EP0615794B1 - Method to produce a plug chamber for cascade drawing of tubes and device for carrying out the method - Google Patents

Abstract

Use is made of a device (15) with a clamping and denting unit (16) and with an end-expansion and ironing unit (17). A starting tube (1) is first of all fixed locally by means of the clamping and denting unit (16). An ironing ring (30) is then moved along a freely projecting end section (31) of the starting tube (1) with the aid of an ironing cylinder (22) of the end-expansion and ironing unit (17), and a mandrel (26) is then driven into the end section (31) with the aid of a mandrel cylinder (21) of the end-expansion and ironing unit (17). Once the mandrel (26) has reached its end position, in which the inside diameter and the outside diameter of the end section (31) are enlarged, the ironing ring (30) is drawn over the end section (31), the outside diameter being reduced to the original outside diameter of the starting tube (1). Following this, the mandrel (26) too is withdrawn from the end section (31) and two dents are produced on the outer circumference of the end section (31) of the starting tube (1) with the aid of the clamping and denting unit (16). Together with a drawing point produced by forming the free end of the starting tube (1), these dents form a plug chamber into which are embedded a plurality of drawing plugs that interact with drawing dies during the cascade drawing. <IMAGE>

Description

The invention relates on the one hand to a method for producing at least two drawing plugs, on the one hand by means of a drawing bar and on the other hand by a plug chamber delimited on the outer circumference of an outlet pipe when cascading pipes made of non-ferrous metals or their alloys.

On the other hand, the invention is directed to an apparatus for performing the method.

From EP 0 353 324 B1 it is known to provide a stopper chamber for pulling plugs directly in the length section behind a pull-up hinge molded onto an output tube. On the other hand, the plug chamber is delimited by a dent that is pressed radially into the pipe material from the outside. The freely moving pull plugs are embedded in the plug chamber and are not lost. The starting pipe can be a press pipe or a rolled or a longitudinally welded pipe.

In order to reduce the outside diameter and the wall thickness, the outlet pipe is moved in several passes through drawing rings that are spaced apart from one another in the opening cross section, the drawing plugs of different sizes then each forming the corresponding abutment.

In order to be able to carry out the cascade perfectly, in the known case the wall thickness of the outlet pipe having a certain outside diameter must be dimensioned such that even taking into account manufacturing tolerances of the primary material such as uneven outside diameter, uneven wall thickness and ovality, the smallest pulling plug in diameter picks up until the takeover Abutment function can move freely in the plug chamber. If this is not taken care of, the pulling plug can be clamped in and the outlet pipe can be torn off. Since each pull until the pulling ring and the pulling plug interact, a hollow pull takes place, in which the inside diameter of the pipe section of the outlet pipe to be reduced in the outside diameter in the area of the plug chamber is reduced and consequently the wall thickness is increased slightly as a result of the upsetting process when it passes through the pulling ring , one has previously been forced to reduce the wall thickness of the outlet pipe in order to ensure that the smallest plug can move freely. However, this reduces the amount of material used and, as a result, reduces the economic output on the finished pipe.

Based on the method described in the preamble of claim 1, the invention has for its object to improve this method and also to provide a suitable device for performing the method that more material can be used per output tube and consequently more finished tube can be achieved without sacrificing quality is.

As far as the procedural part of this task is concerned, its solution consists in the features listed in the patent claim.

With the method according to the invention, a plug chamber with a wall thickness is created immediately behind the drawing bar, which is dimensioned smaller than the wall thickness of the rest of the starting pipe, with the pipe outside diameter remaining the same. As a result, the inside diameter of the plug chamber, taking into account the diameter reductions during the drawing process and the resulting increase in wall thickness, has been brought to an amount which guarantees the freedom of movement of even the smallest diameter drawing plug up to the point in time at which this drawing plug interacts with the drawing ring assigned to it. Due to the special design of the plug chamber, it is now possible to use an outlet pipe that can be dimensioned larger in wall thickness than the outlet pipe previously used and in which the inevitable manufacturing tolerances in the outside diameter, in the wall thickness and in ovality with regard to the freedom of movement of the play no role in the diameter of the smallest drawing plug. In addition, an extension of the outlet pipe in the area of the plug chamber is associated with the stretching of the plug chamber by approximately 20%. This reduces the length of the pipe section required to generate the drawing die. Also the diameter of the Drawbar kept smaller. As a result, the waste of material caused by the drawbar can advantageously be reduced.

