Abstract:
A canvas stretching assembly has adjustable stretching bars connecting in an end-to-end configuration that allow for the stretching of a canvas, even after the canvas is mounted thereon, with the degree of stretching being adjustable in multiple directions. The canvas stretching assembly, when disassembled, may be compactly stored, which is especially appreciated for shipment purposes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Benefit of U.S. Provisional Application for Patent Ser. No. 61/282,531 filed on Feb. 25, 2010, which is incorporated herein by reference, is hereby claimed. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to canvas stretching apparatuses and assemblies for stretching canvases, and is more particularly directed to an adjustable canvas stretching assembly having adjustable stretching bars. 
       BACKGROUND OF THE INVENTION 
       [0003]    Use of stretched canvas as a preferred medium for painting is well known in the art. However, traditional methods, apparatuses, and assemblies for stretching the canvas to a desired tightness, whether before or after painting or other inscription of an image thereupon, often require specialized tools and skills, and therefor specialized personnel. Accordingly, proper stretching of the canvas to a desired tightness can be both time consuming and expensive. 
         [0004]    For example, purchasers of (unframed) canvases having artwork inscribed thereon are often obligated to retain professional framing services to stretch the canvas to the desired tightness on a frame base or stretching assembly having stretching members or bars, which may themselves form a frame base. Subsequently, the canvas may be hung on a wall or other structure by hanging the frame base or stretching assembly with the stretched canvas thereupon. Alternatively, once the canvas is stretched on the assembly, a decorative frame moulding may be connected or mounted on the assembly to provide a desired aesthetic effect. In either case, the canvas must be transported to the framing service, stretched and framed, and then transported back to the purchaser on the frame base. Obviously, this process, in addition to the cost of the stretching and framing, involves the cost, and time, of transport of the canvas to the framing service and of the canvas on the frame base back to the purchaser. These costs can be prohibitive, especially for larger canvases and/or for situations where the framing service is situated at long distance from the purchaser. 
         [0005]    Accordingly, there is a need for an improved canvas stretching assembly. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore a general object of the present invention to provide an improved canvas stretching assembly for a canvas. 
         [0007]    An advantage of the present invention is that the degree of stretching of the canvas is adjustable, even after the canvas is mounted thereon. 
         [0008]    Another advantage of the present invention is that the degree of stretching is adjustable in multiple directions. 
         [0009]    Still another advantage of the present invention is that the canvas stretching assembly is of simple construction. 
         [0010]    Yet another advantage of the present invention is that the canvas stretching assembly, when disassembled, may be compactly stored, which is especially appreciated for shipment purposes. 
         [0011]    Still a further advantage is that the canvas may be stretched using the canvas stretching assembly without special skills or recourse to specialized tools. 
         [0012]    As yet another advantage, the stretching assembly may be used, once the canvas is stretched thereupon, as a frame base to hang the canvas, with optional attachment of decorative mouldings to form a decorative frame. 
         [0013]    In one aspect, the present invention provides an adjustable canvas stretching assembly for stretching a canvas, the stretching assembly comprising:
       first, second, third, and fourth elongate stretching bars of generally rectangular hexahedron shape having, extending longitudinally from respective first end faces to opposed respective second end faces, opposed respective outer and inner faces extending adjacently between generally opposed rear and front faces, each first end face having at least one end channel extending axially from the first end face inwardly into the stretching bar along an axis defined by the stretching bar and an adjustable bolt disposed thereon and axially adjustable rear and forth along the axis by rotation of the bolt, each inner face having at least one inner channel extending inwardly into the stretching bar from the inner face and generally perpendicular the axis adjacent the respective second end face, the first and second stretching bars being of a first length and the third and fourth stretching bars being of a second length; and   a plurality of connector members, each connector member being snugly insertable into an inner channel of one stretching bar and into the end channel of an adjacent stretching bar to connect, in an assembled configuration for the assembly, the first and second stretching bars generally perpendicularly to the third and fourth stretching bars with each first end face of each stretching bar connected to the inner face of an adjacent stretching bar and abutting against a head of the bolt, with the front bar faces defining a front side of the assembly and the rear faces defining a rear side of the assembly for attachment of the canvas thereto, the end channels and inner channels being positioned for registration of the second end face of each stretching bar with the outer face of an adjacent stretching bar connected thereto, wherein the stretching bars may be drawn away from one another when connected by rotating the bolts to stretch the canvas tightly across the front side of the assembly.       
