EP3015183A1 - Forming press and method for forming a sheet-shaped blank made of metal and having two parts which can be moved together - Google Patents

Abstract

The invention relates to a forming press (1) for forming a sheet-like blank (26) made of metal with at least two mutually movable thermally insulated frame parts (6, 7), wherein a first frame part (6) a die (8) with a negative engraving (10), and wherein the other second frame part (7) in a space (16) of this frame part movable punch (12), wherein the sheet-like blank (26) above the punch (12) to form a pressure chamber (24) with the punch (12) on the stamp (12) receiving the second frame part (7) rests sealingly, wherein the pressure chamber (24) with a pressurized gas from a pressure generator (30) can be acted upon.

Description

The invention relates to a forming press for forming a sheet-like blank made of metal with at least two mutually movable thermally insulated frame parts, wherein a first frame part has a die with a negative engraving, and wherein the other second frame part has a movable in a space of this frame part stamp , wherein the sheet-like blank rests above the punch to form a pressure chamber with the punch on the stamp receiving frame part.

The invention also relates to a forming process.

Under sheet blanks in particular sheets, boards and films are understood.

A forming press for forming a sheet-like blank made of metal is known from the prior art according to DE 10 2012 106 299 A1 known. In this case, a pressure-tight housing is provided in detail, wherein two frame parts are arranged in the housing, wherein the one upper frame part to the other lower frame part is zuverfahrbar. The one upper frame part has a movable in a cylindrical space of the frame part stamp on which has a positive engraving, whereas on the other lower frame part a die with a correspondingly complementary negative engraving is arranged. The method for forming the sheet-like blank made of metal is that the first gas-based deformation of this blank is made to then in a second step, so if the transformation has already taken place substantially, a mechanical final formation of the sheet blank at the sections of Matrize takes place, which are characterized by small radii. Because according to the teachings of the prior art, it is such that relatively large degrees of deformation can be achieved relatively easily and quickly with the gas pressure forming, but the formation of small radii at equally high degrees of deformation requires a disproportionately high pressure on the blank, which is such a one-step process when small radii need to be reshaped, making them uneconomic. The forming of the sheet-like metallic blank is carried out according to the prior art by generating a gas pressure by the stroke of the punch or the frame parts to each other. Furthermore, this reference also teaches to provide higher pressures for forming by increasing the temperature. However, it is also taught to reduce the Compression travel and / or to increase the final pressure the pressure chamber after sealing, but even before the start of the actual compression stroke to charge by gas pressure, which has been generated during the previous press stroke. The pressurized gas may have been cached in a pressure vessel. In summary, this means that the teaching of the prior art amounts to using the pressure generated by the travel of the punch or by the travel of the two frame parts for the forming, where appropriate, before the actual transformation in a pressure vessel cached compressed air for Increasing the pressure in the room above the stamp is used.

To generate the required pressure, if gas is used as a pressure medium, considerable travels required, which means that the cycle times are relatively long. Since not only the stamp is to be used to generate pressure, but also serve the two frame parts of increasing the pressure in the stamp space, it is necessary that the frame parts of the press, so the frame top and frame base are hermetically sealed to the environment. For this purpose, as is clear from the drawings of DE 10 2012 106 299 A1 results, a separate housing provided. Undoubtedly, this requires considerable design and manufacturing effort, which makes such a device, and in particular the tool part relatively expensive.

The object underlying the invention is therefore to provide a cheaper solution for the forming of a sheet-like blank made of metal.

To solve the problem, the invention proposes the pressure chamber with a pressurized gas from a

Pressurize the pressure generator. Such a pressure generator, a compressor, for. As a compressor, which is able to provide the required for the conversion of sheet-like blanks pressures of up to 60 bar and more.

Advantageous features and embodiments of the invention will become apparent from the dependent claims.

Advantageously, the volume of air generated by the pressure generator as a function of the current pressure in the pressure chamber is regulated or controlled. This means that at the beginning of the deformation, the pressure can be relatively low, and only at the final formation, ie when the blank is to invest in small radii at high degrees of deformation, this is done by a corresponding increase in pressure. That is, it is possible via a control or regulation, the specification of a pressure profile, which is closely adapted to the corresponding degrees of deformation.

Furthermore, it is provided in particular that the punch can have a positive engraving that is at least partially complementary to the negative engraving of the die. This ensures that after a gas pressure forming advantageously mechanical, so ultimately by the engraving, sections with small radii can be formed relatively quickly endausge. The method is insofar then formed in two stages.

