The present invention refers to a method and a mechanism for selection and feeding of one at a time, from a bundle of several wires or wire rods or tubes or other materials of prismatic cross section, which are placed on different feeding lines, where these lines may or may not be parallel to each other in space, and they may or may not lie on the same plane. The location of processing, where the feeding lines converge at, may be fixed with respect to the feeding lines or may be able to move at a direction parallel to its axis or may be able to even turn its axis at an angle with respect to the initial axis in order to facilitate the operation of the mechanism.
Selection of each wire to be fed is conducted without the employment of any special mechanisms, in a very simple way, which is explained below.
The method and the mechanism are applied to straightening machines, where several, usually parallel with each other, wires or wire rods are pulled from pay-off stations, are straightened in the respective straightening units, and consequently, one of them is selected for advancement to a cutting, storage and transfer mechanism.
The present invention is also applied to bending machines, where several wires of different cross section are fed at, and one of them is selected for straightening and feeding towards the bending mechanisms.
The present invention can also be applied to welding machines, which are used for the production of different mesh geometries, where the distance between the longitudinal wires varies.
The usual practice consists of placing the straightening units on a plate, which can move on its plane, in a direction transversal to the parallel wires, so that one straightening wire line is always placed along the cutting and storage axis of the already straightened wires or along the axis of any consecutive processing. Whenever a change of wire is required, the plate moves at the transversal direction and the selected wire is aligned to the axis of cutting or storage or of any consecutive processing step.
Alternatively, the straightening units are placed on a mechanism, which is able to rotate about an axis, so that the selected straightening unit is aligned with the axis of cutting or of any consecutive processing step.
The main disadvantage of both the above methods and applications is the complexity and the size of the mechanical construction and the significant time, which is required for the changing of wire.
The mass of the plate, which supports the straightening units is significant, hence its structure much be robust and a complex, therefore expensive, mechanism is required for the plate movement. Furthermore, in the case of wire changing, additional time is required for the plate movement, so that the selected wire line be aligned with the axis of any further processing step, and consequently, the productivity of the machine is reduced.
The purpose of the present invention is to present a method, which will resolve any 5 problems of the existing methods and machines and which will lead to the manufacturing of a mechanism, which will make possible the fast interchanging of production lines, simply and quickly.
The aim of the present invention is to supply a mechanism, which will automate the process of interchanging of the production lines, will maximize flexible operation, will minimize the time required for the changing of production lines, and as a mechanism, it will be simple in its design, user-friendly and reliable in operation.
The method of the present invention is based on the elasto-plastic behavior of metals, when they undergo bending. In FIG. 1, wire (1) advances along the axis AA′ towards the straightening unit (6), where it undergoes straightening, and then the straightened wire is guided, so that it is aligned to the axis OO′ after an interval X, where the wire is bent and is finally taking an S shape. For materials which express an elasto-plastic behavior, such as metal wires, wire rods, metal tubes and generally the materials of prismatic cross section, for a certain S shape, there exists an adequate convergence distance X where the material remains in the elastic region and it does not exhibit any permanent deformation.
More specifically, there is a relation between the geometry of the S-curve, the transversal distance Ψ, the wire diameter, the convergence length X, and the material yield point, so that no plastic deformation of the wire occurs.
According to the method of the present invention, the axis AA′ of the wire feeding can be maintained fixed with respect to the axis OO′ of the collection mechanism. In addition, the axis of feeding of the wire can move with respect to the axis OO′ of the collection mechanism or the axis OO′ of the collection mechanism can move with respect to the axis AA′ of the wire feeding. Furthermore, the two axes can change the angle of convergence between them. Prerequisite of all the above changes is that no plastic deformation of the fed material occurs.
According to the method, FIG. 2, the feeding wires (1), (2) etc. and the straightening units (6), (7) etc., are placed on parallel axes and at adequate distances between them. The common cutting location (23) and the beginning of various mechanisms, e.g. bending devices or transport mechanism towards the bending devices, are aligned with axis OO′. The distance X between the common cutting location and the locations where the wires exit from the straightening units is selected to be sufficiently long, so that none of the converging wires is plastically deformed
The minimum X distance is defined for the worst case, so that all the wires may arrive at the common convergence location, without any plastic deformation.
During operation, only one wire is fed at each time.
The straightening units may be placed on the same plane and parallel to each other, at various relative to each other locations, FIG. 3, whereas their convergence may begin at different locations, so that a variety of manufacturing goals are achieved, such as minimum distances between straightening units.
The straightening units may also be placed not on the same plane but may lie on different planes, FIG. 4. However, the wires must converge towards the convergence location without any plastic (permanent) deformation.
The wire lines may lie on the same plane but not parallel to each other, being placed at an angle with respect to the common convergence line.
In addition, the axes of the wire lines may be not lie on the same plane in space, as soon as they converge towards the common axis OO′, through the appropriate s-shaped curves.
Furthermore, the axis OO′ may move at a direction parallel to itself, FIG. 2 (y), or at an angle, FIG. 2 (φ), with respect to the lines of feeding of the wires, as soon as the fed material does not undergo any plastic deformation.