EP1256394B1 - Profile bending machine with mandrel - Google Patents

Abstract

The bending tool for tubes (8) and similar includes a mandrel shaft (15) movable into and out of the tube cavity. During bending, it is on a bend line between at least two opposed rollers (11-14) applying bending pressure. The mandrel shaft is highly resistant to pressure and wear, at least in the region of the bend line.

Description

The invention relates to a profile-mandrel shank tool according to the preamble of claim 1.

It is known to use a so-called profile-mandrel shank bending tool for the effective bending of open and closed hollow profiles and normal profiles on bending machines.

The purpose of a profile-mandrel shank bending tool is to guide the profile-mandrel shank tool in the interior of the profile to be bent and in particular in a region between a roller center roller and the support roller.

This profile-mandrel shaft should thus avoid an inadmissible radially inwardly or laterally and inwardly inwardly and outwardly directed deformation of the hollow profile during the bending process. It is preferably adapted in its shape to the profile to be bent and is held by a mandrel which is fixed in a mandrel station.

During the bending process, therefore, the profile-mandrel shank tool remains in said area to support the profile to be bent in the interior.

However, there are provided axial drives for the mandrel bar, which make it possible to withdraw the entire mandrel shaft in certain operating conditions.

An inventive mandrel shaft is used for any bending machines. So it does not matter here, for example, to use three-roller bending machines. It can also after such Dornschäfte The invention can be used for core roll bending machines, as well as for pipe profile bending machines, mandrel bending machines and others.

Likewise, of course, all other arbitrary bending machines may be used, e.g. Stretch bending machines, where it is important to always keep the mandrel shank in the bending line, whereby also used rotating mandrel shafts, which run with the bending of the profile, depending on the machine design.

Thus, the invention is generally directed to a mandrel station having at least one mandrel bar and a mandrel shaft disposed at the forward end of the mandrel bar. There may also be several mandrel stations with mandrel bars, and there may be oppositely directed mandrel stations with mandrel bars, so that so with respect to the bending zone opposite mandrel shafts are present.

In multi-chamber profiles also several parallel mandrel shafts are used.

In certain bending tasks and certain bending machines very high Auswalzkräfte exist on the profile to be bent, which is associated with the problem that there is a very high friction between Dornschaftoberfläche and profile inside.

So far, there was no solution that protected the mandrel shank in this area against undue deformation or even destruction. Rather, the problem has not posed in the way in the known bending machines, since such high rolling and frictional forces on the profile and thus also on the arranged in profile mandrel shaft does not work.

In the novel bending machines, which preferably work with four rollers, it is essential that in addition to the bending task still an additional rolling the profile takes place in the bending zone. In this bending process, a Auswalzfließeffekt in the outer region of the profile superimposed on the bending process, in a reduced form, the rolling flow effect also occurs on the inside of the profile. This so-called roll bending process generates high frictional or friction forces with possibly very high resistance to movement of the profile to be bent, which can lead to the destruction of the profile or at least excessive surface damage to the interior of the profile to be bent. Due to poor sliding properties on the mandrel shaft, the bending quality is also badly affected.

With the DE 296 01 464 U1 discloses a bending mandrel for a bending tool for pipes, which is formed at the end with a ceramic disk with a convexly curved lateral surface, wherein the ceramic screw is fixed with a dowel on an end face of the mandrel. During the bending process of the tube, the ceramic disc of the bending mandrel slides without the addition of lubricant along the inner wall of the tube to be bent.

This invention has the disadvantage that the bending pressure forces in the bending line arising during the bending process are uniformly distributed to the circumference of the ceramic disk only during the forming of round pipes. When bending flat or asymmetrical profiles, the pressure-poor ceramic disk is not sufficient to absorb the relatively high bending pressure forces during the bending process.

With the DE 296 00 728 U a mandrel is disclosed on pipe cold bending machines, wherein the mandrel described here is lubricated during the bending process of pipes via a mandrel lubrication in order to keep the considerable wear of the mandrel and damage to the pipe inner wall as low as possible. The lubricant is in this case pressed by means of a lubrication hole through the mandrel rod in the mandrel, escapes through a lubrication hole located at the top of the mandrel shaft and is distributed over a lubrication groove on the circumference of the mandrel shaft. A subsequent ball joint mandrel at the front end of the mandrel maintains the tube cross-section approximately upright and is used as a shaping means in the present invention.

