Isothermal forging system

Abstract

The invention relates to a system for isothermally forging metal semifinished products close to the final contours within a vacuum and/or a protective gas atmosphere, comprising at least one forging press (1) which comprises at least one press ram (4) that extends into a vacuum forging chamber (3), at least one upper tool (5), and at least one lower tool (6); at least one workpiece changing chamber (9) which is connected to the vacuum forging chamber (3) in a gas-tight manner; and a plurality of lock chambers (11, 12) for preparing and/or heating and/or cooling workpieces, said lock chambers being connected to the workpiece changing chamber (9) in a gas-tight manner, wherein at least the vacuum forging chamber (3) has at least one round cross-sectional contour.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application PCT/EP2022/087911, filed on Dec. 27, 2022, which claims the benefit of German Patent Application DE 10 2022 201 470.7, filed on Feb. 11, 2022.

TECHNICAL FIELD

The disclosure relates to a system for isothermally forging metal semi-finished products close to the final contours within a vacuum and/or protective gas atmosphere with at least one forging press that comprises at least one press ram that extends into a vacuum forging chamber, at least one upper tool and at least one lower tool.

BACKGROUND

Methods and systems for isothermal forging metal semi-finished products close to the final contours within a vacuum are generally known in the prior art. With these methods, which are also known as HIF (hot isothermal forging) methods, titanium or molybdenum materials or so-called superalloys, for example, are forged into shape at high temperatures with low deformation rates under superplastic conditions. Turbine blades, for example, are produced in this manner. Such a production method is known, for example, from U.S. Pat. No. 5,933,951A.

The HIF method is characterized in particular by the fact that both the forging tools and the workpieces are heated in a vacuum to the temperature that allows superplastic deformation of the workpiece prior to the carrying out of the forging process. It is known to preheat the semi-finished products to be formed in a manipulator tunnel before the forging process and to feed the preheated workpiece into a heated vacuum forging chamber.

Known systems for isothermal forging are complex, since it is difficult to reliably achieve the vacuum pressure of less than 0.05 mbar required for the forging process and to maintain low leakage rates. Due to the fact that a long preheating time is required for the workpieces and a long heating time is required for the tools, the cycle times for the production of the individual parts along with the changeover times for the systems in the event of a necessary tool change are long.

SUMMARY

The present application discloses a system of the type mentioned at the beginning that is characterized by low leakage losses. The disclosed system enables short cycle and changeover times when carrying out the method of isothermal forging.

According to one aspect, a system for isothermally forging metal semi-finished products close to the final contours in a vacuum and/or protective gas atmosphere is provided, with at least one forging press that comprises at least one press ram that extends into a vacuum forging chamber, at least one upper tool and at least one lower tool, with at least one workpiece changing chamber that is attached to the vacuum forging chamber in a gas-tight manner and with a plurality of lock chambers for providing and/or heating and/or cooling workpieces that are attached to the workpiece changing chamber in a gas-tight manner, wherein at least the vacuum forging chamber has at least one round cross-sectional contour.

Preferably, the vacuum forging chamber and at least the workpiece changing chamber are designed to be able to be evacuated and are in each case attached to a vacuum source.

“Gas-tight” is to be understood in particular as a tightness that enables the ability to evacuate.

A round cross-sectional contour is particularly favorable with regard to the mechanical load-bearing capacity of the structure when subjected to negative pressure. In addition, the resulting round transitions and ports along with feedthroughs are easier to seal with lower leakage losses.

With the system in accordance with the invention, it can be provided that the vacuum forging chamber has a circular cross-sectional contour and round feedthroughs and round openings.

With the preferred variant of the system in accordance with the invention, the vacuum forging chamber is designed as a substantially cylindrical chamber with round feedthroughs and ports, wherein preferably the transitions to the upper and lower end faces are also rounded. Any maintenance openings provided in the vacuum forging chamber are also preferably circular or oval openings with corresponding closures.

With a particularly advantageous variant of the system in accordance with the invention, the workpiece changing chamber and the lock chambers also have round cross-sections.

The vacuum forging chamber, the workpiece changing chamber and the lock chambers can be connected to one another in a gas-tight manner via round connecting elements and/or feedthroughs. In this manner, a tube-shaped modular system can be provided. Furthermore, a plurality of workpieces can be prepared, heated and fed into the vacuum forging chamber in parallel.

