Device for curing sheet metal components

Abstract

The invention relates to a device for curing sheet metal components. The device comprises a base plate (01) and a head plate (02), which are connected to one another, via guide elements, such that the distance between them can be changed, in order that an open and a closed state can be adopted. Between the base plate (01) and the head plate (02), an adjustable component space (03) remains, in which a component (04) to be cured can be inserted. A drive is provided to change the distance between the base plate (01) and head plate (02). Numerous pressure piece pairs (06), each consisting of a base plate pressure piece (06a) and a head plate pressure piece (06b), are attached, axially oppositely, to the base plate (01) and head plate (02), respectively. At least one pressure piece of each pressure piece pair has an axially displacable pressure piston (07) and therefore the axial distance between the ends of the pressure pieces of a pressure piece pair directed towards one another can be changed. Numerous coolant nozzles (08) are provided, via which a coolant can be introduced into the component chamber (03) through an allocated recess (09) in the base plate (01) or in the head plate (02) in order to cool the component (04) to be cured.

Description

[0001] Device for hardening sheet metal components

[0002] The invention relates to a device for hardening sheet metal components. These can be formed or unformed hardenable sheet metal components, such as those required in automotive construction, but also in other areas. The device is particularly suitable for hardening formed components, but flat blanks or unformed components can also be hardened with the device.

[0003] In order to harden sheet metal components, they are usually heated to over 900°C, in particular to the respective austenitizing temperature, and then - preferably while forcibly maintaining the desired shape - shock-cooled with the aid of a coolant.

[0004] CN 113249 553 A describes a process for quenching steel workpieces. In a first step, a fluid blowing process is used to apply a cooling medium directly to the surface of the steel workpiece, which has been heated to at least the austenitizing temperature, and to cool it to a temperature of 250-450°C within a controlled time. In the second step, the liquid cooling medium is brought into direct contact with the surface of the steel workpiece, causing the workpiece temperature to drop below 80°C within a controlled time of 6 to 20 seconds.

[0005] DD 242 428 A1 describes a device for hardening sheet metal in a quenching bath using pressure plates to prevent distortion. For this purpose, a flow is generated in a quenching medium using displacement devices connected to the movable pressure plates. This flow is directed to the edge areas of the workpiece to be hardened, thereby achieving an increased quenching effect. The displacement device is arranged on the side of the pressure plates facing away from the workpiece and consists of an enclosed, circular sector-shaped space. The pressure plates can be pivoted relative to each other about axes of rotation.

[0006] A device for the distortion-free hardening of thin sheet metal is known from DD 201154 A1. The device has an upper and a lower hardening plate and uses a circulating hardening agent. The hardening plates are arranged at an angle to the horizontal plane, with the hardening agent supply located at the lower end of the hardening plates and the hardening agent outlet located at the upper end. Groove-like depressions run through the hardening plates, through which the hardening agent is guided on both sides of the sheet. The depressions are arranged such that each depression on one hardening plate is opposite a web on the opposite hardening plate.

[0007] DE 890804 B describes a device and method for quenching metals, sheets, and strips brought to hardening temperature using quenching liquids or gases. The quenching liquids or gases are divided into individual streams that have different temperatures across the width of the strip or sheet. The strip or sheet brought to hardening temperature is brought into only indirect contact with the quenching liquid or gas in a quenching zone, passing through a thermal barrier before entering the tempering zone.

[0008] In DE 2856 392 C3 a quenching device for

[0009] Hardening of sheets of different widths is described. This comprises an upper frame, each of which supports sets of guide and follower rollers, as well as a casing around the rollers, and which defines a space for the quenching liquid. Retractable deflection plates are arranged on both sides of the longitudinal axis of the device, perpendicular to the direction of sheet passage.

[0010] EP 0857 544 A2 shows a holding device for workpieces with a clamping jaw having a plurality of clamping pins with a circular cross-section, aligned parallel to one another, laterally adjacent to one another, and individually displaceable in their main direction of extension, a frame laterally enclosing the clamping pins, and a fixing device for fixing the clamping pins relative to the frame by means of a lateral fixing force. An open pressure chamber is provided on the rear side of the clamping pins facing away from the workpiece. Pressure medium can escape from the pressure chamber onto the respective workpiece through free spaces between the clamping pins. The described holding device is not suitable for fixing glowing sheet metal parts, since the clamping pins adapt to the component and would thus lead to uncontrolled deformation of the component.This device is also unsuitable for hardening components, since elements for a uniform and rapid supply of coolant cannot be easily integrated.

