EP3147042A1

EP3147042A1 - An apparatus for deforming a metal bar up to obtaining a spiral

Info

Publication number: EP3147042A1
Application number: EP16190851.2A
Authority: EP
Inventors: Lorenzo Verzola
Original assignee: Mille Srl
Current assignee: Mille Srl
Priority date: 2015-09-28
Filing date: 2016-09-27
Publication date: 2017-03-29
Also published as: ITUB20153974A1

Abstract

An apparatus (10) for deforming a metal bar (7) up to obtaining a spiral (3), comprising: a guide housing (8) for the metal bar (7), fixed to the frame; a deforming shaft (1); a first rotating member (41) which comprises a first gripping surface (51) of the metal bar (7); a second rotating member (42) which comprises a second gripping surface (52) of the metal bar (7); a fourth abutting surface (34) which projects from the lateral surface of the deforming shaft (1); a fifth abutting surface (35) which is facing the fourth abutting surface (34); a sixth abutting surface (36) which projects from the lateral surface of the deforming shaft (1), which is orientated in an opposite direction to the fourth abutting surface (34), which is distanced from the fourth abutting surface (34) by a distance that is substantially equal to a pitch of the spiral (3) to be obtained by the deformation of the metal bar (7). The apparatus (10) is configured in such a way as to carry out a plurality of operating cycles, each comprising: the gripping of the metal bar (7), actuating the first rotating member (41) and the second rotating member (42) in a first rotation direction (G) up to reaching a second angular position (E2), disengagement of the first rotating member (41) and the second rotating member (42), actuating the first rotating member (41) and the second rotating member (42) in a second rotation direction, opposite the first, up to the first angular position (E1); together with the abutting action exerted by the guide housing (8), the deforming shaft (1), the fourth abutting surface (34), the fifth abutting surface (35) and the sixth abutting surface (36); determining the deformation of the metal bar (7) up to obtaining a spiral (3).

Description

The present invention relates to the technical sector relating to the deformation of flat metal bars, so as to obtain spirals. In particular, the invention relates to an apparatus for deforming a metal bar up to obtaining a spiral.
A known apparatus for deforming a metal bar, up to obtaining a spiral, is illustrated in figures 1 and 2: these figures show the deformation procedure of a metal bar respectively in two successive time instants. The known apparatus comprises: a deforming shaft (1) which is drawn in rotation by first motor means (2), which deforming shaft (1) has a diameter equal to the internal diameter of the spiral (3) which is to be obtained; a guide rail (4) which develops parallel to and by the side of the deforming shaft (1); a carriage (5) that can slide along the guide rail (4), actuated by second motor means (only a drawing belt (6) is visible of the second motor means (6)); a guide housing (8) which is mounted on-board the carriage (5), which is designed to guide the sliding of a metal bar (7) which unwinds from a reel (not visible). The procedure for obtaining a spiral (3) starting from the metal bar (7) is the following: initially, the metal bar (7) is engaged in the guide housing (8) and the free end of the metal bar (7) is welded to the deforming shaft (1) (in particular, the metal bar (7) is welded to a metal body (9) having a parallelepiped shape which in turn is fixed to the deforming shaft (1)); the activating of the first motor means (2) and the second motor means causes the unwinding of the metal bar (7) from the reel and the winding of the metal bar (7) about the deforming shaft (1), with a consequent formation of a spiral (3) which can extend up to the whole length of the deforming shaft (1); lastly, the spiral (3) is cut at both ends in order to free it from the deforming shaft (1) and for separating it from the reel, and then the spiral (3) thus-obtained by the deforming shaft (1) is removed, which removal requires a free space at least equal to the length of the deforming shaft (1).
A drawback of this apparatus consists in the fact that the longer the spiral to be obtained, the more voluminous the apparatus is: in fact, if the spiral to be obtained is for example ten metres long, then the deforming shaft will have to be of about the same length. An apparatus can be realised having a deforming shaft that is shorter with respect to the length of the spiral that is to be obtained, but in that case it will be necessary to realise two or more intermediate spirals rather than one and join them by welding, which would significantly extend the time needed for obtaining the spiral of the desired length. Further, as already specified, it is also necessary to maintain a free space in front of the deforming shaft of another ten metres in order to be able to extract the spiral, and this constitutes a further drawback.
Another drawback of this apparatus consists in the fact that it is not possible to use metal bars that are too slim: in other words, there exists a lower limit in the ratio between thickness and width of the metal bar, below which a spiral would not be obtained, or a deformed spiral would be obtained. To give some examples: if the metal bar has a thickness of 3mm, the advisable width must not exceed 25mm, in some cases it could reach 30mm, but with the risk of obtaining a deformed spiral; if the metal bar is 4mm thick, the advisable width is comprised between 30mm and 40mm; if the metal bar has a thickness of 5mm, the advisable width must not exceed 50mm (for a metal bar having a 50mm width it would be better to have a thickness of 7-8mm). In other words, we can state that the thickness-width ratio must not be lower than 0.1.
The aim of the present invention consists in obviating the above-mentioned drawbacks.
The above-mentioned aims are obtained by an apparatus for deforming a metal bar up to obtaining a spiral, according to claim 1.
The volume of the apparatus is advantageously much more modest due to the fact that it performs only rotary movements (rotation of the first rotating member and the second rotating member; a gripping of the metal bar by the first rotating member and the second rotating member, and a disengagement of the first rotating member and the second rotating member of the metal bar), while the apparatus of the prior art also performs linear movements (the carriage slides along the guide) and this requires the use of a deforming shaft and a guide for the guide rail having an extension at least equal to the length of the spiral that is to be obtained.
Further, with the apparatus of the invention the deformation of the metal bar, which is carried out at the relative first portion and second portion, is constantly guided by the abutting action exerted by the guide housing, the deforming shaft, the fourth abutting surface, the fifth abutting surface and the sixth abutting surface; in the prior art apparatus, on the other hand, the deformation of the metal bar was guided by only the guide housing and the deforming shaft, which in some cases (for slim metal bars, i.e. having a thickness-width ratio of less than 0.1) did not enable obtaining a spiral or caused the formation of a deformed spiral.
Specific embodiments of the invention will be described in the following part of the present description, according to what is set down in the claims and with the aid of the appended tables of drawings, in which:

