EP1954997B1 - Method and apparatus for heating steel components in a continuous furnace - Google Patents

Description

The invention relates to a method for heating steel components and a device therefor.

It is known to heat steel components to the so-called austenitizing temperature and then harden by frightening. So-called hardness ovens are known for heating to the coagulation temperature, in which the components are inserted and heated accordingly and then removed.

Since the beginning of the 90s, not only machine parts made of steel, such. B. shafts or bearings hardened, but also body parts. This procedure is also called press-hardening steels (PHS). In this technology, to achieve body parts of high strength, a steel plate is heated to the austenitizing temperature and then formed in a mold while rapidly cooled, so that the known hardening effect occurs. By this hardening process, the strength of the body material increases up to z. B. 1,500 MPa. Due to this maximum strength of the material, it has become possible to significantly increase the accident safety of modern vehicles while maintaining the weight of the body. Heretofore, continuous ovens, and in particular roller ovens in which the blanks or preformed parts have been heated, have been used to heat such steel blanks. Since at these temperatures, a significant oxidation on the surface of the components (scaling) occurs, such hardening or heating ovens are usually operated with inert gas.

It is also known to form boards or preformed components with a coating of aluminum or an alloy which consists in about half of aluminum or zinc. Under certain circumstances, the protective gas atmosphere may be omitted in such coatings.

For heating body parts currently running furnaces such as roller kilns but also rotary kilns are used in which the components remain for a long time. Subsequently, the body parts are transported to presses and brought there in the desired shape.

The existing ovens have the disadvantage that the transport system is mounted inside the oven and therefore very susceptible to failure. The maintenance of the transport system can only be done when the stove has cooled down. In addition, the position of the body parts is not fixed and it comes during transport through the oven to positional movements of the parts, so that the parts must first be repositioned when leaving the oven to be finally removed and transported to the press. The disadvantage here is that the parts that are not properly and cleanly positioned cool down quickly during repositioning. In order to compensate for these heat losses, the components in the furnace are heated from the outset to temperatures significantly above those necessary for press hardening would. The temperature required for press hardening is usually 930 ° C.

The fact that all parts are heated to higher temperatures than necessary, but only a part of the parts must be repositioned, get parts of different temperatures in the forming tools. However, different temperatures also mean that the hardnesses achieved are not uniform and there are fluctuations here. In addition, this means that components of different starting temperatures may also have different final temperatures, so that it can also lead to a delay.

In addition, it is disadvantageous in the case of conventional ovens that product carriers weighing more than 60 kg are used. This carrier run after heating the body part of the oven and are transported back outside the oven to the entrance, where then again a new part can be placed on these carriers. During discharge, return and intake, the carrier loses up to 200 ° C. This heat loss must be compensated in the oven again, d. H. The stove must not only heat the body parts, but also the carriers, which costs additional energy.

Another disadvantage of known roller hearth furnaces is that roller hearth furnaces are limited in their width. Since the rollers are made of ceramic or heat-resistant steel, it comes due to the influence of heat at a large width of the furnace to deflections which can not be tolerated in the present case. In addition, this leads to load change damage to the rollers.

The object of the invention is to provide a method with the steel components and in particular a press hardening to be subjected Sheet steel components can be heated quickly, effectively and inexpensively, the product quality is evened out and energy is saved.

The object is achieved by a method according to claim 1.

Advantageous Weiterbildungs.en are subclaims.

It is a further object to provide an apparatus for carrying out the method. This object is achieved with the features of claim 5. Advantageous further developments are characterized in the claims dependent thereon.

The inventive method provides to provide in a Härtungsoffen a first transport device, which transported by defined recordings, which pass through the oven from the entrance to the exit, the parts absolutely positionally accurate and accurate position through the oven.

The inventive method also provides to hand over the parts of the kiln outlet to a second transport device, which takes the parts of the first transport device in precise position and with high speed from the oven position or exact position leads out and at a transfer station of a corresponding transfer device for inserting in a press or a mold for press hardening passes.

