DE102010060207A1 - Method and plant for producing a magnesium sheet component - Google Patents

Abstract

The invention relates to a method and a system for producing a component (2 ') from magnesium sheet with a forming tool (3) having a punch (3.1) and a die (3.2) for forming a semifinished product (2) from magnesium sheet, in particular a semifinished product in Form of a magnesium sheet, and a device (1) for heating the semi-finished product (2) before forming to an elevated temperature, preferably to a temperature of at least 200 ° C. In order to reduce the component costs, the invention proposes that the forming tool (3) be carried out without an internal heat source, be provided with a semi-finished product holder (3.3) on which the heated semi-finished product (2) can be used without direct contact with the punch (3.1) and the die (3.2) can be placed in the forming tool (3) and has a drive which effects a closing speed of the punch and die in the range from 15 mm / s to 500 mm / s.

Description

The invention relates to a method for producing a component from magnesium sheet by forming a semifinished product from magnesium sheet, in particular a semi-finished product in the form of a magnesium sheet, in which the semi-finished product before forming to an elevated temperature, preferably heated to a temperature of at least 200 ° C and in a forming tool having a punch and a die is formed. Furthermore, the invention relates to a system for producing a component from magnesium sheet.

Due to the hexagonal lattice structure of magnesium, magnesium sheets are difficult to reform at room temperature. In particular, components made of magnesium sheet, which should have a complex three-dimensional shape, must be hot-formed to avoid cracks. In general, magnesium plates are shaped in the heated state using tempered tools. In the prior art, various embodiments of tempered tools for forming magnesium sheets are known. For example, from the Korean Patent Application 10 2006 00 57 901 A a press for thermoforming of magnesium sheet is known, which is equipped with an electrical resistance heater. The resistance heating device is integrated in an upper tool part (die) and in an associated blank holder.

Tempered forming tools require in comparison to conventional tools used in cold forming a higher technical complexity and thus higher investment and higher operating costs. This negatively affects the cost of magnesium components.

The present invention has for its object to provide a method and a system for producing a three-dimensional component of magnesium sheet, which allow low component costs.

This object is achieved by a method with the features of claim 1 or by a system with the features of claim 9.

The inventive method is characterized in that for forming the heated to an elevated temperature, preferably to a temperature of at least 200 ° C semi-finished a forming without internal heat source forming tool is used, wherein the heated semi-finished product without direct contact with the punch and the die in The forming tool is placed and then converted at a forming speed in the range of 15 mm / s to 500 mm / s.

The system according to the invention is characterized in that the forming tool is designed without internal heat source, is provided with a semi-finished, on which the heated to an elevated temperature, preferably to a temperature of at least 200 ° C semifinished product without direct contact with the stamp and the Matrix can be placed in the forming tool, and has a drive that causes a closing speed of the punch and die in the range of 15 mm / s to 500 mm / s.

The present invention eliminates the additional expense caused by the temperature of the forming tool by means of an internal heat source. The invention provides for the processing of a heated magnesium semi-finished product in a forming tool without an internal heat source. As a result, the tool and operating costs and thus ultimately the component costs can be significantly reduced. In particular, in the manufacture of components in relatively small quantities can be achieved by reducing the cost of tools a significant contribution to the efficiency of the component.

Through experiments, the inventors were able to prove that a three-dimensionally shaped component can be made from a for example heated to 250 ° C magnesium plate in a non-tempered forming tool without cracking, if too high temperature losses are avoided before the actual forming process by a direct deposition of the heated board is prevented on the punch or the die during placement (insertion) of the board in the forming tool, and the subsequent forming takes place at a relatively high forming speed (15-500 mm / s).

The average cooling rate for a 2.00 mm thick magnesium sheet, which is heated to a temperature in the range of 200 ° C to 250 ° C, is for example in air at room temperature of 20 ° C between 2 and 12 K / s. This relatively low temperature loss can be ensured in a suitable transfer system, that the heated semi-finished product or the heated board has a sufficiently high starting temperature before forming to allow a defect-free, in particular crack-free component at given degrees of deformation.

The inventive use of a non-tempered tool for forming heated magnesium plates also results in positive effects in terms of dimensional stability and the Handling of the components thus produced. Because of the significantly reduced temperature that the component has when it is removed from the non-tempered forming tool, the component is dimensionally stable compared to a manufactured in a tempered tool component and thus less prone to unwanted deformations during its removal from the forming tool and the subsequent Handling, which has a favorable effect on the dimensional accuracy of the component. Furthermore, the components produced according to the invention can be handled more easily due to their significantly reduced temperature, which they have when they are removed from the non-tempered forming tool. Here, conventional transfer systems can be used which are not temperature-stable or have a comparatively low temperature stability.