Preferably, at least one tool changing chamber is provided, which is also designed as a tube-shaped component with a circular cross-section. A tool changing chamber, which is attached to the vacuum forging chamber diametrically opposite the workpiece changing chamber, for example, has the advantage that tools for changing over the forging press to other components can be kept preheated in the tool changing chamber. The heating time for a tool can amount to up to 24 hours, for example, such that the design of the system with a tool changing chamber has the advantage that a changeover to other tools can be carried out with little loss of time. Thereby, it can be provided that the tool changing chamber can also have a plurality of lock chambers for feeding in various upper tools and various lower tools within a vacuum. Expediently, the lock chambers of the tool changing chamber can also be designed to be shut off in a gas-tight manner relative to the tool changing chamber by means of correspondingly designed vacuum gate valve.

The lock chambers of the workpiece changing chamber and/or the tool changing chamber can, for example, be closed off from the atmosphere with circular hatches.

The vacuum gate valves are expediently fitted with round slide plates.

With a particularly advantageous variant of the system in accordance with the invention, a plurality of vacuum pumps is provided, which are arranged below a shop floor, preferably in a system sub-floor. Such an arrangement makes it possible to arrange the vacuum pumps in each case directly below the individual chambers of the system, such that the number of vacuum lines required, the length of the vacuum lines and the number of vacuum distributions required can be minimized, which also contributes to the reduction of leakage losses. If the vacuum pumps were arranged above the shop floor, it would be necessary to provide longer line runs, since the lines would have to be laid around the system and the individual chambers could not be attached directly.

At least one vacuum pump can be arranged in each case directly below the vacuum forging chamber and below the workpiece changing chamber and preferably also below the tool changing chamber.

Preferably, the workpiece changing chamber, the lock chambers and preferably also the tool changing chamber are joined together as tube-shaped components in a modular design, such that the system can be expanded by the required number of lock chambers. A plurality of tube-shaped components can be combined to shape a tunnel-shaped workpiece changing chamber, for example. A plurality of tube-shaped components can also be combined to form a tunnel-shaped tool changing chamber. Tube-shaped lock chambers can be attached in each case to both sides of the tool changing chamber and/or the workpiece changing chamber.

At least one horizontally movable manipulator for handling the workpieces is arranged at least in the workpiece changing chamber. A movable manipulator for handling the tools can also be provided in the tool changing chamber.

Expediently, the feedthrough of the press ram into the vacuum forging chamber comprises a water cooling unit.

With a preferred and advantageous embodiment of the system in accordance with the invention, it is provided that the pressure stage of the vacuum forging chamber comprises at least two sealing flanges in the region of the feedthrough of the press ram, which interact internally and circumferentially with a sealing system of the press ram. The flanges are preferably connected to one another via at least one bellows made of stainless steel, preferably via two such bellows.

The invention is explained below by means of an example of an exemplary embodiment with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partial sectional view of a system for isothermally forging metal semifinished products,

FIG. 2 shows a top view of the system,

FIG. 3 shows a schematic perspective view of the system,

FIG. 4 shows a schematic sectional view of the press ram and the upper and lower tools of the forging press,

FIG. 5 shows a perspective sectional view of the vacuum forging chamber and

the tool changing chamber attached to it,

FIG. 6 shows a schematic representation of a lock chamber designed as a heating chamber, and

FIG. 7 shows a perspective representation of a vacuum gate valve.

DETAILED DESCRIPTION

The system shown in FIG. 1 for the isothermal forging of metal semi-finished products comprises a forging press 1 with four columns 2 and a press ram 4 that extends into a vacuum forging chamber 3 with an upper tool 5 (see FIG. 4), which interacts with a lower tool 6 arranged in the vacuum forging chamber 3 for shaping a heated semi-finished product 7. With the system in accordance with the invention, the press ram 4 is hydraulically vertically or axially displaceable, wherein it is sealed in a feedthrough 8 of the vacuum forging chamber 3. The invention is to be understood in such a manner that the press ram can also be mechanically displaceable.

