US 3622433 A
Description (OCR text may contain errors)
United States Patent 1 72] Inventor Edward L. Clark Wellington Drive, Bedford, Va. 24523 [21 1 Appl No. 696,339  Filed Jan. 8, 1968  Patented Nov. 23, 1971  DOUBLE WELT STRIP 5 Claims, 9 Drawing Figs.
52 u.s.c| 161/101, 161/130,161/139,l61/142,l61/145,161/149 511 1111.01 B32b3/04, B32b3/02 501 FieldofSearch 156/200,
Primary Examiner.lohn T. Goolkasian Assistant Examiner-Williard E. Hoag Attorney-Watson, Cole, Grindle & Watson ABSTRACT: A double or single welt for use in the upholstered furniture and other industries, as well as a method and an apparatus for making such welts. The double welt comprises an elongated strip of textile or other material with its longitudinal edges folded or rolled inwardly toward each other to form two tubes, into which cords are preferably introduced, the outer surface of each infolded edge portion engaging the inner surface of the unfolded central portion of the strip and being permanently secured thereto as by adhesive, the cords being free to move longitudinally within the strip material. The single welt may be formed by slitting a double welt made as stated, or by forming a single fold or tube from a narrower strip of material, utilizing essentially the same method of folding or rolling the material upon itself, inserting a cord if desired, and securing the outer surface of the folded material to the inner surface of the unfolded material. An apparatus suitable for performing the stated method comprises a folder mechanism, an adhesive applying means, and means for advancing the material (and cords if used) through said mechanism and past said adhesive applying means.
DOUBLE WELT STRIP BACKGROUND OF THE INVENTION 1. Field of the Invention Double welt is used as a trim to cover the staples or tacks which hold the upholstery material to the wood frame of a piece of upholstered furniture. In some instances the wood frame is grooved, the edge of the upholstery material being fastened in the groove, and in such cases a single welt is inserted in the groove to cover the staples or tacks as well as to assist in holding the upholstery material in place. In either case the welt is customarily glued to the furniture frame. Double or single welts may also be employed for analogous purposes in industries other than the upholstered furniture industry as, for example, the interior decorating, automobile, aircraft, railway vehicle, and similar industries.
2. Description of the Prior Art Double and single welts of the type mentioned above are customarily made of the same fabric as the rest of the upholstery. The conventional double welt is made on a specialized sewing machine, and consists of a strip of fabric which passes through a rather complicated folder and is then sewn while in the folded position. The thread color should be selected to match the fabric. There is a lip or ridge on the bottom of the welt caused by the necessity of a return fold to prevent raveling of the fabric edges. The conventional single welt is also made by folding a strip of fabric, usually containing a cord, and joining the edges of the fabric by sewing, the edges of the fabric of course projecting beyond the line of stitching. In either case there is a rough or uneven surface which must be glued to the wood of the furniture frame. In the case of conventional sewn welts, basting staples or tacks are used for holding the welt to the frame while the glue dries, after which, being in plain view, they must be removed.
SUMMARY OF THE INVENTION According to the present invention there is provided a double welt comprising an elongated strip of material, each longitudinal edge of which is folded inwardly so that the outer surface of each folded portion adjacent its edge engages the opposite or inner surface of the unfolded center portion of the strip, the said outer surfaces being permanently secured, as by an adhesive or other suitable means, to the said inner surface. Such a double welt presents a flat lower surface for gluing to the furniture frame and provides the deepest possible groove or recess between the two welts. This enables the use, if desired, of well-hidden staples in addition to, or in place of, glue for holding the welt to the furniture frame, thus providing a stronger construction. Use of the welt of the present invention eliminates the time-consuming operation of removing the basting staples or tacks. Another advantage of the invention is that it eliminates the necessity of matching a thread to the upholstery material, as is necessary in the manufacture of a sewn welt.
According to the present invention, a single welt of improved type may be obtained by making a double welt as aforesaid and slitting the fabric between the two welts. Alternatively, the single welt may be formed by rolling a narrow strip of material from one edge toward the other, preferably enclosing a cord, after which the outer surface of the folded or rolled edge is secured to the inner or upper surface of the other edge as by adhesive.
The invention also includes the provision of a method of forming a double or single welt of the type described. The method of forming the double welt comprises the steps of folding an elongated strip of material inwardly from each longitudinal edge thereof to being the outer surface of each folded portion, adjacent the respective edge of said material, into close proximity to the inner surface of the unfolded material between such folded portions, and securing the said edge adjacent outer surfaces to the said inner surface, as by means of a suitable adhesive material. Preferably a cord is enclosed within each of the folded edge portions during the folding process. The cords, not being adhered to the textile material, are free to move longitudinally within the latter, thus allowing better accommodation of the welt to curves and bends, without puckering or buckling.
