EP0077700B1 - Method for the local deforming of round tubes into tubes with flat sides, and die for doing the same - Google Patents

Description

Tubes used in industry generally have a circular section because of the ease of their continuous production, from strip rolls, on a tube machine and also because of their mechanical qualities. However, this circular shape poses problems when one wants to perform certain operations such as drilling a tube, welding it with other parts, docking it with other tubes, and in particular assembling several similar tubes of so as to allow them to lead into another tube of larger section.

The object of the present invention is to remedy these drawbacks by making it possible to form local flat surfaces on the tube.

The subject of this invention is, in a first aspect, a method of local deformation of a round tube into a tube comprising in the deformed zone two flat faces which consists in axially introducing into the tube an elongated punch comprising a dihedron between two guide faces, placing the portion of tube to be deformed, containing the punch, opposite the side walls of a V-groove formed either by a die, or by the punches of two adjacent tubes to be deformed simultaneously, then to be applied to the external free surface of the tube a compression part, also provided with a groove, and tightening it until it comes into contact with the die respectively the two punches and until the penetration of the tube and the punch in the bottom of the V-groove, so that the tube portion follows the contour of the cavity delimited by the V-groove and that of the compression part this, a charity having a triangular section; finally we move aside the compression part and the matrix and we withdraw the punch from the tube.

The tube thus produced has, over a portion of its length only, a substantially triangular section, but only its shape has been modified so that its mechanical qualities have not been altered but that on the other hand its adaptation to be fixed or docked at other parts is significantly improved.

The invention also extends to a forming tool or punch, intended for the implementation of this method, which comprises a dihedral with a determined angle between two narrow guide and centering faces, the edges of the dihedron and of the ends of the two lateral faces being generators of the same cylinder.

According to a preferred embodiment, the tool comprises, opposite the edge of the dihedron, a curved surface whose axis coincides with this edge.

The cylinder on which the edges of the tool are placed having a diameter very slightly smaller than that of the tube to be deformed, the tool can easily be inserted inside this tube to the desired point, and even removed from it. tube after its deformation. It is also always perfectly centered in the tube and can easily be centered in relation to the matrix.

The description below will moreover highlight the advantages and characteristics of the invention.

• - la fig. 1 est une vue en perspective montrant l'accostage de plusieurs tubes déformés selon le procédé de l'invention;
• - la fig. 2 est une vue en bout, à échelle légèrement agrandie, des tubes de la fig. 1;
• - la fig. 3 est une vue analogue à la fig. 2, d'une autre application de l'invention;
• - les fig. 4 et 5 illustrent deux phases du procédé de déformation du tube, respectivement avant et après la compression de ce dernier;
• - la fig. 6 est une vue en perspective d'un poinçon de formage selon l'invention;
• - la fig. 7 est ne vue en perspective d'un autre exemple de réalisation d'un tube déformé localement par le procédé de l'invention.

In the accompanying drawings:

• - fig. 1 is a perspective view showing the docking of several deformed tubes according to the method of the invention;
• - fig. 2 is an end view, on a slightly enlarged scale, of the tubes of FIG. 1;
• - fig. 3 is a view similar to FIG. 2, of another application of the invention;
• - figs. 4 and 5 illustrate two phases of the tube deformation process, respectively before and after the compression of the latter;
• - fig. 6 is a perspective view of a forming punch according to the invention;
• - fig. 7 is only a perspective view of another embodiment of a locally deformed tube by the method of the invention.

Figs. 1 and 2 illustrate a particularly interesting application of the invention. They indeed show three tubes of circular section, 1, 2 and 3, which are arranged parallel side by side in the extension of a tube 4 of larger diameter. Each of the tubes 1, 2 and 3 is deformed at its end close to the tube 4 so as to have two flat faces, respectively 6, 7, 8, 9, and 10, 11, capable of being approached each against the corresponding face of one of the other two tubes. The two flat faces 6, 7 are joined by a curved surface in a portion of a circle 12, the diameter of which is greater than that of the initial tube 1, 2 or 3, each of the surfaces 12 forming a third of a circle, so that the assembly of the three deformed tubes 1, 2 and 3 is delimited externally by a circumference constituted by the succession of the three surfaces 12, as shown more clearly in FIG. 2.

