EP0198779B1 - Drawing device for forming a tube starting from a metal strip - Google Patents

Description

The present invention relates to a die device for forming a tube from a metal strip.

The technical sector of the invention is that of tools used in the manufacture of tubular objects, in particular jewelry or similar articles.

We know the dies with which we stretch the metal in order to transform it into a wire of a given section.

Devices are also known for manufacturing tube by rolling by means of forming rollers.

Machines are still known for forming tube elements by means of a die.

US-A-2 229 149 relates to a machine according to the preamble of claim 1 for manufacturing ornamental chains, Patent DE-C-597,120 relates to a device for manufacturing tubes from sheet metal, but these patents use techniques different from that proposed by the present invention.

The objective to be achieved is the manufacture of straight or curved tubes, from a metal ribbon or an alloy of common or precious metals, produced in a single pass by pulling said ribbon by means of a tool ensuring the joining of turned edges of the ribbon in a perfectly straight line.

Another objective is to produce a tube by mechanical traction of the ribbon being formed in order to obtain tube wound in a circular, oval or other manner ...

These objectives are achieved by the die device according to the invention for forming a tube from a metal strip comprising a die block comprising a longitudinal duct having an inlet opening of larger section and an outlet opening of more small section and the generators of which converge from the inlet orifice to the outlet orifice, the ribbon of which is passed through said conduit with a view to its transformation into a tube, which comes from said outlet orifice in the form of this orifice and under the effect of a traction exerted on the strip being transformed, characterized in that said die block comprises a guide fin extending over all or part of the length of the duct and protruding inside thereof, which fin is parallel to the longitudinal axis of said duct and has the function of guiding the turned edges of the metal strip during its pulling view of obtaining the joining of said edges in a perfectly rectilinear manner.

According to an embodiment of which said block is of a polygonal cross section and whose inlet orifice and outlet of the duct opens onto two plane faces parallel to each other and perpendicular to the longitudinal axis of said block, said guide fin originates at the periphery of the outlet orifice and is of zero height at the right of this orifice and extends towards the inside of the duct progressing in height, the longitudinal edge of the aileron being substantially perpendicular to said flat faces of the block where said orifices open out.

According to another embodiment, the die block comprises inside the duct, a guide rod constituting a fixed core, coaxial with the duct and carried by a support plate fixed to the part of the block where the orifice opens out. 'inlet of the conduit and whose free end of said core extends slightly outside the outlet of the conduit and is of an outer contour parallel to the inner contour of said orifice, a space substantially equal to the thickness of the metallic strip being reserved between the core and the outlet opening of the conduit.

The angle formed by the wall of the conduit and the face where the outlet orifice of the die block opens is softened to avoid any metal tearing during the traction exerted on the strip.

According to the invention, in which said die block is removably mounted on a carriage movable horizontally in front of a horizontal mandrel driven in rotation by motor means and around which the mandrel winds the tube, coming from the die block, substantially perpendicularly on the face of the block where the outlet outlet of the conduit opens, the carriage is mounted pivoting about a horizontal axis parallel to the mandrel and includes means for positioning it in inclination, so that the tube issuing from the die block tangent to said mandrel.

Said drive means consist of a geared motor or a geared motor-variator fixed to a rectangular base whose output shaft of the reducer extends horizontally and said base comprises, opposite the output shaft, a fixed headstock having a point coaxial with said output shaft of the reduction gear and in that the mandrel is removably placed between said reducer and in that the mandrel is removably placed between said reducer and said headstock, is rotated by one of its ends on the output shaft of the reducer and is supported at its other end by said tip, which is mounted movable along its longitudinal axis in a horizontal housing reserved in said headstock, which comprises means for immobilizing the tip in position.

Said carriage is carried by a support mounted adjustable on the base so as to be able to be moved towards or away from the mandrel and comprises means for immobilizing it in position relative to the mandrel.

Said support consists of a base plate and two end posts perpendicular to said plate. The carriage is made up of a die-carrying plate comprising two slides which cooperate with a set of two slides which are parallel to one another and anchored in two end pieces, said set of slides being pivotally mounted around two horizontal and coaxial shafts and carried by said amounts of ends of the support.

Said set of carriage-carrier slides is mounted adjustable in height on the two uprights of the support, which uprights have holes distributed over their height and capable of receiving said shafts around which said set of slides pivots.