figures 1, 2 are partial perspective views of an apparatus of known type for deforming a metal bar, up to obtaining a spiral, respectively in two successive time instants of the process of deformation of the metal bar;
figure 3 is an exploded view of an apparatus for deforming a metal bar up to obtaining a spiral, object of the present invention;
figure 4 is a view of the transversal section of the apparatus of figure 3;
figures 5-14 illustrate a procedure for deforming a metal bar up to obtaining a spiral by means of the apparatus of figure 2;
figures 5A and 5B are the views respectively of sections A-A and B-B of figure 5.

With reference to the appended tables of drawings, reference numeral (10) denotes in its entirety the apparatus of the present invention for deforming a metal bar up to obtaining a spiral.
In figures 5-14, 5A, 5B the same reference numerals will be used for characteristics already mentioned in figures 1, 2.
The metal bar (7) is preferably flat and comprises (see in particular figures 5, 5A, 5B) a first longitudinally-developing surface (11), a second longitudinally-developing surface (12) which is opposite the first longitudinally-developing surface (11), a first flank (21) and a second flank (22) which is opposite the first flank (21). The metal bar (7) preferably has a rectangular transversal section.
The apparatus (10) comprises: a frame (not visible) and a guide housing (8) for the metal bar (7). The guide housing (8) is fixed to the frame and comprises: a first abutting surface (31) (figures 5A, 13, 14) for abutting the first longitudinally-developing surface (11) of the metal bar (7); a second abutting surface (32) (fig.5B, 13, 14) for abutting the second longitudinally-developing surface (12) of the metal bar (7); and a third abutting surface (33) (fig.5B, 13, 14) for abutting the first flank (21) of the metal bar (7). The guide housing (8) is dimensioned such as to enable sliding there-along of the metal bar (7) in a constant orientation: for example, the guide housing (8) has the shape of a lining open at both ends, as illustrated in the figures (see for example figures 5, 5B), or has the shape of a lining open at both ends and at a side (taking on a C-shape, a variant that is not illustrated).
The apparatus (10) further comprises: a first rotating member (41) which is actuable for rotating in both rotation directions about a rotation axis (A) (see figure 4) and within a first angle (not indicated), and which comprises a first gripping surface (51) (see figures 3, 4, 5) of the metal bar (7); a second rotating member (42) which is actuable for rotating in both rotation directions about the rotation axis (A) and within a second angle (not indicated), and which comprises a second gripping surface (52) (see figure 4) of the metal bar (7). The first rotating member (41) and the second rotating member (42) are positionable such that when the metal bar (7) engages in the guide housing (8) and exits therefrom by a predetermined length, the first and second rotating members (41, 42) can grip the metal bar (7), so that the first gripping surface (51) contacts the first longitudinally-developing surface (11) of the metal bar (7) and the second gripping surface (52) contacts the second longitudinally-developing surface (12) of the metal bar (7).
The apparatus (10) further comprises a deforming shaft (1) that is positioned so as to contribute to the deformation of the metal bar (7), by abutting the second flank (22) of the metal bar (7) (see for example figures 7 and 8) when the metal bar (7): is engaged in the guide housing (8); is gripped between the first rotating member (41) and the second rotating member (42); and is drawn in rotation by the first rotating member (41) and the second rotating member (42) in a first rotation direction (G).
The apparatus (10) further comprises a fourth abutting surface (34) (see in particular figure 4) which projects from the lateral surface of the deforming shaft (1) so as to abut the second longitudinally-developing surface (12) of a first portion (7A) of the metal bar (7) at a first spatial region (S1) (see for example figures 6, 7, 8) in which the first portion (7A) of the metal bar (7) is arranged between the guide housing (8), on one side, and the first gripping surface (51), and the second gripping surface (52), on another side, when the metal bar (7) is engaged in the guide housing (8), is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42) in the first rotation direction (G).
The apparatus (10) further comprises a fifth abutting surface (35) (see for example figures 3, 5) which is facing the fourth abutting surface (34) so as to abut the first longitudinally-developing surface (11) of the first portion (7A) of the metal bar (7) at the first spatial region (S1) in which the first portion (7A) of the metal bar (7) is arranged between the guide housing (8), on one side, and the first gripping surface (51) and the second gripping surface (52), on the other side, when the metal bar (7) is engaged in the guide housing (8), it is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42) in a first rotation direction (G).
The apparatus (10) further comprises a sixth abutting surface (36) (see for example figures 3, 5, 6, 10) which projects from the lateral surface of the deforming shaft (1) which is orientated in an opposite direction to the fourth abutting surface (34), which is distanced from the fourth abutting surface (34) by a distance that is substantially equal to a pitch of the spiral (3) to be obtained by the deformation of the metal bar (7) and which is conformed so as to abut the first longitudinally-developing surface (11) of a second portion (7B) of the metal bar (7) at a second spatial region (S2) (see figures 10-14) in which the second portion (7B) of the metal bar (7) is arranged downstream of the first gripping surface (51) and the second gripping surface (52) with respect to the first rotation direction (G) of the first rotating member (41) and the second rotating member (42), when the metal bar (7) engages in the guide housing (8), the metal bar (7) is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42).
