JPS5913403B2 - How to transport objects to be processed - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for conveying a workpiece, and particularly to a method for effectively suppressing the meandering phenomenon and phase shift phenomenon of a workpiece in a moving hearth type furnace such as a walking beam type or a walking hearth type. The present invention provides a method that can transport the objects while automatically correcting them.

Conventionally, moving hearth type furnaces such as walking beam type and walking hearth type have been used as furnaces that can transport objects to be processed continuously in the furnace and prevent predetermined processing. It is widely used for heating and heat treatment of materials such as plate materials, coil materials, and forged materials.

This moving hearth type furnace generally uses a moving hearth and a fixed hearth to combine the vertical movement and back-and-forth movement of the moving hearth, and repeats these movements to move the workpiece at a predetermined speed. The movement of the moving hearth, especially its vertical movement, is usually carried out by an eccentric cam (eccentric wheel) rotated by an electric motor.

On the other hand, one of the major problems that has been considered in the past with such moving hearth type furnaces is that during the transportation process of the workpieces that are continuously charged into the furnace, the group of workpieces is transported. This may cause a meandering phenomenon in which the material gradually protrudes to one side with respect to the direction, and a phase shift phenomenon may occur where the distance that the moving hearth actually moves and the distance that the material actually moves differs. .

There is also the problem that this phase shift becomes larger as it moves from the charging side to the extraction side.

In particular, this meandering phenomenon of the processed material is fatal in the operation of a moving hearth type furnace, because if it becomes severe, the processed material will eventually collide with the furnace wall, resulting in a serious accident that will lead to the shutdown of the furnace. Furthermore, even in the case of the above-mentioned phase shift phenomenon, a discrepancy occurs between the actual transport history of the processed material and the preset transport conditions, and the processed material on the extraction side is This causes various problems when extracting the data and transferring it to other devices.

For this reason, conventionally, when installing a furnace, it has been necessary to strictly align the phase of the eccentric cams that serve as a mechanism for vertical movement, which are arranged in large numbers at the bottom of the movable hearth, or to correct them by inserting shims. Based on the idea that the continuous curved movement of the floor, such as circular or elliptical shapes, causes a meandering phenomenon in the transfer of the processed material to and from the fixed hearth, the movement of the movable hearth is increased →
A method of repeating the rectangular motion of forward → descending and retreating has been widely adopted, but even with these measures, the meandering and phase shift phenomena described above have not yet been completely resolved, especially in furnaces. This phenomenon has become even more noticeable over the years of use, and in severe cases has caused serious problems such as furnace shutdown.

Furthermore, it is extremely difficult to match the phases of all of the numerous eccentric cams placed at the bottom of the moving hearth, and this has traditionally been considered a difficult task that requires a great deal of effort. Even if such a phase matching operation is performed, in reality, a slight phase difference still exists.

In view of the above circumstances, the inventors of the present invention conducted various studies on the meandering phenomenon and the phase shift phenomenon in the above-mentioned moving hearth type furnace, and as a result, they were able to completely elucidate the mechanism by which these phenomena occur.

Before explaining these elucidated mechanisms, in order to facilitate understanding of the present invention, we will first outline a walking beam furnace as an example of a moving hearth type furnace. refers to the entire heating furnace).

A movable beam 3 as a movable hearth is arranged in the heating furnace 1 along with a fixed hearth (fixed beam) 2, and these fixed hearth 2 and movable beam 3 constitute a known walking beam type conveyance mechanism. are doing.

Further, at the bottom of the movable beam 3, there are a plurality of eccentric cams (eccentric wheels) 4a, 4b, 4c that are simultaneously rotated by a drive mechanism (not shown) such as an electric motor.

4d, and the movable beam 3 can be moved up and down by rotation of these eccentric cams 4a to 4d.

Further, the movable beam 3 is provided with a normal horizontal movement mechanism such as a hydraulic cylinder 5, so that the movable beam 3 can be moved forward or backward in the transport direction.

Therefore, with this configuration, a predetermined amount of slab (workpiece) M that is continuously fed from a continuous casting device, etc.
The slabs M are loaded one by one into the heating furnace 1 using a pusher 6, and the slabs M placed on the fixed hearth 2 are lifted by the lifting of the movable beam 3, and then moved forward by the operation of the hydraulic cylinder 5. Then, by lowering the movable beam 3, it is placed on the fixed hearth 2 again.

The movable beam 3 enters under the fixed hearth 2 and returns to the initial position by a backward movement by the hydraulic cylinder 5.

By repeating this movement (rectangular movement in this case), the slab M moves forward one pitch at a time and is transported through the furnace, during which it is heated to a predetermined temperature, and then moved to the extractor 7. It is then taken out and supplied to a rolling mill or the like.

In such a moving hearth type furnace 1, meandering phenomena and phase shift phenomena of the workpiece M as described above occur, and it has been revealed that these phenomena progress as follows. .