In a further advantageous embodiment, a third transport device is provided, which introduces the components at very high speed in the furnace entrance area from the outside into the furnace and passes in precise position to the first transport device or receiving the first transport device.

The method also provides that the second and / or third transport device leads the parts to be hardened by a respective O-feneingangs- and furnace exit lock, which is opened only for the moment of passage of the part and then immediately closed. Due to the high speed of delivery or execution in or out of the oven, the locks are open only for a very short period of time, so that the energy loss is low.

The inventive method further provides that the components to be cured, such as blanks or preformed or already final molded component, are applied to carrier specific to the respective part and transported with the transport devices. However, the carriers are only partially carried out in the actual furnace, the largest part is performed outside the furnace, wherein for the positionally accurate transport through the oven corresponding corresponding receiving means are provided, in which the receiving means of the first transport means, the second transport means and possibly the third Transport device can intervene. The intervention or the coupling of the carrier with the transport means takes place outside of the furnace. Likewise the leadership of the carriers.

In the method according to the invention it is advantageous that possibly high inlet and outlet speeds from the oven and the positionally accurate transport of the parts, the parts lose less heat and therefore need not be heated as high as in the prior art. Due to the precise transport and the low heat loss, all parts in the pressing process have almost the same temperatures whereby homogeneous material properties throughout the production can be achieved.

The fact that the carriers are warmed up only to a small extent and in addition locks are provided and the heat that emerges from the oven as heat loss is kept low. As a result, the process can be carried out energy-optimized.

The device according to the invention is an oven having a furnace space. At least one longitudinal slot is arranged in the furnace chamber floor, wherein a transport space or transport area is arranged below the furnace bottom. In the transport area, at least one transport chain or a transport belt is arranged below the furnace space, which is located below the slot such that the upper run of the chain moves along the slot and the lower run of the chain runs back.

In order to avoid heat escaping from the slot, in particular by convection and radiation or the entry of air, the slot preferably has a seal. The seal may in the simplest case consist of brush-like strips which protrude with tight fibers of a heat-resistant plastic such as PTFE and / or metal fibers and / or glass fibers and / or ceramic fibers of a slot defining edge in the slot. In a further advantageous embodiment, the slot 42 is sealed from both of the slot defining surfaces with Teflon lips, which preferably have an overlap region. In addition, it is possible to provide along the slot a plurality of metal fins, which are pivoted parallel to the bottom wall of the oven and perpendicular to the slot spring loaded over the slot. Both the brush fibers and the plastic flaps, as well as the spring-loaded metal fins, become sideways from a supporting column of the advancing carrier pressed or pivoted and reach after passing through the support column back into the region of the slot, so that a reliable Abschotten against heat and / or false air is achieved. The foreclosure can also be done through an air curtain.

The Umlenksterne or pulleys of the chain are arranged in the region of a furnace beginning or a lock area. On the chain thorns or projections are provided at regular intervals. In the field of Umlenksterne or pulleys of the chain or chains, when several chains are arranged side by side, are aligned with the direction of movement of the chain aligned linear drives to the furnace entrance or to the furnace exit. The linear drives each have a transducer which has a mandrel or a projection in the same way as the chain. This mandrel or protrusion is also formed facing the furnace bottom or pointing upwards, however, the mandrel or the projection of the linear drive is provided from and retractable.

For example, the mandrel is pneumatically or hydraulically actuated. For the transport of parts carriers are provided, which are formed, for example, flat plate-like. On the underside, these flat plate-like carriers have at least one recess, which can engage a mandrel of the linear drive and / or the conveyor chain. The carriers are guided laterally in u-profiles or in corresponding slide rails or the like, so that they are pushed along these slide rails or u-profiles by means of engaging in their underside thorns. With a support arm extending upwardly away from the chain and away from the plate, these carriers pass through the slots of the furnace, releasably securing a receiver for a part to be hardened to a free end of the support arm projecting into the furnace is. The pickup for the part can be replaced depending on the part shape and has, for example, a flat contour on which rests the part, but can also be incorporated in parts in the already a hole pattern only have branched support arms, which engage in the respective holes from below and allow such a good heating of the component. The furnace or the transducer and the support column are dimensioned so that the component to be heated has a minimum distance of 200 mm from all furnace walls. Preferably, the bottom wall of the furnace is made thicker than the other walls to minimize the heat losses from the slot by radiation and convection. With a wall thickness in the oven of, for example, 200 mm, the bottom has a thickness of 300 mm.