This invention has the disadvantage that a lubrication, especially in the area of the bending line, which is subjected to high bending pressure forces, is not disclosed. Here only the supply of large quantities of a lubricant ensures adequate lubrication in general. Furthermore, just in the area of the bending line on the front end side of the mandrel shaft is not lubricated, but far behind.

With the DE 295 03 764 U1 discloses a Faltenglätter on tube bending machines, which slides past during the deformation of pipes on the inside of the tube. Due to high contact forces during the bending process, the pipe is at the Tube inner wall smoothed by means of wrinkle straightener shell. The high wear of the Faltenglätters is reduced by lubrication by means of lubricant glands in the Faltenglätter, which wet the tube-contacting surfaces with the lubricant.

The disadvantage of this invention is that the wrinkle-smoothing shell can absorb only to a limited extent the bending compressive forces occurring during deformation and that a specially associated fold-smoothing shell must be used for each tube dimension. Furthermore, a targeted lubrication in the bending line is not disclosed.

The invention is therefore the object of developing a profile-mandrel shank tool of the type mentioned so that it can absorb the highest pressure loads, consistently good sliding properties and even regardless of temperature influences ensures uniformly high bending speeds of a profile to be bent.

This object is solved by the features of claim 1.

With the given technical teaching according to the invention, therefore, the significant advantage is achieved that as it were a reinforcement of the mandrel shaft is provided at least in the region of the bending line. This provides the following advantages:

The mandrel shaft can now absorb the highest pressure loads, because according to the invention, at least in the bending line, an area is reinforced.

He has consistently good sliding properties at different pressures, because preferably this area is equipped with correspondingly good sliding properties.

It can be bent so different materials, such. Alu with its alloys, Cu, Mg, steel, Cr-Ni-Mo steels, titanium, magnesium etc.

Another advantage is that high speeds of the continuous profile are ensured at the same time high degrees of deformation.

With the given technical teaching, therefore, there is the advantage that due to the armored area a low wear, that is a high wear resistance of the mandrel shaft is ensured.

Thus, a conservation of the material to be bent in its overall construction is also achieved.

The resulting from the rolling at the bending line flow in the structure of the profile to be bent supports the bending process itself to a great extent. At the outside of the arch profile of the stretching process is supported, on the inside of the arch profile of the upsetting process is supported. In Profilausßen- as well as in profile interior of the microstructure flow during the bending process by the superimposed rolling process with the active support of the mandrel shank tool is supported so advantageous that despite the highest material stress micro- or macrocracks in the structure can be prevented.

The formation of a highly wear-resistant region on the mandrel shaft can be made in various embodiments.

In a first preferred embodiment, the invention provides that the mandrel shaft consists of a two-part part, namely a rear one Guide shaft on which optionally interchangeable a front mold head is attached.

The forming head is now designed to be highly resistant to wear, at least partially in the region of the bending line, whereby such a region can take place by reinforcing the forming head in this area.

The reinforcement of the mold head in this area can be done for example by the attachment of hardened webs in the forming head or hardened inserts on the mold head or in such a way that the mold head is formed entirely of a highly pressure-resistant and wear-resistant material.

In a second embodiment of the present invention, it is provided that the mandrel shaft is again formed in two parts and consists of the rear, relatively inexpensive material which does not have to withstand high pressure loads and from a front area which is reinforced by wear sliding plates.

The wear sliding plates are accommodated as insert plates in corresponding guides on the front part and are preferably formed of a sintered metal.

These wear plates have excellent pressure absorption capacity, are highly tempered, have a very smooth surface and are extremely resistant to pressure. They are characterized by a high material density, which leads to the best possible surface quality of the profile to be bent.

The said wear sliding plates are held by a front clamping plate, which bias the wear sliding plates both in the radial direction inwardly and secure against lifting.

In a third embodiment of the invention, it is provided that the mandrel shaft is formed with one or more rolling elements, which are arranged at least in the region of the bending line. Such rolling elements may e.g. Be balls that are freely rotatably guided in a ball cage, but it can also be individual balls, which are arranged in corresponding ball mounts on the forming head, and it may also be a total of ball bearings, which are received in corresponding bearing elements.

