LAMINATED SHOULDER STRAP
United States Patent 3616148
A shoulder strap material for articles of feminine wearing apparel has an outer shell or envelope of nylon tricot fabric enclosing a cotton fabric tape to which such shell or envelope is bonded by a hot melt or thermoplastic. In the apparatus for producing such strap material, folded side portions of a nylon tricot fabric tape which constitutes the shell or envelope are urged laterally toward each other to close a longitudinal medial seam of the strap material before the bonding is completed by passage through a set of nip or pressure rollers.
US Patent References:
Gasket
Hubbard - November 1932 - 1889144
Decorative material
Prindle - July 1938 - 2124210
Shelf edging
Karfiol - December 1938 - 2141606
Ribbon
Hyman - June 1940 - 2203822
Anticurl device for collars
Liebowitz - June 1952 - 2601038
Gasket
Hubbard - November 1932 - 1889144
Decorative material
Prindle - July 1938 - 2124210
Shelf edging
Karfiol - December 1938 - 2141606
Ribbon
Hyman - June 1940 - 2203822
Anticurl device for collars
Liebowitz - June 1952 - 2601038
Application Number:
05/047984
Publication Date:
10/26/1971
Filing Date:
06/22/1970
View Patent Images:
Export Citation:
Assignee:
Maidrite Novelty Corp. (Long Island City, NY)
Primary Class:
Other Classes:
2/338, 156/467, 450/86
International Classes:
A41F15/00; A41F15/00; B32B3/02
Field of Search:
2/336,338 161/74,86,92,89,99,100,102,103,104,105,106,107,108 128/510
US Patent References:
Primary Examiner:
Burnett, Robert F.
Assistant Examiner:
Linker Jr., Raymond O.
Claims:
What is claimed is
1. A laminated shoulder strap material for articles of feminine wearing apparel comprising a nylon tricot fabric tape having a central portion defining one face of the strap material, side portions folded over said central portion and coming together to define the other face of the strap material with a longitudinal medial seam along said other face and folded-under longitudinal edge portions extending from said seam under said folded over side portions, a cotton fabric tape having a central portion overlying said central portion of the nylon tricot fabric tape and folded side portions extending under said folded over side portions of said nylon tricot fabric tape and projecting between the latter and said folded-under longitudinal edge portions, and thermoplastic material interposed between said central portion of the cotton fabric tape and at least said folded-under longitudinal edge portions of the nylon tricot tape and there bonding together said nylon tricot and cotton tapes.
2. A laminated shoulder strap material according to claim 1, in which said thermoplastic material is in the form of a web substantially coextensive laterally with said central portion of the cotton tape, and said folded-under longitudinal edge portions of the nylon tricot tape are of substantially smaller width than said side portions of the nylon tricot tape so that said web of thermoplastic material also bonds said central portion of the cotton tape to said folded side portions of the latter at the regions of said side portions of the cotton tape which are located laterally outward with respect to said folded-under longitudinal edge portions of the nylon tricot tape.
3. A laminated shoulder strap material according to claim 1, in which said cotton fabric tape has at least one flannel surface to provide the strap with a plump, cushioned appearance.
4. A laminated shoulder strap material according to claim 1, in which said thermoplastic material consists of an open, randomly reticulate mat of thermoplastic filaments.
1. A laminated shoulder strap material for articles of feminine wearing apparel comprising a nylon tricot fabric tape having a central portion defining one face of the strap material, side portions folded over said central portion and coming together to define the other face of the strap material with a longitudinal medial seam along said other face and folded-under longitudinal edge portions extending from said seam under said folded over side portions, a cotton fabric tape having a central portion overlying said central portion of the nylon tricot fabric tape and folded side portions extending under said folded over side portions of said nylon tricot fabric tape and projecting between the latter and said folded-under longitudinal edge portions, and thermoplastic material interposed between said central portion of the cotton fabric tape and at least said folded-under longitudinal edge portions of the nylon tricot tape and there bonding together said nylon tricot and cotton tapes.
