WO1992013656A1

WO1992013656A1 - Device for the hydrostatic shaping of hollow bodies of cold-workable metal

Info

Publication number: WO1992013656A1
Application number: PCT/DE1992/000064
Authority: WO
Inventors: Wilhelm Kaiser
Original assignee: Hde Metallwerk Gmbh
Priority date: 1991-02-01
Filing date: 1992-01-31
Publication date: 1992-08-20
Also published as: DE4103078A1; DE4103078C2

Abstract

A device for the hydrostatic shaping of hollow bodies (16) of cold-workable metal within a shaping recess of a die (13) is fitted with at least one system for supplying pressurising fluid into the hollow body (16). The supply system consists of a supply sleeve coupling (22) conveying the pressurising fluid which can be pushed over the front of a cylindrical clamping region (17) of the hollow body (16) located outside the shaping recess of the die (13) so as to be fluid and pressure-tight. In the supply position, the supply sleeve coupling (22) can be releasably clamped in relation to the die (12) and accepts the clamping region (17) so as to be axially movable in relation thereto. Between the supply sleeve coupling (22) and a high-pressure generator (23) is fitted the line for the pressurising fluid in the form of a pipe (24), e.g. a steel pipe or the like. The pipe (24) forms a curved section (28-29) which permits movement of the supply sleeve coupling (22) and/or the die (13) by bending flexibly.

Description

Device for the hydrostatic shaping of hollow bodies made of cold-formable metal

The invention relates to a device for the hydrostatic forming of hollow bodies made of cold-formable metal within a mold cavity of a die with at least one feed for the hydraulic fluid into the hollow body.

With the above-mentioned known device (see Industrial Indicator No. 20 from 9.3.1984 / 106, p. 16 and 17) tubular hollow parts made of cold-formable metal, e.g. made of 16 MnCr 5, deformed by supplying high, hydrostatically generated internal pressure. In addition to the high hydrostatic internal pressure, there is an additional axial pressure which acts on the pipe end faces. That axial pressure and the simultaneous effect of the internal pressure have the consequence that the hollow body wall bears against the engraving of the mold or the die.

In practice, this is such that a straight tube is inserted into the mold parting plane between the upper and lower dies and the die is fed. Between the upper and lower dies, however, there remains sufficient space for two diametrically opposed, horizontally arranged press rams, the free end faces of which accommodate the pipe section to be deformed, which is aligned with the press rams. The forming is then carried out by introducing hydraulic fluid into the interior of the tube while simultaneously End of the axial pressure, the two rams are moved towards each other.

With the known hydrostatic reshaping, molded parts with a uniform shape over the circumference, molded parts with sectoral reshaping and finally uniform and sectoral reshaping, merging molded parts can be produced.

The advantage of hollow parts produced in this way is, on the one hand, that - e.g. in permanent mold casting - undercut internal cavities can be produced, which can either not be machined or only be manufactured with complicated tools (e.g. by spark erosion). In addition, the known hollow parts - in contrast to the hollow parts produced by machining - are relatively light and, as a result of the strain hardening associated with the forming, are very resistant with a favorable fiber course, which is similar to that of a forged fiber.

In the meantime, the known hydroforming is perceived as disadvantageous because the hollow body wall cannot fall below a certain minimum thickness. This is essentially due to the fact that the tubular body to be deformed must be designed to be dimensionally stable in order to accommodate the relatively high axial pressure acting on its end faces, which can only be achieved by means of a sufficient wall thickness. In addition, the known internal high-pressure forming is always limited to parts in which the force-effect lines for introducing the axial forces, that is to say the ram and the longitudinal center axis of the tube, exactly coincide. In this way, at most lateral sectoral protuberances can be produced for the production of cross pieces or T pieces, for example. Here, the longitudinal axis of the protuberance, which is produced sectorally in accordance with the die engraving, runs transversely to the force line of the press ram and the tube (see "Industrial Indicator" loc. Cit., P. 4 and 8).

With the known hydroforming, a certain number of shapes can already be created, but this is always tied to the general condition of a common force line of action of the press ram and the pipe to be deformed, that is to say to a basically straight basic shape.

Finally, the known device (see "Industrial Indicator" cited above) is perceived as disadvantageous because of its rigidity, which is caused in particular by the press rams for the introduction of axial force and which also has an effect on handling.

On the basis of the known device (see "Industrial indicator" loc. Cit.) Described at the outset, the invention is based on the object of designing the known device in such a way that it is easier to handle with a considerably simplified design. Exercise permitted for both interior work and production.