Instead of the ball elements mentioned, it is of course also possible to use barrel elements, cylinder elements or combinations of these rolling elements.

In a fourth embodiment, it may be provided that instead of the freely rotatably mounted rolling elements other rolling elements are used, which are rotatably mounted on associated axes of rotation. These rolling elements can in turn be designed as cylindrical rollers, tapered rollers, barrel rollers or the like.

Likewise, a combination of the aforementioned freely guided ball or rolling elements can be used with mounted on rotary axes ball or rolling elements.

In this case, the rolling elements mounted on axles only take up positioning of the mandrel shaft in the interior of the profile to be bent, while the actual high rolling pressures are absorbed by the freely guided rolling elements in connection with their rolling bed.

Essential in the invention is therefore that at least the region of the mandrel shaft, which lies in the bending line, is provided with said reinforcing measures. Of course, the reinforcement of the mandrel shaft in the bending line also by others Armierungskörper be realized, in particular by diamond-occupied support or reinforcing plates, by high-strength steels, or by ceramic elements, which are also able to accommodate the high Auswalzdrücke.

In a further development of the invention, it is provided that additional lubrication of the mandrel shaft takes place at least in the region of the bending line.

This particular lubrication is to enjoy protection in isolation, that is, regardless of whether the mandrel shank is reinforced or not, and it should enjoy protection in another embodiment, in combination with the reinforcement.

The lubricating system according to the invention preferably consists of an air-oil lubrication system, wherein in a first embodiment in the region of the mandrel station, a lubricating device is arranged, the lubricating oil under pressure 30 bar through the mandrel and through the mandrel shaft to the front end of the mandrel shaft transported, with the pressure oil and separated from this compressed air is carried. The two streams air-oil are then transferred in the front region of the mandrel shaft in oil microdroplets, without causing nebulization. The entrained air stream tears the oil droplets flowing out of a nozzle, swirls these into an oil-air mixture and conveys them into lubrication pockets arranged radially on the outer circumference of the mandrel shaft, where the resulting pressure of about 6 bar builds up and the oil-air mixture on the Inner circumference of the profile to be bent in the region of the mandrel shaft acted upon.

It is important that the lubrication pockets are tapered conically in the conveying direction and point with their narrowest areas on the reinforcing zone, so that in this Armierungszone a very thin lubricant film is generated, which lubricates the high-strength region arranged there in an excellent manner.

The lubrication pockets are thus formed in the bending direction in front of the highly wear-resistant region of the mandrel shaft and therefore lead to the highly wear-resistant region only a thin lubricating film.

Moreover, it is preferred that during retraction of the profile in the bending machine even the lubricating device can be set in motion, so that when retracting the profile - contrary to the bending direction - already the entire interior of the profile is acted upon with the lubricating film according to the invention.

In the case of particularly high demands on the lubricating properties of the wear region on the mandrel shank, the aforementioned oil-air mixture can then additionally be applied to the wear plates or even to this high-strength region during the bending operation.

Thus, the invention provides for two different method arrangements, namely a first method in which the profile is lubricated only during retraction and then no longer lubricated separately during the bending process, which happens in particular for lighter forming work.

In another method state, however, the profile to be bent is lubricated both during the intake, as well as during the bending process itself.

Of course, it is possible to form the mandrel shank according to the invention as a profiled shaft, that is, he not only has a reinforced area, but he has profiled longitudinal grooves, which are protected with appropriate reinforcing measures.

Such special measures are required for bending window and door profiles or spaceframe profiles for the automotive sector.

In a further development of the invention, instead of the formation of an air-oil mixture, a simpler lubrication system can also be used in which an oil film is dispensed onto the inside of the profile merely via one or more spray nozzles.

It may be provided that such spray nozzles are arranged at the front end of the mandrel shaft. However, such spray nozzles can also be arranged on the circumference of the mandrel shaft in addition or in isolation.

In the following the invention will be explained in more detail with reference to several execution paths representing drawings. Here are the drawings and their description further features and advantages of the invention.

