EP0215032B1 - Process and installation to permit the assembly line thermo-mechanical working, with little deformation of workpieces; also application of the process - Google Patents

Abstract

In the installation, the heating facility (2), the hardening press (4), the tempering facility (6) and the cooling facility (8) are directly connected in series in such a way that the workpieces (10) run through the individual stations at prescribed clock times and without heat loss. The temperature time variation during the individual working steps is controlled by a central control program in accordance with a prescribed program which has been determined by trial-and-error or through calculation. The installation is particularly suited for the assembly-line, fully-automatic thermo-mechanical working of disk springs, especially those which exhibit greater hardness on the free ends of the disks than in their other areas.

Description

The invention relates to a method according to the preamble of patent claim 1 and a system for carrying out the method according to the preamble of patent claim 4.

To achieve the properties required for the respective intended use, such as hardness, toughness, wear resistance, fatigue strength, fatigue resistance, workpieces made of hardenable metallic materials, in particular iron alloys such as steels, are usually subjected to a tempering process. The tempering process generally comprises several treatment steps, namely a hardening treatment by quenching a workpiece heated to the hardening temperature and a subsequent controlled heat treatment, such as tempering, tempering or holding at a predetermined temperature and / or controlled cooling.

From DE-A1-33 07 041 it is known to clamp a workpiece during the hardness treatment in a hardness press having at least one coolable form and to quench it in the clamped state. The workpiece is then subjected to controlled cooling without intermediate treatment or subjected to controlled heat treatment by tempering and / or isothermal heat treatment in a heatable holding press. This prevents the workpiece from undergoing a change in its shape and / or dimensions during the tempering process, i. H. warps. Since quenching by indirect cooling, i.e. H. is carried out using a coolable tool, in particular through which a coolant flows, the workpiece is not contaminated by the coolant used, e.g. B. salt solutions or oils.

Furthermore, from the publication by Dubeikovskii et al., Metal, Science and Heat Treatment, No. 9/10, Sept./Oct. 1976, pages 769-773, a method for the automated heat treatment of friction disks for tractors and an installation for carrying out the method are known. In the described method, the workpiece, i. H. the friction disc, inductively heated to the quenching temperature, whereby the workpiece is rotated in order to achieve uniform heating, including the peripheral areas. The workpiece is then fed to the quenching device, where it is placed on a cooled magnetic plate and coated with a liquid coolant, e.g. B. oil is sprayed. The magnetic field of the magnetic plate is intended to promote the transformation of the supercooled austenite phase into the desired martensite phase. The next step in the process is to remove the coolant by centrifugation. The quenched and cleaned workpiece is tempered using two heated molds between which the workpiece is clamped. The clamping during the tempering process is necessary in order to correct any changes in shape, in particular undulations, during the hardening treatment to which the workpiece was subjected in the non-clamped state. In addition, the starting device is preceded by a high-frequency induction heater, since the heated forms of the starting device cannot be used to achieve sufficiently uniform heating of the workpiece. Following the tempering treatment, the workpiece is fed to a cooling device which is designed similarly to the quenching device. The workpiece lies on a cooled magnetic plate and is cooled to a temperature of 70 to 90 ° C by spraying with water from above. The workpiece is not clamped during cooling and can therefore be subject to a change in its shape and / or its dimensions.

Neither DE-A1-33 07 041 nor the publication by Dubeikovskii et al. (l. c.) contains any references to the possibility of a locally differentiated heating of the workpiece during the thermomechanical treatment, in particular the heat treatment in the tempering stage. If one tries to manufacture flat workpieces with areas of different hardness with the help of the described methods, one has to determine that this is not possible, since these methods were based on a completely different task. In the manufacture of such workpieces, in particular plate springs for use in the automotive industry, which have lamellae projecting radially inwards from an outer, closed ring part, the end parts of which must have a greater hardness than the other areas of the plate spring, in particular the outer closed ring part So far, one has proceeded in such a way that such workpieces have been subjected to an additional separate treatment after the completion of the hardening process in order to produce areas of different hardness. This was usually done by either producing the areas in which a greater hardness should be achieved with a resistant material, e.g. B. molybdenum, coated or hard chrome-plated or the disc spring for the area of greater hardness subjected to a second complete hardening treatment. Such additional or special treatments are cumbersome and expensive in each case and also involve the risk that the plate spring warps and is therefore unsuitable for the intended use.

