EP2700725B1 - Fixture for hardening a ring shaped workpiece - Google Patents

Description

The invention relates to a fixture for curing a single annular workpiece and a method thereof.

As is known, hardening is applied to metallic workpieces, in particular steel, in order to give them sufficient and / or predetermined hardness and resistance to mechanical stresses, such as static or dynamic deformation by tension, pressure, bending and wear, depending on their specific later use ,

When a workpiece is hardened, it is generally heated to a material-specific hardening temperature, held for a certain time on this material-specific preconditions and then quenched. After quenching usually follows the step of tempering, in which the workpiece is in turn heated to a material and / or hardness-specific temperature and then again cooled to room temperature. During tempering, the hardness decreases with the temperature, whereas, however, the toughness is increased, so that the ductility which is necessary due to an application-specific load is often only guaranteed by the tempering.

From the DE 33 07 041 A1 a method and an apparatus for the standard low-distortion hardening of workpieces is known in which a workpiece in a Hardening press is clamped, quenched by means of a cooled tool and / or by means of a flowing gaseous coolant and subjected to a heat treatment.

From the WO 99/02744 For example, a method and apparatus for heat treatment of steel rings is known in which the inner and outer surfaces of preheated rings are exposed to different streams of cooling medium to achieve different cooling processes on the different surfaces.

From the DE 10 2005 016 535 a receiving device for Ereichen different degrees of hardness of curable workpieces is known, which has a plurality of arranged on two opposite sides of the workpiece modules, which comprise at least one Leitweges systems for supplying cooling media and formed at least one for abutment against the workpiece to be picked up for receiving the workpiece Wall region which is adjacent to a route for indirect cooling of the workpiece on a side facing away from the workpiece, and at least one wall region, on which a route to the male workpiece is open for direct cooling of the workpiece, and the channels channel and / or slot-like and are designed for supplying fluids and / or gases.

From the EP 1 464 711 A1 For example, a method and apparatus for curing hot annular workpieces with a cold quenchant is known in which a plurality of workpieces are batched over a slipped fixed mandrel and exposed to the quenching agent, and the mandrel is ejected after quenching from the workpieces. In order to improve the hardening of the workpieces, it is provided in accordance with this prior art that the workpieces are pressurized in a closed, pressure-tight quenching chamber with pressurized cold gas, and the mandrel is ejected outside the quenching chamber.

The present invention has the object to provide a further improved Fixtur and a method for curing a single annular workpiece, which is a low distortion hardening and thus hardening of an annular workpiece with high precision with gaseous media and without the use of a pressure-tight quenching chamber enable.

The solution according to the invention is already given by a device and a method having the features according to the appended independent claims. Advantageous and / or preferred developments and embodiments are the subject of the dependent claims.

The invention therefore proposes a method for hardening each of a single, annular workpiece, wherein in each case a single, to be hardened annular workpiece is slipped either with its inner opening on a mandrel until the workpiece rests with a first end face on a support or initially placed with a first end face on a support and then a mandrel is inserted into the inner opening of the workpiece. Then one or more Hold-down of one of the first end face opposite side toward the support moved until the or the hold-down on one of the first end face opposing second end face of the workpiece kraftbeaufschlagt rests or rest, and then cold gaseous quenching to the workpiece limiting and opposite each other directed surfaces of the workpiece is supplied and heated quenching is removed, in particular at least to a radially inwardly directed inner surface of the workpiece, which limits the workpiece to the inner opening of the workpiece, and fed to a radially outwardly directed outer surface of the workpiece or at least to the supplied first and second end face and heated quenching agent is removed.

Further, for carrying out the method, the invention proposes a fixture for hardening each of a single, annular workpiece, which comprises a mandrel arranged in the fixture, which is arranged coaxially to the axis of rotation of the workpiece, and through the inner opening during hardening of the annular workpiece extends. The fixture according to the invention additionally has a force application device with a support and one or more hold-downs (s) which are mechanically movable along the axis of rotation, wherein the workpiece rests on the support during curing with a first end face and the hold-down device on a second end face opposite the first end face Stressed force rests on the end face of the workpiece, and moreover routes for supplying cold gaseous quenching to the workpiece delimiting and mutually opposing surfaces of the workpiece and for discharging heated quenching out of the fixture, in particular for supplying cold gaseous quenching agent at least to a radially inwardly directed inner surface of the workpiece, which limits the workpiece toward the inner opening of the workpiece, and to a radially outwardly directed outer surface of the workpiece, and for discharging heated quenching out of the fixture, or at least to the first and second end face and for discharging heated quenching out of the fixture out.

