EP1430968B1 - Forming tool and method to produce a deformed end of a tube - Google Patents

Description

The invention relates according to the preambles of claims 1 and 6, a mold, or a corresponding method for producing a deformed end of a tube, wherein with the deformed end, a connecting piece and a union nut a pipe connection can be produced, wherein the mold at least two clamping jaws for fixing a tube on the outer lateral surface and a compression body, in which the reshaped end of the tube is used before the forming process and has a bottom and a projecting in the axial direction and the tube enclosing collar, wherein during the forming process on the bottom of the compression body in the axial direction, a force in the associated end face of the tube can be introduced and thereby the end of the tube is radially outwardly deformable (see, for example, de 100 40 596 C).

DE 195 11063 A1 discloses a pipe joint which comprises a connecting piece with a conical bore, a nut with a conical surface and a pipe with an integrally formed end portion. The end portion has clamping surfaces produced by compression, which have an orientation as the associated conical bore in the connection piece or the conical surface in the union nut. In the manufacture of the end portion, the tube is subjected to deformation with a certain upsetting path. In DE 195 11 063 A1, the deformed end portion of the tube is either shaped so that it has an axially parallel end piece, which is upstream of the tapered portion or does not have such an axially parallel end piece and starting from the end face of the tube directly a tapered clamping surface followed.

A suitable for producing such an end molding tool, which is also disclosed in DE 195 11063 A1, either has a compression body in a cup shape with a flat bottom part or is additionally provided with an inner dome or support pin which penetrates into the interior of the end portion to be formed. The last-mentioned variant can be used only with restrictions, in particular, if pipes with the same outside diameter, but with different wall thicknesses, i.e. with the same molding tool, are used. also different in the inner diameter, to be reshaped.

Furthermore, from DE 195 20 099 A1 yet another pipe connection and a method for their preparation known. The deformed tube has in this case only a tapered clamping surface, which cooperates with the corresponding conical surface in the union nut. In the area of the connecting piece, the deformed Pipe on an axially parallel end portion. In a chamber which is bounded by the inner cone of the connecting piece in the axially parallel end piece of the tube and a radial clamping surface adjacent thereto, a soft seal is arranged, which is compressed in the operating state of the pipe joint therein.

A mold shown in DE 195 20 099 A1 has a pot-shaped compression body with a cylindrical interior into which the end section of the pipe to be formed is inserted. The inner diameter of a collar of the compression body is adapted to the outer diameter of the tube to be formed.

In addition, from DE 101 08 309 C1 discloses a further pipe connection with a formed tube, in which the formed tube has no axially parallel cylindrical end portion. In this case, a seal is arranged between the end face of the deformed tube and an opposite end face of the Verschraubungskörpers, which consists at least partially of a deformable plastic material. In this case, in order to achieve a reliable seal, the plastic material is pressed in compression in an opposite direction to the direction of movement of the tube in its compression in a chamber of the inner cone of the Verschraubungskörpers, one to the first tapered clamping surface of the deformed Pipe adjacent sealing surface and an end face of the metallic material existing part of the seal is limited.

If the deformed end of the pipe according to DE 101 08 309 C1 is produced with the aid of a molding tool, as disclosed in principle, for example, in the aforementioned DE 195 11 063 A1, irregularities in the shaping occur, in particular in the case of pipes with a small diameter and small wall thickness Area of the front conical surface on. These irregularities are manifested in particular in the form of waves, which make a flat contact of the conical clamping surface on the associated inner cone of the connecting piece impossible and therefore can make the tightness and strength of the pipe joint in total question. Also occur due to the lack of large-scale plant increased settling phenomena at a dynamic load on the pipe connection, which in turn lead to a relaxation and potential leakage.

Furthermore, DE-OS 21 10 758 discloses a method for producing a coupling sleeve. The coupling sleeve thus obtained serves for lack of a thread on the sleeve itself or on the tube ends to be inserted therein not to produce a pipe connection using a union nut. Rather, the tube end is held by means of two clamping jaws acting on its outer lateral surface. Subsequently, a mandrel is inserted into the pipe end, thereby less a force in the axial direction but rather in the radial direction is introduced, since the pipe is expanded by the force acting on the inner shell surface forces to the outside. In contrast to the method described above, a mandrel with oversize is used in this procedure, the jaws themselves serve as a cup-shaped form element. The mandrel has at its axial end an annular groove with a conically outwardly extending groove base which causes the end face of the tube is deformed against the upsetting direction in the tapered groove bottom, in particular in the region of the inner peripheral edge of the end face, whereas the outer Circumferential edge for initiating the compression force is used.

