JPS6036549B2 - Material charging and extraction method for rotary hearth heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for inserting and extracting old and new materials to be heated when changing the pitch of the materials to be heated in a rotary hearth type heating furnace.

Generally, the charging and extraction of materials to be heated (hereinafter referred to as materials) in a rotary hearth type heating furnace (hereinafter referred to as a heating furnace) is carried out using a manipulator-type bagging machine and extraction machine. , or material size (caliber)
is constant, the material is always spread at a constant pitch (distance between the centers of the materials) on the rotating hearth, and therefore the charging machine and extractor are placed simultaneously at fixed positions at the charging and extraction ports, respectively. Activate.

However, in pipe manufacturing factories, etc., it is common to process materials of many different sizes in one heating furnace, and in this case, the above method of layering materials at a constant pitch does not allow for a pitch suitable for heat treatment of the largest size material. As a result, when heating small-sized materials, the utilization rate of the hearth is poor, resulting in poor productivity and fuel consumption. In order to overcome this drawback, it is conceivable to operate by changing the pitch for each size of material, but in this case, during the transition period when changing from old material of a certain size to new material of another size, the old material extracted Since the pitch and the pitch of the new material to be bagged are different, no matter how much the hearth rotates to match the pitch of either material, both the charging machine and the extraction machine remain in a fixed position. That becomes impossible. For this reason, in conventional variable pitch operation of heating furnaces, the rotation amount of the hearth is changed to the pitch of the new material, the charging machine is operated at the same constant position as the old material, and on the extraction side, the pitch of the new material and the old material is changed. Because the extraction position changes sequentially depending on the difference, the extraction port is enlarged and the extraction machine is moved laterally each time to extract the material. However, this method has the drawback that a wide extraction port is provided in the extraction section, where the temperature inside the furnace is highest, resulting in large heat loss, which cools down the heated material and worsens the working environment around the furnace. . The present invention aims to eliminate the above-mentioned conventional drawbacks, and provides a method for extracting materials in a rotary hearth heating furnace, which allows material changeover with less heat loss.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Figure 1 shows the state in operation when switching from old material A to new material B. In the figure, 1 is a heating furnace, and 2 is a heating furnace that moves and stops repeatedly by a predetermined rotation amount in the direction of arrow F around the center 0. The hearth, 3 is the furnace wall, and 4 is the bag inlet provided on the furnace wall, which is approximately at the maximum pitch of the materials while it is open.

Reference numeral 5 denotes an extraction port provided in the furnace wall, and its size is such that it is possible to extract the maximum size material while the port is closed.

Reference numeral 6 denotes a partition wall provided from the furnace ceiling toward the hearth, which has a heat-insulating function between the charging port and the extraction port.

7 is a material extractor, which is fixed on the foundation and operates at a fixed position.

Reference numeral 8 denotes a material charging machine, which has a material charging function and can perform lateral movement in the direction of arrow G around the center ◯, and has a driving device 8a for charging and lateral movement.

The figure shows a state in which the charging machine 8 is at the reference position closest to the extraction machine, and this position is defined as the center line OM of the bagging machine.
The angle formed by the center line ON of the extractor and the center line ON of the extractor is 8 (radians).
Further, 9 indicates the center line of the hearth, and r is its radius. Hereinafter, the pitch of the material, the amount of rotation of the hearth, the moving distance of the material, the moving distance of the bagging machine, etc. will all be expressed by the arc length on the hearth center line 9. Therefore, the reference position OM
In the above, the total distance L that the material placed on the hearth 2 moves until it reaches the extraction position is expressed by the following equation. L=(
2 10) r ......Formula a Figure 2 is a system explanatory diagram of the electrical control system used in conjunction with the device shown in Figure 1.
1 and 12 are material pitch setting devices; S, and S2 are output signals thereof; and 13 is a signal switching device that selects one of the signals S, S2 as the old pitch signal S3 and the other as the new pitch signal S4.
This is a device that reversely switches the combination of signals S, S2 with respect to signals S3, S4 based on output signals S, 7 of a discriminator 21, which will be described later.

S5 is a hearth movement detection signal, which detects hearth movement (start/stop) from an appropriate hearth movement detector through a shaping intensifier (not shown).
It is sent as one pulse at a time. S6 is a material conversion command signal, which is issued by an appropriate device after the last old material is charged and when the hearth moves an appropriate number of times (in this embodiment, twice) at the old pitch and stops. Reference numeral 14 denotes a gate which opens in response to the material slit command signal S6 and outputs signals S and 7 from the discriminating device 21, which will be described later.
, and S7 is its output signal.

