TW201303248A - A method for heating a shaped component for subsequent press hardening and a continuous furnace for sectional heating to a higher temperature of a shaped component preheated to a predetermined temperature - Google Patents

Abstract

A method is described for heating a shaped component (2) for subsequent press hardening, with the shaped component (2) being heated at first to a predetermined temperature and subsequently being heated to a higher temperature in sections by means of heating elements (7) of a heating element field (10) which can be triggered independently from on another. In order to ensure an advantageous temperature progression it is proposed that the shaped component (2), during its conveyance through the theating element field (10), is heated by means of the heating element (7) which are arranged in longitudinal and transverse rows (8 and 9) with respect to the conveying direction (3) and can be triggered at least in groups with different heating power. (Fig. 2)

Description

a method for heating a molded component for subsequent in-mold hardening and a continuous heating furnace for locally heating a molded component preheated to a predetermined temperature to a higher temperature

The present invention relates to a method for heating a forming element for subsequent in-mold hardening, the forming element being first heated to a predetermined temperature and then individually triggered by a heating unit zone The unit is heated and heated to a higher temperature.

When in-mold hardening of a shaped component heated to a predetermined processing temperature, thermal shock will produce harden microstructures via a cooled pressing tool, resulting in stainless steel (austenitic), tensile strength (tensile) Strengths) up to 1500 MPa Mpa, and elongation is within 6%.

Such high tensile strength is usually only required for a localized area of the workpiece, while other areas require, for example, a higher 15% to 17% elongation. In order to ensure the material properties of different specific regions, different localized regions are subjected to different heat treatments before in-mold hardening of the molded components, so that only the high tensile strength regions of the molded components are heated to a higher than alloy AC3. The temperature of the point will result in a separate structural transformation under a subsequent in-mold hardening condition. For this purpose (German Patent DE 10 2006 018 406 A1), a cooling unit will be provided in the low tensile strength region, so that part of the heat energy supplied to one of the forming elements is dissipated, thus forming a component section in the cooling unit zone. It remains below the temperature required for the formation of a stainless steel structure. However, relatively high energy input is disadvantageous. In order to ensure that the energy input will be limited to the extent necessary, for this purpose (European Patent EP 1426454 A1), a continuous furnace is subdivided into at least two of each other transversely to the conveying direction. Separate heatable areas. In at least two such regions, the forming element extends transversely to the conveying direction and can thus be heated to different processing temperatures in the region. However, precise temperature guidance of the localized regions of different heating of the shaped elements is almost impossible.

In order to enable the shaped element to be heated regionally to a temperature above the AC3 point, further proposed (European Patent No. 2,143, 808 A1), the forming element is first heated to a temperature below the AC3 point by a conventional heating procedure. The regions prepared for the formation of an austenitic structure are heated to a temperature higher than the AC3 point by the help of the infrared lamp zones which are independently switchable, so that only the infrared lamps are activated. In the area, additional heat energy is introduced into the forming element. The additional regional heating of such shaped elements does not include a continuous heat treatment of one of the shaped elements.

In addition, it is finally proposed (European Patent EP 2090667 A1) that the forming element is in a continuous heating furnace having hot gases from nozzle fields and having a longitudinal column and a lateral column associated with the conveying direction. The individual nozzles of the nozzle zone are independently triggerable for firing. The nozzle triggering nozzles that are independent of one another can be selected in accordance with the shape of the forming element so that the application of the hot gas can be limited to the area of the respective shaped portion.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for heating a shaped component to a different temperature, for example, a continuous transfer of the shaped component to a subsequent heat treatment required for subsequent in-mold hardening, which may be heated differently These parts have improved temperature guidance.

Based on the above described method for heating a shaped element for subsequent in-mold hardening, the present invention achieves the stated object of heating the shaped element as it is transported through the heating unit zone by means of a heating unit, The heating unit is arranged to be arranged in a column and a row with respect to the conveying direction, and is triggered by at least a group of different heating electric power.

