EP2281643B1 - Assembly for bending tubular workpieces - Google Patents

Description

The invention relates to an arrangement for bending tubular workpieces, in which a workpiece is fed to a bending head for bending and is supported during bending in the bending region by means of a mandrel introduced into the workpiece from the inside, wherein the mandrel comprises a mandrel member and a rotor, movably seated in the workpiece and the rotor is longitudinally displaceable by means of a feed device in the workpiece.

It has long been known to make pipe bending with highly flexible CNC-controlled bending machines, with support measures being used in the boundary region of the material properties in order to achieve reproducible bending results without material failure. As such supporting measures are the use of internal mandrels, slide rails or Faltenglätter to name, the use of internal mandrels in a tube bending machine specifically the inner support of the tube during bending in the bending area is used. This is to prevent that it can lead to undesirable deformations, cracks, wrinkles or the like on the pipe during bending.

Typically, the internal mandrel assembly consists of a mandrel member secured to a mandrel bar, which in turn connects the mandrel member to a runner connected to a feed mechanism for axially displacing the mandrel member in the pipe. However, this known method usually works only with already separated to appropriate length pipes, which are fed to the bending machine in succession. The inner mandrel is inserted after inserting the workpiece from behind into the tube and positioned in the bending area. The feed device is mounted axially behind the pipe.

However, it is often desirable in the field of small diameter to process endless pipe material from the coil, in which case, however, no inner mandrel from the pipe end ago can be inserted more, so that normally must be bent without internal mandrel. However, this has the consequence that sometimes desired bends with tight bending radii can not be made.

Often very long cut to length workpieces are available, which can not be processed on internal machines with internal spikes, but require special longer machine bodies or just have to be shortened to a corresponding length, but this leads to a high waste content.

Also known are those machines that work directly from the sheet metal material, this first form a tube and then bend it first. The inner mandrel is inserted in the not yet closed pipe area.

Also known is the use of z. As ice as internal mandrel material.

The use of flying mandrels in pipe drawing is known in the art.

So describes the generic EP 1 484 123 B1 a machine in which a pipe is formed from a sheet, which is then formed by bending. The mandrel unit is arranged offset far enough so that it engages from above into the still open profile and thus positioned the mandrel element in the bending area. However, this known method does not work with already closed profiles, such as finished pipes.

Also from the DE 28 16 840 a device is known in which a tube is formed from a metal sheet, which is then reshaped by bending. Here it is proposed to use a frozen or a solidifiable material (ice) for the inner mandrel. However, the use of liquids or other solidifiable materials is actually undesirable, not suitable for all pipe materials and also can not withstand the high pressures during bending.

The US Pat. No. 3,891,952 A describes a device for producing ribs on tubes by rollers. In this case, an inner mandrel in the tube is used as a counter-holder against the rolling pressure, which is fixed axially via an outer magnet in a corresponding position. However, the inner mandrel is not used in conjunction with bending machines.

The same applies to the tube pulling device from the DE 37 39 730 C1 in which the pipe drawing is carried out with a magnetically held mandrel. Again, this is not an internal mandrel for bending machines.

The invention now aims to provide an arrangement for bending tubular workpieces of the type mentioned above, with the arbitrarily long pipes, even endless tubes from the coil or unilaterally tapered or otherwise shaped pipes, the insertion of the inner mandrel from behind impossible can be bent with internal mandrel, without the use of the internal mandrel device is limited by the workpiece length or the machine length.

According to the invention this is achieved in an arrangement of the type mentioned above in that the rotor consists of a magnetizable material and the feeding device has a corresponding to the position of the rotor outside of the workpiece position attached magnetic device, between the and the rotor, a magnetic adhesion is formed , wherein the rotor can be moved over the magnetic device in the workpiece. Preferably, both the rotor, as well as the magnetic device of a permanent magnet arrangement, which is considered within the meaning of the invention by the term "magnetizable material" as miter caught.