The vacuum forging chamber 3 is connected to a workpiece changing chamber 9, on the one hand, and to a tool changing chamber 10, on the other hand. First lock chambers 11 are attached to the workpiece changing chamber 9, whereas second lock chambers 12 are attached to the tool changing chamber. The vacuum forging chamber 3, the workpiece changing chamber 9 and the tool changing chamber 10 along with the first and second lock chambers 11, 12 can in each case be evacuated and are connected to one another in a gas-tight manner or can be attached to one another. For this purpose, all chambers 3, 9, 10, 11, 12 are attached to vacuum pumps 13, which are arranged below a shop floor 14 under the system in a system sub-floor 15.

Semi-finished products 7 can be fed into the workpiece changing chamber 9 via the first lock chambers 11 and finished forged products can be discharged from the workpiece changing chamber 9. This is accomplished by means of a manipulator 16 that can be moved linearly and substantially horizontally within the workpiece changing chamber 9. The workpiece changing chamber 9 is designed as a tube-shaped tunnel for handling the semi-finished products 7 and the finished products, which has a round, circular cross-section, with which it is attached to a correspondingly designed opening of the vacuum forging chamber 3. The first lock chambers 11 are also designed as tube-shaped components with a round, circular cross-section, with which they are attached to correspondingly designed openings of the workpiece changing chamber 9 at the side of the latter.

The first lock chambers 11 can be closed in a gas-tight manner to the outside against the atmosphere with correspondingly designed round hatches 18 and via vacuum gate valves 23 with respect to the workpiece changing chamber 9. At least some of the first lock chambers 11 are equipped with heating devices 19 for preheating the semi-finished products 7.

A first lock chamber 11 designed as a heating chamber is shown in FIG. 6. This comprises the heating device designated 19 and a hydraulically lowerable hood 20, which encloses the semi-finished product 7 during the heating process in order to accelerate the heating process. The heating device 19 is designed as a heating plate with at least one resistance heating element.

The second lock chambers 12 are designed in a manner corresponding to the first lock chambers 11 and are in each case attached to the side of the tool changing chamber 10. The tool changing chamber 10 is also attached as a tube-shaped component with a circular cross-section to a correspondingly designed opening of the vacuum forging chamber 3. The vacuum forging chamber 3 can be shut off with respect to both the workpiece changing chamber 9 and the tool changing chamber 10 in each case by means of a vacuum gate valve 23. Tools, upper tools 5 on the one hand and lower tools 6 on the other hand, can be introduced into and discharged from the tool changing chamber 10 through the second lock chambers 12. A horizontally movable lifting carriage 17 is preferably provided in the tool changing chamber 10 for this purpose. With the lifting carriage 17, the tools are moved into the vacuum forging chamber 3, where they are coupled to the press ram 4 by a corresponding lifting movement of the latter.

The vacuum forging chamber 3 has a circular cross-section, as can be seen in particular from the representation in FIG. 5, and is designed as an approximately cylindrical housing. The transitions of the cylindrical wall of the vacuum forging chamber 3 into the upper and lower end faces can be rounded. In this respect, the representation in FIG. 5 is simplified and this detail is not visible in FIG. 5. For reasons of simplification, parts of the front columns 2 of the forging press 1 are also not shown in FIG. 5.

As can be seen from the representation in FIG. 5, the vacuum gate valves 23 comprise circular slide plates 24, which are shown closed in FIG. 5. An upper tool 5 and a lower tool 6 can be inserted into and removed from the tool changing chamber 10 on each side of the tool changing chamber 10 via the second lock chambers 12, which can also be closed with hatches 18. With the variant of the system shown in FIG. 5, in each case two second lock chambers 12 are attached to the tool changing chamber 10. In accordance with the invention, it can be provided to extend the tool changing chamber 10 by correspondingly designed tube-shaped components, to which further second lock chambers 12 are then attached, such that a plurality of tools can be preheated in a standby position. A corresponding modular structure is provided for the workpiece changing chamber 9 and the first lock chambers 11 attached to it.

As can be seen from the representation in FIG. 3, the workpiece changing chamber 9 and the tool changing chamber 10 are in each case provided with end openings, which can also be closed with hatches 18. In addition, the vacuum forging chamber 3 is provided with a maintenance opening 21, which is closed by a maintenance door 22. The maintenance opening 21 and the maintenance door 22 are also designed to be round, since such contours can be sealed more easily and with less force.

