Sewing as a method for joint reinforcement between plastics and other materials

A method for reinforcing joints between one or more components is presented. Adhesive is applied to joint areas of contact between the components and the components are stitched together at the joint areas to ensure that the joints are mechanically stable enough to withstand stresses such as pressurization and external manipulation.

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INCORPORATION-BY-REFERENCE OF COMPUTER PROGRAM APPENDIX

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NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

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BACKGROUND

1. Technical Field

The technology of this disclosure pertains generally to mechanically integrating plastic components with other components, and more particularly to reinforcing adhered joints between plastic components and other components.

2. Background Discussion

The use of rubber, silicone, and other plastic compounds to make molds for various engineering applications is a rapidly growing industry. The flexibility and tensile strength of silicone and rubber compounds are desired qualities for many applications, including designing and building three-dimensional (3D) molds with precise structural features. However, a common occurrence is that silicone molded units must be combined either with other silicone or plastic molded products or with structural components made of metals or other materials. In these cases, it is necessary to mechanically integrate various components using adhesive compounds. The use of adhesives to join two pieces of plastic material or a plastic and a non-plastic component may be sufficient for many practical applications. However, in several circumstances, the mechanical strength of the adhesive per unit of joint area is insufficient and often the contact area is subject to deterioration from external manipulation.

The standard method to ensure gas or liquid tightness in plastic molds with circulating fluids is to manufacture them as a single piece using standard molding procedures. However, due to the complexity of some integrated designs or the need to use different types of materials, it becomes necessary to use adhesives to join various parts. How to ensure mechanically stable joints that are subject to either stresses inherent to their function (e.g. pressurized joints) or to external manipulation, is an outstanding and unresolved issue in the industry. Though the adhesive industry has made great progress in offering a wide range of compounds with excellent properties to adhere joints that are gas or liquid tight, a serious problem is that the resistance to pressurization is often quite limited.

BRIEF SUMMARY

Embodiments of the present disclosure can avoid the shortcomings of the standard methods for ensuring joints are mechanically stable enough to endure stresses such as pressurization by using stitches (made with threads of nylon or other materials) as reinforcements in either homologous joints (same compound) or heterologous joints (e.g. metal/silicone, rubber/silicone, any plastic/rubber, etc.).

In one embodiment of the present disclosure, an adhesive material can be applied to the area where a joint will be formed by integrated components. The adhesive can be placed on either of the component pieces. After the adhesive is applied, the pieces can be pushed together to join and seal the opposing surfaces at the joint areas. Using a stitching material, the component pieces may then be stitched together at the joint areas to reinforce the joint areas of contact.

In another embodiment of the present disclosure, a molded component made from a synthetic material such as plastic, silicone, rubber, etc. is joined to a metal plate. A sewing guide pattern is created on the metal plate by drilling holes in the plate along the sections that will form the joint areas. Holes may or may not be drilled in the mold component, depending on whether or not the mold component material can be pierced by the sewing tool. Adhesive is applied to one or both of the components on the portions that will form the joint areas. The metal plate and mold components are pushed together to form the adhered joint areas of contact. Using a stitching material, the metal plate and mold component are then stitched together at the joint areas using the pattern of holes that were drilled into the metal plate as a guide.

DETAILED DESCRIPTION

Described herein are methods for reinforcing the mechanical stability of joints formed when two or more components are joined together using sewing material to sew along the joint areas, thereby attaining superior resistance to pressure and external handling. The joints may be made gas or liquid tight by adjusting the tightness of the stitches during the sewing process and by using adhesives to prevent gas or liquid leaking through the stitches. The stitches maintain the flexibility of the adjoining materials and provide superior performance with respect to alternative reinforcement approaches such as the use of bolts, nails, or staples, which by necessity are made of rigid materials.

Referring more specifically to the drawings, for illustrative purposes, embodiments of the methods for reinforcing joints formed by integrating two or more components, one of which can be made of a plastic material are described herein and depicted generally inFIG. 1throughFIG. 4B. It will be appreciated that the methods may vary as to the specific steps and sequence without departing from the basic concepts as disclosed herein. The method steps are merely exemplary of the order that these steps may occur. The steps may occur in any order that is desired, such that it still performs the goals of the claimed technology.