For example, the plate-like component of the carrier has on the underside three recesses for the spikes or projections which are arranged one behind the other in the conveying direction. To introduce such a carrier in a corresponding oven, the carrier is fully automatically placed on a first mandrel of a linear drive to push the carrier into the oven. The linear drive is controlled such that it at a certain time zuschiebt the carrier or the plate in the u-profiles or slides on a furnace entrance lock, for example, consists of known per se two successively arranged gates.

If the carrier passes through a certain area of the oven entrance, this area being detected, for example, by sensors arranged in the slide rails, the first oven door opens and closes after passing through this area. The carrier is now guided through the intermediate lock until it passes through another area, which leads to an opening of the inner lock.

This lock then also opens and the linear drive pushes the carrier through this area. The cold control is carried out such that the carrier is positioned in the region of a first Umlenksterns or a first guide roller of the conveyor chain, when a corresponding mandrel or projection of the conveyor chain is guided around the conveyor star around upwards.

This mandrel or projection then engages in the central recess, during which time the linear drive has already lowered its projection and is moved back to its starting position and there receives and promotes the next carrier. The carrier is then guided along the slide rails or U-profiles led laterally through the oven, being pushed by the projection of the conveyor chain.

At the end of the conveyor chain, the conveyor projection of the conveyor chain passes from the recess in the carrier, wherein timed and possibly simultaneously engages a mandrel in the third front in the conveying direction recess of the plate and the associated linear drive pulls the carrier out of the oven. Here, the carrier is still performed in u-profiles or lateral guide rails, in the same way a control of the oven lock takes place at the outlet of the furnace, as at the entrance.

Of course, also oven locks can be used with only a single gate. The linear drives at the beginning and at the end of the furnace are able to accelerate the beams and the parts lying on them very strong and out of the furnace at a very high speed.

Due to the fact that the carriers are guided in position and exact position in the U-profiles or slide rails, and in addition the delivery mandrel or projection of the linear drives but also the conveyor chain precisely determines the pass-through position, the carrier and the parts arrive in position accurately from the furnace. Once the parts or the carriers have come out of the oven, the parts can be removed and fed into a press. The carriers are removed from the corresponding guide rail and automatically returned under or over the furnace to the furnace entrance and there re-inserted into the rails and conveyed by the linear drive.

Instead of a conveyor chain and two parallel conveyor chains can be used with synchronous drive. It is advantageous that the respective linear drives can drive between the chains to pass or take over the carrier. The intervention means such. B. cams run parallel to each other on each chain, so that two engagement means are present attacking the both sides of a central region on the carrier or corresponding engagement means. The linear drives engage with their engagement means in preferably a single engagement means in the transverse center region of the carrier between the engagement means for the chain cams.

Although the carrier is removed from the oven and introduced back into the oven at the furnace entrance, but in the transport system according to the invention only a fraction of the carrier is heated at all, so that the heat loss is considerably lower than in the prior art.

The invention has been explained for a conveyor chain, a slot and a single overhead part. Nevertheless, it is It is also possible to run two or more conveyor chains parallel under the oven and provide a slot for each conveyor chain. This makes it possible to promote a corresponding multiplied number of parts through the oven and then to press. On the other hand, it is also possible to synchronize the conveyor chain and the linear drives with respect to their movement and, for example, hang individual large parts on two or more carriers and lead through the oven.