The apparatus (10) is configured for carrying out a plurality of operating cycles, each comprising: the gripping of the metal bar (7) by the first rotating member (41) and the second rotating member (42) at a first angular position (E1), the activating of the first rotating member (41) and the second rotating member (42) in the first rotation direction (G) up to reaching a second angular position (E2), the disengaging of the first rotating member (41) and the second rotating member (42) from the metal bar (7), the actuating of the first rotating member (41) and the second rotating member (42) in a second rotation direction (not indicated in the figures), opposite the first, up to the first angular position (E1). The carrying out of the operating cycles, together with the abutting action exerted by the guide housing (8), the deforming shaft (1), the fourth abutting surface (34), the fifth abutting surface (35) and the sixth abutting surface (36), determine the deformation of the metal bar (7) up to obtaining a spiral (3).
The deforming shaft (1) is preferably coaxial to the rotation axis (A).
The apparatus (10) preferably comprises a guide member (13) which is fixed to the deforming shaft (1), which projects from the deforming shaft (1) and which incorporates the fourth abutting surface (34) and the sixth abutting surface (36).
The guide member (13) is preferably: it shaped as a strip and comprises a third flank (23); it is fixed to the deforming shaft (1) via the third flank (23) (see figures 4, 10), so that the guide member (13) partially winds about the deforming shaft (1); it has an end that forms a bevel (14) (see for example figure 10) for connecting with the sixth abutting surface (36).
The presence of the bevel (14) facilitates the sliding of the metal bar (7) in deformation along the sixth abutting surface (36).
The first rotating member (41) preferably further incorporates the fifth abutting surface (35).
The second rotating member (42) is preferably borne by the first rotating member (41).
The second rotating member (42) can form a clamp with the first rotating member (41).
The second rotating member (42) can be removably fixable to the first rotating member (41), for example by means of two screws (15, 16) (see for example figures 3, 6, 7).
The deforming shaft (1) is preferably solidly constrained to the first rotating member (41).
The first rotating member (41) preferably has a first through-hole (61) (figure 3) dimensioned such as to receive the deforming shaft (1).
The first rotating member (41) and the second rotating member (42) can be actuated manually by an operator or automatically by pneumatic or hydraulic means (not indicated).
Reference will now be made to an apparatus (10) which incorporates the embodiments mentioned in the foregoing, in accordance with figures 3-14.
With specific reference to figures 3, 4, the apparatus (10) further comprises: a base (16) which is solidly constrained to the frame and which has a disc shape having a second axial through-hole (62); a rise (17) which is fixed to the base (16), which has a parallelepiped shape and to which the guide housing (8) is fixed; a support cylinder (18) which is provided at the base of a circular abutting edge (19) projecting in a radial direction, which is provided with a third axial through-hole (63) and which is positionable resting above the base (16) so that the third axial through-hole (63) is aligned with the second axial through-hole (62); an annular crown (20) that is dimensioned for internally receiving the support cylinder (18) which is provided at the base of a circular recess (27) for receiving the circular abutting edge (19), and which is fixable to the base (16), by means of a first group of four screws (28) which pass through the base (16), so that the support cylinder (18) can remain constrained to the annular crown (20) with ability to rotate only with respect to the rotation axis (A).
The support cylinder (18) also comprises four through-holes (29) for screws, spaced so that when the support cylinder (18) is resting on the base (16), the four through-holes (29) are accessible through the second axial through-hole (62) of the base (16).
The first rotating member (41) is fixable to the support cylinder (18) by means of a second group of screws (30) which is inserted through the second axial through-hole (62) of the base (16) and passes through the four through-holes (29) of the support cylinder (18).
The apparatus (10) also comprises a first lever (81) fixable to the first rotating member (41) for actuating the first rotating member (41) in rotation; in place of the first lever (81) it is possible to use a first pneumatic cylinder (not illustrated).
The deforming shaft (1) is provided at an opposite end to the end provided with the guide member (13) of an axial threaded hole (43). The deforming shaft (1) is constrained to the assembly comprising the support cylinder (18) and the first rotating member (41) by means of a washer (44) and an adjusting screw (45): the adjusting screw (45) is inserted through the second through-hole (62) of the base (16) and the third through-hole (63) of the support cylinder (18) so as to screw into the axial through-hole (43), while the washer (44) is priorly interposed between the head of the adjusting screw (45) and the bottom of the support cylinder (18). By screwing and unscrewing the adjusting screw (45) it is possible to regulate the fourth abutting surface (34) of the guide member (13) with respect to the fifth abutting surface (35) of the first rotating member (41).
