EP3645183B1 - Bridge tool for producing extruded profiled elements of varying cross-section - Google Patents

Description

The present invention relates to a bridge tool for producing extruded profiles with varying cross-sections.

Extrusion is a forming process for producing different geometries, especially bars, tubes and profiles. During extrusion, a compact (block) heated to forming temperature is pressed through a die using a punch. The block is enclosed by a recipient. The external shape of the pressed strand is determined by the die.

The state of the art distinguishes between direct extrusion, indirect extrusion and hydrostatic extrusion.

In direct extrusion, the punch pushes the block along the inner surface of the container towards the die. In indirect extrusion, the container is closed on one side and the die, which is located on the head of a hollow punch, is pressed onto the block from the other side. The strand passes through the punch hole. Its diameter thus limits the circumscribing circle of the profile cross-section. In hydrostatic extrusion, the pressing force is not applied directly to the block by the punch, but via an active medium (water or oil).

The advantages of extrusion are generally the low tool costs and the variety of geometries that can be produced.

Complex hollow profiles made of light metal can be produced using direct extrusion processes using chamber or bridge tools, whereby the bridge tools have a die part and a mandrel part include. As already explained, the outer contour is determined by the die and the inner shape by the mandrel.

The mandrel itself is not connected directly to the extrusion press, but rather to the mandrel part of the tool via support arms or bridges. The block itself is first split into partial strands by the inlet chambers built into the mandrel part and then reconnected in the welding chamber of the die under high pressure and temperature.

With bridge tools, extreme mechanical and thermal stresses occur, which are particularly problematic on the mandrel support arms. Notch stresses can also cause cracks to form at the roots of the mandrel.

The disadvantage of the extrusion processes known from the state of the art is that only profiles with a constant profile cross-section can be produced. This means that the profiles are oversized in many places, since the profiles always have to be designed according to the requirements at the point of highest load over their entire length.

JP-S57 130719 A , which forms the basis for the preamble of claim 1, describes a bridge tool for a device for the direct extrusion of hollow profiles with variable wall thickness, comprising a die and a mandrel element with an axially movable inner sliding mandrel, wherein the end region of the sliding mandrel has different cross sections.

To produce varying cross-sections in an extrusion press, EN 10 02 18 81 A1 a device for extrusion, in which a mandrel is designed to be variable in the axial pressing direction and which has different cross-sections in its end region. Depending on the arrangement of the end regions of the mandrel described therein relative to the die, an annular gap with a different diameter is formed to form different profile cross-sections.

Disadvantageous to a solution according to DE 10 02 18 81 A2 However, although a device comprising a chamber tool is disclosed, which is intended to enable a varying cross section of the extruded profile, the entire mandrel, which has a large length for technical reasons, must be moved axially. The resulting long lever arms cause relatively large oscillations in the mandrel. However, such vibrations prevent the production of profiles with high precision and tight tolerance requirements.

Furthermore, it is disadvantageous that the durability of a mandrel according to EN 10 02 18 81 A1 is reduced. Such a mandrel is subject to high thermo-mechanical stresses during use, which depend in particular on the pressing forces and forming temperatures that occur. The long mandrel support arm in particular is exposed to changing tensile and bending forces, which can be superimposed by local thermal stresses.

The object of the present invention report is now to overcome the disadvantages of the prior art, and in particular to provide a device for producing profiles with a variable profile cross-section with high precision, since only with such high precision can over-dimensioning of the profiles be effectively avoided , whereby the device is designed and set up to optimally withstand the thermomechanical stresses.

This object is achieved according to the invention by a bridge tool with the features of independent claim 1.

The invention is based on the surprising finding that hollow profiles with varying inner diameters can be produced if the mandrel is constructed in several parts, wherein a movable inner sliding mandrel with different cross sections is included at its end regions, the axial movement of which results in a change in the inner cross section of the hollow profile.