[0011] DE 102017 128574 B3 discloses a tempering unit for a furnace device for heat-treating a blank. The tempering unit comprises a tempering body arranged in a furnace chamber. The tempering body has a plurality of receiving bores and a plurality of tempering pins, wherein the tempering pins are mounted in the receiving bores so as to be movable relative to the tempering body. The tempering pins are controllable, so that a tempering group of the tempering pins can be extended from the tempering body toward the blank. Hardening of metallic workpieces is not possible with the tempering unit because a component cannot be fixed in the unit.

[0012] DE 102016 110 677 A1 also describes a tempering device for components, in particular for wheel rims. The device has a housing in which an at least partially closed tempering chamber is formed. Furthermore, a nozzle matrix is ​​provided with numerous nozzles through which a tempering medium flows onto the component. A control unit is configured to control a first nozzle group and a second nozzle group independently of one another such that a first tempering medium with a first tempering characteristic and a second tempering medium with a second tempering characteristic flow onto the component (150). The component is not fixed during tempering. The device is therefore not suitable for hardening sheet metal components, as these would distort during tempering.

[0013] DE 102009 004 125 A1 describes a device for the pressure-applied fixation of workpieces to be thermally treated. The device comprises a support device on which at least one workpiece rests during a hardening or cooling process. The support device provides support positions in only one horizontal plane and a hold-down device arranged above the support positions, which has a plurality of hold-down tools with hold-down ends directed toward the support positions.The clamping tools are each individually arranged for vertical movement and can be subjected to pressure. This creates a free space between each clamping end and the support positions when the fixture is loaded or unloaded. This space is completely closed during operation, ensuring that each clamping end rests either on a support position or on a workpiece to be thermally treated. However, it has been shown that the fixture is unsuitable for hardening sheet metal components, as it does not allow for a defined fixation of the components, which would lead to dimensional deviations during hardening.

[0014] Forming and hardening techniques have been used in technology for a long time, although the basic procedure has changed little in recent decades. The starting material is sheet metal, preferably alloyed manganese-boron steels such as 22MnB5, 22MnB8, or others. These steels are characterized, among other things, by the ability to increase strength through heat treatment. The sheets can be coated without a coating, with a zinc layer, or with an aluminum-silicon layer to prevent scaling and provide corrosion protection. The commonly used hot forming processes can be divided into two groups.In direct hot forming, a preformed blank is heated in a furnace, then formed and hardened in a press using cooled tools. Subsequently, scale and oxide layers are removed by sandblasting, and finally, the parts are trimmed, preferably using laser cutting systems. In indirect hot forming, preformed parts are first produced in a press and then heated in a furnace. This is followed by form hardening in a press using cooled tools, and finally, scale and oxide layers are removed by sandblasting. In both processes, the components are hardened in a press using cooled tools. This makes the tools expensive and the process time-consuming.Based on the prior art according to DE 102009 004 125 A1, one object of the invention can be seen in providing an improved device for hardening sheet metal components that is easily adaptable to different components and eliminates the need for expensive, cooled pressing or forming tools. Hardening should be possible in a comparatively short time and while maintaining the desired shape and dimensional stability of the components, thus eliminating the need for post-processing of the components.

[0015] These and other objects are achieved by a device for hardening sheet metal components according to the appended claim 1.

[0016] The device according to the invention is suitable for hardening sheet metal components and is adapted in size, stability, and material to the components to be hardened. The device comprises a base plate and a head plate, which are connected to each other via guide elements at an adjustable distance. Thus, the two plates or the device formed by them can assume an open and a closed state. In the open state, when the device is used, a single component or several components to be hardened are placed between the base plate and the head plate in an adjustable component space. The component can already be heated to the austenitizing temperature or, in alternative embodiments, can also be heated to this temperature within the device. In the latter case, the device comprises suitable heating elements, for example integrated heating wires.The device further comprises at least one drive for varying the distance between the base plate and the head plate. The drive can be implemented, for example, by integrated electric motors, pneumatic or hydraulic cylinders, or external force-generating units.

