DE1758011B1 - Continuous furnace for carburizing or carbonitriding - Google Patents

Description

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The invention relates to a continuous furnace for achieving the desired depth of carburization Carburizing or carbonitriding of workpieces from required conditions through experiments to ermit steel, but it can also be applied to ovens, teln and here significant deviations from the gedie to accept values and rejects for carrying out other heat treatment values, process, as far as it is here as in the case of the S These disadvantages are in the furnace according to carbonization or carbonitriding is required that the invention avoided.

Workpieces in the oven together in various ways. The invention relates to a continuous oven

exposed atmospheres. for carburizing or carbonitriding, the marked

The carburizing in gas atmosphere takes place in three draws is through one provided with an inlet door successive procedural stages take place. Zu- io heating chamber, one of the heating chamber Next, the workpiece is placed in an atmosphere that can be separated by an intermediate door and prevents decarburization until the chamber is connected downstream of the transport device Has the required temperature for carburizing to transport into the heating. Subsequently, the workpiece is brought into a chamber and becomes a work piece rich in excess carbon The atmosphere is heated, the feed point in the heating chamber, transport device is that from her carbon in the lines for the transport of workpieces from the Workpiece diffused into it. By choosing a suitable transfer point through the open intermediate door in The residence time of the workpiece in this atmosphere can determine the penetration depth of the carbon in port devices for the transport of workpieces the workpiece can be influenced. Finally, in ao, from the initial part of the carburizing chamber becomes one a third process stage the workpiece of an outlet door and a locking device that Exposed to an atmosphere that is so composed, the intermediate door is only allowed to open when that an equilibrium between at least the entrance door is closed in it. retained carbon and that on the surface of the furnace according to the invention is the

The desired carbon content of the workpiece is made. 25 Intermediate door between the heating chamber and the In this diffusion stage, the carburization chamber is closed by diffusion, when the carburization chamber is closed brought into the surface of the workpiece of workpieces in the heating chamber penetrated carbon, an edge layer in which the inlet door is to be opened. As a result of the geder Carbon content in the desired degree closed intermediate door can the atmosphere from the inside of the workpiece to the workpiece surface at the heating chamber not into the carburizing chamber increases. step over. If on the other hand to spend

There are continuous furnaces for carburizing known, workpieces from the heating chamber in the processing to which these three process stages in the essential carbonization chamber the intermediate door is opened Borrowed in a single chamber, the inlet door is closed. As a result, a the. This is usually a puff in the oven that causes a significant overflow elongated chamber, one end of which with the work of furnace atmosphere from a furnace chamber into the pieces are charged and the other end of which would cause others, do not arise, the workpieces removed after the run. The invention enables the implementation of a

will. Because normally the chamber is based on its continuous carburizing process that is in it Length is filled with workpieces, must be 40 that initially the workpieces under not bringing in new workpieces and removing the carburizing atmosphere in a heating chamber carburized workpieces heated the doors on both at the same time, then placed in a carburizing chamber Ends of the chamber are opened so that the and there continues to be under a carburizing atmosphere heated in the chamber by a chamber, finally cut into a diffusion chamber migrates into the other or is carried away and discharged from it, whereby a mixes. Therefore, in the known furnaces it is difficult to exchange the furnace atmosphere between the furnace, the one for the implementation of the three heating chambers and the carburizing chamber Driving stages serving zones, the heating zone, which is prevented that during the time in which Carburization zone and the diffusion zone, against other workpieces introduced into the heating chamber to delimit each other. Since the degree of carburization will be 50, the connection between heating and Aufvon the dwell time of the workpiece in the carburization chamber is closed. When the carburizing Atmosphere depends and since this carbonization chamber and the diffusion chamber hold time are in turn linked by the throughput speed, it is then also necessary Workpieces depends on the chamber, becomes Hch, the heating chamber and the carburizing through complete the migration of the carburizing atmosphere against each other when Werkaus the designated zone of the carburization pieces are removed from the diffusion chamber, degree influenced. It is difficult then, if not this can be done simultaneously with the introduction of even impossible to be done in the heating chamber for workpieces with different workpieces, however Cross-sections to the desired carburization depth, it is also possible to insert workpieces received, and it may even be that the pre-carburization depth 60 in the heating chamber at other times at various points in the work as the discharge of workpieces Piece surface is different. the diffusion chamber.