In this context, an advantageous embodiment of the method according to the invention provides that a forming tool is used as the forming tool, whose punch and / or die have an active cooling device. As a result, the removal temperature of the component can be reduced faster, the dimensional accuracy of the component further improved and the handling of the component can be further simplified. This active cooling of the stamp and / or the die is particularly advantageous when relatively high numbers of pieces are to be formed in a given time, d. H. if the desired forming capacity should be relatively high. However, a heating of the forming tool due to the heated semi-finished product during production can be tolerated, if this does not have a negative impact on the dimensional accuracy of the finished component.

An advantageous embodiment of the invention, which allows the heated Magnesiumblechhalbzeug not directly deposited on the stamp or the die, is that the heated semi-finished product is placed on a forming tool associated Halbzeughalter, so that the essential surface area of the heated Semi-finished product before the actual forming process between the punch and die and spaced from these cantilevered in the ambient atmosphere is arranged. The ambient atmosphere, preferably ambient air, acts as a heat insulator. This ensures that the heated semi-finished undergoes only a very small cooling before the actual forming process. The semifinished product holder can be designed, for example, as an active sheet metal holder, which is positioned above a die associated with the die.

A further advantageous embodiment of the method according to the invention is characterized in that a semifinished product holder is used as a semifinished product holder whose surface region touching the heated semifinished product has a surface structure having porous or recesses. As a result, the thermal or temperature loss of the heated semifinished product caused by heat conduction from the heated semifinished product to the semifinished product holder is reduced.

Additionally or alternatively, a further advantageous embodiment of the method according to the invention provides that a semifinished product holder is used as a semifinished product holder whose surface area touching the heated semifinished product is formed from a material or has a coating which has a thermal conductivity of not more than 20 W / mK at 30 ° C to 100 ° C ambient temperature. This also makes it possible to reduce the heat or temperature loss caused by heat conduction from the heated semifinished product to the semifinished product holder.

A further advantageous embodiment of the method according to the invention is characterized in that a die is used as the die, in the forming surface, which faces the hot semi-finished product, recesses are formed which cause a reduction of the contact surface facing the heated semi-finished product. The depressions or the air contained therein acts heat-insulating, so that can be reduced in this way the heat or temperature loss of the heated semi-finished product.

A further advantageous embodiment of the method according to the invention provides that the semifinished product is transported directly into the forming tool by means of a transfer device equipped with a conductive heat source. As a result, the semifinished product to be formed can be given a sufficiently high starting temperature before shaping, and at the same time the temperature loss of the semifinished product can be minimized prior to forming.

Through the use of a non-tempered forming tool, a cost-effective integrated component trim during the forming of the semifinished product consisting of magnesium sheet is also conceivable. A further advantageous embodiment of the method according to the invention is accordingly characterized in that the semifinished product is simultaneously trimmed during forming with at least one cutting element integrated in the forming tool.

Further preferred and advantageous embodiments of the system according to the invention are specified in the subclaims.

The invention will be explained in more detail with reference to a drawing illustrating several embodiments. They show schematically:

1 a plant or process line for the production of three-dimensionally shaped components from magnesium semi-finished products;

2 a further embodiment of a process line for the production of three-dimensionally shaped components of magnesium semi-finished products; and

3 an inventive forming tool in vertical section view.

In the 1 The system shown essentially comprises a device 1 for heating a semifinished product 2 made of magnesium sheet and a forming tool 3 without internal heat source for forming the heated semi-finished product 2 , The semi-finished product to be formed 2 may be in the form of a magnesium sheet, for example.

The device 1 for heating the semifinished product 2 is designed here as a continuous furnace, preferably as a roller hearth furnace. The continuous furnace or roller hearth furnace 1 is equipped with inducers, radiant heaters, hot air burners and / or recuperative burners. Also, the use of infrared heaters for heating the semi-finished products to be reshaped 2 is conceivable.

In the embodiment shown, magnesium sheet blanks are to be reshaped 2 from a conveyor belt or a stockpile 4 taken and in the continuous furnace 1 heated to an elevated temperature, which is chosen so that the workpiece temperature at the end of the forming substantially still above 180 ° C to 220 ° C. For this purpose, the magnesium sheet to be formed or the semi-finished product 2 heated to a temperature in the range of 230 ° C and 260 ° C, for example.

The heated semi-finished product 2 is then by means of a transfer device 5 , Preferably a robot in the region of the outlet of the continuous furnace in the forming tool 3 without direct contact with the stamp 3.1 and the matrix 3.2 inserted. This is the forming tool 3 with a semifinished product holder (blank holder) 3.3 provided in the open state of the forming tool 3 is positioned above the stamp head, so that the semifinished product deposited thereon 2 neither the stamp 3.1 still the matrix 3.2 touched. In 1 can be seen that the placed in the forming tool board 2 first on the semi-finished product holder 3.3 is filed while doing both opposite the stamp 3.1 as well as towards the matrix 3.2 is arranged at a distance. This will cause the heated magnesium board to cool down too quickly 2 prevented.

