WO1992020535A1

WO1992020535A1 - A framing system

Info

Publication number: WO1992020535A1
Application number: PCT/AU1992/000211
Authority: WO
Inventors: Martin Howard Boscott; Hilary Ingrid Claire Boscott; Anthony Edward Herrell
Original assignee: Martin Howard Boscott; Hilary Ingrid Claire Boscott; Anthony Edward Herrell
Priority date: 1991-05-10
Filing date: 1992-05-08
Publication date: 1992-11-26

Abstract

An improved framing system uses aluminium frame members (10A, 10B) having profiled sections to construct frames on which canvas (14) or other fabric can be mounted for artists' use. A canvas stretching mechanism is used to connect the frame members (10A, 10B) and to expand the frame and thereby tension the canvas (14) or other fabric mounted thereon. Expansion of the frame is controlled by one or more lead screws (25A, 25B) which are journalled in respective frame members and orientated perpendicularly to the plane of the frame. Each lead screw has a wedge-like follower nut (26A, 26B) which engages an oblique surface (21A, 21B) of a bridging member (20) connected to the remainder of the frame. Rotation of the screw causes displacement of its associated frame member relative to the remainder of the frame in the plane of the frame. Canvas (14) is secured to each frame member by capturing it between a bead (15) and associated groove (13) on the frame member. Frames are joined together to form composite frames by clips (31) engaging channels on abutting frame members. A protective cage (36) is provided for storing and transporting multiple frames.

Description

"A FRAMING SYSTEM" THIS INVENTION relates to improvements in framing systems, particularly (but not solely) framing systems for mounting of canvas and other fabrics for artists' use. In one specific application, the invention is directed to a stretcher frame for tensioning canvas or other fabric mounted on the frame, by varying the relative spacings of the frame members.

BACKGROUND ART A common problem encountered with artworks on canvas, particularly large artworks, is the stretching of the canvas with age and application of artists' media.

Such canvas artworks must therefore be retensioned. One simple method of tensioning the canvas is to remove the tacks securing the canvas to its frame, and retack the canvas after tensioning it. However, such a method is time consuming, inaccurate and can easily damage the work of the artist. This basic method is therefore unsuitable for any artwork of substantial value. Tensioning of canvas on a frame has been traditionally performed by driving wedges into the mitre joints of the frame members. The wedges expand the corner joints of the frame and hence the overall size of the frame, thereby tensioning the canvas. Examples of various wedge designs can be found in U.S. patents nos .

3,291,196; 3,133,375 and 3,651,854. When using this method however, there is a danger of striking the canvas and the artist's media thereon. Further, the use of wedges to separate the mitre joints does not normally permit accurate control of the tensioning, and does not provide for selective or independent tensioning along the major orthogonal axes of the frame.

In order to provide more accurate or controlled stretching or tensioning of artists' canvas on frames, various mechanical devices have been proposed and examples of such devices can be found in U.S. patents nos. 3,238,996; 3,625,274; 3,949,702; 4,565,020 and British patent no 1,437,399. The last four patents all use threaded members such as screws which are rotated to control the degree of stretching of the canvas. In all cases however, the threaded members are located in a plane parallel to the plane of the frame, and are positioned close behind the canvas. The threaded members are arranged parallel to the plane of the frame since the desired stretching must be in the plane of the canvas.

The known tensioning devices have several inherent disadvantages. First, it is difficult to obtain clear access to the threaded members. Secondly, due to the orientation and positioning of the threaded members, it is difficult to rotate the threaded members (or the nuts on the threaded members) without touching the back of the canvas itself. For example, in order to rotate the screws in the stretching devices of U.S. patents nos. 3,949,802 and 4,565,020, screw drivers must be placed immediately behind and parallel to the canvas in order to engage the screws. The screw drivers are awkward to use in that position. Further, when rotating the screw driver, there is a great danger that the knuckles of the hand will rub against the back of the canvas and damage the artwork on the front thereof. There is an even greater danger that the screw driver will slip from the screw and seriously damage the canvas.

