WO2011032685A1

WO2011032685A1 - Method for pre-treating and preparing a sheet metal part

Info

Publication number: WO2011032685A1
Application number: PCT/EP2010/005647
Authority: WO
Inventors: Mathias Kotzian; Roland Malek; Mohamed Mekkaoui Alaoui; Dieter Niehues
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2009-09-17
Filing date: 2010-09-15
Publication date: 2011-03-24
Also published as: CN102695809A; EP2478121A1; EP2478121B1; DE102009042026A1

Abstract

The invention relates to a method for pre-treating and preparing a sheet metal part (5) having a metal layer (3) for subsequent processing. In order to make the improved pre-treatment and preparation possible, tempering of the sheet metal part (5) for the duration of a first time period in a first temperature range, and thereby transforming the metal layer (3) by tempering is provided. During a second time period, the execution of at least one of the elements of the following group is provided: Maintaining the first temperature range; cooling down the sheet metal part (5); cooling down the sheet metal part (5) to an ambient temperature; storing the sheet metal part (5); heating the sheet metal part (5) to a second temperature range as necessary for subsequent processing.

Description

description

Process for pretreating and providing a sheet metal part

The invention relates to a method for pretreating and providing a sheet-metal part provided with a metallic layer for a subsequent processing step.

Methods for treating sheet metal parts are known. These may be, for example, methods for heating the sheet metal parts for a subsequent forming and / or curing step. DE 201 22 563 U1 relates to a workpiece with very high-quality mechanical properties, consisting of one with an intermetallic

Alloy compound coated, deep-drawn sheet metal blank, which has been produced by cutting a rolled, in particular hot-rolled strip steel sheet, wherein the strip steel sheet is coated with a metal or a metallic alloy, which ensure protection of the surface and the steel, the intermetallic

Alloy compound resulting from a transformation of the coating of the metal or metal alloy before or after deep drawing, the intermetallic

Alloy compound is formed on the surface by the transformation realized by a temperature increase above 700 ° C and ensures protection against corrosion and decarburization of the steel and causes a lubricating function, wherein the metal or metallic alloy in the coating of zinc or an alloy the basis of zinc is. From DE 31 02 638 A1 a method and apparatus for maintaining the ^'temperature of the metal plates during transportation and treatment breaks is known. The temperature of the stacked continuously cast metal plates is kept at a desired temperature level of more than 1,000 ° C, that the stack of is surrounded by a thermally insulating housing which is surrounded by an induction heating coil DE 699 07 816 T2 discloses a coated hot rolled and

cold rolled steel sheet with very high strength after a thermal treatment known. The coating is based on aluminum or on an aluminum alloy.

The object of the invention is to enable an improved pretreatment and provision of a provided with a metallic layer sheet metal part for subsequent processing, in particular to allow a more flexible and / or shorter cycle times having production of the sheet metal part.

The object is solved with the features of the independent claims.

CONFIRMATION COPY The object is in a method for pretreating and providing a metal layer provided with a sheet metal part for a subsequent processing step with annealing of the sheet metal part for a first period of time in a first

Temperature range and thereby transforming the metallic layer by means of tempering, waiting for a second period of time while maintaining the first temperature range and / or cooling the sheet metal part and / or cooling the sheet metal part to an ambient temperature and / or storage of the sheet metal part, and heating the sheet metal part to a for solved the subsequent processing step necessary second temperature range. The subsequent processing step may be, for example, a forming step and / or

Hardening step act. Advantageously, it is possible to separate the pretreatment or the provision and the subsequent processing step

perform, for example by means of two different devices. The temporal decoupling can advantageously take place during the waiting of the second period of time. This makes it advantageously possible to make the production of the sheet metal part more flexible. The first