It is known, the composition or embodiments of ovens according to the earth The carbon content of the atmosphere in the compounds is shown in the following on the basis of the drawing to regulate different sections of a furnace, each of which is described

but this regulation is made by wandering the atmosphere. 1 a floor plan of a complete

Sphere from one furnace section to the other as set-hardening plant showing a carburizing furnace made considerably more difficult that it also contains necessary according to the invention.

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F i g. 2 shows a vertical longitudinal section through FIG. 2 and 3 can be seen, is part of the

the heating chamber of the in F i g. 1 furnace shown, radiant tube burner 29 above and another part

while arranged below the workpieces 33.

F i g. 3 shows a vertical cross section through the workpieces or their support devices can heating chamber of the stove shows. 5 can be arranged in one or two rows;

F i g. 4 shows a vertical longitudinal section and FIG. 1 shows the arrangement in two rows, and for

F i g. 5 shows a vertical cross-section through which a pair of rails 31 is provided in each of these rows.

Carburization chamber of the furnace. see. The introduction of the workpieces into the heating

F i g. 6 shows a modification that takes place in the antechamber, as in FIG. 1 recognizable by a Embodiment shown in the standing figures io with 34 designated door. A kiln car or factory Diffusion chamber with a turntable, while piece container, which is initially the one shown in FIG. 1 with 35 loading

F i g. 7 assumes the control position shown in a schematic representation, is through a door 36

approximately devices for the doors and transport brought into an antechamber 37, so that he is now the

shows the devices of the furnace. Position 38. From position 38 he becomes

In Fig. 1, the furnace 15 for carburizing is designated by a pusher 39 through the inlet as a whole with the reference numeral 10. The door 34 in the interior of the heating chamber in the case hardening device also contains a position 40 or 40 α pushed. Quenching tank 11, which, as described in British patent 987 338 is located in the end wall 27 of the heating chamber, may be formed. Another pusher device, the two Furthermore, the insert hardening device has a 20 slide 41, the mechanical washing device 12 and a tempering furnace 13, which can be connected and can be electrically heated parallel to each other. They are arranged in the quenching tank so that one of the slides 41 for processing workpieces are moved by means of a work conveyor 14 located in position 40 from the quenching tank to the washing device piece container and the other slider 41 to the container 12 and by means of a conveyor 15 from there to push a tempering furnace located in position 40 α , from which they are brought out through a workpiece container in the longitudinal direction of the heating conveyor 16. At the conveyor chamber on the pairs of rails 31 is used. 16 is followed by a conveyor 17 from which the workpieces to be hardened are If a workpiece holder one of the workpieces dealt with 42 and is removed and the workpieces to be hardened are placed on the transfer points marked 43 in the heating. 30 chamber, it is reached by a transport device carrier designed as a push-to-take workpiece device 44, which in turn is attached to the conveyor devices transversely to the adapted troughs or pallets arranged in the heating chamber. Rows through a door 45 into the on-The workpiece carriers are designed so that the carbon chamber 20 is displaced. In the on-access of the furnace atmosphere to the carbonization chamber 20 to be hardened, the workpiece containers are not obstructed in the surfaces of the workpieces. arranged in a row, but notwithstanding the conveyor 17, a further embodiment also includes the arrangement in multiple conveyors 18, which allows the workpieces to be treated ren rows. The workpiece containers are brought to the furnace. through the pusher 44 in the loaded with 59 β

The furnace contains a position indicated in its entirety by 19 40 in the carburizing chamber Heating zone, one with a total of 20 and can then be used in the longitudinal direction of the recorded Carburizing zone and one with 21 carburizing chamber are conveyed further, drawn diffusion zone. The carburizing zone 20 has the carburizing chamber, similar to the and the diffusion zone 21 are in a common heating chamber, a support structure, which consists of vertical Chamber arranged. 45 side parts 45 and horizontal top and bottom

