Load bearing fabric assembly and method of making a load bearing fabric assembly
A load bearing fabric assembly having a frame, a carrier and a load bearing fabric. The load bearing fabric is attached directly to the carrier. The frame defines view ports to enable visual inspection of the junction between the carrier and the load bearing fabric after the carrier and fabric have been mounted to the frame. A method of manufacturing the carrier for such a load bearing fabric assembly includes the steps of: (a) placing the fabric inside a mold with at least a portion of the fabric directly engaging the surface of the mold; (b) injecting a molten thermoplastic elastomer into the mold to form the carrier, the molten thermoplastic elastomer having a melt point greater than that of the fabric; and (c) permitting the molten thermoplastic elastomer to cure to form a carrier directly on the fabric. In one embodiment, the fabric is positioned so that the entry of molten thermoplastic elastomer urges the fabric against a surface of the mold cavity.
The present invention relates to load bearing fabric assemblies and methods for securing a load bearing fabric to a support structure. “Load bearing fabrics” are high strength, highly durable textiles typically woven from TPE (thermoplastic elastomer) monofilaments and conventional yarns. Load bearing fabrics can have greater strength and durability characteristics than spring steel and other conventional load bearing materials. In addition to enhanced strength and durability, load bearing fabrics are lightweight and typically relatively elastic. Load bearing fabrics are visually appealing and therefore are often exposed during use.
Load bearing fabrics must be properly attached to a support structure to provide the desired strength and durability. One known method for attaching a load bearing fabric to a support structure is to use a pair of interfitting attachment components, generally referred to as a “carrier” and a “frame.” In this method, the carrier is attached to the fabric and the frame is attached to the support structure. The combined carrier and fabric are intersecured with the frame. In many conventional applications, the carrier is installed within the frame so that the fabric is held in a stretched condition. In some applications, the action of installing the carrier within the frame causes the stretching in the fabric to occur. In other applications, the fabric is stretched before installation of the carrier within the frame. In any event, the stretch applied to the fabric stresses the fabric and the attachment of the load bearing fabric to the carrier. If improperly attached, the fabric may separate from the carrier. For example, the bond itself may fail or the fabric may unravel or separate along the periphery of the fabric.
One widely used method for intersecuring the carrier and the fabric is to mold the carrier directly onto the fabric. With this method, the fabric is typically placed within a mold and the carrier is molded with TPE around the fabric. The fabric is thus encapsulated within the carrier. Conventional knowledge indicates that the melt temperature of the TPE used to make the carrier must be about the same as or lower than that of the TPE monofilaments in the fabric. Otherwise, the heat of the molten material may cause the fabric to deteriorate or decay. This requirement restricts the type of TPE used for the carrier to those having a particular melt temperature. Since the stiffness of TPE typically increases as the melt temperature of the TPE decreases, the stiffness of the carrier is thereby limited by the TPE used within the load bearing fabric.
In some applications, it would be advantageous to be able to vary the stiffness of a carrier while using the same fabric. Thus, an improved method for binding the fabric to the carrier is highly desirable.
After the fabric is bonded to the carrier, visual inspection of the bond between the carrier and the fabric may display certain defects. For example, a visual inspection may be able to detect if the fabric was not properly encapsulated by the carrier. However, in some circumstances, the fabric may appear to be properly bonded to the carrier but in fact is not. In these situations, after the carrier is installed within the frame and the fabric has been further stressed, the fabric may pull out of the carrier. A means for detecting insufficient encapsulation of the fabric, unraveling of the fabric or other attachment defects after the carrier is installed in the frame is thus also highly desirable.
SUMMARY OF THE INVENTIONThe aforementioned problems are overcome by the present invention wherein a load bearing fabric assembly having a carrier and a frame is provided with multiple view ports so that the junction of the load bearing fabric and the carrier can be easily inspected when the carrier is installed within the frame.
In one embodiment, the view ports are located generally on the same plane and are spaced equally about the interior of the frame when they are hidden from view during normal use. In another embodiment, the view ports are not equidistant from each other and may be arranged about the exterior of the frame. Additionally, the view ports may be on multiple planes, thereby allowing the inspection of the junction between the load bearing fabric and the carrier at different positions depending upon the location of the junction.
