EP2600991B1

EP2600991B1 - Method and apparatus for correcting twist stresses in metal rods

Info

Publication number: EP2600991B1
Application number: EP11741559.6A
Authority: EP
Inventors: Simone Rupoli
Original assignee: Schnell SpA
Current assignee: Schnell SpA
Priority date: 2010-08-04
Filing date: 2011-08-03
Publication date: 2015-03-11
Anticipated expiration: 2031-08-03
Also published as: IT1401411B1; ITBO20100506A1; WO2012016998A1; EP2600991A1

Description

Technical Field

The present invention regards a method and an apparatus for correcting the effect of twist stresses in metal rods and the like, designed in particular for making reinforcements for reinforced concrete.

Background Art

It has been known that metal rods in coil, used in particular for making reinforcements for reinforced concrete, are generally fed by respective reels to be worked in machines provided with suitable straightening apparatuses. Such straightening apparatuses are usually provided with a series of operating members suitable to act on the metal rod being advanced before it reaches the successive working stations, for example the cut station and successively sometimes the folding station. Practically, such straightening apparatuses are suitable to eliminate the residual curvature caused by the winding of the rod as a coil. To such an end, the straightening members subject the rod to suitable flexure actions of intensity such as to overcome the elastic limit of the material, so as to substantially eliminate the residual curvature which, due to the elasticity, would tend to go back to the original conformation, and thus to make the straightening effect permanent.
Nowadays different typologies of apparatuses for straightening metal rods have been known. According to a widely known typology, illustrated for example in patents EP 0459869 and EP 0947256 , such apparatuses comprise one or more straightening units consisting of a plurality of couples of grooved wheels, opposite with respect to the axis of the rod and counter-rotating, to engage the same rod fed in advancement therebetween. The counter-rotating straightening wheels are arranged in sequence and with parallel axis. For example such apparatuses can provide a first straightening unit and a second straightening unit, suitable to correct prevalently corresponding components of the curvature of the metal rod on different planes, for example on a horizontal plane and on a vertical plane.
A problem which occurs in the considered field is that of eliminating or suitably reducing the effects of the residual twist stresses that can occur in the metal rods after the passage in the straightening apparatuses or are induced by effect of the unwinding from the reel from which they come. In fact such residual stresses can produce undesired effects in the rod folding step, for example producing stirrups in which the head and tail folds are not coplanar, or stirrups which ends are not close to each other, or substantially overlapped, but result open so that the whole piece does not lie substantially on a single plane, and thus comes to be very similar to a coil.
International patent application WO 01/60540 illustrates a method for reducing the undesired effects consequent to the twist stresses in metal rods which consists of making the rod pass between two rows of straightening wheels provided with a groove suitably shaped and preferably V shaped, one of which can be shifted on its own axis in a direction transverse to the feed axis of the rod, for a tract previously determined in an empirical way, so as to determine a curvilinear path of the same rod.
Nevertheless such solution cannot be applied conveniently in machines suitable to work more metal rods at the same time, such as for example the so-called bifilar machines that work two rods placed beside. In fact the straightening units commonly used in such machines are provided with straightening wheels having a double groove wherein two rods, which advance side by side, are engaged. The transverse shifting of one of the straightening wheels would obviously trigger an action on both rods and not only on the one to be corrected.