2. A laminated shoulder strap material according to claim 1, in which said thermoplastic material is in the form of a web substantially coextensive laterally with said central portion of the cotton tape, and said folded-under longitudinal edge portions of the nylon tricot tape are of substantially smaller width than said side portions of the nylon tricot tape so that said web of thermoplastic material also bonds said central portion of the cotton tape to said folded side portions of the latter at the regions of said side portions of the cotton tape which are located laterally outward with respect to said folded-under longitudinal edge portions of the nylon tricot tape.
3. A laminated shoulder strap material according to claim 1, in which said cotton fabric tape has at least one flannel surface to provide the strap with a plump, cushioned appearance.
4. A laminated shoulder strap material according to claim 1, in which said thermoplastic material consists of an open, randomly reticulate mat of thermoplastic filaments.
Description:
This invention relates generally to shoulder straps for brassieres, slips or other articles of feminine wearing apparel.
Many articles of feminine wearing apparel, such as brassieres, slips, nightgowns and the like, are presently formed of nylon tricot textile fabric. Although the aesthetic desirability of providing such articles of wearing apparel with shoulder straps of the same nylon tricot fabric has long been apparent, previous attempts to produce such shoulder straps have encountered functional inadequacies. More specifically, by reason of the stretch or give inherent in nylon tricot fabrics, straps formed thereof have been undesirably stretchable in the longitudinal direction with such longitudinal stretching being accompanied by lateral narrowing of the strap and consequent discomfort to the wearer by reason of the reduced area of contact of the strap with the shoulder.
Accordingly, it is an object of this invention to provide a shoulder strap of nylon tricot fabric which resists undue longitudinal stretching and consequent lateral narrowing of the strap.
Another object is to provide a laminated shoulder strap which has an outer shell or envelope of nylon tricot fabric enclosing a cotton fabric tape to which the shell or envelope is bonded so that although the strap has the exterior appearance of the nylon tricot fabric, its resistance to longitudinal stretching and lateral narrowing is adequate by reason of the enclosed cotton fabric tape.
A further object is to provide a laminated shoulder strap of the described type which has a plump or cushioned feel and appearance.
Still another object of this invention is to provide an apparatus for manufacturing a laminated shoulder strap of the described character, and which ensures that the produced strap will be of uniform appearance and quality, notwithstanding the stretchability or give of the nylon tricot fabric which has previously presented problems in the manufacture of nylon tricot straps.
In accordance with a feature of this invention, a laminated shoulder strap for articles of feminine wearing apparel comprises a nylon tricot fabric tape having a central portion defining one face of the strap, side portions folded over such central portion and coming together to define the other face of the strap with a longitudinal medial seam along such other face and folded-under longitudinal edge portions extending from the seam under the folded over side portions of the tape, a cotton fabric tape having a central portion overlying the central portion of the nylon tricot tape and folded side portions extending under the folded over side portions of the nylon tricot tape and projecting between the latter and the folded-under longitudinal edge portions, and a web of thermoplastic material, preferably consisting of an open, randomly reticulate mat of thermoplastic filaments, interposed between the central portion of the cotton tape and at least the folded-under longitudinal edge portions of the nylon tricot tape for there bonding together the nylon tricot and cotton tapes.
In accordance with another feature of this invention, the apparatus for manufacturing the described laminated shoulder strap includes an assembly by which the folded over side portions of the nylon tricot tape are urged laterally toward each other to close the longitudinal medial seam of the strap before the bonding together of the nylon tricot and cotton tapes is completed by passage through a set of nip or pressure rolls.
The above and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment which is to be read in connection with the accompanying drawings, wherein:
FIG. 1 is a fragmentary, enlarged plan view showing the several components of a shoulder strap according to this invention prior to the folding and bonding together of such components;
FIG. 2 is a fragmentary plan view of the completed shoulder strap as viewed from the side thereof having the longitudinal medial seam;
FIG. 3 is an enlarged, lateral sectional view taken along the line 3--3 on FIG. 2;
FIG. 4 is a diagrammatic side elevational view illustrating an apparatus by which laminated shoulder straps may be produced in accordance with the present invention;
FIG. 5 is an enlarged top plan view of an assembly included in the apparatus of FIG. 4 for ensuring proper closing of the longitudinal medial seam of the laminated strap;
FIG. 6 is a sectional view taken along the line 6--6 on FIG. 5; and
FIG. 7 is a plan view of the undersurface of a pressing member included in the assembly of FIGS. 5 and 6.