The heating zone shown in Figs. 1, 2 and 3 share 46 and 47 consists. The side walls of the 19 has a supporting structure that consists of vertical chambers with 48, the ceiling or the vault Side parts 22 and a horizontal upper part 23 with 49, the bottom with 50 and the end walls with 51 consists. A chamber 52 and 52 is designated within the supporting structure. All of these walls exist arranged, whose designated 24 side walls, 50 made of refractory material. A pair of rails 53 that like the bottom designated by 25 and that by 26 in FIG. 5 can be seen, is used to transport a designated ceiling, made of refractory material stand. The end walls 27 and 28 of the chamber are the length of the carburizing chamber. also made of refractory material. From on the end wall 52 of the carburizing chamber is one of the side walls 24 to the opposite 55 arranged a further pusher 55 which Running sidewall 24 is a number of jet serves to hold the workpiece through the length tube burners 29 arranged, some of which move in the carburizing chamber. Drawings are denoted by the reference numeral 29 In the carburizing chamber are above the and their flue gases in a radiant tube burner designated as a total of 30 workpieces with 56 drawn flue gas can be derived. The Auf- 60 arranged, the flue gases through a 57 The heating chamber contains two pairs of rails 31, which are discharged on the designated flue gas duct, which is used to accommodate the workpieces within the length of the carburizing chamber Troughs, hollows or kiln cars can be slid or moved from the ceiling or the vault 49 to are movable. above the height of the workpieces or workpiece length F i g. 3, two troughs or kiln cars with apron 58 extending downwards are attached, the reference numeral 32 denotes, while those on the chamber in a serving for carburizing them arranged workpieces which are divided with 33 loading part 20 and a diffusion part 21, drawn Take a stand. As well as from these parts for the sake of simplicity, however, as

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Carburization chamber 20 and diffusion chamber 21 in each case required times to control signals are designated. releases the actuators.

After passing through the carburizing As far as the drive devices are pneumatic

and diffusion chamber are formed in the position 59- working cylinder, can get the Workpiece containers can contain solenoid valves by means of a 5 actuating device, the Pushing device 60 through a door 61 on through from the control device 80 A lowerable platform can be pushed, the control signals can be opened and closed, while is located in the area of the quenching tank 11. rend when the drive devices are electric

The heating motors are used on the ceiling or on the vault. They are actuated by the chamber is a circulation fan 62 is arranged, and 10 control device controlled contactors take place on the ceiling of the carburizing chamber.

two such fans 63. The furnace chambers are

with a number of closable openings wrote:

Mistake; there is one marked 64. It is assumed that the exit door 61 is

Flap at the antechamber 37, a flap 65 at _{15 has} just been closed, after a workpiece container from which further flaps 66 are in the end wall 28 of the position 59 on the above the quenching tank 11 through the pusher 60 of the heating chamber opposite the inlet door 34. Arranged heating chamber, and the carburizing-ordered platform has been conveyed, the chamber then has a flap 67 opposite which is lowered. All other doors of the furnace are connecting door 45 and a flap 68 in the front _ao closed at this time, and positions 38, 40, wall 51. 40 a, 42, 43, 59 α and 59 are not at this time

In the case of the in FIG. 6 illustrated embodiment occupied with workpiece containers, is at the end of the carburizing chamber 71 a Now the passage of workpiece containers

Diffusion chamber 70 arranged so that it started laterally through the oven with the door 36 from the carburizing chamber 71. The diffusion 25 is opened and ankammer70 on the conveyor 18 by means of a is not always a workpiece chamber with the carburizing ordered ratchet slide 71 connected, rather is between these containers from position 35 to position 38 in the Chambers a connecting door 73 arranged. Inside the antechamber 37 is brought. The door

In the diffusion chamber 70 there are jet 36 is now closed and then the tubular burner 74, and opened as a transport _device for the 3o inlet door 34. The workpiece container is now through the connecting door 73 entering work at right angles to its previous moving pieces or workpiece container to the exit door 75 direction that it had on the conveyor 18, a turntable 76 is used, which is continuously or intermittently driven by means of the pusher 39 through the open center can be. Admission door 34 through in one of the two positions

In the case of the FIG. 6 described embodiment ₃₅ 40 or 40 α inside the heating chamber 19 contains the carburizing chamber pushed three pairs of rails. In which of the two positions 40 or 71 a, 71 b and 71 c, in which workpieces or 40 α the workpiece container arrives, depends on the workpiece container being moved by a pusher which of the two rows of workpiece containers, which is similar to that in the Heating chamber 19 is next advanced the one shown in FIG. 1 with 55 designated device, where ₄₀ is. The advance of the two rows from Werkbei, however, deviating therefrom, three slides for the piece containers in the heating chamber 19 takes place where three pairs of rails are provided. changing. However, if in the carburizing chamber

At the end of the carburizing chamber 71 is a 20 two side-by-side rows of Pushing device 77 arranged, the pushing direction of which workpiece containers are arranged, are both 45 rows arranged in the heating chamber 19 run transversely to the longitudinal direction of the pairs of rails and which is designed similarly to that of the workpiece containers advanced at the same time, First embodiment described shock device Now the two slides 41 are common

device 60. is pressed and one of them catches the one on the

The exiting from the exit door 75 work position 40 or 40 α located workpiece container pieces or workpiece container are on a 50 and moves it in the longitudinal direction of the heating conveyor 78, which is designed as a roller conveyor chamber, so that the first in the same row can transported away. sensitive workpiece container position 43 or 42

To operate the entry, exit and occupies.