The object of the invention is therefore to provide a method and a system which includes a series, fully automatic, low-distortion thermomechanical treatment of areas Allow flat workpieces of different hardness, in particular disc springs of the type mentioned. In particular, the possibility should be created to obtain products with a predetermined, precisely defined structure and the desired properties with less work, time and energy compared to the known methods and without the need for complex and costly special treatments.

The object is achieved according to the invention by the method defined in claim 1 and with the aid of the system defined in claim 4.

Advantageous embodiments of the method and the system are mentioned in the dependent claims.

The method according to claim 1 offers for the first time the possibility of producing flat workpieces with areas of different hardness in one operation and with a previously unknown shape accuracy and quality. The workpieces obtained in this way can be used directly for their intended purpose without any post-treatment and, in terms of their structural structure and their mechanical properties, correspond perfectly to the requirements placed on them.

Of particular advantage is the embodiment according to claim 2, which allows areas of different hardness disc springs made of thin sheet steel with an outer closed ring part, a central opening and with slats extending radially from the ring part against the opening, which in an adjacent to the opening Area to produce a greater hardness compared to the rest of the plate spring.

With this configuration, disc springs can be obtained in one operation, which have a greater hardness at the lamella ends than in the other areas and are characterized by high dimensional accuracy and quality and can be used directly without any further treatment or special treatment. They meet all the requirements placed on them in terms of dimensional accuracy as well as their microstructure and the resulting mechanical properties such as hardness, toughness, wear resistance, mechanical resistance, fatigue strength and fatigue resistance.

The system of the type mentioned at the outset has a total of four treatment stations, namely a heating device for inductive heating of the workpiece as the first treatment station, a hardening press equipped with at least one form through which a coolant flows, as the second treatment station, a starting device as the third treatment station and one with at least one coolable one Form-equipped cooling device as the fourth and last treatment station, all treatment stations being coupled to and controllable by a central program control device. This system is characterized by the fact that the tempering device has a heatable shape, the shape of which corresponds to that of the shaped and hardened workpiece, in such a way that in the area of the shape, direct heat transfer from the heatable shape to the parts of the workpiece protruding into the photo cavity is prevented. It is thereby achieved that these parts are heated to a lower temperature than the other parts of the workpiece and consequently the areas of the workpiece heated to a lower temperature in the finished end product have a greater hardness than its other areas.

The effectiveness of the locally differentiated heating is further improved if a supply device for blowing compressed air is provided in the region of the mold recess.

Particularly good results are achieved by means of the configuration according to claim 6. This configuration allows the locally differentiated heating to be controlled in such a way that an exact adaptation to the metallurgical parameters required to achieve predetermined properties of the end product is achieved.

If one considers the process in its entirety, there are other significant advantages in addition to the possibility of locally differentiated heat treatment, with the aid of which flat workpieces with areas of different hardness are obtained. For example, the fact that the individual treatment steps follow one another directly and the conveying times between the individual treatment stations are only fractions of the dwell times in the individual treatment stations means that the workpiece can be transferred from one treatment station to the next without heat loss. This favors the quality of the end product, which should not be underestimated. In addition, the continuous monitoring of the temperature profile in the individual treatment stations during the entire process sequence and the feeding of the measurement data obtained into a central program control enables the exact temperature-time profile in the individual treatment stations to be set during the entire process sequence in accordance with a predetermined, through tests and / or calculated metallurgical program.