European patent specification no. 277107 discloses a stretcher frame having a disc eccentrically mounted between the mitred ends of a frame joint. Rotation of the disc causes the ends of the frame elements to separate, thereby expanding the joint and stretching the canvas on the frame. Although the canvas stretching device of European patent specification no. 277107 is relatively easy to access and operate using a screwdriver orientated orthogonally to the frame, it does not readily permit independent tensioning of the canvas along the major orthogonal axes of the frame. Further, the ends of the frame elements must be machined or otherwise modified to accommodate the eccentrically mounted disc. For this reason also, the canvas stretching device of European patent specification no. 277107 is not readily suitable for retrofitting to existing frames.

Traditionally, wooden frames are used for mounting canvas and similar fabrics for artists' use. However, such wooden frames are prone to warping and contraction with age, and are moisture sensitive. Further, the conventional wooden frames are difficult to transport as they require special packaging and mounting. Wooden frames are also difficult to join together securely to form composite frames for large artworks. The wooden frames also do not readily permit secure mounting on walls. Despite these shortcomings of wooden frames, they continue to be used as the conventional framing material due to a lack of suitable alternatives.

It is an object of the present invention to provide an improved framing system which overcomes or ameliorates at least some of the abovedescribed disadvantages, or which at least provides the public with a useful choice.

SUMMARY OF THE INVENTION In one broad form, the present invention provides a stretcher frame suitable for tensioning canvas or other fabric mounted thereon, comprising a plurality of frame members configured to form a generally planar frame; a bridging member adapted to be connected between two of the frame members, the bridging member having a surface portion oblique to the plane of the frame; a threaded member rotatable in at least one of the two frame members and being orientated generally orthogonally to the plane of the frame; a nut member threadedly mounted on the threaded member and having a contact surface portion which, in use, abuts the oblique surface portion, the nut member being held against rotation relative to said one frame member and the bridging member; whereby rotation of the threaded member causes relative movement between said one frame member and the bridging member in a direction parallel to the plane of the frame.

The term "plane of the frame" is intended to refer generally to the plane defined by the canvas or other fabric mounted on the frame, and parallel planes where the context permits.

In the present invention, the threaded member which is used to control the expansion of the stretcher frame, and hence the tensioning of the canvas or other fabric mounted thereon, is orientated perpendicularly to the frame and hence is readily accessible. Due to the wedge or ramp effect created by the oblique surface between the (follower) nut member and the ^• bridging member, displacement of the nut member along its (lead) screw perpendicularly to the plane of the frame will be converted into displacement parallel to the plane of the frame.

Preferably, the frame members form a rectangular frame, and the bridging member is connected between two frame members at their corner junction. The bridging member has two oblique surface portions each having a plane parallel to a longitudinal axis of a respective frame member. A threaded member is journalled for rotation in each of the two f ame members, and each threaded member has a follower nut which has a contact surface portion abutting a respective one of the oblique surface portions of the bridging member. In this manner, the two threaded members permit the two frame members to be independently moved relative to the bridging member in orthogonal directions, thereby permitting the canvas or other fabric on the frame to be tensioned independently in the two major orthogonal axes of the frame. Fine adjustment of the canvas tension can be obtained by controlled rotation of the tensioning screws, and the tension can either be increased or decreased.

Typically, each frame member further comprises a locking screw which is threaded through a portion of the frame member and into the bridging member. The locking screw fixes the frame member relative to the bridging member, and is released during tensioning. The canvas tensioning mechanism serves not only to expand the frame, but also connects the frame members to form the frame. No separate corner joining devices are required.

Preferably, the frame members are constructed from extruded metal section, e.g. aluminium extrusions. In the preferred embodiment, the cross section of each frame member comprises an outer box section for strength and torsional rigidity, and an inner open channel within which part of the canvas stretching mechanism is located. A longitudinal channel is provided between the box section and the inner channel. Canvas or other fabric can be secured to the frame by capturing it between a bead or spline and this channel.

The bridging member may suitably be in the form of a triangular gusset or a L-shaped bracket.

