EP2012945B1 - Device for bending tubes or profiled sections with symmetrical structure for two-way bending and machine equipped with same - Google Patents

Description

The present invention relates to a new device for bending tubes or profiles and a machine comprising this device, (see for example EP-A-1226 887 ).

The invention relates particularly but not exclusively to the so-called winding-voltage bending technique whose principle is recalled here in connection with the Figures 1 to 3 .

A tube (A) is immobilized on a bending form (B) by a jaw (C).

The assembly (jaw-jaw form) is rotated, a strip (D) or rollers (E) maintain the tube (A) in the axis of the machine.

It is the most used technique for manufacturing industrial parts.

It allows short-radius bending (factor R 0.8) of thin-walled tubes (factor E of 200).

The quality and precision of the parts made with this technique are dependent on the maintenance of the tube by the jaw on the bending form.

• Création de plis à l'intrados (F) (ou intérieur)du cintre,
• Altération des parties droites (G) entre cintres, d'où une dégradation de la géométrie des pièces.

Any slip causes two effects:

• Creation of folds on the intrados (F) (or inside) of the hanger,
• Alteration of the straight parts (G) between hangers, hence a deterioration of the geometry of the pieces.

In order to be effective, the clamping jaws must have sufficient clamping force and high rigidity to transmit the clamping force.

On existing machines, the movement is achieved either by a cylinder (hydraulic or pneumatic) associated with a mechanical system generally a toggle system, or by a motor (electric) associated with a screw-nut system.

This assembly is mounted on a bending arm rotating around the bending form.

The design of thin-walled tube parts is currently "constrained" by the capacity of the means available on the market to link with more or less difficulty bending in the clockwise direction (see figure 4 ) and counter-clockwise bends (see figure 5 ).

• réaliser les deux sens de cintrage avec un équipement disposant de deux têtes de cintrages dont le principe est représenté à la figure 6. Le tube est successivement cintré dans un premier sens par une première tête (a) de cintrage puis en sens contraire par passage dans une deuxième tête de cintrage (b).
• réaliser les deux sens de cintrage avec un équipement comportant deux outils (c, d) montés de part et d'autre d'une tête de cintrage, et dont le principe est représenté en figure 7. Les deux outils (c, d) sont montés sur le même axe (e) de cintrage, le changement de sens de cintrage nécessite une combinaison complexe de mouvements.
• réaliser les deux sens de cintrage avec deux outils (f, g) à axes de rotation commutables selon le principe de la figure 8. Dans ce cas, la commutation du sens de cintrage est très rapide, mais la mécanique est complexe. De plus, cette solution ne permet pas de changement de rayon de cintrage.
• réaliser les deux sens de cintrage avec deux outils (h, i) situés sur des plans différents selon le principe de la figure 9. Dans ce cas, le changement de sens de cintrage nécessité des mouvements complexes.

This situation therefore imposes, when the need for two bending directions is necessary, to consider a modular design with several parts, each of which has only one direction of bending, or the use of heavier solutions and / or more complex, so the state of the art offers several solutions namely:

• realize the two directions of bending with an equipment having two bending heads whose principle is represented at the figure 6 . The tube is successively bent in a first direction by a first head (a) of bending and then in opposite directions by passing through a second bending head (b).
• realize the two directions of bending with equipment comprising two tools (c, d) mounted on either side of a bending head, and whose principle is represented in figure 7 . The two tools (c, d) are mounted on the same axis (e) of bending, the change of bending direction requires a complex combination of movements.
• realize the two directions of bending with two tools (f, g) with switchable axes of rotation according to the principle of the figure 8 . In this case, the switching of the direction of bending is very fast, but the mechanics are complex. In addition, this solution does not allow a change of bending radius.
• realize the two directions of bending with two tools (h, i) located on different planes according to the principle of figure 9 . In this case, the change of direction of bending requires complex movements.

All these solutions of the prior art involve a more or less complex mechanics and both require bending tools.