The stamp is pressure-tight in the space of the other second frame part slidably guided. In order to accomplish the pressure-tightness, a radially encircling piston seal is provided, for example at least one piston ring. This ensures that the gas pressure remains stable over a longer period, and insofar as the gas pressure can act on the blank for a long time.

By using piston rings as a puncture seal small precision errors, which can arise as a result of heating, can be compensated. It is also conceivable to store the frame parts floating, in order to compensate for precision errors during operation can.

According to a further feature of the invention, the die of a first frame part and / or the punch of the other frame part in each case at least one temperature control, which is controllable or regulated. By means of the tempering device, it is made possible to heat the sheet-like blank made of heat-transformable material, in particular of metal, to the forming temperature which is preferably above about 300 ° C. for hot-formable materials, in particular metal, wherein the blank may also already be preheated externally can. The external preheating of the blank ensures short cycle times. Optionally, the heating of the sheet-like blank depending on the metal to be formed z. As a ferritic stainless steel up to about 1,100 ° C. Basically, all possible combinations of the heating of the frame parts, the die, the punch and finally the blank are conceivable. Now it should be noted that the prior art according to the DE 10 2012 106 299 A1 It is not allowed to make a transformation at such high temperatures. This is due to the fact that the stamp is displaceable in the upper part of the frame, but it is to be expected that the stamp on heating the stamp to temperatures of about 300 ° C, in individual cases to temperatures of up to 1,100 ° C, can no longer be moved in the upper frame part, because the frame part due to the outer surface has a high heat radiation, and this should make it difficult to keep the frame part or both frame parts with respect to an equal temperature expansion at the corresponding temperatures or to cool if there are frame parts and stamps made of materials that have at least similar coefficients of thermal expansion exhibit. Therefore, as has already been explained, it is also provided that the stamp is sealed by at least one radially encircling piston seal, in particular at least for round punches by at least one, preferably a plurality of piston rings relative to the space in the frame part. In this respect, there is also the possibility of temperature control to higher temperatures. Furthermore, the seal opened by the piston seal and the relatively small volume pressure chamber the ability to use noble gases economically, z. B. in the transformation of magnesium alloys.

Thus, it is provided in particular in the arrangement of a plurality of tempering that the tempering individually controlled and regulated to possibly nachfahren a predetermined temperature profile can, the temperature profile can be dependent on the desired degrees of deformation at the corresponding points of the sheet-like blank. Specifically, it is provided in relation to the arrangement of the tempering, that the die of a first frame part in the region of the support on the other second frame part has a tempering device, wherein corresponding to the other second frame part in the region of the support for the sheet-like blank also a tempering can have. Advantageously, furthermore, the bottom of the die has a tempering device. That is, by such a tempering, also in the form of a heater, there is the possibility of heating the die as a whole. The stamp also advantageously has a tempering device in the form of a heater in the region of the upper side of the stamp. From this it is clear that not only the punch and the die are centrally heated, but also that the edge region of both the punch and the die, ie the areas where the two frame parts collide and finally for the fixation and sealing of the sheet-like blank ensure, are tempered, so in particular heated to accomplish just in this part by a preselectable temperature profile a tracking of the material, especially at tight radii with correspondingly high degrees of deformation.

In particular, it is further provided that the starting position of the punch in the particular cylindrical space of the other second frame part is such that the punch is located with or without engraving directly in front of the blank sheet, but without deforming it in the starting position. This means that in the case of a stamp with an engraving, the engraving may abut the flat blank at its highest elevation; in the case of a stamp without engraving, ie if the forming is to take place only via the corresponding air or gas pressure, this stamp with a minimum Distance or slightly adjacent is located in front of or on the sheet-like blank. This is to ensure that the pressure can form over the entire surface of the blank and the blank is not scratched or damaged. However, this also means that hereby the pressure space between the top or surface of the punch to the bottom of the blank can be kept relatively small. This has the advantage that the pressure generator only has to generate a low volume flow at the appropriate pressure in order to be able to realize relatively short cycle times. Moreover, it is advantageous that with a small pressure chamber, the cooling of the blank and the tools such as punch and die due to the gas supplied by the pressure generator is low, so that the tempering for heating the sheet-like blank made of metal have only a low energy consumption. This also process interruptions are avoided because of too cool tools.