In order that the invention may be more fully understood and put into practice, preferred embodiments thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view of one embodiment of a canvas stretching mechanism used with the framing system of this invention;

Figs. 2 and 3 are sectional views along A-A of Fig. 1 illustrating the operation of the canvas stretching mechanism; Fig. 4 is a perspective view of the canvas stretching mechanism of Fig. 1 applied to a metal frame;

Fig. 5 is a sectional view illustrating the joining of two frames according to the framing system of this invention;

Fig. 6 is a perspective view of a transport mount using the framing system of this invention; and Fig. 7 is a perspective view of the canvas stretching mechanism of Fig. 1 applied to a wooden frame. DESCRIPTION OF PREFERRED EMBODIMENTS The framing system of this invention will be described, by way of example, with reference to its use for mounting canvas, and stretching or tensioning the canvas while mounted on the frame. However, the invention can also be used for mounting and stretching other fabrics on a frame, such as silk, mesh, natural and synthetic fabrics. The term "canvas" is to be interpreted to include such other fabrics where the context permits. Further, the canvas is not limited for use in artworks, but may be utilised in other applications, such as screens, signs, silk screening processes, etc. One embodiment of the framing system of this invention is shown in Figs. 1 to 4. Typically, a rectangular frame is constructed using four mitre-jointed metal frame members. For simplicity and clarity, only the corner junction of two frame members 10A, 10B is shown in Figs. 1 and 4. Each frame member is typically cut from a length of extruded aluminium having a sectional profile specifically designed for mounting canvases. Referring to f ame member 10A by way of example, the frame member comprises an outer box section or closed channel 11, an inner inwardly opening channel 12, and a rearwardly opening channel 13 therebetween.

The box section 12 provides strength and torsional rigidity for the frame while minimising weight. The inner channel 12 serves to locate a canvas stretching mechanism (described below) , and also facilitates the joining of frames, as well as the mounting of frames for display or storage purposes, as described below. Such aluminium frames are strong, lightweight, moisture resistant, stable with age, and non-marking.

The channel 13 is used for securing canvas to the frame. As shown in Fig. 4, the canvas 14 is pulled across the front of the frame and folded over the rear face of each frame member in turn, across the channel 13. The canvas 14 is secured to the frame member by means of a longitudinally extending bead or spline 15 which is inserted into channel 13 in a tight or interference fit. Preferably, the bead or spline 15 is made of rigid material having a small degree of flexibility, such as hard plastics or wood. The channel 13 is provided with a constricted neck portion. Thus, when the bead or spline 15 is tapped into the channel 13, it is squeezed through the restricted neck portion and expands into the base of the channel, thereby providing a keying or locking effect to retain the canvas 14 securely to the frame member 10A.

The channel 13 is relatively deep so that the canvas is pulled substantially into the channel when the bead or spline is tapped into the channel, thereby providing automatic initial tensioning to the canvas when it is secured to the frame. Preferably, the whole length of each spline 15 is pushed in simultaneously so that the canvas is tensioned uniformly along its length. The longitudinal bead or spline also assists in maintaining uniform tension in the canvas along the length of the frame member. Another advantage of the longitudinal bead or spline 15 is that it is able to be removed easily to permit the canvas 14 to be retensioned, or remounted on another frame.

Each frame member also includes a peripheral ridge or upstanding flange 16 on the front side thereof which spaces the canvas 14 from the front face of the frame members . This prevents the canvas from being marked by the frame, and otherwise conceals the frame. Further, the spacing of the canvas from the frame minimises damage to the canvas through forσeable application of artists' media to the canvas.

The framing system also incorporates a canvas stretching mechanism, preferably located at each corner of the frame. One such canvas stretching mechanism is illustrated in Fig. 1 and comprises a bridging or joining member 20 connected between frame members 10A, 10B and located at their mitre junction. The bridging member 20 is typically in the form of an L-shaped gusset having a thickness slightly less than the width of channel 12, thereby permitting the bridging member 20 to be received in a close fit within the right angle channel formed by the mitre junction of channels 12 of frame members 10A, 10B.