Time period ends when at least 60% of the mass of the metallic layer has been transformed. Advantageously, the first time period ends when at least 80%, 90% or 95% of the mass of the metallic layer has been transformed. Advantageously, the second period lasts at least 1 minute, but may take days or months. In particular, it is advantageously possible first to perform the transformation of the metallic layer by means of the first device and temporally decoupled from the heating of the sheet metal part to the second temperature range, for example, austenitization of the sheet metal part can take place, and immediately thereafter the further processing step, such as a forming and / or curing, which can be done by means of the second device. Advantageously, shorter cycle times can be realized. In particular, it is possible to provide different cycle times for the first device and the second device, so that it is possible to dispense with designing the entire production to the longest cycle time. Advantageously, a logistic buffering of the sheet metal parts can take place while waiting for the second period of time, for example by storing the same at the ambient temperature. Alternatively and / or additionally, it is also possible to logistically buffer the sheet metal parts at an arbitrary temperature level, for example in the preheated state in the first temperature range. In this case, there is no further transformation or implementation of the metallic layer, but it can be advantageous to dispense with a completely new heating of the sheet metal parts, which can be advantageously saved energy at a comparatively good thermal insulation and comparatively short buffer time. The following

Processing step can take place in the manner of a hardening and / or forming step in any manner, in particular as disclosed in DE 201 22 563 U1. These

Document, in particular the figures and the associated description is incorporated by reference into the content of this application. Transforming the metallic ones Layer and / or their chemical composition can be carried out in any manner, in particular as disclosed in DE 699 07 816 T2. This document,

in particular the information on the chemical composition of the metallic layer in the description and in the claims, is incorporated by reference into the content of this application. The annealing and / or heating and / or keeping warm of the sheet metal part, in particular in the first and / or second temperature range, can be done in any manner, for example by means of a furnace, a hot air blower, by means of inductive

Heating and / or by means of radiation and / or the like. In particular, this can be done as in DE 31 02 638 A1. The content of this application, in particular the figures and the associated description, in particular of inductive heating, by

Reference made to the content of this application.

In a further embodiment of the method it is provided that the first

Temperature range below a transformation point for austenitization of the

Sheet metal part lies. Advantageously, the transformation of the metallic layer can first take place in a comparatively small temperature range. The transformation point of the sheet metal part is dependent on its composition, in particular of a carbon content.

In a preferred embodiment of the method it is provided that the first

Temperature range is below a melting temperature of the metallic layer.

Advantageously, it can be prevented that the metallic layer changes adversely, for example drips off, while still advantageous by means of diffusion

Transformation of the metallic layer into an alloy-like layer can take place.

In a further preferred embodiment of the method, it is provided that the first temperature range is slightly above a melting temperature of the metallic layer, without the metallic layer being adversely affected, for example dripping off, whereby the transformation of the metallic layer into an alloy-like layer nevertheless takes place advantageously by means of diffusion can. It is understood that the first temperature range can vary depending on the chemical composition of the metallic layer.

In a further embodiment of the method it is provided that the second

Temperature range is above the transformation point. Advantageously, the austenitization of the sheet metal part can take place above the forming temperature. Subsequently, advantageously, a hot forming process and a curing process by rapid cooling, such as quenching and / or a tool cooling done. In a further embodiment of the method, it is provided that the first temperature range comprises a temperature value of 873 K to 1,003 K. Advantageously, a particularly good transformation of the metallic layer can be achieved with this value.

In a further embodiment of the method it is provided that the second

Temperature range comprises a temperature value of 1,223 K. Advantageously, a particularly good austenitization and / or hot forming of the sheet metal part can take place in this area.

In a further embodiment of the method, a tempering of the sheet metal part in the second temperature range is provided for a third period of time. Advantageously, the austenitization can take place during the third period of time, which can be selected such that it can take place to a sufficient extent.