According to the invention, the feed device is no longer mounted axially behind the workpiece (pipe), as has hitherto been the case, but is present outside the workpiece in a position corresponding to the position of the rotor. The present invention thus created magnetic adhesion between the magnetic device and the rotor now gives the ability to contact by a corresponding change in the magnetic field in the magnetic device, such as by a movement thereof in the longitudinal direction of the workpiece or by generating a traveling magnetic field in the axial direction of the workpiece To cause displacement of the rotor within the workpiece. This can be withdrawn from the coil, endless tubes as well as very long cut to length tubes or other tubes in which an insertion of the mandrel from behind is impossible. still bend with inner spine. At the same time results in a fairly compact design of the arrangement according to the invention, which is also extremely effective function.

The arrangement according to the invention is also of surprisingly simple construction, hardly susceptible to interference, works with a very good efficiency and is very inexpensive hestell- and can be used.

In a particularly favorable embodiment of the invention, the magnetic device is mounted displaceably in the longitudinal direction of the workpiece, for which purpose it preferably to a drive, for. As a pneumatic cylinder, a spindle drive o. Ä. Is connected. If so moved the actuator in the longitudinal direction of the workpiece causes the magnetic Frictional connection between the magnetic device and the rotor, that then also the lying inside the tube rotor (which is fixed by the magnetic frictional connection relative to the magnetic device) also moves.

Most preferably, in the invention, the magnetic means is disposed around the outer circumference of the tubular workpiece, advantageously consisting of two halves which are detachably secured to each other in the assembled state, the halves of which are in a diameter plane of the workpiece. To cancel the magnetic force during insertion of the mandrel element into the tube, the two halves of the magnetic device can be moved apart in this embodiment, whereby the introduction of the rotor and the mandrel element in the tube is particularly easy to carry out.

A preferred embodiment of the invention is also the fact that the magnet assembly as well as the rotor in the longitudinal direction of the tubular workpiece are each layered by spacers of non-magnetizable material axially separated permanent magnets, each having their axially facing sides have a same polarity. In this case, the permanent magnets of the rotor, in particular, preferably have opposite magnetic poles compared to permanent magnets of the magnetic device assigned to them on the outside of the workpiece, viewed in the axial direction of the workpiece.

In this way, according to the required feed force for the rotor a plurality of magnets can now be arranged one behind the other, wherein, preferably, the same pole is present at the left and at the right end of the rotor, so that the direction of the rotor when it is inserted into the pipe is not important plays. This is achieved by, in an advantageous embodiment of the invention, the rotor and the magnet device, along the longitudinal axis of the workpiece, each comprise an even number of permanent magnets, which then ensure that the poles of the first and the last magnet are the same poles.

In the invention, the magnetic device can also be advantageously designed as an electromagnet. Most preferably, in this case, the magnetic device is formed so that in her, viewed in the axial direction of the workpiece, a migrating magnetic field is generated by which the rotor can be moved in the longitudinal direction in this according to the operation of a linear motor, without causing the magnetic device in turn should be moved. In this case, however, the magnet device must be formed significantly longer than the rotor seen in the axial direction of the workpiece. The advantage of such a structure is the fact that no further drive devices for Method of magnet assembly are more needed and the rotor can be used without any problems when the magnetic field is switched off.

In another embodiment of the invention, the rotor is connected to the mandrel member via a mandrel. A particularly advantageous embodiment of the invention is also achieved in that the mandrel element in the workpiece during the bending process reversing and / or about its longitudinal axis is rotationally movable, which can be easily achieved in the formation of the magnetic device as an electric motor by a corresponding control of the same. As a result, the inner mandrel element is not positioned at a specific point in the bending area during the bending process, but can be reversibly (oscillating about, oscillating or swinging) in the bending area and / or rotating about its longitudinal axis. Such oscillatory motions may be at a slower rate (such as to reshape bend with a mandrel) or at a high frequency (eg, to reduce friction between the inner mandrel and tube, to hammer on the bend area, or to affect the flow behavior of the tubing material ) operate.

Advantageously, the radial gap between the two is chosen so small in the invention in coaxial alignment of rotor and magnetic device, that the workpiece is still free to move freely through it. Because the gap between rotor and magnetic device should be as low as possible in the interest of the greatest possible power transmission, which is why it is endeavored to keep it as small as possible; However, it should be so large that the workpiece to be machined in each case is just freely displaced through the gap formed.