In addition to the described conveyor system, of course, other conveyor systems are conceivable. Thus, the conveyor chain under the carrier can also attack at lateral areas of the carrier adjacent to the conveyor or slide rails or u-profiles in corresponding recesses. For this purpose, for example, the carrier has only one recess for the two linear drives in the center of the length. In addition, in this embodiment, instead of a chain with two transversely arranged parallel to the conveying direction projections or spikes and two conveyor chains are used whose movement are synchronized so that the linear drive can promote in the area between the two conveyor stars or pulleys to a safe To ensure handover.

In addition, it is also possible that the plate-like components of the carrier laterally beyond the U-profile protruding projections has in which engage the spikes or projections of the chain meshing. For this purpose, the guide rails in the side region of the plate-like components are then formed either as U-profiles with an open bottom or only as an L-shaped support rail, which ensures the lateral guidance of the plates with a raised edge, but does not overlap the plates upwards.

In addition, it is also possible that the spikes of the conveyor chain move the plate-like components under the oven. Do not engage behind lateral projections or engage in recesses below, but only come up behind the rear transverse edge of a plate, attack the rear transverse edge and so the Push plate through the oven. Should be necessary for maintenance reasons, a return promotion of the plates, this is also no problem, because the thorns of a returning chain then attack accordingly at the front transverse edge.

Moreover, it is only essential for the device according to the invention that the carriers are conveyed with a linear drive and a relatively high speed positionally accurate in the oven, with a corresponding transport device accurately transported through the oven and at the end of the oven with a linear drive at high speed positionally accurate be conveyed out of the oven and positioned accurately positioned at a transfer station. Furthermore, the entire transport device is arranged in the non-critical temperature range.

In addition, it is advantageous in the invention when the transport system is not disposed within the furnace but below a furnace bottom, so that only small, the components receiving carrier protrudes through a bottom slot in the oven, but the rest of the carrier out of the oven becomes.

The linear drives can be conventional spindle drives, pneumatic drives or hydraulic drives. Decisive for use in the invention is a positional and precise path control. The linear drives can therefore instead Of engagement means also have end grippers, which grip the carrier at one edge.

The spikes or conveyor projections on the chains are arranged for example at intervals of 200 mm, but it is also possible any other distance in the conveying direction, which is set to the corresponding carrier.

According to the invention, of course, also toothed belt, V-belt or all other known types of belts can be used instead of chains.

Instead of a chain, belt or other drive is performed with a top and bottom strand, it is of course also conceivable to perform the promotion in the field of furnace bottom with a spindle drive, pneumatic or hydraulic drive.

Of course, it is also possible to use a single linear drive, which promotes different speeds in the different areas of the furnace. It is possible in particular in aggregates in which formats are to be heated in which either due to inductive heating heating quickly or in which a particularly high number of pieces does not have to be achieved or which are heated very quickly due to their small size.

Such fast insertion times and extension times of the carrier or of components can not be achieved in the prior art with roller hearth furnaces. On the one hand, it is impossible to achieve a rapid introduction with roller hearth furnaces, because the conveying rollers have a much low frictional resistance for generating the acceleration. Secondly, it is not possible to have different roller speeds within a roller conveyor As a result, in the areas in which the component passes from faster rollers to slower rollers, the component would be moved in an uncontrolled manner. The same happens at the transfer point from slower roles to faster roles. Basically, it must be pointed out again that in roller hearth furnaces a really positional and positionally accurate promotion is not possible. However, such positional and positionally accurate promotion as in the invention is also necessary because at the end of the heating of the second transport device, the part is usually removed by robots. It is advantageous in the invention that in a servo-driven linear drive in a simple manner, a control link between the linear drive or the position of the component and a robot can be made, so that a "flying," acceptance by the robot is readily possible ,

In contrast to width-limited roller hearth furnaces, the furnace according to the invention can have any desired width. It is therefore possible to provide any number of slots and also provide from below access or manholes for entering the oven space.

The method and the device according to the invention will be explained by way of example with reference to an embodiment of the invention with reference to the accompanying drawings.