However, it is also possible to close the frame parts first with a closing force that allows a mechanical forming of the blank, wherein the material of the blank can be easily pulled from the outside into the engraving of the die. After increasing the closing force and the associated sealing, the gas pressure is then built up for forming.

According to a further feature of the invention, the space below the punch communicates with the space formed by the engraving of the die through a compensation line. In other words, this prevents the deformation-damaging increase in the pressure on the die-facing side of the blank, in particular during the final shaping.

It is advantageously provided in this context, when the compensation line is in communication with a pressure generator to generate an overpressure between the die and blank to eject the finished workpiece controlled by the pressure in the space between the die and the tool. In the case of the sealed space below the punch, the formed workpiece can be automatically pushed out of the die due to the punch back movement while simultaneously opening the tools. In this case, an externally controllable compressed air management with all combinations can be provided.

The invention likewise relates to a method for forming a sheet-like blank in a forming press as it is the subject matter of the preceding statements. The process is characterized by several steps, which are described in detail as follows. First, the sheet-like blank, especially in the preheated state is placed on the other second frame part. Then the frame parts are closed, so that the sheet-like blank between the Rack parts is kept sealed. Then the stamp is approached to the sheet-like blank to form the pressure chamber. In this case, however, it is ensured that the blank is not deformed by the engraving of the stamp, provided that the stamp has an engraving. Then, the heating of the sheet-like blank takes place on a specific with respect to the material of the sheet blank forming temperature. The desired forming temperature can be, for example, between 300 ° and 1100 ° C for light metals as well as certain copper alloys and 700 ° to 1100 ° C for steel-like alloys as well as copper alloys and titanium alloys depending on the material to be formed. The blank can already be preheated introduced into the press, which significantly reduces the cycle times. After the frame parts have been moved towards each other, and thus the pressure chamber, which is formed by the sheet-like blank on the one hand and the punch in the cylindrical space of the frame base, is sealed, the pressure space thus formed with a pressurized gas, which is selected depending on the alloy is charged. The closing of the racks can be done in different ways; once, as shown in the drawings, from bottom to top, that is, the frame base is moved simultaneously including stamp up or the frame base is fixed and the frame top is to move down on the frame base. The position of the die in the frame top has the advantage that the component can be removed more easily after forming. After the gas deformation, wherein the gas pressure can act on the blank for a long time, first the gas pressure between the formed component and the stamp is discharged and then moved apart the two frame parts, wherein the molded component due to the gas pressure build-up between the die and the component of the Matrizenoberfläche is released and pressed onto the frame base. The finished workpiece can then be removed from the frame base and fed to the heat treatment become. The forming process can also take place in two stages insofar as in the first stage, the forming of the sheet-like blank is carried out by gas pressure, and in the second stage, the final formation of the sheet-like blank takes place mechanically by pressing the punch into the die, as in detail already to others Has been explained.

Fig. 1

zeigt eine Übersichtszeichnung der Erfindung zur Erläuterung der Bestandteile der Umformpresse;

Fig. 2

zeigt den Ausgangszustand der Presse nach Einlegen des flächenförmigen Rohlings aus Metall;

Fig. 3

zeigt den zusammengefahrenen Zustand der beiden Pressenteile vor dem Vorgang der Umformung;

Fig. 4

zeigt einen Zustand, bei dem der Stempel mit der positiven Gravur in die negative Gravur der Matrize eingefahren ist;

Fig. 5

zeigt das aus der Matrize ausgefallene oder ausgeworfene Werkstück bei auseinandergefahrenen Gestellteilen.

With reference to the drawings, the invention will be explained in more detail below by way of example.

Fig. 1

shows an overview drawing of the invention for explaining the components of the forming press;

Fig. 2

shows the initial state of the press after inserting the sheet-like blank made of metal;

Fig. 3

shows the contracted state of the two press parts before the process of forming;

Fig. 4

shows a state in which the stamp with the positive engraving is retracted in the negative engraving of the die;

Fig. 5

shows the ejected from the die or ejected workpiece with apart frame parts.