The deforming shaft (1) further comprises a recess (46) below the guide member (13) and at the relative lateral surface.
The first rotating member (41) further comprises a fourth through-hole (64) (this can be viewed in figure 3) which opens into the first through-hole (61) and which is transversal thereto.
The apparatus (10) further comprises a key (47) that can be inserted in the fourth through-hole (64) and engaged in the recess (46) of the deforming shaft (1), so as to prevent the deforming shaft (1) from rotating with respect to the first rotating member (41); in this way, the deforming shaft (1) is substantially solidly constrained to the first rotating member (41).
Specific reference will now be made to figures 5-14, for describing the procedure for deforming the metal bar (7) up to obtaining a spiral (3).
With reference to figure 5, the metal bar (7) engages in the guide housing (8), which in this case is shaped as a lining open at the ends; the guide housing (8) also comprises a seventh abutting surface (37) (figures 5B, 13, 14) which is opposite the third abutting surface (33) and which is suitable for abutting the second flank (22) of the metal bar (7). The metal bar (7) can be unwound from a reel, not illustrated. The metal bar (7) has the pointed free end: this facilitates the initial deformation of the metal bar (7) but is not essential for the good functioning of the apparatus (10) of the invention. The metal bar (7) abuts the fifth abutting surface (35), incorporated in the first rotating member (41), and the fourth abutting surface (34), incorporated in the guide member (13). The second rotating member (42) has been removed to better illustrate the pointed end of the metal bar (7) and the guide member (13). As can be noted, the first rotating member (41) is provided with two threaded holes (48) for receiving the fastening screws (15, 16) for removably fixing the second rotating member (42) to the first rotating member (41). Instead of using a manual removable fastening of the second rotating member (42) to the first rotating member (41), it is possible to use a second pneumatic cylinder (not illustrated).
In a following step, see figure 6, the second rotating member (42) is removably fixed to the first rotating member (41) by means of the two screws (15, 16) which pass through two through-holes (49) (figure 3) of the second rotating member (42) for screwing into the two threaded holes (48) of the first rotating member (41). The metal bar (7) is thus gripped by the first rotating member (41) and the second rotating member (42) at the first angular position (E1). The first rotating member (41) and the second rotating member (42) are therefore in the first angular position (E1).
The second rotating member (42) preferably has an end portion (50) which is conformed as an arc of circumference having dimensions such as to substantially match with a corresponding portion of the guide member (13), so as to enable maximising contact of the second longitudinally-developing surface (12) of the metal bar (7) with the fourth abutting surface (34) of the guide member (13) and with the second gripping surface (52) of the second rotating member (42). This enables even more efficiently controlling the deformation of the metal bar (7).
Thereafter, the operator activates the first lever (81) in the first rotation direction (G) (figure 7), moving the first rotating member (41) and the second rotating member (42) from the first angular position (E1) to the second angular position (E2). Then the fastening screws (15, 16) of the second rotating member (42) to the first rotating member (41) are partially unscrewed for disengaging the second rotating member (42) from the first rotating member (41), and the operator actuates the first lever (81) in the second rotation direction (as mentioned, this is not shown in the figures) up to the first angular position (E1). In this initial step, in which the metal bar (7) is not yet wound about the deforming shaft (1), the angular excursion between the first angular position (E1) and the second angular position (E2) is reduced, as only the end of the metal bar (7) is to be bent about the deforming shaft (1). A certain number of cycles of this type are carried out, i.e. distinguished by a small angular excursion, up to obtaining a deformation of the metal bar (7) as illustrated in figure 8.
As the end of the metal bar (7) is progressively bent about the deforming shaft (1), the operator modifies the first angular position (E1) and the second angular position (E2), thus increasing the angular excursion: this is demonstrated in figures 9 and 10.
When the end of the metal bar (7) brushes the bevel (14) of the guide member (13), a second lever (53) (e.g. a crowbar, see figures 11) can be used to bend the end of the metal bar (7), so that it can go to rest on the sixth abutting surface (36) of the guide member (13) as the metal bar (7) is progressively deformed. The use of the second lever (53) can be avoided by appropriately dimensioning the guide member (13); in other words, the guide member (13) can be conformed so that the metal bar (7) goes to rest directly, as it is progressively deformed, on the sixth abutting surface (36) without the aid of external forces.
Thereafter, the steps illustrated in figures 12 and 13 are cyclically repeated, progressively obtaining a spiral (3) of the desired length, see figure 14.
It is understood that the foregoing has been described by way of nonlimiting example, so that any constructional variants are to be taken to fall within the protective scope of the present technical solution, as claimed in the following.