The method of the present invention eliminates the need for special purpose sewing machines with the attendant problems of thread breakage, bobbin changes, etc. The double welt of the invention possesses the'advantage of an improved appearance because of the deepest possible groove between the cords, which groove is narrow and uniform. A second advantage is that it provides a flat base with no folded undersurface or other projections to prevent smooth application of the welt to the furniture frame. If glue is used to hold the welt to the furniture, there is a smooth gluing surface. Also, as mentioned above, mechanical fasteners such as staples may be used, with or without adhesives, to hold the welt to the furniture, and such fasteners would be completely hidden in the deep groove. The use and subsequent removal of basting fasteners is completely eliminated. It is estimated that the improved welt of the present invention can be applied to the furniture at least 25 percent faster than the conventional welt, not counting the additional time saved by eliminating the necessity for removal of basting fasteners.
The invention further includes the provision of a suitable apparatus for carrying out the novel method mentioned above. Such apparatus includes a folder mechanism, an adhesive-applying means, and a material-advancing means for causing the textile material and the cords, if used, to pass through the folder mechanism and past the adhesive-applying means. The folder mechanism includes a troughlike passage for strip material which passage at its entering end has a relatively wide bottom and narrow sidewalls, the bottom portion adjacent each sidewall being inclined upwardly and outwardly at a slight angle which increases progressively with the distance from the entering end, so that the said inclined portions gradually turn inwardly toward each other and then downwardly toward the center of said bottom portion, the central portion of which narrows progressively with the distance from the entering end. This progressive inward and downward turning of the lateral edges of the trough bottom results in the formation of substantially separate passageways for progressively infolding the respective edges of the strip material. Preferably the folder mechanism includes a pair of tubes for the introduction of cords, each tube extending from a point near the entering end of the folder mechanism to a point within one of the said separate passageways, so that a cord is enclosed within each of the infolded edges of the strip material as the folding step approaches completion. The folder mechanism also includes means for tucking the infolded edges of the material under the cords and adhesive-applying means including nozzle means extending into the mechanism midway transversely thereof and near the exits from the said separate passageways, which nozzle means is provided with lateral orifices for extruding adhesive material onto and between the outer surface of each infolded edge portion and the upper or inner surface of the unfolded central portion of the strip material. Lastly, the folder mechanism includes means for pressing the adhesive bearing surfaces together as the material completes its travel through the mechanism. If a low-profile welt is desired, with no exposed edges, the welt cords can be eliminated, in which case the above-mentioned tubes are not used.
The adhesive may be applied as described above, or, alternatively, the adhesive may be applied to the outer surface of each infolded portion during the folding process, or to suitable areas of the fabric prior to its entry into the folder mechanism. In the latter case, the adhesive may be in solid or dry ribbon or filamentary form and fed into the folder mechanism with the strip material, to be activated by heat or otherwise after the folding is completed. In the case of vinyls and other plastic materials, adhesion may be accomplished by self welding or reactivation of the material by various means. In the case of the apparatus to be described below, the adhesive to be employed is preferably of the hot melt variety, and the apparatus includes means for maintaining a supply of such adhesive at an elevated temperature, together with means for feeding a stream of adhesive material, at a somewhat higher temperature and under pressure, to the above-mentioned nozzle means. i
The means for advancing the material through the folder mechanism preferably comprises a rotary member presenting a cylindrical surface adjacent the exit end of the folder mechanism, which cylindrical surface is covered with a material of strong frictional characteristics, for gripping the undersurface of the welt issuing from the folder mechanism, the rotary member being driven from a suitable power source. The required frictional characteristic may be conveniently provided by covering the cylindrical surface of the rotary member with the well-known card cloth" used in the textile industry for carding fibrous material.