It can be particularly advantageous that the inner displacement mandrel has the smallest cross section at its first end, so that an axial displacement of the inner displacement mandrel in the direction of the die or into the die leads to a smaller wall thickness of the hollow profile, since the shaping gap between inner displacement mandrel and die reduced.

The disadvantages of the prior art are overcome by dividing the mandrel into at least two parts. The inner sliding mandrel can be brought into operative connection with drive elements via short lever arms using connecting elements in order to enable axial displacement of the same, so that vibrations of the mandrel are minimized. It can also be provided that vibrations of the inner sliding mandrel can be almost completely prevented by special guide elements.

The inner displacement mandrel enables the creation of hollow profiles with varying cross-sections with high precision.

Movements of the inner displacement mandrel and other elements of the bridge tool according to the invention are referred to relative to the pressing direction. An axial displacement basically describes a displacement in the pressing direction or parallel to the pressing direction, a radial displacement a radial displacement relative to the pressing direction.

It can be advantageous that the mandrel element comprises at least one second axial recess which extends in the axial direction along the second end region of the inner displacement mandrel opposite the first end region of the inner displacement mandrel, wherein a transverse slide arranged perpendicular to the at least one mandrel element is included, which into which at least one second recess is inserted at least in sections, and wherein the cross slide is in operative connection with the inner displacement mandrel, in particular is firmly connected to the inner displacement mandrel.

Such a cross slide can be used to transmit a force from a drive device to the inner displacement mandrel, in which case the drive device can preferably be arranged outside the actual bridge tool, for example on the outer wall of the receiver or the holder of the bridge tool.

In this case, it may be particularly advantageous that the cross slide can be brought into operative connection with at least one drive device directly or by means of at least one cross member, wherein the drive device is designed and configured to move the cross slide and the inner sliding mandrel in the axial direction.

It can also be advantageous if force is transmitted from the drive device to the inner displacement mandrel not only with the interposition of the cross slide, but also if additionally A cross member is arranged between the drive device and the cross slide.

Furthermore, it may be preferred that a first cross member is arranged at a first radial end of the cross slide and a second cross member is arranged at a second radial end of the cross slide opposite the first radial end, wherein the first cross member can be or is operatively connected to a first drive device and/or the second cross member is operatively connected to a second drive device.

By using two cross beams arranged at opposite ends of the cross slide, a uniform, parallel transfer of force from the drive devices to the inner sliding mandrel can take place and at the same time, tilting of the latter can be prevented. Alternatively, it can also be provided that instead of a second drive device, both cross beams can be connected or are connected to a single drive device.

It has proven to be advantageous that the first and/or the second drive device is designed in the form of a linear drive, in particular in the form of a hydraulic cylinder.

It has been shown that hydraulic cylinders in particular have proven to be particularly suitable for generating a linear force in order to enable an axial displacement of the inner displacement mandrel.

According to an embodiment of the invention, it may also be advantageous for the inner sliding mandrel to have a trapezoidal or triangular cross-section in sections in the axial direction in the region of its first end.

The present invention is not limited to the trapezoidal or triangular cross-sections given as examples. Much more Their cross section is determined depending on the number of movable displacement elements.

According to one embodiment, it can be provided that the interior angle or pitch angle β of the trapezoidal or triangular cross-section has a value in the range from 5 to 25°, preferably from 8 to 15°, particularly preferably 10°. The optimal angle can be adapted/selected according to the invention, even outside the preferred ranges, according to the drive or the available installation space to minimize the force requirement (small angle, long displacement path) or to minimize the installation space (large angle, short displacement path).

It can also advantageously be provided that the further pitch angle of the side of the at least one wedge-shaped element facing the inner displacement mandrel is less than or equal to the pitch angle β of the cross section in the region of the first end in the axial direction of the inner displacement mandrel, so that an axial displacement of the inner Displacement mandrel is converted into a corresponding radial displacement of the at least one wedge-shaped element.

