"MACHINE AND METHOD FOR THE PRODUCTION OF METAL FIBER"

FIELD OF THE INVENTION

The present invention concerns a machine and the relative method, for the production of metal fiber to be used as a reinforcement element in concrete casts for making reinforced concrete works, in particular flooring or coverings.

BACKGROUND OF THE INVENTION

It is known to use metal fiber as a reinforcement element in structures made of reinforced concrete, such as flooring, covering, slabs, concrete beds or suchlike. The metal fiber consists of small shaped pieces of metal wire, usually with a hooked shape at the ends, for example from 20 mm to 70 mm long and with a diameter of about 0.6 mm to 1.0 mm, which are mixed with the concrete and replace the metal mesh normally used.

The pieces of metal wire normally have the form of a broken line, so as to guarantee a better adherence with the concrete and therefore confer greater resistance and rigidity, in particular with reference to the compression of the structure to be made.

The metal fiber is normally produced by machines comprising a drawing and shaping unit and a shearing unit. The drawing and shaping unit consists of one or more pairs of counter-rotating and opposite tracks on which shaping tools are mounted, with reciprocally facing tops, which draw and simultaneously shape a plurality of metal wires disposed one adjacent to the other.

The shearing unit is located downstream of the drawing and shaping unit and performs the shearing to size simultaneously on all the wires being worked.

This type of known machine, however, entails slippage and a differentiated advance of the wires being worked, with a consequent misalignment of the shearing, which is carried out at points that are too far forward or too far back with respect to what is required, so that the pieces are unusable with a consequent high production of rejects.

A machine is also known in which the counter-rotating tracks have, or support, specific shaping elements which impart the shape to the wires at least in the terminal part of their advance toward the shearing unit.

In this latter type of known machine, the tracks are reciprocally disposed so as to have relative convergent shaping segments, or alternatively, parallel.

Although this type of machine guarantees great shaping precision of the metal wires, it has a limited flexibility due to the specific nature of its use, especially with regard to the reciprocal positioning of the tracks, which must be positioned and reciprocally equipped on each occasion according to the specific sizes and shapes of the wires to be shaped.

Furthermore, the tracks in this type of known machine slide, at least with their forming segment, on fixed guides or with respect to pinions, according to the requirements of the final product, which have an abutment function for the components of the track.

This solution on the one hand entails a considerable overheating of the individual components of the track and on the other hand does not guarantee a sufficient and uniform rigidity of the track along the forming segment of the fibers. Consequently, the geometric characteristics of the fibers are not repeatable and it is difficult to correct the compression parameters.

Furthermore, the working speed of this type of known machine is limited due to the lack of lubrication than can be made on the tracks, in order to guarantee that no part of the lubricant used is deposited on the finished product. One purpose of the present invention is to achieve a machine and the relative production method, which allow to produce metal fiber having substantially any shape whatsoever, in particular shapes with rectilinear segments of a certain entity, without causing slippage and misalignment of the metal wires being worked and hence guaranteeing that a final product of high quality and precision is obtained.

Another purpose of the present invention is to make a machine for the production of metal fiber which is simple, reliable and versatile and which allows to modify the shape to be made with quick and easy equipping operations.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION The present invention is set forth and characterized in the independent claims,

while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

The machine according to the invention comprises, like traditional machines for the production of metal fiber, a drawing and shaping unit, able to feed and simultaneously shape a plurality of metal wires, and a shearing unit, located downstream of the drawing and shaping unit, able to shear to size said metal wires.

In accordance with the above purposes, the drawing and shaping unit comprises at least first and second counter-rotating track means, which have or support shaping means able to impart the shape to the metal wires and then to remain gripping them with relative forming segments at least for a part of their advance toward the shearing unit.

The first track means comprises at least a first forming segment facing and opposite an analogous second forming segment of the second track means. According to a characteristic feature of the present invention, the drawing unit comprises contrast means of the adjustable type, which is operationally associated with at least one of either the first forming segment and the second forming segment, so as to allow a variation in the distance and/or reciprocal inclination of the first forming segment and the second forming segment. With the present invention, it is therefore possible to selectively vary, and possibly in a differentiated manner along the length, the contrasting action applied on the relative forming segment, and to specifically adjust the degree of tension of the forming segment, according to the type of shaping and/or shaping means provided. In this way, apart from preventing slippage and misalignment of the metal wires being worked, the machine according to the present invention allows to make uniform in a controlled manner the tension of the track means at least in their forming segment, allowing to repeat the geometric characteristics of the metal fibers produced. Furthermore, the possibility of selectively varying the distance and/or the reciprocal inclination of the two forming segments determines a considerable increase in the flexibility of the machine, with the possibility of modifying the shape to be made, or the sizes of the wire to be shaped, with simplified, quick and

- A -

easy equipping operations.