Finally, DE 100 40 596 C1 and JP 2002 001 462 A describe two devices for reshaping a workpiece end region and the associated methods. In both devices, with a compression body with a longitudinal axis of the tube to be formed radially, i. worked perpendicular to the longitudinal axis, extending bottom surface. In particular, in the case of small pipe diameters, irregularities can therefore occur when forming a conical clamping surface, as shown in particular in JP 2002 001 462 A, which can lead to subsequent leaks in the pipe connection to be produced.

The invention has for its object to provide a mold for producing a deformed end of a tube and a related method, with the In all the usual combinations of pipe outside diameters and wall thicknesses irregularities in the shape of the front, in particular conical clamping surface can be avoided.

Starting from a mold of the type described above, this object is achieved in that the bottom of the compression body is shaped so that in the state of contact between the bottom and the end face of the tube but before the forming process between the end face of the tube and the bottom of the outer circumferential edge of the end face seen from a space is available.

Such a clearance makes it possible for material to flow back in the outer region of the pipe wall against the compression direction during the forming process. Such reflux is particularly advantageous when the end portion of the tube to be reshaped is to be displaced outwardly conically or similarly shaped directly from the end face or at least not far away from it. In the case of a flat bottom in the region of the entire end face of the formed tube - as is known from DE 195 11063 A1 - it comes in the region of the outer circumferential surface of the conical portion of the tube tends to the above-described Aufwerfungen, as in contrast to the range in near the inner peripheral edge of the face in the outdoor area tends to be a material compression takes place. Such a compression is very effectively avoided by the free space proposed by the invention, whereby the quality of the deformed end portions, which are made with the mold according to the invention, is particularly high quality.

The advantages of the molding tool according to the invention come into play, in particular, when the inner diameter of the collar increases continuously away from the ground, and in particular when the inner circumferential surface of the collar is conically shaped in an area adjoining the floor. Incidentally, such a shape of a reshaped tube is particularly well suited to correspond with a standardized 24 ° cone in a receiving socket.

The invention further ausgestaltend is provided that the clamping jaws have a compression body facing portion in which the inner circumferential surface has a diameter which is greater than the outer diameter of the tube to be formed. In this way, the dividing plane between the compression body and the clamping jaws can be arranged in the region of the largest diameter of the formed tube.

In this context, it is further preferable that the transition from the collar of the compression body to the clamping jaws in the area of the inner circumferential surfaces of the aforementioned parts is continuous and has no kink.

• a) Einspannen des Rohres mittels mindestens zwei an dessen äußerer Mantelfläche angreifender Spannbacken,
• b) Einleiten einer in axiale Richtung des Rohres wirkenden Kraft in eine Stirnfläche des Rohres mittels eines Stauchkörpers,
• c) Stauchen des Endes des Rohres, wodurch die äußere Mantelfläche in einem an die Stirnfläche angrenzenden Bereich radial nach außen geformt wird.

The object according to the invention is furthermore achieved by a method for producing a deformed end of a tube, wherein a tube connection can be produced with the deformed end, a connection piece and a union nut and the method comprises the following steps:

• a) clamping the tube by means of at least two clamping jaws acting on its outer circumferential surface,
• b) introducing a force acting in the axial direction of the tube in an end face of the tube by means of a compression body,
• c) compressing the end of the tube, whereby the outer circumferential surface is formed in a region adjacent to the end face radially outward.

In such a method, at least an outer portion of the end face of the tube is deformed against the upsetting direction of the compression body. According to the method of the invention, it is provided that the end face of the tube is deformed, starting from its outer peripheral edge, against the upsetting direction. A backflow of the tube in this region adjoining the peripheral edge is required, in particular, when a conical surface, in particular a clamping surface with a sealing function, adjoins the formed tube directly at its end face. As a result, irregularities in the shape of the outer jacket of the pipe, in particular undulating jolts, which can impair the tightness and cause undesirable settling phenomena, can be avoided in a very simple manner.

Finally, it is also envisaged that the pipe end will be deformed radially outwards also in the area of the clamping jaws. Such a procedure makes it possible to place the dividing plane between the upsetting body and clamping jaws in the region of the formed tube in which the outer diameter is maximum.