According to the invention, in addition to the axially movable inner displacement mandrel, at least one wedge-shaped element can be used to change the inner cross section of a hollow profile, the radial displacement of which relative to the inner displacement mandrel directly influences the wall thickness of the hollow profile.

It has proven to be advantageous that an axial movement of the inner sliding mandrel in the direction of or further into the die leads to a spreading movement of the at least one wedge-shaped element in the radial direction, since the smallest cross-section of the inner sliding mandrel is arranged at its first end.

This has the particular advantage that the high forces that occur do not have to be absorbed exclusively by the inner displacement mandrel, but also by the at least one wedge-shaped element.

Furthermore, due to the almost free design of the at least one wedge-shaped element, the inner cross section and the wall thickness of the hollow profile can be varied independently of the geometry of the inner sliding mandrel.

According to the invention, the wedge-shaped element can have different base areas and the acute angle of the wedge can be formed from two or more sides.

It has proven to be advantageous that at least one second wedge-shaped element is arranged mirror-symmetrically to the first wedge-shaped element on the side of the inner sliding mandrel opposite the first wedge-shaped element.

The use of two wedge-shaped elements arranged in a mirror-symmetrical manner enables the wall thickness on two sides of a hollow profile to be changed simultaneously. It is obvious that more than two wedge-shaped elements can also be used, which can be grouped radially around the inner sliding mandrel.

It has also been shown that the at least one wedge-shaped element is advantageously connected to the mandrel element by means of a first dovetail guide, wherein the at least one first dovetail guide enables a movement of the at least one wedge-shaped element exclusively in the radial direction, wherein the dovetail guide is formed in particular by the mandrel element and the at least one wedge-shaped element.

A first dovetail guide advantageously makes it possible for the at least one wedge-shaped element to be movable exclusively in the radial direction, but not in the axial direction. This leads in particular to the fact that an axial movement of the inner displacement mandrel with its cross section varying in the axial direction leads exclusively to a radial movement of the at least one wedge-shaped element. Furthermore, the tilting of the Wedge-shaped element is prevented and reproducibility of the implementation of the axial movement of the inner displacement mandrel in the radial movement of the at least one wedge-shaped element is ensured.

According to one embodiment of the present invention, it has also proven to be particularly advantageous that the inner displacement mandrel and the at least one wedge-shaped element are connected by means of a second dovetail guide designed in the axial direction, so that an axial movement of the inner displacement mandrel results in a radial movement of the at least a wedge-shaped element is transferred.

The second dovetail guide offers the particular advantage that a secure connection is provided between the inner sliding mandrel and the at least one wedge-shaped element. Furthermore, the second dovetail guide is particularly advantageous because it not only ensures that when the inner sliding mandrel moves towards or into the die, a radial movement of the at least one wedge-shaped element occurs outwards, but also that when the inner sliding mandrel moves in the opposite direction, tensile forces act on the at least one wedge-shaped element in order to reduce the radial spreading of the wedge-shaped element.

Furthermore, it can be provided that the first recess of the mandrel element and the at least one inner displacement mandrel form a third dovetail guide in the axial direction, so that the inner displacement mandrel and the mandrel element are connected to one another by means of a dovetail guide.

This has the particular advantage that tilting of the inner sliding mandrel is prevented even when high forces are applied.

The invention also provides a device for direct extrusion comprising a bridge tool according to the invention.

Finally, the invention provides a use of a bridge tool according to the invention for producing one or more extruded profiles with cross-sections that can be changed in the direction of extrusion in a device for direct extrusion. The invention is therefore based on the surprising discovery that a change in the profile wall thickness during extrusion can be achieved while avoiding the disadvantages of the prior art by axially displacing an inner sliding mandrel by means of a cross slide, which in turn is connected to linear drives by means of two opposing cross beams. If the cross slide is moved axially, the inner sliding mandrel is thus displaced in the axial extrusion direction. The wedge-shaped elements that are operatively connected to the inner sliding mandrel convert this axial movement, preferably by means of a second dovetail guide, into a radial movement arranged perpendicular to the axial movement. This leads to a spreading of the wedge-shaped element or elements, and this wedge movement reduces the shaping gap between the wedge-shaped element and the die and consequently reduces the wall thickness of the hollow profile.