The means for positioning the carriage and said set of slides in inclination consist of two abutment screws screwed at the end of two support legs pivotally mounted vertically on one or the other of said support uprights and immobilizable by position, which screw-stops are brought into contact with one or the other of the end pieces in which the slides are anchored and on either side of the pivot axis of said set of slides.

Said mandrel comprises, at its periphery, a groove wound in a helix with contiguous turns and over the length of the mandrel, the cross section of the groove of which corresponds to that of the tube coming from the filling.

To produce tubular objects with an elliptical outline, the mandrel comprises a central core on which are attached two half-shells of an external semi-elliptical outline and means for assembling the half-shells and the core, which half-shells in place on said core are spaced from each other by a distance substantially equal to the width of the tube, so that after removal of the core can be released from the mandrel the tube wound in an ellipse.

For the attachment of the tube to the mandrel, the latter comprises at one of its ends, a radial mortise opening at its periphery and intended to receive a stopper for driving the tube coming from the die block, which stopper has a hole in which the tube is passed and means for fixing the tube to the cleat.

The die device according to the invention thus makes it possible to produce the tube by rolling, without elongation of the metal ribbon or of alloy of common or precious metals, with a line of junction of the turned edges of the ribbon perfectly straight, without twisting or other defect .

• la figure 1 est une vue en perspective d'un bloc de filière vu du côté de l'orifice de sortie du conduit;
• la figure 2 est une vue en perspective d'un bloc de filière vu du côté de l'orifice d'entrée du conduit;
• la figure 3 est une vue en coupe longitudinale du bloc de filière illustrant le ruban métallique formé en pointe et mis en place dans le conduit avant l'opération de tirage du ruban en vue du formage du tube;
• la figure 4 est une vue en élévation/coupe partielle d'un bloc de filière comportant un aileron pour le guidage des bords retournés du ruban;
• la figure 4bis est une vue en coupe à plus grande échelle de l'orifice de sortie du bloc de filière;
• la figure 5 est une vue suivant F du bloc de filière de la figure 4;
• la figure 6 est une vue en élévation/coupe partielle d'un bloc de filière comportant à la fois un aileron de guidage et une âme interne au conduit en vue de réaliser notamment des tubes de section carrée ou rectangulaire;
• la figure 7 est une vue suivant F₁ du bloc de filière de la figure 6;
• la figure 8 est une vue en perspective d'un dispositif de filière selon l'invention;
• la figure 9 est une vue de dessus schématique du dispositif de la figure 8;
• la figure 10 est une vue en coupe selon la ligne X X de la figure 9;
• la figure 11 est une vue en élévation d'un mandrin pour réaliser des objets selon un contour elliptique;
• la figure 12 est une vue en coupe du mandrin selon la ligne XII XII de la figure 11;
• la figure 13 est une vue en élévation partielle d'un mandrin illustrant un taquet de tirage du tube, vu en coupe et dans un mode d'exécution;
• la figure 14 est une vue en élévation partielle d'un mandrin illustrant un taquet de tirage du tube, vu en coupe et dans un autre mode d'exécution.

Other advantages and characteristics of the invention will emerge further on reading the following description of a die device with reference to the appended drawing in which:

• Figure 1 is a perspective view of a die block seen from the side of the conduit outlet;
• Figure 2 is a perspective view of a die block seen from the side of the conduit inlet;
• Figure 3 is a longitudinal sectional view of the die block illustrating the metal strip formed at the tip and placed in the conduit before the ribbon drawing operation for the forming of the tube;
• Figure 4 is an elevational / partial sectional view of a die block having a fin for guiding the turned edges of the tape;
• Figure 4bis is a sectional view on a larger scale of the outlet orifice of the die block;
• Figure 5 is a view along F of the die block of Figure 4;
• Figure 6 is an elevational view / partial section of a die block comprising both a guide fin and a core internal to the duct in order to produce in particular tubes of square or rectangular section;
• Figure 7 is a view along F₁ of the die block of Figure 6;
• Figure 8 is a perspective view of a die device according to the invention;
• Figure 9 is a schematic top view of the device of Figure 8;
• Figure 10 is a sectional view along line XX of Figure 9;
• Figure 11 is an elevational view of a mandrel for making objects along an elliptical contour;
• Figure 12 is a sectional view of the mandrel along line XII XII of Figure 11;
• Figure 13 is a partial elevational view of a mandrel illustrating a tube pulling stop, seen in section and in one embodiment;
• Figure 14 is a partial elevational view of a mandrel illustrating a tube pulling stop, seen in section and in another embodiment.

