EP2433724B1

EP2433724B1 - Feeding system and relevant transversal feeder for entire bars or steel bars suitable for automatic plants producing electric welding wire netting with particular shapes

Info

Publication number: EP2433724B1
Application number: EP20110177842
Authority: EP
Inventors: Claudio Bernadinis
Original assignee: AWM SpA
Current assignee: AWM SpA
Priority date: 2010-09-27
Filing date: 2011-08-17
Publication date: 2014-03-05
Anticipated expiration: 2031-08-17
Also published as: IT1402246B1; ES2468816T3; ITUD20100173A1; EP2433724A1

Description

FIELD OF APPLICATION

The present invention relates to a feeding method and the relative transversal feeder of whole bars or straight steel rods for plants for the automatic production of planar electric welding wire netting with particular shapes. The shaped wire grids are generally used in the building industry for the production of walls, beams and modular elements.
The invention simplifies first of all the handling of the feeding bars in the transversal direction of the electric welding wire netting, with consequent advantages from the point of view of shorter construction times, thus increasing the production level.
The method is based mainly in the fact that, instead of using single bar segments to form the special grids in the transversal direction, the method uses long, whole, rectilinear bars from which are obtained any bars having the desired length or cropped bar segments at the moment of their geometrical positioning on the plane on which the net is being formed.
Said rectilinear bars are whole, having a length that is the sum of the single cropped pieces to be obtained subsequently, before they are positioned, as they are automatically cut to length and then positioned on the work plane an instant before being electrically welded on the previously arranged longitudinal bars.
In this manner, the invention reduces the handling of long or short cropped pieces, reducing at the same time the number of cycles for their transversal positioning, and increasing the productivity of the whole plant.

PRIOR ART

In the present state of the art, in the field of automatic plants for the production of electro-welded planar grids of special type, with perimetric shapes and/or internal voids suitable for the construction of special reinforcing wire grids used in the construction of prefabricated elements in the industrialized building field, shaped grids are well known as formed on a horizontal plane by positioning the various steel bars or rods of different lengths, distinct cropped pieces before being electro-welded, both in a lengthwise and in a crosswise direction.
To form said nets, it is necessary to have parallel wire rods, positioned longitudinally and transversally, at right angles to and overlying each other, which are subsequently automatically electro-welded at their points of intersection. For longitudinal rods, various methods and the relative machines are known in the field, including also some patents from the same Company filing this application; see for example Patent PCT/IB2010/052773.
In the state of the art, various systems are known for positioning the wire rods in a direction transversal to the direction of production of electric welding wire nettings. One known method, for example, is to arrange beside the machine one or more coils of wire rod that is then unwound, and the wire is straightened and immediately cut, and then positioned transversally just before being automatically electro-welded on the longitudinal wires. This solution presents various drawbacks when it is necessary to position steel bars of different diameters and different lengths in a discontinuous manner; that is, it is necessary to have a particular handling of the wire rods in order to arrange them in the transfer position at the exact moment during the formation of the grid.
At present, to avoid the complexity of handling said rods or cropped pieces, particularly for grids of complex type, that is, shaped around the perimeter an/or internally, the exact succession of the rods to be inserted transversally during the formation of the net is first arranged, in another area beside the machine. The wire rods are then supplied to the transversal feeder or transfer device. This methodological solution requires the handling of the rods one at a time, in the desired design sequence, using various devices that have an effect on production costs and lengthen the process times.
EP 0 482 842 and EP 0 733 416 disclose automatic plants producing electric welded wire netting wherein bars or rods are cut at the requested lengths before being transversally loaded into the welding device.
Consequently, each cut transverse bar has to be loaded individually by a transport device generating a rotation of the bar about 90 °.
Also known is a jib-boom system for the transversal positioning of the bars, starting from a position parallel to the stream of production of the grid, and arranging on a jib boom or arm a small number of precut bars, of equal or different diameter and length, in the proper sequence of their transfer on the work plane; the jib boom will rotate 90°, to prearrange transversally the bars or cropped pieces to be inserted.
This solution, too, although it is an advanced solution to the problems of dealing with different bars, is however uneconomical, because the jib boom - although it is conceived with multiple parallel stations, each holding a single bar or cropped piece - is expected to operate continuously with plural transfer cycles in order to form a complete shaped electro-welded netting. This is time-consuming with regard to feeding and positioning the bars.
Therefore, to overcome the disadvantages encountered, the automated method and apparatus of the present invention is proposed, to guarantee a faster feeding of the transversal bars in the production of the electro-welded steel grid, thus increasing the output of the whole plant.