To subsequently increase the wall thickness, the linear drives are moved back to the starting position, i.e. against the extrusion direction. This movement also causes the cross members including the cross slide to be retracted. As a result of this backward movement of the inner displacement mandrel, this displacement is transmitted to the wedge-shaped element or elements via the optional second dovetail guide, so that they move radially in the direction of the inner displacement mandrel. This increases the shaping gap again.

Further features and advantages of the invention will become apparent from the following description, in which embodiments of the invention is explained by way of example using schematic drawings, without thereby limiting the invention.

Fig. 1:

Eine perspektivische Ansicht einer Ausführungsform eines erfindungsgemäßen Brückenwerkzeugs;

Fig. 2

Eine schematische Aufsicht auf das Brückenwerkzeug gemäß Figur 1;

Fig. 3

Eine schematische seitliche Schnittansicht auf das Brückenwerkzeug gemäß Figur 1; und

Fig. 4

Eine perspektive Ansicht einer Ausführungsform eines Dornelements eines erfindungsgemäßes Brückenwerkzeugs.

This shows:

Fig. 1:

A perspective view of an embodiment of a bridge tool according to the invention;

Fig. 2

A schematic view of the bridge tool according to Figure 1 ;

Fig. 3

A schematic side sectional view of the bridge tool according to Figure 1 ; and

Fig. 4

A perspective view of an embodiment of a mandrel element of a bridge tool according to the invention.

In Figure 1 a perspective view of an embodiment of a bridge tool according to the invention is shown. This comprises a receiver 1, on the outside of which two linear drives 2 in the form of hydraulic cylinders are arranged. Each of the linear drives 2 is connected to a cross member 3, which ends on two opposite sides of a cross slide 4 and is positively connected to it. The gap between a mandrel element 5 and the die 6 defines the wall thickness of the hollow profiles to be produced. The die 6 is attached to a pressure plate 7. The mandrel element 5 also comprises wedge-shaped elements 8 and an inner sliding mandrel 9.

In Figure 2 is the bridge tool according to Figure 1 shown in a sectional view. Together with the side view in section Figure 3 The operating principle of a bridge tool according to the invention is clearly visible. The inner displacement mandrel 9 is arranged in a first recess 10, which extends in the axial direction and is followed by a second recess 11 for the cross slide 4. A movement of the linear drives 2 leads to a displacement of the cross members 3 and the cross slide 4 and thus of the inner displacement mandrel 9 in the axial direction. This axial displacement of the inner displacement mandrel 9 leads to a radial movement of the wedge-shaped elements 8 and thus to a change in the gap between the mandrel element 5 and the die 6. This change in the gap changes the cross section of the hollow profile to be produced.

In Figure 4 Additionally, two first dovetail guides 13 for the wedge-shaped elements 8 and two second dovetail guides 14 are shown. These first dovetail guides 13 ensure that the wedge-shaped elements 8 can only move in the radial direction, while the second dovetail guides 14 make it possible for tensile forces to be transmitted from the inner sliding mandrel 9 to the wedge-shaped elements 8 in addition to compressive forces acting radially outward when the inner sliding mandrel 9 is moved.