The provision of the welts, methods, and apparatus mentioned above are among the objects of the present invention. Other and further objects, features and advantages will appear from the description of the preferred embodiments as set forth below.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an apparatus according to the present invention;
FIG. la is a perspective view of a piece of double welt made in accordance with the invention;
FIG. 2 is a plan view of the folder mechanism of said apparatus, with the material and cords of the welt being shown in phantom;
FIGS. 3 and 4 are transverse sections on lines 3-3 and 4 4, respectively, of FIG. 2;
FIG. 5 is an end view of the double welt of FIG. 1a; FIG. 6 is a fragmentary vertical section on line 6-6 of FIG. 1;
FIG. 7 is a vertical section illustrating an alternative form of material advancing means; and
FIG. 8 is a perspective view of the power transmission for the adhesive pump and the material advancing means of the device illustrated in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 of the drawings illustrates, in perspective, the preferred embodiment of the apparatus for carrying out the method and producing the article of the present invention. For convenience and safety, the moving parts of the apparatus are enclosed, so far as possible, within a casing 10, the enclosed parts being illustrated in FIG. 8 and described hereinafter. A motor 11, supported externally of the casing 10 provides the small amount of power necessary for driving the moving parts of the device. A folder mechanism 12 is supported by any suitable means outside the casing 10, such support being provided, in the present instance, by a rod 13 mounted in a block 14 secured to the casing 10, the folder l2 being slidably supported on the rod 13 by means ofa screw clamp 15.
A gluepot I6 is mounted upon a glue pump 17 which in turn is supported by the top wall of the casing 10, a suitable thickness of heat-insulating material 18 being interposed between the pump 17 and the casing 10. One end of the pump 17 projects outwardly beyond the sidewall of the casing 10 and carries, at its outer end, a glue distributor 19 which in turn carries, at its lower end, a nozzle 20. The outer end of the pump 17 and associated parts are supported by a bracket 21 secured to the adjacent wall of the casing 10.
A ring-type electric heater 22 for the gluepot 16 is interposed between the bottom of the latter and the top of the pump 17, and is energized from any suitable source of electricity, the temperature of the adhesive material within the pot 16 being maintained constant through the use of a thermostat 23 controlling the energy supplied to the heater element 22. In
the present instance the hot melt adhesive employed is maintained at a temperature between 250 and 300 F., depending on the formulation of the adhesive, at which temperature it is in a fluid but viscous state.
As best seen in FIG. 6, the centrally disposed threaded stud 24 by means of which the pot 16 is secured to the pump 17 is centrally bored to provide a conduit 25 connecting the interior of the pot 16 with a longitudinal cavity 26 formed in the pump 17. The cavity 26 is similarly connected through conduits 27 and 28 with the glue distributor 19, which is bored to provide a portion of the conduit 28 and a connecting conduit 29 leading to the nozzle 20. The glue distributor 19 is provided with a rod-type electric heating element 30 controlled by a thermostat 31 to maintain the adhesive passing to the nozzle 20 at a temperature somewhat above the temperature maintained in the pot 16, whereby the adhesive issuing from the nozzle 20 is sufficiently fluid to be distributed easily and evenly upon the surfaces to be adhered together. The nozzle 20 is provided with a central longitudinal conduit 32 connecting at its lower end with oppositely disposed lateral orifices 33, 33a.
Disposed within the longitudinal cavity 26 of the pump 17 is a screw-threaded pump member 34 which is driven in rotation by the motor 11 through a gear transmission 35, sprocket 36, chain 37, sprocket 38 on driven shaft 39, sprocket 40 on the same shaft, chain 41, sprocket 42 on countershaft 43, sprocket 44 on the latter shaft, chain 45 and sprocket 46 fixed on the outer end of the threaded member 34. The lands and grooves of the threaded portion of the member 34 are so proportioned, progressively, as to exert a somewhat higher pressure upon the advancing adhesive as it approaches the discharge end of the member 34 and enters the conduit 27, thus imparting the necessary pressure to extrude the adhesive at the desired rate through the orifices 33, 33a. The desired speed of rotation of the member 34 and resulting pressure upon the advancing adhesive may, of course, be achieved through any suitable means alternative to the gear transmission and sprocket chain drive illustrated and described.
Referring now to FIG. 2 of the drawing the folder mechanism 12 may be described as troughlike in form, and having a transverse section which narrows progressively to the point at which the folding step is completed, just in advance of the point at which the adhesive material is applied. The entering end of the folder mechanism is preferably formed with a downturned lip 48 and a bottom portion 49 which is substantially flat at its juncture with the lip 48. The entering end of the bottom portion 49 is flanked by narrow sidewalls 50 and 51, the folder mechanism, at this point, being open at the top. Immediately beyond the juncture of the bottom portion 49 with the lip 48, the respective lateral edge portions 52 and 53 of the bottom portion 49 are angled upwardly at a slight inclination, which inclination increases progressively with the distance from the entering end, the inclined portions 52 and 53 gradually turning inwardly toward each other and then downwardly toward said bottom 49, the central portion of which narrows progressively with the distance from said entering end. Thus, the folder mechanism gradually progresses, in transverse section, from a flat trough for the admission of the strip material 47 into two substantially separate passageways for progressively infolding the respective edges of the strip material as seen in FIG. 4, this progression being illustrated at an intermediate stage in FIG. 3. Beginning at a point slightly beyond the entering end, the folder mechanism is provided with two tubes 54 and 55 through which cords 56 and 57 are introduced. The tubes 54 and 55 terminate within the aforesaid substantially separate passageways, at a point slightly in advance of the section line 4-4 of FIG. 2, at which point the cords are completely enclosed within the infolded edge portions of the strip material 47 as seen in FIG. 4. Between the tubes 54 and 55, there is provided a tongue 58 which is secured to said tubes at its rear or left end, but is free spring to maintain the central portion of the strip material 47 against the bottom 49 as the material advances through the folder mechanism.