[0017] In addition, the device features numerous pairs of pressure pieces, each consisting of a base plate pressure piece and a head plate pressure piece. The two pressure pieces of each pair are mounted axially opposite one another on the base plate or the head plate, such that the mutually facing ends of the pressure pieces are essentially aligned. At least one pressure piece, preferably both pressure pieces of each pressure piece pair, each have an axially displaceable, fixable pressure stamp, such that the axial distance between the mutually facing ends of the pressure pieces of a pressure piece pair can be changed and fixed. The pressure pieces are attached to the base plate or head plate in such a way that the component to be hardened is positioned and clamped between the mutually facing ends of the pressure pieces when it is inserted into the device.The individual pressure pad pairs are adapted to the shape of the component to be hardened, so that the pressure stamps facing each other rest against the component to maintain its shape during the further hardening process and prevent distortion of the component at numerous clamping points. The pressure pads are adapted to the shape of the respective component, in particular by adjusting the respective distance between the ends of the pressure pads belonging to a pressure pad pair and shifting them to the desired plane and fixing them there.

[0018] The fixture can be easily and quickly adapted to different components by adjusting the pressure piece pairs. This allows the fixture to be configured for hardening different components, thus replacing expensive cooled press tools that can only be used for a specific component.

[0019] The device also has numerous coolant nozzles located outside the component space, with each coolant nozzle allowing a coolant to be introduced into the component space through an associated recess either in the base plate or in the top plate. This serves to cool the component to be hardened, which is inserted into the component space. The base plate and top plate therefore have numerous recesses to allow the supply of coolant. The coolant nozzles are connected to a coolant system and can be supplied with coolant together or, alternatively, individually or in groups. Since the coolant nozzles are not located in the component space itself, they do not hinder the positioning and fixation of the component during the hardening process in any way, thus resulting in particular variability of the device and ensuring the supply of coolant to all areas of the component.The coolant nozzles are preferably positioned so that they can apply coolant to the entire surface of the component to be hardened. This ensures that all areas of the component can be cooled simultaneously and evenly during hardening.

[0020] A key advantage of the device is that it enables the hardening of two- or three-dimensionally formed sheet metal parts, which are normally prone to significant dimensional and shape changes due to rapid temperature changes, outside of cooled pressing tools (hot forming tools). This significantly reduces the cost of the hardening process. This is achieved for the first time through the inventive combination of numerous, adjustable pressure piece pairs (clamping points) and the simultaneous integration of numerous coolant nozzles at a defined distance from the sheet metal surface to be cooled. This allows a wide variety of sheet metal components with different material thicknesses to be heat-treated reliably using one and the same device.

[0021] According to a preferred embodiment, a water-air mist, water, an emulsion, or another medium suitable for hardening the components is used as the coolant. Particularly preferably, the temperature and volume of the coolant delivered to the component via the coolant nozzles are adjustable so that the component is cooled from the austenitizing temperature (starting temperature) to a target temperature of approximately 150°C within a period of less than 20 seconds, preferably less than 15 seconds, in particular within 12 seconds or even less.

[0022] Preferably, the coolant nozzles and the recesses on or in the base plate and the head plate are arranged so that the component to be hardened can be wetted by the coolant over its entire surface from at least one side. Particularly preferably, there are numerous recesses in both the base plate and the head plate through which the coolant nozzles spray the coolant, so that the component is wetted with the coolant from both sides. The coolant nozzles can preferably be attached to the base plate or head plate via spacers.

[0023] Both pressure plates of each pressure plate pair each have an axially movable pressure ram. This allows the pressure rams to be axially adjusted relative to both the base plate and the head plate, allowing them to be highly customized to the shape of the component to be hardened. The component to be hardened is thus clamped between the pressure rams on both sides, ensuring that the specified shape is held securely at multiple points, even if material stresses occur during the hardening process.

[0024] The axially movable pressure dies are preferably adjustable manually or independently of one another via pressure piece drives. The pressure piece drives can be activated electrically, hydraulically, or mechanically, for example. In particular, the pressure dies are axially movable via a thread or replaceable spacers. After the axial adjustment of the pressure dies has been carried out, they are fixed again so that they do not adjust themselves during the hardening process. The axially movable pressure dies are particularly preferably conical in shape and are preferably made of a ceramic material or have a ceramic coating to ensure low adhesion to the surface of the component to be hardened. In alternative embodiments, the pressure dies can also be made of steel or composite materials.

