 since (see, for .example, FIGURE 3) inclined surface 31 is so positioned relative to table 12 that it does not significantly overlie the upper surface of said table 12.

The overall apparatus is preferably further associated with a wedge 35 attached, e.g., by a chain 36 to the top 11 of frame 10, and adapted to be selectively inserted under an edge of table 12 when it is desired to'restrict, for some reason, rotation thereof. Alternative, and more elaborate if desired, braking or restraining means can be provided. In addition, the apparatus is associated with a known form of trigger-actuated stapling or tacking gun 37, e.g., powered from a sourceof compressed air via a hose 38, whereby an operator standing at station 17 and manipulating articles on table 12 effects permanent fastenings, as desired, by use of the power stapler or tacker 37 v In using the apparatus thus provided, sheet plastic material, e.g., as illustrated at 39, may be placed face-side or pattern-side down on table 12, whereby said sheet material is elevated in temperature to the temperature selected for table 12. A shaped supporting form 40, e.g., of foam rubber or the like mounted, for example, on a wooden base, may thereafter be placed upon the sheet material 39, base-side up. An operator standing at station 17 then folds the sheet material 39. about form 40, pulling it at the corners as may be necessary to assure a tight fit; and permanently fastens the sheet material in place to said form and/or to its base, by means of the power stapler 37.

As a practical matter, the table 12 should be heated to .-a temperature in the order of 180 F. when the sheet plastic material 39 is of known types, having a melting point in the order of 250 F. At this temperature, the sheet plastic material is merely softened without distorting any embossed patterns or the like thereon. As the sheet plastic material is pulled about the form 40 to encapsulate that form, any stretching of the material is distributed throughout the material rather than being confined to local areas thereof only, whereby pattern distortions are eliminated or minimized. In addition, even when the sheet plastic material is lifted away from table 12 for purposes of being folded about form 40, the temperature of the sheet plastic material is nevertheless main- .tended to be illustrative only and not lirnitative of my invention, and all such modifications and variations are meant to fall within the scope of the appended claims.

Having thus described my invention, I claim: 1. Apparatus for heating and manipulating sheet plastic material comprising supporting means having a work table thereon, said work table having a continuous upper surface for supporting a sheet of plastic material, means mounting said table for free rotation in either of two opposing directions about a substantially central table axis, said supporting means including means defining an operator location adjacent a first portion of said rotatable table whereby an operator may stand adjacent said first rotatable table portion to manually manipulate sheet plastic material on said freely rotatable table, said table being comprised of a heat-conductive material, said supporting means including a recessed heat reflective well located below a second portion of said rotatable table at a position remote from said operator location, heating means comprising at least one element mounted within said well at a position below said table whereby all portions of said table are heated from said remote location by radiation from said well to the underside of said table and thence by conduction through said heat-conductive table thereby to heat sheet plastic placed on said upper surface of said table, said heating means including an inclined heat reflective surface extending from an upper portion of said Well across an edge of said table to a position above the upper surface of said table for radiating heat across said rotatable table at locations spaced above the upper surface of said table to maintain said sheet material heated when it is lifted away from said upper surface in the course of manual manipulation by said operator, said inclined heat reflective surface being located across an edge of said table remote from said opera-tor with the uppermost edge of said heat reflective surface being positioned in substantially nonoverlapping relation to the upper surface of said table thereby leaving substantially all of said upper surface freely accessible to an operator as a work area.

2. In an apparatus for manufacturing sheetplastic covered articles, frame means supporting a metallic work table for free bidirectional rota-tion, a first edge portion of said table being located closely adjacent a front portion of said frame means whereby an operator may stand adjacent said front portion of said frame means and adjacent said table to manipulate sheet plastic material and supporting forms therefor on said table, said frame means also defining a heat-refiectively lined heater well positioned below a second edge portion of said table spaced from said first edge portion thereof and remote from said front portion of said frame means, controllable heater means in said well for heating said table to selectively different temperatures there-by to permit heating of said material and forms during manipulation thereof on said table by said operator, and an inclined heat-reflective surface located adjacent said well and extending from a portion of said frame means to a position located above said table for projecting radiant heat energy from said well to positions above said table thereby substantially to main table thereby to permit the temperature of said table to be varied.