According to the invention, this object is achieved in that the feed forms a feed sleeve which guides the pressure fluid and which can be pushed onto a cylindrical holding region of the hollow body outside the mold cavity of the hollow body in a liquid-tight and pressure-tight manner, the feed sleeve is releasably lockable in its feed position with respect to the die and receives the holding area in the axial direction relative to it, and a pipe, such as steel pipe or the like, is located between the feed sleeve and a high-pressure generator as a line for the pressure fluid. is arranged, which represents a bending path, which absorbs movements of the feed sleeve and / or the die with an elastic bend.

The device according to the invention can dispense with special press punches for introducing an axial pressure acting on the hollow body to be reformed. Rather, in the device according to the invention, the pressure fluid alone ensures the deformation of the hollow body within the die. A decisive prerequisite for this is that the feed sleeve to be pushed onto the cylindrical holding area of the hollow body in a liquid-tight and pressure-tight manner, in its axially fixed feeding position, receives this holding area in the axial direction relative to it. This can result in the action of the hydrostatic internal pressure to a certain extent, material is drawn from the holding area.

The elimination of the press punches required in the prior art (see “Industrial Indicator” cited above) alone gives greater flexibility in the handling of the device according to the invention.

The device according to the invention generally works with a hydrostatic internal pressure of at least 800-1500 bar acting on the hollow body to be formed. Depending on the material used and the design of the article to be achieved, it may also be necessary to reduce the internal hydrostatic pressure to 3000 Increase bar and more. Such high pressures require particularly safe measures just with regard to their supply routes. A safe and at the same time adaptable feed path has been achieved by the invention that a pipe, such as a steel pipe or the like, is arranged between the feed sleeve and the high-pressure generator as a line for the pressure fluid, which represents a bending path, which movements of the feed sleeve and / or the die with an elastic bend.

Those features of the invention offer particular advantages:

The otherwise rigid pipeline, which is designed as a bending section, is able, for example, to accommodate a reciprocating drive movement of the feed sleeve. In addition, the die and any feed sleeve assigned to it can be manipulated in practically any manner when setting up the device according to the invention, without having to take particular account of the course of the high-pressure line. This results in an additional spatial movement unit, for example in the event that the arrangement according to the invention has to be placed in a specific spatial relationship with a manipulator for the workpiece feed and the workpiece removal.

It is important that the bending path of the steel tube is designed in such a way that plastic deformation can never occur. This can mean that the pipeline represents a relatively long, wide span between the high pressure generator and the connection to the feed sleeve. Of course, such a bending section can be curved, cranked or the like in one plane or in space. be trained.

In a further embodiment of the invention, the feed sleeve can be driven back and forth relative to the hollow body accommodated in the die, which, as already mentioned, is of particular importance in connection with the flexible pipe.

Furthermore, the invention provides that a guide means for the feed sleeve which can be moved back and forth is fastened exclusively to the die by means of a holder, the feed sleeve being releasably locked to the holder via the guide means. It is conceivable that during the forming work in the infeed position of the infeed sleeve, owing to the high hydrostatic internal pressure, a considerable reaction force acts axially away from the die on the infeed sleeve. Such forces can be passed on to the die via the holder, which advantageously means a closed "flow of force in a small way.

In this connection, an embodiment of the invention consists in that part of a drive for the back and forth movement of the feed sleeve also forms its guide means, while another part of the drive is fastened to the holder and, together with the latter, a rigid power transmission bridge to the die forms.

In practical terms, those features of the invention can mean that the drive consists of a piston-cylinder unit operated by pressure medium, that the part of the drive which carries the feed sleeve is the piston rod, while the other part of the drive is the cylinder on the holder is attached.

A particularly easy-to-use device according to the invention has been achieved in that the die, feed sleeve and its drive for the back and forth movement form a unitary, spatially manageable assembly which is operated on an operating device for generating an opening and Closing movement of the die, such as on the table of a tool press, is to be releasably attached.

In this connection, too, the flexible pipeline offers particular advantages in the event that the pressure generating system would have to be converted for operational reasons, which is facilitated by the fact that the high-pressure generator and possibly also an associated filling pressure generator can be easily moved. bar, such as are movable, are formed.