[0025] A preferred embodiment is characterized by the fact that the drive for changing the distance between the base plate and the head plate is a mechanical, pneumatic, hydraulic, or electric drive. Generally, transmission gears can be used, or the drive can be coupled to the plates without a gear.

[0026] Particularly preferably, the drive and the number of pressure piece pairs are matched to one another in such a way that in the closed state, each pressure piece has a contact force of at least

[0027] 10 N acts on the component to be hardened.

[0028] Further advantages and details of the invention will become apparent from the following description of a preferred embodiment, with reference to the drawings. They show:

[0029] Fig. 1 is a simplified sectional view of an embodiment of a device according to the invention for hardening sheet metal components;

[0030] Fig. 2 is a detailed drawing of the device according to Fig. 1;

[0031] Fig. 3 is a perspective view of the device according to Fig. 1.

[0032] Fig. 1 and Fig. 2 show a device according to the invention for hardening sheet metal components, each in a side sectional view, with Fig. 2 showing a section of the device on an enlarged scale. The device comprises a base plate 01 and a head plate 02, which are connected to one another via guide elements (not shown) so that their distance can be adjusted. By changing the distance, the plates can be converted from an open to a closed state. Between the base plate 01 and the head plate 02 there thus remains an adjustable component space 03, into which one (or more) components 04 to be hardened can be inserted. A drive (not shown) is provided for changing the distance between the base plate 01 and the head plate 02.

[0033] Numerous pressure piece pairs 06 are positioned between the base plate 01 and the head plate 02, each consisting of a base plate pressure piece 06a and a head plate pressure piece 06b. The base plate pressure piece 06a is fastened to the base plate 01. The head plate pressure piece 06b is axially aligned opposite the base plate pressure piece 06a and is attached to the head plate 02. In the embodiment shown, both pressure pieces of the pressure piece pair 06 each have an axially movable pressure stamp 07 at their mutually facing ends, so that the axial distance between the pressure stamps is variable. The distance between the pressure stamps is adjusted at the respective location depending on the thickness of the component 04. The position of the component gap remaining between the opposing pressure stamps in relation to the base plate and head plate is adapted to the shape of the component.

[0034] The device also has numerous coolant nozzles 08 through which a coolant can be dispensed. The coolant nozzles 08 are each attached to the base plate 01 or the head plate 02 at an axial distance from the plate, with adjacent coolant nozzles 08 being spaced apart from one another by a distance determined such that the escaping coolant can reach essentially all surface areas of the component 04 to be hardened. To ensure that the coolant can be applied to the component 04, recesses 09 are provided in the base plate 01 and in the head plate 02, with the coolant nozzles 08 each being assigned to such a recess 09.

[0035] Before the actual hardening process, the component 04 to be hardened later is first cold-formed in a press using the conventional method. After the forming process, the component 04 is heated, for example, in an oven to over 900°C. The components can also be heated using other methods or even within the device according to the invention. Once the heating process is complete, the component is placed in the device. For this purpose, the base and head plates are in the open state. Previously, the pressure piece pairs 06 were adapted to the shape of the component 04 to be hardened. The placed component 04 is now clamped in the device by the base and head plates being closed, i.e. being moved towards one another. In the closed state, the pressure stamps 07 thus rest against the component 04 at numerous positions thereon. Within a few seconds, the component 04 is then evenly distributed by the supply of coolant, for example,Cooled to 150°C. This increases the hardness / strength of the component.

[0036] Due to the different stress distributions within the component, free cooling would cause the component to warp. The material stresses occurring during cooling are absorbed and compensated for by the pressure piece pairs. According to a further developed embodiment, the coolant nozzles 08 can be opened at staggered times, allowing a controlled application of coolant to the component via the coolant nozzles 08. This can also contribute to reducing or compensating the material stresses in component 04.

[0037] Fig. 3 shows the device again in a perspective view. It can be seen that numerous pressure piece pairs 06 are attached to the base plate 01 or head plate 02 for flat components 04, and numerous coolant nozzles 08 are provided.