Claims

An apparatus (10) for deforming a metal bar (7) up to obtaining a spiral (3), in which the metal bar (7) is flat and comprises a first longitudinally-developing surface (11), a second longitudinally-developing surface (12) which is opposite the first longitudinally-developing surface (11), a first flank (21) and a second flank (22) which is opposite the first flank (21), wherein the apparatus (10) comprises:
a frame;

a guide housing (8) for the metal bar (7), which guide housing (8): comprises a first abutting surface (31) for abutting the first longitudinally-developing surface (11) of the metal bar (7); comprises a second abutting surface (32) for abutting the second longitudinally-developing surface (12) of the metal bar (7); comprises a third abutting surface (33) for abutting the first flank (21) of the metal bar (7); and is dimensioned such as to enable sliding there-along of the metal bar (7) in a constant orientation;

a deforming shaft (1);

the apparatus (10) being characterised in that:
the guide housing (8) is fixed to the frame;

it comprises a first rotating member (41) which is actuable for rotating in both rotation directions about a rotation axis (A) and within a first angle, and which comprises a first gripping surface (51) of the metal bar (7);

it comprises a second rotating member (42) which is actuable for rotating in both rotation directions about the rotation axis (A) and within a second angle, and which comprises a second gripping surface (52) of the metal bar (7); the first rotating member (41) and the second rotating member (42) being positionable such that when the metal bar (7) engages in the guide housing (8) and exits therefrom by a predetermined length, the first and second rotating members (41, 42) can grip the metal bar (7) so that the first gripping surface (51) contacts the first longitudinally-developing surface (11) of the metal bar (7) and the second gripping surface (52) contacts the second longitudinally-developing surface (12) of the metal bar (7);

