WO2009137906A1

WO2009137906A1 - Assembly system for canvas stretcher frames

Info

Publication number: WO2009137906A1
Application number: PCT/CA2008/000879
Authority: WO
Inventors: Paul Vaz
Original assignee: Artex Picture Frames Ltd.
Priority date: 2008-05-12
Filing date: 2008-05-12
Publication date: 2009-11-19

Abstract

The present invention relates to the stretching of canvas or other flexible materials (such as printed photographs, artwork, illustrations, gallery wrap) on a stretching frame to be displayed without the use of a conventional picture frame. This invention is designed to be sold as a kit which can be assembled by an unskilled end user without the use of stretching pliers and staplers (which require considerable strength and skill). The present invention allows for the tucking of the corner folds of canvas inside the mitered corners for a neater result than then the standard stretching systems available today. The finished product will have no side edge fasteners, unsightly corner folds or wrinkles. Tension is added to the finished product by means of corner tensioners which are snug-fit into corresponding grooves in the stretcher bars.

Description

ASSEMBLY SYSTEM FOR CANVAS STRETCHER FRAMES

FIELD OF INVENTION

This invention concerns stretching frames for use with canvas or other flexible materials such as printed photographs, artwork and illustrations. In particular, this invention relates to a stretching frame having a bracing system to keep the frame square for use by novice framers.

BACKGROUND OF THE INVENTION

Most prior art stretcher bars are manufactured as standard dimension lengths with machined ends. These lengths are assembled into frames with interlocking corners. The canvas or other material is stretched on this frame using stretching pliers and with staples on the side. Wedges can be inserted into the interlocking corners to expand the frame and tension the canvas. This type of product has been around for a long time, however stretchers of this type have a few disadvantages:

• When first assembled the stretcher bars must be squared and aligned by the user or the diagonals will be off making subsequent framing difficult or impossible.

• The stretching of the material on the stretchers requires the use of specific tools like stretching pliers and staple guns both of which are costly and might not be available in the average consumers household.

• The above mentioned stretching system requires a fair amount of skill, strength and practice in order to get good results thus it is intimidating and not user friendly.

• In this type of stretching the staples are normally placed on the side of the stretchers which makes the side edges of the canvas unsightly.

• The corners of the material must be folded and fastened on the sides adding bulk and detracting further from the edge appearance of the finished product.

• The sophisticated nature of the machined ends of the above mentioned stretchers do not allow for resizing and therefore cannot be used if the dimensions of the art work to be stretched does not fall within the standard sizes currently being manufactured.

• Currently available stretchers allow for expansion with the use of wedge inserts into the interlocking corners. These inserts however are often missing from the corners making it impossible to retighten the corners without them.

With the popularity of digital cameras, it has been possible for the ordinary consumer to take and print their own photographs using desktop tools. It is popular to display one's photographs in a variety of ways, and a simple method of displaying these photographs using a stretching frame would be advantaegeous.

SUMMARY OF THE INVENTION

The present invention relates to the stretching of canvas or other flexible materials such as printed photographs, artwork and illustrations on a stretching frame to be displayed without the use of a conventional picture frame. This invention is designed to be sold as a kit which can be assembled by an unskilled end user without the use of stretching pliers and staplers (which require considerable strength and skill). The present invention allows for the tucking of the corner folds of canvas inside the mitered corners for a neater result than then the standard stretching systems available today. The finished product will have no side edge fasteners, unsightly corner folds or wrinkles.

The present invention provides four stretcher bars mitered at both ends which are adhered to a flexible rectangular material to create a stretching form 40. The stretcher bars are fastened to this material in such a manner that when the stretcher bars are rotated axially by 90 degrees the mitered corners meet to form a closed frame.

A unique feature of the present invention is the use of double sided tape to adhere the canvas to the stretching form 40. This is accomplished by allowing the user to adhere the canvas to the stretching form 40 while it is in the initial open position. The canvas is stretched by the rotation of the stretcher bars 90 degrees axially into the final position.

At each mitered corner two grooves are provided which run perpendicular to the length of the bars. A "U" shaped fastener or staple is inserted into these groves to keep the miters from separating.

Each stretcher bar has a centre groove which can be used for hanging the finished product. Each stretcher bar has two additional grooves which are spaced equally apart from the centre groove and cut to receive corner tensioners which act to add tension of the stretching form 40 in its final position.

This invention allows the user to take a canvas and apply it to a stretching frame where the only tool needed is a pair of scissors.