Preferred exemplary embodiments according to the invention are shown in more detail in the drawings, in which:

1 is a more schematic side view of the device according to the invention,

2 is a partially horizontally sectioned plan view, approximately corresponding to the section line designated II-II in FIG. 1,

3 shows a cross section through a steel pipeline between the feed sleeve and the high-pressure generator according to the section line III-III entered in FIG. 2 and

4 and 5 two further arrangement examples with other dies, with which the spatial adaptability of the device is to be demonstrated. In the drawings, a device for the hydrostatic shaping of hollow bodies made of cold-formable metal, irrespective of its individual configuration, is generally designated by the reference number 10.

A die 13 is arranged on a press table 11 of a tool press 12.

The die 13 consists of an upper die 14 and a lower die 15 which, in the region of their parting plane E, has a tubular workpiece 16 (hollow body) in a mold cavity (not shown), e.g. made of steel. Of the hollow body 16, only the holding areas 17 protruding from the die 13 at both ends are visible.

The upper die 14 is releasably attached to a press upper part 18 which can be moved up and down along the movement arrow y.

A hydraulic piston-cylinder unit 19 (hydraulic cylinder) with one cylinder 20 and one piston rod 21 is arranged on each side of the device. At the free end of each piston rod 21, a feed sleeve 22 is fastened, which serves to supply pressure fluid from a high-pressure generator 23, which is shown schematically on the right in FIG. 1.

Together with the piston rod 21, the feed sleeve 22 can be moved back and forth along the movement arrow denoted by x. For hydrostatic shaping of the hollow body 16, both hydraulic cylinders 19 are actuated in such a way that the two piston rods 21, together with the feed sleeves 22 carried by them, extend out of the cylinder 20 in the direction of the die 13. In this case, the feed sleeves 22 slide pressure-tight and liquid-tight over the two holding areas 17 on the hollow body side.

Then, from the high-pressure generator 23, pressure fluid is introduced into the hollow body 16 to be formed via the feed sleeve 22 shown on the left in FIG. 1 or in FIG. 2 via a high-pressure line 24. Here, a hydrostatic internal pressure of, for example, 1500 bar builds up within the forming area of the hollow body 16 arranged in the die 13, which presses the hollow body wall against the engraving of the die-side mold cavity. During the forming, the feed sleeves 22 and the piston rods 21 are blocked in the axial direction.

Finally, the high pressure is switched off, so that the two feed sleeves 22 can return to their starting position away from the die 13 (see, for example, FIGS. 1 and 2). After opening the die 13 by lifting the upper press part 18 together with the upper die 14, the completely formed hollow body 16 can be removed, for example by means of a manipulator, which can also load the die 13 with hollow body blanks 16. In each case on the front cylinder cover 34 of the hydraulic cylinder 19, two rigid tabs 25, which are arranged parallel to one another, are fastened, which are also fastened to the lower die 15. The die 13 therefore forms, thanks to the link bridge 25, 25, together with the hydraulic cylinders 19, a cohesive, closed assembly which manipulates in almost any desired manner in a simple, desired manner, in particular in a specific position on the press table 11 and below the upper press part 18 can be adjusted.

The above-mentioned high hydrostatic internal pressure of 1500 bar, which can be up to 3000 bar and more depending on the material and article, causes a reaction force directed away from the die 13, which must be absorbed by the hydraulic cylinders 19. This is because these are hydraulically blocked during the forming process, so that the two feed sleeves 22 are releasably locked in the axial direction x with respect to the die 13. The two bracket bridges 25, 25 each form a rigid power transmission bridge to the die 13 and hereby advantageously bring about a closed force connection over a short distance.

The high-pressure generator 23 is preceded by a filling pressure generator 26, which initially causes the hollow body 16 to be quickly filled with pressure fluid at a filling pressure of approximately 65-80 bar with a relatively large delivery volume via the high-pressure head 27 and the high-pressure line 24. During this phase, the feed sleeves 22 are of course - as already described above - on the holding areas 17 of the hollow body 16, which is open at both ends, is pushed on in a liquid-tight and pressure-tight manner.

The pressure fluid passes from the high-pressure generator 23 via its line connection 28, the high-pressure line 24 to the line connection 29 on the piston rod 21, which contains a liquid-conducting channel 30, which is only shown in dashed lines in FIG. 2 and which passes through a channel 31 the respective feed sleeve 22 is continued.

The two connections 28-29 also stand for a bending distance of the steel tube 24, which in the present case extends in a flat, long curve approximately in one plane. The steel tube 24 is so long that a back and forth movement of the piston rod 21 carrying the feed sleeve 22 always remains in the flexurally elastic range, so that practically an innumerable large number of working cycles with regard to the known Wöhler curve is possible.