According to the FIGS. 1 to 5 is on the press upper part 2 of the forming press 1, the thermally insulated frame top 6 and attached to the press base 3, the frame base 7. Both frame parts are heatable, as described elsewhere. The insulation in each case shows the reference numeral 9. The frame top 6 has the also designated thermally insulated die 8 with the negative engraving 10th which is arranged interchangeably in the frame top in relation to the project, corresponding to the die, the frame base has the punch, designated 12, with the positive engraving 14, which is complementary to the negative engraving 10 of the die 8. That is, the positive engraving 14 of the punch 12 corresponds to the shape of the negative engraving 10 of the die 8 for forming the workpiece 42 from the blank sheet 26. The punch 12, which is displaceably mounted displaceably in the cylindrical space 16 formed by the frame base 7, shows a plurality of piston rings 18. The piston rings 18 provide primarily for a seal of the punch 12 relative to the cylindrical space 16. As already explained at the outset, is here also ensured by the piston rings that even at temperatures of the punch 12 of up to 1100 ° C for heating the positive engraving 14 with the aim of heating the blank 26, the punch 12 in the cylindrical space 16 is still movable; because by the piston rings 18, a different thermal expansion of the punch 12 on the one hand to the cylindrical space formed by the frame base 16 on the other hand can be compensated. That is, a "seizure" of the two components is highly unlikely even at very different temperatures and different materials. This in contrast to the prior art, which does not show such piston rings.

As can be seen in particular from the figures, the heating of the sheet-like blank 26 takes place at various points, as has already been explained above. On the one hand, a tempering device is provided as heating in the stamp 12, which bears the reference numeral 20. The heater 20 is located on the stamp base below the positive engraving 14 of the stamp. A further tempering device in the form of a heater 23 is arranged in or on the frame base, specifically where the die 8 rests on the frame base 7. corresponding For this purpose, the die 8 in this area also has a tempering device in the form of a heater 22 to at least partially heat the sheet-like blank 26, if necessary from two sides in this area, or to produce a heat profile. For heating the negative engraving 10 of the die 8, a further tempering device in the form of the heater 25 is provided in the bottom region of the negative engraving 10 of the die 8 between the frame top 6 and the negative engraving 10.

The pressure chamber 24 is formed by the underside of the sheet-like blank 26, the top of the positive engraving 14 of the punch 12 and by the frame base 7th

The pressure chamber 24 is connected by a connecting line 28 with a pressure generator 30 in connection. That is, the pressure generator 30, for example, a compressor, ensures an increase in the gas pressure in the pressure chamber 24th

The punch 12 has a piston-cylinder drive 32, which serves for the displacement of the punch 12 in the cylindrical space 16 formed by the frame base 7.

In the FIGS. 2 to 5 Now the process of forming is shown. Starting from the Fig. 2 is the positive engraving 14 in the starting position directly on the underside of the sheet-like blank 26, which is to be reshaped. The two frame parts 6 and 7 are in the extended state.

Fig. 3 shows the state in which the two frame parts 6 and 7 are moved together, and now provide together with the blank 26 for sealing the pressure chamber 24. In this state will now increased by the pressure generator 30, the gas pressure in the pressure chamber 24. Here, in a first step, the shaping of the sheet-like blank 26 in the negative engraving 10 of the die 8 by the gas pressure. From a certain forming state of the blank 26 of the punch 12 is then tracked, ie parallel to the deformation by the gas pressure of the punch 12 is tracked, the gas pressure increases due to the reduction of the gas volume, then possibly in the edge regions already by the positive engraving of the 14 Stamp 12 in conjunction with the negative engraving 10 of the die 8, the mechanical Endausformung, especially in the edge regions with a small radius to accomplish. That is, substantially immediately before reaching the Umformendzustands the further transformation purely mechanically by the shrinkage of the positive engraving 14 of the punch 12 in the negative engraving 10 of the die 8 takes place, especially if, for example, in the edge region small Umformradien to be formed accurately. However, the invention also encompasses the simultaneous operation of the stamp with the shaping by the gas pressure. Before the mechanical forming process in the wake of the gas forming, it makes sense to at least partially discharge the then harmful gas pressure between the punch and the nearly formed workpiece.

In order to prevent now during the forming process that builds up a counter-pressure within the negative engraving 10 of the die 8, a compensation line 36 is provided in the form of a tube between the sealed space 40 below the punch 12 and the space passing through the negative engraving 10 of the die 8 is formed. The state of the Endausformung results from the illustration according to Fig. 4 , Fig. 5 shows a representation in which the blank 26 is formed to the finished workpiece 42. When the equalizing pipe 36 is connected as a hose to a pressure generator (not shown), when the pressure inside the negative engraving 10 is increased, the pressure may increase Die 8 formed space a corresponding pressure for ejecting the workpiece 42, so the endausgeformten blank are constructed. The workpiece 42 is then ejected laterally from the forming press 1. In this context, the state of the art according to the DE 10 2010 106 299 A1 referenced where it is not recognizable how the finished workpiece to go after moving apart of the frame parts of the pressure-tight press housing or the blank to be introduced.

