JPH0465889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat treatment method for heat treating a metal workpiece, and a heat treatment apparatus for carrying out this heat treatment method.

[Prior Art] As is well known, when heat treating metal workpieces, a method is adopted in which the workpieces are collected in lots in order to treat them under the same process parameters. The charges, which require the same process parameters, in particular the same residence time in the furnace atmosphere, are then fed one after the other to the furnace chamber in almost continuous operation. The charge is moved as a conveying stream, that is to say one after the other, continuously or intermittently, through the furnace chamber from the charging inlet to the discharge outlet. Distance traveled by the charge in the furnace chamber,
The residence time of the charge in the furnace atmosphere is determined by its movement speed or in combination with the intermittent movement speed.

In the known method of moving the entire charge in the furnace chamber as a continuous conveying stream, it is necessary that the processing time in the furnace chamber is the same for all the charges;
Therefore, only those charges which require practically identical process conditions can be processed at the same time.

In known furnace installations, a mixed operation is not possible in the sense of simultaneously processing the charges, each of which requires a mutually different residence time in the furnace chamber.

In known furnace installations, when it is desired to process charges that require different residence times in the furnace chamber, the last charge that has been processed for a given process time is first removed from the furnace chamber. I have to wait until then. Only then is it possible to start processing a new charge whose residence time in the furnace is shorter or longer than the previously processed charge.

[Problems to be solved by the invention] The present invention eliminates the need to completely empty the furnace chamber beforehand when transferring from one type of charge to another; It is an object of the present invention to provide a method for heat treatment of metal workpieces, which allows simultaneous and continuous treatment of charges.

A further object of the invention is to provide a heat treatment apparatus suitable for carrying out such a method.

[Means for Solving the Problems] The above-mentioned object is based on the present invention and provides a heat treatment method having the features set forth in claim 1 and a heat treatment apparatus having the features set forth in claim 5. This is achieved by

After each charge has passed its own residence time in the furnace chamber, it is removed from the furnace chamber independently of the other charges. This eliminates the need to process batches of the charge with the same process parameters, and as a result, according to the invention, waste is lost when transferring from one type of charge to another. It is possible to keep the time to a minimum. Moreover, as soon as the place for the charges in the furnace chamber is emptied, practically any type of charges can be charged one after the other. As a result, even when using a small furnace, a large degree of freedom in heat treatment operations can be obtained.

Furthermore, this new method has the advantage that it takes into account the actual situation of the workpiece for each charge and can expose the charge to the furnace atmosphere in an individual manner accordingly. In contrast, known reactor equipment required residence times to be determined based on the expected worst case. This can then, for example, result in excessive heat treatment in other charges.

In order to eliminate as much as possible the mutual influence of the charges in the furnace chamber, each charge is preheated to the respective process temperature in the furnace chamber in a preheating zone before it is charged into the furnace chamber. is preferred. This ensures that the charge already present in the furnace chamber is not adversely affected by the cold charge placed next to it during the course of the process.

Although it is entirely possible to apply this new method even when the state quantities and composition of the furnace atmosphere change gradually or stepwise, For example, the calculation of the residence time is simplified when it is kept constant over the processing time.

When the change during the residence time of the charge does not exceed a certain amount, i.e. in this case when the furnace atmosphere is almost constant with respect to its state quantities and composition, the process parameters change smoothly or stepwise. This assumption also holds true when

A particularly flexible heat treatment method that is suitable for extremely different workpiece geometries requires that each charge, during its residence time in the furnace, determine the state quantities and composition of the furnace atmosphere as well as the workpieces for each charge. The required residence time is calculated from the shape. Here too, it may be particularly important to keep the chemical and physical parameters of the furnace atmosphere constantly constant within narrow limits. Furthermore, it is easily possible to take account of the particular circumstances of the individual charges.

Particularly good utilization of the transport device is possible due to the combination of a control device with a storage device in the transport device. This is because a new charge can be placed in the empty space immediately after the charge is removed. Furthermore, this method can realize fully automatic operation without human intervention.

If the conveying device has a closed track inside the furnace chamber, along which the charge can be moved, good space utilization inside the furnace chamber is obtained. This provides the possibility of moving the charge along the track in such a way that it takes only the shortest path at the time for removal or new charging. This is because the charge or the empty space can be moved from both directions to the loading or unloading port.