The routes are here either at least partially formed within the mandrel or in the support and in the hold-down.

An essential advantage of the invention can therefore be seen in the fact that the fixture, in contrast to a receiving device which has only on two opposite sides of the workpiece arranged modules with routes is used in addition to the exercise of the necessary mechanical forces, the workpiece by means of the mandrel while hardening around in the form and in addition by means of supports and hold-down is held level. Furthermore, the inventive fixture is used to influence the supply of the gaseous quenching agent. In contrast, for example, to a hardening of a plurality of batch-recorded workpieces is thus a controlled and reproducible flow of the quenching agent for each individual workpiece achievable, resulting in a more uniform quenching and also to a significant reduction in the distortion behavior of each workpiece to be cured leads.

Thus, in particular, the gaseous quenching agent, depending on the specific formation of each individual workpiece to the respective larger area, the workpiece limiting and opposing surfaces can be supplied, which thus leads to a further improved quenching behavior of each workpiece to be cured.

If in this case the annular workpiece is formed such that the thickness of the workpiece is greater than the difference between the outer radius of the workpiece and the radius of the opening, the method and the fixture are expediently designed such that the cold gaseous quenching means at least at the radially inward directed inner surface of the workpiece and to the radially outwardly directed outer surface is supplied. If, however, the annular workpiece is formed such that the thickness of the workpiece is less than the difference between the outer radius of the workpiece and the radius of the opening, the method and the fixture are advantageously designed such that the cold gaseous quenching agent at least to the outer first end face and the outer second end surface is supplied.

Further advantages and features of the invention will become apparent from the following exemplary description of some preferred embodiments with reference to the accompanying drawings.

Fig. 1

eine nicht maßstabsgetreue Skizze einer nicht vom Schutzbereich der Ansprüche umfassten Ausführungsform zum Gasabschrecken eines in einer Fixtur aufgenommenen einzelnen ringförmigen Werkstück durch Umströmen des Werkstücks mit Gas,

Fig. 2

eine nicht maßstabsgetreue Skizze einer Ausführungsform zum Gasabschrecken eines in einer Fixtur aufgenommenen einzelnen ringförmigen Werkstück durch Anströmen des Werkstücks mit Gas mittels Düsenfeld,

Fig. 3

eine nicht maßstabsgetreue Skizze einer nicht vom Schutzbereich der Ansprüche umfassten Ausführungsform einer Fixtur mit einem einzelnen, darin aufgenommenen ringförmigen Werkstück zum Abschrecken des Werkstücks durch Umströmen des Werkstücks mit Gas,

Fig. 4

eine nicht maßstabsgetreue Skizze von Ausführungsformen einer Fixtur mit einem einzelnen, darin aufgenommenen ringförmigen Werkstück zum Abschrecken des Werkstücks durch Anströmen des Werkstücks mit Gas oder mit Gas und dem Gas beigemengten Flüssigkeitstropfen und

Fig. 5

eine nicht maßstabsgetreue Skizze einer weiteren Ausführungsform zum Gasabschrecken eines in einer Fixtur aufgenommenen einzelnen ringförmigen Werkstück durch Anströmen des Werkstücks mit Gas.

In the drawings show:

Fig. 1

a sketch not to scale of an embodiment not covered by the scope of the claims for gas quenching of a single annular workpiece received in a fixture by flowing the workpiece with gas,

Fig. 2

a sketch, not to scale, of an embodiment for gas quenching of a single annular workpiece received in a fixture by flowing the workpiece with gas by means of a nozzle field,

Fig. 3

a sketch not to scale of an embodiment of a fixture not covered by the scope of the claims, having a single annular workpiece received therein for quenching the workpiece by circulating the workpiece with gas,

Fig. 4

a non-scale sketch of embodiments of a fixture with a single, received therein annular workpiece for quenching the workpiece by blowing the workpiece with gas or with gas and the gas added liquid drop and

Fig. 5

a non-scale sketch of a further embodiment for gas quenching of a received in a fixture, a single annular workpiece by flowing the workpiece with gas.

