EP0342343B1 - Roll hearth heat-treating furnace, especially one suitable for small metal and ceramic parts - Google Patents

Description

The invention relates to a roller hearth furnace according to the preamble of claim 1.

A roller hearth furnace of this type is known from DE-PS 28 40 282. In the known design, refractory bricks are provided in the refractory lining of the side walls of the roller hearth furnace, which are provided with openings for receiving the rollers. The refractory bricks are arranged in the opposite side walls in such a way that openings assigned to one another are aligned with one another. The rollers can then be inserted through the openings from the outside and removed again in the same way if a repair is necessary.

In order to prevent gas and heat loss through the openings in the refractory bricks, the diameter of which must be sufficiently larger than the diameter of the rollers, cavities are provided in the refractory bricks, into which insulating and refractory material, such as kaolin wool, is pressed that can then fit closely to the roll diameter.

A fundamental disadvantage of such roller hearth designs is that, for reasons of strength, the diameter of the rollers themselves cannot fall below a certain value, and the distance between the rollers cannot be chosen to be as small as desired. Since the rollers are always pulled outwards, the openings for mounting the rollers always weaken the supporting cross-section of the side walls, which must not exceed a certain dimension. A certain distance between the rollers must therefore be due to the between the bearing openings remaining supporting web part necessary for the roles. The necessary distance between the rollers and their diameter determines the size of the parts to be treated, if separate support plates are not to be provided, which run over the rollers and accommodate the parts to be treated. The disadvantage in this case is that the mass of the support plates must always be heated up when passing through the roller hearth furnace, which causes unnecessary heat loss.

In other types of industrial furnaces, for example in so-called tunnel furnaces (DE-PS 35 10 801), in which the parts to be treated are pushed through the furnace on transport elements, the space problem existing in roller hearth furnaces does not occur, because for the replacement of the rollers next to the No space must be made available to the oven. However, it remains disadvantageous that the transport elements provided there instead of kiln cars must also be heated up in the manner of rust when passing through the tunnel furnace. The arrangement of rotatable rollers in lateral spacers provided there does not change anything. The features provided there can also not be used for roller hearth furnaces, in which the rollers are arranged in a stationary manner, because a replacement of stationary rollers would not be possible because of the guide provided for the rust-like transport elements only inside the furnace.

The invention is therefore based on the object of designing a roller hearth furnace of the type mentioned in such a way that, with the smallest possible roller diameter, the mutual spacing of the rollers can also be chosen to be very small, without strength problems in the manufacture of the furnace walls or difficulties when changing rollers .

To solve this problem, the characterizing features of the claim are in a roller hearth furnace of the type mentioned 1 provided. This configuration has the advantage that the load-bearing capacity of the furnace side walls is independent of the storage of the rollers, because these can be accommodated in separate support beams which, together with the rollers, form module-like modules for the production of a roller bed which can be used in the furnace. The support beams for the rollers, in contrast to the materials previously used for the lining of the side walls, can be made from a material of considerably higher strength, so that, despite the closely arranged rollers, they can also have sufficient load-bearing capacity to absorb the supporting forces of the side walls.

It is possible to make the design according to subclaims 2 and 3 so that the load-bearing capacity of the side walls is not dependent on the strength of the supporting beams. In contrast to the known openings for individual rollers, the openings provided for pulling out the roller table components laterally are each much larger, so that larger and more stable webs remain between the openings.

It is particularly advantageous, according to the features of claims 4 to 9, to provide a separate installation frame into which the roller table components can be inserted like a drawer from one side and the other. The mounting frame can be designed with the roller table elements as a prefabricated unit that is installed in a furnace housing.

According to the features of claim 8, the drive for one or for all roles of a component can be integrated on the bearing beam on one side. The features of claim 9 allow cooling of the mounting frame and the drive elements held in this type in a particularly simple and effective manner.

In order to get the problem of tightness and heat insulation in the area of the roller table components under control, it is expedient to provide the features of subclaims 10 and 11. The load-bearing capacity of the rollers can also be increased by arranging an additional support beam lying more towards the center of the roller. The features of claim 12 result in a stable structure for these rolling table components.