Referring toFIG. 1A, a schematic diagram of the process100of forming fluid tight joints with a first plastic component102that will be joined to a second plastic component104is shown. In this example, the second plastic component104is shown as a mold that could have been produced using a three dimensional (3D) printer, for example. However, it will be appreciated that the components to be joined can be of any shape or size without departing from the teachings of the present description.

Referring toFIG. 1B, adhesive106is applied to the second plastic component104. The adhesive106can be applied to any of the components to be joined as long as it is applied to the joint areas108. The adhesive106can be RTV silicone, epoxy cement, or any other adhesive recommended for the materials to be joined. After the adhesive106is applied, the two component surfaces are put in contact with each other by applying external pressure to assure the components are glued together with the adhesive, as shown inFIG. 1C.

Once an adhesive seal is attained, and preferably before the adhesive is fully cured, the components can be sewn together at the joint areas of contact108using a standard awl110with a threaded needle112, as shown inFIG. 1D. One of ordinary skill in the art will appreciate that any other tool appropriate for the component materials and application may be used. As an alternative to using a manual awl110, a sewing machine (not shown) could also be used to sew stitches for adequate reinforcement of joints. The sewing process is similar to sewing together two pieces of leather or denim. Thread114, including nylon monofilaments, silk, or cotton of various diameters and strengths, can be used for stitching, depending on the application. Care should be taken to tighten each stitch.

FIG. 2AandFIG. 2Bare schematic diagrams showing close up views200of the stitching through the two components102,104that have been joined together by adhesive108.FIG. 2Ashows the upper stitches202with knots204that can be used to secure the stitching. InFIG. 2B, the lower stitches206are shown with knots204that can be used to secure and tighten the stitching.

EXAMPLE

While the use of adhesives alone to join two pieces of plastic materials may be sufficient for many practical applications, in several circumstances, the mechanical strength of the adhesives per unit of joint area is insufficient and often subject to deterioration at the contact area by external manipulation. Though these are general issues, they are a common problem whenever metal or rigid plastic plates must be used to seal cavities in which the joint surface area is relatively small with respect to the overall dimensions of the object.

FIG. 3AthroughFIG. 3Eshow an example embodiment of the method300, in which a 0.006 inch copper sheet302was joined to a three-dimensional (3D) silicone mold304with an internal cavity, as shown inFIG. 3A.

In this example, small holes306were drilled into the copper sheet302forming a pattern to pre-match the joint areas of contact308, as shown inFIG. 3B. The size of these holes depends on the type of needles and threads to be used. In this example, a #57 drill bit was used for a regular point titanium commercial (100/16) sewing machine needle. However, the aspects of the approach do not depend on the particular choice of needle or hole size.

Referring toFIG. 3C, an adhesive310(RTV silicone, epoxy cement, or any other adhesive recommended for the materials to be joined) is then applied to the joint areas of contact308of the plastic (silicone) mold304. Although not shown, the adhesive may also be applied to the copper (metal) plate302. Subsequently, the copper plate302and the plastic mold304were put in contact with each other by applying external pressure to assure the components were glued together with the adhesive310, as shown inFIG. 3D.

Referring toFIG. 3E, once the adhesive seal was attained, the mold304and plate302were sewn together using a standard awl312with a threaded needle314or any other tool appropriate for the component materials and application, following the predetermined pattern of holes. The sewing process is similar to sewing together two pieces of leather or denim. In this specific example, microfilament braided fishing line (65 lb. test; 0.41 mm in diameter) was used as the thread316. Other threads, including nylon monofilaments, silk, or cotton of various diameters and strengths, can be chosen depending on the application. Care was taken to tighten each stitch.