That is, in order to support the movable hearth 3 on which a heavy workpiece M such as a steel piece is placed, and to move it up and down,
A large number of eccentric cams 4a l 4b + .
..., but if there is a phase difference between the eccentric cams 4a and 4a' between these rows, meandering will occur as shown in FIG.

2 schematically shows the A-A cross section in FIG. 1. First, in FIG. It is placed on floor 2.

When the phase of the eccentric cam 4a' on the left row in the figure is early, the left eccentric cam 4a' pushes up the movable beam 3 earlier than the right eccentric cam 4a, and therefore, at the delivery point, the phase of the eccentric cam 4a' is early. The movable beam 3 receives the slab M in an inclined state as shown in Figure 2, and the slab M is placed on the fixed hearth 2 at a position shifted to the right by △δ1/2 from the original delivery center. The receiver is placed on the movable beam 3.

In this way, the movable beam 3 supporting the slab M with a deviation of Δδ1/2 is moved forward (in a direction perpendicular to the figure) in the state shown in FIG. , the movable beam 3 is lowered, but since the phase of the left eccentric cam 4a' is early, as the eccentric cam 4a' rotates, the left side portion of the movable beam 3 lowers quickly, and as a result, as shown in FIG. As shown in d, the movable beam 3 is tilted and transfers the slab M to the fixed hearth 2 at the delivery point, so the slab M is further shifted to the left by △δ1/2 and is received by the fixed hearth 2. will be handed over.

(The inclinations of the movable beam 3 when ascending and descending are symmetrical and the same angle).

Therefore, the slab M eventually shifts to the left (meandering amount) by △δ1/2 + △δ1/2 - △δ1 in one lifting and lowering operation ((one conveyance cycle).

Then, the movable beam 3 is moved backward in the state of being located at the lowering end shown in FIG. ) is carried out in the next conveyance cycle [
By carrying out step (a""e in Figure 2), the deviation (△δ1) is further added up sequentially (the deviation when carrying out n transport cycles is n x △δ1), and here This causes a meandering phenomenon.

In particular, even if the initial deviation (Δδ1Y) is small, the amount of meandering becomes extremely large as the slab M is conveyed through the furnace, and in the past, this caused the serious problem described above. It had been triggered.

Here, we have described an example in which the phase of the left eccentric cam 4a' is early, but on the other hand, if the phase of the right eccentric cam 4a is early, the slab M will meander to the right in the figure. do(
This results in a shift in position.

Furthermore, even in the case of a phase shift phenomenon, the cause could be elucidated by analysis similar to that of the meandering phenomenon, as illustrated in FIGS. 3a to 3e.

That is, when the slab M is conveyed from left to right in the figure, for example, the eccentric cam 4b is transported more than the eccentric cam 4a.
If the phase of
In Fig. 3b], a phase shift of △δ2/2 occurs, and furthermore, at the transfer point when the movable beam 3 descends [Fig. 3d], an even more △δ
A phase shift of 2/2 occurs, and as a result, the movable beam 3
The slab M moves forward by an extra amount of △δ2 (=△δ2/2 + △δ2/2) for each lifting and lowering of For example, when the slab M is moved through the furnace by the movable beam 3, the amount of advance of the slab M increases (by n×Δδ2), and the closer it gets to the extraction side, the closer it gets. As the temperature increases, the position of the slab M shifts toward the extraction side with respect to the predetermined position.

In addition, in the figures, FIGS. 3a and b. c, d, and e respectively indicate the states at the descending end, delivery point, ascending end, delivery point, and descending end. Also, unlike the above, when the phase of the eccentric cam 4a is earlier than that of the eccentric cam 4b, is slab M
is a predetermined transfer amount △δ2 smaller each time the movable beam 3 moves up and down.Therefore, the more the slab M is transported in the furnace to the extraction side, the more the slab M becomes smaller relative to the predetermined position. This will cause it to shift toward the charging side.

Then, the phase difference of such an eccentric cam is caused in the conveying direction (in the furnace length direction, for example, between 4a and 4b) and in a direction perpendicular thereto (in the furnace width direction, for example, between 4a and 4a'). When this occurs, the above-mentioned phase shift phenomenon and meandering phenomenon of the slab M are caused in combination, and the meandering becomes more and more complicated, such as rotation of the slab M on the hearth, which causes damage to the furnace wall. This can easily lead to serious problems such as collisions.

In particular, with such a meandering mechanism and phase shift mechanism, even if the meandering and phase shift are initially caused by a slight phase difference between the eccentric cams, they will accumulate as they are transported in the furnace. For example, a small phase difference between eccentric cams that occurs due to long-term use of a furnace can cause a large meandering phenomenon or phase shift.
This clearly supports the conventional fact that the phase shift phenomenon occurs, and that the larger and longer the furnace, the more likely this problem will occur.

The present invention was completed based on such findings, and its gist is that the vertical movement of the movable hearth was conventionally performed only by the rotation of an eccentric cam in one direction. The rotation of the movable hearth is performed not only in one direction but also in the opposite direction, so that the vertical movement of the movable hearth due to the one-way rotation of the eccentric cam and the vertical movement of the movable hearth due to the rotation in the opposite direction are performed. By appropriately combining these, the material to be processed can be transported by the moving hearth. It has become possible to effectively suppress meandering and phase shift phenomena of objects to be processed, for which considerable efforts have been made, and to automatically correct them while conveying them.