[0038] Rust and acid-resistant materials are particularly suitable for all components of the device in order to keep wear to a minimum. A suitable coating which prevents corrosion of the base material can also be used. For the preferably conical pressure stamp 07, a ceramic compound is preferable, as this results in less heat dissipation from the component 04 to be hardened. The contact surface of the pressure stamp should be as small as possible (point-like). A preferred contact force of at least 10 N can be expected for each pressure piece 06. The pressure pieces are designed to be axially adjustable in the component direction. This can be achieved using a thread or by using spacers. The pressure pieces 06a, 06b preferably have a length of approximately 40 mm so that the component surface can still be easily reached by the coolant. The center-to-center distance between adjacent pressure pieces is preferably no more than 50 mm.This distance from the component edge should preferably not exceed 5 mm. To ensure that the coolant can reach the component to be hardened unhindered, the remaining webs between adjacent recesses in the base and head plates should preferably be no wider than 15 mm. The pressure pads 06 are attached to these webs.

[0039] To ensure the precise closing of the device, robust guide elements are selected. These are preferably wear- and corrosion-resistant. The device can be closed and opened, for example, by the one-sided drive of the head plate 02 if the base plate 01 is fixed to the frame. A reverse or double-sided drive is also possible.

[0040] The fixture size depends on the component size and the number of components to be hardened simultaneously. Scaling the fixture size is therefore easily possible. Reference symbol Base plate Head plate Component space Component to be hardened Pair of pressure pieces

[0041] 06a Base plate pressure piece

[0042] 06b Head plate pressure piece pressure stamp coolant nozzle recess

Claims

A device for hardening sheet metal components, comprising: a base plate (01) and a head plate (02), which are connected to one another via guide elements so that their distance is variable, in order to be able to assume an open and a closed state, wherein an adjustable component space (03) remains between the base plate (01) and the head plate (02), into which at least one component (04) to be hardened can be inserted; a drive for changing the distance between the base plate (01) and the head plate (02); numerous pressure piece pairs (06), each consisting of a base plate pressure piece (06a) and a head plate pressure piece (06b), which are mounted axially opposite one another on the base plate (01) or the head plate (02).the head plate (02), wherein the axial distance between the mutually directed ends of the pressure pieces of a pressure piece pair is variable; characterized in that both pressure pieces (06a, 06b) of each pressure piece pair (06) each have an axially displaceable, fixable pressure stamp (07), and in that numerous coolant nozzles (08) are arranged outside the adjustable component space (03), wherein a coolant can be introduced into the component space (03) via each coolant nozzle, in each case through an associated recess (09) which is located either in the base plate (01) or in the head plate (02), in order to cool the component (04) to be hardened which is inserted in the component space (03). Device according to claim 1, characterized in that the coolant nozzles (08) and the recesses (09) in the base plate (01) and the head plate (02) are arranged such that the component (04) to be hardened can be wetted by the coolant over its entire surface from at least one side. Device according to claim 2, characterized in that the coolant nozzles (08) and the recesses (09) in the base plate (01) and the head plate (02) are arranged such that the component (04) to be hardened can be wetted by the coolant over its entire surface from both sides. Device according to one of claims 1 to 3, characterized in that the axially displaceable pressure stamps (07) can be adjusted manually or via pressure piece drives. Device according to claim 4, characterized in that the pressure stamps (07) are axially displaceable via a thread or replaceable spacers.Device according to one of claims 1 to 5, characterized in that the axially displaceable pressure stamps (07) are conical and made of a ceramic. material or have a ceramic coating. Device according to one of claims 1 to 6, characterized in that the drive for changing the distance between the base plate (01) and the head plate (02) is a mechanical, pneumatic, hydraulic, or electric drive. Device according to one of claims 1 to 7, characterized in that the drive and the number of pressure piece pairs (06) are coordinated with one another in order to exert, in the closed state, a contact force of at least 10 N on each pressure piece pair on the material to be hardened. Component (04). Device according to one of claims 1 to 8, characterized in that the coolant nozzles (08) are dimensioned to heat the component (04) to be hardened within a maximum of 15 seconds from an initial temperature of 900°C to a To cool to a target temperature of 150°C at the most. Device according to one of claims 1 to 9, characterized in that it further contains heating elements for heating the component to be hardened.

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