Therefore, for the most buoyant markets such as automotive and aerospace, always looking for economic solutions and adapted to simple and fast changes in series, the need of designers is not fully satisfied.

The objective of the present invention is to provide a more economical solution than those of the prior art and which meets the needs of designers.

The invention achieves this objective and consists of a bending head according to claim 1.

The invention also relates to a machine equipped with a bending head of this type, controlled by a numerical control managing all the movements of the components of the machine, according to claim 2.

More particularly, the numerical control calculates the movements of the components and the bending parameters from the two planar coordinates (x and y) and the rotation angle (α) defining the movements of the jaw.

The numerical control further conventionally controls a guide-ruler means, a tube positioning means, a mandrel guiding means and a tube positioning means.

Finally, the machine has a symmetrical structure whose bending direction changes are made by simple rotation of the axes.

• figures 1 et 2 : schémas de principe d'un ensemble de cintrage par enroulement-tension,
• figure 3 : exemple de tube cintré par un ensemble des figures 1 ou 2,
• figures 4 et 5 : schémas de principe de cintrage en sens-horaire, ou anti-horaire,
• figure 6 : schéma d'un équipement à deux têtes pour cintrage dans les deux sens,
• figure 7 : schéma d'un équipement à deux outils symétriques,
• figure 8 : schéma d'un équipement à deux outils commutables,
• figure 9 : schéma d'un équipement à deux outils dans des plans différents,
• figure 10 : schéma de principe d'une tête de cintrage symétrique selon l'invention,
• figure 11 : schéma montrant les trois mouvements de rotation principaux,
• figure 12 : détail des positions des éléments constitutifs de la tête en position de départ,
• figure 13 : détail des positions en phase de bridage du tube,
• figure 14 : détail des positions en phase de cintrage du tube,
• figures 15, 16, 17 : détail des positions pour un cintrage en sens contraire de celui obtenu avec les figures 12, 13,14,
• figures 18, 19 : détail des positions lorsque le mors est ouvert puis fermé,
• figure 20 : représentation graphique des efforts
• figures 21, 22 : schémas d'une machine complète et des mouvements de ses différents composants.

The invention will be better understood from the following description given with reference to the following appended figures:

• Figures 1 and 2 : schematic diagrams of a winding-voltage bending assembly,
• figure 3 : example of tube bent by a set of Figures 1 or 2 ,
• Figures 4 and 5 : diagrams of principle of bending in clockwise, or counter-clockwise,
• figure 6 : diagram of two-headed equipment for bending in both directions,
• figure 7 : diagram of equipment with two symmetrical tools,
• figure 8 : diagram of a device with two switchable tools,
• figure 9 : diagram of equipment with two tools in different planes,
• figure 10 : schematic diagram of a symmetrical bending head according to the invention,
• figure 11 : diagram showing the three main rotational movements,
• figure 12 : detail of the positions of the constituent elements of the head in the starting position,
• figure 13 : detail of the positions in the phase of clamping the tube,
• figure 14 : detail of the positions in phase of bending of the tube,
• Figures 15, 16, 17 : detail of positions for bending in the opposite direction to that obtained with the Figures 12, 13,14 ,
• Figures 18, 19 : detail of the positions when the jaw is opened then closed,
• figure 20 : graphic representation of the efforts
• Figures 21, 22 : diagrams of a complete machine and movements of its various components.

The inventive idea was to develop a new architecture replacing the current bending arm and that would allow the bending of thin-walled tubes in both directions (clockwise and anti-clockwise) with the same tooling.

This new architecture must therefore include a symmetrical bending means.

• le bras de cintrage est remplacé par une couronne, d'où une structure symétrique de la rotation,
• la rigidité est nettement meilleure car le diamètre de guidage est beaucoup plus important qu'avec un bras de cintrage,
• le déplacement (serrage) du mors en translation est obtenu par trois rotations contrôlées par des axes numériques,
• le déplacement linéaire du mors de serrage se fait en interpolant ces trois axes.