At the same time, due to this measurement, the heating unit can be triggered by different heating power. First, an important prerequisite for improving the temperature guiding of the forming element is met. Due to the possibility of triggering at least the heating units that are independent of each other in the column and the course, there may be an additional effect on the temperature of the forming element, in a longitudinal band extending in the conveying direction, during the conveying of the component, in order to It can reach the preset temperature standard of the longitudinal zone as it is, and can maintain the standard for the time preset period. Thus, for example, depending on the need, to compensate or enhance the different temperature zones in which the shaped component is heated, to the predetermined initial temperature caused by the size of the shaped component and such mass distribution, such that when the respective processing temperatures are reached, Processing temperatures that vary by region can still be maintained during a predetermined processing period.

In the direction of the belt-like transport, the shaped elements can be cooled by selecting a triggerable cooling device associated with the column of the heating unit, for the purpose of providing additional influence for temperature guidance of the zone regions of different heat treatments. This selected cooling will dissipate the additional heat in a known manner, which is desirable to maintain a predetermined temperature profile when subjected to local heat treatment of the shaped component. However, the heat loss associated with heat dissipation must be considered.

In order to carry out the heating method according to the invention, a continuous heating furnace can be provided for locally heating a forming element preheated to a predetermined temperature to a higher temperature, comprising a through-heating furnace for forming the component The conveyor belt of the mask and the heating unit area, the heating unit area is associated with the conveyor belt, and is constituted by heating units that can be independently triggered by each other. If a heating unit arranged in a column or row relating to the conveying direction of the conveyor belt is arranged, at least the group in the longitudinal and lateral directions is triggered by different heating power, and the additional heat is transmitted in a good manner. Forming the component so that the shaped component can be treated by the row of the heating cells within the length of the heating cell zone so that the respective longitudinal strips of the shaped component can maintain a predetermined temperature during the length of the continuous heating furnace. The situation is essentially independent of the temperature guidance of an adjacent longitudinal strip.

Although it is only appropriate to introduce the additional heat required separately into the shaped element to be treated, so that different heating units will be used, a particularly advantageous construction condition can be obtained, when the heating unit is arranged to be electrically resistively heated, since The control of the heating power of the heating units can be arranged in a particularly simple manner.

When required, in order to ensure heat dissipation in the longitudinal strip region of the shaped element, the optionally triggerable cooling means corresponds to the longitudinal strips of the heating unit. One of the potential cooling zones can be additionally defined by a spacer between the cooling devices, and the thermal insulation formed by the cooling devices is between the columns of the heating cells.

The effectiveness of such cooling devices is clearly dependent on their distance from the cooled region of the forming element. In this way, it is possible to derive a particularly advantageous construction precondition for the cooling device, which is arranged in a casing duct which can be connected to an air-cooling fan, so that it is in the longitudinal direction of the cooled forming element. The distance between the belt and the cooling devices can be kept low without attenuating the heating power. When the heating unit is triggered, the outer casing conveying pipe will be separated from the air cooling fan. A cooling gas is blown into the region of the shaped member to be processed through the outer casing transfer pipe, in such a manner that the cooling performance can be enhanced.