Figur 1:

schematisiert eine Ansicht einer Biegemaschine mit einem eingesetzten Profil-Dornschaft-Werkzeug;

Figur 2:

schematisiert eine Seitenansicht einer ersten Ausführungsform eines Dornschaftes;

Figur 3:

eine zweite Ausführungsform eines Dornschaftes;

Figur 4:

eine dritte Ausführungsform eines Dornschaftes;

Figur 5:

eine vierte Ausführungsform eines Dornschaftes;

Figur 6:

vergrößerte Schnittansicht der Darstellung nach Figur 1;

Figur 7:

eine weitere, vergrößerte Schnittansicht des Dornschaftes nach Figur 6;

Figur 8:

eine gegenüber Figur 7 abgewandelte Ausführungsform eines Dornschaftes mit einfacher Druckölschmierung;

Figur 9:

die um 90 gedrehte Ansicht der Figur 8;

Figur 10:

perspektivische Darstellung einer Biegemaschine mit eingesetztem Dornschaft in der Art nach Figur 1.

Show it:

FIG. 1:

schematizes a view of a bending machine with an inserted profile-mandrel shank tool;

FIG. 2:

schematically shows a side view of a first embodiment of a mandrel shaft;

FIG. 3:

a second embodiment of a mandrel shaft;

FIG. 4:

a third embodiment of a mandrel shaft;

FIG. 5:

a fourth embodiment of a mandrel shaft;

FIG. 6:

enlarged sectional view of the illustration after FIG. 1 ;

FIG. 7:

a further, enlarged sectional view of the mandrel shaft after FIG. 6 ;

FIG. 8:

one opposite FIG. 7 modified embodiment of a mandrel shaft with simple pressure oil lubrication;

FIG. 9:

the rotated view of the 90 FIG. 8 ;

FIG. 10:

perspective view of a bending machine with inserted mandrel shaft in the manner of FIG. 1 ,

In FIG. 1 a profile bending machine 1 is generally shown, which consists of a four-roller system in the illustrated embodiment.

At the inlet a support roller 11 is arranged behind the bending direction, a roller 12 and behind the turn in the bending direction, a bending roller 13 is arranged.

These three roles is centered on a center roller 14. The profile bending machine 1 is connected via a bridge 3 with a mandrel station 2.

At the mandrel station 2 a thrust carriage drive 4 and a lubricating device 6 is arranged.

The displaceably driven on the bridge 3 in the direction of arrow 9 thrust slide 5 is penetrated by the mandrel 7, which carries at its front end the mandrel shaft 15 according to the invention.

The mandrel 7 with the mandrel shaft 15 attached thereto at the front end is arranged in the interior of a profile 8 to be bent.

The mandrel 7 is acted upon by a drive, not shown, which is arranged in the mandrel station 2.

The profile 8 to be bent is held by a gripping head 10, which is fastened to the thrust carriage 5.

The lubrication is now carried out by the arranged in the mandrel station 2 lubrication device 6, which is connected via a double tube 16 to a terminal 27, via which the two media pressure oil and compressed air into the interior of the mandrel 7 and thus into the interior of the mandrel shaft 15th be fed.

The FIG. 1 shows schematically that a profile to be bent in the positions 8 ', 8 ", 8"' or 8 "" can be bent.

The FIGS. 2 to 5 show different forms of Dornshäften 15 ad.

In FIG. 2 It is shown that the mandrel shaft 15 a is formed from a rear, little wear-resistant material as a guide shaft 17 which carries a front forming head 19.

This forming head 19 can be interchangeably arranged on the guide shaft 17 and can even be highly wear-resistant and pressure-resistant.

But it can also wear only a region highly wear resistant, which corresponds approximately to the Auswalzbereich 20 the auswalzenden profile.

This Auswalzbereich 20 is formed in the bending direction in front of and behind the bending line 18 of the profile to be bent.

In brackets are in FIG. 2 the positions of the rollers 12, 13, 14 used in each case.

This position information also applies to the other representations in the FIGS. 3 to 5 ,

Important is so in the embodiment according to FIG. 2 in that either the mold head 19 as a whole consists of a highly wear-resistant, pressure-resistant material or is merely reinforced in a rolling region 20 with appropriate measures or is designed to be highly wear-resistant.