15 is a counter for integrating the output signal S7, and S8 is a hearth movement number signal.

On the other hand, S9 is a material charging detection signal, which is sent as one pulse per charging from a suitable material bagging detector via a shaping intensifier (not shown). 16 is a gate which is opened and closed in the same manner as the gate 14 by the signals S6 and S, 7, and its output signals S, o are integrated by a counter 17 to produce charging number signals S, . is given to the arithmetic unit 18 as .

The arithmetic unit 18 receives input signals S3, S4, S8, S, . Based on the calculation formula b below, calculate the distance ×n from the reference position OM of the charging machine 8, and if the value is positive or zero, emit a lateral movement heavy signal S, 3 according to ×n, If it is negative, a hearth movement command signal S, 4 is issued. Xn=NP-nQ ・
.........Formula b) N = Number of hearth movements after material switching command (signal S8) n = Number of new materials charged (signal S,.) P = Old pitch (signal S3) Q=new pitch (signal S4) - The meaning of the above equation will become clear when compared with the explanation of the operation shown in FIGS. 3 and 4, which will be described later.

Reference numeral 19 denotes a charging machine control device that generates output signals S, 5 for controlling the charging device drive device 8a, and a hearth control device that generates output signals S, 6 for controlling the two-way rotary hearth drive device.

On the other hand, 21 is a discriminator, which has an internal setting signal corresponding to the total distance L (see formula a), and determines the old pitch P based on the old pitch signal S3 and the hearth movement count signal S8 after the material change command.
The product of the number of hearth movements N and the total distance L is compared, and if the two become equal, that is, in this embodiment, when the first new material & reaches the extraction port 5, the output signal S. It emits one. Although the control system for the extractor 7 is omitted in Fig. 2, the extractor 7 is controlled so that it extracts one material at a time each time the hearth is stopped using a three-way method without moving laterally. . Next, a series of material charging/extracting methods when switching materials using the above-mentioned charging machines will be explained mainly with reference to FIGS. 2 and 3.

Now, under the movement of the hearth equal to the old pitch P, the charging machine 8
is charging the old material A at the reference position ○M, and at the same time, the extractor 7 is extracting the old material A at the extraction port.

From this pillow state, the material is changed in the following order).
Note that the pitch setter 11 is set to the old pitch P, the pitch setter 12 is set to the new pitch Q, and the signal switching device 13 sets the output signal S as the old pitch signal S3 and the output signal S2 as the new pitch signal S4. Suppose that it is in the state of transmitting. Further, the new pitch Q is smaller than the old pitch P, and both P and Q are an integer fraction of the total distance L. '1} Last old material A
When z is charged and the hearth 2 is moved twice, a material switching command signal S6 is sent and the gates 14 and 16 are opened.

Counters 15 and 17 indicate the number of hearth movements N after the material switching command.
= 0, the cumulative signal S8, S, . is sent to the arithmetic unit 18, and the arithmetic unit performs the following calculation using the equation b. ×. =0xP-0xQ:0, that is, a lateral movement amount signal S,3 corresponding to Xo = 0 is sent to the charging machine control device 19, and the bagging machine 8 moves horizontally based on the output signal S,5. The new material B is charged at the reference point Higami on the hearth, which is a tsubo away from the final material Az position at the reference position OM.

[Fig. 3a] [2] By charging the material, the counter 17 becomes n.
=1 bag number signal S, . is sent to the arithmetic unit 18, and the arithmetic unit performs the following calculation.

X,=0×P−Q However, since X, is negative, the hearth movement command signal S,4 is sent, and the hearth control device 20 uses the output signal S,6 to move the hearth by the pitch P according to the old pitch signal S3. move.

[Figure 3b] {3} Due to the movement of the hearth, the counter 15 becomes N.
=1 hearth movement count signal S8 is sent to the computing unit 18, and the signals S, . Then, the following calculation is performed.

X,=P−Q The charging machine control device 19 moves the charging machine 8 from the reference position OM to the position of the distance X, using the lateral movement amount signal S,3 corresponding to the above Charge.

[Figure 3b] {4) Counter 17 is n=2 due to material charging
The diamond-shaped number signal S, . The arithmetic unit 18 performs the following arithmetic operation.

X2=P-2Q However, since X2 is negative, the hearth moves by the pitch P in the same manner as in [2'.

[Figure 3c]'5} n= by counters 17 and 15
2, N=2 output signals S, . , S8, the following calculation is first performed.