2 is a block diagram showing a continuous heating furnace 1 for the heat treatment of the forming element 2, and the forming element 2 is introduced into the continuous heating furnace 1, such as a sheet metal blank, which is successively contained, One of the conveying directions 3 is continuously placed on the width of the furnace to heat the forming element 2 to a predetermined temperature in the heating zone 4; a portion of the forming element 2 in the longitudinal strip corresponding to the conveying direction 3 The heated heating zone 5; and, in order to impart a different temperature profile to the maintenance zone 6, can be formed into different microstructures in the respective longitudinal zones during subsequent in-mold hardening. In the heating zone 5 and the heating zone 6, the heating unit 7 is disposed in the longitudinal column 8 and the lateral column 9 of a heating unit zone 10. The forming element 2 is conveyed through the continuous heating furnace 1 by means of a conveyor belt 11, which is indicated by reference numeral 12 in FIG. The heating unit 7 is disposed above and below the conveyor belt 11. The furnace cover 14 lined with the thermal insulation 13 comprises, in the region of the longitudinal row 8 of the heating unit 7, a cooling device 15 in the form of a cooling duct which is optionally connected to a cooling fan. According to a modification of the embodiment, such cooling ducts can represent the outer casing duct of the heating unit 7, so that the cooling device 15 is located closer to the forming element 2, which improves the cooling of a supply due to such a configuration. Cooling efficiency of electricity. Between the respective cooling zones provided by the cooling device 15, a separator web 16 will be provided which forms a thermal insulation to define a cooling zone that is contrasted with each other and a heating zone adjacent to the cooling zone.

The heating unit 7 can be optionally arranged to be electrically resistively heated and is triggered independently of each other at least in groups with different heating power. Figure 2 shows the percentage ratio of heating power, whereby the individual heating units 7 can be triggered. This means that, relative to the number 100, the heating unit 7 is triggered and has full heating power, while the number 0 indicates that the heating unit 7 is turned off, and in view of the number 50, the heating unit 7 calibrated with half of the heating power is triggered.

Figure 3 shows the temperature profile of the selected longitudinal strips a, b, c, d, in relation to the transport direction 3 of the forming element 2, which is triggered by the heating unit 7 when passing through the furnace, and is indicated by heating power. Heating unit 7. As shown, in the normal heating zone 4, the forming element 2 is heated to a preset temperature T1 for one of the AC ₃ points. Due to the distribution of masses, for the respective longitudinal strips a, b, c, d of the shaped element 2, at the output of the heating zone 4, different temperatures T _a , T _b , T _c , T _d will be obtained. In view of the fact that the temperature in the heating zone 5 will be raised above the temperature T1 of the AC ₃ point in the longitudinal zones a, b and d, the temperature in the zone of the longitudinal zone c will remain below the temperature T1. For this reason, the heating unit 7 in the longitudinal row 8 of the heating unit zone 10 associated with the longitudinal strip c will be closed, which will result in only low heat introduction, via the heating of adjacent longitudinal columns 8 in the region of the heating zone 5. Unit 7, the heating unit is triggered by half of the heating power. The temperature profile t _{c of} the longitudinal strip c illustrates this fact. As for a continuous heating, at the output of the heating zone 5, the temperature profile t _a can result in an excessive processing temperature. For this reason, a reduced supply is only ensured by the heating unit 7 of the adjacent longitudinal row 8 of the heating unit zone 10 in the longitudinal zone a, as shown by the temperature profile t _a based on the zone of the heating zone 5 . For the longitudinal strips b and d, since the initial temperature of the heating zone 4 is relatively low, such longitudinal strips b and d in the region of the heating zone 5, the introduction of heat is necessary, in the heating zone 5 Output to ensure that each temperature is maintained. Corresponding to the longitudinal strips b and d, the heating unit 7 in the heating zone 5, thus depending on the full heating power in the longitudinal strip b region and 60% heating power in the longitudinal strip d region, thus producing a curve progression t _b and t _d , according to this, for the relevant longitudinal strips b, d, the output of the heating zone 5 ensures that the temperature is maintained.