BRIEF DISCRIPTION OF DRAWINGS

Embodiments of the invention will now be described with reference to the following drawings in which:

FIG. Ia is a top of a stretcher bar.

FIG. Ib is front view of the stretcher bar of FIG. Ia.

FIG. Ic is a bottom view of the stretcher bar of FIG. Ia.

FIG. 2a is a front view of a U shaped fastener.

FIG. 2b is a side view of the U shaped fastener of FIG. 2a

FIG. 2c is a bottom view of the U shaped fastener of FIG. 2c.

FIG. 3a is a top view of a corner tensioner. FIG. 3b is a front view of the corner tensioner of FIG. 3a.

FIG. 3c is an end view of the corner tensioner of FIG. 3a.

FIG. 4a. is a top view of the double sided adhesive tape.

FIG. 4b is an end view of the double sided adhesive tape.

FIG. 5 is a top view of the flexible rectangular material to which the stretcher bars and the double sided adhesive tape is affixed to form the stretching form 40.

FIG. 6 is an exploded perspective view showing all elements of the stretching form 40.

FIG. 7a is a top view of the stretcher form of FIG. 1 before being positioned on the canvas.

FIG. 7b is right side view of the stretcher form of FIG. 7.

FIG. 7c is a bottom view of the stretcher form of FIG. 7.

FIG. 8 is a perspective view of the stretcher form after being positioned on the canvas, showing the cutting of the corners of the canvas and the adhering of the corners to the miters of the stretcher bars.

FIG. 9 is a perspective view showing the folding of the stretcher from into its final position, and the subsequent insertion of the U shaped fasteners or staples.

FIG 10a. is a bottom view (being the display side) of the finished product.

FIG. 10b is a side view of the finished product.

FIG. 1 Oc is a top view of the finished product showing the corner tensioners inserted into the corresponding grooves of the stetcher bars. DESCRIPTION OF PREFERED EMBODIMENTS

FIG, Ia, Ib, Ic and Id shows the features of each of four stretcher bars 1. Each stretcher bar 1 has a miter 2 at each end. On the top of each stretcher bar 1 there is a centre groove 4 and two grooves 13 which are equally spaced on either side of the centre groove 4. On the bottom of the stretcher bar 1 , a groove 3 runs parallel to each miter 2

FIGS. 2a, 2b, and 2c shows the U shaped fastener or staple 5 which is inserted by hand into groove 3 to keep the stretching form 40 closed once it has been positioned and adhered to the canvas 30.

FIG. 3a, 3b and 3c shows one of the four corner tensioners 12 which are placed diagonally in a snug fit in the grooves 13 of the stretcher bars 1 to increase tension of the canvas 30.

FIG. 4 shows the double sided adhesive tape 20. This tape is formulated to adhere to wood as well as to canvas and other material (such as plastic, metal and so forth). The tape 20 has an adhesive substrate covered by strips of release paper to be removed only when the tape is to be used. This adhesive must have good tack as well as creep resistance.

FIG 5. shows the flexible material (such as cardboard or paper) 6 to which the stretcher bars 1 will be adhered by means of the double sided adhesive tape 20. The corners 7 of the flexible material 6 are notched to allow the stretcher bars 1 to bend along a line 8 and meet, without interference from any part of the flexible material 6 from the corners 7. The flexible material 6 is preferably pre-creased along line 8 to allow for easy bending. The centre of the flexible material 6 is perforated to form a rectangle 11 close to line 8. Once the stretching form 40 is assembled, the user is to pull on tab 9, located in one corner of the rectangle 11, and remove the rectangle 11 defined by the perforations 10. The removal of rectangle 11 will allow the canvas 30 to be stretched by the canvas tensioners without interference from flexible material 6.

The flexible material 6 must be stiff, strong, thin and resist tearing. The flexible material 6 must be able to be folded by at least 90 degrees without breaking. Preferably the material is cardboard or paper, but any suitable material will suffice

FIG 6 shows the exploded view of the stretching form 40. The stretcher bars 1 are adhered onto the top of the flexible material 6 using four strips of double sided adhesive tape 20 (herein labelled 20a) placed in a rectangle or other methods of permanent fastening. For example, it will be understood that tape 20a could be a permanent adhesive (instead of double-sided tape) as this set of four strips is typically affixed at the factory. An additional four strips of double sided adhesive tape 20 (herein labeled 20b) are placed on the bottom of the flexible material 6 and wrapped around on to the miters 2. One side of the double sided adhesive tape 20b is left with the release paper intact, to be removed by the user when the canvas 20 is to be positioned.