The features of dependent claim 13 enable a relatively light design for the rolling table components. The features of claims 14 and 15 also open the possibility in the embodiment not provided with a mounting frame that only the rollers assigned to a roller table component are driven together, which is also possible, for example, by assigning a separate drive unit which, as in the case of Type with mounting frame in the area outside the furnace walls can be attached to the front of the roller table component. This configuration then also opens up the possibility of increasing the roller speed, for example in the case of the roller table components which are closer to the exit of the furnace, so that the parts are removed quickly. Of course, it is also possible to drive all the rollers together using a known chain drive. However, the configuration according to the invention also enables the individual drive just mentioned.

The invention also makes it possible to choose the spacing of the individual rollers, which may have small diameters, from one another to be very small. This brings with it certain difficulties in the generation and maintenance of a uniform furnace atmosphere, since that for the passage of the hot gases from the space below the roller bed into the space above it is severely restricted. It is therefore expedient if the features of claims 16 and 17 are provided by means of which forced circulation of the furnace atmosphere is achieved is, the roller conveyor itself exerts a certain sieving effect to even out the flow.

Fig. 1

einen schematischen Längsschnitt durch einen erfindungsgemäß ausgestatteten Rollenherdofen,

Fig. 2

den Schnitt durch den Rollenherdofen der Fig. 1 längs der Linie II-II,

Fig. 3

den Schnitt durch den Rollenherdofen der Fig. 1 und 2 längs der Linie III-III in Fig. 2,

Fig. 4

die vergrößerte Darstellung eines der aus Fig. 2 ersichtlichen Rollentischbauelemente in Draufsicht,

Fig. 5

den Teilschnitt durch das Rollentischbauelement der Fig. 4 längs der Schnittlinie V-V,

Fig. 6

die Stirnansicht des Rollentischbauelementes der Fig. 4 in Richtung des Pfeiles VI der Fig. 4,

Fig. 7

eine vergrößerte Detailschnittdarstellung durch das rechte Lagerende eines Rollentischbauelementes gemäß Fig. 4 und 5 im eingebauten Zustand,

Fig. 8 und 8a

Schnitte durch die Lagerung der Fig. 7 längs der Linien VIII und VIIIa,

Fig. 9

einen schematischen vergrößerten Längsschnitt durch den Innenraum eines erfindungsgemäß ausgestalteten Rollenherdofens ähnlich Fig. 1, jedoch mit einer zusätzlich angeordneten Luftumwälzung,

Fig. 10

einen Längsschnitt ähnlich Fig. 1 durch einen Rollenherdofen gemäß der Erfindung, jedoch in einer anderen Ausführungsform,

Fig. 11

den Schnitt durch den Rollenherdofen der Fig. 10 längs der Schnittlinie XII-XII,

Fig. 12

den Schnitt durch den Rollenherdofen der Fig. 10 und 11 längs der Schnittlinie XIII-XIII in Fig. 11,

Fig. 13

eine Draufsicht auf einen Einbaurahmen aus Metall, in den die Rollentischbauelemente schubladenartig eingeschoben sind,

Fig. 14

die Schnittdarstellung durch den Einbaurahmen der Fig. 13, jedoch in der Einbaulage in einem Ofengehäuse,

Fig. 15

die Ansicht des Einbaurahmens der Fig. 13 in Richtung des Pfeiles XVI,

Fig. 16

die vergrößerte Teildarstellung eines der Abschlußelemente eines Rollentischbauelementes, das in den Einschubrahmen der Fig. 13 eingeschoben ist und

Fig. 17

den schematischen Schnitt längs der Linie XVIII der Fig. 16 durch das Abschlußelement der Fig. 16.