Formation of the carrier is accomplished by injecting molten TPE into a chamber within a mold. The mold is provided with coolant tubes to assist in solidifying the molten TPE. Prior to injection of the molten TPE into the chamber, the load bearing fabric is placed within the chamber. The terminus of the fabric and at least a portion of the fabric are placed against a wall of the chamber. The load bearing fabric is positioned so that the molten TPE when injected into the chamber urges the fabric against the wall of the chamber. Because the load bearing fabric is positioned against the wall, and the wall is at a temperature less than that of the molten TPE, the temperature of the load bearing fabric against the wall will also be less than that of the molten TPE.
The temperature differential between the molten TPE and the load bearing fabric allows the TPE to have a higher melt point than that of the load bearing fabric. The carrier can thus be made of more rigid TPE, allowing the carrier assembly to be used in a variety of applications.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
A load bearing fabric assembly intended for use as a chair seat is shown in
As noted above, the load bearing fabric assembly 10 generally includes a frame 12, a carrier 16 and a load bearing fabric 14. The carrier 16 and load bearing fabric 14 are interconnected to form a carrier assembly 15.
In this embodiment, the frame 12 is a substantially rigid peripheral frame adapted to be mounted to an underlying support structure (not shown). The frame 12 may be secured to the underlying support structure (not shown) in essentially any conventional manner. As shown, the frame 12 of this embodiment defines a continuous channel 50 into which the carrier 16 is installed. Although continuous in this embodiment, the frame 12 and channel 50 may alternatively be discontinuous, for example, having separate spaced-apart left and right segments. In the described embodiment, the frame 12 is injection molded from a polymer having sufficient rigidity to retain the fabric 14 in the stretch condition. The frame 12 may, however, be manufactured from essentially any material having sufficient strength and durability characteristics. The frame 12 defines a plurality of view ports 18 that penetrate the frame 12 to the channel 50. The view ports 18 permit viewing of a portion of the carrier assembly 15 to assess the connection between the fabric 14 and the carrier 16, as described in more detail below.
Carrier 16 of this embodiment is a continuous peripheral component adapted to be fitted within channel 50. In the illustrated embodiment, the load bearing fabric 14 is attached to carrier 16 by molding the carrier 16 directly onto the peripheral edge of the fabric 14. The carrier 16 may alternatively be attached to the fabric 14 using other methods. For example, the carrier may include two halves that are closed about the fabric and interconnected by adhesives, fasteners or other conventional mechanisms. Although the carrier 16 is continuous in the illustrated embodiment, it may alternatively be discontinuous, for example, including discrete segments that may mount to the frame 12. The term “fabric encapsulation line” is used herein to refer to the junction between the fabric 14 and the carrier 16. In direct molding applications, the fabric encapsulation line is that line along which the fabric merges or joins with the carrier. In other applications, the fabric encapsulation line is that line along which the fabric passes into or otherwise forms a junction with the carrier. Accordingly, the term should not be interpreted to be limited to applications in which the fabric is encapsulated within the fabric through a molding process.
The fabric may be essentially any load bearing fabric and may, for example, include a weave of thermoplastic monofilaments and multifilament yarns. If desired, the strands of the fabric may be welded to one another to enhance the overall strength of the fabric. Welded fabrics are not, however, necessary for use of the present invention. For purposes of disclosure, the figures include only a representation of the fabric and are not intended to provide an accurate illustration of the physical structure of the fabric. In many applications, the fabric will include a significantly tighter weave than shown in the drawings. Further, in many applications, the strands of the fabric will run in different directions than shown in the drawings.
As noted above, carrier assembly 15 is installed within frame 12 in channel 50.
Referring again to
Although the view ports 18 are shown as generally oval and spaced roughly an equal distance part around the frame, the view ports could be of different shapes and sizes and at different locations. For example, the view ports could be in different vertical positions around the frame where the encapsulation line is at different vertical positions around the frame. This permits the bond to be inspected at various locations around the carrier assembly 15. Further, the view ports may be vertically extended to permit viewing of a larger vertical area, and thereby facilitating inspection in applications where the encapsulation line may vary in the vertical direction. Alternatively, the view ports could be at different angles with respect to the fabric in order to facilitate viewing areas of the fabric-carrier attachment. Further, the view ports are shown as being defined on the inside of the frame 12 where they are largely hidden from view during use. The view ports may alternatively be disposed on the outside of the frame or in other locations, as desired.