PURPOSE OF THE INVENTION

The purpose of the invention is therefore to achieve a new method and the relative automated machine or apparatus using various whole, rectilinear bars having an equal or different diameter and/or length to insert them transversally, at right angles to the direction of production of the planar electro-welded steel grids of special type, with perimetric shapes and/or with internal voids, having the following main characteristics:

the steel bars fed in the direction transversal to the stream of production of the special grids are positioned parallel to each other, on a long rotating arm with multiple stations. The rectilinear bars of the same or different diameter, each of them whole (that is, in one piece), have a length equal to the sum of the parts of the mesh to be formed (evidently subtracting the void parts of the shaped grid): this avoids the production of any wasted material, since the bars are cut or left uncut, as the case may be, without waste, and are immediately handled to be placed in a position parallel to the work plane in the welding unit;
the horizontal bar-holding rotating arm operates above the grid production plant, for example with a 90° rotation, and is hinged on a vertical axis on the side of the machine, near the underlying automatic welding unit, and operates from a position parallel to the work stream in which it receives the long bars to an orthogonal position, where it releases said bars and lets them fall by gravity onto the underlying parallel transfer device, which conveys the bars one after the other on the automatic shearing unit;

said arm is provided with plural single stations carrying long straight bars and provided with a plurality of automatic grippers that grip, carry and release the bars by gravity. The long bars are held suspended by the automatic grippers from above, so that when the grippers are opened the bars fall by gravity onto the underlying parallel transfer device (of screw type or other suitable device), transferring one bar at a time for the cutting to length phase and to the subsequent means of transportation for their proper positioning on the grid being formed with known automatic monitoring and control means;
once the bar is cut to length, it is handled and set in position on a single station of a multi-station storage unit, driven by various closed-link chains, each provided with special holding devices, aligned and operating in a vertical direction and parallel to each other, so as to be able to carry the individual straight bars from an upper position to a lower position;
a fast automatic bar transfer unit arranged in horizontal position, also consisting of a long closed link chain, is provided with automatic clamping grippers that collect one bar at a time from said bar storage unit and carry it to a position below the working plane, where an automatic loading and positioning device arranges it under the longitudinal bars that form the grid, in the automatic electro-welding unit.

The invention realized with the characteristics indicated above achieves the objective of reducing the arm feeding and shifting cycles as it carries long bars, that are multiples of the cropped bar pieces to use, and at the same time increases the output because the feeding of the cropped bars is continuous, is carried out one at a time, and the bars are positioned correctly for the formation of the steel grids of complex shapes.

ESSENCE OF THE INVENTION

The objectives of the invention are achieved according to the characteristics of the main claim through the design of a new method of feeding the transversal bars suitable for plants for the production of electric welding wire netting with particular geometrical shapes, and a relative apparatus for said grid production.
At present, to feed the transversal bars into the production plants for shaped electro-welded steel grids, cropped pieces or bars of different lengths defined with automatic mechanical systems are handled, while with the present invention the objective is to reduce the feeding times and to cut down the number of feeding cycles, thus increasing the output of the whole grid production plant, with considerable advantages related to the lower maintenance required and the consequent longer life of the mechanical devices involved.
The method is based first of all, in the use, for the transversal feeding in the production of planar electro-welded grids, of whole or uncut steel bars, rectilinear, of equal or different diameters, each of a length equal to the sum of the grid parts to be produced (evidently subtracting the void parts of the shaped grid). The length of said bars can also be greater than the overall width of the grids to be formed, providing it is a multiple of the cropped pieces that are then used in their positioning on the electro-welding unit with the corresponding longitudinal bars forming the grid.
The bars used in the transversal insertion usually come from coils to be unwound and straightened; they are intelligently cut to length following the principle that they must be multiples with respect to any of the cropped pieces having shorter lengths, whose sum is ideal to be handled. At first, they have a direction that is parallel to the stream of production of the electro-welded grid, that is, the same direction as the ones of longitudinal type. Said transversal bars are picked up automatically by a rotating arm, placed at a higher position, operating horizontally, provided with plural parallel stations, so that it is possible to carry a plurality of long bars at the same time. The arm picks up the bars form an longitudinal position external to the forming machine and sets them down at right angles by making a 90° rotation, placing them on suitable transfer means located above the grid forming devices.
When the arm automatically reaches the transversal position, it lets the bars it carries fall by gravity on a plurality of transfer means of parallel type, or a series of synchronized screw feeders or other equivalent means. Said screw feeders move the bars one at a time in parallel direction toward the automatic bar feeding unit, which moves the bar transversally toward the outside of the machine for a distance according to design, always at a higher level with respect to the grid formation plane. Afterwards, the bar is cut and collected by a suitable individual loader provided with multiple holding devices, integral with a closed-link chain. On the whole, the loader is generally provided with a plurality of similar chains arranged parallel to each other and operating vertically from a position above a lower one, synchronized with each other so as to enable them to carry the bar cut at any length horizontally, from a higher position to a lower one, for example at a height lower than the electro-welding plane. At this point, the single bar or the transversal piece cut to length is collected by a horizontal transfer device, formed by a long closed-link chain provided with automatic clutching grippers, that operates transversally from the lateral area for collecting the individual bars to und
erneath the electro-welding plane. This horizontal transfer device is driven automatically in an intelligent mode toward its destination, since it has the possibility of simultaneously carrying a plural number of cropped pieces spaced from each other according to grid production design, in an aligned manner, in order to position them correctly near the automatic device for loading them onto the electro-welding line.
The method of using long rectilinear bars of a lengths that is a multiple of the cropped pieces to be obtained for the transversal insertion of the same on the automatic electro-welding unit for forming the planar, shaped metal grid, and the relative above-described automatic operation devices are advantageous to obtain the decrease of the handling cycles for the handling of the cut bars to be inserted and the correct positioning of the same into the automatic electro-welding unit for forming shaped or special planar steel grids, to increase their output, while lowering the maintenance and increasing the life of the mechanical equipment.