Figur 1:

stark schematisiert die erfindungsgemäße Vorrichtung in einer seitlichen teilgeschnittenen Ansicht;

Figur 2:

stark schematisiert die Transportvorrichtung der Erfindung in einer Draufsicht;

Figur 3:

stark schematisiert die erfindungsgemäße Vorrichtung in einem Übergabebereich zwischen einer ersten Transporteinrichtung und einer zweiten Transporteinrichtung;

Figur 4:

den erfindungsgemäßen Teileträger in einer Ansicht von unten;

Figur 5:

einen Längsschnitt durch den Teileträger im Bereich eines Eingriffsmittel für ein korrespondierendes Eingriffsmittel eines Linearantriebes;

Figur 6:

den Träger nach Figur 5 in einer weiteren teilgeschnittenen Ansicht zeigend ein Eingriffsmittel für ein korrespondierendes Eingriffsmittel eines Ketten- oder Riemenantriebs.

It shows:

FIG. 1:

strongly schematized the device according to the invention in a side partially sectioned view;

FIG. 2:

highly schematic of the transport device of the invention in a plan view;

FIG. 3:

highly schematically the device according to the invention in a transfer area between a first transport device and a second transport device;

FIG. 4:

the parts carrier according to the invention in a view from below;

FIG. 5:

a longitudinal section through the parts carrier in the region of an engagement means for a corresponding engagement means of a linear drive;

FIG. 6:

the carrier after FIG. 5 in a further partially sectioned view showing an engagement means for a corresponding engagement means of a chain or belt drive.

The device 1 according to the invention for heating components 2 comprises a continuous furnace 3 with a transport device 4. The furnace 3 has a kiln inlet 5, a heating zone 6 and a kiln outlet 7. The kiln inlet 5 and the kiln outlet 7 are each from the region 6 through a lock door 8 , 9 separated. In addition, the oven inlet 5 and the oven outlet 7 are separated to the outside against the atmosphere, each with an oven door 10, 11.

Alternatively, only the furnace gates 10, 11 or the lock doors 8, 9 may be present.

Below the actual furnace 3, the transport device 4 is arranged. The transport device 4 comprises at least below the furnace 3 and below the heating area 6 of the furnace 3 a belt or chain conveyor 12 as the first transport device. The belt or chain conveyor 12 has at least one chain 12a or a belt 12a with an upper run 13 and a lower run 14, the upper run 13 and the lower run 14 are guided around respective pulleys or sprockets 15, 16. The belt or chain transport device 12 has, in particular, two parallel chains or belts 12a, 12b which are arranged parallel to one another, with one lower strand and upper strand 13a, 13b, 14a, 14b being present for each of the transport devices 12a, 12b. The corresponding gear and / or pulleys 15a, 15b, 16a, 16b are preferably each on a common drive shaft 17 (FIG. FIG. 3 ) rotatably driven coupled. Upper strand 13a, 13b and lower strand 14a, 14b of the chains 12a, 12b or the chains or belts 12a, 12b themselves have outwardly, ie away from the wheels 15, 16 facing transport cams, transport projections or transport thorns 18. These transport cams, thorns or projections protrude outwardly from the chains 12 and belts 12 and serve as engagement means 18.

In addition, at least one linear transport device 20 is present as a second transport device. The linear transport device 20 is a linear drive which is movable hydraulically, pneumatically, electromagnetically or via spindle drives. The direction of movement (arrow 21) of the linear drive 20 runs parallel to the advancing direction 22 of the transport device 4, while the transport device 4, however, only runs in one direction during operation. The direction of movement of the linear drive 20 or the linear drive device 20 is reversing.

The linear drive device 20 has an in the same direction to the cam 18 protruding or movable cam or mandrel 24, which is arranged on the linear transport device 20 and retractable. The linear drive device 20 can be moved above the axis 17 and between the two chains 12a, 12b or belts 12a, 12b or pulleys 16a, 16b.