Referring to the drawings in detail and initially to FIG. 1 thereof, it will be seen that a shoulder strap material embodying the present invention and generally identified by the reference numeral 10 on FIGS. 2 and 3 is laminated from a nylon tricot fabric tape 11, a cotton fabric tape 12 having a width smaller than that of the nylon tricot tape 11, and a web 13 having a width smaller than that of the tape 12 and which is formed of a material capable of bonding together the tapes 11 and 12 when subjected to heat and pressure.
Preferably, the web 13, as illustrated on FIG. 1, consists of an open, randomly reticulate mat of thermoplastic polyester filaments, for example, as is available commercially under the tradename "Thermogrip" form USM Corporation, Middleton, Mass. The cotton fabric tape 12 preferably has a flannel or brushed finish on at least one surface thereof, and is arranged so that such flannel surface faces toward the nylon tricot tape 11.
In producing the laminated strap material 10 of FIGS. 2 and 3 from the tapes 11 and 12 and web 13 of FIG. 1, side portions 11a and 12a of tapes 11 and 12, respectively, are folded about fold lines 14 relative to the respective central portions 11b and 12b on which web 13 is superposed, with the opposite longitudinal edge portions 11c of tape 11 being folded under about fold lines 15 which extend along the longitudinal edges of tape 12. It will be apparent that, upon such folding tapes 11 and 12, the nylon tricot fabric of tape 11 forms an outer shell or envelope enclosing cotton tape 12 and thermoplastic web 13, with central portion 11b of tape 11 defining one face of the strap material 10, and with the folded over side portions 11a of tape 11 coming together to define the other face of the strap material having a longitudinal medial seam 16 extending therealong. The folded under longitudinal edge portions 11c of tape 11 avoid the presence of raw edges of fabric at the medial seam 16. It will further be seen that the folded side portions 12a of cotton tape 12 extend under the folded over side portions 11a of the nylon tricot tape and project between such side portions 11a and the folded-under longitudinal edge portions 11c. Preferably, as shown, the folded-under longitudinal edge portions 11c are of substantially smaller width than the folded over side portions 11a of tape 11 so that the opposite side portions of web 13 are interposed between central portion 12b of cotton tape 12 and the folded side portions 12a of such tape at the regions thereof which are located laterally outward with respect to the folded-under longitudinal edge portions 11c of tape 11.
After tapes 11 and 12 have been folded about thermoplastic web 13 in a manner described above, the folded assembly is suitably heated so as to render molten or at least plastic the thermoplastic material of web 13, whereupon the strap material may be passed between pressure rollers which compress together the several fabric layers so as to cause impregnation of the hot melt or thermoplastic material into the fibers of cotton tape 12 and also into the folded-under longitudinal edge portions 11c of nylon tricot tape 11. Thereafter, the strap material 10 is suitably cooled so as to set the hot melt or thermoplastic material employed for bonding together of tapes 11 and 12.
It is an important feature of this invention that, in the completed strap material 10, the hot melt or thermoplastic material of web 13 does not come in contact with, and therefore does not impregnate either the central portion 11b or the folded side portions 11a of the nylon tricot tape 11 which form the outer shell of the strap material, so that the feel or hand of the nylon tricot shell is not affected by the hot melt or thermoplastic material. Nevertheless, by reason of the bonding of the folded-under longitudinal edge portions 11c of tape 11 to the central portion 12b of cotton tape 12 and the fact that the folded side portions 12a and the central portion 12b of cotton tape 12 underlie and are coextensive with the folded side portions 11a and the central portion 11b of the nylon tricot tape 11 constituting the outer shell of the strap material, the cotton tape ensures that the completed strap material will have the necessary resistance to longitudinal stretching and further will resist lateral narrowing or bunching. When cotton tape 12 has a flannel or brushed finish on at least one of its surfaces, as is preferred, the completed strap material 10 will have a plump or cushioned feel and appearance.