FIG. 4AandFIG. 4Bare schematic diagrams400illustrating the features of two finished stitches402,406across the metal plate302and plastic mold304. It should be noted that in this example embodiment, the plastic mold304does not have pre-set holes306because the needle314and thread316can readily penetrate it, creating a tight seal around the thread316. In other applications of the present technology, however, it may be necessary to drill pre-set holes306matching those in the metal plate302.FIG. 4Ais a top perspective detail view that shows the upper stitches402with knots404that can be used to secure the stitching. InFIG. 2B, the lower stitches406are shown with knots404that can be used to secure the stitching402,406.

As an alternative to using a manual awl312, a sewing machine (not shown) could be used to sew stitches for adequate reinforcement of joints areas of contact308. When using a sewing machine to sew a metal plate (or foil) to a plastic structure, the pre-drilled holes in the metal plate should be carefully distanced apart along a straight line in order to match the pitch of the machine. If this precaution is taken, once the holes are made in the metal plate, it will be sufficient to align the first stitch and then automatically proceed over an entire joint.

The technology of this disclosure is particularly well-suited for use when air or water tight joints between components of the same or dissimilar materials are desired. In this case, the use of adhesives alone is usually insufficient for the joints to support pressurization. The advantage of the use of stitching, as described herein, is that the joints are mechanically reinforced while maintaining their overall flexibility, intrinsically provided by the properties of the stitching material.

The technology of this disclosure has been tested and found to provide superior reinforcement of joints between metals and silicone molds. Using a wide variety of commercial RTV adhesives typically recommended for water/air tight seals, stitch reinforcement as described herein creates stable air/water tight joints when tested under pressure. Under identical conditions, unreinforced joints invariably failed, resulting in separation of the joint surfaces and allowing water and/or gas to flow through the joints.

1. A method for joining two components with mechanically stable joints, the method comprising: applying an adhesive between a first component and a second component, wherein the adhesive is applied to an area of contact between the first component and the second component forming one or more joint areas; bringing opposing surfaces of the components into contact; applying compressive pressure to the components to join and seal the opposing surfaces in the one or more joint areas of contact; and using a stitching material, stitching the first component to the second component at the one or more joint areas.

2. The method of any preceding embodiment, wherein the stitching material is a plastic thread or a natural thread material.

3. The method of any preceding embodiment, further comprising: tightening stitches of the stitching material such that a gas and liquid tight seal is formed between the components in the joint areas of contact.

4. The method of any preceding embodiment, wherein stitching the first component to the second component at the one or more joint areas maintains flexibility of the components in the joint areas of contact.

5. The method of any preceding embodiment, further comprising: drilling a pattern of holes in the first component; and stitching the first component to the second component at the one or more joint areas using the pattern of holes in the first component as a guide.

6. The method of any preceding embodiment, further comprising: drilling a pattern of holes in the second component that match the pattern of holes in the first component.

7. The method of any preceding embodiment, wherein stitching the first component to the second component creates a tight seal around the stitching material with adhesive and one or more knots.

8. A method for joining a metal plate and a synthetic mold with mechanically stable joints, the method comprising: drilling a pattern of holes in a metal plate corresponding to desired joint areas of contact between the metal plate and a synthetic mold; applying an adhesive between the metal plate and the mold in one or more joint areas of contact; bringing opposing surfaces of the metal plate and the mold into contact; applying compressive pressure to the plate and the mold to join and seal the opposing surfaces in the one or more joint areas of contact; and using a stitching material, stitching the metal plate to the mold using the pattern of holes in the metal plate as a guide.

9. The method of any preceding embodiment, wherein the stitching material is a plastic thread or a natural thread material.

10. The method of any preceding embodiment, further comprising: tightening stitches of the stitching material such that a gas and liquid tight seal is formed between the components in the joint areas of contact.

11. The method of any preceding embodiment, wherein stitching the metal plate to the mold at the one or more joint areas maintains flexibility of the joint areas of contact.

12. The method of any preceding embodiment, further comprising: drilling a pattern of holes in the mold that match the pattern of holes in the metal plate.

13. The method of any preceding embodiment, wherein stitching the first component to the second component creates a tight seal around the stitching material with adhesive and one or more knots.