Depending on the location around the furnace chamber, the outlet and the charging port can be directly adjacent or can be located diametrically opposite with respect to the track and the center of the furnace chamber.

A grate is provided rotatably supported around a vertical line to form a closed track within the furnace chamber;
This grate is selectively rotatable in one direction or the other, but in at least one direction, by means of a drive controlled by a control device, with a position transmitter being coupled to the grate, and a position transmitter being connected to the grate. A particularly simple conveying device is obtained if the control device can detect the respective position of the charge on the grate or the position of the empty space using a position transmitter. For loading and unloading the charge into the grate, the conveying device is equipped with a pushing or withdrawing device, which conveys the charge onto or from the grate via an outlet or a charging port.

The control device can also be combined with a computer, which calculates for each charge present in the furnace chamber, during its residence time, the state quantities and composition of the furnace atmosphere, i.e. its physical and chemical parameters; ,
The residence time of each charge is calculated from the shape of the workpiece of each charge.

[Example] Next, an apparatus for carrying out the heat treatment method according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a furnace equipment 1 comprising a preheating zone 2 and an industrial furnace 3 connected to the outlet of the preheating zone 2 for heat treating metal workpieces. The material is, for example, carburized in a predetermined atmosphere. Control of the driving parts and various devices of the preheating zone 2 and the furnace 3 is performed by a computer 4, and this computer 4 is connected to each driving means via control wirings 5 and 6 shown in the figure. The computer 4 receives the information and the program via a storage device 8 connected by a wiring 7 and appropriate sensors.

The preheating zone 2 has a rectangular preheating chamber 9 lined with a thermally insulating material, on one end side of this preheating chamber 9 a charging port 11 is provided, while at the end of the side wall far from the charging port 11 a charging port 11 is provided. An outlet 12 is provided in the section. A fire bed extends into the preheating chamber 9 between the charging port 11 and the unloading port 12, and the charge 13 placed in the basket or on the pallet is passed over this fire bed from the charging port 11 to the unloading port 12. Move slowly. In front of the charging port 11, an airlock 14 is provided, which can be selectively opened to the charging port 11 of the preheating chamber 9 on the one hand by means of two doors 15 and 16, or to the outside air by means of the airlock door 16. can be closed to Both airlock doors 15 and 16 are provided with electrical or hydraulic drive means (not shown) for closing.

On the side wall of the air lock 14 facing the charging port 11, there is provided a pushing device 17 which can be actuated, for example, by hydraulic pressure, and when the air lock door 15 opens the air lock door 15, a pushing device 17 which can be actuated, for example, by hydraulic pressure, is provided. By means of this pushing device 17 it is possible to push past the charging port 11 and onto the grate of the actual preheating chamber 9, in which case all the charge 13 present on the grate can be pushed in the direction of the outlet 12 by a corresponding amount. move forward at the same time.

In order to remove the charge 13 from the preheating chamber 9, a further pushing device 19, which can likewise be operated, for example hydraulically, is installed on the side wall opposite the outlet 12.
A pushing device 19 is provided which, when activated, conveys the charge 13 present in front of the pushing device 19 from the grate in the preheating chamber 9 past the outlet 12 .

The furnace 3 likewise has a furnace chamber 21 lined with a thermally insulating material, the interior of which is accessible via a charging port 22 and a discharge port 23 . The charging port 22 of the furnace 3 is connected to the discharge port 12 of the preheating chamber 9, and a door 24 that can be operated by a drive means (not shown) is arranged between the two openings.
The interior space of the preheating chamber 9 can be selectively shut off from the interior space of the furnace chamber 21 by this door. To transfer the charge 13 from the preheating chamber 9 into the furnace chamber 21, only the door 24 is opened.

The outlet 23 is possibly connected to a further processing device for the workpieces, for which the outlet 2
The guide groove exiting from 3 is shown broken away.
The outlet 23 can also be selectively blocked by a suitable door 25.

The structure of the furnace 3 schematically shown in FIG.
This will be explained with reference to the drawings and FIG.

A hood 2 lined with a heat insulating material 28 is mounted on the square pedestal 27 via four pillars 26.
9 is placed, and this hood 29 is opened downward. The space defined by the lining 28 has a cylindrical profile with an arched ceiling 31.

