US20060150331A1 - Channeled warming blanket - Google Patents

Abstract

A warming blanket incorporating channeled areas for accepting heat and/or sensor wires. The inventive blanket includes multiple layers of knitted, woven or non-woven fabrics that are welded together with ultrasonic seams to define channels through which wires for resistive heating can be placed. This composite may be produced in a continuous process, providing the composite in roll form.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims the benefit of and priority from U.S. Provisional patent application Ser. No. 60/643,354, filed on Jan. 12, 2005 the contents of which are hereby incorporated by reference in their entirety as if fully set forth herein.
TECHNICAL FIELD
• This invention relates generally to warming blankets. More particularly, the invention relates to warming blankets including channeled areas for accepting heat and/or sensor wires. These channeled areas are bounded by welded zones disposed in a pattern across the warming blanket. A method of forming such a warming blanket is also provided.
BACKGROUND
• Warming blankets with channels are well known in the art and are available from a variety of sources. Many of these blankets are formed by weaving two layers of cloth simultaneously, creating a blanket with a pattern of channels for accepting a heat and/or sensor wire. A limitation of the prior process is that interweaving of fabric layers does not allow for the incorporation of additional layers of material such as batting for thermal insulation. Moreover, interweaving of layers to form the channels necessitates the use of woven cloth which limits design options and which may increase cost and weight. Accordingly, the need exists for an improved channeled warming blanket that avoids these limitations.
SUMMARY
• The present invention provides advantages or alternatives over the prior art by providing a warming blanket shell having multiple layers on each side welded together with ultrasonic seams to create channels through which wires for resistive heating can be placed. The wires are arranged between two opposing non-woven layers, thereby creating a low friction, low stretch channel for the wire.
• According to one aspect of the invention a warming blanket shell is provided having two opposing interior layers of non-woven fabric with layers of decorative fabric disposed on each outer surface of these non-woven layers and ultrasonic weld seams joining the non-woven layers together. The ultrasonic weld seams extend in a pattern to define channels to accept heat and/or sensor wires. Optionally, a layer of high loft batting may be disposed between at least one non-woven layer and a decorative fabric outer layer. The warming blanket shell may be produced in roll form for use with automated wiring equipment.
• According to another aspect of the invention a method of producing a composite warming blanket shell is provided. The method utilizes a series of rotating anvils that interact with an array of cooperating ultrasonic horns to create a pattern of ultrasonic seams, thereby forming channels which can accept heat and/or sensor wire.
BRIEF DESCRIPTION OF THE DRAWINGS
• The present invention will now be described by way of example only, with reference to the accompanying drawings which constitute a part of the specification herein and in which:
• FIG. 1 is a cross section of an exemplary warming blanket composite after wiring;
• FIG. 2 is an overhead view of a warming blanket composite showing an exemplary channel pattern;
• FIG. 3 is a schematic view illustrating an exemplary formation line for a multi-layer warming blanket;
• FIG. 4 is a cross machine view taken along line4-4 inFIG. 3.
DETAILED DESCRIPTION
• Exemplary embodiments of the invention will now by described by reference to the drawings wherein like elements are designated by corresponding reference number throughout the various views. InFIG. 1, awarming blanket8 is shown. As illustrated the warming blanket includes a firstinner layer10 and a secondinner layer10′ disposed in opposing relation to one another. Theinner layers10 and10′ are preferably of non-woven fibrous construction and more preferably of spun-bond non-woven fibrous construction. Theinner layers10,10′ may be formed of fibers including polyester, polypropylene, or any other ultrasonically fusible fiber material. Although the weight of the inner layers can vary greatly, the layers should be of sufficient strength to provide a stable channel for wiring without increasing the composite stiffness significantly. Preferably, the mass per unit area of each of theinner layers10,10′ is between about 0.40 oz/yd²and about 1.1 oz/yd². This provides a low stretch, low friction channel through which to insert the wire.
• As shown, the exterior is preferably defined by a first decorativeshell fabric layer14 and a second decorativeshell fabric layer14′. The shell fabric can be a warp knit, circular knit, nap knit micro-denier, woven, non-woven, needle punch construction formed from suitable ultrasonically fusible fibrous materials including polyester, polypropylene or the like. Although the weight can vary over a wide range, the amount of material affects the ultrasonic welding speed and efficiency. The preferable mass per unit area for the decorative shell fabric layer is in the range from about 2.5 oz/yd²to about 6.0 oz/yd².