Disclosure

The task of the present invention is that of solving the aforementioned problems, devising a method that allows to perform in an efficient way the correction of the twist stresses in metal rods.
Within such task, it is a further scope of the present invention that of providing an apparatus which enables to perform the correction of the twist stresses of one or more metal rods singularly on each one of them simultaneously to the action of the straightening unit.
Another object of the present invention is that of providing a straightening unit provided with the aforesaid correction apparatus.
A further scope of the invention is that of providing a correction apparatus of simple building and functional conception, provided with securely reliable functioning and versatile use, as well as relatively economic cost.
The above mentioned scopes are attained, according to the present invention, by the method for correcting the twist stresses in metal rods according to claim 1.
According to the present invention, the method for correcting the twist stresses in metal rods provides for feeding a first rod through at least one first correction wheel provided with a grooved portion, suitably shaped, suitable to engage also transversally said first rod and with an adjacent flat bottom portion suitable to engage a second rod fed by the side of the first rod. The axial shifting of said first correction wheel is then performed, in a direction transverse to the feed axis of the rods, so as to act on said first rod without having influence on the second rod placed beside to the rod to be corrected.
Suitably, according to the invention, it is provided to feed said second rod through at least one second correction wheel provided with a grooved portion, suitably shaped, suitable to engage said second rod and with an adjacent flat bottom portion suitable to engage said first rod.
Axial shifting of said first and/or second straightening wheel is then performed, in a direction transverse to the feed axis of the rods, to perform respectively the correction of the twist effect of said first and/or of said second rod, without having influence on the rod placed beside to the rod to be corrected.
The present invention also concerns an apparatus for correcting the twist stresses in metal rods. The apparatus comprises at least one first correction wheel, rotatable according to an axis transverse to the feed axis of the rods, having a grooved portion, suitably shaped, suitable to engage also transversely a first rod, and an adjacent flat bottom portion suitable to engage a second rod fed by the side of the first rod, said first correction wheel being suitable to be actuated in axial shifting, in a direction transverse to the feed axis of the rods, to perform the correction of the twist effect of said first rod.
Suitably the apparatus comprises a second straightening wheel rotatable about an axis parallel to the axis of said first correction wheel, having a grooved portion, suitably shaped, suitable to engage said second rod and an adjacent flat bottom portion suitable to engage said first rod, said correction wheels being suitable to be actuated in axial shifting, independently from each other, in a direction transverse to the feed axis of the rods, to perform respectively the correction of the effect of the twist stresses of said first rod and/or of said second rod.

Description of Drawings

Details of the invention shall be more apparent from the detailed description of a preferred embodiment of the apparatus for correcting the twist stresses in metal rods according to the invention, illustrated for indicative purposes in the attached drawings, wherein:

figure 1 shows a perspective view of a straightening unit provided with the apparatus in hand for correcting the twist stresses;
figure 2 shows a front view of said apparatus for correcting the twist stresses;
figure 3 shows a transverse section view of the apparatus in hand, in a different operating step.