Practical tests have shown that the operating weight can be increased by approximately 25%, which is consequently associated with a considerable increase in the output on the finished tube. Now e.g. a press tube with an outer diameter of 80 mm and a wall thickness of 5 mm used, this can be formed in three passes to a finished tube with an outer diameter of 46 mm and a wall thickness of 2.2 mm, which was previously only possible with an output tube with a Outside diameter of 80 mm and a wall thickness of 4 mm was feasible.

The solution of the objective part of the object on which the invention is based is seen in the features of patent claim 2.

Thereafter, a clamping and denting unit on the one hand and a mandrel and ironing unit on the other are assigned to one another in a function-optimized manner. The clamping and denting unit has radially movable clamping jaws and Dell tappets. With the help of the clamping jaws, an exit pipe can be fixed locally, so that, using the mandrel forming part of the mandrel and ironing unit, a length section protruding beyond the clamping and dent unit in the direction of passage of the exit pipe can be thorned out in such a way that both the inside diameter and this area as well as enlarge the outside diameter. After the mandrel has been thorned out, the outer diameter of the thickened length section is stretched to the original outer diameter of the initial tube with the mandrel remaining in the initial tube. Once the ironing ring and the mandrel have been removed from the outlet tube, the clamping and denting unit and the one assigned to it can be used Dell plunger dents are generated on the outlet pipe, which forms a limitation of the subsequent plug chamber. After the drawing plugs have been introduced into the plug chamber, the draw bar is ultimately formed on the free end of the outlet pipe.

In order to be able to displace the mandrel and the ironing ring in the longitudinal direction of the starting tube, the embodiment according to the features of claim 3 provides two mechanically coupled hydraulically actuatable cylinders which have piston rods which can be extended in opposite directions. The cylinder housings are fixed in place. The piston rod of the mandrel cylinder, which can be extended in the direction of the exit pipe or the clamping and denting unit, is connected to the mandrel, which serves to widen the end section of the exit pipe and serves as an abutment for the ironing ring when this end section is stretched. The piston rod of the ironing cylinder, which can be extended in the other direction, is connected to the ironing ring via a linkage which runs parallel to the longitudinal axes of the cylinders. The ironing ring is arranged at the free end of the rod.

To produce the plug chamber at the front end of the outlet pipe in the direction of flow, the outlet pipe is first moved beyond the clamping and denting unit with a length section that takes into account the axial extension of the plug chamber and the drawbar. Then the clamping jaws are placed on the outlet pipe and the outlet pipe is thus fixed locally.

The starting position of the mandrel and ironing unit is such that the mandrel cylinder is retracted and the ironing cylinder is extended. After fixing the output pipe, the ironing cylinder is then in the direction of entry acted upon, so that the ironing ring slides along the end section of the output tube projecting beyond the clamping and denting unit in the direction of passage. After reaching the end position, the mandrel cylinder is loaded in the direction of extension and the mandrel is pushed into the outlet tube, increasing the inside and outside diameter. When the mandrel has reached its end position, the ironing cylinder is loaded in the direction of extension and the outer diameter of the lengthened mandrel is stretched to the original dimension. The mandrel remains in the exit tube. After stretching, the mandrel cylinder is also loaded in the entry direction and the mandrel is pulled out of the exit tube. Then the Dell tappets are moved radially inwards and two dents are created in 180 ° offset. Ultimately, the drawing die is formed on the free end of the length section provided with a reduced wall thickness, if the pulling plugs have previously been inserted into the plug chamber produced by the thickening.

Figur 1

in schematischer Seitenansicht eine Ziehkaskade zur Durchmesserreduzierung eines kupfernen Ausgangsrohrs;

Figuren 2 bis 6

jeweils im vertikalen schematischen Längsschnitt fünf verschiedene Arbeitspositionen einer Klemm- und Delleinheit sowie einer dieser zugeordneten Aufdorn- und Abstreckeinheit;

Figur 7

in der Seitenansicht, teilweise im vertikalen Längsschnitt, den Endabschnitt des Ausgangsrohrs nach dem Aufdornen;

Figur 8

die Darstellung der Figur 7 nach dem umfangsseitigen Abstrecken und

Figuren 9 bis 14

im vertikalen Längsschnitt verschiedene Umformsituationen beim Kaskadenziehen des Ausgangsrohrs.

The invention is explained below with reference to an embodiment shown in the drawings. Show it:

Figure 1

a schematic side view of a drawing cascade for reducing the diameter of a copper outlet tube;

Figures 2 to 6

each in the vertical schematic longitudinal section five different working positions of a clamping and denting unit and an associated mandrel and ironing unit;

Figure 7

in the side view, partially in vertical longitudinal section, the end portion of the starting tube after thinning;

Figure 8

the representation of Figure 7 after the circumferential stretching and

Figures 9 to 14

in the vertical longitudinal section different forming situations when cascading the original pipe.