In this way, it is possible to obtain workpieces, in particular disc springs for use in the automotive industry, whose microstructure and thus their mechanical properties, such as hardness, toughness, wear resistance, mechanical resistance, fatigue strength and fatigue resistance, exactly meet the requirements placed on them and this also during long-term use.

• Figur 1 : Blockdiagramm einer Anlage zur serienmässigen thermomechanischen Behandlung von flächigen Werkstücken ; Figur 2: eine Tellerfeder als Beispiel für eine unter Verwendung der anlage herzustellendes Werkstück ;
• Figur 3: die Tellerfeder im Längsschnitt VII-VII der Figur 2 ;
• Figur 4: eine Fördervorrichtung zum Ueberführen von Werkstücken zwischen den Behandlungsstationen, in Ansicht quer zur Förderrichtung ;
• Figur 5 : die Fördervorrichtung nach Figur 4, in Ansicht in Förderrichtung ;
• Figur 6: Blockdiagramm einer anderen Anlage zur serienmässigen thermomechanischen Behandlung von flächigen Werkstücken.

Embodiments of the invention are described below with reference to the drawings; show:

• Figure 1: Block diagram of a system for se standard thermomechanical treatment of flat workpieces; Figure 2: a plate spring as an example of a workpiece to be produced using the system;
• Figure 3: the plate spring in longitudinal section VII-VII of Figure 2;
• FIG. 4: a conveying device for transferring workpieces between the treatment stations, in a view transverse to the conveying direction;
• Figure 5: the conveyor device according to Figure 4, in view in the conveying direction;
• Figure 6: Block diagram of another system for the standard thermomechanical treatment of flat workpieces.

The block diagram in FIG. 1 shows a system which is suitable for hardening flat workpieces with a small thickness and small to medium dimensions.

• eine Erwärmungseinrichtung 2 als erste Behandlungsstation ;
• eine Härtepresse 4 als zweite Behandlungsstation ;
• eine Anlasseinrichtung 6 als dritte Behandlungsstation ;
• eine Kühleinrichtung 8 als vierte Behandlungsstation.

The system has the following essential components:

• a heating device 2 as the first treatment station;
• a hardening press 4 as a second treatment station;
• a starting device 6 as a third treatment station;
• a cooling device 8 as a fourth treatment station.

The heating device 2, the hardening press 4, the tempering device 6 and the cooling device 8 are arranged horizontally next to one another, in such a way that workpieces 10 to be treated are conveyed in the direction of arrows F _{1 '} F ₂ and F ₃ from the first to the fourth treatment station and can be moved into the individual treatment stations from below.

The heating device 2 is designed as a plate inductor 12 with two mutually opposing plates 14 and 16, the plates 14 and / or 16 being equipped with retractable stops 18, for example retractable or fold-out ceramic pins, for holding the workpiece 10. The plates 14 and 16 are energized by means of an oscillating circuit 20. In addition, a sensor 22 is provided for the contactless measurement of the final temperature. The measured values supplied by the sensor 22 are fed into a central process control device.

Furthermore, the heating device 2 can be equipped with a protective gas device 24, indicated by dashed lines, for heating in a protective gas atmosphere.

In addition to the heating device 2, the hardness press 4 is arranged at the same height with a coolable mold 26. This has a first horizontally displaceable molded part 28, which is equipped with a cooling device 30 for indirect cooling, and a second, fixed molded part 32 arranged at the same height, which is equipped with a second cooling device 34 for indirect cooling. In addition, retractable stops, in particular centering mandrels 36, are provided for holding the workpiece 10. The first cooling device 30 and the second cooling device 34 are expediently connected to a common coolant circuit, which can be connected to a control device for regulating the coolant temperature.

