Abstract:
Joint separating apparatus comprises clamping means for releasably securing the apparatus to one element of a joint between it and a second element of the joint, and pressure means actuable to exert pressure on the second element to separate the elements at least partially.

Description:
BACKGROUND OF THE INVENTION 
     This is a file wrapper continuation of application Ser. No. 08/273,011, filed Jul. 8, 1994, now abandoned. 
     This invention relates to an apparatus for the separation of joints and particularly, but not exclusively, the invention is concerned with an apparatus for the separation of nailed joints between wooden elements. 
    
    
     SUMMARY OF THE INVENTION 
     In accordance with the invention there is provided a joint separating apparatus comprising clamping means for releasably securing the apparatus to one element of a joint between it and a second element of the joint, and pressure means actuable to exert pressure on said second element to separate said elements at least partially. 
     In such an apparatus the reactive force generated by the pressure means when actuated to exert pressure on said second element of the joint is transmitted through the clamping means of the apparatus to said first element of the joint. 
     The apparatus conveniently comprises a pair of arms each of which has a clamping member provided thereon and at least one of which can be moved towards the other whereby a first element of a joint may be releasably clamped between opposed surfaces of the clamping members when a clamping force is applied between them. Preferably a fluid pressure actuated piston and cylinder assembly is connected between the pivotally connected arms and is operable to initiate relative movement between the clamping members carried by the arms. Each of the clamping members may comprise a clamping plate mounted on a respective arm and being provided with a gripping surface for engagement with a first element of a joint. 
     The pressure means preferably comprises a fluid pressure actuated ram carried by each of the arms of the apparatus. Each of the rams conveniently has a cylinder thereof secured to the respective arm and a piston rod having a presser plate at one or both of its free ends for engagement with a said second element of the joint. 
     Each of the fluid pressure actuated rams and the piston and cylinder assemblies conveniently comprises a pneumatic device operable by compressed air. 
     Each of the rams is conveniently mounted on a respective arm of the apparatus and is capable of extension in a direction which is normal to the plane in which relative movement of the clamping members occurs. Thus for example if it is desired to separate two elements of a nailed joint wherein a first joint element comprises a wooden block and a second joint element comprises a wooden board nailed to one end of the block, the apparatus of the invention may initially be secured to the block by effecting relative movement between the opposed clamping members in a generally horizontal plane to clamp opposite sides of the block of the joint therebetween, clamping pressure being maintained by the piston and cylinder assemblies. Vertically directed pressure may then be applied to the board of the joint by one or both rams, to press the board away from the end of the block to which it is nailed. 
     Joint separating apparatuses constructed as described above may be utilised to effect an initial separation of a nailed joint subsequent to which a cutting or shearing element may be insertable into the space between the separated elements of the joint for cutting the nails. 
     Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of joint separating apparatus in accordance with the invention; and 
     FIGS. 2 to 4 are respectively rear, plan and side views of the apparatus shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The joint separating apparatus illustrated in the drawings comprises a frame 1 suspended by a system of coil springs 2 from a carrier 3 secured at each of its ends to a joining bracket 4 of pulley wheels 5 movable along a track (not shown). The track may be fixed or movable, that is to say it may be rotatable about a fixed support. The carrier 3 supports a downwardly extending rod 6 which passes through an upper plate 7 and is attached to a collar 8 on which the plate 7 seats. Upstanding from and secured to the frame 1 is a sleeve 9 through which the rod extends. Secured to the outer circumference of the sleeve 9 is a lower plate 11. The coil 2 springs interconnect the plates 7, 11 and permit relative vertical movement of the frame 1 relative to the rod 6. The coil springs 2 also enable the frame 1 to be rotated about the rod 6 for ease of manoeuvrability. Handles 12 are provided on the rear side of the frame. 