 
         [0016]    Preferably, each first end face has two end channels and each inner face has two corresponding inner channels. 
         [0017]    In one embodiment, each rear face has a slot extending inwardly therefrom and oriented generally axially therealong, and, for each stretching bar, the assembly includes a corresponding slot member, each slot and corresponding slot member being sized and shaped for snug and retaining insertion of the corresponding slot member into the slot, for gripping the canvas therebetween. 
         [0018]    Conveniently, each slot extends axially between the first and second end faces of the corresponding stretching bar. 
         [0019]    In one embodiment, the assembly further includes an elongate cross bar extending between the first and second stretching bars and having a length substantially equal to the second length, the cross bar having at least one cross bar channel extending generally axially therein at each one of opposed cross bar ends and connector members, each connector member being snugly insertable into a corresponding one of the cross bar channel and into a corresponding frame cross bar channel extending inwardly from the inner face of a corresponding one of the first and second stretching bars and being disposed generally centrally thereupon to connect, in the assembled configuration, the cross bar generally perpendicularly to the first and second stretching bars. 
         [0020]    Typically, each one of the cross bar end includes a corresponding adjustable cross bar bolt disposed thereon and axially adjustable rear and forth along a cross bar axis by rotation of the cross bar bolt, in the assembled configuration, the cross bar connecting to the first and second stretching bars with the inner face of each one of the first and second stretching bars connecting to a corresponding cross bar end and abutting against a head of the cross bar bolt. 
         [0021]    Conveniently, the cross bar is a first cross bar, and the assembly further includes a second elongate cross bar extending between the third and fourth stretching bars and having a length substantially equal to the first length, the second cross bar having at least one cross bar channel extending generally axially therein at each one of opposed cross bar ends and connector members, each connector member being snugly insertable into a corresponding one of the cross bar channel and into a corresponding frame cross bar channel extending inwardly from the inner face of a corresponding one of the third and fourth stretching bars and being disposed generally centrally thereupon to connect, in the assembled configuration, the second cross bar generally perpendicularly to the third and fourth stretching bars. 
         [0022]    Typically, each one of the second cross bar end includes a corresponding adjustable cross bar bolt disposed thereon and axially adjustable rear and forth along a cross bar axis by rotation of the cross bar bolt, in the assembled configuration, the second cross bar connecting to the third and fourth stretching bars with the inner face of each one of the third and fourth stretching bars connecting to a corresponding second cross bar end and abutting against a head of the cross bar bolt. 
         [0023]    Typically, each one of the first and second cross bars has a generally centrally recess formed thereon for receiving an intersecting section of the other one of the first and second cross bars at an intersection thereof when in the assembled configuration. 
         [0024]    Conveniently, each one of the cross bar bolt has a perforating protrusion extending axially from the head of the cross bar bolt. 
         [0025]    In one embodiment, the first and second lengths are substantially equal to one another. 
         [0026]    Other objects and advantages of the present invention will become apparent from a careful reading of the detailed description provided herein, with appropriate reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Further aspects and advantages of the present invention will become better understood with reference to the description in association with the following Figures, in which similar references used in different Figures denote similar components, wherein: 
           [0028]      FIG. 1  is a partially exploded rear perspective view of an adjustable stretching assembly for a stretching a canvas, prior to connection of the canvas thereto, in accordance with an embodiment of the present invention; 
           [0029]      FIG. 1   a  is a rear perspective view of the assembly shown in  FIG. 1 , showing the canvas framed thereupon; 
           [0030]      FIG. 2  is an exploded rear plan view of the assembly shown in  FIG. 1 ; 
           [0031]      FIG. 3  is a partial exploded perspective view of the assembly shown in  FIG. 1 ; 
           [0032]      FIG. 4  is a partial enlarged rear plan view showing adjacent stretching bars of the assembly of  FIG. 1  with the stretching bars retracted; and 
           [0033]      FIG. 4   a  is a partial enlarged rear plan view showing adjacent stretching bars of the assembly of  FIG. 1  with the stretching bars extended. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    With reference to the annexed drawings the preferred embodiments of the present invention will be herein described for indicative purpose and by no means as of limitation. 