Characterized in that the steel pipe 24 as elastic

Bending path is formed, an arrangement and

Adjustment of the die 13 together with the hydraulic cylinders 19 practically regardless of the spatial

Position of the high pressure generator 23 are made.

On the other hand, the high-pressure generator 23 (just like the filling pressure generator 26) can be moved on rollers 32. In this way, the high-pressure generator 23 and the filling pressure generator 26, thanks to the flexible design of the steel tube 24, have a very large scope be moved if the operating situation should require this.

From Fig. 3 it can be seen that the steel tube 24 is very thick-walled for the transmission of the hydraulic fluid. In the present exemplary embodiment, the inside diameter a is 4.8 mm, while the tube wall thickness b is 4.7 mm.

4 and 5, it should only be shown that the high-pressure steel pipeline 24, which represents a flexible bending section 28-29, allows practically any configuration and arrangement of dies 13. For example, the die according to FIG. 5 is provided with a corresponding mold cavity (not shown) for reshaping a hollow body 16 extending at a right angle, so that the longitudinal axes of the two hydraulic cylinders 19, which are aligned with the holding areas 17 on the hollow body side, are also aligned , extend at right angles to each other. 5 an approximately 135 ° arrangement is provided.

A tool press which has only three support columns 33 arranged at a circumferential angular distance of 120 ° has proven to be favorable for the unhindered spatial handling of the assemblies formed in each case from the two hydraulic cylinders 19 with feed sleeves 22 and from the die 13.

In addition, it should be noted that in the exemplary embodiments shown, only one feed sleeve 23 is always connected to the high-pressure line 24, rend the other feed sleeve 22 has no liquid passage, ie forms a blind sleeve 22, which in an otherwise identical design with respect to the hydraulic fluid feed sleeve 22 only has a locking function.

The filling line (hose) between _. High-pressure generator 23 and filling pressure generator 26 are designated by 35.

Claims

Expectations

1. Device for the hydrostatic forming of hollow bodies made of cold-formable metal within a mold cavity of a die, with at least one feed for the hydraulic fluid in the hollow body, characterized in that the feed forms a feed sleeve (22) guiding the hydraulic fluid, which on a cylindrical holding region (17) of the hollow body (16) located outside the mold cavity of the die (13) can be pushed on in a liquid-tight and pressure-tight manner, the feed sleeve (22) being releasably closed in its feed position with respect to the die (13) is to lock and holds the holding area (17) in the axial direction relative to it, and a pipe (24), such as steel pipe or the like, between the feed sleeve (22) and a high-pressure generator (23) as a line for the pressure fluid. is arranged, which represents a bending section (28-29), which movements of the feed sleeve (22) and / or the die s (13) with elastic bend.

2. Device according to claim 1, characterized gekenn¬ characterized in that the feed sleeve (22) relative to the in the die (13) accommodated hollow body (16) can be driven back and forth.

3. Apparatus according to claim 2, characterized gekenn¬ characterized in that a guide means (21) for the reciprocating feed sleeve (22) by means of a shark Terung (25, 25) is exclusively attached to the die (13).

4. Device according to one of the preceding claims, characterized in that the Einspeisungs¬ sleeve (22) via the guide means (21) with respect to the holder (25, 25) is releasably locked.

5. Device according to one of the preceding claims, characterized in that a part (21) ei¬ Nes drive (19) for the reciprocating movement of the Ein¬ feeding sleeve (22) at the same time forms its guide means, while another Part (20 at 34) of the drive (19) is fastened to the holder (25, 25) and, together with the latter, forms a rigid power transmission bridge to the die (13).

6. The device according to claim 5, characterized gekenn¬ characterized in that the drive consists of a pressure medium-operated piston-cylinder unit (19) that the feed sleeve (22) carrying part of the drive (19) is the piston rod (21) , while as another part of the drive (19) the cylinder (20 at 34) is attached to the holder (25, 25).

, Device according to one of the preceding claims, characterized in that the die (13), feed sleeve (22) and their drive (19) for the reciprocating movement form a unitary, spatially manageable assembly which operates on an operator ¬ device for generating an opening and closing movement (y) of the die (13 at 14), such as on the table (11) of a tool press (12), is releasably attached.

8. Device according to one of the preceding claims, characterized in that the high-pressure generator (23) and optionally also a fill pressure generator (26) associated therewith easily displaceable, such as e.g. are movable, are formed.