Hereinafter, by way of example, some preferred embodiments according to the invention will be described, wherein first on the FIGS. 1 and 2 Reference is made to FIG Fig. 1 a sketch, not to scale, of a non-inventive gas quench for hardening a single annular workpiece received in a fixture by flowing a workpiece with gas and Fig. 2 a simplified representation of a gas quenching according to the invention for hardening a recorded in a fixture individual annular workpiece by direct flow of a workpiece 3 with gas greatly simplified represent.

Accordingly, for this purpose, a single, annular workpiece 3, which has previously been heated to a material-specific hardening temperature, is received within a fixture and quenched therein for curing. The hot workpiece 3, which may be, for example, a steel comprehensive sliding sleeve or a gear wheel with radially inwardly and / or outwardly extending, not shown in detail in the figures gearing or annular grooves, for example, first with the opening, which is usually extends centrally through the annular workpiece 3, slipped over a mandrel 1 of the fixture until the tool with a aligned in the direction of the axis of the opening first according to FIG. 1 or 2 bottom face 5 rests on a support 2 of the fixture. Alternatively, however, the hot workpiece 3 can first also with a aligned in the direction of the axis of the opening first according to FIG. 1 or 2 lower end face 5 are placed on a support 2 of the fixture and then a mandrel 1 of the fixture in the opening of the workpiece, which usually extends centrally through the annular workpiece 3, are introduced. In this case, the thorn must 1 of the fixture, however, be designed to be movable accordingly, wherein the mandrel is in this case expediently movable in practical implementation of the fixture such that this from the first, according to FIG. 1 or 2 lower end face 5 forth is introduced into the opening of the workpiece.

Subsequently, a holding-down device 4 of the fixture is moved from one side opposite the first end face 5 and parallel to the direction of the axis of the opening in direction "R" of the support 2, until the hold-down device 4 projects on a second end face 6 of the first end face 5 Workpiece 3 rests subjected to force. It should be noted that instead of merely one hold-down device, a hold-down device composed of a plurality of sub-elements or a plurality of hold-down devices may be provided. For reasons of better clarity, however, the following embodiments are described essentially only with reference to a hold-down device. Due to the ring-shaped workpiece 3 are consequently also the outer first end face 5 and the first end face 5 oppositely directed outer second end face 6 of the workpiece 3 annular, wherein expediently both the first end face 5 substantially completely rests on the support 2 and on the essentially complete second end face 6 of the hold-4 rests, alternatively rest the hold-down. The support 2 and the hold-down 4 are therefore expediently also annular. By means of the kraftbeaufschlagt resting on the second end face 6 blank holder 4, the workpiece can thus be kept flat during curing over the entire ring shape. Is the outside diameter of the Dorns 1 further adapted to the diameter of the opening of the workpiece 3, the mandrel 1 on the outside diameter of the workpiece 3 during curing can also keep round in shape. The workpiece is thus fixed in the fixture such that during curing a possible distortion of the workpiece is substantially reduced and in the ideal case substantially any distortion is excluded.

Like that Fig. 1 and 2 can be seen, there is the annular workpiece formed such that its thickness is greater than the difference between the outer radius of the workpiece and the radius of the opening. Alternatively, the ring-shaped workpiece may also be disc-shaped and thus be designed in the context of the invention such that the thickness of the workpiece is less than the difference between the outer radius of the workpiece and the radius of the opening.

Suitably, the quenching behavior of each workpiece to be cured can be further improved if the cold gaseous quenching agent is supplied to at least the respective larger area, the workpiece limiting, opposing surfaces.

For the hardening process itself, after fixing the workpiece 3 according to FIGS. 1 and 2 cold gaseous quenching agent at least to the radially inwardly directed inner surface of the workpiece 3, which delimits the workpiece 3 towards the inner opening or delimits the inner opening of the workpiece 3, and to the radially outwardly directed outer surface of the workpiece 3 as the workpiece delimiting, opposite each other supplied and opposite surfaces and discharged by the cooling process of the workpiece 3 heated quenching agent.