Typically, the bridging member 20 is cut from extruded aluminium section, and machined and drilled as required. At each of the two orthogonal sides of the bridging member 20, there is provided a respective surface portion 21A, 2IB which is oblique to the plane of the frame. The oblique surface portions 21A, 2IB may be milled into the bridging member 20. Typically, the oblique surface portions 21A, 2IB are angled at about 40° -50° to the plane of the frame.

The stretching mechanism further comprises tensioning screws 25A, 25B located in respective bores in the two frame members 10A, 10B, as shown in Fig. 1. Each tensioning screw 25A, 25B has a respective nut 26A, 26B threaded thereon and located in the channel portion 12 of a respective frame member 10A, 10B. The height of each nut 26A, 26B is substantially less than the width of channel 12 so that the nut can travel along its associated screw within the channel 12 to some extent.

Each nut 26A, 26B has an oblique face which is juxtaposed with a respective oblique surface portion 21A, 2IB of the bridging member 20. Moreover, each nut 26A, 26B locates within a respective recess in bridging member 20 associated with the oblique surface portions 21A, 2IB, and is thereby prevented from rotating relative to bridging member 20. Each nut 26A, 26B is also prevented from moving relative to bridging member 20 in the direction of its respective frame member, and is prevented from moving relative to its respective frame member in a plane parallel to the frame since it is threaded on its associated screw. The follower nuts 26A, 26B are therefore limited to movement along their lead screws 25A, 25B in a direction perpendicular to the plane of the frame. The canvas stretching mechanism further comprises locking screws 27A, 27B which pass through transverse slots 29A, 29B in frame members 10A, 10B into threaded bores 22A, 22B in the bridging member 20.

In use, the canvas stretching mechanism is located in the corner of the frame, at the rear thereof, as shown in Fig. 4. Each canvas tensioning mechanism serves not only to connect or secure two frame members at their corner junction, but also permits the canvas on the frame to be stretched or tensioned by expanding the frame at its corners. Moreover, the canvas stretching mechanism permits selective stretching in orthogonal directions. That is, either frame member 10A, 10B may be selectively moved outwardly relative to bridging member 20. Thus, if it is desired to tension the canvas in the direction parallel to frame member 10B, frame member 10A will be moved outwardly relative to bridging member 20. To achieve the tensioning in this direction, locking screw 27A is first unscrewed slightly to permit frame member 10A to move relative to bridging member 20 in the direction of slot 29A. The tensioning screw 25 is then rotated, for example by a screw driver or Allen key 30 (Fig. 2). The tensioning screw 25A acts as a lead screw, and its associated nut 26A functions as a follower nut moving axially along the lead screw as it is rotated.

As the nut 26A moves along screw 25A from the position shown in Fig. 2 to that shown in Fig. ^' 3, the wedge or ramp effect created by the abutting oblique surfaces of nut 26A and portion 21A of bridging member 20 will cause relative displacement between the frame member

10A and the bridging member 20. As bridging member 20 is still secured to frame member 10B, the rotation of tensioning screw 25A has the effect of expanding the joint between the two frame members 10A, 10B. Such expansion of the corner joint will tension the canvas 14 in the direction parallel to frame member 10B. Once the required degree of tensioning has been achieved, locking screw 27A is tightened to prevent any further relative movement between frame member 10A and bridging member 20.

Similarly, the canvas 14 can be tensioned in a direction parallel to frame member 10A by moving frame member 10B relative to bridging member 20, and hence expanding the corner joint in that direction.

The abovedescribed canvas tensioning mechanism permits the mitre joint of the two frame members 10A, 10B to be selectively expanded in either of the longitudinal directions of the frame members, thereby providing independent tensioning of the canvas along the major orthogonal axes of the frame. It is to be noted that although the tensioning forces are applied parallel to the plane of the frame, the tensioning screws are perpendicular to the frame, permitting safe and easy access to the screws. Further, the screw-type adjustment of the canvas tension permits small and accurate adjustments of canvas tension to be made.