Referring first to Figures 1 and 2 of the drawing which illustrate a die block according to the invention 1 in one embodiment. This is in the form of a parallelepiped of square section.

It will be noted that said block could adopt any other external shape and thus be of any polygonal section or even be cylindrical. Said block 1 comprises, in the direction of its length, a conduit 1a comprising an inlet orifice of larger section 1b, for example circular which opens onto a face 1c of the block and an outlet orifice 1d, of smaller circular section , which opens onto another face 1e, parallel to said face 1c. The ports 1b / 1d are joined by generators 1f which converge from the inlet port 1b towards the outlet, so that the duct is of a frustoconical shape.

The die block is designed to communicate the most diverse shapes to the metal ribbon, to generate tubes of all shapes, for example of a circular, rectangular, square, triangular, star, heart-shaped or other cross section.

The shape of the tube is given by the outlet port 1d. The inlet of said block is, in one embodiment, of a circular cross section whose diameter is slightly greater than the width of the metal strip 2 which is shown in phantom in Figure 2.

In the embodiment shown in Figures 1 and 2, the die block 1 comprises on the side of the inlet 1b and applied against the face 1c of the block, two 3/4 rectangular plates, which plates are for example fixed by means of screws 5 screwed into tapped holes reserved in the die block. These plates have rectilinear edges 3a / 4a which are spaced from each other by a distance d substantially equal to the thickness of the metal strip 2.

For the implementation of the tube, the ribbon 2 is formed as a point, as illustrated in FIG. 3 and is passed between the two plates 3/4. The pointed end 2a which opens out from the outlet orifice 1d is gripped by means of pliers and the ribbon 2 is pulled manually until the die gives the ribbon the shape of the tube.

This can be obtained manually by continuing to exert traction on the metal strip or can be mechanically wound around a mandrel as will be explained below.

One of the plates, for example the plate 3, may include a notch 3b reserved on the rectilinear edge 3a, which notch adopts for example the shape of a Vee and is located in line with the longitudinal axis 1a. This notch allows the passage of a metal wire (not shown) which constitutes a core around which the metal ribbon is wound.

The two 3/4 plates have the function of guiding the ribbon 2 and of opposing its twisting during traction in order to obtain the joining of the turned edges of the ribbon in a perfectly rectilinear manner.

During the movement of the ribbon 2 in the conduit 1a, the lateral edges 2c / 2d of the tape guided by the wall of the duct are rolled towards one another to come together by exiting through the outlet orifice 1d in the desired shape of the tube which is communicated by said orifice 1d.

The die block 1 may have only one plate and the ribbon 2 is then guided by the single straight edge 3a of the plate 3.

Another embodiment of the die block according to the invention is given in Figures 4 and 5. The die block 1 is similar to that which has just been described with reference to Figures 1 and 2. According to this embodiment , the outlet orifice 1g, which opens onto the face 1e is for example of a circular cross section.

The inlet 1h, which opens on the face 1b, is of a generally elliptical section so that the duct 11 is of a generally frustoconical shape. The 1h entry orifice is such that its major axis 1h₁ is slightly larger than the width of the metal strip.

The duct 11 has a small fin 1m, for example 6/10 of a millimeter thick, which fin extends for example over part of the length of the duct 11 and protrudes inside of it. Said fin originates at the periphery of the outlet orifice 1g, is of zero height in line with said orifice and extends inwardly parallel to the axis of the duct progressing in height so that its edge longitudinal 1m₁ is substantially perpendicular to the face 1g of the die block. The purpose of this fin is to guide the upturned edges of the metal strip during the traction exerted on the strip in order to obtain the joining of said edges in a perfectly rectilinear manner.

The angle formed by the wall of the conduit 11 and the face 1e where the outlet orifice 1g opens is softened to avoid tearing of metal during the traction exerted on the strip. The outlet 1g has for this purpose a flat 1g₁ for example with a width of 8 / 10th of a millimeter and extending over the internal periphery of the orifice 1g.