When cascading e.g. seamless pipes made of non-ferrous metals, such as in particular copper or copper alloys (press pipes, rolled or longitudinally welded pipes), a method is used in which pull plugs 2, 3, 4 inserted in an outlet pipe 1 interact with pull rings 5, 6, 7 (FIGS. 1 and 9) which each form part of a drawing machine 8, 9, 10 of a drawing cascade 11. In the embodiment of Figure 1, three drawing machines 8, 9, 10 with three drawing rings 5, 6, 7 are provided. In these drawing rings 5, 6, 7, the cross section of the outlet pipe 1 is gradually reduced in accordance with the diameters of the through openings of the drawing rings 5, 6, 7 and the diameter of the drawing plugs 2, 3, 4.

The drawing plugs 2, 3, 4 required to carry out the method are, as can be seen in FIG. 9, introduced loosely, ie freely movably, into a plug chamber 12, which is located at the front end in the direction of passage DR of the outlet pipe 1 between a drawing bar 13 and two, the cross-section of the output tube 1 dimples 14 is located.

A device 15 is used to produce this plug chamber 12, as can be seen in more detail in FIGS. 2 to 6.

This device 15 (see FIG. 2) comprises a clamping and denting unit 16 for the outlet tube 1 and a mandrel and ironing unit 17 which is arranged coaxially with the clamping and denting unit 16 and can be moved relatively to it.

The clamping and denting unit 16 is provided with radially movable clamping jaws 18, which serve for the local fixation of the outlet tube 1. With the jaws 18 brackets 19 are connected, which carry Dellstößel 20 in a diametrical offset, which are radially displaceable in the direction of the output tube 1.

The mandrel and ironing unit 17 comprises two hydraulically actuated cylinders 21, 22, the housings 23, 24 of which are fixed locally and coupled to one another on the end face. The mandrel cylinder 21 which is closer to the clamping and denting unit 16 has a piston rod 25 which can be extended in the direction of the clamping and denting unit 16 and which carries a mandrel 26. The other ironing cylinder 22 has a piston rod 27 which can be extended in the direction of passage DR of the output tube 1. A crossbar 28 is fastened to the free end of the piston rod 27. The cross member 28 is operatively connected via a linkage 29 running parallel to the cylinders 21, 22 to an ironing ring 30 which, in the starting position of the device 15 according to FIG. 2, is located approximately at the free end of the mandrel 26.

To manufacture the plug chamber 12 according to FIG. 9, the outlet pipe 1 with an outer diameter AD of 80 mm and a wall thickness D of 5 mm is first moved so far through the clamping and denting unit 16 that the clamping and Dent unit 16 protrudes a length section 31, which enables the plug chamber 12 and the draw bar 13 to be manufactured. If this position is reached, the output pipe 1 is fixed locally with the help of the clamping jaws 18.

3, the ironing cylinder 22 is now acted upon in the entry direction. In this case, the ironing ring 30 slides along the outer circumference of the end section 31 of the output tube 1 to be formed up to the position lying on the end face of the clamping jaws 18.

4, the mandrel cylinder 21 is acted upon in the extending direction, so that the mandrel 26 penetrates into the approximately 365 mm long end section 31 and, as can be seen in FIG. 7, both the inside diameter ID of 70 mm and the outside diameter AD from 80 mm of the output pipe 1 to the inside diameter ID1 of 72 mm and the outside diameter AD1 of 82 mm.

Thereupon, according to FIG. 5, by acting on the ironing cylinder 22 in the direction of extension, the ironing ring 30 is moved in the direction of travel DR of the output pipe 1, with the mandrel 26 remaining in the end section 31 serving as an abutment, the outer diameter AD1 of the end section 31 as shown in FIG. 8 to the original outer diameter OD reduced by 80 mm. However, the inner diameter ID1, expanded to 72 mm, remains. In addition, the end section 31 has been lengthened from approximately 365 mm to approximately 450 mm due to the stretching from the initial length.

The mandrel and ironing unit 17 is now again in the starting position according to FIG. 6, as shown in FIG. 6. This now allows two diametrically opposite dents 14 (FIG. 9) to be moved by radially inward movement of the Dell tappets 20 according to FIG To produce the outer circumference of the outlet pipe 1, so that herewith also reduces its inner cross section and one of the boundaries of the plug chamber 12 is thereby formed.

Now, in a manner not shown in the drawings, the pull plugs 2, 3, 4 are introduced into the plug chamber 12 and then the draw bar 13 is molded on. The output pipe 1 is thus prepared for a triple pull through the drawing cascade 11.