In the above description of the strap material 10 according to this invention, the hot melt or thermoplastic material for bonding the tapes 11 and 12 has been furnished in the form of a web composed of the thermoplastic material in the solid state, and which is heated to the molten condition following the folding of tapes 11 and 12. However, if desired, the hot melt or thermoplastic material may be applied, in molten condition, to the central portion of tape 12 prior to the folding operations.
Referring now to FIG. 4, it will be seen that a preferred apparatus 100 for producing the shoulder strap material 10 described above with reference to FIGS. 2 and 3 comprises suitable supported supply rolls 111, 112 and 113 from which tapes 11 and 12 and web 13, respectively, are simultaneously drawn. Web 13 is superposed centrally on tape 12 which is, in turn, superposed centrally on tape 11, as shown on FIG. 1. The assembled tapes 11 and 12 and web 13 are passed under a guide roller 114 and then through a conventional folding device 115 which continuously operates to fold the longitudinal edge portions 11c of tape 11 onto the adjacent edge portions of tape 12. From folding device 115, tapes 11 and 12 and web 13 pass through a further conventional folding device 116 which continuously operates to fold side portions 11a and 12a of tapes 11 and 12 upwardly and inwardly over web 13, that is, to complete the necessary folding operations. Of course, the folding devices 115 and 116 which are shown separate from each other may be combined in a single conventional folding unit.
After tapes 11 and 12 have been folded around web 13, the resulting assembly passes continuously through a suitable heating unit 117 which, as shown, includes confronting upper and lower conductive blocks 118 and 119 defining a shallow, longitudinally extending groove (not shown) between their confronting surfaces and through which the folded assembly of tapes 11 and 12 and thermoplastic web 13 is guided during the heating thereof. The conductive or metal blocks 118 and 119 contain conventional electric heating elements 120 and 121 supplied with electric current through suitable thermostatically regulated circuits (not shown). Preferably, such circuits are controlled so that the upper heating elements 120 will heat the upper surface of the folded assembly to a temperature that is slightly higher than that to which the lower surface of the folded assembly is heated by the lower heating elements 121. For example, when using the specific material identified above for the thermoplastic web 13, it is desirable to control the heating elements 120 and 121 so that the top surface of the folded assembly will be heated to no more than 320° F., while the lower surface of the folded assembly is heated to no more than 300° F.
After web 13 has been rendered molten or at least plastic by the heating thereof in unit 117, the strap material is passed through the nip 122 between pressure rollers 123 which are suitably driven, as by a motor 124. It will be apparent that the driven rollers 123 constitute at least part of the drive by which tapes 11 and 12 and web 13 are withdrawn from the respective drive rolls, and then passed through folding devices 115 and 116 and heating unit 117. The inherent drag or resistance to movement of the tapes 11 and 12 and web 13, particularly through folding devices 115 and 116, gives rise to a substantial tension which, in the case of the nylon tricot tape 11, tends to longitudinally extend the tape and thereby laterally narrow the tape. Such lateral narrowing of nylon tricot tape 11 after passage through folding device 116 tends to open or create a gap at seam 16, and this tendency has constituted a major obstacle to the production of a satisfactory laminated nylon tricot strap material. However, in accordance with the present invention, the apparatus 100 further comprises a device 125 located between heating unit 117 and pressure rollers 123, and preferably relatively close to the latter, which device 125 acts on the folded-over side portions 11a of tape 11 to urge such portions 11a laterally toward each other in response to the movement of the strap material by rollers 123, whereby to ensure that seam 16 is tightly closed upon passage through the nip 122 between rollers 123.