Another embodiment of the die block is illustrated in Figures 6 and 7. The die block 1 is similar to those which have just been described with reference to Figures 1, 2, 4 and 5. According to this other embodiment execution, the outlet port 1n, which leads to the 1st side is for example of a rectangular cross section. The inlet 1p is of a rounded outline so that the duct 1q is of a generally frusto-conical shape.

This comprises a fin 1r in all points identical to the fin 1m described with reference to FIG. 4.

The block comprises inside the conduit 1q a guide rod 6 which constitutes a fixed core coaxial with the conduit 1q and extending approximately over the half-length of the block, which core 6 extends a rod of greater cross section 6a, fixed to a rectangular support plate 7, fixed by means of screws 8, for example 2 in number, screwed into tapped holes reserved in the block 1. The support plate 7 is applied to the face 1b where the orifice opens out entry 1q. The core 6 / 6a is perpendicular to the plate 7 and is fixed to the latter by means of screws 9.

The plate 7 is fixed on the side of the fin 1r.

The core 6 is of a rectangular cross section and has an external contour parallel to the internal contour of the outlet orifice 1n of the conduit. A space e of a value substantially equal to the thickness of the metal strip is reserved between the core 6 and the outlet orifice 1n to allow passage of the tube at the outlet of the die block. The core 6 extends slightly outside the orifice 1n. Its function is to perfectly calibrate the tube. The fin 1r makes it possible, as has already been explained above, to join the edges of the ribbon in a perfectly rectilinear manner.

Reference is now made to FIGS. 8, 9 and 10 of the drawing which illustrate a die device 10 for pulling by winding the tube coming from the die block 1.

This die device comprises a rectangular base 11 on which is mounted at one end a motor-reducer or a motor-reducer-variator 12 extending at right angles to the base 11 and projecting therefrom. In known manner, the variator comprises a control member 13 with a dial 13a which gives indications which make it possible to calibrate the machine as a function of the actual revolutions of the output shaft of the reducer. The motor is connected, by a cable 14, to a control unit 15, itself connected to the mains by another cable 16.

The output shaft 12a of the gear motor 12 is hollow and extends horizontally and parallel to the longitudinal edges 11a of the base 11.

Opposite the output shaft 12a of the reduction gear, the base 11 comprises a fixed headstock 17 in which is mounted a point 18 which is coaxial with said shaft 12a of the reduction gear. The tip 18 is mounted adjustable in the headstock 17 in a horizontal cylindrical housing 17a, which crosses the headstock in the longitudinal direction of the base 11. The point 18 extends a cylindrical axis 18a having the same diameter as the cylindrical housing 17a of the headstock 17 , which axis has a flat 18a₁. The adjustment in position of the tip 18 on the headstock 17 is obtained by means of a pressure screw 19 screwed into a tapped hole reserved for the upper part of the headstock 17.

Between the headstock 17 and the reduction gear 12, there is a removable mandrel 20, which comprises, at one end, a shaft end 20a which penetrates into the hollow shaft 12a of the reduction gear, the rotation drive being effected by the through a keyway 21. In known manner, the hollow shaft has a longitudinal groove in which is engaged a key secured to the shaft end 20a of the mandrel.

At its other end, the mandrel has a conical hole 20b into which the tip 18 of the headstock penetrates.

The mandrel 20 is of an external shape which is a function of the objects which it is desired to obtain.

For the manufacture of circular tubular rings, the mandrel 20 is cylindrical. It is smooth in the case of the manufacture of objects having a square or rectangular cross section. For the manufacture of rings of a circular cross section, it comprises, at its periphery and over its almost length, a groove wound in a helix 20c with contiguous turns, the section of which corresponds to the external dimension of the tube. This groove provides a regular winding of the tube from the die block 1.

At the height of the mandrel 20 and parallel thereto, the device comprises a set of two slides 21/22, which are horizontal and parallel to each other and are embedded in two end pieces 23/24. This assembly, which adopts the shape of a rectangle, is pivotally mounted around two horizontal and coaxial shafts 25/26, which shafts are engaged in holes 27 reserved in the two uprights 28a / 28b of a support 28, in support on the base 11. This support 28 consists of a rectangular base plate 28c at the ends of which said uprights 28a / 28b are fixed, which are perpendicular to said plate 28c.

The support is mounted to be movable so that it can be moved towards or away from the mandrel 20. To do this, the base plate 28c has two slots 28d, located on the side of the uprights 28a / 28b and perpendicular to the longitudinal edges of the plate 28c. Maintaining the support 28 in position on the base 11 is obtained by two screws 29 passed through the slots 28d and screwed into tapped holes 11b, reserved in the base 11.