The tempering device 6 with a heatable mold 38 is arranged at the same height next to the hardening press 4. This consists of a horizontally displaceable first molded part 40 which can be heated by means of a first heating device 42 and a second molded part 44 which can be heated by means of a second heating device 46. Retractable stops or centering pins 48 are provided to hold the workpiece 10. In order to achieve a locally differentiated heating of the workpiece 10, the second molded part 44 is provided with a recess 50, through which a direct heat transfer is avoided. In addition, a feed device 51 is provided for blowing in compressed air. The first heating device 42 and the second heating device 46 are connected to a control unit 52 for controlling the temperature / time profile.

Following the starting device 6, the cooling device 8 with a coolable mold 56 is arranged at the same height. The structure of this corresponds essentially to the hardness press 4 and is intended to ensure a distortion-free cooling of a molded and tempered workpiece 54 arriving from the starting device 6 in the clamped state and with a controlled temperature / time profile. The coolable mold 56 has a first horizontally displaceable molded part 58 which is equipped with a first cooling device 60 for indirect cooling, and a second molded part 62 which is arranged at the same height and which is equipped with a second cooling device 64 for indirect cooling. In addition, retractable stops or centering pins 66 are provided for holding the workpiece 54. The first cooling device 60 and the second cooling device 64 are expediently connected to a common coolant circuit, which can be connected to a control device for regulating the coolant temperature.

The system is preferably used for the production of workpieces with a small thickness, for example a plate spring 68 according to FIG. 2. The plate spring 68 has an outer closed ring part 70 and a central opening 72, from which radially extending incisions extend as far as the ring part, whereby lamellae 74 extending radially to the opening 72 are formed. As can be seen from FIG. 3, the plate spring has 68 zones of different hardness. For example, the hardness in the ring part 70 and an adjacent area 76 of the fins 74 has a hardness of approximately 42 to 45 HRC and in a area 78 adjacent to the central opening 72 a hardness of approximately 58 to 60 HRC.

• In die erste Behandlungsstation, die Erwärmungseinrichtung 2, die den Platteninduktor 12 enthält, wird jeweils eine Ausstanzen aus Stahlblech mit einer Dicke von 1,5 bis 2,5 mm hergestellte, als Rohling vorliegende Tellerfeder 68 eingebracht. Die Tellerfeder 68 kann zum Beispiel mit Hilfe von Magnetgreifern einem auf einer Auflage, zum Beispiel einem drehbaren Rundtisch, aufgestapelten Vorrat an Rohlingen entnommen und von unten in den Platteninduktor 12 eingefahren werden. Mittels der rücknehmbaren Anschläge 18 wird die Tellerfeder 68 zwischen den Platten 14 und 16 des Platteninduktors gehalten. Dabei sind die Anschläge 18 bevorzugt so ausgebildet, dass die Tellerfeder 68 während des Erwärmens gedreht werden kann. Der Platteninduktor wird mittels des Schwingkreises 20 beispielsweise mit 60 kVA beaufschlagt und bewirkt eine Erwärmung der Tellerfeder 68 auf ihre Austenitisierungstemperatur von 900 bis 1 100 °C. Der Temperaturverlauf bis zum Erreichen der Ausdenitisierungstemperatur wird mittels des Messfühlers 22 überwacht. Der Messfühler 22 ist so ausgebildet, dass er eine berührungsfreie Temperaturmessung erlaubt. Die erhaltenen Messwerte werden in eine zentrale Programmsteuereinrichtung eingegeben und können auf einem Monitor verfolgt und mit dem für ein bestimmtes Gefüge berechneten und/oder durch Versuche ermittelten Verlauf der Erwärmungskurve abgeglichen werden.