On the basis of this idea of symmetry, the inventive idea evolved towards the concept of a circular bending head whose characteristics are represented on the Figures 10 to 17 and which are the following:

• the bending arm is replaced by a ring, hence a symmetrical structure of the rotation,
• the rigidity is much better because the guide diameter is much larger than with a bending arm,
• the displacement (clamping) of the jaw in translation is obtained by three rotations controlled by numerical axes,
• the linear displacement of the clamping jaw is done by interpolating these three axes.

The clamping system behaves like a connecting rod from where a fast movement during the race, where the efforts are weak, and slower at the end of the race, where the efforts are important because of the triangulation of the axes.

In addition, the fact of using three synchronized rotations makes it possible to program the position of the jaw along two perpendicular axes and a rotation.

Controlling the orientation of the clamping jaw by rotation optimizes clamping.

The operation of this bending head will be better understood with the aid of the following detailed description.

The circular bending head (1) (see figure 10 and 11 ) has a circular main plate (2) rotating about its central axis (A ₁ ). The bending tools are composed of a forming roller (3) concentrically mounted on the axis (A ₁ ) and above the main plate (2), a relatively straight flattening jaw (4). the axis (A ₃ ) in a reference (Ox, Oy).

This rectilinear movement results from mounting the bit according to a principle of the eccentric.

The jaw (4) is rotatably mounted about an axis (A ₃ ) mounted itself on the periphery of a satellite plate (5) rotatably mounted on an axis (A ₂ ) carried by the main plate and at a predetermined distance from the axis (A ₁ ).

A slider (6) is provided to guide the tube conventionally.

On the schematic diagram of the figure 11 the bending head is composed of a main plate (1) rotating around the central axis (A ₁ ). A second rotation (A ₂ ) integral with the first rotation, eccentric with respect to the axis (A ₁ ) makes it possible to move an eccentric point of the axis (A ₂ ) relative to the axis of the first rotation (A ₁ ). This displacement in a plane perpendicular (PL ₁ ) to the central axis (A ₁ ) allows a relative displacement of the point (PT ₁ ) with respect to the point (PT ₂ ). The association and / or the combined displacement of these two axes makes it possible to generate any trajectories in the plane (PL ₁ ). This defines the origin of a vector. The direction of the vector essential for the operation of a bending tool is provided by the third rotation (A ₃ ) which allows to orient the vector in the coordinate system defined along the axis (A ₁ ).

There is therefore a system allowing the vector to move in any way in the plane (PL ₁ ).

This mechanical principle is applicable to move a vector in a plane.

This displacement is decomposed for the bending of the tubes in a linear displacement phase to tighten the tube on the bending form, another phase of circular displacement for the bending of the tube, a linear displacement phase for the loosening of the tube.

The following is described with reference to Figures 12 to 14 the bending phases in one direction and with reference to Figures 15 to 17 the bending phases in the opposite direction.

The figure 12 corresponds to a loading phase of a tube (6): the forming roller (3) and the strip (7) being aligned, the clamping jaw (4) is spaced apart to allow the tube (6) to be loaded by the before, and is in a starting position (P ₁ ) located at a distance (S) from the axis (A ₁ X) of the machine.

The figure 13 corresponds to a clamping phase of the tube: the roller 3 does not move, the strip comes into contact with the tube (6), and the conjugation and synchronization of the rotations of the main plate (2) anti-clockwise around ( A ₁ ), the satellite tray (5) in the clockwise direction around (A ₂ ) and the jaw (4) anti-clockwise around (A ₃ ) generates a rectilinear movement of the jaw which clamps the tube ( 6) against the forming roller.

This configuration of the jaw (3) on an eccentric axis on the satellite tray allows to obtain very large clamping forces.

The figure 14 corresponds to the phase of bending of the tube: the tube (6), clamped on the roller (3) by the jaw (4), is wound on the roller (3) by rotation of the roller in the clockwise direction about the axis (A ₁ ) and by rotating the satellite plate clockwise about the same axis (A ₁ ), the jaw pivoting around (A ₃ ) to remain constantly in the optimum clamping position.