Best Mode

With particular reference to such figures, a straightening unit provided with the apparatus 10 for correcting the twist stresses in metal rods 2, object of the invention, is indicated in its entirety with 1.
The straightening unit 1 comprises, in a known way, a plurality of straightening wheels 3, 4, suitably grooved, arranged in sequence with axis parallel at opposite sides with respect to the feed axis of the rods 2. The straightening wheels 3 arranged at one side of the rods are counter-rotating with respect to the straightening wheels arranged at the opposed side, under control of suitable motor member or drawn by the rod pulled or pushed which crosses them.
In particular the straightening wheels 3, 4 are arranged staggered with respect to each other according to the feed axis of the rods 2 and have each a couple of throats 3a, 4a placed beside, with V-shaped profile, so as to engage a couple of rods 2 placed beside, fed simultaneously between the same straightening wheels 3, 4.
In the illustrated case, the straightening wheels 3, 4 are arranged on a vertical plane, with the upper wheels 3 set carried rotatable by a frame 5 that is mobile with respect to a base structure 6 whereon the lower wheels 4 are carried rotatable, under control of suitable motor members. The upper wheels 3 are staggered with respect to the lower wheels 4. Practically the upper straightener wheels 3 can be suitably approached or spaced with respect to the lower straightener wheels 4 to set the strength of the straightening on the basis of the exigencies of the row material being worked.
The correction apparatus 10 comprises a couple of correction wheels 11, 12 arranged in between in the sequence of the straightening wheels 3, 4, arranged for example staggered with respect to each other and at opposite sides with respect to the feed axis of the rods 2. The correction wheels 11, 12 have respectively their axis parallel to the axis of the straightening wheels 3, 4, transverse to the feed axis of the rods 2.
The correction wheels 11, 12 have respectively a grooved portion 11 a, 12a, defined by an annular throat substantially similar to the annular throats of the straightening wheels 3, 4, and an adjacent flat bottom portion 11 b, 12b. The grooved portion 11 a, 12a has preferably a V profile, with the sides suitably inclined to engage the rod 2 at opposite sides, or anyway it is suitably profiled to engage the rod 2 when the wheel 11, 12 is shifted along its own axis, transversely with respect to the same rod. The flat bottom portion 11 b, 12b has width suitably bigger than the diameter of the rods 2 to be treated.
More specifically, a first correction wheel 11 has an annular portion 11 a which is suitable to engage a first rod 2 fed to the straightening unit and which results more external to the straightening unit, while a second correction wheel 12 has an annular portion 12a which is suitable to engage a second rod 2 fed by the side of the first rod 2 and that results more internal to the straightening unit.
The correction wheels 11, 12 are suitable to be shifted according to their own axis, independently from each other, between an inactive position, wherein the respective grooved portion 11 a, 12a is arranged on the same longitudinal plane as the straightening wheels 2, 3 and an active position wherein such a grooved portion 11 a, 12a acts on a relative rod 2 shifting axially to its own rotation axis.
To such an end, the correction wheels 11, 12 are carried rotatable, through suitable rolling members, on a respective hub 13, 14 which is supported axially slidable by the structure of the straightening unit 1 and is associated with suitable measure members 14, 15. The measure members 14, 15 are constituted for example by respective linear potentiometers. The shifting of the correction wheels 11, 12 into the active position can be realized through suitable actuator members or also by hand, through screw members and the like.
The method for correcting twist stresses in metal rods turns out to be easy to understand from the preceding description.
The metal rods 2 to be straightened are fed in couple, by the side of each other, between the straightening wheels 3, 4 of the straightening unit 1. The rods 2 engage the corresponding throats 3a, 4a of the straightening wheels 3, 4 so as to subject the rods 2 to suitable flexure actions which enable to substantially cancel the residual curvature and make the straightening effect permanent. The rods 2 engage also the grooved portion 11 a, 12a and the flat bottom portion 11 b, 12b of the correction wheels 11, 12 which, in the inactive position, result arranged on the same longitudinal plane as the corresponding throats 3a, 4a of the straightening wheels 3, 4 (fig. 2).
If performing the correction of the twist stresses of one rod 2 or the other becomes necessary, the shifting in the active position of the correction wheel 11, 12 that engages by means of the relative grooved portion 11 a, 12a the rod 2 to be corrected is operated (fig. 3). Following such a shifting, the grooved portion 11 a, 12a of the correction wheel 11, 12 acts on the rod 2 which crosses it, realizing the desired correction action.
It is to be observed that during such correction steps, the rod 2 placed beside engage the flat bottom portion 11 b, 12b of the same correction wheel 11, 12. Therefore, the shifting in the active position of the correction wheel 11, 12, which engages by means of the grooved portion 11 a, 12a the rod to be corrected, does not have effect on the rod 2 placed beside. Practically, the correction wheels 11, 12 allow the correction of rods 2 fed to the straightening unit, independently to each other, without having influence on the rod 2 placed beside. Obviously the actuation of both correction wheels 11, 12 allows the correction, also in a differentiated manner, of both the first and the second rods 2.
The method and the apparatus in hand reach the scope of performing in an efficient way the correction of the twist stresses in metal rods fed to a straightening unit.
In particular, the apparatus allows to perform in an independent manner the correction of the twist stresses of one or more metal rods fed simultaneously to the straightening unit.
Such a result is obtained essentially thanks to the inventive idea of using correction wheels provided with a grooved portion 11 a, 12a suitable to act on a relative rod 2 and a flat bottom portion 11 b, 12b which allows to perform the shifting of the correction wheels in the active position without having influence on the rod 2 placed beside the rod to be corrected.
The apparatus described for illustrative purpose is susceptible of various modifications and variants according to the exigencies. In particular it is possible to provide that the shifting of the correction wheels from the inactive position to the active position is realized through a tilting movement of the same correction wheels, on a plane transverse to the feed axis of the rods.
In practice, the embodiment of the invention, the materials used, as well as the shape and dimensions, may vary depending on the requirements.
Should the technical characteristics mentioned in each claim be followed by reference signs, such reference signs were included strictly with the aim of enhancing the understanding the claims and hence they shall not be deemed restrictive in any manner whatsoever on the scope of each element identified for exemplifying purposes by such reference signs.