A correspondingly designed fixture for hardening in each case a single, annular workpiece 3 and thus for receiving and fixed holding the workpiece during the hardening process according to the invention thus comprises a mandrel 1, which is arranged coaxially to the axis of rotation of the workpiece 3, and during hardening of the ring-shaped workpiece 3 can extend through the inner opening, as well as a Kraftbeaufschlagungs device with a support 2 and one or more along the axis of rotation mechanically movable hold-down 4, such that the workpiece 3 rests with the first end face 5 on the support 2 during curing and the one or more hold-downs 4 rests on the first end face 5 directed counter to the second end face 6 of the workpiece 3 kraftbeaufschlagt or rest. Depending on the embodiment, the mandrel 1 may be designed to be mechanically movable along the axis of rotation. For supplying the cold gaseous quenching agent to the workpiece 3 limiting, opposing and opposing surfaces and thus according to Fig. 1 and 2 Preferably, at least to the radially inwardly directed inner surface of the workpiece 3, which bounds the inner opening of the workpiece 3, and to the radially outwardly directed outer surface of the workpiece 3 as the workpiece limiting, opposing and opposing surfaces, the fixture also has correspondingly formed Routes to, in the FIGS. 1 and 2 shown with the arrows. In addition, the fixture further includes in The figures not shown in detail routes for dissipating heated quenching out of the fixture, which are in the simplest case outwardly open passages in the fixture. A fixture according to the invention is therefore not gas-tight.

According to the invention, the fixture thus serves to exert the necessary mechanical forces in order to hold the workpiece 3 in the form and even during hardening and to influence the supply of the gaseous quenching agent. Thus, unlike hardening a plurality of batch-picked workpieces, a controlled and reproducible flow of quenchant is achievable for each individual work piece, resulting in more uniform quenching and further significantly reducing the drafting behavior of each work piece to be cured.

For uniform flow around the workpiece 3 with gaseous quenching the routes are also expediently formed in the fixture such that the supply of the gaseous quenching agent initially takes place from below the mandrel 1, as at FIG. 1 and at FIG. 3 showing a sketch of an embodiment of a fixture with a single annular workpiece received therein for quenching the workpiece by flowing the workpiece with gas. Routes formed in the support 2, for example in the form of grooves or other application-specific passages 7, and guide paths formed on the outer surface of the mandrel 1, eg also in the form of grooves or other application-specific regions 8 With reduced outer diameter, the gaseous quenching agent can thus be guided around, for example, both on the radially inner side and on the radially outer sides or surfaces of the workpiece 3, and flow around this. Fig. 3 provides for the gaseous quenching agent to be introduced, for example, via a central bore 13 in the support 2, after which the quenching agent can flow past the mandrel 1, for example through passages 7 formed in the form of grooves in the support, so that the workpiece is not only moved by means of the regions 8 flows around the radially inwardly directed inner surface but also at its radially outwardly directed outer surface.

Like eg Fig. 2 can be seen, the gaseous quenching agent according to the invention at least partially supplied from within the mandrel 1, in particular at least to the radially inwardly directed inner surface of the workpiece 3. Further, on the side of the fixture opposite the feed side of the quench means, passages 9, 9a leading outwardly from the fixture (FIG. Fig. 3 ), in particular passages 9 formed on the hold-down device 4, for example in the form of grooves formed on the hold-down device or other application-specific surface depressions, and for example passages 9a formed on an outer ring of the fixture, can be easily achieved merely by supplying cold gaseous quenching means Gas flow can be adjusted, which both flows around the workpiece substantially completely and beyond after flowing around the workpiece, the thereby heated quenching agent via the passages 9a finally discharges to the outside of the fixture.

Is further within the fixture expediently at least one temperature sensor 10 ( Fig. 3 ) for detecting the temperature on the workpiece 3, which is connected to a control and / or regulating device, not shown, for adjusting the supply of quenching agent based on the temperature on the workpiece, can easily supply the quenching agent, for example with respect to Supply temperature and / or supply amount of the quenching agent, based on the temperature detected on the workpiece 3 set application-specific, in particular regulated.

As further in Fig. 2 and also at Fig. 4 to see which is similar to the Fig. 2 a sketch of an embodiment of a fixture with a single, received therein annular workpiece for quenching the workpiece by flowing the workpiece with gas shows, for supplying the gaseous quenching at least partially from within the mandrel 1 in particular at least to the radially inwardly directed inner surface of the workpiece 3 expedient at least partially also routes 11 may be formed within the mandrel, which also ensures a faster cooling behavior of the workpiece 3.