Referring now to FIGS. 5 and 6, it will be seen that the device 125 comprises a horizontal base plate 126 mounted, as by a bracket 127 (FIG. 4) on the frame 128 supporting pressure rollers 123. Base plate 126 is formed, in its upper surface, with a longitudinal, upwardly opening groove or channel 129 which is laterally dimensioned to guide the folded strap material and which has its bottom surface at the level of nip 122. A pressing member 130 is urged downwardly in channel 129 to bear upon the folded overside portions 11a of tape 11 and has a V-shaped notch 131 in its end portion which is first encountered by the strap material during its movement through channel 129 in the direction of arrow 132 on FIG. 5. The notch 131 opens at least at the bottom surface 133 (FIG. 7) of member 130 and may extend through the entire thickness thereof, as shown. The sides 134 of notch 131 converge in the direction of travel 132 of the strap material and enclose an angle a (FIG. 5) that is no greater than 60°. Preferably, such angle a is substantially smaller than 60°. Further, the apex of notch 131 in bottom surface 133 is preferably rounded and tapered into surface 133, as at 135 on FIGS. 6 and 7.
In order to retain member 130 in channel 129, the top surface 136 of member 130 projects upwardly from channel 129 and has a step 137 (FIG. 6) facing in the direction of movement 132 of the strap material. A loading member 138 extends across channel 129 and rests on top surface 136 so as to be engaged by step 137. The opposite end portions of member 138 have holes (not shown) which loosely receive bolts 139 screwed into tapped holes provided in base plate 126, and compression springs 140 are provided on bolts 139 between the heads of the latter and member 138 to urge the latter downwardly. Obviously, the forces exerted by springs 140 can be readily varied by adjustment of bolts 139.
With the device 125 as described, movement of the strap material through channel 129 in response to the rotation of pressure rollers 123 draws folded side portions 11a of tape 11 under pressure member 130 while the latter is urged downwardly by springs 140. Due to the notch 131, the lower surface 133 of member 130 exerts an inwardly directed force on each folded side portion 11a to tightly close the seam 16. The rounded and tapered apex 135 of notch 131 ensures that the fabric of tape 11 will not pucker as it is drawn under pressing member 130.
With its seam 16 thus tightly and uniformly closed, the strap material passes through pressure rollers 123 by which the fabric layers are compressed together and the molten or at least plastic material of web 13 is made to impregnate the confronting fabric layers. After passage between rollers 123, the strap material may be guided by a roller 141 and by other similar rollers (not shown) to follow a sinuous path along which the strap material is suitably cooled.
Although particular embodiments of strap material according to this invention and of an apparatus for producing the same have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of this invention.
Many articles of feminine wearing apparel, such as brassieres, slips, nightgowns and the like, are presently formed of nylon tricot textile fabric. Although the aesthetic desirability of providing such articles of wearing apparel with shoulder straps of the same nylon tricot fabric has long been apparent, previous attempts to produce such shoulder straps have encountered functional inadequacies. More specifically, by reason of the stretch or give inherent in nylon tricot fabrics, straps formed thereof have been undesirably stretchable in the longitudinal direction with such longitudinal stretching being accompanied by lateral narrowing of the strap and consequent discomfort to the wearer by reason of the reduced area of contact of the strap with the shoulder.
Accordingly, it is an object of this invention to provide a shoulder strap of nylon tricot fabric which resists undue longitudinal stretching and consequent lateral narrowing of the strap.
Another object is to provide a laminated shoulder strap which has an outer shell or envelope of nylon tricot fabric enclosing a cotton fabric tape to which the shell or envelope is bonded so that although the strap has the exterior appearance of the nylon tricot fabric, its resistance to longitudinal stretching and lateral narrowing is adequate by reason of the enclosed cotton fabric tape.
A further object is to provide a laminated shoulder strap of the described type which has a plump or cushioned feel and appearance.
Still another object of this invention is to provide an apparatus for manufacturing a laminated shoulder strap of the described character, and which ensures that the produced strap will be of uniform appearance and quality, notwithstanding the stretchability or give of the nylon tricot fabric which has previously presented problems in the manufacture of nylon tricot straps.