The carrier assembly 15 may be manufactured in accordance with a method that permits the carrier 16 to be manufactured from a TPE having a higher melt point than that of the TPE portions of the fabric 14. This manufacturing process and the associated molding apparatus are described in connection with
As noted above, fabric 14 is placed within the mold 30 so that its peripheral marginal portion is located in the mold cavity defined by the upper portion 32 and lower portion 34. More specifically, the fabric 14 is arranged in the mold 30 so that the terminus of fabric 14 and a portion of fabric 14 are draped against lower wall 38 of chamber 36. Fabric 14 is positioned so as not to cover inlet 40 of sprue 42. As molten TPE enters chamber 36, a skin forms over the exterior front surface of the molten TPE. This skin assists in urging fabric 14 against the exterior wall of chamber 36. After fabric 14 is fully engaged with the exterior wall of chamber 36, the TPE begins to cure and bonds with fabric 14. The TPE eventually fills the entire chamber. The coolant tubes 44 circulate coolant that lowers the temperature of lower portion 34. Thus, as fabric 14 is maintained in juxtaposition with lower wall 38, the fabric 14 will be maintained at a temperature below that of the molten TPE. Generally, the linear distance where fabric 14 is in contact with the mold surface should be about 0.20 inch or greater. This distance may, however, vary from application to application depending primarily on the characteristics of the fabric and the carrier and the load requirements for the assembly. For example, lesser distances may be necessary when the fabric includes welded strands and greater distances may be necessary when larger loads are to be supported. As a result of the cooling provided by the mold 30, the TPE monofilaments of fabric 14 do not fully melt upon contact with the molten TPE. Rather, the TPE monofilaments maintain their structure and the fabric 14 becomes integral with carrier 16. As can be seen, because the fabric 14 is maintained at a temperature below that of the melt temperature of the TPE used in carrier 16, the melt temperature of the TPE used in carrier 16 can be higher than that of the TPE monofilaments within carrier 16. By using TPE with a higher melt point, the carrier 16 can be made of more rigid TPE, and thus improve the overall strength and durability of the assembly 10.
As noted above, the cooling effect of the mold surface helps to prevent damage to the fabric 14 during the carrier 16 molding process. To help ensure engagement of the fabric against the mold surface, it has been found that the best location of fabric 14 with respect to carrier 16 is in configuration such that the molten TPE when it flows into chamber 36 forces fabric 14 against lower wall 38. For example, if it is desirable to have the fabric 14 follow against the lower mold surface, the sprue 42 is positioned in the mold so that molten material will be introduced into the mold cavity above the fabric 14. The molten material will then flow against and push the fabric 14 down into contact with the mold surface. Alternatively, lifters or slides could be provided within mold 30 to maintain fabric 14 against lower wall 38. Lifters or slides could also be desirable in portions of mold 30 where the fabric 14 tends to fold or otherwise lift away from lower wall 38. For example, it might be preferred to use lifters or slides at the corners of carrier 16 or where there are cuts in fabric 14 to insure contact between fabric 14 and lower wall 38.
The above description is that of a preferred embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.
Claims
1. A load bearing fabric assembly comprising:
- a carrier;
- a load bearing fabric attached to said carrier; and
- a component receiving said carrier and said fabric, said component defining a first view port for viewing a junction between said carrier and said fabric.
2. The load bearing fabric assembly of claim 1 wherein said component defines a second view port for viewing said junction.
3. The load bearing fabric assembly of claim 2 wherein said first view port and said second view port are defined in said component in different planes.
4. The load bearing fabric assembly of claim 3 wherein said component is further defined as a frame, and said first view port and said second view port being defined as apertures in said frame.
5. The load bearing fabric assembly of claim 4 where said frame has an interior and said first view port is located on said interior.
6. A load bearing fabric assembly comprising:
- a frame;
- a carrier, said carrier intersecured with said frame;
- a load bearing fabric attached to said carrier along a line; and
- wherein said frame defines a plurality of view ports for viewing at least portions of said line.
7. The load bearing fabric assembly of claim 6 where said plurality of view ports are aligned with said line.
8. The load bearing fabric assembly of claim 7 where said plurality of view ports are contained within more than one plane.
9. The load bearing fabric assembly of claim 8 where said plurality of view ports are spaced equidistant about said frame.
10. The load bearing fabric assembly of claim 8 where said frame defines a channel, said carrier being fitted within said channel, said view ports extending through said frame to said channel to permit viewing of said line.
11. A method of manufacturing a carrier assembly comprising:
- supplying a load bearing fabric having a melt temperature, the load bearing fabric having a terminus;
- placing the terminus into a mold cavity, the cavity being defined by at least one mold surface;
- insuring that a portion of the fabric within the mold cavity is against the mold surface;
- supplying molten thermoplastic elastomer to the cavity, the molten thermoplastic elastomer having a substantially higher melt temperature than the load bearing fabric; and
- cooling the molten thermoplastic elastomer.