The invention is shown using exemplary embodiments in the drawing and explained below. Show it:

Fig. 1

2 shows a schematic longitudinal section through a roller hearth furnace equipped according to the invention,

Fig. 2

the section through the roller hearth furnace of FIG. 1 along the line II-II,

Fig. 3

the section through the roller hearth furnace of FIGS. 1 and 2 along the line III-III in Fig. 2,

Fig. 4

3 shows the enlarged illustration of one of the roller table components shown in FIG. 2 in a top view,

Fig. 5

4 along the section line VV,

Fig. 6

4 in the direction of arrow VI of FIG. 4,

Fig. 7

4 shows an enlarged detail sectional view through the right end of a roller table component according to FIGS. 4 and 5 in the installed state,

8 and 8a

7 sections along the lines VIII and VIIIa,

Fig. 9

2 shows a schematic enlarged longitudinal section through the interior of a roller hearth furnace designed according to the invention similar to FIG. 1, but with an additionally arranged air circulation,

Fig. 10

2 shows a longitudinal section similar to FIG. 1 through a roller hearth furnace according to the invention, but in another embodiment,

Fig. 11

the section through the roller hearth furnace of FIG. 10 along the section line XII-XII,

Fig. 12

10 and 11 along the section line XIII-XIII in Fig. 11,

Fig. 13

1 shows a plan view of a metal installation frame into which the roller table components are inserted in the manner of a drawer,

Fig. 14

13 shows the sectional view through the installation frame of FIG. 13, but in the installation position in an oven housing,

Fig. 15

the view of the mounting frame of FIG. 13 in the direction of arrow XVI,

Fig. 16

the enlarged partial view of one of the end elements of a roller table component, which is inserted into the slide-in frame of FIG. 13 and

Fig. 17

the schematic section along the line XVIII of FIG. 16 through the closure element of FIG. 16th

1 to 3, a roller hearth furnace is shown, which is provided with a housing (1) made of refractory and heat-insulating materials, which consists of an upper housing part (1a) and a lower housing part (1b). 3, the lower housing part (1b) is narrower than the upper housing part (1a), so that the lower housing part (1b), seen in the transport direction (21) of the parts through the housing (1), laterally from the upper housing part ( 1a) towered outwards becomes. The advantages of this training will be discussed later.

An interior (24) heated by heating devices (23) is formed in the housing (1), in which a roller bed (3) is provided for guiding the parts not to be treated.

As can be seen in FIGS. 1 and 2, the roller bed (3) is constructed from several, in the exemplary embodiment from five roller table components (4), which are arranged one behind the other, adjacent and in a common plane. The roller table components (4) are held laterally (see Fig. 3) in recesses (6) of the housing walls (7 and 7 ') and are thereby fixed in place in the housing (1).

As shown in FIGS. 4 and 5, each of the roller table components (4) consists of a plurality of rollers (2) which are tubular in shape and are rotatably mounted with their two ends (2a) on bearing beams (5). In the embodiment shown, this can be done by pushing end journals (13) into the open ends (2a) of the rollers (2), which are rotatably held in bushings (27) within the bearing beams (5). The bearing beams (5) are in turn firmly connected to support beams (10) via fastening anchors (15) which are further assigned to each of the bearing beams (5) towards the center of the roller. These support beams also serve as a heat shield with respect to the treatment room (24) in the furnace and as a wear-resistant leading edge for the material to be treated. Since they have to be made of highly refractory material, it is expedient if their length does not correspond to the length of the bearing beam (5), but if two supporting beams (10) are assigned to one bearing beam (5). A shorter overall length is easier to achieve with highly refractory materials, such as SiC. Such a material can be used also form very narrow webs, such as the webs (10a), between the openings for the rollers (2).

Each of the support beams (10) and each of the support beams (5) has as many openings as rollers (2) are assigned to a roller table assembly (4). Insulating adapters (12) are used between the support beams (10) and the bearing beams (5), which have the task of providing good thermal insulation from the interior (24) to the outside. These insulating fittings (12) are made from two half-shells (12a and 12b) because narrow webs, such as webs (10a), cannot be produced from the material used for the thermal insulation for reasons of strength.

In the embodiment of FIGS. 4 and 5, a common drive unit (25) is assigned to one of the two bearing beams (5), via which each of the bearing journals (13 ') is driven, namely by the fact that corresponding gear wheels (28) each for the rotary movement of each individual bearing pin (13 ') are provided. All gear wheels (28) are in rotary connection with one another, in such a way that all bearing journals (13 ') receive the same direction of rotation. The gear wheels (28) are driven by a common drive pin (26) which can be driven by a drive motor (29) which is assigned to the roller table component (4). As shown in FIG. 2, five drive motors (29) are therefore provided in the roller hearth furnace of FIGS. 1 to 3, in which five roller table components (4) are provided, all of which are located outside the housing (1) and are separated from the heated interior ( 24) are separated by the supporting beams (10) serving as heat shields and by the insulating fittings (12) and the bearing beams (5).