Then the tool 3 closed to the heated semifinished product in a through the stamp 3.1 and the matrix 3.2 reshape the given shape. The deformation takes place with a relatively high deformation rate, so that the temperature loss of the heated workpiece (semifinished product) 2 is also kept low during the forming. To achieve a correspondingly high forming speed, the forming tool 3 a drive (not shown) having a closing speed of punch 3.1 and die 3.2 in the range of 15 mm / s to 500 mm / s causes.

The component thus produced 2 ' becomes after opening the forming tool 3 by means of a suitable transfer device 6 , preferably a robot from the forming tool 3 taken and optionally stored or stacked on a means of transport, such as a transport pallet or the like.

If the temperature loss for the respective component geometry or the respective degree of deformation due to the use of conventional tool steels should be too high, the tool 3 consist at least in parts of materials with lower thermal conductivity and / or have a coating that has a low thermal conductivity. In addition to ceramics, special tool steels can meet these requirements. For example, the stamp 3.1 and / or the die 3.2 of the forming tool 3 be formed, at least in some areas of a material having a maximum thermal conductivity of 20 W / mK at 30 ° C to 100 ° C ambient temperature. Alternatively, the reduction of the thermal conductivity can also be done with a suitable coating.

A further preferred embodiment of the system according to the invention is that of the heated semi-finished product 2 touching surface area 3.31 of the semi-finished product holder 3.3 a porous or depressions 3:32 having exhibiting surface structure. As a result, the temperature loss of the heated semifinished product 2 further reduced. Additionally or alternatively, it is provided that the heated semi-finished product 2 touching surface area 3.31 of the semi-finished product holder 3.3 is made of a material which has a relatively low thermal conductivity, or is coated with such a material. The thermal conductivity of the semifinished product holder 3.3 used material or one for the semi-finished product holder 3.3 The coating used is preferably not more than 20 W / mK at 30 ° C to 100 ° C ambient temperature.

2 shows a further embodiment of a system according to the invention for producing a three-dimensionally shaped component 2 ' made of magnesium sheet. This system differs from the system according to 1 in that the heating of a magnesium sheet metal plate to be reshaped 2 not in a continuous furnace, but in or with a robot-like transfer device 5 ' is carried out. The transfer device 5 ' is this with a heater or conductive heat source 5.1 equipped, so that the heating of the magnesium sheet 2 during its transport from a supply stack 4 or a conveyor belt in the forming tool 3 he follows. The conductive heat source or heating device 5.1 is in particular in gripping or holding elements of the transfer device 5 ' integrated, with which the magnesium sheet (semi-finished product) 2 taken or the forming tool 3 transported and stored there.

The forming tool 3 the in 2 shown plant is according to the forming tool 3 the system according to 1 designed so that so far to avoid repetition of the above description of the 1 is referenced.

In the in the 1 and 2 schematically illustrated plants are essentially continuously operating process lines. It is not shown that a processing of the coil is possible, ie that the material is unwound from a coil and depending on the existing process line either rectangular blanks are cut to length, for example, if a trimming occurs during or after forming, or shape blanks whose contoured dimensions of the essentially correspond to finished component.

In 3 is an inventive forming tool 3 shown schematically in vertical section view, the example in the Appendix 1 or 2 can be used. The forming tool shown in the open state in turn has a stamp 3.1 and a die 3.2 for forming a magnesium sheet board 2 on. The forming tool 3 contains no internal heat source. It is with a semi-finished product holder (board holder) 3.3 provided on which the heated board 2 without direct contact with the stamp 3.1 and the matrix 3.2 is placeable. The as a storage area for the heated board 2 serving surface area 3.31 of the semi-finished product holder 3.3 is in the open configuration state of the forming tool 3 first above the stamp 3.1 , The surface area 3.31 of the semi-finished product holder 3.3 has a groove-shaped recesses or depressions 3:32 provided surface structure. Furthermore, in the surface of the tamping head receiving trough of the die 3.2 Recesses or depressions 3.21 educated. The recesses or depressions 3:32 and 3.21 define air gaps or air ducts, which have a heat-insulating effect and thus a rapid heat or temperature loss of the heated board 2 prevent. The board 2 facing surface of the punch 3.1 , to reshape the board 2 into the cavity of the matrix 3.2 is retracted, on the other hand contains no air channels forming depressions, since this stamp surface here the actual shaping surface of the forming tool 3 represents.