X2=The single-winged rice-filling machine 8 moves laterally from the reference position OM to a position a distance X2, and the new village fee B2 is placed in a bag.

[Fig. 3C] Next, the bag number signal S, . The following calculation is performed, and another new village charge B3 is charged at a distance X3 from the reference position OM [Figure 3C] X3 = -3Q '6' or less. As long as the new material Bn can be arranged at a pitch Q between 1 and 2, the new material Bn is introduced one by one per stop of the hearth, and at the same time the old material A is extracted one by one at the extraction port.

{7) When the reference point on the hearth reaches the extraction position [Fig. 3 d], NP=L, so the discriminator 21 outputs the output signal S,
7, the signal switching device 13 operates and the hearth control device 2
The signal S3 given by 0' is switched to the output signal S2 of the pitch setter 12 corresponding to the new pitch Q, and the hearth movement amount thereafter becomes the new pitch Q.

Further, the gates 14 and 16 are closed by the output signals S and 7, and the computing unit 18 does not perform any calculations thereafter. On the other hand, in this state, the charging machine 8 is at the reference position OM, so the charging machine 8 will be at this position from now on. It is fixed and the material change is completed. '8' When switching to another material with a pitch R, set the pitch R in the pitch setting device 11 and send the material switching command signal S6
All you have to do is give.

The above explanation was based on the case of P>Q, but in the case of P<Q, as shown in Fig. 4, the reference point Higami, X, becomes empty, so there is no charging [Fig. When moving, B rhombus is placed in the position where Charging is performed, and the old material is extracted one by one at the extraction port. FIG. 4d shows the state in which the reference point has reached the extraction position. As is clear from the above explanation, the amount of rotation of the hearth at the extraction port is equal to the bed pitch P of old material A before and during the material change, and is equal to the bed pitch Q of new material B after the change. Therefore, since each material reaches the same position at the extraction port, the extractor 7 can be operated at a constant position and the material can be changed.

Therefore, the extraction port 5 can be made to the minimum size that allows material to be extracted, and heat loss at the extraction port is reduced. Further, even if the charging port 4 is large, the inside of the furnace is at a low temperature and is thermally isolated from the extraction side by the partition wall 6, so heat loss is not a problem and the extraction material is not cooled. In the above embodiment, the first new material Ao was charged at the reference point Higami on the hearth, but charging may be started from another position, such as the position A, for example.

Further, the reference position OM of the charging machine 8 may be set to a position other than the position near the extraction port described above, but in this case, the position of the It is necessary to change the judgment conditions. Furthermore, in the above embodiment, the calculation unit 18 was used to perform calculations for each hearth movement and material charging, and the lateral movement and charging of the charging machine 8 were performed. For each hearth displacement equal to the least common multiple of each pitch of (e.g. P=2
00 Yanagi, if Q = 120 ribs, the same pattern will be repeated (every time the hearth moves 3 times at the old pitch), so calculate the amount of movement in advance and use other methods such as program control. The movement and charging of the loading machine may be performed depending on the control method.

As explained above, in this invention, when changing materials, the bagging machine is moved laterally to perform charging, and the extractor is always operated at a fixed position, so the extraction opening can be set to 4. There is little heat loss at the mouth, and there is no cooling of components at the extraction mouth or deterioration of the environment around the furnace.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view of a rotary hearth type heating furnace and attached equipment for carrying out the method of the present invention, FIG. 2 is a control system explanatory diagram, and FIG. This figure and FIG. 4 are explanatory diagrams developed on the center line of the hearth in FIG. 1 as seen from inside the furnace. 1. ．． ．． ．． ．．・Heating furnace, 2... Hearth, 3...
...Charging port, 5...Extraction port, 7...Extractor,
8...Bagging machine, 11,12...Pitch setting device,
13... Signal switching device, 14, 16...
・Gate, 15, 17... Counter, 18... Arithmetic unit, 19... Charging machine control device, 20...
... Hearth control device, A... Old material, B...
・・Shinmura fee, H……Reference point. Fig. ′ Younger brother Z Fig. 3 Fig. 4

Claims (1)

[Claims] 1. When switching from an old material to a new material with a different loading pitch in a rotary hearth type heating furnace, the amount of rotation of the hearth remains the same as the old pitch, and the material charging device is moved laterally at the charging port. , charge the new material into the new pitch using the appropriate indexed position by the old pitch on the hearth as a reference point, and when the above reference point reaches the extraction port position, switch the hearth rotation amount to the new pitch, and the material extraction device A method for charging and extracting materials in a rotary hearth type heating furnace, which is characterized in that it is always operated at a fixed position.