• According to one contemplated embodiment, alayer12 may also be present between one or both decorativeshell fabric layers14 and14′ and the correspondinginner layers10 and10′. In the illustrated embodiment, the layered composite comprises onelayer12 situated between the inner side of the outershell fabric layer14 and the outer side of the adjacentinner layer10.Layer12 can be a batting layer of relatively high loft material for thermal insulation. In this particular example, the outershell fabric layer14 defines the top of theblanket8 so that the batting traps the heat generated and radiates such heat downwards towards the user. Furthermore, the batting is particularly useful in creating both a three-dimensional structure to the final composite and in masking the tactile perception of the heating wires by the user. The batting is preferably a polyester resin-bond with a loft of between 0.125 inches and 0.50 inches. It should have adequate wash stability, and should not contribute to the overall flammability of the composite.
• As previously indicated and according to a contemplated practice, thewarming blanket8 is further defined by a plurality of ultrasonic seams which create welded areas16 (FIG. 2) where the fabric has been ultrasonically fused and non-weldedareas18 where the fabric has not been ultrasonically fused. Thewelded areas16 define fused seams of pre-determined length and width in which theouter layers14 and14′ as well as theinner layers10 and10′ and theoptional layer12 are linked together. The formation of these seams in which the distances between theouter layers14 and14′ and between theinner layers10 and10′ have been dramatically decreased compared to the corresponding distance in thenon-welded areas18, createschannels20 in the non-welded areas. These channels are situated between theinner layers10 and10′ and extend in patterns parallel to thewelded areas16. As shown inFIG. 1, heat/sensor wire22 can be inserted in thechannels20 between the twoinner layers10 and10′ utilizing automated wiring equipment.
• By way of example only, and not limitationFIG. 2 shows one exemplary pattern of channels defining welded and non-welded areas, formed utilizing the method described herein. As shown, ultrasonic seams defined by the welded areas extend longitudinally along the planar dimension of the warming blanket and define a series of channels that can accept heat and/or sensor wire. The seams are represented by thewelded areas16 which are of a predetermined length and width. The majority of the blanket is non-welded18.
• FIG. 3 provides one non-limiting example of a process for forming the inventive warming blanket composite shell. In the illustrated arrangement, the let-off rolls are arranged such that the two non-wovenlayers10 and10′ are in adjacent opposing relation. Theoptional batting layer12, if present, is on an outer side of one or both of the non-woven layers, and thedecorative shell fabrics14 and14′ are on either side of the entire composite. During processing, the layers proceed through a gap between an array ofultrasonic horns24 and a series of rotatinganvils26. One anvil wheel is provided for each channel boundary and the anvils can be individually actuated in an up and down motion. When an anvil is in the “up” position, the horns direct the relatively high frequency ultrasonic vibration onto the fabric layers held in close proximity by the supporting rotating anvils causing localized frictional heating along a narrow, relatively continuous band and concomitant welding to form a seam. When the anvil is in the “down” position, the fabric layers pass through with no welding occurring.
• The anvils can be computer controlled to create a pre-determined pattern with a repeat length that is programmable into the controller. Thus, conventional warming blanket design which necessitates channel termination prior to reaching the edge of the blanket shell to allow for normal electrical connections is easily achieved. Blankets of any length can be produced, and blankets of different lengths can be produced on the same equipment with only minor changes to the program. In addition, theanvils26 are attached to a frame28 (shown inFIG. 4) and can be positioned across the frame with variable spacing. Thus, the number of channels, the spacing between the channels, and the length of each individual channel can be adjusted without major equipment modifications in a timely and cost effective manner. Furthermore, uniform heating is assured by the uniform disposition of channels and electrical heating wires across the length and width of the blanket. This also avoids contact or close proximity of adjacent wires and concomitant overheating.
• This method of production allows the blanket composite to be manufactured in roll form, thus avoiding the costly and labor intensive cut and sew steps required with the production of individual blankets. Moreover, automated wiring equipment can only be employed if the composite is in roll form.
• As a variation of the described method, it is contemplated that the first and second non-woven layers may be ultrasonically welded to form channels for heat/sensor wires. Subsequently, the first and second outer decorative fabric layers may be attached to the fused non-woven layers by any attachment means available to those in the art including sewn seams, adhesion or the like.
• The inventive concepts may be further understood by reference to the following non-limiting example.
EXAMPLE 1
• A composite is formed with a 4.5 oz/yd²napped circular knit fabric, a layer of 1.75 oz/yd²polyester batting (0.25 inch loft), two layers of 1.1 oz/yd²polyester spun-bond non-woven, and another layer of the 4.5 oz/yd²napped circular knit polyester. The composite is welded together in a pattern such as that displayed inFIG. 2. The composite is then cut into individual blankets and a heater wire is inserted in a serpentine pattern throughout the channels such that the end point is the original starting location.