In the embodiment according to FIG. 3 It is shown that at least the Auswalzbereich 20 is reinforced with corresponding wear sliding plates 21. These are the plates mentioned in the general part of the description, which consist of a highly wear-resistant and pressure-resistant material.

These wear sliding plates 21 may be arranged either only on the upper and lower sides of the mandrel shaft 15, as it is FIG. 3 or they may also extend evenly around the circumference of the mandrel shaft in the rolling region 20.

Said wear sliding plates 21 are held in position by a front clamping plate 22 and biased. They are thus secured against radial lifting.

In the embodiment according to FIG. 4 Schleiß sliding balls 23 are arranged, which are received in corresponding ball tracks 24.

It has already been pointed out in the general part of the description that they are not necessarily sliding balls; general rolling elements can be used.

Likewise, it is not necessary for the solution that said wear sliding balls extend around the circumference of the mandrel shaft 15 around, they may also be present only partially or partially and arm only the highly wear-resistant areas of the mandrel shaft.

The FIG. 5 shows a mandrel shaft 15 d, in which wear sliding rollers 25 are mounted in the axis of rotation 26.

It goes without saying that one execution after FIG. 4 with the execution after FIG. 5 can be combined.

Likewise, all other versions after the FIGS. 2 to 5 be combined with each other.

In FIG. 6 an enlarged view of the front end of the mandrel 7 is shown - as in FIG. 1 shown.

It is shown that in the vicinity of the mandrel station 2, a terminal 27 is provided, in which the double tube 16 opens. Further, the clamping head 10 is shown with the mandrel bar 7, which carries at its front end a mandrel shaft receptacle 28 in which the mandrel shaft 15 is fixed.

The mandrel shaft 15 preferably has a central channel 29, which is designed as a double channel, to guide the two media air and oil separated from each other.

At the front region of the channel 29, a nozzle 32 is arranged.

The FIG. 7 shows an enlarged view of the situation FIG. 6 with the enlarged front end of the mandrel shaft 15th

It can be seen that the mandrel shaft is equipped in its formation as a mandrel shaft 15 b with each other opposite wear sliding plates 21. These wear sliding plates are each received in dovetail-shaped receiving pockets 43 and abut with obliquely radially inwardly directed cone clamping surfaces 45 to a corresponding likewise obliquely formed clamping plate 22.

The clamping plate 22 is biased by a clamping screw 44 against the wear sliding plates 21. In this way, these wear sliding plates 21 are biased in their receiving pockets 23 and secured against lifting.

It has already been pointed out in the general description part that sufficient with this Armierungsmaßnahme already sufficient reinforcement of the mandrel shaft in bending simple cross-sections.

In the bending of round tubes then preferably reinforcing rings are used, that is, the reinforcing measures according to the FIGS. 2 to 5 are then evenly distributed around the circumference of the mandrel shaft.

For more difficult cross-sections or at higher degrees of deformation, however, the lubricating system according to the invention is used, which is described below with reference to FIGS. 7 to 9 is described.

The aforementioned channel 29 is according to FIG. 7 from a coaxial, outer annular channel 30, in which the compressed air at a pressure of eg 4 - 10 bar is guided, while separated from an oil hose 31 is guided in the center of the channel 29, which opens into a front nozzle 32.

The oil is conveyed at a delivery pressure of eg 20-30 bar and exits in the form of oil droplets from the nozzle mouth of the nozzle 32.

At the same time these oil droplets 40 are enveloped by the air flow in the direction of arrow 39 and entrained and reach a mixing chamber 33, which is preferably formed conically widening.

In the flow direction of the mixing chamber 33 is followed by an approximately cylindrical vortex chamber 34, in which there is a swirling of the oil droplets 40 with the air flow 39, so that the oil droplets 40 are carried by the air flow. The air flow thus serves only as a transport medium for the oil droplets 40, so that the air-borne oil flow in arrow directions 41 in obliquely adjoining the mixing chamber 33 channels 35 occurs.

These channels 35 are directed obliquely in the bending direction to the front and open radially outward in lubrication pockets 36. These lubrication pockets are in accordance with in cross section FIG. 7 arranged approximately triangular profiled, extend approximately over the entire width of the area to be lubricated, as for example in FIG. 9 is shown.