The outside diameter of the assembly of the three deformed tubes is equal to, or preferably slightly less than, the internal diameter of the tube 4, so that the three tubes 1, 2 and 3 can easily be connected to this tube 4 and lead to the inside.

Of course a connection can be made in a similar manner when the tubes of circular section are more than three in number, for example four in number, as shown in FIG. 3. In this case only the angle which the plane faces 13 and 14 form between them, as well as the value of the arc of the corresponding curved surface 16, are 90 ° instead of 120 °.

Whatever the value of the dihedral angle that the flat faces of the circular section tube must form, the deformation is obtained by means of a forming tool, or punch, such as that shown in FIG. 6. This punch 18 is formed from a solid metal bar, of circular section having a radius close to or very slightly less than the internal radius of the tube to be deformed, for example the tube 1 of FIG. 4. This punch 18 has two flat faces, respectively 20 and 22, intersecting on an edge 23 and thus forming a dihedral whose angle corresponds to that which one wants to obtain on the tube 1. Each of the flat faces 20 and 22 joins a cylinder portion 24, 26 respectively of the initial bar and the edge 23 of the dihedral formed by the faces 20 and 22 is practically on a generatrix of the cylinder of the external surface of this bar. Consequently, the edges 27, 28 and 29, 30 of the lateral faces 24 and 26, and the edge 23 of the dihedral constitute the generatrices of the same cylinder.

Furthermore, opposite the apex 23 of the dihedral, the lateral faces 24 and 26 are connected by a surface 32, also curved, but having its axis coincident with the edge 23.

The punch 18 can receive any desired length but its cross section remains inscribed in a circle of diameter at most equal to the internal diameter of the tube. This punch 18 can thus easily be introduced into the end of a tube which must be deformed, for example at the left end of the tubes shown in FIG. 1. The lateral faces 24 and 26 then play the role of guiding and centering members.

The portion of tube containing the punch 18 is then placed in a V-shaped groove, 34, formed at the top of a matrix 36, the dihedron 20, 22, 23 of the punch being exactly centered relative to the groove 34, while that the tube 1 is in tangential support on the two inclined walls of the groove but protrudes outside of the latter (fig. 4).

A compression part 38, also comprising a groove 40, is then lowered on the tube 1, then clamped on this tube which it presses into the groove 34 until it itself comes to bear against the matrix 36. During this movement of the part 38 the bottom of the groove 40 pushes the upper part of the tube 1 against the curved surface 32 of the punch 18, then pushes this punch itself into the groove 34 by deforming the lower part of the tube 1 , which is applied against the two flat faces 20 and 22 of the punch 18.

When the part 38 comes into contact with the matrix 36 the groove 40 closes the groove 34 and delimits with it a cavity whose cross section has substantially the shape of a triangle. Preferably, as the drawings show, the groove 40 has a curved shape, its radius of curvature being very close to that of the upper cylindrical surface 32 of the punch, so that the tube 1 deformed by compression takes, as shown fig. 5, also a cross section in the shape of a triangle having a curved rib. At this time, in fact, the tube 1 practically follows the shape of the cavity delimited by the grooves 40 and 34 and, moreover, is supported on the punch 18.

However, as shown in particular in fig. 5, the side faces 24 and 26 at the end of compression are free, so that the punch 18 can slide inside the tube 1, even after the latter has been deformed. Consequently, after the compression piece 38 and the die 36 have moved away, the punch 18 is withdrawn from the tube 1 which is ready to be used, that is to say possibly to be assembled with other tubes identical, as shown in figs. 1 to 3.

Preferably, as shown in fig. 6, the punch 18 is connected, by a transition portion 41, to a manipulation handle 42. The active part of the forming tool or punch 18 can be relatively short, as shown in FIG. 6, or have a very much greater length and thus allow the deformation of a part of the tube relatively distant from its open end.

For example, as in the embodiment shown in FIG. 7, a punch 18 of great length can be introduced into a tube 44, of circular section, and reach a central part 46. The portion of tube 46 containing the punch 18 is then placed in the die 36 and compressed by the part 38, as described for the tube 1. In this case, as in the previous one, the axial length of these two members, that is to say of the matrix and of the compression part 38, as well as that of the grooves 34 and 40 which are open at their two ends, correspond to the length of the portion of tube which it is desired to deform. Therefore, in the embodiment of FIG. 7, the length of the grooves 34 and 40 used corresponds to the length of the tube portion 46. Thus only this part is deformed, the rest of the tube 44 retaining its circular section.