Advantageously, the sheet metal part should consist of one of the alloys 22MnB5, 25CrMo4, 34CrMo4, 42CrMo4, 25CrMoS4, 34CrMoS4 or 42CrMoS4. The steel 22MnB5 should be used advantageously in the following composition, the

given values represent the percentage by mass in the alloy:

C: 0.20 to 0.25; Si: 0.15 to 0.40; Mn: 1, 10 to 1, 40; Cr: <0.35; Mo: <0.35; P: <0.025; S: <0.005; Ti: 0.020 to 0.050; AI: 0.020 to 0.060; B: 0.002 to 0.005.

In a further embodiment of the method, it is provided that the metallic layer has a mixture with an aluminum weight fraction of at least 90% and also portions of silicon and iron. Advantageously, with this composition of the metallic layer, a particularly high surface quality, good corrosion protection, a sliding action for the subsequent treatment step and / or a particularly good transformation can be achieved. In particular, in this embodiment of the method, it is provided that the first temperature range comprises a temperature value of 1,003 K, since at this value, a particularly good transformation of the metallic layer can be achieved.

The object is also achieved in a device for pretreating and providing a metal layer provided with a sheet metal part for a subsequent processing step, which is designed, set up and / or constructed in particular for performing a method described above. The device has an insulation housing for

Enclosing and holding a variety of sheet metal parts, a heat source for

Temperature control of the sheet metal parts in the first and / or second temperature range and a separating device for separating and providing the sheet metal parts for the subsequent processing step. This results in particular in the advantages described above. Advantageously, by means of the insulating housing, an undesirable loss of heat of the sheet metal parts during annealing and / or heating can be avoided. By means of

Heat source can be supplied to the sheet metal parts the necessary energy. By means of the separating device, the sheet metal parts can advantageously be separated from one another and

be supplied tempered according to the subsequent processing step.

In one embodiment of the device it is provided that the

Singling device has a lifting table and a pawl feed. By means of the lifting table, the sheet metal parts, in particular in stacked form, the latch feed can be supplied. By means of the pawl feed the separated sheet metal parts can be supplied to the subsequent processing step.

In a further exemplary embodiment of the device, it is provided that the heat source has a field inductor, for example a transverse or longitudinal field inductor for heating the sheet metal part to the first temperature range. Advantageously, by means of

Längsfeldinduktors be directed in the longitudinal direction of the sheet metal part field for introducing heat-convertible energy in the sheet metal part. By means of the transverse field inductor, a field running in a transverse direction of the sheet metal part can be built up, by means of which energy convertible into heat energy can be introduced into the sheet metal part.

In a further exemplary embodiment of the device, it is provided that the heat source has a field inductor, for example a transverse or longitudinal field inductor for heating the sheet metal part to the second temperature range. These field inductors the

Heat sources can each have one or more effects.

Further advantages, features and details emerge from the following

Description in which - if appropriate with reference to the drawing - at least one

Embodiment is described in detail. Described and / or illustrated features form the subject of the invention, or independently of the claims, either alone or in any meaningful combination, and in particular can additionally also be the subject of one or more separate invention (s). The same, similar and / or functionally identical parts are provided with the same reference numerals. Show it:

Fig. 1 A device for pretreating and providing one with a metallic

Layer provided sheet metal part for a subsequent processing step; and Fig. 2 is a half-plan view of a Längsfeldinduktor the device shown in Fig. 1.

1 shows a device 1 for pretreating and providing a sheet-metal part 5 provided with a metallic layer 3 for subsequent processing. The subsequent processing can be carried out by means of a further device, not shown, for example by means of a forming device and / or a device for hardening the sheet metal part. 5

In Fig. 1, a plurality of sheet metal parts 5 is shown, which are in the form of a stack 7 in an interior of an insulating housing 9. The stack 7 can be moved by means of a lifting table 11 in the direction of a double arrow 13 up and down. At an upper end of the stack 7, the device 1 has a separating device 15, by means of which the sheet-metal parts 5 can be singulated. By means of the separating device 15 each of the sheet metal parts 5 can be lifted from the remaining stack 7 so that it can be brought into engagement with a pawl 17 of a pawl feed device 19. By means of

Pawl feed device 19, the respective individual sheet metal part 5 can be pushed in the direction of an arrow 21 through an opening of the insulating housing 9.