As will be seen in FIG. 4, the downturned edges of the inclined portions 52 and 53 are joined, at a point just in advance of the section line 4 of FIG. 2, to form a short central partition separating the aforesaid substantially separate passageways for the respective infolded edges of the strip material, each enclosing a cord. From this point onward, the downturned portions 52 and 53 are discontinued, the remaining length of the folder mechanism comprising a bottom portion 49 which progressively narrows to a slight degree, and upwardly and inwardly extending sidewalls 52' and 53. The latter may be spaced apart at their upper extremities and their edges may be recessed as at 59 if necessary to accommodate the entry therebetween of the nozzle 20 of the adhesive-applying means. If desired the bottom portion 49 may be apertured as at 60 beneath the noule 20 to facilitate determination of the proper adjustment of the folder mechanism relative to the nozzle. The converging form of the folder mechanism beyond this point serves to maintain in close engagement the surfaces to which adhesive has been applied through the nozzle 20, for the short duration of time necessary to enable the adhesive to set firmly.
Just beyond the exit end of the folder mechanism 12 the welt which has now been fully formed is gripped by the material-advancing means comprising a narrow roller 61 secured to a projecting end of the shaft 39 which is driven as described above. The roller 61 may be of any suitable construction and preferably presents a cylindrical surface 62 flanked by projecting annular portions of sideplates 63 and 64. The surface 62 is formed of the well-known card cloth provided with projecting wires or bristles which are inclined forwardly and outwardly so as to frictionally engage the underside of the welt as it leaves the folder mechanism 12. In order to strip the welt from the surface 62, to which it would otherwise cling, a stripper 65 is provided, in the form of a slotted plate through which the upper portion of the roller 61 projects. The slot 66 is provided with one or more wires 67 which serve to strip the advancing welt from the surface 62 after a short travel thereon, during which rotation of the roller 61 provides the necessary traction to draw the strip material and cords into and through the folder mechanism 12.
A preferred form of the material advancing means is illustrated in FIG. 7 in which the roller 61 comprises a hub 68 secured on the shaft 39 and a disc 69 integral with the hub 68 and having a peripheral flange 70. The latter carries a ring of resilient material 71, for example, of rubber, which is slightly wider than the flange 70, and the outer surface of which carries the aforesaid card cloth surface 62. In the case of the embodiment of FIG. 7, the sideplates 63' and 64 are loosely mounted on the shaft 39, being retained by collars 72 and 73 secured to the shaft 39 by set screws. The collars 72 and 73 are preferably provided with partispherical facing surfaces, to permit angular movements of the plates 63' and 64.
Means are provided adjacent the upper portion of the roller 61 for pressing the plates 63, 64' toward each other so that their outer edges will grip and confine the respective sides of the welt as it issues from the folder mechanism. Such means may consist of spring pressed rollers 75, 75, supported in any suitable manner, which serve to urge the peripheral portions of side plates 63', 64' toward each other at the top of their travel. Rotation of the loosely mounted plates is brought about through their fictional engagement with the lateral edges of the layer 71 of resilient material carried by the flange of the disc 69.
I claimr 1. A double welt comprising an elongated strip of material, said material being bent about two spaced parallel axes, said axes being parallel to the longitudinal cells, the longitudinal edges of said material being disposed in contact with a major surface of an unbent portion of said strip, and a narrow edge portion of the major surface, of said material, forming the exterior of said welt being adjacent with, and being bonded to,
the opposite surface of an unbent portion of said material.
2. A welt according to claim 1 wherein said narrow longitudinal portion of said major surface of said bent material adjacent each of said edges are bonded by means of an adhesive material to said unbent portion major surface.
3. A double welt according to claim 1, said unbent portion and said bent material being so dimensioned that mutually facing surfaces of said longitudinal cells lie in close proximity to each other to provide a narrow groove therebetween.
4. A welt according to claim 1, including a cord enclosed within each said longitudinal cell.
5. A welt according to claim 4, each of said cords being free to move longitudinally within their respective cells.