         [0035]    Reference is now made to  FIGS. 1 ,  1   a ,  2 ,  3 ,  4 , and  4   a . In  FIG. 1 , there is schematically shown an embodiment of an adjustable canvas stretching assembly, shown generally as  10  for attachment and stretching, in an assembled end-to-end configuration  80 , of a canvas  12  thereupon to a desired tightness. As shown best in  FIG. 2 , the assembly  10  consists of, preferably identical, first and second elongate members or stretching bars  14  and, also preferably identical, third and fourth elongate members or stretching bars  16 . All of the stretching bars  14 ,  16  are rectangular hexahedrons in shape, having inner and outer faces  18 ,  20  and adjacent rear and front faces  22 ,  24  extending adjacently therebetween, the inner and outer faces  18 ,  20  and rear and front faces  22 ,  24  extending longitudinally from a first end face  26  to a second end face  28  of each stretching bar  14 ,  16 . The first and second stretching bars  14  are of an identical first length between the respective end faces  26 ,  28  thereof, whereas the third and fourth stretching bars  16  are of an identical second length between their respective end faces  26 ,  28 . It should be noted, however, that the first and second lengths may also be the same, notably where the assembly  10  is intended for stretching an essentially square canvas. 
         [0036]    As shown in  FIGS. 2 ,  3 ,  4 , and  4   a , each first end face  26  has at least one axial end bore or channel  30  extending axially from the first end face  26  inwardly into the stretching bar  14 ,  16  along an axis X defined by the stretching bar  14 ,  16 , i.e. generally parallel faces  18 ,  20 ,  22 ,  24  and perpendicular to the end faces  26 ,  28 . Each first end face  28  also has an adjustable threaded bolt  32  mounted thereon, preferably in a threaded socket  34  extending axially into the stretching bar  14 ,  16 . The bolt  32  is axially adjustable back and forth along the axis X by rotation thereof to move a head  36  of the bolt  32  away from or towards the first end face  26 . Similarly, each inner face  18  has, adjacent the respective second end face  28 , at least one inner channel  38  extending inwardly into the stretching bar  14 ,  16  from the inner face  18  and generally perpendicular the axis X, i.e. perpendicular to the inner face  18 . 
         [0037]    The end channels  30  and inner channels  38  are positioned such that a connector member  40 , as a dowel pin or the like, may be snugly and grippingly inserted therein to connect the first end faces  26  and inner faces  18  of the first and second stretching bars  14  to, respectively, the inner faces  18  and first end faces  26  of the third and fourth stretching bars  16  to place the assembly  10 , from a disassembled configuration  82 , into an assembled configuration  80 . Specifically, for the assembled configuration  80 , each connector member  40  is inserted, on a first connector end  42  thereof into an end channel  30  of first or second stretching bar  14  and into an, on an opposite second connector end  42  thereof, into an inner channel  38 . Further, the channels  30 ,  38  and connector members  40  are sized and, preferably cylindrically, shaped such that the connector members  40  fit snuggly into the channels  30 ,  38  and that connected adjacent stretching bars  14 ,  16  may be pushed towards one another until the inner face  18  of each stretching bar  14 ,  16  abuts against the head  36  of bolt  32  of the connected adjacent stretching bar  14 ,  16  and the head  36  abutting against the first end face  26 . 