To manufacture components from magnesium sheet at higher volumes 2 ' the temperature of the respective from the forming tool 3 to be removed component 2 ' can keep the stamp low 3.1 and / or the die 3.2 also be equipped with an active cooling (not shown). Such cooling may, for example, by a crown construction and / or by cooling channels in the stamp 3.1 and / or the die 3.2 be integrated.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• KR 1020060057901 A [0002]

Claims (16)

Method for producing a component ( 2 ' ) made of magnesium sheet by forming a semi-finished product ( 2 ) of magnesium sheet, in particular of a semi-finished product in the form of a magnesium sheet, in which the semifinished product ( 2 ) is heated to an elevated temperature, preferably a temperature of at least 200 ° C., before being formed, and in a die ( 3.1 ) and a die ( 3.2 ) forming tool ( 3 ) is formed, characterized in that for forming the heated semi-finished product ( 2 ) a forming tool without internal heat source ( 3 ), the heated semi-finished product ( 2 ) without direct contact with the stamp ( 3.1 ) and the die ( 3.2 ) in the forming tool ( 3 ) and then formed at a forming speed in the range of 15 mm / s to 500 mm / s. Method according to claim 1, characterized in that the heated semi-finished product ( 2 ) on a forming tool ( 3 ) associated semi-finished product holder ( 3.3 ) is placed. Method according to claim 2, characterized in that a semifinished product holder ( 3.3 ), the surface of the heated semifinished product ( 3.31 ) a porous or depressions ( 3:32 ) having surface structure. Method according to claim 2 or 3, characterized in that a semifinished product holder ( 3.3 ) is used, the heated semi-finished product ( 2 ) contacting surface area ( 3.31 ) is formed of a material or provided with a coating which has a thermal conductivity of 20 W / mK at 30 ° C to 100 ° C ambient temperature. Method according to one of claims 1 to 4, characterized in that as die a die ( 3.2 ) is used, in which the to be formed, heated semi-finished product ( 2 ) facing mold surface depressions ( 3.21 ) are formed, a reduction of the heated semi-finished product ( 2 ) effect facing contact surface. Method according to one of claims 1 to 5, characterized in that a forming tool ( 3 ) whose stamp ( 3.1 ) and / or die ( 3.2 ) have an active cooling device. Method according to one of claims 1 to 6, characterized in that the semifinished product ( 2 ) by means of a conductive heat source ( 5.1 ) equipped transfer device ( 5 ' ) directly into the forming tool ( 3 ) is transported. Method according to one of claims 1 to 7, characterized in that the semifinished product ( 2 ) during forming together with at least one in the forming tool ( 3 ) integrated cutting element is trimmed. Plant for producing a component ( 2 ' ) made of magnesium sheet with a stamp ( 3.1 ) and a die ( 3.2 ) forming tool ( 3 ) for forming a semi-finished product ( 2 ) made of magnesium sheet, in particular a semifinished product in the form of a magnesium sheet, and a device ( 1 . 5.1 ) for heating the semifinished product ( 2 ) before forming to an elevated temperature, preferably to a temperature of at least 200 ° C, characterized in that the forming tool ( 3 ) with no internal heat source, with a semi-finished product holder ( 3.3 ), on which the heated semifinished product ( 2 ) without direct contact with the stamp ( 3.1 ) and the die ( 3.2 ) in the forming tool ( 3 ) and has a drive that causes a closing speed of punch and die in the range of 15 mm / s to 500 mm / s. Plant according to claim 9, characterized in that the heated semi-finished product ( 2 ) touching surface area ( 3.31 ) of the semi-finished product holder ( 3.3 ) a porous or depressions ( 3:32 ) having surface structure. Plant according to claim 9 or 10, characterized in that the heated semi-finished product ( 2 ) touching surface area ( 3.31 ) of the semi-finished product holder ( 3.3 ) is formed of a material or provided with a coating which has a thermal conductivity of 20 W / mK at 30 ° C to 100 ° C ambient temperature. Installation according to one of claims 9 to 11, characterized in that the stamp ( 3.1 ) and / or the die ( 3.2 ) of the forming tool ( 3 ) is formed of a material at least in some areas or provided with a coating which has a thermal conductivity of not more than 20 W / mK at 30 ° C to 100 ° C ambient temperature. Installation according to one of claims 9 to 12, characterized in that the stamp ( 3.1 ) and / or the die ( 3.2 ) of the forming tool ( 3 ) have an active cooling device. Installation according to one of claims 9 to 13, characterized in that the forming tool ( 3 ) one with a conductive heat source ( 5.1 ) equipped transfer device ( 5 ' ), with which the semifinished product to be formed ( 2 ) directly onto the semifinished product holder ( 3.3 ) is placeable. Installation according to one of claims 9 to 14, characterized in that in the die ( 3.2 ) Wells ( 3.21 ) are formed, a reduction of the heated semi-finished product ( 2 ) effect facing contact surface. Installation according to one of claims 9 to 15, characterized in that the forming tool ( 3 ) is provided with at least one cutting element.

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