With the forging method, it is provided that the semi-finished products 7 are initially introduced into one or more of the first lock chambers 11 by means of a manipulator, lifting carriage or the like. If the lock chamber 11 in question is opened, it is sealed in a gas-tight manner with respect to the workpiece changing chamber 9 by means of a vacuum gate valve 23. The first lock chamber 11 is subsequently closed and, after corresponding evacuation and preheating of the semi-finished product 7, is connected to the workpiece changing chamber 9 by means of a heating device 19 by actuating the vacuum gate valve 23. The heated semi-finished product 7 is then picked up by the manipulator 16 and placed in the lower tool 6 of the forging press 1, as shown in FIG. 4. For the purpose of shaping the forged part, the upper tool 5 and the lower tool 6 are closed by actuating the press ram 4. After completion of the forged part, it is in turn removed by the manipulator 16 and placed in a first lock chamber 11 for the purpose of cooling and subsequent removal.

LIST OF REFERENCE SIGNS

• • 1 Forging press
  • 2 Columns
  • 3 Vacuum forging chamber
  • 4 Press ram
  • 5 Upper tool
  • 6 Lower tool
  • 7 Semi-finished products
  • 8 Feedthrough
  • 9 Workpiece changing chamber
  • 10 Tool changing chamber
  • 11 First lock chambers
  • 12 Second lock chambers
  • 13 Vacuum pumps
  • 14 Shop floor
  • 15 System sub-floor
  • 16 Manipulator
  • 17 Lifting carriage
  • 18 Hatches
  • 19 Heating device
  • 20 Hood
  • 21 Maintenance opening
  • 22 Maintenance door
  • 23 Vacuum gate valve
  • 24 Slide plate

Claims

1.-13. (canceled)

14. A system for isothermally forging metal semi-finished products close to final contours within a vacuum and/or protective gas atmosphere, comprising:

a forging press (1), including a press ram (4) that extends into a vacuum forging chamber (3), the vacuum forging chamber (3) having a round cross-sectional contour;

an upper tool (5);

a lower tool (6);

a workpiece changing chamber (9), the workpiece changing chamber (9) being connected to the vacuum forging chamber (3) in a gas-tight manner;

a plurality of lock chambers (11, 12) for preparing and/or heating and/or cooling workpieces, the lock chambers being connected to the workpiece changing chamber (9) in a gas-tight manner; and

a tool changing chamber (10) that is attached to the vacuum forging chamber (3).

15. The system according to claim 14,

wherein the vacuum forging chamber (3) is a substantially cylindrical chamber with round feedthroughs and ports.

16. The system according to claim 14,

wherein the workpiece changing chamber (9) and the lock chambers (11, 12) have round cross-sections.

17. The system according to claim 14,

wherein the vacuum forging chamber (3), the workpiece changing chamber (9), and the lock chambers (11, 12) are connected to one another in a gas-tight manner via round feedthroughs.

18. The system according to claim 14,

wherein the tool changing chamber (10) is a tube-shaped component having a round cross-section.

19. The system according to claim 14,

wherein further lock chambers (12) are attached to the tool changing chamber (10) via vacuum gate valves (23).

20. The system according to claim 19,

wherein the vacuum gate valves (23) have round slide plates (24).

21. The system according to claim 14,

further comprising a plurality of vacuum pumps (13),

the vacuum pumps (13) being arranged below a shop floor (14) in a system sub-floor (15).

22. The system according to claim 14, further comprising

a vacuum pump (13) arranged below the vacuum forging chamber (3), and

a further vacuum pump (13) arranged below the workpiece changing chamber (9).

23. The system according to claim 14,

wherein at least one vacuum pump (13) each is arranged below the vacuum forging chamber (3), below the workpiece changing chamber (9), and below the tool changing chamber (10).

24. The system according to claim 14,

wherein the workpiece changing chamber (9), the lock chambers (11, 12), and the tool changing chamber (10) are joined together as tube-shaped components in a modular design.

25. The system according to claim 14,

wherein at least some of the lock chambers (11, 12) have a heating device (19) for heating workpieces or a tool.

26. The system according to claim 14, further comprising

a horizontally movable manipulator (16) for handling workpieces arranged in the workpiece changing chamber (9).