Are these routes 11 formed such that a radially inwardly directed inner surface of the workpiece 3 can be additionally fed directly and expediently under pressure by radially outwardly directed supply of gaseous quenching agent, at least an equal at least partial descaling at least the direct be effected on the flowed inner surface areas. To this end, the invention provides for these ducts 11 additionally arranged within the mandrel and radially outwardly directed nozzles 12 for direct flow at least the radially inwardly directed inner surface of the workpiece to connect. Such nozzles 12 may be trained in the simplest training in the mandrel 1 corresponding holes. In an expedient development, however, such nozzles arranged in the mandrel can also be components incorporated in the mandrel with a variable opening cross-section, so that by means of these, in particular in connection with at least one temperature sensor 10 arranged in the fixture and on the workpiece 3, via a control and / or connected thereto. or regulating device for adjusting the supply of quenching agent, it is also advantageous to be able to set the pressure of the supplied quenching means for direct impingement by changing the opening cross-section in an application-specific manner. The embodiment according to Fig. 4 are also turn out to the outside of the fixture leading passages 9, 9a to remove the heated during the hardening process quenching away from the workpiece 3 and outwardly from the fixture.

Of the Fig. 4 Furthermore, an advantageous embodiment of the invention can be seen, according to which in training similar to the previously described training with respect to the direct onflow of the inwardly directed inner surface of the workpiece 3, in the fixture also routes 11a and optionally connected thereto nozzles 12a for a direct Inflating at least one radially outwardly directed outer surface of the workpiece 3 are provided, by radially inwardly feeding the gaseous quenching agent under pressure by means of the conduits 11a and the optionally connected nozzles 12a. With respect to the nozzles 12a, the same applies to the nozzles 12 previously described.

In a particularly preferred embodiment, the nozzles 12a are part of a nozzle array 14 connected to the gullies 11a for supplying the gaseous quench, which has a plurality of nozzles directed around the workpiece and directed towards the workpiece for directing at least one outwardly directed outer surface of the nozzle Workpiece has, in particular of such, radially around the workpiece 3 arranged around, radially inwardly directed nozzles 12a for direct flow at least the radially outwardly directed outer surface of the workpiece 3 with the gaseous quenching agent.

In a further preferred embodiment, is the FIG. 4 Furthermore, to remove an embodiment of a fixture for quenching a single, received in the fixture annular workpiece 3, in which this workpiece is quenched by direct flow of gas and the liquid droplets added to the gas. For this purpose, the pressurized gaseous quenching agent is used by admixing drops of a liquid quenchant to the gaseous quenching agent as a carrier medium.

For this purpose, by way of example, the nozzles 12a are further connected to guide paths 15 for supplying liquid quenching agent and also for admixing drops of the liquid liquid quenching agent to the gaseous quenching agent formed as a carrier medium. Also, the nozzles 12 may be connected in a similar or corresponding manner to routes not shown in the figure, to ensure a liquid supply to the admixture of liquid droplets, in which case the nozzles 12 are formed for mixing drops of liquid quenching agent. Advantageously, the above-described control and / or regulating device is also designed for setting, and thus in particular for controlling, the liquid droplets to be added and connected to the guide paths 15 and / or nozzles for their adjustment.

For discharging the liquid droplet added to the gas from the fixture after the workpiece 3 has flowed on, the fixture may in turn be formed with suitably arranged apertures 16, e.g. can be arranged in a simple design in the central bore 13 in the support 2.

Fig. 5 shows a sketch of a further embodiment for gas quenching a recorded in a fixture single annular workpiece 3 by flowing the workpiece with gas, in which the annular workpiece 3 is disc-shaped and thus formed such that the thickness of the workpiece is less than the difference between the outer radius of the workpiece and the radius of the opening.

For the hardening process itself, thus, after fixing the workpiece 3 according to FIG. 5 cold gaseous Quenching agent preferably at least fed to the axially aligned end faces 5 and 6 as the workpiece limiting, opposing and opposing surfaces and discharged by the cooling process of the workpiece 3 heated quenching agent.

In a modification to the fixtures described above, the fixture has Fig. 5 according to modified trained routes for supplying the cold gaseous quenching to the workpiece 3 limiting, opposing and opposing surfaces and thus according to Fig. 5 preferably at least on the outer, but axially aligned end faces 5 and 6.