Figur 1

einen Halbschnitt durch ein aus Stauchkörper und Spannbacke bestehendes Formwerkzeug sowie einen Endabschnitt eines Rohres im gefügten Zustand

Figur 2a

einen vergrößerten Ausschnitt aus Figur 1 im Bereich der Stirnfläche des Rohres

Figuren 2b bis 2c

wie Figur 2a, jedoch mit alternativen Konturen des Bodens des Stauchkörpers

Figur 3

wie Figur 1, jedoch im umgeformten Zustand des Rohres und

Figuren 4a bis 4c

eine vergrößerte Darstellung von Ausschnitten des umgeformten Rohrendes unter Verwendung der in den Figuren 2a bis 2c gezeigten Bodenkonturen

The invention will be explained in more detail with reference to several embodiments of molds, which are illustrated in the drawing. It shows:

FIG. 1

a half-section through an existing of compression body and jaw mold and an end portion of a pipe in the joined state

FIG. 2a

an enlarged section of Figure 1 in the region of the end face of the tube

FIGS. 2b to 2c

as Figure 2a, but with alternative contours of the bottom of the compression body

FIG. 3

as Figure 1, but in the deformed state of the pipe and

FIGS. 4a to 4c

an enlarged view of sections of the deformed pipe end using the bottom contours shown in Figures 2a to 2c

Figure 1 shows in half section an end portion of a cylindrical tube 1, which was used with a front portion 2 in a cup-shaped compression body 3. The compression body 3, together with two half-shell-shaped radially movable clamping jaws 4, a mold for forming processing of the end portion of the tube 1. compression body 3 and clamping jaws 4 are together understood as a molding tool in the sense of this patent application. It is according to the invention in principle but also possible that the formation takes place solely in the compression body and the fixation of the pipe takes place in other ways than by clamping jaws.

Figure 2a illustrates that the tube 1 is inserted so far into the compression body 3, that it abuts with the inner circumferential edge 6 of its end face 5 to the bottom 7. The contact between. Tube 1 and bottom 7 take place approximately at one point, in which the contour of the bottom 7 has a kink: While the central region 8 of the bottom 7 is oriented perpendicular to the longitudinal axis 9 of the tube 1, a region 10 adjoins it radially outwards inclined so inclined that between the end face 5 and the bottom 7, a free space 11 remains. This free space 11 is wedge-shaped in cross section with a rounded end, in which the area 10 of the bottom 7 in the inner circumferential surface 12 of a collar 13 of the compression body 3 passes, wherein the collar 13 surrounds the inserted portion 2 of the tube 1.

Starting from the joined position shown in FIG. 1, the upsetting body 3 and the clamping jaws 4 are moved relative to one another in the direction of the arrows 14 around the path 15 (as a rule the upsetting body moves onto the stationary tube), the wall 16 of the tube 1 being radial is deformed outwards.

In Figure 3 is shown in a mirrored half-section of the final state with completely deformed tube 1, wherein associated end faces of the clamping jaws 4 and the compression body 3 in the plane 17 directly abut each other. In this state, the deformed tube 1 has adapted completely to the inner contour of the collar 13, but also to an inner contour 18 of the clamping jaws 4. The transition between the inner circumferential surface of the collar 13 and the clamping jaws 4 runs continuously and without kink.

On the other hand, the deformed tube 1 has-as can be seen in particular from FIG. 4a-adjusted with its end face 5 to the associated inclined surface of the base 7. The end face 5 thus no longer extends in the radial direction as before the forming process, but at an angle α of 90 ° to the inner circumferential surface 19 of the tube 1 as was the case before the forming process. The 90 ° angle α is achieved because also the angle β between the bottom 7 in the region 10 and the adjacent inner circumferential surface 12 of the collar 13 is 90 °. The deformation of the tube in the region of the end face can thus be simplified as rotation about the inner peripheral edge 6, which serves as a kind of joint explained. Since this can be dispensed with in the axial direction of the tube to a compression, it is not in the forming process according to the invention to the dreaded in the art wave-like Aufwerfungen in the region of the outer surface of the pipe end. The transition between the region 10 of the bottom 7 and the inner circumferential surface 12 of the collar 13 by means of a rounding, which makes it possible to use the formed tube 1 for a pipe joint according to DE 101 08 309 C1. In the area of the rounding, a soft seal can come into contact with the inner cone of a connecting piece and unfold there a reliable sealing effect due to the defined surface quality.

Figures 2b and 4b show an alternative embodiment of a compression body 3 ', in which a transition 20 between a central region 8' of the bottom 7 'is arranged approximately in the center of the end face 5 of the tube 1. It follows - with identical inclination the adjoining region 10 'of the bottom 7' (the angle enclosed between the end face 5 and the bottom 7 is approximately 12 °) - a smaller, because further outward clearance 11 ', as in the compression body 3 according to Figures 1 and 2a of Case is.