Claims

Method for correcting the effect of twist stresses in metal rods, comprising the steps of
a. feeding a couple of metal rods (2) placed side by side to a straightening unit (1) along a feed axis;

b. feeding a first rod (2) of said couple of metal rods through at least one first correcting wheel (11) provided with a grooved portion (11a), suitably shaped, suitable to engage also transversely said first rod (2), and with an adjacent flat bottom portion (11b) suitable to engage a second rod (2) fed by the side of said first rod (2);

c. performing the axial shifting of said first correction wheel (11), in a direction transverse to the feed axis of said rods (2), in order to perform the correction of the twist effect of said first rod (2).
Method according to claim 1, characterized in that it provides the further steps of
c1. feeding said second rod (2) of said couple of metal rods through at least one second correction wheel (12) provided with a grooved portion (12a), suitably shaped, suitable to engage also transversely said second rod (2) and with an adjacent flat bottom portion (12b) suitable to engage said first rod (2);

d1. performing the axial shifting of said second correction wheel (12), in a direction transverse to the feed axis of said rods (2), in order to perform the correction of the twist effect of said second rod (2).
Apparatus for correcting the twist stresses in metal rods, characterized in that it comprises at least one first correction wheel (11), rotatable according to an axis transverse to the feed axis of said rods (2), having a grooved portion (11 a), suitably shaped, suitable to engage also transversely said first rod (2), and with an adjacent flat bottom portion (11 b) suitable to engage a second rod (2) fed by the side of said first rod (2), said first correction wheel (11) being suitable to be actuated in axial shifting, in a direction transverse to the feed axis of said rods (2), in order to perform the correction of the twist effect of said first rod (2).
Apparatus according to claim 3, characterized in that it comprises a second correction wheel (12), rotatable according to an axis parallel to the axis of said first correction wheel (11), having a grooved portion (12a), suitably shaped, suitable to engage said second rod (2), and an adjacent flat bottom portion (12b) suitable to engage said first rod (2), said correction wheels (11, 12) being suitable to be actuated in axial shifting, independently from each other, in a direction transverse to the feed axis of said rods (2), in order to perform respectively the correction of said first rod and/or of said second rod (2).
Apparatus according to claim 3 or 4, characterized in that said flat bottom portion (11b, 12b) has width suitably larger than the diameter of said rods (2).
Unit for straightening metal rods, of the type comprising couples of counter-rotating straightening wheels (3, 4), arranged in sequence with axis parallel to one another and transverse to the feed axis of the rods (2) to be straightened, in opposite direction with respect to the feed axis of said rods (2), and having a couple of grooves (3a, 4a) placed side by side, with V-shaped profile, so as to engage a couple of rods (2) placed side by side, simultaneously fed between the said straightening wheels (3, 4), characterized in that it comprises an apparatus (1) for correcting the effect of the twist stresses in said rods (2) comprising at least one first correction wheel (11), rotatable according to an axis transverse to the feed axis of rods (2), having a grooved portion (11a), suitably shaped, suitable to engage also transversely said first rod (2), and an adjacent flat bottom portion (11 b) suitable to engage a second rod (2) fed by the side of said first rod (2), said correction wheel (11) being suitable to be actuated in axial shifting, in a direction transverse to the feed axis of said rods (2), in order to perform the correction of said first rod (2).
Unit according to claim 6, characterized in that said apparatus (1) comprises a second correction wheel (12), rotatable according to an axis parallel to the axis of said first correction wheel (11), having a grooved portion (12a), suitably shaped, suitable to engage said second rod (2) and an adjacent flat bottom portion (12b) suitable to engage said first rod (2), said correction wheels (11, 12) being suitable to be actuated in axial shifting, independently from each other, in a direction transverse to the feed axis of said rods (2), in order to perform respectively the correction of said first rod and/or of said second rod (2).
Unit according to claim 7, characterized in that said correction wheels (11, 12) are suitable to be shifted according to their own axis, independently from each other, between an inactive position, wherein said respective grooved portion (11a, 12a) is arranged on the same longitudinal plane as said straightening wheels (3, 4), and an active position wherein said grooved portion (11 a, 12a) acts on a relative rod (2) moving axially to its own rotation axis.