The unclamping phase is not shown, in this phase, the roller remains fixed, a reverse synchronization of the rotations used in the clamping phase allows the clamping jaws to move away from the forming roller. When the jaw is removed, the slide (7) moves back and forth, the main plate (2) returns to position for the next hanger, the tube advances and the forming roller returns to position. A new phase of clamping can begin.

The Figures 15, 16, 17 represent the same phases of operation from a ruler and a satellite tray positioned symmetrically on the figure 15 relative to their starting positions of the figure 12 . The figure 15 therefore represents a loading phase, the figure 16 a bridging phase, and the figure 17 a bending phase in the opposite direction of the bending obtained with the phases of Figures 12 to 14 . The point (P ₂ ) marks the starting position of the bit which is located at a distance (S ') from the axis (A ₁ X) of the machine, and symmetrically with respect to the starting position (P ₁ ).

• en figure 18, la position des axes lorsque le mors est ouvert, (S) indiquant le réglage initial de serrage,
• en figure 19, la position des axes lorsque le mors est fermé, les cotes (x) et (y) indiquant le réglage final de serrage,
• en figure 20, la triangulation des efforts en position fermée du mors avec (Fa) pour la composante de serrage sur un axe et (Fc) pour la composante de serrage sur le tube, et (α) l'angle de rotation du mors, Tg (composante) qui montre que pour un effort (Fa) donné, lorsque l'angle alpha tend vers O, l'effort de serrage sur le tube (Ft) croit très fortement (tend vers l'infini donc limité par la rigidité de l'ensemble).

The Figures 18, 19, 20 , schematically represent the rotations (AXE1) around the axis (A ₁ ), (AXE2) around the axis (A ₂ ), and (AXE3) around the axis (A ₃ ) for bending in a clockwise direction , and show respectively:

• in figure 18 , the position of the axes when the jaw is open, (S) indicating the initial tightening setting,
• in figure 19 , the position of the axes when the jaw is closed, the dimensions (x) and (y) indicating the final tightening setting,
• in figure 20 , the triangulation of the forces in the closed position of the jaw with ( fa ) for the clamping component on an axis and ( Fc ) for the clamping component on the tube, and (α) the angle of rotation of the jaw, Tg (component) which shows that for an effort ( fa ) given, when the angle alpha tends towards O, the clamping force on the tube ( ft ) believes very strongly (tends towards infinity, therefore limited by the rigidity of the whole).

The fact of using three synchronized rotations makes it possible to program the rectilinear movement of the jaw in two perpendicular directions (Ox) and (Oy) and according to its angle rotation (α), which corresponds to the necessary rotation of the jaw around its axis. (A ₃ ) so that it always remains optimally positioned relative to the roller and thus optimize the tightening of the tube during the rotation of said roller (3).

In the case of bending tubes or profiles described below for example, all the functions and movements necessary to constitute a complete optimal machine incorporating a bending head according to the invention, is detailed below in connection with the Figures 21, 22 .

• moyen (9) de guidage-réglette par exemple : pour le serrage et l'accompagnement du tube ou profilé,
• moyen ou chariot (8) de positionnement du tube : pour le serrage, l'avance et l'orientation du tube,
• moyen de guidage (10) : pour la mise en position du mandrin (11) dans le tube avant cintrage puis son retrait après cintrage,
• moyen de positionnement du tube : pour son positionnement à droite ou à gauche et le retournement de la tête de serrage pour la mettre en position symétrique.

The necessary means are:

• means (9) guide-rule for example: for clamping and accompanying the tube or profile,
• means or carriage (8) for positioning the tube: for clamping, advancing and orienting the tube,
• guiding means (10): for positioning the mandrel (11) in the tube before bending and then removing it after bending,
• means for positioning the tube: for positioning it to the right or to the left and reversing the clamping head to put it in a symmetrical position.