For heating the stack 7 or at least the respectively separated sheet metal part 5 in a first temperature range, the insulating housing 9 has a Längsfeldinduktor 23. By means of the longitudinal field inductor 23, a field can be generated by the sheet metal part 5 in a longitudinal direction, by means of which the necessary energy for heating in the first temperature range in the sheet metal part 5 can be introduced. The longitudinal field inductor 23 can for this purpose have a coil through which a current flows which extends in a circumferential direction around the sheet metal part 5 and / or the stack 7. Advantageously, it is possible to heat only the upper area of the stack 7 accordingly.

The sheet metal parts 5 have a metallic layer 3, which preferably has a 90% proportion of aluminum and iron and silicon. The first temperature range is advantageously chosen so that the metallic layer 3 is not melted. It is advantageous to a transformation of the layer 3, in particular by means of diffusion, wherein a

Alloy-like outer skin of the sheet metal part 5 is formed. The sheet-metal part 5 tempered by means of the longitudinal field inductor 23 in the first temperature range can be pushed through the opening in the insulating housing 9 after a first period of time has passed by means of the pawl feed device 19. Advantageously, it is also possible to let elapse after the first period of time an arbitrarily long second period of time, for example during a Period of time in which the corresponding annealed sheet metal part of the downstream device for further processing is not yet needed.

Adjacent to the opening of the insulating housing 9, a Querfeldinduktor 25 is arranged, which may also have an electrical current-carrying winding for generating a transverse to the sheet metal part 5 extending field. For heating the corresponding sheet metal part 5 to a second temperature range, the corresponding sheet metal part 5 can be pushed in a simple manner by means of Kllnkenvorschubvorrichtung 19 under the Querfeldinduktor 25. By way of example, a sheet-metal part 5 heated to the second temperature range is shown on a right-hand side of the transverse-field inductor 25 as viewed in the orientation of FIG.

The sheet metal part 5, which has been heated to the second temperature range by means of the transverse field inductor 25, can be austenitized by means of an allotropic transformation and is thus prepared for further processing, in particular hardening by means of quenching and / or tempering

Hot forming.

The first temperature range can have a value between 873 K and 1,003 K. The second temperature range may have a value of 1.223 K.

2 shows a schematic plan view in a half-side view of the apparatus 1 shown in FIG. 1. In this case, a lid of the insulating housing 9 is shown transparent for simplicity, so that the around the respective sheet metal part 5 extending around

Longitudinal field inductor 23 is visible. It can be seen that the longitudinal field inductor 23 extends within the insulating housing 3. Alternatively, it is also conceivable that the

Longitudinal field inductor 23 is disposed outside of the insulating housing 9.

By means of the lifting table 11 of the stack of boards or stack 7 is raised according to a request of the other device. The further device may be, for example, a press for a forming process, for example by means of

Deep drawing, acting; The further device may for example have a stroke rate of 8 of the sheet metal parts 5 per minute.

The stack 7 passes through the longitudinal field inductor 23 and is preferably heated to the value between 873 K and 1,003 K. In this case, the diffusion layer is advantageously formed from the metallic layer 3. The separating device 15 or a Platinenspreizer the

Separating device 15 separates the sheet metal part 5 and the stacked on the stack 7 boards.

The pawl feed device 19 pushes the sheet metal parts 5 out of the insulating housing 9 in the direction of the arrow 21 under the transverse field inductor 25.

The Querfeldinduktor 25 heats the corresponding sheet metal part 5 to the value of about 1.223 K.