The plate spring 68 is produced in the following way:

• In the first treatment station, the heating device 2, which contains the plate inductor 12, a punching out of sheet steel with a thickness of 1.5 to 2.5 mm, which is present as a blank, is introduced. The plate spring 68 can be removed, for example with the aid of magnetic grippers, from a supply of blanks stacked on a support, for example a rotatable rotary table, and inserted into the plate inductor 12 from below. By means of the retractable stops 18, the plate spring 68 is held between the plates 14 and 16 of the plate inductor. The stops 18 are preferably designed such that the plate spring 68 can be rotated during the heating. The plate inductor is acted upon by the resonant circuit 20 with 60 kVA, for example, and heats the plate spring 68 to its austenitizing temperature of 900 to 1100 ° C. The temperature curve until the ausdenitization temperature is reached is monitored by means of the sensor 22. The sensor 22 is designed in such a way that it allows a non-contact temperature measurement. The measured values obtained are entered into a central program control device and can be tracked on a monitor and compared with the course of the heating curve calculated for a specific structure and / or determined by tests.

As soon as the austenitizing temperature has been reached, for which only a few seconds, for example 15 seconds, are required, the plate spring 68 is released by pulling back the retractable stops 18 and transported to the second treatment station, the hardening press 4, by means of a first conveyor device 80 according to FIG. 4 . The plate spring 68 is inserted from below into the indirectly cooled mold 26 of the hardening press 4 and is held there by means of the centering mandrel 36. By horizontally displacing the first molded part 28 in the direction of the second molded part 32, the mold 26 is closed, the plate spring 68 is clamped in and in accordance with the shape of the mold 26 using a pressure of, for example, 6 Mp into the desired shape shown in FIGS. 2 and 3 brought. The flat blank is shaped like a cone. The first molded part 28 is kept at the temperature required for quenching by means of the cooling device 30, as is the second molded part by means of the second cooling device 34. The temperature can be set and maintained in such a way that the two cooling devices are connected to a common one Control device for temperature control equipped coolant circuit can be connected. The temperature to be set in the individual case depends on the mechanical properties to be achieved and thus on the desired structure and can be determined by calculation or by experiment.

By opening the mold 26 and pulling back the centering mandrel 36, the hardened disc spring 68 is released downward and transported to the third treatment station of the starting device 6 by means of a second conveyor device 82, which corresponds to the first, and clamped there in the heatable mold 38. The clamping takes place by horizontal displacement of the first molded part 40, which is heated to the tempering temperature by means of the first heating device 42, in the direction of the second molded part 44, which is heated to the tempering temperature by means of the second heating device 46. A locally differentiated heating of the plate spring 68 is achieved by the recess 50 in the molded part 44, which is arranged in the area 78 adjacent to the central opening 72 at the free ends of the lamellae 74, such that only the area of the ring part 70 and the Adjacent areas 76 are heated directly, while the area 78 is heated exclusively by heat conduction within the plate spring 68. In this case, an even stronger local differentiation of the heating can be achieved if the area 78 is additionally cooled by blowing in compressed air by means of the feed device 51. The required hardness values are reached within a few seconds (accelerated tempering) due to the heating - to around 550 ° C, for example. It is thereby achieved that the plate spring 68 has a higher hardness in the area 78 than in the other areas. The heating devices 42 and 46 are also connected to the control unit 52, which allows a precise setting of the starting temperature, for example in the range from 150 to 600 ° C., and the duration of the starting process. The tempering temperature to be set in individual cases and / or the duration of the tempering process depends on the structure to be achieved and the required mechanical properties and can be determined by tests or by calculation. In this case, the lower the tempering temperature, for example, the greater the hardness. Martensite embrittlement is avoided in the accelerated starting process. With short tempering times of a few seconds at correspondingly higher temperatures, better mechanical properties are achieved. The temperature can be monitored by means of a sensor and the measured values obtained can be fed into a central control device. The temperature / time profile can be monitored by means of a monitor and compared with the profile of the heating curve calculated for a specific structure and / or determined by tests.