in that the deforming shaft (1) is positioned so as to contribute to the deformation of the metal bar (7), by abutting the second flank (22) of the metal bar (7) when the metal bar (7): is engaged in the guide housing (8), is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42) in a first rotation direction (G);

in that it comprises a fourth abutting surface (34) which projects from the lateral surface of the deforming shaft (1) so as to abut the second longitudinally-developing surface (12) of a first portion (7A) of the metal bar (7) at a first spatial region (S1) in which the first portion (7A) of the metal bar (7) is arranged between the guide housing (8), on one side, and the first gripping surface (51), and the second gripping surface (52), on another side, when the metal bar (7) is engaged in the guide housing (8), is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42) in the first rotation direction (G);

in that it comprises a fifth abutting surface (35) which is facing the fourth abutting surface (34) so as to abut the first longitudinally-developing surface (11) of a first portion (7A) of the metal bar (7) at the first spatial region (S1) in which the first portion (7A) of the metal bar (7) is arranged between the guide housing (8), on one side, and the first gripping surface (51), and the second gripping surface (52), on another side, when the metal bar (7) is engaged in the guide housing (8), it is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42) in the first rotation direction (G);

in that it comprises a sixth abutting surface (36) which projects from the lateral surface of the deforming shaft (1) which is orientated in an opposite direction to the fourth abutting surface (34), which is distanced from the fourth abutting surface (34) by a distance that is substantially equal to a pitch of the spiral (3) to be obtained by the deformation of the metal bar (7) and which is conformed so as to abut the first longitudinally-developing surface (11) of a second portion (7B) of the metal bar (7) at a second spatial region (S2) in which the second portion (7B) of the metal bar (7) is arranged downstream of the first gripping surface (51) and the second gripping surface (52) with respect to the first rotation direction (G) of the first rotating member (41) and the second rotating member (42), when the metal bar (7) engages in the guide housing (8), the metal bar (7) is gripped between the first rotating member (41) and the second rotating member (42) and is drawn in rotation by the first rotating member (41) and the second rotating member (42);

the apparatus (10) being configured such that:
a carrying-out of a plurality of operating cycles each comprising: the gripping of the metal bar (7) by the first rotating member (41) and the second rotating member (42) at a first angular position (E1), the activating of the first rotating member (41) and the second rotating member (42) in the first rotation direction (G) up to reaching a second angular position (E2), the disengaging of the first rotating member (41) and the second rotating member (42) from the metal bar (7), the actuating of the first rotating member (41) and the second rotating member (42) in a second rotation direction, opposite the first, up to the first angular position (E1);

together with the abutting action exerted by the guide housing (8), the deforming shaft (1), the fourth abutting surface (34), the fifth abutting surface (35) and the sixth abutting surface (36);

determine the deformation of the metal bar (7) up to obtaining a spiral (3).
The apparatus (10) of the preceding claim, wherein the deforming shaft (1) is preferably coaxial to the rotation axis (A).
The apparatus (10) of claim 1 or 2, wherein it comprises a guide member (13) which is fixed to the deforming shaft (1), which projects from the deforming shaft (1) and which incorporates the fourth abutting surface (34) and the sixth abutting surface (36).
The apparatus (10) of the preceding claim, wherein the guide member (13): it is shaped as a strip and comprises a third flank (23); it is fixed to the deforming shaft (1) via the third flank (23), so that the guide member (13) partially winds about the deforming shaft (1); it has an end that forms a connecting bevel (14) with the sixth abutting surface (36).
The apparatus (10) of any one of the preceding claims, wherein the first rotating member (41) further incorporates the fifth abutting surface (35).
The apparatus (10) of any one of the preceding claims, wherein the second rotating member (42) is borne by the first rotating member (41).
The apparatus (10) of any one of the preceding claims, wherein the deforming shaft (1) is solidly constrained to the first rotating member (41).
The apparatus (10) of any one of the preceding claims, wherein the first rotating member (41) has a first through-hole (61) dimensioned such as to receive the deforming shaft (1).
The apparatus (10) of any one of the preceding claims, wherein the guide housing (8) has the shape of a lining open at both ends, or has the shape of a lining open at both ends and at a side.
The apparatus (10) of any one of the preceding claims, wherein the second rotating member (42) is removably fixed to the first rotating member (41).
The apparatus (10) of any one of the preceding claims, wherein the second rotating member (42) forms a clamp with the first rotating member (41).