Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
  • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
  • B21D26/033—Deforming tubular bodies
  • B21D26/043—Means for controlling the axial pusher

Definitions

• 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.
• tubular hollow parts made of cold-formable metal e.g. made of 16 MnCr 5
• tubular hollow parts made of cold-formable metal e.g. made of 16 MnCr 5
• 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.
• 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).
• 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.
• the known hydroforming is perceived as disadvantageous because the hollow body wall cannot fall below a certain minimum thickness.
• 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.
• 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.
• 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).
• 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.
• 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
• 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 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.
• 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.
• 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.
• 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.
• a bending section can be curved, cranked or the like in one plane or in space. be trained.
• 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.
• 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.
• 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.
• 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 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.
• 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.
• FIG. 2 is a partially horizontally sectioned plan view, approximately corresponding to the section line designated II-II in FIG. 1,
• FIG. 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
• a device for the hydrostatic shaping of hollow bodies made of cold-formable metal 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.
• 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.
• 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.
• 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.
• 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.
• the feed sleeves 22 and the piston rods 21 are blocked in the axial direction.
• 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).
• 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.
• a manipulator which can also load the die 13 with hollow body blanks 16.
• 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.
• 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.
• Bending path is formed, an arrangement and
• the high-pressure generator 23 (just like the filling pressure generator 26) can be moved on rollers 32.
• 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.
• the steel tube 24 is very thick-walled for the transmission of the hydraulic fluid.
• the inside diameter a is 4.8 mm
• the tube wall thickness b is 4.7 mm.
• the high-pressure steel pipeline 24, which represents a flexible bending section 28-29 allows practically any configuration and arrangement of dies 13.
• 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.
• the filling line (hose) between . High-pressure generator 23 and filling pressure generator 26 are designated by 35.

Landscapes

• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)
• Press Drives And Press Lines (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6424199

Family Applications (1)

Country Status (2)

Cited By (1)

Families Citing this family (4)

Citations (3)

Family Cites Families (2)

• 1991
  • 1991-02-01 DE DE19914103078 patent/DE4103078A1/de active Granted
• 1992
  • 1992-01-31 WO PCT/DE1992/000064 patent/WO1992013656A1/de unknown

Patent Citations (3)

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