The shaped and hardened disc spring 68 is then released by opening the heatable mold 38 and pulling back the centering mandrel 48 and by means of a third conveyor device 84, which corresponds to the first and second conveyor devices, to the fourth treatment lungsstation, the cooling device 8 fed. This is designed in accordance with the hardness press 4. The plate spring 68 supplied by the conveyor device 84 and coming from the starting device is inserted from below into the coolable mold 56 of the cooling device 8 and held there by means of the centering mandrel 66. By horizontal displacement of the first molded part 58 in the direction of the second molded part 62, the mold 56 is closed and the plate spring 68 is clamped and in the clamped state by means of the cooling devices 60 and 64 in accordance with a temperature calculated and / or determined by tests and stored in a central program control device. Cooled time curve. The plate spring 68 is ready for use after cooling and is characterized by a high degree of dimensional accuracy and a uniform structure, so that it does not have to be subjected to any additional treatment steps.

During the entire process, all treatment stations are preferably run through with the same cycle time. The cycle time to be used in the individual case is determined experimentally or mathematically and is set according to the duration of the process which takes the most time, usually the deterrent process in the second treatment station, and the treatment in the other stations is adjusted to the predetermined cycle time. The cycle times can range from a few seconds to a few minutes, depending on the volume of the workpiece.

FIGS. 4 and 5 show the conveyor device 80, which is particularly suitable for moving preferably upright flat workpieces, such as, in particular, plate springs 68 according to FIGS. 2 and 3. The conveyor device 80 contains a holder .86 with a driver 88, on which three grippers 90 are arranged along an arc of a circle whose radius corresponds to that of the plate springs. The three grippers are provided with a material with reduced thermal conductivity at least on the fork-like part interacting with the plate spring. The holder 86 is arranged on a parallelogram guide 92 which has two parallelogram arms 94 which are connected on the one hand via bearings 96 to the holder 86 and on the other hand via shafts 98 to the frame 100 of the system. Set screws 102, 104 for adjusting the end positions of the driver 88 are arranged on the parallelogram arms 94. A drive device 106 is connected to a shaft 98 and is preferably connected to the central program control device.

The driver 88 of the conveyor device executes a curved movement, which in the present case is circular-arc-shaped. The driver drives into a treatment station from below, grips the lower part of a workpiece, for example a plate spring, which can be freely extended downwards after taking back stops in the treatment station, along an arc to the next treatment station and then retracted from below. After setting the stops in the treatment station, the workpiece is held in place and the driver can freely swing back down to the previous treatment station and pick up a new workpiece.

The system can also be designed in such a way that the workpieces are arranged horizontally during the individual treatment steps and not upright as described in the previous example. The horizontal arrangement is particularly recommended for workpieces with larger dimensions, e.g. B. a diameter of approximately 0.5 m or more.

The block diagram in FIG. 6 shows a system which is suitable for hardening flat workpieces with a small thickness.

• eine Beschickungseinrichtung 108 zum Zuführen von Werkstücken ;
• eine Erwärmungseinrichtung 110 als erste Behandlungsstation ;
• eine Härtepresse 112 als zweite Behandlungsstation ;
• eine Anlasseinrichtung 114 als dritte Behandlungsstation ; und
• eine Abführeinrichtung 116 zum Abführen fertiger Werkstücke.

The system has the following essential components:

• a feeder 108 for feeding workpieces;
• a heating device 110 as a first treatment station;
• a hardening press 112 as a second treatment station;
• a starting device 114 as a third treatment station; and
• a removal device 116 for removing finished workpieces.

In this example, the loading device 108, the heating device 110, the hardening press 112, the starting device 114 and the discharge device 116 are arranged vertically one above the other, in such a way that the workpieces pass through the system in free fall.

The loading device 108 has a magazine 118 for receiving the workpieces 120 and is equipped with a pretensioning device 122, by means of which the workpieces 120 are prestressed against an outlet side 124 and can be moved in the direction of a gap-shaped outlet opening 126. This expediently has a gap width which is greater than the thickness of a workpiece 120 but less than twice the thickness of the workpiece 120. Above the outlet opening 126 there is an ejection device 128, by means of which the workpiece 120 can be ejected downwards. Below the outlet opening 126, the heating device 110 is arranged, which is preferably designed as a plate inductor 130 with two mutually opposite plates 132 and 134, the plates 132 and / or 134 for holding the workpiece 120 with retractable stops 136, for. B. retractable or fold-out ceramic pins are equipped.