In addition, the first linear drive device 20 opposite a second, similarly designed linear drive device 25 may be present as a third transport device. In this case, the linear drive device 20 is preferably located below the oven outlet region 7 and the linear drive device 25 below the oven inlet region 5. The linear drives 20, 25 are preferably driven by servo motors.

To pass through hardened parts through the furnace 3 supporting elements 30 are present. The support elements 30 have a flat plate-like foot 31 which has a front edge 32 in the direction of movement 22, a rear edge 33 and right and left side edges 34. Further, the foot has a bottom 35 and a top 36. Centrally in the middle of the top 36 of the foot 31, a support column 37 is present. The support column 37 extends away from the foot 31.

With the longitudinal edges 34 and this surrounding the foot 31 is guided in guide rails 40 which extend from the kiln inlet to the furnace outlet. The guide rails 40 extend above the transport means 4, 20, 25 and below a furnace bottom 41 and guide the foot 31 both in the vertical direction and in the horizontal transverse direction to the direction of movement 22. At its side edges 34, the support member may have projecting support rollers which an axis are rotatably mounted, which runs parallel to the plate plane and are guided rolling in the guide rails. Furthermore, guide rollers or balls may be present, which are rotatably mounted about an axis perpendicular to the plate plane axis and cause a guide transversely to the conveying direction.

In the furnace bottom 41, a slot 42 is provided which is formed continuously from the kiln inlet to the kiln outlet. Through the slot 42, the support column 37 is guided, which hineinerstreckt a piece in the Ofenraüm 6. At a free end of the support column 37, a holding device 43 for the workpiece 2 and the aufheizenden part 2 is provided. The slot is as narrow as possible, but at a distance from the support column 37th

The support element 30 is designed for transport in the direction of the furnace throughflow direction 22 by the devices 4, 20, 25. For this purpose, the foot 31 has in its underside 35 engagement means 50 for cooperation with corresponding engagement means of the chain (s) 12 and belt 12 of the transport device 4. In addition, the foot has lower side engaging means 51 in its underside which correspond with engagement means of the linear drive means 20, 25 ,

If the engagement means of the transport device 4 are cams, spikes or protrusions 18 projecting from the chains, the engagement means 50 are formed as parallel grooves whose spacing corresponds to the spacing of the cams 18 of the transport device 4 running parallel along the advancing direction 22. The grooves 50 are open at a rear end face 33 of the foot 31 and closing adjacent to the front edge 32, each with a groove bottom 52 from.

Is the engaging means of the linear drives a projecting, extendable cam or projection 24 is the corresponding Engagement part means in the bottom 35 of the foot 31 a corresponding, positive recess 51st

In order to achieve exact and accurate positioning, it is preferred ( FIG. 5 ), that the recess 51 is formed, for example, conical or truncated cone-like and the corresponding cam 24 of the linear drive means 20, 25 has a corresponding shape such that it fits positively after extension in the recess 51 and through the corresponding Kustrstumpfwandungen 53 not only one Forming produces, but also a positioning takes place.

The mode of operation of the device according to the invention or the method according to the invention will be explained below.

Before the kiln inlet 5, the carriers 30 are inserted with their feet 31 in the rails 40. At a free end of the support column 37 is - if not already equipped with it - a support member 43 for a component 2 is mounted. Subsequently, the component 2 is placed positionally accurate. If the component 2 is an already preformed component 2, the support element 43 can be designed such that it acts on specific contours of the component 2 or engages with corresponding pins, for example through holes already inserted.

Subsequently, the linear drive 25 moves with the cam 24 under the opening 51 of the foot 31 of the carrier 30. The cam 24 is hydraulically, pneumatically or electromagnetically retracted into the recess or the engagement means 51. Subsequently, the linear drive 25 moves the carrier 30 with the component 2 through a possibly existing first furnace door 10, the O-feneinlaufzone 5 and possibly a second gate, which separates the inlet zone 5 from the heating zone 6.