     The frame 1 supports a pair of opposed clamping members 14, 15 each of which is carried by an upwardly extending arm 16, 17 respectively of the frame. The arm 17 is fixed to the frame and the arm 16 is mounted for pivotal movement about a pivot 18 towards and away from the arm 17 by a fluid actuated piston and cylinder assembly 19. The piston of the assembly 19 is pivotally connected by a pin 21 to an extension piece 22 of the arm 16. The cylinder of the assembly 19 is pivotally connected by a pin 23 to an upright 24 of the frame 1. 
     The assembly is conveniently actuated by compressed air and may be powered to move the arm 16 either towards or away the arm 17. Compressed air is fed selectively to one or other ends of the cylinder of the assembly 19 via pipes 25a/25b connected to a three way valve operated by a control lever 28, supported from a plate 29 secured to the frame 1. Compressed air from an airline passes through the valve and thence to one of the pipes 25a, 25b. 
     The free end of each arm 16, 17 carries a respective clamping member 14, 15. Each clamping member includes a clamping plate 34, 35 having a gripping surface which may be suitably toothed or otherwise serrated to enhance the gripping of one element of a joint to be separated. 
     Each clamping member carries a double-acting fluid operated ram assembly including a vertically mounted piston 36, 37 which moves within a complementary cylinder secured to the respective member. The upper and lower surfaces of each piston can stand proud of the respective upper or lower surface of the clamping member. Each piston 36, 37 carries a &#34;U&#34; shaped presser plate 38, 39 for engagement with a second element of a joint to be separated. Thus the pressure exertable by each presser plate 38, 39 of the two ram assemblies is in a direction normal to the plane in which the clamping members grip the first element of the joint. The permitted vertical movement of the presser plates may be of the order of 12 mm. 
     The double acting pistons 36, 37 of the ram assemblies are moved by compressed air admitted selectively or sequentially to the cylinder via pipes 41 connected to an air line 31 through a three-way valve of a pressure enhancer 40 operated by a control lever 42 supported from a plate 43 secured to the frame 1. The enhancer 40 increases the air line pressure by, for example, a factor of three. A support bracket 48 for the pipes 25A, 25B and 41 is secured to the frame 1. 
     Mounted one to each opposing side face of the clamping members 14, 15 are fulcrum plates 44, 45 to assist alignment of a manually operated saw used to cut through or shear nails exposed by operation of the ram assemblies. Spacing members 46, 47 are provided to assist proper location of the clamping members relative to the elements to be separated. 
     In use, the joint separating apparatus may be utilised, for example, to separate two elements of a joint comprising a wooden board nailed to an upper end of a wooden block. In such an application the apparatus would initially be secured to opposite sides of the block by positioning the surfaces 34, 35 of the clamping members 14, 15 adjacent such opposite sides and then powering the piston and cylinder assembly 19 through operation of the control lever 28 to bring the gripping surfaces 34, 35 into clamping engagement with opposite sides of the block. In this position, the pistons 36, 37 are positioned adjacent opposite sides of the block and below the boards nailed to the upper ends of the block whereby upon extension of the pistons 36, 37 from the cylinders of the assemblies, the respective presser plates 38, 39 force the board upwardly from the upper end of the block. The reactive forces generated by the presser plates 38, 39 of the pistons pressing against the board are transmitted through the clamping members 32, 33 and hence to the block. The clamping members are then repositioned to enable the pistons to act against the board nailed to the lower end of the block. 
     It is envisaged that the apparatus may primarily be used for effecting an initial separation between elements of a joint whereby the joint may be subsequently fully disassembled by shearing or cutting the nails which remain in situ between the elements of the joint. The exposed nails are simply cut using a powered saw which can locate on the fulcrum plates 44, 45 for ease of cutting. 
     In an unillustrated embodiment, both arms 16, 17 are mounted for pivotal movement so that the gripping surfaces 34, 35 of the clamping members 32, 33 are generally aligned parallel to the element surfaces to be gripped and to one another. In another unillustrated embodiment the arm 16 is removed in a generally vertical altitude towards and away from the arm 17 to achieve the same objective. 
     The features disclosed in the foregoing description or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.