4. The apparatus of claim 2 wherein said controllable heater means comprises a plurality of electrical heating coils mounted in said well below said table, and electric switch means for selectively energizing diflerent ones of Said'coils in selectable combinations thereby to vary the temperature of said table.

5. An apparatus for heating plastic articles to a temperature adapted to soften said articles without distorting patterns therein and for maintaining said articles so heated during manual manipulation thereof, comprising a metallic work table, means mounting said table for free rotation in either of two opposing directions about a predetermined table axis, means defining an operator location adjacent a first portion of said table on one side of said axis whereby an operator may stand adjacent said first table portion to manually manipulate articles on said table, heating means including a heating elementlocated below a second portion of said table on an opposite side of said axis at a position remote from said operator location for heating all portions of said rotatable metallic table by radiation from said heating element to the underside of said table and thence by conduction, through said table,

means for selectively varying the vertical position of said heating element to vary the spacing between said element and the underside of said ta-ble' thereby to control-the temperature of said table, and means for radiating heat across the upper surface of said table in directions transverse to said table axis to maintain the temperature of said articles when said articles are lifted away from said upper surface in the course of manual manipulation by said operator, said last-named means being positioned in substantially non-overlapping relation to the upper surface of said table thereby to leave substantially all portions of the upper surface of said table readily accessible to an operator.

References Cited by the Examiner UNITED STATES PATENTS 1,049,488 1/1913 Hughes et al. 219-486 1,726,337 8/1929 Brown 2l9-347- 2,118,116 5/1938 Schweitzer 219-434 2,156,860 5/1939 Lucas et al 219-461 3,095,186 6/1963 Sondy 2637 RICHARD M. WOOD, Primary Examiner.

Claims (1)

1. 5. AN APPARATUS FOR HEATING PLASTIC ARTICLES TO A TEMPERATURE ADAPTED TO SOFTEN SAID ARTICLES WITHOUT DISTORTING PATTERNS THEREIN AND FOR MAINTAING SAID ARTICLES SO HEATED DURING MANUAL MANIPULATION THEREOF, COMPRISING A METALLIC WORK TABLE, MEANS MOUNTING SAID TABLE FOR FREE ROTATION IN EITHER OF TWO OPPOSING DIRECTIONS ABOUT A PREDETERMINED TABLE AXIS, MEANS DEFINING AN OPERATOR LOCATION ADJACENT A FIRST PORTION OF SAID TABLE ON ONE SIDE OF SAID AXIS WHEREBY AN OPERATOR MAY STAND ADJACENT SAID FIRST TABLE PORTION TO MANUALLY MANIPULATE ARTICLES ON SAID TABLE, HEATING MEANS INCLUDING A HEATING ELEMENT LOCATED BELOW A SECOND PORTION OF SAID TABLE ON AN OPPOSITE SIDE OF SAID AXIS AT A POSITION REMOTE FROM SAID OPERATOR LOCATION FOR HEATING ALL PORTIONS OF SAID ROTATABLE METALLIC TABLE BY RADIATION FROM SAID HEATING ELEMENT TO THE UNDERSIDE OF SAID TABLE AND THENCE BY CONDUCTION, THROUGH SAID TABLE, MEANS FOR SELECTIVELY VARYING THE VERTICAL POSITION OF SAID HEATING ELEMENT TO VARY THE SPACING BETWEEN SAID ELEMENT AND THE UNDERSIDE OF SAID TABLE THEREBY TO CONTROL THE TEMPERATURE OF SAID TABLE, AND MEANS FOR RADIATING HEAT ACROSS THE UPPER SURFACE OF SAID TABLE IN DIRECTIONS TRANSVERSE TO SAID TABLE AXIS TO MAINTAIN THE TEMPERATURE OF SAID ARTICLES WHEN SAID ARTICLES ARE LIFTED AWAY FROM SAID UPPER SURFACE IN THE COURSE OF MANUAL MANIPULATION BY SAID OPERATOR, SAID LAST-NAMED MEANS BEING POSITIONED IN SUBSTANTIALLY NON-OVERLAPPING RELATION TO THE UPPER SURFACE OF SAID TABLE THEREBY TO LEAVE SUBSTANTIALLY ALL PORTIONS OF THE UPPER SURFACE OF SAID TABLE READILY ACCESSIBLE TO AN OPEATOR.

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