A circular rotating grate 32 projects from below within the cylindrical space defined by the lining 28, and this rotating grate 32 is supported on a heat insulating support base 33. The rotating grate 32 is rotatably supported using suitable thrust bearings 34 about the vertical axis of the pedestal 23, which axis is connected to the lining 28.
It extends coaxially with the space defined by. In order to seal between the rotating grate 32 and the hood 29, a cylindrical fin 35 is arranged on the lower surface of the hood 29, and this fin 35 is filled with a shaft and has an opening toward the top. The ring groove 36 is connected to the rotating grate 32.
It is provided on the lower surface of the fin and extends laterally beyond the fin as shown in the figure. A furnace chamber 21 is formed by the combination of the rotating grate 32 and the hood 29.

An electric motor 37 with a reduction gear is fixed in the base 27 for driving the rotating grate 32, and its output gear 38 meshes with a gear 39 fixed to the grate 32. It is arranged coaxially with the rotation axis of the rotating grate 32. Further, a rotation angle transmitter 41 is meshed with the gear 39, and the electrical output end of this transmitter 41 is connected to the computer 4 via a coupling wire 42, so that the computer can transmit signals via the rotation angle transmitter 41, The rotation angle of the rotating grate 32 at any given time can be calculated.

A tube 43 with a closed end is inserted into the hood 29 below the ceiling 31, and a burner is pushed into the tube 43 to heat the atmosphere in the furnace. ing. In order to measure and control the physical and chemical parameters of the furnace atmosphere during the course of the process, known devices are provided and electrically connected to the computer 4, so that these devices can be individually I will not illustrate it.

The furnace equipment 1 described so far operates as follows. As soon as one place on the rotary grate 32 becomes empty due to the removal of one of the charges 13, a position signal of the rotation angle of the rotary grate 32 is output from the rotation angle transmitter 41 to the computer 4. Based on this, the computer 4 keeps the electric motor 37 with a reduction gear in operation until this empty storage space is placed opposite the charging port 22. As soon as the empty storage space reaches a position facing the charging port 22, the electric motor 37 with a reduction gear is stopped, the computer 4 operates the drive device for the door 24, and the door 24 is opened. Here, by communicating between the outlet 12 of the preheating chamber 9 and the charging port 22 of the furnace 3,
Similarly, the drive unit of the pushing device 19 is connected to the computer 4.
activated by Therefore, the charge 13a adjacent to the pushing device 19 is transferred from the grate in the preheating zone 9 to the outlet 12 and the charging inlet 22 by the pushing device 19.
The charge 13a is pushed through the grate 3.
It is positioned in the empty space above 2. After the pushing device 19 is pulled back to the initial position shown in FIG.
7 has been put into operation by the computer 4, the charge 13b waiting in the chamber of the airlock 14 can be pushed onto the grate in the preheating chamber 9.
As a result, the pushing device 17 advances all the charges 13 waiting in the preheating chamber 9 by one position at the same time, and again the arrangement shown in FIG. 1 is obtained, in which one charge An object 13a is located in front of the outlet 12.

After this, the pushing device 17 is pulled back and the computer 4 commands the closing of the airlock door 15. Now, after opening the airlock door 16, a new charge 13b can be charged into the empty airlock 14.

Fresh charge 13 transferred onto rotating grate 32
Regarding a, the timing of charging into the furnace 3 and the rotating grate 32
The angular position of this charge 13a above is stored in the memory 8 of the computer 4.

Since the computer 4 knows the time of charging into the furnace 3 and its rotational position on the rotating grate 32 for each charge present in the furnace 3 based on the above-mentioned process, the computer 4 uses this information and , using known sensors in the furnace atmosphere of the furnace 3, and on the basis of the physical and chemical parameters calculated by the computer 4 and the conditions to be achieved for each charge, the computer 4 determines the necessary Residence time can be calculated. Since the charge 13 present in the preheating chamber 9 has already been heated to the process temperature (for this purpose the preheating chamber 9 is heated by a predetermined heating element, not shown),
The charge 13 newly transferred into the furnace chamber 21 is
There is no influence on the process temperature for the immediately adjacent charge 13 that has already been in the furnace 3 for a long time.