• AXE 1 : Rotation pour cintrage du tube,
• AXE 2 : Rotation pour serrage mors (4),
• AXE 3 : Rotation pour orientation mors (4),
• MVT 4 : Rotation du galet formeur (3),
• MVT 5 : Serrage réglette (7) en translation,
• MVT 6 : Avance réglette (7) en translation,
• MVT 7 : Déplacement linéaire d'un chariot porte tube (8),
• MVT 8 : Rotation pour orientation du chariot (8) pour un cintrage dans un autre plan,
• MVT 9 : Serrage tube.
• MVT 10 : Avance et retrait de mandrin (11)
• MVT 11 : Rayon de cintrage chariot (8),

A control by numerical control allows the simultaneous and synchronized rotation of the three main axes but also the complementary movements necessary, namely:

• AXIS 1: Rotation for tube bending,
• AXIS 2: Rotation for clamping jaws (4),
• AXIS 3: Rotation for jaw orientation (4),
• MVT 4: Rotation of forming roller (3),
• MVT 5: Tightening slide (7) in translation,
• MVT 6: Advance slider (7) in translation,
• MVT 7: Linear displacement of a tube carrier (8),
• MVT 8: Rotation for carriage orientation (8) for bending in another plane,
• MVT 9: Tightening tube.
• MVT 10: Chuck feed and withdrawal (11)
• MVT 11: Cart bending radius (8),

It is specified that, in the example shown, all the rotational movements are plane and horizontal, the axes of rotation being vertical and that the guide of the mandrel is classically horizontal, in the axis of the tube from an erasure position or reversing the figure 21 , according to which it is removed from the tube (not visible on the figure 21 ) and to a working position in which it is introduced inside the tube to prevent crushing during bending.

Other configurations could be provided without departing from the scope of the invention, for example a configuration where the bending head would be vertical with rotational movements in a vertical plane.

One could also provide to place the roller (3) and the other satellite elements of the eccentric below the main plate (2).

A machine according to the invention preferably has a bending capacity of tubes 40 to 80 mm in diameter with a maximum thickness of 2 mm for a diameter of 80 mm.

Claims (5)

1. Bending head, for example for a rotary draw bending technique, of the type comprising a bending-clamp assembly set in rotation about an axis (A₁), one or more rollers holding a tube or profile (6) clamped against the bending form during the bending process and a single bending-clamp assembly able to be positioned according to one or other of two bending starting positions (P₁) and (P₂), which are symmetrical in relation to the axis of the tube so as to allow either bending from (P₁) in one bending direction or bending from (P₂) in an inverse direction, characterised in that the single assembly is a bending head (1) formed by a main plate (2) turning about a first central axis (A₁), a roller (3) mounted concentrically on said first axis (A₁) and parallel to the main plate (2), from a clamping clamp (4) mounted in rotation about a third axis (A₃) mounted eccentrically on a satellite plate (5) mounted in rotation on a second axis (A₂) supported by the main plate and at a predetermined distance from the first axis (A₁).
2. Bending machine, for example for a rotary draw bending technique, of the type comprising a bending-clamp forming assembly set in rotation about an axis (A₁), one or more rollers holding a tube or profile (6) clamped against the bending form during the bending process, characterised in that it comprises a bending head according to claim 1 and a numerical control managing all of the movements of the machine components.
3. Bending machine according to claim 2, characterised in that the numerical control calculates the movements of the components and the bending parameters from two planar coordinates (x and y) and the angle of rotation
   (α) defining the movements of the clamp (3).
4. Bending machine according to claim 2, characterised in that the numerical control also controls, in a conventional way, a guide-strip means (9), a tube-positioning means (8), a mandrel guide means (10) and a tube-positioning means.
5. Bending machine according to one of claims 2 to 4, characterised in that it has a symmetrical structure, wherein changes in the direction of bending are performed by simple rotation of the axes (A₁, A₂, A₃).

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