The pulling process proceeds as follows:

If, according to FIG. 9, the output pipe 1 is moved in the direction of travel DR via the drawing bar 13, the drawing mandrels 3 and 4 move freely through the drawing ring 5, while the output pipe 1 is reduced in its outer and inner diameter, but not in its wall thickness. This is a so-called hollow train.

If, according to FIG. 10, the pull plug 2 reaches the area of the pull ring 5, the dents 14 become effective and cause the pull plug 2 to move into the pull ring 5 up to the pull position. Now the wall thickness of the outlet pipe 1 is also reduced. This situation is illustrated in FIG. 11. It can be seen here that the drawing plugs 3, 4 are still in the area of the plug chamber 12 whose wall thickness has not yet been reduced. Immediately behind the pull plug 3, however, the area of the outlet pipe 1 begins with a reduced wall thickness. Here, two further dents 14 are then also placed at a distance from the drawing plug 3 in order to limit the displacement of the drawing plug 3 in the plug chamber 12 during the following train.

At the next drawing ring 6 (FIG. 12), the outer diameter of the outlet tube 1 is again reduced immediately behind the drawing bar 13, so that the drawing plug 3 is stopped on this drawing ring 6. A hollow pull also takes place here, which corresponds to the distance of the dents 14 from the pulling plug 3. If the drawing plug 3 reaches the drawing position on the drawing ring 6 according to FIG. 12, a further reduction in the wall thickness of the outlet pipe 1 is carried out here.

To continue the cascade pulling, 4 further dents 14 are finally produced in accordance with FIG. 13 at a distance from the smallest pulling plug, these dents 14 then ensuring, according to FIG. 14, that in the area of the pulling ring 7 the pulling plug 4 in cooperation with the pulling ring 7 reduces the reduction the wall thickness to the final dimension.

List of reference symbols

1

- exit pipe

2nd

- pull plug

3rd

- pull plug

4th

- pull plug

5

- drawing ring

6

- drawing ring

7

- drawing ring

8th

- drawing machine

9

- drawing machine

10th

- drawing machine

11

- draw cascade

12th

- plug chamber

13

- Drawbar

14

- dents

15

- Contraption

16

- Clamping and denting unit

17th

- mandrel and ironing unit

18th

- jaws

19th

- brackets

20th

- Dell pestle

21

- cylinder

22

- cylinder

23

- Housing v. 21

24th

- Housing v. 22

25th

- piston rod v. 21

26

- thorn

27

- piston rod v. 22

28

- traverse

29

- linkage

30th

- ironing ring

31

- Longitudinal section v. 1

AD

- outer diameter of 1

AD1

- outer diameter of 31

D

- wall thickness of 1

DR

- Direction of passage

ID

- inner diameter of 1

ID1

- inner diameter of 31

Claims (3)

1. Method for the production of a stopper chamber (12) which accommodates at least two drawing stoppers (2, 3, 4) and is bounded on one side by a drawing tang (13) and on the other side by an indentation (14) made in the external circumference of a starting tube (1) during cascade drawing of tubes (1) made of non-ferrous metals or alloys thereof, characterised in that the end portion (31) of the starting tube (1) lying at the front in the direction of travel (DR) is first expanded enlarging the inside diameter (ID) and the outside diameter (AD), and then the outside diameter (AD1) of the expanded end portion (31) is stretched to the original outside diameter (AD) lengthening this end portion (31), whereupon the indentation (14) is produced, then the drawing stoppers (2, 3, 4) are introduced into the stopper chamber (12) and lastly the drawing tang (13) is formed.
2. Device for implementing the method according to patent claim 1, which exhibits a clamping and indenting unit (16) for the starting tube (1) and an expanding and stretching unit (17) which is disposed coaxial with the clamping and indenting unit (16) and is displaceable relative to it, the clamping and indenting unit (16) being provided with clamping jaws (18) and indenting tools (20) movable radially relative to the starting tube (1), and the expanding and stretching unit (17) being provided with an expander (26) displaceable in the longitudinal axis of the starting tube (1), and with a stretching die (30) displaceable on the circumferential side of the expander (26) and the portion (31) of the length of the starting tube (1) projecting on the front side of the clamping and indenting unit (16).
3. Device according to patent claim 2, characterised in that the expanding and stretching unit (17) exhibits two hydraulically actuated cylinders (21, 22) coupled to one another in the longitudinal axis of the starting tube (1) with piston rods (25, 27) which can be extended in opposite directions, the piston rod (25) which can be extended in the direction of the clamping and indenting unit (16) carrying the expander (26), and the other piston rod (27) being connected to the stretching die (30) by means of a rod assembly (29) parallel with the cylinders (21, 22).

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