         [0038]    The channels  30 ,  38  are further positioned such that when the stretching bars  14 , 16  are connected by connector members  40  in assembled configuration  80 , the second end face  28  of each stretching bar  14 ,  16  is in planar registration with the outer face  20  of the connected adjacent stretching bar  14 ,  16 . Thus, in the assembled configuration  80 , the stretching bars  14 ,  16  are connected together, with the front faces  24  defining a front side  24  of the assembly  10  and the rear faces  22  defining a rear side  22  of the assembly. Preferably, to provide enhanced stability and prevent any rotation of the stretching bars  14 ,  16  about respective connector members  40 , there are two end channels  30  on each first end face  26  and two corresponding inner channels  38  on each inner face  18 , thus ensuring that each stretching bar  14 ,  16  is connected by two connector members  40 . Preferably, the channels  30 ,  38  are positioned diagonally opposite one another, thus ensuring that the stretching bars  14 ,  16  are connected to one another proximal both the rear face  22  and front face  24 . The bolt  32  and bolt socket  34  are situated proximal the rear face  22  to ensure that the bolt may be turned and accessed from the rear face  22  when the canvas is connected to the assembly  10 . 
         [0039]    As best shown in  FIGS. 4 and 4   a , once connected, each stretching bar  14 ,  16 , on the first end face  26  thereof, can be moved away from an adjacent connected stretching bar  14 ,  16 , by rotating the head  36  in a first direction, for example with a wrench or the like (not shown). Conversely, if it is desired to decrease the space between two adjacent stretching bars  14 ,  16 , when the inner face  18  of one stretching bar  14 ,  16  is abutting the head  36 , one has only to rotate the bolt in a second direction to move the head  36  closer to the first end face  26  and to push the stretching bars  14 ,  16  towards one another until the inner face  18  again abuts the head  18 . Thus, the bolts  32  provide adjustable spacing of the stretching bars  14 ,  16  for adjustable stretching of the canvas when connected to the assembly  10 . 
         [0040]    Turning now to the method of using the assembly  10 , when it is desired to stretch a canvas  12  with the assembly  10 , the assembly  10  is placed in the assembled configuration  80 , as described above. The canvas  12  is then connected to the rear face  22  of each stretching bar  14 ,  16 , which together form the rear face  22  of the assembly  10 . Preferably, however, the canvas  12  is connected to the assembly  10  in assembled configuration  80  with each of the stretching bars  14 ,  16  in a retracted configuration  84  in which the bolts  32  are fully retracted with the heads  36  abutting against the first end face  26  of their respective bars  14 ,  16  and with the inner face  18  of the adjacent bar  14 ,  16  abutting the head  36 . By rotating the heads  36  in the first direction, the user may force the stretching bars  14 ,  16  to be extended away from one another by extension of the bolts  32  until the canvas  12  is stretched to a desired tightness, in the view of the user, across the front face  24  of the assembly  10 , with a display portion  100 , shown in dotted lines in  FIG. 1 , visible and stretched across the front side  24  of the frame  10 . Typically, the display portion  100  contains the image inscribed on the canvas  10 . Alternatively, if the user finds that the canvas  12  is stretched too tightly, the user may rotate one or more of the heads  36  in the second direction, thus enabling one or more of the stretching bars  14 ,  16  to be pushed inwardly towards another stretching bar  14 ,  16  to stretch the canvas  12  less tightly. Conveniently, as each stretching bar  14 ,  16  may be drawn away or moved closer toward an adjacent bar  14 ,  16 , adjustment of the stretching when assembly  10  is assembled may be effected in any of the four axial directions of the stretching bars  14 ,  16 . In order to minimize contact between the canvas  12  and front side  24  when the canvas  12  is stretched tightly thereacross, each stretching bar  14 ,  16  preferably has a ridge or lip  58  protruding outwardly from the front face  22 , adjacent to and in planar registration with the outer face  20 . 