LIST OF REFERENCE NUMBERS

1

forming press

2

Press top

3

Press lower part

6

first frame part (frame top)

7

second frame part (frame base)

8th

die

9

insulation

10

negative engraving

12

stamp

14

positive engraving

16

Space (cylindrical)

18

piston ring

20

Heating on the stamp ground

22

Heating in the edge area of the die

23

Heating in the edge area of the frame base

24

pressure chamber

25

Heating the negative engraving

26

sheet blank

28

connecting line

30

pressure generator

32

Piston cylinder drive

36

compensation line

40

Space below the stamp

42

workpiece

Claims (15)

Forming press (1) for forming a sheet-like blank (26) made of metal with at least two mutually movable thermally insulated frame parts (6, 7), wherein a first frame part (6) has a die (8) with a negative engraving (10), and wherein the other second frame part (7) has a punch (12) movable in a space (16) of this frame part, wherein the sheet-like blank (26) above the punch (12) forms a pressure space (24) with the punch (12 ) on which the punch (12) receiving the second frame part (7) rests sealingly,
characterized,
in that the pressure space (24) can be acted upon by a pressurized gas from a pressure generator (30). Forming press according to claim 1,
characterized,
in that the punch (12) has a positive engraving (14) which is at least partially complementary to the negative engraving (10) of the die (8). Forming press according to one of the preceding claims,
characterized,
that the punch (12) in the use state of the forming press (1) in the space (16) of the other second frame part (7) is movable from bottom to top. Forming press according to one of the preceding claims,
characterized,
that the punch (12) pressure-tight manner in the space (16) of the other second frame part (7) is displaceably guided. Forming press according to claim 4,
characterized,
that the punch (12) by at least one radially encircling piston seal, for. B. a piston ring (18) in the space (16) of the other second frame part (7) is displaceably guided. Forming press according to at least one of the preceding claims,
characterized,
in that the die (8) of the one first frame part (6) and / or the punch (12) of the other second frame part (7) has at least one tempering device which can be controlled or regulated. Forming press according to claim 6,
characterized,
that for several tempering, the tempering controllable individually or are regulated. Forming press according to one of claims 4 to 7,
characterized,
in that the die (8) of the one first frame part (6) has a tempering device (22) in the area of the support on the other second frame part (7), and the other second frame part (7) is located in the region of the support for the flat blank (7). 26) also has a tempering device (23). Forming press according to one of the preceding claims,
characterized,
that the sheet-like blank (26) between the two frame parts (6, 7) is kept sealed. Forming press according to one of the preceding claims,
characterized,
that the starting position of the punch (12) in the cylindrical space (16) of the other second frame part (7) is such that the punch (12) with or without positive engraving (14) is located immediately in front of the blank sheet (26), but without deforming it. Forming press according to one of the preceding claims,
characterized,
in that the space (40) below the punch (12) communicates with the space formed by the negative engraving (10) of the die (8) through a compensating duct (36). Forming press according to one of the preceding claims,
characterized,
that the volume of air generated by the pressure generators (30) regularly depending on the current pressure in the pressure chamber or is controllable. A method for forming a sheet-like blank with a forming press according to at least one of claims 1 to 12, characterized by the following working steps: - placing the sheet-like blank (26) on the other second frame part (7); - closing the frame parts (6, 7), - Heating the sheet-like blank (26) on a relative to the material of the sheet-blank blank forming temperature; - Applying to the pressure chamber (24) with a pressurized gas; - Retracting the punch (12) in the negative engraving of the die (10); - Releasing the gas pressure at least to a level that allows the opening of the frame parts; - moving apart of the frame parts (6, 7) after completion of the forming; - Removal of the finished workpiece (42); - Moving the punch (12) to the starting position, which is
characterized in that the stamp rests against the underside of the blank or almost rests, Forming press according to claim 12,
characterized,
in that the holding of the frame parts (6, 7) takes place with a force in which the blank (26) is held sealed between the frame parts, without the material of the blank being able to flow laterally. Forming press according to claim 12,
characterized,
in that the holding of the frame parts takes place with a force which makes it possible to reshape the blank, in which case the material of the blank can flow from the outside into the negative engraving of the die.

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