Intermediate doors and the bumpers in the Then the intermediate door 45 is opened and the

required sequence, each of these parts ₅₅ pushing device 44 is actuated, so that the workpiece container drive is equipped with its own pneumatic or electrical position 42 or 43. The doors are expediently reached through the opening of the door 45 into the position 59 α, which is moderately due to the pneumatic working cylinder. The direction of movement of actuated while the pushing devices serving as transport devices in position 42 or 43 in position 59 α are operated by electric motors 60 as shown in FIG. 1 clearly visible to be driven at right angles. Such an arrangement is that direction of movement in which the work schematically in FIG. 7 shown, in which the doors piece container, the heating chamber 19 and the raising and pushing devices with their reference numerals and carbon and diffusion chamber 20, 21 of the furnace pass through the associated actuating devices with the.

Reference numerals and the addition α are designated. 65 Now the connecting door 45 is closed and the actuating devices are operated with a control device 55 in such a way that all device 80 is connected, which is essentially designed as a loan in the carburizing chamber 20 and the electrical timer and workpiece containers located in the diffusion chamber 21

be moved towards the end of the chamber, whereby the workpiece container closest to the end of the chamber comes into position 59. After the push-in device 55 has been withdrawn, there is a free space at the point indicated by 59 α. The outlet door 61 is now opened and the pushing device 60 actuated so that the workpiece container located in the position 59 is conveyed onto the platform located above the quenching tank 11. The outlet door 61 is then closed, and thereafter the process described is ended.

The connecting door 45 is only opened when both the inlet door 34 and the outlet door 61 are closed.

In the further, in F i g. 6 illustrated embodiment the second intermediate door 73 and the outlet door 75 are similar to the previous one Exemplary embodiment with a control device corresponding to the control device 80 connected in such a way that the second intermediate door 73 ao are opened at the same time as the intermediate door 45 can as long as the outlet door 75 is closed.

If, deviating from this, the operation is carried out so that the outlet door 75 at the same time as that between the connecting door 45 arranged in the heating chamber and the carburizing chamber ag can be open, the control device must cause the connecting door 73 to be closed at the same time. In all of the configurations described above, there is no significant transfer of furnace atmosphere from one to the next 'part of the furnace. It is therefore guaranteed that in the heating zone or heating chamber 19 get an atmosphere without carburizing properties remains, while the composition and properties of the atmosphere of the carburizing zone 20 also remain unchanged. The carburization of every workpiece that has passed through the furnace takes place that is, during a period precisely determined by the control device 80, during which the Workpiece container pass through the carburizing zone 20, in a carburizing atmosphere whose Properties are constant and predetermined. This creates a layer depth and distribution of the carbon content throughout the layer depth, carburization remains the same for all treated workpieces achieved.

The mutually offset arrangement of the sections, seen in the workpiece passage direction 19, 20 and possibly also 21 of the furnace and which took place at right angles to the workpiece passage direction Arrangement of the pushing devices serving as a transport device allow closing the intermediate doors, without it being necessary, between the workpieces or workpiece containers Keep gaps in the longitudinal direction of the furnace. Therefore, the movement of the workpieces or Workpiece container in the longitudinal direction of the furnace in turn made by simple pushing devices, and due to the elimination of gaps between the consecutive ones in the longitudinal direction of the furnace Workpieces or workpiece containers result in a considerable saving in terms of furnace length.

In the exemplary embodiments, the successive furnace parts are, as is usually appropriate, in the same horizontal plane offset from one another. The dislocation of the successive However, sections of the furnace can also be made in other ways, for example vertically or horizontally and vertically.

A further increase in the accuracy of the depth and intensity of the carburization can be achieved by automatic Control of the composition of the atmosphere, particularly in the carburizing zone 20, but also the heating zone 19 and the diffusion zone 21 take place.