The use of profiled frame members, such as extruded aluminium frame members 10A, 10B illustrated in Fig. 1, has other attendant advantages. For example, as shown in Fig. 5, such frame members can be secured together with their outer faces in abutment by using adjustable clips 31 engaging the channels 12 in the frame members. (For clarity, the frame members are shown joined without canvas thereon. However, it will be understood the frame can be joined together with or without canvas on the individual frames.) Each clip 31 comprises two clip members 32, 33 having U-shaped ends and which are secured together by a bolt and wing nut combination 34. The provision of a slot 35 (Fig. 6) in one of the clip members 33 enables the spacing between the ends to be varied.

The use of profiled frame members in the framing system also facilitates the mounting of the frames, either for display, storage or transport purposes. A mounting cage 36, illustrated in Fig. 6, can be used for mounting a plurality of frames for transport or storage. The mounting cage 36 comprises a generally box-shaped frame 37 having a plurality of top rails 38 and bottom rails 39 as shown. The rails 38, 39 may be in the form of square tubular rails. Each frame may be suspended from a respective top rail 38 by two or more clips 40, as shown in Fig. 6. Similar clips 40 may be used in conjunction with variable length clips 31 to secure the bottom frame member of each frame to a respective bottom rail 39.

The abovedescribed arrangement permits one or more frames to be transported safely and conveniently. The frames are spaced within the cage 36, which protects the frames and absorbs any impact. Such an arrangement reduces the cost of transporting valuable artworks.

Despite the advantages of using extruded aluminium frame members, many traditionalists prefer to use wooden frames. According to another aspect of the framing system of this invention, the canvas stretching mechanism of Fig. 1 is adapted for use with wooden frames. As illustrated in Fig. 7, a canvas stretching mechanism comprises a bridging member 42, tensioning screws 43A, 43B with associated nuts (not shown) of similar shape to nuts 26A, 26B of Fig. 1, together with locking screws 44A, 44B. These components are fitted to a pair of short channel sections 45A, 45B having mitred ends forming a corner joint. Each channel section 45A, 45B is affixed, by threaded fastener or otherwise, to a respective wooden frame member 46A, 46B. The wooden frame members 46A, 46B also have respective longitudinal grooves in which the canvas is secured by means of a bead or spline.

The canvas stretching device serves not only to join the wooden frame members 46A, 46B to form a corner joint, but also permits the joint to be selectively expanded in either one of two orthogonal directions. The operation of the canvas tensioning device of Fig. 7 is similar to that of Fig. 1.

The canvas stretching device of Fig. 7 can be retrofitted to existing wooden frames with little, if any, alteration of the existing frame and canvas. It will therefore be apparent to those skilled in the art that the canvas stretching mechanism of this invention is applicable not only to new frames, but also to existing frames of wood or other materials.

The foregoing describes only some embodiments of the invention and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention as defined in the following claims. For example, the framing system can include canvas tensioning devices in which the bridging member 20 is replaced or supplemented by a bridging member extending between parallel frame members on opposite sides of the frame. For heavier or larger frames, a corner member (not shown), such as a disc-like or L-shaped insert, may be inserted within the box sections 11 of frame members 10A, 10B across their mitre junction.

Claims

CLAIMS :

A stretcher frame suitable for tensioning canvas or other fabric mounted thereon, comprising a plurality of frame members configured to form a generally planar frame; a bridging member adapted to be connected between two of the frame members, the bridging member having a surface portion oblique to the plane of the frame; a threaded member rotatable in at least one of the two frame members and being orientated generally orthogonally to the plane of the frame; a nut member threadedly mounted on the threaded member and having a contact surface portion which, in use, abuts the oblique surface portion, the nut member being held against rotation relative to said one frame member and the bridging member; whereby rotation of the threaded member causes relative movement between said one frame member and the bridging member in a direction parallel to the plane of the frame.

2. A stretcher frame as claimed in claim 1, wherein the two frame members are orthogonal and form a corner junction across which the bridging member is connected, and further wherein the bridging member has two oblique surface portions each having a plane parallel to a longitudinal axis of respective one of the two frame members, and further wherein there are two threaded members each rotatable in a respective one of the two frame members and each having a respective nut member threadedly mounted thereon, each nut member having a contact surface portion abutting a respective one of the oblique surface portions, whereby the two frame members may be moved independently relative to the bridging member in respective orthogonal directions.

