Patent Publication Number: US-7909067-B2

Title: Method, an apparatus and a means for making a reinforcement mesh

Description:
THE PRIOR ART 
     The invention relates to a method, an apparatus and a means for making a reinforcement mesh, in particular for use in concrete structures, said mesh comprising reinforcement bars which are held together by means of a flexible holding means so as to form a mesh comprising held bars at a desired mutual distance, said holding means being formed by two wires which extend respectively above and below each individual reinforcement bar, and which, when being twisted, are clamped around the individual bars. 
     Reinforcement work constitutes a considerable factor in connection with reinforced concrete work. 
     In an attempt at reducing the costs in connection with reinforcement work it is known to make reinforcement meshes which may partly be roiled up to facilitate storage and transport and may partly be mounted in a relatively simple manner. 
     This mesh may be made by means of mounted holding means for the individual bars so that these may be attached relatively easily to the holding means at the desired point, or in that the individual bars are secured to a carrying band. 
     Then, the assembled reinforcement may be arranged at the desired point. 
     However, all previous attempts at simplifying the reinforcement work suffer from various drawbacks. 
     Where joining is concerned, this takes place by welding which involves damage to the surface of the bars. This is a drawback when the bars are surface treated with corrosion protection, which is destroyed thereby, and, in addition, the bars are weakened at the points concerned. 
     Where bands are used as a holding means, these must normally be tack welded, which is both cumbersome and time-consuming. 
     Japanese published application No. 2001 182220 discloses a reinforcement mesh consisting of reinforcement bars which are held together by means of twisted wires. 
     This known structure describes a mesh which is held together by twisted wires, which wires, however, are wound around “loose” reinforcement bars and thereby provide no certainty of the tolerance, constancy of size and strength of the finished reinforcement mesh. 
     THE OBJECT OF THE INVENTION 
     It is the object of the invention to remedy these defects and drawbacks, and this is achieved by a method and an apparatus, wherein the wires are roiled up on their respective coils which are mounted diametrically opposite each other on a rotatable shaft and have a wire guide, secured to the shaft, with a wire guide element at each coil for the formation of a twist of the wires by rotation of the shaft, said twist comprising a twisting around each reinforcement bar which is kept in the position. 
     This method ensures a gentle supply, friction and guidance of the wires so that the individual reinforcement bars may be inserted between the wires before they are twisted, and also a precise positioning of the individual bars to ensure their quite precise position in the mesh. 
     Through the use of generally known control technology, this insertion and attachment of the bars and the subsequent supply of wires and their twisting are controlled such that meshes may be produced in a rapid, simple and stable manner according to the method. 
     When the desired length of the twist has been achieved, a new reinforcement bar may be inserted and held between the separated wires, and the process is repeated until the desired mesh length has been achieved. 
     When the wires are allowed to extend at an oblique angle toward the twisting point, it is possible to feed the wires in a very gentle manner, whereby optional surface treatment remains intact during the feeding and the twisting. This ensures that the corrosion protection of the mesh is optimum. 
     When the mesh is moved away from the twisting point in step with the increase in the length of the twist, it is possible currently to wound the mesh to form a mesh roll. 
     Finally, it is expedient to use coated wire and coated reinforcement bars, since this ensures the best possible corrosion protection of the reinforcement mesh before and after the embedment. 
    
    
     
       THE DRAWING 
       An example of an apparatus for performing the method will be described more fully below with reference to the drawing, in which 
         FIG. 1  shows a section of a finished reinforcement mesh, 
         FIG. 2  shows a section of an apparatus for making a reinforcement mesh. 
     
    
    
     DESCRIPTION OF AN EXEMPLARY EMBODIMENT 
     The object of the invention is to make a reinforcement mesh, and as an example of this, the example shown in  FIG. 1  will be described. 
     The reinforcement bars  3  are held at a predetermined mutual distance. 
     As will appear from  FIG. 1 , the binding  8  is composed of two wires which, when being twisted, form) the spacer  8  between adjacent bars  3 , and by allowing the wire to extend respectively above and below the individual bars the wires are clamped around these and hold them reliably and gently. 
     When heavy steel wire is used for the wires, the holding means and the spacer  8  may constitute a factor in the dimensioning of the reinforcement, which will both simplify it and reduce its costs. 
     An example of a system for the making of a reinforcement mesh according to the invention is shown in  FIGS. 2 and 3 . 
     The system comprises two or more sets of wire coils  4 ,  5  positioned opposite each other on a rotary shaft  12 . The rotary shaft  12  is driven by a drive unit  7 , as indicated in the drawing. A wire guide  13  with a wire guide element  6  opposite each wire coil  4  and  5  is mounted at the end of the shaft  12 . 
     The wire guides  13  and the wire guide element  6  are configured such that the wires  1  and  2  are conveyed in a direction toward the twisting point, and at the same time they form an opening into which a reinforcement bar  3  may be inserted. 
     When the reinforcement bar  3  is in position, as indicated in the drawing  FIG. 2  the rotation of the shafts  12  is started, thereby initiating the twisting. The wire guide element  6  is configured such that a suitable friction is achieved for a suitably tight twisting and thereby holding of the bars  3  in the twist  8 . 
     The bar  3  is moved at the same time as the twisting further forwards by the holding means  16 , simultaneously with the next bar  3  being inserted and held, in that the wires are twisted. The motor  17  moves the holding means  16 . 
     The procedure is continued in that the mesh slides down over ramps  9 , while a rolling-up drum  10  rolls up the mesh as the twist is wound off to form the reinforcement mesh, which comprises bars  3  with the predetermined mutual distance and length. 
     Meshes of any desired dimension may be made by means of this system to perform the individual reinforcement tasks. 
     As the mesh is rolled up in the making, it is easy to transport and place in position in the reinforcement. 
     Surface-treated bars  3  and wires  1  and  2 , which are not damaged in the making, may advantageously be used, thereby ensuring the optimum durability and strength.