In order to maintain the processing temperature at the output of the heating zone 5, the heating cells 7 corresponding to the sustain zones 6 of the respective longitudinal strips are triggered by respective electrical power. A heating output of 50% is separately obtained for maintaining the temperature profile t _a , which is raised to 60% in the last heating unit region by considering the respective heating power of the heating unit 7 of the adjacent longitudinal column 8 . By connecting to the associated longitudinal array of heating means 7 of the 8, to ensure that the temperature profile t _b, of such a heating unit to be triggered to 80% or 70% of the heating power. For the longitudinal strip d of the shaped element 2, the heating unit 7 in the sustaining zone 6 is first triggered with 60% heating power and then with 70% heating power. Due to the sensitive control of the heat of the strip-shaped afferent forming element, a predetermined temperature profile is advantageously maintained, with the aid of additional cooling possibilities, providing a further adjustment possibility, as shown in Figure 1, if A preset temperature profile requires additional cooling of the strip zone. Only the continuous transport of the forming element 2 through the continuous heating furnace 1 can be achieved under different thermal conditions in different regions of the forming element, a prerequisite for the subsequent in-mold hardening in order to carry out the different microstructures. Prior to the local heating of the forming element, since all of the component areas are typically preheated to a predetermined initial temperature, not only advantageous efficiencies are possible for different heating of the forming elements, but also the plated forming elements are advantageous for heat treatment. This can be achieved because the diffusion of the plating into the shaped component can be ensured by the usual preheating of all component areas.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the present invention should be included in the following patents. Within the scope.

1. . . Continuous heating furnace

2. . . Molding element

3. . . Conveying direction

4. . . Heating zone

5. . . Heating zone

6. . . Heating zone

7. . . Heating unit

8. . . Vertical column

9. . . Horizontal column

10. . . Heating unit area

11. . . conveyor

12. . . Transport roller

13. . . Thermal insulation

14. . . Heating furnace cover

15. . . Cooling device

16. . . Separate network

The method of the present invention will be described in detail below by way of illustration, wherein:

Figure 1 is a cross-sectional schematic view showing a continuous heating furnace according to the present invention;

Figure 2 is a schematic block diagram showing the distribution of heating elements illustrating a heating unit zone of a continuous heating furnace;

Figure 3 is a graph showing the temperature profile of the respective longitudinal strip regions of the shaped element as it is conveyed through the continuous furnace.

1. . . Continuous heating furnace

2. . . Molding element

7. . . Heating unit

8. . . Column

11. . . conveyor

12. . . Transport roller

13. . . Thermal insulation

14. . . Heating furnace cover

15. . . Cooling device

16. . . Separate network

Claims (6)

A method for heating a forming element (2) for subsequent in-mold hardening, the forming element (2) will first be heated to a predetermined temperature and then independently of each other by a heating unit zone (10) The triggered heating unit (7) is heated in sections to a higher temperature, characterized in that the forming element (2) is transported through the heating unit zone (10) by means of the heating unit (7) And heating, the heating unit (7) is disposed in a nematic direction (longitudinal column (8) and lateral column (9)) with respect to the conveying direction (3), and is at least grouped with different heating electric power trigger. The method according to claim 1, characterized in that the molding element (2) is cooled in a strip shape in the conveying direction (3), by arbitrarily triggering the association with the heating unit (7) Cooling device (15) of longitudinal column (8). A continuous heating furnace (1) for locally heating a molding element (2) preheated to a predetermined temperature, comprising a heating furnace cover (14) for the molding element (2) and a conveyor belt (11) of the heating unit zone (10), the heating unit zone (10) being associated with the conveyor belt (11) and consisting of heating units (7) which are independently triggerable with each other, characterized in that The heating units (7) placed in a nematic (longitudinal column (8) and lateral column (9)) associated with the conveying direction (3) of the conveyor belt (11), at least in groups of longitudinal and transverse directions Trigger in the direction with different heating power. The continuous heating furnace (1) according to claim 3, characterized in that the heating units (7) are arranged to be electrically resistively heated. The continuous heating furnace (1) according to the third or fourth aspect of the patent application, characterized in that the arbitrarily triggered cooling device (15) is associated with the longitudinal columns of the heating units (7) (8) ). The continuous heating furnace (1) according to claim 5, wherein the units (7) are arranged to be disposed in a casing conveying pipe connectable to an air cooling fan.