ILLUSTRATION OF DRAWINGS

One solution according to the present invention is shown by way of preferred but not limitative example in the five enclosed drawings, wherein:

Fig. 1 illustrates, in a plan view, the area of formation of the special electro-welded steel grid, shaped and/or with voids, showing the rotation of the upper arm for the multiple movement of long rectilinear steel bars, which are carried from a longitudinal position parallel to the production line to an orthogonal one above the grid formation plane;
Fig. 2 illustrates, in a partial side view, the plant of figure 1, showing the automatic devices involved in inserting the bars or transversal cropped pieces in the automatic electro-welding unit from a position below the grid formation plane;
Fig. 3 illustrates, in a partial and enlarged front view, the zone of arrival of the long transversal bar, which is loaded individually in an intelligent mode and made to pass through an automatic shear, which cuts it to length and sets it down on the vertical conveyor, for its parallel movement from a higher level to a lower one with respect to the grid formation plane;

Fig. 4 illustrates, in a side view, the closed-link-chain vertical conveyor, formed by a plurality of single aligned units, each provided with collecting devices for the cut bars to be moved from a higher position to a lower one, so as to feed the last horizontal transfer device;
Fig. 5 illustrates in a summary front view the plant seen from a point upstream of the grid formation point, showing in particular above the electro-welding unit the 90° rotating arm holding the long bars, on the side opposite the vertical conveyor, loaded with various single parallel and horizontal bars, below the intelligent, horizontal transfer device, made up of a single closed-link chain provided with relative grippers that grip the cropped pieces to finally carry them near the electro-welding unit, feeding it from below.

As can be seen from the various figures, the method used in feeding the transversal bars for the production of shaped electro-welded steel grids (5), formed by longitudinal bars (4)(4.1)(4.2) and transversal bars (3.1), is based first of all on the use of bars (3) or rectilinear, parallel steel bars arranged longitudinally, parallel and laterally to the grid production plant. Usually, these bars or wire rods are drawn from the unwinding of a steel wire coil (2) installed on a relative decoiler (1), and by means of suitable straightening devices, known in the art, the coiled wire is straightened and cut to length. These steel bars (3) or wire rods have a predetermined length to avoid needless waste, that is, they have a multiple length that is the sum of the various lengths of the rods that will subsequently be cut to length. In this manner, the machine is fed with long bars, thus reducing the number of transportation cycles to the area where they are being used.
A horizontal rotating arm (6), hinged on a vertical axis (7), above the machine, is designed to move automatically by 90 degrees, from an external loading position parallel to the machine, from a longitudinal position to an orthogonal position, where the bars are discharged by gravity. Said arm is provided with a plurality of bar holding stations, each equipped with a plurality of automatic grippers (12) that hold the bars parallel to each other from above.
Thus, when it reaches the position orthogonal to the grid production stream, the arm releases the bars (3) onto a plurality of parallel transfer devices (13) that feed the transversal insertion unit one bar at a time. The dragging device (8) is intelligent, in the sense that it moves the bar (3) forward through an automatic shear (9) designed to cut the bar (3) to obtain a cropped piece (3.1), pushing it laterally in a transversal movement past the grid production plane.
Thus, the cropped pieces obtained from a single bar can be different. Each cropped piece is collected by a relative vertical transfer unit (14) with an aligned head, so that all the cropped pieces (3.1) are vertically aligned with respect to the head at the end toward the electro-welding unit (10) (this will be used subsequently to space the cropped pieces exactly from each other on a horizontal line).
The vertical transfer unit (14) is made up of a plurality of closed-link chains (15) arranged vertically, parallel and aligned, operating synchronously, each equipped with relative aligned holding devices (16) designed to collect the cropped pieces (3.1), so as to carry the parallel and horizontal cut bars from a higher position to a lower position, and more precisely under the horizontal electro-welded grid formation plane, where the horizontal transfer unit (17) operates.
The horizontal transfer unit consists of a closed-link chain that moves transversally to the stream of production of the grid, from the external lateral operating area of the vertical transfer unit (14) to the electro-welding unit (10). It is equipped with a plurality of automatic grippers that can grip the horizontal cropped pieces, one after the other spaced at predetermined distances from each other. In this manner, the transfer device arranges one or more transversal cropped pieces under the electro-welding unit, where automatic loading arms (11) collect said cropped pieces and arrange them aligned under the longitudinal bars on the lower electrodes of the automatic electro-welding unit (10). Here the longitudinal bars and the transversal ones are welded together to form the steel grid (5).
Naturally, the invention is not limited to the embodiments of the apparatus that carries out the method described above, based on which it is possible to foresee other forms and modes of embodiment, and the construction details may however vary without thereby departing from the substance of the invention as described and claimed hereunder.