FIG 7 shows the stretcher form as manufactured and ready for use by the user.. The stretcher bars 1 are pre-positioned and adhered to the flexible material 6 in such a way that they will form a closed frame upon being rotated into their final position (once the canvas 30 is positioned). The double sided adhesive tape 20 is placed along the outer edge of the stretcher form and each end 22 of the tape 20 is wrapped around each miter 2 to allow for the adhesion of the canvas 30 and the corners of the canvas 30 inside the miters 2 before closing the stretching form 40.

FIG 8. shows the stretching form 40 positioned over the back of the canvas 30 (being the side which does not have the picture being displayed) . The release paper on the double sided adhesive tape 20 has been removed and the stretching form 40 is positioned on the canvas 30. The corners 35 of the canvas 30 are then cut and folded to adhere to the edge 22 of the double sided adhesive tape 20b located along the inside of the miters 2.

FIG 9. shows the stretcher bars 1 being rotated into their final position with the U shaped fasteners or staples 5 being inserted into corresponding grooves 3 of two abutting spacer bars 1. The U shaped fasteners or staples must be able to counteract the tension of the canvas 30 and maintain the stretching form 40 in its final position. FIG 10a, 10b, and 10c shows the finished frame once the canvas 30 has been mounted on the stretcher form. The U shaped fasteners or staples 5 are fully inserted. A corner tensioner 12 has been inserted into the corresponding grooves 13 of two abutting spacer bars 1 to maintain tension.

Groove 4 is to be used to center the piece when it is to be to hung on a nail.

In use, the end user places the item to be framed (typically a canvas 30 or other flexible material such as a printed photograph, artwork, illustration, or gallery wrap) on a flat surface such as a table with the image-side down.

The end user takes the stretching form 40, which has been pre-assembled at the factory, and removes the release paper on the double sided adhesive tape 20. The stretching form 40 is then positioned on the canvas 30. The corners 35 of the canvas 30 are then cut and folded to adhere to the edge 22 of the double sided adhesive tape 20b located along the inside of the miters 2.

The stretcher bars 1 are rotated into their final position with the U shaped fasteners or staples 5 being inserted into corresponding grooves 3 of two abutting spacer bars 1. The U shaped fasteners or staples counteract the tension of the canvas 30 and maintain the stretching form 40 in its final position. A corner tensioner 12 is then inserted into the corresponding grooves 13 of two abutting spacer bars 1 to maintain tension.

Once framed, the canvas 30 is lifted and can be hung on wall using a nail or standard picture hanger by means of groove 4.

It will be clear to a person skilled in the art that modifications could be made to the above-identified description without departing from the scope of the invention.

Claims

CLAIMS:Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A modular canvas or material framing system comprising:

(a) four stretcher bars mitered at the ends to be assembled into a rectangular frame for supporting a canvas or material, each stretcher bar having an adhesive strip running lengthwise in the bar at the outer side of the bar so as to face outwardly in the assembled frame and extended to cover the mitered ends of the stretchers.

2. The modular canvas or material framing system according to claim 1 further comprising:

(b) a set of U shaped fasteners applied to grooves supplied on the stretcher to keep the stretching frame in the closed position and to counter act the tension to the canvas upon closing the frame.

3. The modular canvas or material framing system according to claim 1 or 2 wherein each stretcher bar has a pair of grooves which are equally spaced from the centre of the stretcher bar, and

(c) a set of corner tensioners to engage with the grooves of two abutting stretcher bars to maintain tension.

4. The system of claim 1, 2 or 3 wherein a flexible material is used to assemble the stretcher bars in an initial open miter position in such a way that they are secure, square and properly placed relative to each other.

5. The system of claim 4, wherein the flexible material, having four corners, keeps the exposed adhesive on the stretchers from touching the canvas or material before pressing down to allow for easy alignment of the open miter frame, the corners being notched to allow the stretcher bars to bend along a line and meet without interference from any part of the flexible material from the corners.

6. The system of claim 5, wherein the centre of the flexible material is perforated to form a rectangle, said rectangle having a tab in one corner which, when pulled will remove the rectangle defined by the perforations, thereby allowing the canvas to be stretched by the canvas tensioners without interference from the flexible material.

7. The system of claim 1, wherein the canvas or material corners are cut and adhered to the open miter which contains an adhesive strip before the stretching frame is closed thus avoiding unsightly corner folds.