The routes are appropriate for this example according to Fig. 5 formed in the fixture such that the supply of the gaseous quenching means from below via formed in the support 2 routes 11b, for example in the form of channels or other application-specific passages, and from above via formed in the hold-4 guides 11c, eg also in shape can be made of channels or other application-specific passages. Thus, for example, first directly the axially aligned end faces 5 and 6 are flown. An expedient embodiment of the invention further provides that the gaseous quenching agent can flow radially outwards through radially outwardly and inwardly leading passages 9b, for example in the form of passages formed as grooves in the support and in the downholder, past the workpiece can flow inwards and over additional axially leading passages 9c in the mandrel 1, for example in the form of grooves formed in the mandrel 1 or other Passages on the workpiece inside and then can flow axially outward.

Like eg Fig. 5 can thus be adjusted in a simple manner only by supplying cold gaseous quenching means thus a gas flow, with which the workpiece first at least at the axially aligned end faces 5 and 6 as the workpiece limiting, opposing surfaces directly flows, the workpiece thereupon flows around substantially completely and in addition, after flowing around the workpiece, the heated quenching agent is finally discharged through the passages to the outside of the fixture.

Here, too, an at least partial descaling of at least the directly flowed surface areas of the end faces 5 and 6 can consequently be effected at the same time. In the context of the invention, also to the routes 11b and 11c additional, in turn directed towards the workpiece at Fig. 5 However, for reasons of clarity not shown nozzles connected. Such nozzles can be in the simplest training in the support and / or in the downholder corresponding holes formed or components with variable opening cross-section, so that by means of these, in particular in connection with at least one, in the fixture and on the workpiece 3, but at Fig. 5 not shown temperature sensor via an attached control and / or regulating device for adjusting the supply of quenching agent and the pressure of the supplied quenching agent for direct flow can be adjusted application-specific by changing the opening cross-section.

In a particularly preferred embodiment, such nozzles may be part of a connected to the routes for supplying the gaseous quenching nozzle array, which a plurality of arranged around the workpiece around, directed towards the workpiece nozzles for direct flow of outwardly facing surfaces of the workpiece and So according to Fig. 5 at least the end faces 5 and 6 has. Also, in such embodiments, drops of a liquid quenchant may in turn be added to the gaseous quenching agent supplied under pressure.

For discharging the gas added to the liquid drop from the fixture after the flow of the workpiece 3, for example, according to Fig. 5 arranged passages 9b and 9c are used.

The invention described with reference to various useful embodiments thus allows a quenching of annular, to disc-shaped items in a fixture, the flow control and media for quenching can be adapted to the individual workpiece geometry and in addition to pure gaseous quenching agents by admixing liquid droplets and 2-phases Mixtures can be used for deterrence application. In addition, the invention allows in particular in training the direct flow self-cleaning of the fixture itself, so that this extremely quickly be used again for the next hardening process of another workpiece.

In addition, in the fixture in a further development of the above-described embodiments, at least one wall area formed for abutment with the male workpiece 3 may be provided, which adjoins a route on a side remote from the workpiece 3, for increased cooling of the tool while indirect cooling of the workpiece 3 to obtain and thus thus also allow a relation to the workpiece again increased heat removal during curing. For reasons of clarity, however, this is not shown in the figures.

LIST OF REFERENCE NUMBERS

1

Mandrel;

2

In stock;

3

annular workpiece;

4

Stripper plate;

5

first end face of the workpiece;

6

second end face of the workpiece;

7

passages;

8th

Areas of the mandrel with reduced outside diameter;

9, 9a, 9b, 9c

Passages;

10

temperature sensor;

11

Routes within the spine;

11a

Routes for flowing radially outwardly directed surfaces of the workpiece;

11b, 11c

Routes for flowing axially aligned surfaces of the workpiece;

12,12a

nozzles;

13

Hole in the overlay;

14

Nozzle array;

15

Hydration;

16

Passage for the discharge of liquid

R

Moving direction;

Claims (10)

1. Fixture for hardening one individual annular workpiece (3) at a time,
   comprising

   - a mandrel (1) which is disposed in the fixture and is disposed coaxially to the axis of rotation of the workpiece (3) and, during hardening of the annular workpiece (3), extends through the inner opening thereof,

   - a force-application device with a support (2) and one or a plurality of hold-down devices (4) which can move mechanically along the axis of rotation, wherein, during hardening, the workpiece (3) lies with a first end surface on the support (2), and the hold-down device(s) (4) lie(s), under the application of force, on a second end surface of the workpiece (3) directed oppositely to the first end surface, and