The set of slides 21/22 is adjustable in height so that it can be positioned as a function of the size of the mandrel 20. This adjustment is made possible by several holes 27 distributed over the height of the uprights 28a / 28b and through which the shafts have passed. 26/27.

On the set of slides 21/22 is slidably mounted a carriage 30, which is thus horizontally movable in front of said mandrel 20. This carriage consists of a die-holder plate 30a to which two slides 30b / 30c are fixed to screw means 31. To facilitate the sliding of the carriage 30 on the slides 21/22, the slides are of the linear rolling type.

The die holder plate 30a has a square section housing 30a₁ intended to receive the die block 1 which is of a corresponding cross section.

So that the tube coming from the die block 1 which extends substantially perpendicular to the edge 1e of said block where the outlet orifice opens can tangent the mandrel, the set of slides 21/22 / carriage 30, is pivotally mounted around of said trees 26/27. The positioning in inclination of the carriage 30 and of all of the slides 21/22 is obtained by two stop screws 32/33 screwed into threads reserved for the end of two support lugs 34/35, pivotally mounted in a plane vertical around two screws 36/37 screwed into the upright 28b of the support 28.

To wedge the set of slides 21/22 and the carriage 30, the support legs 34/35 are first positioned by pivoting them around the previously loosened screws 36/37 so as to place the stop screws 32 / 33 on either side of the pivot axis of the set of slides 21/22, tighten the screws 36/37 and act on the stop screws 32/33 until stalling at the inclination desired said set of slides 21/22 carrying the carriage 30.

The tube, first formed by manual traction in the die block 1, is fixed to the mandrel 20 by means of a driving cleat, two embodiments of which are given in FIGS. 13 and 14

The mandrel 20 has at its end located on the side of the shaft end 20a, a radial mortise 20d of a rectangular cross section corresponding to that of the cleat. This 38, in the embodiment of Figure 13, is in the form of a small rectangular parallelepiped and has a hole 38a, passing right through, and through which the free end of the tube. The tube is fixed to the cleat 38 by means of a pressure screw 39.

In the embodiment of FIG. 14, the cleat 40, similar to the cleat 38, has a hole 40a passing right through it through which the tube has passed and a second hole 40b, perpendicular and adjacent to the hole 40a and in which hole 40b has passed a clamping screw 41, screwed into a tapped hole 20e made in the bottom of the mortise 20d. Under the effect of the tightening of the screw 41, the cleat is moved in the mortise 20d, which has the effect of blocking the tube between the cleat 40 and the periphery of the mandrel 20.

The gear motor is then actuated to drive the mandrel in rotation and the tube, coming from the die 1, is wound around the mandrel with contiguous turns. The free mounting on slide of the carriage 30 allows the winding of the tube over the length of the mandrel 20.

The die block 1 is kept engaged in the housing 30a₁ of the carriage under the effect of the traction exerted on the tube.

Referring now to Figures 11 and 12 of the drawing which illustrate a mandrel for making oval or elliptical objects.

In a cylindrical mandrel such as that which has just been described, no problem arises when it is necessary to remove from the mandrel the tube wound with contiguous turns. If the mandrel is smooth, simply slide the coiled tube over the mandrel.

If the mandrel has a helical groove, the withdrawal of the tube is obtained by "unscrewing" the tube winding.

On the other hand, a problem exists when the mandrel is of an elliptical or oval cross section and the tube is wound in a groove because the wound tube cannot be removed if the mandrel is made in one piece.

According to the invention and to produce tube windings of an ovalized or elliptical outline, the mandrel 42 consists of a core for example cylindrical 42a comprising at one end a shaft end 42b engaged in a bore 42c and pinned by means of a mechanical pin 43 engaged in holes 42d / 42e extending diametrically to the core 42a and at the shaft end 42b . At its other end, the core has a coaxial conical housing 42f. The mandrel also comprises two half-shells 42₁ / 42₂ of an external contour, for example substantially semi-elliptical and of an internal contour substantially semi-cylindrical, so as to adapt perfectly to the cylindrical core 42a. The two half-shells are in opposition so that, as shown in FIG. 12, the mandrel is of an elliptical cross section. They extend over the almost length of the core 42a and comprise, at their ends, semi-annular shoulders with an outer substantially semicircular contour 42a₁ / 42₁b - 42₂a / 42₂b. The assembly of the two half-shells 42₁ / 42₂ on the core 42a is carried out by means of a pin 44, engaged free in a cylindrical conduit 42g, extending diametrically to the core 42a and corresponding with two holes 42h / 42j reserved in the annular shoulders 42₁a / 42₂a. A ring 45, comprising a first bore 45a, of a diameter slightly greater than the diameter of the core 42a and a second concentric bore 45b slightly greater than the external diameter of the shoulders 42₁a / 42₂a, has the function of maintaining both the two half shells and hold the pin 44.