In addition, the heating device 110 can be equipped with a protective gas device 138, indicated by dashed lines, for heating in a protective gas atmosphere.

Below the heating device 110 is the hardness press 112 with a coolable mold 140 arranged. This has a first horizontally displaceable molded part 142, which is equipped with a first cooling device 144 for indirect cooling, and a second, fixed molded part 146 arranged at the same height, which is equipped with a second cooling device 148 for indirect cooling. There is also a centering mandrel 150 for holding the workpiece 120. The first cooling device 144 and the second cooling device 148 are expediently connected to a common coolant circuit, which can be connected to a control device for regulating the coolant temperature.

The tempering device 114 with a heatable mold 152 is arranged below the hardening press 112. This consists of a horizontally displaceable first molded part 154, which can be heated by means of a first heating device 156, and a second molded part 158, which can be heated by means of a second heating device 160. A centering mandrel 162 is provided for holding the workpiece 120. In order to achieve a locally differentiated heating of the workpiece 120, the second molded part 158 is provided with a recess 164, through which a direct heat transfer is avoided. In addition, a feed device 166 is provided for blowing compressed air. The first heating device 156 and the second heating device 160 are connected to a control unit 168 for controlling the temperature / time profile.

Below the starting device 114, the discharge device 116, for. B. a conveyor 170, preferably a conveyor belt 172, arranged for removing finished workpieces 174. The conveyor belt 172 can simultaneously be designed as a cooling section for the shaped and hardened workpieces 174.

The system is preferably used for the production of workpieces with a small thickness and very small dimensions in the range of a few centimeters.

In general, the thermomechanical treatment is carried out without using a protective gas atmosphere. In special cases, however, it is possible to provide either the first treatment station, that is to say the plate inductor, or the entire system with a protective gas device. Technical nitrogen is particularly suitable as a protective gas.

Reference symbol list

• 2 heating device
• 4 hardness press
• 6 starting device
• 8 cooling device
• 10 workpiece
• 12 plate inductor
• 14 plate
• 16 plate
• 18 retractable stop
• 20 resonant circuit
• 22 sensors
• 24 inert gas device
• 26 coolable form
• 28 1st molded part
• 30 1. Cooling device
• 32 2nd molded part
• 34 2. Cooling device
• 36 retractable stop or centering pin
• 38 heated mold
• 40 1st molded part
• 42 1. Heater
• 44 2nd molded part
• 46 2. Heater
• 48 retractable stop or centering pin
• 50 recess
• 51 Supply device for compressed air
• 52 control unit
• 54 shaped workpiece
• 56 coolable form
• 58 1st molded part
• 60 1. Cooling device
• 62 2nd molded part
• 64 2. Cooling device
• 66 retractable stop or centering pin
• 68 disc spring
• 70 ring part
• 72 central opening
• 74 slats
• 76 area adjacent to the ring part
• 78 area adjacent to the central opening
• 80 1st conveyor
• 82 2. Conveyor device
• 84 3. Conveyor device
• 86 holder
• 88 drivers
• 90 grippers
• 92 Parallelogram guidance
• 94 parallelogram arm
• 96 bearings of 86
• 98 wave
• 100 frames
• 102 set screw
• 104 set screw
• 106 drive device
• 108 loading device
• 110 heating device
• 112 hardness press
• 114 starting device
• 116 discharge device
• 118 magazine
• 120 workpiece
• 122 pre-tensioning device
• 124 exit side
• 126 outlet opening
• 128 ejection device
• 130 plate inductor
• 132 plate
• 134 plate
• 136 retractable stop
• 138 Shielding gas device
• 140 coolable mold
• 142 1st molded part
• 144 1. Cooling device
• 146 2nd molded part
• 148 2. Cooling device
• 150 retractable stop or centering mandrel
• 152 heated mold
• 154 1st molded part
• 156 1. Heater
• 158 2nd molding
• 160 2. Heater
• 162 retractable stop or centering mandrel 164 recess
• 166 Supply device for compressed air
• 168 control unit
• 170 conveyor
• 172 conveyor belt
• 174 shaped workpiece