According to a variant, the contrast means comprises at least a plane contrast element disposed in contact with the relative forming segment of the track means, and an adjustment mechanism operationally connected to the plane element and disposed on the side opposite the forming segment with respect to the plane element.

According to a variant, the adjustment mechanism comprises one or more eccentric shafts, or cam shafts, disposed transverse to the plane contrast element and able, according to their angular position, to determine the positioning of the relative contrast element. In this way, a coordinated distancing or approach is consequently achieved of the corresponding forming segment with respect to the other forming segment.

In a first solution, the track means are reciprocally convergent toward the terminal part of the advance of the wires. In this case, the first segment of the track means only determines the advance of the metal wires, whereas the second segment, facing toward the shearing means, determines the progressive shaping thereof until the final form of the metal fiber is achieved.

Alternatively, the track means are substantially parallel to each other.

According to another variant, each of the track means comprises a chain disposed and moved annularly around respective drawing wheels and tensioning devices.

According to a variant, each chain is disposed between a drawing wheel and a tensioning guide. The tensioning guide is selectively movable toward/away from the drawing wheel so as to selectively tension/loosen the chain. Advantageously, the tensioning guide is selectively movable by means of a linear thrust actuator.

According to another variant, each chain is disposed between two drawing wheels and a third wheel that functions as a tenser.

According to another variant, each chain consists of a plurality of links, each of which is conformed so as to directly support a relative shaping mean and comprises at least two lateral rotary members by means of which it slides at least with respect to the contrast means.

In this way it is possible to reduce the working temperatures, preventing overheating of the components of the chain, which improves the precision and

uniformity of the metal fiber.

Furthermore, the shearing unit is driven in coordination with the advance of the metal wires, so as to cut them always at the same point, so that the shaped pieces obtained are always exactly the same. BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a side view of the machine for the production of metal fiber according to the invention;

- fig. 2 shows a section from A to A of the machine in fig. 1, in a first operating condition;

- fig. 3 shows a section from A to A of the machine in fig. 1, in a second operating condition; - fig. 4 shows an enlarged detail of fig. 1 ;

- figs. 5a-5g show some examples of metal fiber that can be made with the machine and method according to the present invention.

DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF

EMBODIMENT With reference to the attached drawings, the number 10 denotes in its entirety a machine for the production of metal fiber 11 according to the invention.

The metal fiber 11 consists of small pieces 12 of metal wire 18, each of which has a rectilinear segment 12a and one or more anchoring bends 12b (figs. 5a-5g). These conformations, which can also be of a known type, can be chosen on each occasion according to the type of work to be done, the type of concrete or other, and function as bonding elements so as to guarantee an optimum resistance to compression.

The machine 10 (figs. 1 and 2) comprises a frame 13 on which are mounted a drawing and shaping unit 14, able to act simultaneously on a plurality of metal wires 18, advantageously as many as twenty five and more, and also a shearing unit 15 able to shear to size the metal wires 18 to obtain the pieces 12.

The functioning of the drawing and shaping unit 14 and the shearing unit 15 is coordinated by a command and control unit, for example a PLC, provided with a

command panel, of a substantially known type and not shown here.

The drawing and shaping unit 14 comprises a pair of tracks 20, comprising an upper track 21 and a lower track 22, having respective forming segments 21 a and 22a, facing and opposite each other. Upstream of each pair of tracks 20 there is also a guide profile 19, through which a plurality of metal wires 18, fed from respective coils, which are preferably kept substantially fixed, are conveyed. Advantageously, the metal wires 18 are kept parallel to each other and aligned, toward said pair of tracks 20, on a horizontal plane "X" disposed in an intermediate position between the forming segment 21a of the upper track 21 and the forming segment 22a of the lower track 22.

The guide profile 19, in a known manner, has a plurality of guide channels (not shown), one for each metal wire 18.

Each track 21, 22 consists of a driven toothed wheel 23 and a tensioning guide 24, arch-shaped.

Each track 21, 22 is mounted in a closed ring between the toothed wheel 23 and the tensioning guide 24, and consists of a plurality of links 25. Each link 25 comprises laterally two sliding wheels 28 (fig. 4), which are able on the one hand to engage on the toothed wheel 23 and on the other hand to slide at least with respect to the tensioning guide 24.