However, FIGS. 2 b and 4 b can also represent the same upsetting body 3 as in FIGS. 2 a and 4 a, in which only one tube 1 is inserted which, although having the same outside diameter approximately doubled wall thickness 21. If the compression body 3, 3 'according to the invention has no inner support pin or mandrel for the tube 1 to be formed, the possibility is created, with one and the same compression body 3, 3' tubes with the same outer diameter, but with different wall thickness 21 reshape, where It has been found that it is not necessary that the free space 11, 11 'at all wall thicknesses over the entire end face 5 of the tube 1 extends. Especially in pipes with greater wall thickness, the dreaded in pipes with smaller wall thickness irregularities no longer occur, so that the creation of a with the wall thickness 21 of the tube 1 in its size increasing free space 11, 11 'is not appropriate.

The advantage of the arrangement shown in Figure 2b further lies in the fact that required for pipes 1 with greater wall thickness 21 larger forming forces can be introduced from the beginning of the forming over a surface in the end face of the tube 1, whereas the force introduction in the arrangement according to 2a initially takes place only linearly in the region of the inner peripheral edge 6.

Finally, FIGS. 2c and 4c show a further embodiment of a compression body 3 "with a bottom 7" with a different contour in the edge region. While the inner lateral surface 12 of the collar 13 continues to extend at an angle of 12 ° to the longitudinal axis of the tube 1 to create a clamping surface for a 24 ° cone of a connecting piece, the region 10 "of the bottom 7" is curved in an S-shape , The end face 5 of the tube 1 comes into abutment against the bottom 7 "in the region of a bead 22 before the actual forming process begins again, again a free space 11" between the end face 5 and the bottom 7 ", this free space 11" being in the region the outer circumferential edge 23 of the tube 1 starts and extends to the contact area at the bead 22. In Figure 4c, the shape of the end portion of the tube 1 is shown after completion of the conversion.

Claims (8)

1. A forming tool for producing a formed end of a pipe (1), with a pipe connection being producible with the formed end, a pipe coupling and a union nut, and with the forming tool having at least two clamping jaws (4) for fixing the pipe (1) on its outer jacket surface and an upsetting body (3, 3', 3") into which the end to be formed of the pipe (1) is insertable prior to the forming process, and which comprises a floor (7, 7', 7") as well as a collar (13) projecting in the axial direction and enclosing the pipe (1), with a force being introducible into the associated face surface (5) of the pipe (1) during the forming process via the floor (7, 7', 7") in the axial direction and the end of the pipe (1) thus being deformable radially to the outside, characterized in that the floor (7, 7', 7") of the upsetting body (3, 3', 3") being shaped in such a way that in the state of contact between the floor (7, 7', 7") and the face surface (5) of the pipe (1), but prior to the forming process, a cavity (11, 11', 11") is present between the face surface (5) of the pipe (1) and the floor (7, 7', 7") as seen from the outer circumferential edge (23) of the face surface (5).
2. A forming tool according to claim 1, characterized in that the inside diameter of the collar (13) increases continually in the direction away from the floor (7, 7', 7").
3. A forming tool according to claim 1 or 2, characterized in that the inner jacket surface (12) of the collar (13) is shaped conically in a region adjacent to the floor (7, 7', 7").
4. A forming tool according to one of the claims 1 to 3, characterized in that the clamping jaws (4) comprise a section facing the upsetting body (3, 3', 3") in which the inner jacket surface (18) has a diameter which is larger than the outside diameter of the pipe (1) to be formed.
5. A forming tool according to one of the claims 1 to 4, characterized in that the transition from the collar (13) of the upsetting body (3, 3', 3") to the clamping jaws (4) is continuous in the region of the inner jacket surfaces (12) of the parts mentioned above.
6. A method for producing a formed end of a pipe (1), with a pipe connection being producible with the formed end, a pipe coupling and a union nut, comprising the following method steps:

   a) clamping of the pipe (1) by means of at least two clamping jaws (4) acting up its outside jacket surface;

   b) introduction of a force acting in the axial direction of a pipe (1) into a face surface (5) of the pipe (1) by means of an upsetting body (3, 3', 3");

   c) upsetting the end of the pipe (1), as a result of which the outer jacket surface is formed radially to the outside in a region adjacent to the face surface (5);

   
   with at least a partial region of the face surface (5) of the pipe (1) being deformed against the direction of upsetting towards the upsetting body, characterized in that the face surface (5) of the pipe (1) is deformed starting from its outer circumferential edge (23) against the direction of upsetting.
7. A method according to claim 6, characterized in that the outer jacket surface of the end of the pipe is shaped conically towards the outside, with the diameter of the conical section increasing in the direction of upsetting.
8. A method according to claim 6 or 7, characterized in that the pipe end is deformed radially towards the outside also in the region of the clamping jaws.

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