CN-113290148-B - Method for molding sheet material into parts of complex shape having regions of different properties

Abstract

A method for molding a sheet into a complex shaped part with regions of different mechanical properties. The method involves a first heating step of the sheet carried out by means of a kiln before shaping the component. The kiln includes a main body having a roll shape with a plurality of sectors extending in a radial direction with respect to a longitudinal axis of the roll body. The sectors are configured to each receive a sheet, the body having a roller shape being arranged to carry a plurality of sheets simultaneously. The kiln further includes a plurality of heating elements incorporated into the roller-shaped body to heat the sheet in contact with the roller body. The kiln comprises at least one electronically controlled drive motor arranged to rotate the roller-shaped body about the longitudinal axis of the kiln to change the position of the sectors relative to the inlet and outlet ports. The method further comprises an additional heating step after extracting the sheet from the kiln.

Inventors

• D. Basan
• M. Colossio

Assignees

• C.R.F.阿西安尼顾问公司
• C.R.F.阿西安尼顾问公司

Dates

Publication Date

20231107

Application Date

20210219

Priority Date

20200221

Claims (14)

1. 1. A method for molding a sheet (L) into a complex-shaped part with regions of different mechanical properties, wherein the following steps are envisaged: -arranging at least one mould for shaping the sheet (L), the mould being configured to produce the component; -arranging at least one kiln (1) to carry out a heating step of the sheet (L) before shaping the sheet (L), the kiln (1) comprising: a housing (2) of refractory material, said housing having at least one inlet port (6) and one outlet port (7) arranged for inserting and extracting, respectively, sheets (L) from the kiln (1), -a body (3) having a roll shape, which is arranged inside the housing (2) and has a plurality of sectors (4) extending in a radial direction with respect to a longitudinal axis (X) of the body (3), which sectors (4) are configured to each receive a sheet (L) in such a way that the body (3) is designed to carry a plurality of sheets (L) simultaneously, a plurality of heating elements (5) incorporated in the body (3) for heating the body (3) in such a way that the body (3) is arranged to heat the plurality of sheets (L) at the areas where the plurality of sheets (L) are in contact with the body (3), -at least one electronically controlled drive motor arranged to rotate the body (3) about the longitudinal axis (X) so as to change the position of the sectors (4) with respect to the inlet port (6) and the outlet port (7); inserting a plurality of sheets (L) into the sectors (4) and uniformly heating the sheets (L) to a predetermined temperature by means of the kiln (1), removing the sheet (L) thus heated from the kiln (1), after extracting the sheet (L) from the kiln (1), an additional heating step is carried out, in which the sheet (L) is locally heated only at one zone, so as to obtain a sheet (L) having zones heated to different temperatures, -subjecting the sheet (L) to a forming step and uniformly cooling the locally heated sheet (L) inside the mould, so as to obtain a complex-shaped part with regions having different mechanical properties.
2. 2. Method according to claim 1, characterized in that the additional heating step is carried out by means of a heating station with a diode laser.
3. 3. Method according to claim 1 or 2, characterized in that the kiln (1) comprises an actuator (8) configured to push a sheet (L) carried by one of the sectors (4) towards the outlet port (7).
4. 4. A method as claimed in claim 1 or 2, wherein the kiln (1) comprises mechanical retention members associated respectively with each sector (4) to support the sheet (L) inside the sector (4) and prevent the sheet (L) from accidentally exiting the sector (4) during the rotation of the body (3) before the completion of the heat treatment.
5. 5. Method according to claim 1 or 2, characterized in that the inlet port (6) is formed along the upper side of the housing (2) so that the sheet (L) can be inserted into the kiln (1) in a vertical direction, and in that the outlet port (7) is made along the side wall of the housing (2) so that the sheet (L) can be extracted from the kiln (1) in a horizontal direction perpendicular to the insertion direction.
6. 6. A method according to claim 1 or 2, characterized in that the sectors (4) are arranged at constant intervals along the body (3) so as to be spaced apart from each other by an angle of about 45 °.
7. 7. Method according to claim 1 or 2, characterized in that, after the additional heating step after extracting the sheet (L) from the kiln (1), the steel sheet (L) has: a thermal zone (L1) having a temperature of about 900 ℃; and a zone (L2) at a lower temperature, reaching a temperature of about 450 ℃.
8. 8. Method according to claim 2, characterized in that an electronic control unit is associated with the kiln (1), said electronic control unit being programmed to determine the heating cycle of the sheet (L) and all its operating parameters.
9. 9. Method according to claim 8, characterized in that the drive motor is controlled to interrupt the rotation of the body (3) when carrying out the loading step of the kiln (1) so as to introduce sheets (L) through the inlet port (6) and to extract sheets (L) from the kiln (1) through the outlet port (7) during the unloading step.
10. 10. A method according to claim 1 or 2, wherein the component is a motor vehicle component.
11. 11. A method according to claim 1 or 2, wherein the component is a center pillar of a motor vehicle body.
12. 12. A method according to claim 3, characterized in that an electronic control unit is associated with the kiln (1), which is programmed to determine the heating cycle of the sheet (L) and all its operating parameters by controlling the kiln (1), the heating element (5), the drive motor and the actuator (8).
13. 13. Kiln (1) for heating a sheet (L) to manufacture a part of complex shape, prior to the step of shaping said sheet (L), comprising: a shell (2) of refractory material, said shell having at least one inlet port (6) and one outlet port (7) arranged for inserting and extracting, respectively, sheets (L) from the kiln (1), -a body (3) having a roll shape, which is arranged inside the housing (2) and has a plurality of sectors (4) extending in a radial direction with respect to a longitudinal axis (X) of the body (3), which sectors (4) are configured to each receive a sheet (L) in such a way that the body (3) is designed to carry a plurality of sheets (L) simultaneously, -a plurality of heating elements (5) incorporated in the body (3) for heating the body (3) in such a way that the body (3) is arranged to heat the plurality of sheets (L), -at least one electronically controlled drive motor arranged to rotate the body (3) about the longitudinal axis (X) so as to change the position of the sectors (4) with respect to the inlet port (6) and the outlet port (7).
14. 14. Kiln (1) according to claim 13, characterized in that the component is a motor vehicle component with regions of different mechanical properties.