In principle, however, it should be noted once again that in the invention the particularly notable advantage is achieved that namely between the inner mandrel (with the mandrel element and the rotor) and the magnetic device no mechanical connection is more necessary (and does not exist).

• Fig. 1 eine schematische Prinzipdarstellung einer mit einer erfindungsgemäßen Innendornanordnung versehenen Biegemaschine, von oben gesehen;
• Fig. 2 eine schematische und vergrößerte Detailansicht der Ansicht aus Fig. 1, jedoch in teilweise geschnittener Darstellung der dort gezeigten Biegemaschine;
• Fig. 3 eine erste Ausführungsform von Magneteinrichtung und Läufer in Form von Permanentmagneten;
• Fig. 4 die Anordnung der Magneteinrichtung in der Darstellung gemäß Fig. 3;
• Fig. 5 eine Vorderansicht der Innendorneinrichtung gemäß Fig. 3, und
• Fig. 6 eine zweite Ausführungsform der Innendorneinrichtung.

The invention will now be explained in more detail by way of example with reference to the drawings in principle. Show it:

• Fig. 1 a schematic diagram of a bending machine provided with an internal mandrel assembly according to the invention, seen from above;
• Fig. 2 a schematic and enlarged detail view of the view Fig. 1 , but in a partially sectional view of the bending machine shown there;
• Fig. 3 a first embodiment of magnetic device and rotor in the form of permanent magnets;
• Fig. 4 the arrangement of the magnetic device in the illustration according to Fig. 3 ;
• Fig. 5 a front view of the internal mandrel device according to Fig. 3 , and
• Fig. 6 a second embodiment of the internal mandrel device.

In the following description of the figures, the same reference numbers are used in the individual figures for the same parts.

In Fig. 1 is a schematic view of a bending machine 1 for bending a tubular workpiece 2 in the form of an endless tube material from the coil 3 shown. The bending machine 1 shown has a straightening unit 4 with a plurality of straightening rollers 5 located in different planes and a feed unit 6 with a plurality of feed rollers 7, a separating device 8 for cutting the endless tubular workpiece 2 and a bending tool 9 with a bending mandrel 10, a Faltenglätter 11 and a Slide rail 12.

Instead of the shown feed unit 6 z. B. equally a linear draw with mobile gripping units, a movable collet o. Ä. Are used.

The structure of the bending machine 1 shown so far is an example of a standard construction.

However, a contactless inner mandrel device 13 is now provided here inside the tubular workpiece 2, from the in Fig. 1 only the actuating device arranged around the tubular workpiece 2 in the form of a magnetic device 14 can be seen. The internal mandrel device 13 may in principle be attached at any point along the tubular workpiece 2 between the coil 3 and the bending tool 9, such. B. also between the feed device 6 and the bending tool. 9

Fig. 2 now shows a slightly enlarged, partially cut neckline Fig. 1 , In addition to the bending tool 9 and the feed unit 6, the entire inner mandrel device 13 can now also be seen here.

The magnetic device 14 allows, as will be explained below in more detail, a displacement of the tubular workpiece 2 slidably mounted mandrel element 15, which in the form of z. B. a stubble, a mandrel, a ball mandrel, a spoon mandrel, a special mandrel o. Ä. Is formed and connected to a rotor 16 via a mandrel 17.

Via the magnetic device 14, the rotor 16 can be displaced in the axial direction X in the tubular workpiece 2. The rotor 16 and the magnetic device 14 are designed so that when coaxial arrangement of the two to be machined tubular workpiece 2 can be pushed through the remaining radial gap 18 just. The gap 18 between the rotor 16 and the magnetic device 14 should be as small as possible in the interest of a good and large power transmission. The inner mandrel can also be embodied without a mandrel rod 17, namely if the magnetic device 14 is provided directly behind the bending tool 9, in which case the mandrel element 15 passes directly into the rotor 16.

Now reference should be made to Fig. 3 in which a first embodiment of magnetic device 14 and rotor 16 is shown in an inventive arrangement.