As soon as the computer 4 determines, based on the information stored in the storage device 8, that the residence time has elapsed for one of the charges 13c to 13i present in the furnace 3, the computer 4 An electric motor 3 with a reduction gear drives the rotation of the rotary grate 32 until the charged material whose internal residence time has elapsed reaches the outlet 23.
7 is put into operation again. When the computer 4 confirms the arrival of the charge at this position using the rotation angle transmitter 41, the electric motor 37 with reduction gear is stopped;
Therefore, the rotating grate 32 remains stationary. After opening of the door 25, the treated charge 13 is withdrawn from the rotary grate 32 through the outlet 23 by means of a withdrawal device 44, which is partially shown broken away, in order to prepare it for the next treatment stage. I can do it. Thereafter, door 25 is closed again. It is obvious that the door 25 connected to the outlet 23 can also be an airlock door in order to prevent a large loss of atmosphere in the furnace.

The charging material 13a sent forward from the preheating chamber 9 by the above method can be placed in the empty storage space on the rotary grate 32, so that this storage space on the rotary grate 32 can be placed. The computer 4 puts the electric motor 37 with a reduction gear in an appropriate operating state until the electric motor 37 is in front of the charging port 22.

In this arrangement, the rotary grate 32 forms a conveying device for the charges 13c to 13i, which can be moved within the chamber of the furnace 3 along a closed track using the rotary grate 32.

The grate 32 which is self-evidently performed by the computer 4
The rotating grate 32 is controlled by an electric motor 3 with a reduction gear.
7, it is set to rotate continuously during the heat treatment process, to be held in the desired correct position by the computer 4 only during the actual charging and unloading steps, and then to be in continuous operation again. be able to. Furthermore, control is also set to operate the rotary grate 32 by rotating it to the left or right relative to the ejection port 23, depending on the position of the charges 13c to 13i to be carried out from the grate 32. Therefore, the charge can be carried out through the shortest route at any given time.

As shown in FIG. 4, which schematically shows the furnace 3, the charging port 2
2 and the outlet 23 can be located diametrically opposite with respect to the orbit provided by the rotating grate 32 or to the center of the chamber of the furnace 3. In addition, the embodiments described above also exhibit this condition. At that time, arrow 45
and 46 indicate the direction of movement of the charge during charging or unloading. The double arrow 47, on the other hand, indicates the selective direction of movement of the charge 13 within the chamber of the furnace 3. However, unlike the arrangement shown in FIG. 4, as shown in FIG.
Alternatively, it is also possible to arrange both the entrances and exits directly adjacent to each other.
Such an arrangement, schematically illustrated in FIG. 5, has the advantage that the rotating grate 32 does not have to move substantially, or only has to move a small amount, between removal and new charging. This is because the storage space that has been emptied due to removal is done this way. This is because it will be located immediately in front of or immediately next to the charging port.

The installation 1 makes it possible in the furnace 3 to simultaneously process in the furnace 3 even charges 13 which require different residence times. because,
This is because the charges 13 can be carried out independently of each other, and in this case, the control device constituted by the computer 4 stores necessary information regarding the position and residence time of each charge present in the furnace 3 in the storage device 8. is stored inside. As can be easily seen from the above description, during the removal of the charge 13 a heat treatment process for the remaining charges 13c to 13i present on the grate 32 proceeds. With proper planning, charges requiring different compositions of the furnace atmosphere can be created, for example by charging each charge when the most favorable atmosphere composition for the charge is obtained. It is even possible to process the two charges one after the other, while in order to take full advantage of the change in the atmospheric conditions for the different charges present in the furnace 3, these charges can be processed for a longer time. It is retained for a period of time.

[Brief explanation of the drawing]

FIG. 1 is a horizontal sectional view of an embodiment of furnace equipment for carrying out the method based on the present invention, and FIG.
Vertical sectional view of the original processing furnace of the furnace equipment shown in Figure 3.
The figures are a sectional view taken along the cutting line of the furnace shown in FIG. 2, FIG. 4 is a horizontal sectional view of another embodiment of the furnace, and FIG.
The figure is a horizontal sectional view of a further embodiment of the furnace. 2...Preheating area, 4...Control device, 8...Storage device, 9...Preheating chamber, 11...Charging port of preheating chamber, 1
3... Charge, 19... Pushing device, 21...
Furnace chamber, 22...Charging port, 23...Export port, 32...
...Fire bed (hodo), 32, 37...Transportation device, 41
...Position transmitter, 44...Drawer device.