Description

Method for molding sheet material into parts of complex shape having regions of different properties Technical Field The present application relates to a method for molding sheet material into complex shaped parts with regions of different mechanical properties, in particular motor vehicle parts such as, for example, center pillars ("pillars B") of motor vehicle bodies. In particular, the application relates to a method of the type: wherein a heating step of the sheet is provided before the shaping step for manufacturing the final part. Background In order to obtain parts of complex shape, made of metallic material, characterized by local variations in their mechanical properties, the prior art is to prepare semi-finished sheet metal products manufactured according to the "tailored blank" technique. In order to manufacture components of the type indicated above, other known techniques envisage subjecting the component to a localized heat treatment. In the context of the present application, the previously proposed technique is to prepare a mold in which a part of complex shape is formed, the mold having a series of cooling channels configured to cool only a portion of the mold and, therefore, only a portion of the part obtained after molding. One of the disadvantages of this production method is: after partial cooling, undesired deformations are obtained in certain areas of the component. Methods of the type indicated at the beginning of the present description have also been proposed in the past, which envisage locally heating some areas of the sheet metal element prior to the forming step. An example of such a method is described in document US2019/0032162 A1. One of the technical problems encountered in the methods of the type indicated above lies in the fact that: kiln lines provided for carrying out the heating step of the sheet prior to shaping the complex-shaped parts are rather cumbersome and not very efficient, both from the point of view of the energy consumption required to operate these lines and from the point of view of construction time, at the cost of manufacturing economy. Disclosure of Invention Object of the application The object of the present application is to provide a method for moulding sheet material into parts of complex shape, in particular motor vehicle parts with regions having different mechanical properties, which overcomes the drawbacks indicated above. A further object of the present application is to provide a method compatible with the needs of the automotive sector, that is to say that in any case guarantees the possibility of obtaining parts of complex shape starting from sheet metal with reduced thickness, with relatively low forming times and energy consumption and therefore compatible with the productivity of the automotive sector. Disclosure of Invention To achieve this object, the application relates to a method of the type indicated at the beginning of the present description, wherein the following steps are envisaged: -arranging at least one mould for shaping a sheet, configured to produce the motor vehicle component; -arranging at least one kiln to carry out a sheet heating step prior to shaping the sheet, the kiln comprising: a housing of refractory material having at least one inlet port and one outlet port arranged for insertion and extraction of sheets from the kiln, respectively, a body having a roll shape, which is arranged inside the housing and has a plurality of sectors extending in a radial direction with respect to the longitudinal axis of the roll body, the sectors being configured to each receive a sheet in such a way that the roll-shaped body is designed to carry a plurality of sheets simultaneously, a plurality of heating elements incorporated in the roller-shaped body configured to heat the roller body in such a way that a body having a roller shape is arranged to heat the plurality of sheets at the areas where the plurality of sheets are in contact with the roller body, -at least one electronically controlled drive motor arranged to rotate the roller-shaped body about the longitudinal axis so as to change the position of the sectors relative to the inlet and outlet ports; inserting a plurality of sheets into said sectors and uniformly heating them to a predetermined temperature by means of said kiln, -removing the heated sheet material from the kiln, after extracting the sheet from the kiln, an additional heating step is carried out in which the sheet is locally heated at only one zone, so as to obtain a sheet having zones heated to different temperatures, -subjecting the sheet to a shaping step and uniformly cooling the locally heated sheet in said mould, so as to obtain a complex-shaped part with regions having different mechanical properties. Preferably, the additional heating step is performed by means of a diode laser heating station. Preferably, the kiln comprises an actuator configured to push the sheet coming from one of the sectors towa