In this embodiment, both the rotor 16, as well as the magnetic device 14 with a plurality of axially juxtaposed X in the axial direction of permanent magnets 19 are provided, 19 spacers 20 are provided from non-magnetizable material between the individual permanent magnets. When inserted inner mandrel of the rotor 16 is fixed by the magnetic device 14 in the axial direction X. To move it and thus the inner mandrel, a drive 21 is provided, such as in the form of a pneumatic cylinder, a spindle drive o. Ä., Which is connected to a coupling point 22 to the magnet device 14. By the drive 21, the magnetic device 14 can be moved in the axial direction X, whereby then due to the magnetic force foot and the inside of the tubular workpiece 2 lying rotor 16 (and with it the entire inner mandrel) are moved.

This structure allows a very compact design of the magnetic device 14, but requires a separate drive device 21 and special provisions for inserting the inner mandrel, since the magnetic force can not be switched off.

The arrangement of the polarity (north / south) of the permanent magnets 19 is in Fig. 4 shown. The rotor 16 consists of a first magnet 19a, which has a south pole on the left and a north pole on the right. This is followed by a spacer 20 and the second magnet 19b, but now left with its north pole and right with its south pole. Thus, according to the required feed force several permanent magnets 19 layered axially be arranged one behind the other. Ideally, the same pole is at the left and at the right end of the rotor 16, so that the direction of the rotor 16 when inserted into the tubular workpiece 2 does not matter. The permanent magnets 19c, 19d, etc. of the magnetic device 14 are in principle identical as arranged in the rotor 16, wherein the pole position opposite to the rotor 16, however, is reversed, as this Fig. 4 shows what is pointed out.

Fig. 5 shows a possible structure for inserting the rotor 16 in the tubular workpiece 2 in a view parallel to the axial direction X. It can be seen here that the magnetic device 14 consists of an upper half 23 and a lower half 24, which moved apart to release the magnetic force can be (see arrow directions), so that the inner mandrel can be introduced into the tubular workpiece 2.

A slightly different construction of the internal mandrel device 13 or the magnetic device 14 shows Fig. 6 ,

In this embodiment, the internal mandrel device 13 is designed as a linear motor. In the magnetic device 14 windings 25 are provided, by means of which a magnetic traveling field can be generated, in the axial direction X. The rotor 16 is, as in the previous embodiment, provided with permanent magnets 19, but now no longer by a moving magnetic device 14, but moved by the magnetic traveling field in the axial direction X. The advantage of such a structure is that no further drive device for moving the magnetic device 14 is required more and the rotor 16 can be easily inserted into the tubular workpiece 2 at any time when the magnetic field is switched off. However, this structure requires a much larger footprint for achieving the same feed force as in the previous embodiment.

But it is also readily possible to make a combination of the two solutions described by z. B. the solenoid of the magnetic device 14, as in Fig. 6 is shown, in addition to a drive (not shown) in the axial direction X can be moved ("movable solenoid"), as in the magnetic device 14 according to FIG. 3 is shown.

The function of the embodiments illustrated in the figures is as follows: For bending a tubular workpiece 2 from the coil 3 with an internal mandrel device 13, the coil 3 is first provided on a reel behind the bending machine 1 and inserted into the bending machine 1 between the feed rollers 7.

Before the first bending operation, the inner mandrel (mandrel element 15, mandrel rod 17 and rotor 16) is then inserted from the front into the tubular workpiece 2 until the rotor 16 is in the region of the magnetic device 14. For this purpose, either the solenoid 25 is turned off or the halves 23, 24 of the magnetic device 14, as indicated by the arrows in Fig. 5 shown, ripped apart.

After positioning the inner mandrel in the tubular workpiece 2, the halves 23, 24 of the magnetic device are then moved together or the electromagnet 25 is activated and thus fixes the inner mandrel. As soon as the bending process begins, the inner mandrel is advanced or retracted via the magnetic device 14 in the axial direction X. To separate the tubular workpiece 2, the inner mandrel must be withdrawn so far that the moving cutting blade of the separating device 8 can not collide with the mandrel element 15.

The mandrel element 15 can support the tubular workpiece 2 in the counter-blade when cutting from the inside to keep the deformation low.