1 to 3, an opening (9) is provided in the housing walls (7 and 7 ') for each of the roller table components, through which each of the roller table components (4) is pulled outwards transversely to the transport direction (21), waited and can be replaced if necessary. For this purpose, the openings (9) in their width and height are adapted to the dimensions of the bearing beams (5) and sealing covers (30) are provided, which also serve the drive motors (29), the drive units (25) and the Keep the bearing beam (5) in its correct position. Wide wall parts (31) therefore remain between the openings (9), which can ensure the necessary stability of the furnace structure towards the inside. It is also possible to provide an outer support frame (39) with which the upper housing part (1a) can be supported on the lower housing part (1b). Tie rods (32), which run downwards from the upper part of the housing, can be used to lift the insulation off the bearing beams (5) and support beams (10) if the corresponding roller table components (4) are to be removed from the side.

The design according to the invention creates a roller hearth furnace with a continuous roller bed, in which, however, the storage and arrangement of the rollers is independent of the design of the side walls of the housing (1). The rollers (2) are stored in separate components and it can be seen from FIG. 6 that it is possible in this way to arrange the rollers (2) at a short distance from one another and to mount them in a rotatable manner. This is possible because the outer support and insulation construction of the housing (1) need not be taken into account in the selected embodiment.

Due to the arrangement of the support beams (10) at a distance from the bearing beams (5) and by the measure that the support beams (10) are flush with the inner wall boundary of the treatment room (24), the possibility of deflection for the rollers (2) can also be so low be held as possible. Small roll diameters can therefore also be realized. Together with the small distance between the rollers, this means that the new roller bed (3) is also very suitable for conveying small parts to be treated. Here the distance between the rollers is always chosen much smaller than the roller diameter.

How the storage of the rollers (2) can be made in detail, results from Figs. 7 and 8. It can be seen that the bearing pins (13) engage in the end faces of the hollow rollers (2) and in a rotationally fixed connection with the Rollers (2) are. It can be seen that the support beams (10), which serve as a heat shield, and the insulating fittings (12) together with part of the ceramic armature (15) in the region of the insulation (33) of the lower housing part (1b) - and the one not shown Upper housing part 1a) run, however, that the bearing beams (5) run in the area of the outer supporting structure (39) of the side wall (7), which is free at the bottom. The area in which the bearing beams (5) are arranged can therefore remain significantly cooler or can be kept cooler than the rest of the storage area for the rollers (2).

Since in the invention the distance between the rollers (2) is only very small and, as stated, is significantly smaller than the roller diameter, difficulties can arise within the treatment room (24) with regard to the formation of a uniform furnace atmosphere. The subspace of the interior (24) located under the roller bed (3) is separated from the subspace located above it by the roller bed and the possibilities for exchanging the atmosphere within the treatment room (24) are limited by the narrow distances between the rollers (2).

According to FIG. 9, a gas supply nozzle (17) is therefore inserted in the space (24b) below the roller bed (3), which is connected upstream and downstream of transverse bulkheads (19 and 20) in the transport direction (21) and in the space (24b) , through which a space (37) is created below the roller bed, in which, when gas is supplied through the nozzle (17), an underpressure and an overpressure subspace is created, which ensures that a circulation in the sense of Arrows (38) arise in the partial area of the room (37). In the configuration according to the invention, this measure serves to homogenize the furnace atmosphere, so that the small parts (18) are exposed to uniform conditions as possible when they pass through the treatment room (24). In this embodiment, the roller bed (3) acts as a type of sieve through which the gas conveyed upwards from the space (37) reaches the space above the roller bed (3) evenly.

10 to 12 a somewhat modified embodiment is shown, in which seven consecutive roller table components (4) are provided, which are constructed in principle like the roller table components (4) explained with reference to FIGS. 5 to 6. The difference here, however, is that not, as shown in FIGS. 1 to 3, a furnace with quick discharge is shown, which is made up of individual roller table components with its own drive units (24) and which is particularly suitable for hardening, shaping and the like. can serve, but that in Figs. 10 to 12 a furnace with a cooling section for annealing and sintering is shown, in which all rolling table components are equipped with a continuous individual drive of the rollers (2).