12. The method of claim 11 further comprising the step of holding at least a portion of the load bearing fabric against the mold surface.
13. The method of claim 12 wherein the thermoplastic elastomer has a thermoplastic elastomer melt point and the load bearing fabric has elastomeric elements with a load bearing fabric melt point, and the thermoplastic elastomer melt point is greater than the load bearing fabric melt point.
14. The method of claim 13 where the step of placing the terminus into the chamber further comprises positioning the load bearing fabric such that the molten thermoplastic elastomer moved into the chamber urges at least a portion of the load bearing fabric against the desired mold surface.
15. A method of manufacturing a carrier assembly, the carrier assembly having a carrier, comprising the steps of:
- providing a first thermoplastic elastomer material having a first melt point;
- providing a load bearing fabric having a thermoplastic elastomer material with a second melt point, the first melt point being higher than the second melt point;
- forming a carrier from the first thermoplastic elastomer material in a mold while the first thermoplastic material is above the first melt point; and
- attaching the load bearing fabric to the first thermoplastic elastomer material while the first thermoplastic elastomer material is above first melt point, at least a portion of the load bearing fabric engaging a surface of the mold, whereby the mold cools at least a portion of the load bearing fabric during said forming step.
16. The method of claim 15 further comprising the step of:
- maintaining the temperature of at least a portion of the load bearing fabric in contact with the thermoplastic elastomer material below the second melt point while the thermoplastic elastomer material is at a temperature above the first melt point.
17. The method of claim 16 further comprising the step of:
- cooling the thermoplastic elastomer material.
18. A load bearing fabric assembly comprising:
- a frame;
- a carrier assembly secured to said frame, said carrier assembly including a load bearing fabric intersecured with a carrier, said carrier assembly manufactured by the steps of (a) placing a portion of said load bearing fabric in a mold with at least a portion of said load bearing fabric directly engaging a surface of said mold, (b) introducing a molten material into said mold in direct contact with said load bearing fabric, said molten material having a melt point greater than a melt point of the load bearing fabric and (c) permitting said molten material to cure in said mold in direct contact with said load bearing fabric.
19. The assembly of claim 18 wherein at least a portion of said load bearing fabric is fused with said carrier.
20. The assembly of claim 19 wherein said fabric includes a peripheral marginal portion, said carrier extending along at least a portion of said peripheral marginal portion.
21. The assembly of claim 20 wherein said carrier includes an outer surface, said fabric being integrally molded to at least a portion of said carrier along at least a portion of said outer surface.
22. The assembly of claim 19 wherein said fabric joins said carrier along a line of encapsulation, said fabric remaining along said outer surface of said carrier for a distance from said line of encapsulation.
23. The assembly of claim 22 wherein said distance is at least 0.20 inches.
24. The assembly of claim 23 wherein said distance is at least 0.25 inches.
25. A load bearing fabric assembly comprising:
- a carrier manufactured from a first thermoplastic elastomer, said first thermoplastic elastomer having a first melt temperature, said carrier having an outer surface; and
- a load bearing fabric attached to said carrier, said load bearing fabric manufactured at least in part from a second thermoplastic elastomer, the second thermoplastic elastomer having a second melt temperature, wherein the first melt temperature is higher than the second temperature, said load bearing fabric being encapsulated along said outer surface of said carrier.
26. The load bearing fabric assembly of claim 25 further including a frame, said carrier being interfitted with said frame.
27. The load bearing fabric assembly of claim 26 wherein said load bearing fabric and said carrier are attached at a junction, and said carrier has a first view port for viewing said junction at a first location to permit visual inspection of the said junction.
28. The load bearing fabric assembly of claim 27 wherein said carrier has a second view port for viewing said junction at a second location different from said first location.
29. The load bearing fabric assembly of claim 28 wherein said first view port and said second view port are generally on a common plane.
30. The load bearing fabric assembly of claim 28 wherein said first view port and said second view port are in different planes.
31. The load bearing fabric assembly of claim 28 wherein said frame defines a channel, said carrier being fitted within said channel.
32. The load bearing fabric assembly of claim 21 wherein said first view port and said second view port extend through said frame to said channel.
33. The load bearing fabric assembly of claim 32 wherein said frame includes an interior surface, said first view port and said second view port being located along said interior surface.
Type: Application
Filed: Jul 30, 2004
Publication Date: Feb 2, 2006
Inventor: Timothy Coffield (Grand Rapids, MI)
Application Number: 10/903,947
International Classification: B32B 3/10 (20060101);