The driving movement ends when the linear drive 25 with the cam 24 in the region of the sprockets 16a, 16b or pulleys 16a, 16b and above an axis 17 is located. The cam 24 of the linear drive 25 is now lowered down so that the linear drive can drive out of these areas again in front of the furnace. Here, it likewise promotes the next carrier 30. By providing grooves, carriers longer than the longitudinal distance between adjacent cams 18 can also be used.

The carrier 30 which is located in the region of the wheels 15a, 15b, is now continued by the fact that cams 18 on the outer circumference of the transport device 4 and the respective upper strand 13 of the chain or belt, the circulation of the wheels 15, 16 obeying, the wheel 15 go up and run into the grooves 50 from behind. At the moment where the cams 18 abut the groove walls or groove bottoms 52, the carrier is transported by the chain through the heating zone 6. By providing the grooves which are longer than the longitudinal distance between adjacent cams 18, it is also possible to use support elements 30 which are longer than the cam longitudinal spacing.

Preferably, the movements of the linear drives and the chain and belt drives are synchronized. This means that the first linear drive conveys at high speed, gently decelerates in the area of transfer and then conveys so that the cams of the chain or belt drive engage smoothly and convey further. The linear drive thus moves a small way with the chain speed until the intervention is solved. At the transfer point, according to the procedure, the linear drive leads with the chain, engages in the carrier and then increases the conveying speed while the cams of the chain drive submerge.

At the end of the heating zone 6, the linear drive 20 is already waiting for the carrier 30, wherein the cam 24 of the linear drive 20 enters the opening 51 at the moment when the carrier 30 is located above it. This preferably also takes place in the deflection point of the respective chain 12 or of the belt 12, so that the cams retract from the grooves 50 while the cams 24 enter the carrier 30 into the opening 51. The linear drive 20 can now draw the carrier 30 from the heating area or the heating zone 6 through the gate 9, through the outlet zone 7 and through the second gate 11 positionally accurate to the outside.

The conveying speeds of the linear drives 20, 25 can in this case be considerably higher than the conveying speed of the transport device 4. In particular, for example, transport speeds of 10 m / sec. possible.

Preferably, the lock doors 8, 9 and the gates 10, 11 are controlled such that the movement of the linear drive causes a gate opening at the appropriate times and close the doors immediately after the passage of the carrier. As a result, a cost-effective energy-saving operation of the furnace is possible.

Notwithstanding the preferred embodiment described above, the promotion by the transport device 4 can already begin in the kiln inlet region 5 and end in the kiln outlet region 7, then either gates are present between the kiln inlet region 5 and the heating zone 6 and the kiln outlet zone 7, which correspond to the passage of the parts to open and close are controlled or no gates are present, but possibly only locks that are made by appropriate hot or cold air curtains or Luftabsaugungen.

After the carrier 30 has been completely pulled out with the component 2 from the oven, the part is removed and further processed. The carrier is also removed from the rails and returned to the oven inlet via suitable return means and inserted there again in the rail.

In the device according to the invention and the method according to the invention, it is advantageous that the support element or the part carrier 30 is guided for the most part outside the furnace. As a result, only smaller parts of the parts carrier are warmed up, thus minimizing energy loss by cooling the parts carrier outside of the oven.

The fact that the entire transport device is located outside of the furnace, it is possible in the case of damage, maintenance or the like to get to the transport device and repair damage or perform maintenance without the oven must be turned off. This also increases efficiency and reduces energy consumption.

The respective engagement means of the transport devices 4, 20, 21 or the carrier 30 need not be cams or tines, any type of mutually corresponding shapes that can lead to a propulsion, are suitable. In addition, the engagement means need not be located in the bottom of the carrier. The cams or other means of the transport means 4, 20, 25 can equally attack on the front or rear transverse edges of the carrier.

In the invention it is also advantageous that, in the event that parts fall off the pick-up and rest on the furnace bottom, a special carrier with a driving over the ground dozer blade can be inserted into the guide rails and this component out of the furnace.