In accordance with a feature of this invention, a laminated shoulder strap for articles of feminine wearing apparel comprises a nylon tricot fabric tape having a central portion defining one face of the strap, side portions folded over such central portion and coming together to define the other face of the strap with a longitudinal medial seam along such other face and folded-under longitudinal edge portions extending from the seam under the folded over side portions of the tape, a cotton fabric tape having a central portion overlying the central portion of the nylon tricot tape and folded side portions extending under the folded over side portions of the nylon tricot tape and projecting between the latter and the folded-under longitudinal edge portions, and a web of thermoplastic material, preferably consisting of an open, randomly reticulate mat of thermoplastic filaments, interposed between the central portion of the cotton tape and at least the folded-under longitudinal edge portions of the nylon tricot tape for there bonding together the nylon tricot and cotton tapes.
In accordance with another feature of this invention, the apparatus for manufacturing the described laminated shoulder strap includes an assembly by which the folded over side portions of the nylon tricot tape are urged laterally toward each other to close the longitudinal medial seam of the strap before the bonding together of the nylon tricot and cotton tapes is completed by passage through a set of nip or pressure rolls.
The above and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment which is to be read in connection with the accompanying drawings, wherein:
FIG. 1 is a fragmentary, enlarged plan view showing the several components of a shoulder strap according to this invention prior to the folding and bonding together of such components;
FIG. 2 is a fragmentary plan view of the completed shoulder strap as viewed from the side thereof having the longitudinal medial seam;
FIG. 3 is an enlarged, lateral sectional view taken along the line 3--3 on FIG. 2;
FIG. 4 is a diagrammatic side elevational view illustrating an apparatus by which laminated shoulder straps may be produced in accordance with the present invention;
FIG. 5 is an enlarged top plan view of an assembly included in the apparatus of FIG. 4 for ensuring proper closing of the longitudinal medial seam of the laminated strap;
FIG. 6 is a sectional view taken along the line 6--6 on FIG. 5; and
FIG. 7 is a plan view of the undersurface of a pressing member included in the assembly of FIGS. 5 and 6.
Referring to the drawings in detail and initially to FIG. 1 thereof, it will be seen that a shoulder strap material embodying the present invention and generally identified by the reference numeral 10 on FIGS. 2 and 3 is laminated from a nylon tricot fabric tape 11, a cotton fabric tape 12 having a width smaller than that of the nylon tricot tape 11, and a web 13 having a width smaller than that of the tape 12 and which is formed of a material capable of bonding together the tapes 11 and 12 when subjected to heat and pressure.
Preferably, the web 13, as illustrated on FIG. 1, consists of an open, randomly reticulate mat of thermoplastic polyester filaments, for example, as is available commercially under the tradename "Thermogrip" form USM Corporation, Middleton, Mass. The cotton fabric tape 12 preferably has a flannel or brushed finish on at least one surface thereof, and is arranged so that such flannel surface faces toward the nylon tricot tape 11.
In producing the laminated strap material 10 of FIGS. 2 and 3 from the tapes 11 and 12 and web 13 of FIG. 1, side portions 11a and 12a of tapes 11 and 12, respectively, are folded about fold lines 14 relative to the respective central portions 11b and 12b on which web 13 is superposed, with the opposite longitudinal edge portions 11c of tape 11 being folded under about fold lines 15 which extend along the longitudinal edges of tape 12. It will be apparent that, upon such folding tapes 11 and 12, the nylon tricot fabric of tape 11 forms an outer shell or envelope enclosing cotton tape 12 and thermoplastic web 13, with central portion 11b of tape 11 defining one face of the strap material 10, and with the folded over side portions 11a of tape 11 coming together to define the other face of the strap material having a longitudinal medial seam 16 extending therealong. The folded under longitudinal edge portions 11c of tape 11 avoid the presence of raw edges of fabric at the medial seam 16. It will further be seen that the folded side portions 12a of cotton tape 12 extend under the folded over side portions 11a of the nylon tricot tape and project between such side portions 11a and the folded-under longitudinal edge portions 11c. Preferably, as shown, the folded-under longitudinal edge portions 11c are of substantially smaller width than the folded over side portions 11a of tape 11 so that the opposite side portions of web 13 are interposed between central portion 12b of cotton tape 12 and the folded side portions 12a of such tape at the regions thereof which are located laterally outward with respect to the folded-under longitudinal edge portions 11c of tape 11.