The depth of the bore 45b is substantially equal to the length of said shoulders.

A second ring 46, identical to the ring 45, overlaps the shoulders 42₁b / 42₂b. This ring 46 has a bore 46a of a diameter slightly greater than that of the core 42a and a second concentric bore 46b, slightly greater than the external diameter of the shoulders 42 _1b / 42₂b.

The ring 46 is held in position by a pressure screw 47, screwed into a tapped radial hole 46c and coming to bear on the core 42a. Likewise, the ring 45 is held by a screw 48 screwed into a tapped radial hole 45c and bearing on the core 42a.

The two half-shells 42₁ / 42₂ are spaced from each other by a distance d₁ substantially equal to the width of the tube, for example for a cylindrical tube: its diameter.

They comprise, at their periphery, a helical groove 42₁c / 42₂c in which is wound the tube from the die block 1.

To remove the winding of the tube from the mandrel 42, the screw 47 is loosened and the ring 46 is made to slide on the core until the shoulders 42₁b / 42₂b are released. The screw 48 is then loosened and the other ring 45 is slid to release the shoulders 42 /a / 42₂a from the half-shells and the pin 44 which falls by gravity escapes. The core 42a is removed by sliding it relative to the half-shells 42₁ / 42₂. The said half-shells are then brought closer until their longitudinal edges 42₁d / 42₂d come into contact with one another and the tube winding is removed.

One of the half-shells 42₁ includes a radial mortise 42₁d to place therein one of the drive lugs 38/40 described with reference to FIGS. 13 and 14.

Claims (14)