At this approximately in cross-section approximately triangular profiled lubrication 36 close conically tapered in the direction of bending further lubrication pockets 37, which also approximately in cross section FIG. 7 are triangular-shaped profiled, and run very narrow and there allow a very thin lubricating film 42.

This lubricating film 42 is only about 10 to 500 .mu.m thick and is characterized in that it runs parallel in the region of the wear sliding plates, so that they are lubricated evenly over their surface.

The wedge shape of the lubrication pockets 37, which are directed to the wear sliding plates 21, is allowed to form in the region of Schleiß sliding plates on the outer surface, a relatively constant lubricating film 42 with said thickness. In Auswalzbereich, in the area of Schleiß sliding plates 21, so a particularly thin and highly durable lubricating film 42 is generated. The excess air flows in the direction of arrow 54 past the non-reinforced areas and flows forward into the interior of the profile. 8

Likewise, the air can also flow backwards in the opposite direction to the arrow 54 in the direction of the mandrel station 2 and escapes at the clamping head 10.

If one defines the bending direction with arrow 38, it is thus ensured that in the bending direction in front of the wear sliding plates 21, a highly viable lubricating film 42 is transported into the nip and provides excellent lubrication of the mandrel shaft 15 a - d.

With the direction of the arrow 46 it is shown that the aforementioned clamping plates 22 hold down and bias the wear sliding plates 21 in the direction of arrow 46.

The FIGS. 8 and 9 show a simplified lubrication system that works without turbulence of oil and air.

Here, the oil-air mixture is already generated in the lubricating device 6 at the mandrel station 2 and fed via said channel 29 into the mandrel shaft 15, where this mixture enters the lubrication channel 47 and a check valve 48 passes.

The check valve 48 consists of a spring-loaded valve ball, which closes the lubrication channel 47 against the pressure in the lubrication channel 47.

At elevated pressure thus the check valve 48 lifts and the oil-air mixture flows straight through a threaded tube 51 forward in a nozzle head 50, where it is distributed over distributed nozzles 52 against the inside of the hollow section 8.

In an alternative embodiment, it is shown that the aforementioned channel 35 are closed by closure pieces 49, so that therefore this oil-air mixture passes only centrally through the channel 47 and 51 in the nozzle 52.

If, on the other hand, the closing pieces 49 are removed, the channels 35 are also acted upon and consequently the previously mentioned lubricating pockets 36, 37 are supplied with lubricant.

Thus, it can be generated from the nozzle 52 a directed against the wall of the hollow profile spray 53 as well as in the region of the lubricating pockets 36, 37, a corresponding spray 53.

This situation is in FIG. 9 shown again, wherein in plan view, the transverse extent of the lubricating pockets 36, 37 can be seen, as in the embodiment according to FIG. 7 is present.

The FIG. 10 again generally shows the perspective view of the entire bending machine with the mandrel station 2, where it can be seen how the said parts are associated with each other.

drawing Legend

1

Profile bending machine

2

Dorn station

3

bridge

4

Thrust carriage drive

5

Traverse frame

6

Schmiervorrichtung1

7

mandrel

8th

Profile, 8 ', 8 ", 8"', 8 ""

9

arrow directions

10

chuck

11

supporting role

12

roller

13

bending roller

14

Central role

15

Dornschaft a - d

16

double hose

17

guide shaft

19

elastic line

19

forming head

20

Auswalzbereich

21

Wear-sliding plate

22

clamp

23

Wear-slide ball

24

ball track

25

Wear-caster

26

axis of rotation

27

Connection

28

Dorn stem receiver

29

channel

30

annular channel

31

oil hose

32

jet

33

mixing room

34

swirl chamber

35

channel

36

lubrication pocket

37

lubrication pocket

38

arrow

39

airflow

40

oil droplets

41

arrow

42

filming

43

receiving pocket

44

clamping screw

45

Conical clamping surface

46

arrow

47

lubrication channel

48

check valve

49

closing piece

50

nozzle head

51

threaded pipe

52

jet

53

spray

54

arrow

Claims (22)