Any interruptions in furnace operation only affect those in the carburizing zone 20 existing workpieces, and even with these workpieces, there is usually their dwell time is known in the carburizing zone before the business interruption, through suitable further treatment the prescribed carburization can be achieved after the furnace has started operating again.

While in the embodiments described above with reference to the drawing Movement of the workpieces and workpiece containers was carried out by shock devices, the Invention can also be carried out by means of other conveying devices. For example, can also one or more belt or plate conveyors can be used, or one or more sections of the furnace can be designed as rotating chambers that rotate about their longitudinal axis and are equipped inside with a helical guide arrangement, of the screw threads the workpiece containers are conveyed through the chamber in the axial direction.

Claims (9)

Patent claims: 1. Continuous furnace for carburizing or carbonitriding, marked with a an inlet door (34) provided heating chamber (19), one of the heating chamber (19) through an intermediate door (45) separable carburizing chamber (20) is connected downstream, as well as through Transport devices (41) for transporting workpieces introduced into the heating chamber (19) to a transfer point (42, 43) in the heating chamber (19), transport devices (44) for transporting workpieces from the transfer point (42, 43) through the open Intermediate door (45) in the initial part of the carburizing chamber (20) and transport devices (55) for transporting workpieces from the initial part of the carburizing chamber (20) to an outlet door (61) and a locking device (80), which only allows the intermediate door (45) to be opened allowed when at least the inlet door (34) is closed. 2. Continuous furnace according to claim 1, characterized in that the outlet door (61) at the end a diffusion chamber (21) is arranged, which is in constant communication with the carburizing chamber (20) stands, with a locking device (80) opening the connecting door (45) only allowed when both inlet door (34) and outlet door (61) are closed. 3. Continuous furnace according to claim 1, characterized in that an outlet door (75) on Outlet a diffusion chamber (70) is arranged from the carburizing chamber (71) through a second connecting door (73) is separable and the connecting door (73) as a result of a locking device (80) only opens when the 009534/144 1 758 Oil ίο leave door (75) closed and if the first connecting door (45) and / or the inlet door (34) are closed, whereby for the transport of workpieces from the carburizing chamber (71) a transport device (77) is provided through the connecting door (73) into the diffusion chamber (70) is, while a transport device (76) for transporting workpieces within the diffusion chamber (70) serves as its outlet door (75). 4. Continuous furnace according to claims 1 to 3, characterized in that the heating chamber (19) and the carburizing chamber (20) so essentially parallel to one another and in the longitudinal direction are arranged one after the other that seen in the longitudinal direction of the chambers, the heating chamber (19) ends behind the beginning of the carburizing chamber (20) and the connecting door (45) is common in one of the two chambers (19, 20) is arranged extending in the chamber longitudinal direction wall. 5. Continuous furnace according to claim 4, characterized in that the transport devices (41, 44, 45), the workpiece containers for transporting the workpieces or the workpieces serve through the furnace parts (19, 20), designed as pushing devices and arranged in such a way are that the pusher (41) the workpieces through the heating furnace (19) in its Promotes the longitudinal direction, while the pusher (44) the workpieces perpendicular to the the latter direction through the connecting door (45) into the carburizing chamber (20) promotes and while the pusher device (55), again perpendicular to the latter Direction that promotes workpieces in the longitudinal direction of the carburizing chamber (20). 6. Continuous furnace according to claims 4 and 5, characterized in that in that Area in which the heating chamber (19) and the carburizing chamber (20) overlap, one or more flaps (66, 67) are arranged, which provide access to the chambers enable. 7. Continuous furnace according to claims 3 to 6, characterized in that a diffusion chamber (70) at the end of the carburizing chamber (71), but offset in the longitudinal direction with respect to this, is arranged, between the carburizing chamber (71) and the diffusion chamber (70) a further intermediate door (73) is arranged and a transport device (77) serves to transversely move workpieces from the carburizing chamber (71) to their transport direction within the carburizing chamber (71) into the diffusion chamber (70) to promote. 8. Continuous furnace according to claim 7, characterized in that within the diffusion chamber (70) designed as a turntable Conveyor (76) is arranged. 9. Continuous furnace according to claims 1 to 8, characterized in that the actuation of the Drive devices for the doors and conveyors by a control device designed as a timer (80) takes place in a predetermined order. For this purpose 2 sheets of drawings