   - passageways for supplying cold gaseous quenchant to surfaces of the workpiece (3), which define the workpiece (3) and are directed oppositely to each other, and for discharging heated quenchant out of the fixture, characterised in that the passageways are either:

   - formed at least partially within the mandrel, wherein radially outwardly directed nozzles, which are disposed within the mandrel, for providing a direct flow of the gaseous quenchant at least on the radially inwardly directed inner surfaces of the workpiece (3), are attached to the passageways, or

   - formed in the support (2) and in the hold-down device (4), wherein nozzles, which are formed in the support (2) and in the hold-down device (4), for providing a direct flow of the gaseous quenchant on the axially orientated end surfaces (5, 6) of the workpiece (3), are attached to the passageways.
2. Fixture as claimed in claim 1, characterised in that

   - passageways for supplying cold gaseous quenchant are formed at least for supplying cold gaseous quenchant to a radially inwardly directed inner surface of the workpiece (3), which defines the workpiece (3) towards the inner opening, and to a radially outwardly directed outer surface of the workpiece (3), or are formed at least for supplying cold gaseous quenchant to the end surfaces (5, 6) of the workpiece (3).
3. Fixture as claimed in claim 1 or 2, further characterised by

   - a nozzle array, which is attached to the passageways for supplying the gaseous quenchant and has a multiplicity of nozzles, which are disposed around the workpiece (3) and directed in the direction towards the workpiece (3), for providing a direct flow of the gaseous quenchant at least on outwardly directed surfaces of the workpiece (3).
4. Fixture as claimed in claim 3, characterised in that

   - the nozzles are further attached to passageways for supplying liquid quenchant and are formed to mix droplets of the liquid quenchant into the gaseous quenchant as a carrier medium.
5. Fixture as claimed in any one of the preceding claims, further characterised in that

   - at least one temperature sensor for detecting the temperature at the workpiece is disposed within the fixture, wherein the temperature sensor is attached to a control and/or regulating device for adjusting the supply of quenchant based on the temperature at the workpiece.
6. Method for hardening one individual annular workpiece (3) at a time,
   comprising the following steps:

   - either imposing an individual annular workpiece (3) to be hardened with the opening thereof over a mandrel (1) until the workpiece lies with a first end surface on a support (2), or placing an individual annular workpiece (3) to be hardened with a first end surface onto a support (2) and subsequently introducing a mandrel (1) into the inner opening of the workpiece,

   - moving one or a plurality of hold-down devices (4) from a side, which is directed oppositely to the first end surface, in the direction of the support (2) until the hold-down device(s) lie(s), under the application of force, on a second end surface of the workpiece (3), which is directed oppositely to the first end surface, and

   - supplying cold gaseous quenchant at least to surfaces of the workpiece (3) which define the workpiece (3) and are directed oppositely to each other,

   - and discharging heated quenchant,

   characterised in that the gaseous quenchant is either:

   - at least partially supplied from inside the mandrel (1), wherein at least the radially inwardly directed inner surfaces of the workpiece (3) receive a flow directly on them through a radially outwardly directed supply of the gaseous quenchant under pressure, or

   - supplied from inside the support (2) and from inside the hold-down device (4),

   wherein the gaseous quenchant flows under pressure directly against the axially orientated end surfaces (5, 6) of the workpiece (3).
7. Method as claimed in claim 6, further characterised in that in order to supply cold gaseous quenchant, gaseous quenchant is supplied at least onto radially inwardly directed inner surfaces of the workpiece (3), which define the workpiece (3) towards the inner opening, and onto radially outwardly directed outer surfaces of the workpiece (3), or
   gaseous quenchant is supplied at least onto the axially orientated end surfaces of the workpiece (3).
8. Method as claimed in claim 6 or 7, further characterised by

   - providing a direct flow at least on outwardly directed surfaces of the workpiece (3), specifically through the supply of gaseous quenchant under pressure directed from the outside in the direction of the workpiece (3).
9. Method as claimed in claim 8, further characterised by

   - using the gaseous quenchant supplied under pressure as a carrier medium by mixing droplets of a liquid quenchant into the gaseous quenchant.
10. Method as claimed in any one of the preceding claims 6 to 9, further characterised by

    - detecting the temperature at the workpiece and adjusting the supply of quenchant based on the temperature detected at the workpiece.

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