Claims (13)

1. Bridge-die tool for an apparatus for the direct extrusion of hollow profiles with variable wall thicknesses, comprising a bridge die (6) and at least one mandrel element (5) having a first end, which is directed toward the bridge-die opening, and a second end, which is located opposite the first end, wherein the outer profile contour of a hollow profile is defined by the geometry of the die opening and the inner cross-section of a hollow profile is defined by the at least one mandrel element, wherein

   the at least one mandrel element has at least one recess (10) in which an inner displacement mandrel (9) is mounted in an axially movable manner, wherein the inner displacement mandrel has different cross sections in its first end region facing the first end of the mandrel element,

   characterized in that

   the inner displacement mandrel is operatively connected to at least one wedge-shaped element (8) on or in the region of its first end, wherein an axial displacement of the inner displacement mandrel (9) leads to a radial movement of the at least one wedge-shaped element (8) and thus to a change of the gap between the mandrel element (5) and the bridge die (6).
2. Bridge-die tool according to claim 1, wherein the pitch angle of the side facing the inner displacement mandrel of the at least one wedge-shaped element is smaller than, or equal to, the pitch angle β of the cross section in the region of the first end in the axial direction of the inner displacement mandrel.
3. Bridge-die tool according to claim 1 or 2, characterized in that the mandrel element comprises at least one second axial recess (11), which extends axially along the second end region of the inner displacement mandrel, said second end region being located opposite the first end region of the inner displacement mandrel, wherein a transverse slide (4) which is arranged, in particular more or less, perpendicularly to the at least one mandrel element is included and is introduced, at least in part, into the at least one second recess, and wherein the transverse slide is in operative connection with the inner displacement mandrel, in particular, is fixed to the inner displacement mandrel.
4. Bridge-die tool according to claim 3, characterized in that the transverse slide can be brought into, or is in, operative connection with at least one drive device (2) directly or by means of at least one crossmember (3), wherein the drive device is designed, and intended, to move the transverse slide and the inner displacement mandrel in the axial direction.
5. Bridge-die tool according to claim 4, characterized in that a first crossmember is arranged at a first radial end of the transverse slide and a second crossmember is arranged at a second radial end of the transverse slide, said second radial end being located opposite the first radial end, wherein the first crossmember can be brought into, or is in, operative connection with a first drive device and/or the second crossmember can be brought into, or is in, operative connection with a second drive device.
6. Bridge-die tool according to any one of claims 4 or 5, characterized in that the first and/or the second drive device are/is designed in the form of a linear drive, in particular in the form of a hydraulic cylinder.
7. Bridge-die tool according to any one of the preceding claims, characterized in that
   the inner displacement mandrel has a trapezoidal or triangular cross section, in part, the region of its first end, as seen in the axial direction.
8. Bridge-die tool according to any one of the preceding claims, characterized in that
   at least one second wedge-shaped element is arranged in mirror-symmetrical fashion in relation to the first wedge-shaped element on that side of the inner displacement mandrel which is located opposite the first wedge-shaped element.
9. Bridge-die tool according to any one of the preceding claims, characterized in that
   the at least one wedge-shaped element is connected to the mandrel element by means of a first dovetail guide (13), wherein the at least one dovetail guide provides for movement of the at least one wedge-shaped element exclusively in the radial direction, and wherein the dovetail guide is formed in particular by the mandrel element and the at least one wedge-shaped element.
10. Bridge-die tool according to any one of the preceding claims, characterized in that
    the inner displacement mandrel and the at least one wedge-shaped element are connected by means of an axially formed second dovetail guide (14), and therefore an axial movement of the inner displacement mandrel is converted into a radial movement of the at least one wedge-shaped element.
11. Bridge-die tool according to any one of the preceding claims, characterized in that
    the first recess of the mandrel element and the inner displacement mandrel form a third dovetail guide in the axial direction, and therefore the inner displacement mandrel and the mandrel element are connected to one another by means of a dovetail guide.
12. A direct-extrusion apparatus comprising a bridge-die tool as claimed in one of the preceding claims
13. The use of a bridge-die tool as claimed in one of claims 1 to 11 so that one or more extruded profiles of cross sections which vary in the extruding direction are produced in a direct-extrusion apparatus.

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