Claims (1)

[Claims] 1. A method for heat treating a metal workpiece in a furnace chamber having a desired atmosphere, wherein the furnace atmosphere is heated to the respective process temperature, and the workpiece is placed in the furnace chamber. Each charge is charged and remains there for a predetermined period of time, while the state quantity and composition of the furnace atmosphere are simultaneously controlled by feedback control or open loop control, in which each charge has its own residence time in the furnace. A method for heat treatment of metal workpieces, characterized in that the workpieces are removed from the furnace chamber after a period of time has elapsed, regardless of other charges. 2. A method for heat treating metal workpieces according to claim 1, characterized in that each charge is preheated to the process temperature in the furnace chamber in a preheating zone before being charged into the furnace chamber. 3. A method for heat treating metal workpieces according to claim 1, characterized in that the physical and chemical parameters of the furnace atmosphere are kept constant over the processing time of one charge. 4 For each charge during its residence time in the furnace,
2. The method for heat treating a metal workpiece according to claim 1, wherein the residence time is calculated from the state quantity and composition of the atmosphere in the furnace and the shape of the workpiece for each charge. 5. A furnace chamber having a charging inlet for charging the charge into the furnace chamber and an outlet for carrying out the charge,
A grate located in the furnace chamber, on which the charge is placed during heat treatment, and a conveyor for transporting the charge through the charging port into the furnace chamber, through the furnace chamber and out of the furnace chamber. In a metal material heat treatment apparatus comprising a control device for controlling the state quantities and composition of the furnace atmosphere, a control device 4 having a storage device 8 is combined with the transfer devices 32 and 37. This control device controls each charge 1 placed in the furnace chamber 21.
3c to 13i, its position in the furnace chamber 21 and the required residence time of the charge 13c to 13i are stored in its memory, and the control device stores, after each residence time, Metal processing characterized by automatically controlling the conveying devices 32 and 37 so that the charges 13c to 13i whose residence time has elapsed can be carried out from the furnace chamber 21 by the conveying device regardless of other charges. Equipment for heat treatment of objects. 6. The transport devices 32, 37 are combined with a position transmitter 41, and this position transmitter is connected to the control device 4, and using the position transmitter,
Claim 5, characterized in that the control device 4 can detect the position of each charge 13c to 13i or the empty position of the charge in the furnace chamber 21. Heat treatment equipment for metal workpieces. 7. The conveying device 32, 37 in the furnace chamber 21 has a closed track along which the charges 13c to 13i can be moved. Heat treatment equipment for metal workpieces. 8 The charging inlet 22 and the unloading outlet 23 are
13i are located diametrically opposite each other with respect to the tracks for the loading ports 22 to 13i;
8. The heat treatment apparatus for metal workpieces according to claim 7, wherein the heat treatment apparatus extends to 3. 9. The heat treatment apparatus for metal workpieces according to claim 7, wherein the charging port 22 and the carrying port 23 are arranged adjacent to each other in the furnace chamber 21. 10 The grate 3 is rotatably supported in the furnace chamber 21 so that the conveying device forms a closed track.
2, the grate is selectively rotatable in one direction or the other, or in at least one direction, by means of a drive device 37 controlled by a control device 4, and a position transmitter 41 A patent characterized in that the position of each of the charges 13c to 13i on the grate 32 or the position of an empty space can be detected by the control device 4 using this position transmitter, which is connected to the floor 32. A heat treatment apparatus for metal workpieces according to claim 7. 11. The heat treatment apparatus for metal workpieces according to claim 5, characterized in that the conveying device is equipped with a pushing device 19 or a pulling device 44 for loading into or carrying out from a closed track. . 12 Preheating chamber 9 with its own charging port 11
The apparatus for heat treatment of metal workpieces according to claim 5, characterized in that is connected to the charging port 22 of the furnace chamber 21. 13 The control device includes a computer 4, which calculates each charge 13c to 1 present in the furnace chamber 21.
3i, the residence time in the furnace chamber 21 is calculated from the state quantity and composition of the atmosphere in the furnace and the workpiece shape of each charge 13c to 13i. A heat treatment apparatus for metal workpieces according to scope 5.