Of course, the angle of the dihedral formed by the flat faces 20 and 22 of the portion 46 can vary and be chosen as a function of the particular application for which the tube 44 is intended.

In all cases, only the shape of the section of the tube is modified. The material itself retains its own properties, so that the deformation does not weaken the mechanical strength of the tube but, on the contrary, allows it to be easily fixed and assembled with other tubes or with flat parts or others.

When several tubes are intended to be docked in the manner shown in FIGS. 1 to 3, it is often advantageous to deform them simultaneously. A punch 18 is then introduced into each tube of tubes 1, 2, 3 for example, then these tubes are pressed against each other by compression pieces in the portion of a cylinder which bring them together so that they deform at their reciprocal contact. Each abuts in the V-groove formed by the punches of two adjacent tubes and follows the shape of the punch it contains.

No abnormal deformation appears, because the pressure is distributed evenly over all the tubes and the punches are tightened until practically coming into contact with each other. On the other hand, the removal of the punches remains easy.

It is therefore possible to simultaneously deform already installed tubes, when their assembly, for example on another tube of larger diameter, which considerably facilitates assemblies of this type.

Claims (14)

1. A method for locally deforming a round tubo into a tube comprising two planar surfaces in the deformed region characterised in that it comprises axially inserting in the tube an elongated punch (18) comprising a dihedron (20, 22) between two lateral guiding surfaces (24, 26), placing the portion of the tube to be formed, in facing relation to inclined lateral walls of a V-shaped groove (34) formed by a die (36), or by the punches of two adjacent tubes to be deformed simultaneously, then applying on the outer free surface of the tube (1) a compression member (38) which is also provided with a groove, and urging the compression member until it contacts the die, respectively the two punches, and the tube and punch have penetrated the inner end of the V-shaped groove, so that the tube conforms to the contour of the cavity defined by V-shaped groove and that of the compression member, this cavity having a triangular section; then separating the compression member and the die, and withdrawing the punch from the tube.

2. A method according to claim 1, characterised in that it comprises pressing the tube containing the punch by means of a compression member whose groove is curved, with a radius of curvature close to the radius of curvature of the upper surface of the punch, and an axis which substantially coincides at the end of the compression with the inner end of the V-shaped groove (34) of the die.

3. A method according to claim 1 or 2, characterised in that the grooves (34, 40) of the die and compression member have a width exceeding the diameter of the tube (1) to be deformed.

4. A method according to claim 1, 2 or 3, characterised in that the axial dimension of the die and of the compression member (36, 38) corresponds to the length of the desired planer surfaces of the tube.

5. A method according to any one of the claims 1 to 4, characterised in that it comprises inserting the punch (18) in the end of the tube (1, 2, 3) to be deformed and then placing this end between the die and the compression member.

6. A method according to any one of the claims 1 to 4, characterised in that it comprises inserting a punch (18) of relatively great length until an intermediate part of the tube is reached, and placing this intermediate part (46) in the V-shaped groove (34) of the die.

7. A forming punch for locally deforming a tube of circular section, characterised in that it comprises a dihedron (20, 22, 23) having a given angle between two narrow guiding and centering surfaces (24, 26), the edge (23) of the dihedron and the edges (27, 28-29, 30) of the end of the two lateral surfaces being generatrices of a common cylinder.

8. A punch according to claim 7, characterised in that it comprises, opposed to the apex edge of the dihedron (23), a curvced surface (32) whose axis coincides with this edge.

9. A punch according to claim 7 or 8, characterised in that the lateral guiding and centering surfaces are formed by portions of a cylinder whose diameter is slightly less than that of the tube to be deformed and from which the punch is cut.

10. A punch according to any one of the claims 7 to 9, characterised in that the angle of the dihedron is at the most equal to 120° .

11. A tube of circular section, characterised in that it comprises on a part of the length thereof two planar surfaces and a substantially triangular section.

12. A tube according to claim 11, characterised in that the part of triangular section is located at one of its two ends.

13. A tube according to claim 11, characterised in that the part (46) of triangular section is located at an intermediate point of its length.

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