Thereafter, the sheet metal part 5 and the board is inserted into the further device, not shown, which may be, for example, a hot forming tool. Advantageously, between the annealing by means of Längsfeldinduktors 23 and the expulsion of the corresponding sheet metal part 5, the second period of time to be awaited.

Advantageously, the entire stack 7 can be heated, wherein the stack 7 can be sized so large that due to the cycle times of the downstream device for

Further processing first passes the first time period for transforming the metallic layer and can then be waited during the second period until the corresponding sheet metal part 5 has reached an uppermost position on the stack 7 and separated by means of the separating device 5 and can be ejected by means of the pawl feed device 19. The diffusion time, that is, the first period, may be, for example, about 10 minutes.

Advantageously, the stack 7 can be slowly heated by means of the Längsfeldinduktors 23 until it has reached the first temperature range. For this purpose, the longitudinal field inductor 23 can advantageously be designed as a low-frequency inductor.

The heating of the sheet metal part to the second temperature range can be done in a short time, advantageously in a short time the corresponding individual sheet metal part 5 a

Reaches and / or exceeds the austenitizing temperature. For this purpose, the Querfeldinduktor 25 may be designed as a high-frequency inductor.

Alternatively and / or additionally, it is possible to use any heat source for heating and / or tempering the sheet metal parts 5 or the separated sheet metal part 5, for example a hot air blower, an oven, heat radiation and / or the like. LIST OF REFERENCE NUMBERS

I device

3 metallic layer

5 sheet metal part

7 stacks

9 insulating housing

I I lift table

13 double arrow

15 separating device

17 pawl

19 pawl feed device

21 arrow

23 longitudinal field inductor

25 transverse field inductor

Claims

claims

Apparatus for pretreating and providing a sheet metal part (5) provided with a metallic layer (3) for subsequent processing, with tempering of the sheet metal part (5) for a period of time in a temperature range and thereby transforming the metallic layer (3) by means of annealing wherein the apparatus comprises: an insulation housing (9) for enclosing and keeping a plurality of the sheet metal parts (5), a heat source for tempering the sheet metal parts (5) in a temperature range, a separating device (15) for separating and providing the sheet metal parts (5) for the subsequent processing step.

Apparatus according to claim 1, wherein the separating device (15) comprises a lifting table (11) and a pawl feeding device (19).

Device according to one of the preceding two claims, wherein the heat source comprises a field inductor (23) for heating the sheet metal part (5) to the first

Temperature range has.

Device according to one of the preceding three claims, wherein the heat source comprises a field inductor (25) for heating the sheet metal part (5) to the second

Temperature range has.

Process for pretreating and providing a metal part (5) provided with a metallic layer (3) for subsequent processing, in particular with a device according to one of the preceding claims, comprising:

Annealing the sheet metal part (5) for a first period of time in a first temperature range, and thereby transforming the metallic layer (3) by means of annealing, during a second time period, executing at least one element of the following group: holding the sheet metal part in the first temperature range, cooling the sheet metal part (5), cooling the sheet metal part (5) to an ambient temperature, storing the sheet metal part (5), and after the second time period heating the part Sheet metal part (5) to a necessary for subsequent processing second temperature range.

6. The method according to any one of the preceding claims, wherein the first

Temperature range is below a transformation point for austenitizing the sheet metal part (5).

7. The method according to the preceding claim, wherein the first temperature range is below a melting temperature of the metallic layer (3).

8. The method according to any one of the preceding claims, wherein the second

Temperature range is above the transformation point.

9. The method according to any one of the preceding claims, wherein the first

Temperature range values from 873 K to 1,003 K covers.

10. The method according to any one of the preceding claims, wherein the second

Temperature range comprises a value of 1,223 K.

A method according to any one of the preceding claims, comprising:

Annealing the sheet metal part (5) in the second temperature range for a third period of time.

12. The method according to any one of the preceding claims, wherein the metallic layer comprises a mixture with an aluminum weight fraction of at least 90% and silicon and iron.