The same parts as in FIGS. 1 to 3 are provided with the same reference numerals.

In contrast to the embodiment of FIGS. 1 to 3, only one drive motor (40) is provided for all rollers (2). The drive takes place here via a common chain (41) in the area of one of the side walls of the housing (1), which contacts the corresponding toothed wheels of each of the individual bearing journals (13) and sets them in rotation. Other known types of drives are also possible. This rotary movement is then passed on to the rollers (2) via the bearing pins (13) in the manner shown in FIG. 7 via frictional contact. In the embodiment according to FIGS. 10 to 12, all the rollers (2) are driven in a constant, constant manner. The embodiment 1 to 3, on the other hand, allows the transport speed to be increased and slowed down.

13 shows a mounting frame (45) made of metal profiles, which can be installed in a heat-insulated housing in a manner not shown in detail. The mounting frame (45) has on each of its two long sides two parallel longitudinal spars (46) which are connected to each other by transverse webs (47) or (48) perpendicular to them, the transverse webs (47) on one long side and the crossbars (48) are arranged on the other long side of the mounting frame (45). Both longitudinal bars (46) are connected to a frame by cross bars (49). As can be seen from Fig. 13, two adjacent crossbars (47) are arranged on each long side at a greater distance (A) from one another, while the next crossbar adjacent to one of the crossbars arranged at a distance (A) is at a smaller distance this has. Between the crossbars (47) and (48) of one long side, therefore, the distances (A) and (B) occur alternately and the arrangement is such that two crossbars (47) on one long side, the distance (A) to each other have two transverse webs (48) with the distance (b) on the other long side. In this way, slots are created in the installation frame (45), which correspond to the recesses (6) of the previous figures and into which the roller table components (4 ') can be inserted in a drawer-like manner, in such a way that adjacent roller table components (4') are each different Long sides of the mounting frame (45) are introduced from. The distance (A) is chosen for this purpose so that it is larger than the width (C) of a roller table component (4 '). The distance (B), on the other hand, is smaller than this width, so that when a roller table component (4 ') is inserted between two cross bars arranged at a distance (A), the opposite two cross bars can act as a stop.

Each of the roller table components, as can be seen in particular from FIGS. 16 and 17, is provided on the side assigned to the insertion side with a bearing bar (5 ') which is part of a gearbox (50) which is closed at the front by a cover (51) . To the side of the cover (51), the gearbox (50) has bearing points (52) and (53) for the deflection wheels (54) and (55) of a drive chain (56), each of which, similar to the embodiment according to FIG. 1 to 3, which drives a roller table component (4 ') associated bearing journal (57) of all rollers (2'). The deflection wheel (54) is rotatably mounted on a bearing pin which sits on the gear box (50). The deflection wheel (55) serves as a drive wheel for the chain (56) and is connected to the gear (59) of a drive motor (60) via a drive shaft (58). 16 and 17 and FIGS. 13 to 15, the roller table components (4 ') can be inserted from one side into the mounting frame (45) until side stop flanges (61) of the gearbox (50) on the associated Attach cross bars (47). In this position, the roller table components can be secured to the longitudinal spars (46) by screws, not shown, which are inserted through corresponding bores (62). From the other side, a closure and also securing the position are achieved in that a closure cap (63) is inserted into the space between the two transverse webs at a distance (B) and with an extension or directly with the bearing beam of the roller table component provided on this side ( 4 ′) is screwed. The cover cap has an outer flange (64) which overlaps the associated transverse webs (48) or (47) which are at a distance (B) from one another.

Each of the gear boxes (50) can be provided with cooling fins (65) in its upper and lower region. It is of course possible to let heating or cooling elements project downwards and upwards from these gear boxes (50) or from the end cover (63), which are similar to the embodiment of FIG 1 to 3, the cooling element (22) is used to cool the gearbox (50) and the drive parts mounted in it. For this purpose, it is also advantageous to design the longitudinal spars (46) and / or the transverse spars (47, 48) as hollow profiles and to flow them with cooling air which, at one or more suitable points, is introduced into one or more of the hollow profiles via a blower becomes.