Claims (9)

1. A method for heating steel parts in which the steel parts to be heated are conveyed through a furnace (3) and are heated to a predetermined temperature in the furnace (3) and in which a transport apparatus (4) is provided for transporting the parts through the furnace (3), characterized in that a first transport device (12) takes up the parts in a precisely positioned way and transports them through the furnace (3) to heat them and after the heating, a second transport device (20) takes the parts from the first transport device at a predetermined transfer point or transfer area and then conveys them out of the furnace (3) at an elevated speed and supplies them in a precisely positioned way to another transfer point for further processing.
2. The method as recited in claim 1, characterized in that a third transport device (25) is provided, which takes up the parts (2) in a precisely positioned way before the heating and before the furnace (3) and conveys the parts (2) into the furnace (3) at a high speed and in a correctly oriented and correctly positioned way and, at a predetermined transfer point or transfer area, gives the parts (2) to the first transport device (12) in a precisely positioned and precisely oriented way, which continues to convey the parts through the furnace (3) at a lower speed.
3. The method as recited in claim 1 and/or 2, characterized in that the parts (2) to be heated are placed onto supports (30) and the supports (30) have first engaging means (50, 51) that are engaged by second engaging means of the transport device in such a way that a precise position and orientation of the support (30) is assured at all times during transport.
4. The method as recited in one of the preceding claims, characterized in that the parts (2) are heated with radiation and/or convection and/or induction and/or microwaves.
5. An apparatus for heating steel parts, having a furnace (3) for heating the steel parts and having at least one transport apparatus (4) for conveying the parts through the furnace (3), in particular an apparatus for carrying out a method as recited in one of the preceding claims, characterized in that the at least one transport apparatus (4) has at least one first transport device (12), which is situated in or at a heating area (6) of the furnace (3) and is embodied to transport the parts during the heating, and the first transport device is followed by a second transport device that extends beyond the length of the furnace (3) in the transport direction so that the second transport device (20) is able to convey parts out of the furnace (3); the transport apparatus (4) is situated outside the furnace (3) and has engaging means (18, 24) for engaging with corresponding engaging means (50, 51) on at least one support element (30), which is transported outside of the furnace (3) by the transport apparatus (4) and is held in its position and orientation; and the support element (30) extends through a furnace wall in subregions and on the inside of the furnace, has a device (43) for supporting the parts (3).
6. The apparatus as recited in claim 5, characterized in that a third transport device (25) is provided, which extends from an area situated before the furnace (3) in the transport direction to the first transport device (12) in such a way that the latter is able to convey the parts (2) into the furnace (3).
7. The apparatus as recited in one of claims 5 or 6, characterized in that the at least one support element (30) for the parts (2) that are to be heated in the furnace (3) has a first region (31) that is guided in a guiding device (40) from the furnace inlet to the furnace outlet, vertically and in a horizontal transverse direction relative to the conveying direction and the support device (30) is also provided with engaging means (51) for corresponding engaging means (24) of the second and third transport devices (20, 25) and in addition, engaging means (50) are provided for corresponding engaging means (18) of the first transport device (12).
8. The apparatus as recited in one of claims 5 through 7, characterized in that in a furnace wall through which a subregion of the support (30) extends, a longitudinal slot in the transport direction is provided, through which a subregion (37) of the support (30) extends.
9. The apparatus as recited in one of claims 5 through 8, characterized in that a slot (42) in the furnace wall is provided and is sealed toward the outside by means of suitable sealing devices so that no air from outside penetrates into the furnace (3) and thermal losses to the outside due to radiation and/or convection are prevented; the sealing device is composed of plastic sealing lips extending longitudinally along the slot and extending into the slot from the slot edges and/or longitudinally extending brush elements that have metal and/or ceramic and/or glass and/or plastic fibers that are densely arranged and extend into the slot and/or metal plates are provided, which extend parallel to the surface of a furnace wall in which the slot (42) is provided, can be pivoted across the slot (42) in a spring-loaded fashion and perpendicularly to the slot (42) so that a support extending through the slot (42) pivots the sealing device out of the region of the slot and after the passage of the support, the sealing devices spring back or move back into the slot (42).

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