On the links 25 relative blocks 27a, 27b are mounted, described hereafter in greater detail.

The tensioning guide 24 is able to be selectively moved closer to/away from the toothed wheel 23 by means of a linear actuator 26, in order to adjust in the desired manner the tension of the relative track 21, 22.

The lower tracks 22 are made to rotate, with an advance toward the shearing unit 15, by a drive member, of a known type, associated with the relative toothed wheel 23; the upper tracks 21 instead are made to rotate, in the opposite direction with respect to the lower tracks 22, so as to also advance in the direction of the shearing unit 15, by the relative toothed wheel 23 which takes its motion, advantageously, from the lower tracks 22 themselves.

The drawing and shaping unit 14 also comprises two contrast members 35, each disposed in cooperation with a relative forming segment 21a or 22a.

In particular, each contrast member 35 comprises a contrast plate 36 disposed to the rear of the blocks 27a and 27b, in contact with the links 25 of the relative track 21, 22, in correspondence with the forming segment 21a, 22a.

Each contrast member 35 also comprises two cam shafts 37 disposed transverse and in contact with the contrast plate 36, with respect to a surface of the plate 36 itself, opposite the surface with which it contacts the links 25.

Each cam shaft 37 is mounted rotary on the frame 13 and in this case comprises two eccentric sectors 39 angularly coordinated with each other and able to contact directly the contrast plate 36. In this way, according to the angular position of the eccentric sectors 39, the contrast plate 36 is thrust, or kept, against the links 25 of the relative forming segment 21a, 22a, with different tensions.

In this way an increase or decrease is determined of the reciprocal distance between the two forming segments 21a, 22a, or different degrees of inclination are defined between said two forming segments 21a, 22a.

Each cam shaft 37 can be selectively associated with relative movement mechanisms 40, able to actuate a controlled movement thereof so as to define desired degrees of displacement and adjustment of the position of the contrast plates 36. In the solution shown in the attached drawings, the upper tracks 21 and the lower tracks 22 are disposed reciprocally converging with respect to the plane X, toward the terminal part of the advance of the metal wires 18, that is, toward the shearing unit 15, so that the latter are shaped mainly in proximity to the shearing unit 15. An analogous solution is described and claimed in the European patent EP-B-1695775.

With the solution according to the present invention, acting individually on the cam shafts 37 of the contrast members 35, at least the two forming segments 21a and 22a can be selectively distanced, moved closer or reciprocally inclined in a different way, according to the type of shaping to be done. In particular, at inlet of the tracks 21 and 22 on the side of the guide profile 19, the blocks 27a and 27b are not substantially gripping the metal wires 18, until maximum shaping pressure is exerted in correspondence with the terminal segment, facing toward the shearing unit 15, of the advance of the wires 18

between the tracks 21 and 22.

On their external surface the blocks 27a and 27b have a part, in this case at their front end, conformed so as to define the bend of the ends 12b of the pieces 12 of the metal fiber 1 1 to be produced. In particular, on each link 25 of the upper track 21 a first block 27a is mounted whose front end part has a ridge 30, substantially rectangular in section, having a profile with shape and sizes coordinated with the development of two contiguous and specular segments that will form, after shearing, the end 12b of two distinct pieces 12. Each link 25 of the lower track 22 is instead associated with a second block 27b whose front end part has a hollow 33 with a conformation complementary to that of the ridge 29 of the first block 27a. In particular, the hollow 28 is slightly larger than the ridge 29, so that the deformation of the metal wires 18 occurs with the ridge 29 progressively entering into the hollow 28, thus generating the trapezoid shape of the metal wires 18.

With reference to figs. 5a to 5g, according to the specific shape of the metal wires 18 to be obtained, the two blocks 27a and 27b are selectively replaced by others that have respective and specific ridges and hollows.

Always according to the shape of the metal wires 18 to be obtained, the distance and reciprocal inclination of at least the two forming segments 21a and 22a of the two tracks 21 and 22 are selectively varied by the action of the specific contrast member 35.

It is clear however that modifications and/or additions of parts or steps may be made to the machine 10 and the method as described heretofore, without departing from the field and scope of the present invention.

For example, it comes within the field of the present invention to provide that the machine 10 comprises a protection and covering structure, not shown, able to normally prevent access to the various mechanical members of the machine 10 during functioning. Advantageously, the protective structure is provided with at least a portion that can be selectively opened so as to facilitate the equipping and maintenance operations of the mechanical members.

It is also clear that, although the present invention has been described with

reference to specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of machine and method for the production of metal fiber, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.