Claims (6)

1. A method for the serial fully-automatic low- distortion thermomechanical treatment of laminar workpieces, having regions of different hardness, made from hardenable metallic materials, the method having at least four method steps, namely :

Inductive heating of the workpiece to its austenitisation temperature in a heating device as the first treatment station ;

Quenching of the heated workpiece to a predetermined temperature above room temperature in a quenching press, equipped with at least one coolable mould flowed-through by a cooling fluid, as the second treatment station with simultaneous shaping by clamping and application of pressure ;

Tempering of the quenched and shaped workpiece in a tempering device, equipped with at least one heatable mould, as the third treatment station ; and

regulated cooling of the shaped, hardened and tempered workpiece in the clamped state in a cooling device, equipped with at least one coolable mould, as the fourth treatment station,
in which respect the transfer from one treatment station to the next is carried out without loss of heat and in which respect during the entire method cycle the temperature variation in the individual treatment stations is permanently monitored and the measured values obtained are fed to a central programme control and the tem- perature/time variation is adjusted during the entire method cycle in the individual treatment stages by means of the central programme control in accordance with a predetermined metallurgical programme ascertained by experiments and/or mathematically, characterised in that in the third treatment station a locally differentiated heat treatment is carried out, in such a way that the workpiece is heated regionally to different temperatures, in which respect those regions of the workpiece which in the final state are to have a greater hardness than the remaining regions are tempered at a temperature which is lower than the temperature applied to the remaining regions.

2. A method according to claim 1 for the treatment of cup springs (68), having regions of different hardness, made from thin steel sheet with an outer closed ring part (70), a central aperture (72) and with lamellae (74) which extend from the ring part (70) radially towards the aperture (72) and which in a region (78) contiguous to the aperture (72) have a greater hardness in comparison with the remaining part of the cup spring (68), characterised in that the cup spring (68) is heated to tempering temperature in the heatable mould (38) of the tempering device (6), in such a way that the free ends of the lamellae (74) in the region (78) are exposed to a heat treatment deviating from the remaining part of the cup spring (68) and/or compressed air is injected.

3. A method according to claim 2, characterised in that the free ends of the lamellae (74) in the region (78) are allowed to project into a recess (50) of the mould (38), whereby a direct transfer of heat from the mould (38) to the free ends of the lamellae (74) in the region (78) is prevented.

4. An installation for carrying out the method according to one of claims 1 to 3 with a heating device (2) for the inductive heating of the workpiece as the first treatment station, a quenching press (4), equipped with at least one mould (26) flowed-through by a cooling fluid, as the second treatment station, a tempering device (6) as the third treatment station and a cooling device (8), equipped with at least one coolable mould (56), as the fourth treatment station, in which respect the treatment stations (2, 4, 6, 8) are coupled to a central programme control device and are controllable by this, characterised in that the tempering device (6) has a heatable mould (38), the mould recess of which corresponds to that of the hardened and shaped workpiece (54, 68), and which has two mould parts (40, 44), at least one of which is mobile for the opening and closing of the mould (38), and at least one of which is equipped with a heating device (42, 46) and in that it is designed for the locally differentiated heating of the workpiece (54, 68), in which respect the mould parts (40, 44) have at least one recess (50) preventing the direct transfer of heat.

5. An installation according to claim 4, characterised in that a feed mechanism (51) for the injection of compressed air is provided in the region of the recess (50).

6. An installation according to claim 4 or 5, characterised in that the heating device (42, 46) of the tempering device (6) is connected to a control unit (52) for the adjustment of tempering temperature and/or tempering duration.

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