1. Profile mandrel shaft tool for bending open or closed hollow profiles (8), containing a mandrel shaft (15) with a shaped head (19; 22), which can be guided by means of a conveying device into and out of the interior of the hollow profile (8), the shaped head (19; 22) being located, during the bending process, on a bending line (18) between at least two opposed rollers (11 to 13; 14) applying the bending pressure and being configured in a manner highly resistant to pressure and wear, at least in the region (20) of the bending line (18), characterised in that the reinforced region (20) is formed by applying hardened insertion pieces in the shaped head (19).
2. Profile mandrel shaft tool according to claim 1, characterised in that during the bending process, the mandrel shaft is located on a bending line between at least two opposing rollers applying the bending force.
3. Profile mandrel shaft tool according to claim 1 and 2, characterised in that the mandrel shaft (15) is configured in two parts, namely a rear guide shaft (17), on which is placed a front shaped head (19; 22), on which the reinforced region (20) configured so as to be highly resistant to pressure and wear is located.
4. Profile mandrel shaft tool according to claim 3, characterised in that the shaped head (19; 22) can be exchanged.
5. Profile mandrel shaft tool according to any one of claims 1 to 4, characterised in that the reinforced region (20) is formed by hardened insertion pieces (21; 23; 25) on the shaped head (22).
6. Profile mandrel shaft tool according to claim 5, characterised in that the hardened insertion pieces (21; 23; 25) are provided in the form of at least one wear-sliding plate (21) and/or at least one wear-sliding ball (23) and/or at least one wear-sliding roller (25).
7. Profile mandrel shaft tool according to claim 6, characterised in that the at least one wear-sliding plate (21) consists of sintered metal.
8. Profile mandrel shaft tool according to either of claims 6 or 7, characterised in that the at least one wear-sliding ball (23) is freely rotatably received in at least one peripheral ball race (24).
9. Profile mandrel shaft tool according to any one of claims 6 to 8, characterised in that the at least one wear-sliding roller (25) is substantially stationary and can be rotated about its own rotational axis (26).
10. Profile mandrel shaft tool according to any one of claims 1 to 5, characterised in that the reinforced region (20) is formed by a shaped head, which is in total formed from a material which is highly resistant to pressure and wear.
11. Profile mandrel shaft tool according to any one of claims 1 to 10, characterised in that the mandrel shaft (15) is lubricated by means of a lubricant at least in the region of the bending line (18).
12. Profile mandrel shaft tool according to any one of claims 1 to 11, characterised in that the mandrel shaft (15) is lubricated by means of a lubricant at least in the region of the bending line (18).
13. Profile mandrel shaft tool according to claim 12, characterised in that the lubricant is present in the form of fine lubricant drops (40) at least in the region of the bending line (18).
14. Profile mandrel shaft tool according to claim 13, characterised in that the lubricant drops (40) are produced by means of spray nozzles.
15. Profile mandrel shaft tool according to claim 13, characterised in that the lubricant drops (40) are produced by means of a gaseous medium, which is supplied to the lubricant.
16. Profile mandrel shaft tool according to claim 15, characterised in that the lubricant is a lubricant oil and the gaseous medium is air.
17. Profile mandrel shaft tool according to any one of claims 11 to 16, characterised in that the lubricant is present under a pressure of about 2 to 10 bar in the region of the bending line (18) on the mandrel shaft (15).
18. Profile mandrel shaft tool according to any one of claims 11 to 17, characterised in that the lubricant is present in at least one lubricating pocket (36, 37) on the mandrel shaft (15) in the region of the bending line (18).
19. Profile mandrel shaft tool according to claim 18, characterised in that the at least one lubricating pocket (36, 37) tapers conically in the conveying direction of the lubricant drops (40).
20. Profile mandrel shaft tool according to any one of claims 1 to 19, characterised in that the mandrel shaft (15) is configured as a profile shaft, with a profile running approximately in the longitudinal direction.
21. Profile mandrel shaft tool according to any one of claims 1 to 20, characterised in that the mandrel shaft (15) can be loaded with lubricant only on being drawn in to the hollow profile (8).
22. Profile mandrel shaft tool according to any one of claims 1 to 21, characterised in that the mandrel shaft (15) can be loaded with lubricant when being drawn into the hollow profile (8) and also during the bending process itself.

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