3. A stretcher frame as claimed in claim 2 wherein the contact surface portion of each nut member is parallel to its abutting oblique surface portion of the bridging member.

4. A stretcher frame as claimed in claim 3, wherein each oblique surface portion is at an angle of between 40° and 50° to the plane of the frame.

5. A stretcher frame as claimed in claim 2, wherein each oblique surface portion of the bridging member partly defines a respective recess in the bridging member, each nut member being located within a respective recess of the bridging member and thereby prevented from rotating relative to the bridging member.

6. A stretcher frame as claimed in claim 2, wherein each of the frame members has an open channel formation extending longitudinally thereon and opening inwardly of the frame, a respective edge portion of the bridging member and a respective nut member being located within the channel formation.

7. A stretcher frame as claimed in claim 6, wherein each of the frame members has a slot in a side wall of its channel formation through which a locking screw is rotatably located, each locking screw being threaded into a respective threaded bore in the bridging member, whereby each frame member can be fixed relative to the bridging member by its locking screw.

8. A stretcher frame as claimed in claim 1, wherein each frame member has a longitudinal channel opening on the rear face thereof, and an associated bead or spline member adapted to be inserted in the longitudinal channel in a tight or interference fit, whereby the canvas or fabric can be secured to the frame by capturing it between the bead or spline member and the channel.

9. A stretcher frame as claimed in claim 8, wherein the frame members are formed of extruded aluminium and each frame member has a ridge extending longitudinally along the outer front edge thereof for spacing the canvas or fabric from the front face of the frame .

10. An expandible corner joint assembly for fitting to frame members of a generally planar frame to form a stretcher frame, the corner joint assembly comprising a pair of intermediate frame members each of which is adapted to be fixed to a respective one of a pair of the frame members adjacent a corner junction thereof, a bridging member connected between the intermediate members, the bridging member having at least one surface portion oblique to the plane of the frame; a threaded member rotatable in at least one of the intermediate frame members and being orientated generally orthogonally to the plane of the frame; a nut member threadedly mounted on the threaded member and held against rotation relative to said one intermediate frame member and having a contact surface portion which abuts the oblique surface portion; whereby rotation of the threaded member causes relative movement between the abutting surface portions of the nut member and the bridging member to thereby cause relative movement between the frame member connected to said one intermediate frame member and the bridging member in a direction parallel to the plane of the frame.

11. An expandible corner joint assembly as claimed in claim 10, wherein the bridging member has two oblique surface portions each having a plane parallel to a longitudinal axis of a respective one of the two intermediate frame members, and further wherein there are provided two threaded members each rotatable in a respective one of the two intermediate plane members and each having a respective nut member threadedly mounted thereon, each nut member having a contact surface portion abutting a respective one of the oblique surface portions, whereby the frame members connected to the two intermediate frame members may be independently moved relative to the bridging member in respective orthogonal directions.

12. An expandible corner joint assembly as claimed in claim 11 when fixed to wooden frame members, wherein the intermediate frame members are of metal construction.

13. An expandable frame suitable for tensioning canvas or other fabric mounted thereon, comprising a plurality of frame members configured to form a generally planar frame; a lead screw journalled for rotation in a frame member and orientated generally perpendicularly to the plane of the frame; a follower nut on the lead screw having a portion of its surface abutting a surface portion of a member which is fixed relative to the remainder of the frame and whose movement perpendicularly to the plane of the frame is restricted, at least one of the surface portions being a planar surface angled obliquely to the plane of the frame to form a wedge-like formation; whereby rotation of the lead screw causes displacement of the frame member relative to the remainder of the frame in the plane of the frame.

14. A housing for holding a plurality of frames for storage or transport, each frame being comprised of frame members at least an opposed pair of which each have a longitudinally extending channel therealong, the housing comprising a framework having a plurality of pairs of vertically aligned top and bottom rails, and a plurality of clip members for securing the top and bottom frame members of each frame to a pair of top and bottom rails respectively, each clip member having hook formations at its opposite ends for engaging respectively a rail and a channel of a frame member, wherein at least one of the clip members is of adjustable length.