After tapes 11 and 12 have been folded about thermoplastic web 13 in a manner described above, the folded assembly is suitably heated so as to render molten or at least plastic the thermoplastic material of web 13, whereupon the strap material may be passed between pressure rollers which compress together the several fabric layers so as to cause impregnation of the hot melt or thermoplastic material into the fibers of cotton tape 12 and also into the folded-under longitudinal edge portions 11c of nylon tricot tape 11. Thereafter, the strap material 10 is suitably cooled so as to set the hot melt or thermoplastic material employed for bonding together of tapes 11 and 12.
It is an important feature of this invention that, in the completed strap material 10, the hot melt or thermoplastic material of web 13 does not come in contact with, and therefore does not impregnate either the central portion 11b or the folded side portions 11a of the nylon tricot tape 11 which form the outer shell of the strap material, so that the feel or hand of the nylon tricot shell is not affected by the hot melt or thermoplastic material. Nevertheless, by reason of the bonding of the folded-under longitudinal edge portions 11c of tape 11 to the central portion 12b of cotton tape 12 and the fact that the folded side portions 12a and the central portion 12b of cotton tape 12 underlie and are coextensive with the folded side portions 11a and the central portion 11b of the nylon tricot tape 11 constituting the outer shell of the strap material, the cotton tape ensures that the completed strap material will have the necessary resistance to longitudinal stretching and further will resist lateral narrowing or bunching. When cotton tape 12 has a flannel or brushed finish on at least one of its surfaces, as is preferred, the completed strap material 10 will have a plump or cushioned feel and appearance.
In the above description of the strap material 10 according to this invention, the hot melt or thermoplastic material for bonding the tapes 11 and 12 has been furnished in the form of a web composed of the thermoplastic material in the solid state, and which is heated to the molten condition following the folding of tapes 11 and 12. However, if desired, the hot melt or thermoplastic material may be applied, in molten condition, to the central portion of tape 12 prior to the folding operations.
Referring now to FIG. 4, it will be seen that a preferred apparatus 100 for producing the shoulder strap material 10 described above with reference to FIGS. 2 and 3 comprises suitable supported supply rolls 111, 112 and 113 from which tapes 11 and 12 and web 13, respectively, are simultaneously drawn. Web 13 is superposed centrally on tape 12 which is, in turn, superposed centrally on tape 11, as shown on FIG. 1. The assembled tapes 11 and 12 and web 13 are passed under a guide roller 114 and then through a conventional folding device 115 which continuously operates to fold the longitudinal edge portions 11c of tape 11 onto the adjacent edge portions of tape 12. From folding device 115, tapes 11 and 12 and web 13 pass through a further conventional folding device 116 which continuously operates to fold side portions 11a and 12a of tapes 11 and 12 upwardly and inwardly over web 13, that is, to complete the necessary folding operations. Of course, the folding devices 115 and 116 which are shown separate from each other may be combined in a single conventional folding unit.
After tapes 11 and 12 have been folded around web 13, the resulting assembly passes continuously through a suitable heating unit 117 which, as shown, includes confronting upper and lower conductive blocks 118 and 119 defining a shallow, longitudinally extending groove (not shown) between their confronting surfaces and through which the folded assembly of tapes 11 and 12 and thermoplastic web 13 is guided during the heating thereof. The conductive or metal blocks 118 and 119 contain conventional electric heating elements 120 and 121 supplied with electric current through suitable thermostatically regulated circuits (not shown). Preferably, such circuits are controlled so that the upper heating elements 120 will heat the upper surface of the folded assembly to a temperature that is slightly higher than that to which the lower surface of the folded assembly is heated by the lower heating elements 121. For example, when using the specific material identified above for the thermoplastic web 13, it is desirable to control the heating elements 120 and 121 so that the top surface of the folded assembly will be heated to no more than 320° F., while the lower surface of the folded assembly is heated to no more than 300° F.