1. Die device for forming tube from a metal band (2), which comprises a die block (1) comprising a longitudinal conduit (1a/11/1q) having an inlet orifice (1b/1h/1p) of larger section and an outlet orifice (1d/1g/1n) of smaller section and of which the generatrices converge from the inlet orifice towards the outlet orifice of which the band (2) is passed through said conduit with a view to being transformed into tube, which tube issues from said outlet orifice (1d,1g,1n) with the shape of said orifice and under the effect of a traction exerted on the band during transformation thereof, characterized in that said die block (1) comprises a guide fin (1m/1r) extending over all or part of the length of the conduit (1a/111q) and projecting thereinside, which fin (1m/1r) is parallel to the longitudinal axis of said conduit and having the function of guiding the turned up edges of the metal band (2) during the traction with a view to obtaining a perfectly rectilinear join of said edges.
2. Die device according to claim 1, of which said block (1) is of polygonal cross-section and of which the inlet orifice (1b/1h/1p) and the outlet orifice (1d/1g/1n) of the conduit open out on two plane faces (1c/1e) parallel to each other and perpendicular to the longitudinal axis of said block, characterized in that said guide fin (1m) starts at the periphery of the outlet orifice of the conduit (1g), is of zero height at the level of said orifice, and extends inside the conduit while progressing in height, the longitudinal edge (1m₁) of said fin being substantially perpendicular to said plane faces (1c/1e) of the block where said orifices open out.
3. Device according to any one of claims 1 or 2, characterized in that the die block (1) comprises, inside the conduit (1q), a guide rod constituting a fixed core (6), coaxial to the conduit (1q) and borne by a support plate (7) fixed to that part (1b) of the block where the inlet orifice (1p) of the conduit opens out, which core (6) has an outer contour parallel to the inner contour of said outlet orifice (1n), a space substantially equal to the thickness of the metal band being provided between the core and the outlet orifice (1n) of the conduit (1q).
4. Die device according to claim 3, characterized in that the free end of said core (6) extends slightly outside the outlet orifice (1n) of the conduit (1q).
5. Die device according to any one of claims 3 and 4, characterized in that the angle formed by the wall of the conduit (11) and the face (1e) where the outlet orifice (1g) opens out is softened in order to avoid any tear of metal during the traction exerted on the band (2).
6. Die device according to any one of claims 1 to 5, of which the die block (1) is removably mounted on a carriage (30) movable horizontally in front of a horizontal mandrel (20) driven in rotation by drive means and about which mandrel (20) is wound the tube, issuing from the block (1e) where the outlet orifice (1d/1g/1n) of the conduit opens out, characterized in that said carriage (30) is mounted to pivot about a horizontal axis parallel to the mandrel (20) and comprises means (32/33/34135/36/37) for positioning it in inclination, so that the tube issuing from the die block (1) is tangential to said mandrel (20).
7. Die device according to claim 6, comprising a reduction gear motor or reduction gear motor/variable speed drive unit (12) fixed to a rectangular base (11) of which the driven shaft (12a) of the reduction gear extends horizontally, characterized in that said base (11) comprises, opposite the driven shaft (12a) of the reduction gear, a fixed headstock (17) comprising a tip (18) coaxial to said driven shaft (12a) Of the reduction gear and in that the mandrel (20) is removably placed between said reduction gear (12) and said headstock (17) and is fixed in rotation by one of its ends on the driven shaft (12a) of the reduction gear and is supported at its other end by said tip (18), which is mounted to move along its longitudinal axis in a horizontal housing (17a) provided in said headstock (17), which comprises means (19) for immobilizing the tip (18) in position.
8. Die device according to any one of claims 6 and 7, characterized in that said carriage (30) is borne by a support (29) mounted adjustably on said base (11) so as to be moved towards or away from the mandrel (20) which support further comprises means (28d/29) for immobilizing it in position with respect to the mandrel (20).
9. Die device according to any one of claims 6 to 8, characterized in that said support (28) is composed of a base plate (28c) and of two end uprights (28a/28b) perpendicular to said plate (28c) and in that the carriage (20) is composed of a die-holder plate (30a) comprising two sliding elements (30b/30c) which cooperate with an assembly of two slide rails (21/22) parallel to each other and anchored in two end pieces (23/24), said slide rail assembly (21/22) being mounted to pivot about two horizontal, coaxial shafts (25/26) borne by said end uprights (28a/28b) of the support (28).
10. Die device according to claim 9, characterized in that said carriage-holder (30) slide (21/22) assembly is mounted to be adjustable in height on the two uprights (28a/28b) of the support (28), which uprights comprise holes (27) distributed over their height and, capable of receiving said shafts (25/26) about which said slide rail assembly (21/22) pivots.
11. Die device according to any one of claims 6 to 9, characterized in that the means for positioning the carriage (30) and said slide assembly (21/22) in inclination consist in two stop screws (32/33) screwed at the end of two support tabs (34/35) mounted to pivot in the vertical direction on one or the other of said uprights (28a/28b) of the support and adapted to be immobilized in position, which stop screws (32/33) are placed in contact with one or the other of the end pieces (23/24) in which the slide rails (21/22) are anchored and on either side of the pivot axis of said slide assembly (21/22).
12. Die device according to any one of claims 6 to 11 for making tubular objects with an elliptic contour, characterized in that the mandrel (42) comprises a central core (42a) on which are added two half-shells (42₁/42₂) with semi-elliptic outer contour and means (44/45/46/47) for assembling the half-shells (42₁/42₂) and the core (42a), which half-shells (42₁/42₂), in place on said core (42a), are spaced apart from each other by a distance (d1) substantially equal to the width of the tube, so that, after removal of the core (42a), the elliptically wound tube may be removed from the mandrel.
13. Die device according to claim 12, characterized in that the mandrel (42) comprises, on its periphery, a groove (42_1c/42_2c) provided on said half-shells (42₁-42₂) helically wound with contiguous turns and over the length of the mandrel, of which the cross-section of the groove (42_1c/42_2c) corresponds to that of the tube issuing from the die (1).
14. Die device according to any one of claims 6 or 12 or 13, characterized in that the mandrel (20/42) comprises at one of its ends a radial mortise (20d/42₁d) opening on its periphery and adapted to receive a catch (38/40) for driving the tube issuing from the die block (1), which catch (38/40) comprises a hole (38a/40a) in which the tube is passed and means (39/41) for fixing the tube to the catch (38/40).

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