         [0041]    Referring now to  FIGS. 1 and 1   a , the canvas  12  may be connected, to the assembly  10  by connecting the canvas  12  to the rear face  22  of each stretching bar  14 ,  16  with any conventional connector, such as screws, tacks, staples, glue, or the like. However, to minimize the need to perforate the canvas  12 , there is provided a slot  52  extending inwardly from the rear face  22  of each stretching bar  14 ,  16  and a corresponding slot member  54  for connecting the canvas  12  to the rear faces  22 . The slot members  54  and slot  52  are sized and shaped, preferably rectangularly, for snug and retaining insertion of the slot member  54  into the slot  52  that typically extends axially between the first and second end faces  26 ,  28  of each stretching bar  14 ,  16 . Thus, to connect the canvas  12  to the assembly  10 , preferably in assembled configuration  80  with all bars  14 ,  16  in retracted configuration  82 , the canvas  12  is draped across or seated into each slot  52 . The respective slot member  54  is then pushed, or wedged, into the slot  52  on each stretching bar  14 ,  16  to grip the canvas  12  within the slot  52  and connect the canvas  12  to the assembly  10 , minimizing need for nails, staples, or the like which perforate the canvas  12 . The slots  52  and slot members  54 , are further sized and shaped such that when the slot members  54  are inserted into the slots  52  with the canvas  12  held therebetween, the slot members  54  in slots  52  extend generally planarly in register with the rear faces  22 . 
         [0042]    Once the canvas  12  is connected to the assembly  10  and stretched to the desired tightness, as described above, the canvas  12  may be hung on a wall or other surface, typically with the rear face  22  connected to and facing the surface. Thus, the assembly  10  in assembled configuration may be used as a frame base  10  for hanging the canvas  12 . Additionally, if desired, decorative mouldings may be connected to the stretching bars  14 ,  16 , once the canvas  12  is connected thereto and stretched, to provide a decorative frame for the canvas  12 . 
         [0043]    Reference is now made to  FIGS. 1 ,  2 , and  3 . Optionally, for larger canvases  12  and longer stretching bars  14 ,  16 , the assembly  10  may have additional elongate first and second cross members or bars  60 ,  62  which are connectable, respectively, to the first and second stretching bars  14  and the third and fourth stretching bars  16  in the assembled configuration  80 . The first cross bar  60  is substantially equal in length to the third and fourth stretching bars  16 , and more specifically generally equal to the distance between the first and second stretching bars  14 , and the second cross bar  62  is substantially equal in length to first length of the first and second stretching bars  14 , and more specifically generally equal to the distance between the third and fourth stretching bars  16 . Each cross bar  60 ,  62  has at least one, and preferably two, cross bar channels  64  at opposed cross bar ends  70  and extending generally axially therein, with each stretching bar  14 ,  16  having corresponding frame cross bar channels  66  positioned generally centrally thereupon and extending inwardly from the corresponding inner face  18  thereof and generally perpendicularly from the axis X thereof. Thus, as the assembly  10  is assembled the cross bars  60 ,  62  may be connected to the stretching bars  10  using connector members  40  in channels  64 ,  66  in the same fashion as for connector members  40  in channels  30 ,  38 . As the cross bar channels  66  are disposed generally centrally on the stretching bars  14 ,  16  the cross bars  60 ,  62  generally extend across the center of the assembly  10  when assembled. Each of the cross bars  62 ,  64  has a centrally situated recess  68 , well known in the art, which brace the cross bars  62 ,  64  at their intersection. Optionally, there may also be a bolt  32  and bolt socket  34  at each cross bar end  70 , which may be used when adjusting the frame  10  in the same fashion as for stretching bars  14 ,  16 . Further, to provide greater stability of the cross bars  62 ,  64  and alignment, the bolt  32  for the cross bars  62 ,  64  may have a perforating protrusion  102 , for example a pointed stud  36 ′ or the like, extending axially from the head  36  of the bolt  32  for perforating the stretching bars  14 ,  16  as the bolt  32  is extended. 
         [0044]    The stretching bars  14 ,  16  and cross bars  60 ,  62  are preferably constructed of wood, although other materials, such as plastic may be envisaged. The connector members  40 , bolt  32 , and bolt socket  34  are preferably constructed of metal. However, once again, alternative materials, such as rigid plastics, may be deployed. Further, while channels  30 ,  38 ,  64 ,  66  and connector members  40  are preferably cylindrical, any shape and size that allows for snug and gripping retention of connector members  40  in channels  30 ,  38 ,  64 ,  66  may be deployed. 
         [0045]    Although the present frame assembly has been described with a certain degree of particularity, it is to be understood that the disclosure has been made by way of example only and that the present invention is not limited to the features of the embodiments described and illustrated herein, but includes all variations and modifications within the scope and spirit of the invention as hereinafter claimed.