After web 13 has been rendered molten or at least plastic by the heating thereof in unit 117, the strap material is passed through the nip 122 between pressure rollers 123 which are suitably driven, as by a motor 124. It will be apparent that the driven rollers 123 constitute at least part of the drive by which tapes 11 and 12 and web 13 are withdrawn from the respective drive rolls, and then passed through folding devices 115 and 116 and heating unit 117. The inherent drag or resistance to movement of the tapes 11 and 12 and web 13, particularly through folding devices 115 and 116, gives rise to a substantial tension which, in the case of the nylon tricot tape 11, tends to longitudinally extend the tape and thereby laterally narrow the tape. Such lateral narrowing of nylon tricot tape 11 after passage through folding device 116 tends to open or create a gap at seam 16, and this tendency has constituted a major obstacle to the production of a satisfactory laminated nylon tricot strap material. However, in accordance with the present invention, the apparatus 100 further comprises a device 125 located between heating unit 117 and pressure rollers 123, and preferably relatively close to the latter, which device 125 acts on the folded-over side portions 11a of tape 11 to urge such portions 11a laterally toward each other in response to the movement of the strap material by rollers 123, whereby to ensure that seam 16 is tightly closed upon passage through the nip 122 between rollers 123.
Referring now to FIGS. 5 and 6, it will be seen that the device 125 comprises a horizontal base plate 126 mounted, as by a bracket 127 (FIG. 4) on the frame 128 supporting pressure rollers 123. Base plate 126 is formed, in its upper surface, with a longitudinal, upwardly opening groove or channel 129 which is laterally dimensioned to guide the folded strap material and which has its bottom surface at the level of nip 122. A pressing member 130 is urged downwardly in channel 129 to bear upon the folded overside portions 11a of tape 11 and has a V-shaped notch 131 in its end portion which is first encountered by the strap material during its movement through channel 129 in the direction of arrow 132 on FIG. 5. The notch 131 opens at least at the bottom surface 133 (FIG. 7) of member 130 and may extend through the entire thickness thereof, as shown. The sides 134 of notch 131 converge in the direction of travel 132 of the strap material and enclose an angle a (FIG. 5) that is no greater than 60°. Preferably, such angle a is substantially smaller than 60°. Further, the apex of notch 131 in bottom surface 133 is preferably rounded and tapered into surface 133, as at 135 on FIGS. 6 and 7.
In order to retain member 130 in channel 129, the top surface 136 of member 130 projects upwardly from channel 129 and has a step 137 (FIG. 6) facing in the direction of movement 132 of the strap material. A loading member 138 extends across channel 129 and rests on top surface 136 so as to be engaged by step 137. The opposite end portions of member 138 have holes (not shown) which loosely receive bolts 139 screwed into tapped holes provided in base plate 126, and compression springs 140 are provided on bolts 139 between the heads of the latter and member 138 to urge the latter downwardly. Obviously, the forces exerted by springs 140 can be readily varied by adjustment of bolts 139.
With the device 125 as described, movement of the strap material through channel 129 in response to the rotation of pressure rollers 123 draws folded side portions 11a of tape 11 under pressure member 130 while the latter is urged downwardly by springs 140. Due to the notch 131, the lower surface 133 of member 130 exerts an inwardly directed force on each folded side portion 11a to tightly close the seam 16. The rounded and tapered apex 135 of notch 131 ensures that the fabric of tape 11 will not pucker as it is drawn under pressing member 130.
With its seam 16 thus tightly and uniformly closed, the strap material passes through pressure rollers 123 by which the fabric layers are compressed together and the molten or at least plastic material of web 13 is made to impregnate the confronting fabric layers. After passage between rollers 123, the strap material may be guided by a roller 141 and by other similar rollers (not shown) to follow a sinuous path along which the strap material is suitably cooled.
Although particular embodiments of strap material according to this invention and of an apparatus for producing the same have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of this invention.