However, it proves to be particularly favorable if the inner mandrel is not positioned and remains at a specific point in the bending area during the bending process, but reversely moves (oscillating, oscillating, oscillating) in the bending region and / or rotates about its longitudinal axis. This oscillating motion may be at a slower rate (such as to reshape the bend with a mandrel) or at a high frequency (eg, to reduce friction between the inner mandrel and tube, to hammer action on the bend area, or to influence the flow behavior of the tubing). operate. By turning a particularly uniform wear on the inner mandrel can be achieved.

With the arrangement according to the invention bending of long and endless tubes with inner mandrel is now readily possible, thereby expanding the bendable area for endless tubes. The use of the internal mandrel device is limited neither by the workpiece length, nor by the machine length. There is no mechanical connection between inner mandrel and magnet device, which greatly simplifies the overall structure and also contributes to a high functional reliability.

Claims (13)

1. Assembly for bending tubular workpieces (2), in which a workpiece (2) is fed to a bending head for bending and is supported during the bending operation in the bending region from the inside by means of a mandrel (15-17) introduced into the workpiece (2), wherein the mandrel comprises a mandrel element (15) and a traveller (16) and is seated movably in the workpiece (2), and the traveller (16) is longitudinally displaceable in the workpiece by means of a feed device (14),
   characterised in that
   the traveller (16) consists of a magnetisable material, and the feed device has a magnet device (14) mounted in a position corresponding to the position of the traveller (16) outside the workpiece (2), a magnetic force-based connection being formed between the magnet device (14) and the traveller, wherein the traveller (16) is displaceable in the workpiece (2) by way of the magnet device (14).
2. Assembly according to claim 1, characterised in that the traveller (16) consists of a permanent magnet arrangement.
3. Assembly according to claim 1 or claim 2, characterised in that the magnet device (14) is a permanent magnet arrangement mounted in such a manner that it is displaceable in the longitudinal direction of the workpiece (2).
4. Assembly according to any one of claims 1 to 3, characterised in that the magnet device (14) is arranged around the outer circumference of the tubular workpiece (2).
5. Assembly according to claim 4, characterised in that the magnet arrangement (14) consists of two halves (23, 24) which enclose the tubular workpiece (2) in the assembled state and are fastened to one another in a detachable manner and the separation planes of which lie in a diametral plane of the workpiece (2).
6. Assembly according to any one of claims 1 to 5, characterised in that the magnet arrangement (14) and the traveller (16), in the longitudinal direction (X) of the tubular workpiece (2), are formed of layers of permanent magnets (19) which are separated from one another by spacers (20), wherein their axially facing sides have the same polarity.
7. Assembly according to claim 6, characterised in that the permanent magnets (19) of the traveller (16) have opposite magnetic poles, when viewed in the axial direction (X) of the workpiece (2), compared with their associated permanent magnets (19) of the magnet device (14) arranged on the outside of the workpiece (2).
8. Assembly according to claim 6 or 7, characterised in that the traveller (16) and the magnet device (14) each comprise an even number of permanent magnets (19) along the longitudinal axis (X) of the workpiece (2).
9. Assembly according to any one of claims 2, 4 or 5, characterised in that the magnet device (14) is in the form of an electromagnet (25).
10. Assembly according to claim 9, characterised in that a travelling field can be generated in the magnet device (14) in the axial direction (X) of the workpiece (2), by means of which travelling field the traveller (16) is displaceable in the workpiece (2) in the longitudinal direction (X) thereof.
11. Assembly according to any one of claims 1 to 10, characterised in that the traveller (16) is connected to the mandrel element (15) by way of a mandrel rod (17).
12. Assembly according to any one of claims 9 to 11, characterised in that the mandrel element (15) is movable in the workpiece (2) during the bending operation in a reversing manner and/or in such a manner that it rotates about its longitudinal axis.
13. Assembly according to any one of claims 1 to 12, characterised in that, with a coaxial arrangement of the traveller (16) and the magnet device (14), the radial gap (18) between the two is chosen to be of such a size that the workpiece (2) is just freely displaceable through it.

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