Claims

Feeding method suitable to orthogonally feed automatic plants for the production of electric welding wire netting with particular shapes, perimetrical and/or with internal paces, characterized by the fact that it provides the transversal loading of long, entire and rectilinear bars (3), with lengths equal to the sum of more crops (3.1) suitable in the formation of special nets (5), right fitted without scraps during the insertion procedure, the long, entire and rectilinear bars (3) are arranged and put in place, with longitudinal and parallel direction as regards to the stream of production, in upper position as regards to the production surface of the net (5), some bars are collected and automatically turned 90 degrees, by means of adequate equipment, then placed on the horizontal plane from a parallel and external position as regards to the plant, to an orthogonal position over the automatic welding unit of the metallic net, the long bars (3), set in transversal position, are addressed one by one to the shearing unit (9) that cuts them to the right length, in one or more suitable crops, which are pushed outside the welding area, always in transversal direction, one by one collected by means of an adequate and vertical transfer equipment (14) and afterwards by means of an horizontal one (17), with the purpose to transfer said crops (3.1) from an upper position to a lower one, that is below the welding plane (10), so that they can return from the outside area close to the automatic welding units, then loaded below the longitudinal bars forming the special nets, and finally welded among them.
Automatic apparatus related to the feeding system described in the preceding claim, characterized by the fact that it includes:
- an upper arm (6) hinged in (7), rotating 90 degrees on an horizontal plane over the plan of formation of the net, this arm is endowed with a plurality of parallel bar-holders (3), each of them provided with a plurality of automatic pliers (12) which grab and move the bars from a higher to a lower position, so that the unblocked bars may fall cause of the force of gravity on the below placed parallel transferring equipment (13), transversally set, said arm operates from an external position, parallel as regards to the stream of production, where the long bars (3) are disposed, to an orthogonal position over the plane of production of the net (5);

- a device for parallel and singularly transfer (13) the bars, composed by a plurality of screws rotating in coordination among them, with synchronized movements on their axle, the bars, transported by the upper arm (6), fall down cause of the force of gravity, this unit, transversally set as regards to the stream of production, is able to move a long bar one by one, towards the rolls of the dragging device (8);

- an automatic dragging device (8) that pushes the bar (3) through the shearing unit (9) exactly for the length of the requested transversal crop, the bar juts out of the plant orthogonally, towards the outer side, over the plan production of the net;

- an automatic cutting unit, downstream placed as regards to the dragging device (8), that cuts the bar (3) in one or more crops (3.1), then singularly picked and supported by a special vertical transfer equipment (14);

- a vertical and automatic transfer unit (14) for crops (3.1), formed by several parallel and vertical elements, each of them consisting of closed link chain (15) and equipped with special devices supporting the crops (3.1) from the bottom, said devices are horizontally lined up on the above mentioned elements, and move downwards in synchrony so that to move the crops from an upper an external position as regards to the plant, to a position under the working surface;

- an horizontal transfer unit (17) for crops (3.1), that operates from an external position as regards to the production area of the net, to the automatic electro-welded unit, said unit is formed by a closed link chain equipped with several devices or automatic pliers which grab the crops one by one, with prearranged distances among them, moving the crops from the vertical transfer unit below the plane of the welding electrodes;

- finally, a loading unit equipped with automatic devices (11), collecting the crops (3.1) from the horizontally transfer unit (17), then arranging them below the longitudinal bars (4) (4.1) (4.2) and over the lower electrodes of the electro-welded unit (10), where the welding between the longitudinal bars and the transversal corps (3.1) takes place.