Claims (17)

1. Roller hearth-type furnace for heat treatment, especially of small parts made of metal and ceramics, comprising a heat-insulated housing (1) and rotating rollers (2) held fixed in the housing, said rollers forming a roller bed (3) for conveyance of the parts to be treated, wherein, the roller bed (3) is made up of roll-out table component parts (4) in each case consisting of several rollers (2) and bearing carriers receiving the two ends (2a) of these rollers (2), and clearances are provided in the housing (1) for the uptake of the bearing carriers and the roll-out table component parts (4) can be held mounted and detachable in the clearances (6).
2. Roller hearth-type furnace according to claim 1, wherein the clearances (6) are formed as groove-like slots in the heat insulation of the housing side wall (7), which are provided with openings (9) which go through to the exterior and in their dimensions are adjusted to the dimensions of the bearing carriers (5).
3. Roller hearth-type furnace according to claim 2, wherein the openings (9) are disposed in the opposing side walls (7,7') displaced in relation to each other by their own width as measured in the direction of conveyance.
4. Roller hearth-type furnace according to claim 1, wherein the clearances (6) are part of a mounting frame (45) which can be inserted into the housing (1).
5. Roller hearth-type furnace according to claim 4, wherein the mounting frame (45) is provided with two spans (46) running parallel to each other on each of its long sides, said spans being connected by crosspieces (47, 48) provided at intervals, the spans bordering the sides of plug-in openings for the roll-out table component parts (4') towards the top and the bottom and bordering the sides of at least a part of the crosspieces of these plug-in openings
6. Roller hearth-type furnace according to claim 5, wherein the in each case two adjacent crosspieces (47 or 48), which border on the plug-in openings, are arranged widely separated from each other, in accordance with the width (C) of the roll-out table component parts (4'), and the pair of crosspieces on the opposite sides of the mounting frame each have two stops serving as crosspieces associated with them which are separated from each other by less distance (B) in accordance with the width of the roll-out table component parts.
7. Roller hearth-type furnace according to claim 6, wherein the roll-out table component part (4') is attached to the side of a connection element passing between the stop-crosspieces, said connection element being provided with a protection cap (63) overlapping the stop-crosspieces from outside.
8. Roller hearth-type furnace according to claims 5 to 7, wherein the stringers (5') of the roll-out table component parts (4') on the side of the plug-in openings are part of a gearbox (50) with cover (51) fitting in the plug-in openings, a drive (55, 56, 60) for at least one of the rollers (2') being disposed on and in said gearbox.
9. Roller hearth-type furnace according to claims 4 to 8, wherein the spans (46) and/or the crosspieces (47, 48) are developed as hollow sections through which a coolant, cold air in particular, flows.
10. Roller hearth-type furnace according to claims 1 to 3, wherein each bearing carrier (5) is attached to at least one insulation adjusting piece (12) displaced towards the middle of the rollers.
11. Roller hearth-type furnace according to claim 10, wherein the insulation adjusting pieces (12) are in each case disposed between the associated bearing carrier (11) and a supporting bar (10), having openings (11) for the rollers (2), the diameter of which is somewhat larger than the diameter of the rollers.
12. Roller hearth-type furnace according to claim 11, wherein the bearing carrier (5) and the supporting bar (10) of each side of a roller are in each case connected with each other by means of mounting stays (15).
13. Roller hearth-type furnace according to claim 13, wherein the rollers (2) are developed hollow and in each case journal pins (13) are introduced into the front face of the rollers and are held on the bearing carrier (5).
14. Roller hearth-type furnace according to claim 13, wherein at least one of the journal pins (13, 13') is driven.
15. Roller hearth-type furnace according to claim 14, wherein the driven journal pin (13) is in drive connection with all other journal pins (13) of a bearing carrier (5).
16. Roller hearth-type furnace according to claims 1 to 15, wherein gas rotating devices (17, 19, 20) are disposed below and above the roller bed (3).
17. Roller hearth-type furnace according to claim 16, wherein a jet tube (17) is provided as a gas rotating device and diaphragms (19, 20) are disposed on the side of the roller bed (3) on which the jet tube (17) lies, in front of and behind the jet tube (17), in the direction of conveyance (21).

Images