Claims (23)

1. A warming blanket composite shell comprising:

a first non-woven layer;

a second non-woven layer;

a first decorative fabric layer disposed on an outer surface of said first non-woven layer;

a second decorative fabric layer disposed on an outer surface of said second non-woven layer; and

a plurality of ultrasonic weld seams bonding the non-woven layers and decorative fabric layers together, wherein the ultrasonic weld seams are arranged in a pattern defining boundaries of wire accepting channels.

2. The invention ofclaim 1 wherein said composite shell is in roll form.

3. The invention ofclaim 1 wherein at least a portion of said weld seams are discontinuous along the length of the warming blanket composite shell.

4. The invention ofclaim 1 wherein said first and said second non-woven layers comprise spun-bond non-woven fabrics.

5. The invention ofclaim 1 wherein said first and said second non-woven layers are characterized by a fabric weight about 0.40 oz/yd²to about 1.1 oz/yd².

6. The invention ofclaim 1 wherein an ultrasonically fusible batting layer is disposed between said first non-woven layer and said first decorative fabric layer.

7. The invention ofclaim 6 wherein said batting layer is polyester resin-bond batting.

8. The invention ofclaim 6 wherein said batting layer is characterized by a loft of about 0.125 inches to about 0.50 inches.

9. The invention ofclaim 6 wherein said batting layer is characterized by a mass per unit area of about 1.1 ounces per square yard.

10. The invention ofclaim 1 wherein said first and said second decorative fabric layers are selected from the group consisting of a warp knit, circular knit, nap knit micro-denier, woven, non-woven, and needle punch fabric.

11. The invention ofclaim 10 wherein said first and said second decorative fabric layers are nap knit micro-denier fabric.

12. The invention ofclaim 10 wherein said first and said second decorative fabric layers are characterized by a fabric weight of about 2.5 oz/yd²to about 6.0 oz/yd².

13. The invention ofclaim 1 wherein said weld seams comprise elongate lines of a predetermined length.

14. A method of producing a composite warming blanket shell comprising the steps of;

(a) arranging let-off rolls such that two non-woven layers are adjacent to one another; and

(b) disposing of a first and second decorative fabric layers on the outer surfaces of said non-woven layers; and

(c) applying a plurality of ultrasonic weld seams across the non-woven layers and decorative fabric layers thereby bonding the non-woven layers and decorative fabric layers together such that the ultrasonic weld seams are arranged in a pattern defining boundaries of channels adapted to accept wire elements.

15. The method ofclaim 14 wherein said first and said second non-woven layers comprise spun-bond non-woven fabrics.

16. The method ofclaim 14 wherein said first and said second non-woven layers comprise a fabric characterized by a weight of about 0.40 oz/yd²to about 1.1 oz/yd².

17. The method ofclaim 14 comprising the further step of disposing a batting layer between said first non-woven layer and said first decorative fabric layer.

18. The method ofclaim 17 wherein said batting layer is polyester resin-bond batting.

19. The method ofclaim 17 wherein said batting layer is characterized by a loft of about 0.125 inches to about 0.50 inches.

20. The method ofclaim 17 wherein said batting layer is characterized by a mass per unit area of about 1.1 ounces per square yard.

21. The method ofclaim 14 wherein said first and said second decorative fabric layers are selected from the group consisting of a warp knit, circular knit, nap knit micro-denier, woven, non-woven, and needle punch fabric.

22. The method ofclaim 21 wherein said first and said second decorative fabric layers are nap knit micro-denier fabric.

23. The method ofclaim 21 wherein said first and said second decorative fabric layers are characterized by a fabric weight of about 2.5 oz/yd²to about 6.0 oz/yd².

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