That is, according to the method of the present invention, even if there is a slight phase difference between the eccentric cams, the meandering phenomenon and phase shift phenomenon that occur based on the mechanism shown in FIGS. 2 and 3 can be prevented. By giving the eccentric cam a rotation in the opposite direction (hereinafter referred to as reverse rotation) to the rotation direction of the eccentric cam that causes these phenomena (hereinafter referred to as forward rotation) (see Fig. 1). The eccentric cam 4as4b in...
・Gives rotation in the direction of the solid arrow and in the direction of the dashed arrow)
, this time will be induced in the opposite direction, and therefore the meanderings and phase shifts in opposite directions caused by the forward and reverse rotations of the eccentric cam will cancel each other out, By appropriately combining such forward rotation and reverse rotation, meandering and phase shift phenomena can be effectively suppressed or completely eliminated, and moreover, they can be corrected automatically and easily within the furnace.

For example, in FIG. 2, the eccentric cam 4 a +
When 4a' is rotated in the opposite direction, the phase of the right eccentric cam 4a becomes earlier, so the inclination of the movable beam 3 in Fig. 2 becomes the lower left one, which is completely opposite to that shown in the figure. The inclination of the movable beam 3 in Fig. 2 d is also completely opposite to the lower right one [in Fig. 2, d and d are interchanged], so the slab M moves △δ1 per lifting and lowering.
This results in a gradual shift (meandering) to the right.

Furthermore, if the eccentric cams 4a and 4b in the furnace length direction are reversely rotated in FIG. 3, the inclinations of the movable beam 3 in FIGS.
This time, there will be a delay of △δ2 for each lift.

Therefore, these eccentric cams 4a, 4a'4b...
If the movable beam 3 is raised and lowered by reverse rotation the same number of times as the number of times it was raised and lowered by normal rotation, meandering and phase shift phenomena can be almost completely eliminated.

As described above, according to the present invention, the problems of the meandering phenomenon and the phase shift phenomenon can be fundamentally and completely solved by the extremely simple operation of simply switching the rotation of the eccentric cams. Even if a phase difference exists between them or a phase difference occurs between them due to long-term use, the meandering and phase shift are automatically canceled during transportation in the furnace.
There are no longer any major accidents such as furnace shutdowns.

Furthermore, even if the furnace is installed in a state where a phase difference already exists between the eccentric cams in the furnace width direction or the furnace length direction, according to the present invention, the meandering phenomenon or Regardless of the degree of phase shift phenomenon,
Since these can be corrected, it is no longer necessary to perform extremely strict phasing of the eccentric cam when installing the furnace, as was the case in the past. performance could be significantly improved.

In addition, in the past, the adoption of motion of the movable beam 3 other than rectangular motion was denied because it would cause meandering phenomena and phase shift phenomena, but with the elucidation of these mechanisms as described above, By adopting an uninvented method as a countermeasure against lies, the motion of the movable beam 3 for transporting the workpiece can be not only rectangular motion but also circular motion, elliptical motion, or a combination of these motions. This means that it can be adopted as desired, and even if the object to be processed is conveyed according to these various movements, meandering phenomena and phase shift phenomena can be effectively suppressed.

The aspect of the combination of forward rotation and reverse rotation of the eccentric cam in the present invention as described above is such that a plurality of eccentric cams are arranged in the direction of transfer of the material to be processed (furnace length direction) or in the direction perpendicular thereto (furnace width direction). This will be determined as appropriate depending on the degree of phase difference between the two, the amount of meandering that can be allowed, the amount of phase shift, etc., but while the workpiece is being conveyed on one moving hearth, it must be rotated in the forward direction at least once. A combination with counter-rotation must be employed.

Therefore, such a combination generally includes one for each vertical movement (vertical movement) that alternates one forward rotation and one reverse rotation, and a combination for each predetermined number of times (or for a predetermined period of time). ) A combination that allows forward rotation and reverse rotation to be performed equally is preferably employed.

Incidentally, when the present inventors conveyed the workpiece through the furnace using a combination of forward and reverse rotations by switching alternately every rotation, there was no meandering or phase shift phenomenon in the workpiece at the extraction end. It was not recognized.

However, in addition to such a combination of equal forward rotation and reverse rotation, it is also possible to increase the number of times of elevation by reverse rotation than by forward rotation, or to reverse this, within the range of allowable meandering amount and phase shift amount. etc. are also possible.

Further, forward rotation and reverse rotation of such an eccentric cam can be easily achieved by known means such as switching a drive mechanism such as an electric motor that drives the eccentric cam (switching the direction of rotation of the electric motor). Further, such switching operation between forward rotation and reverse rotation can be performed automatically by an appropriate control device, or can also be performed manually.

Note that the present invention is by no means limited to the specific methods and means exemplified above, and various changes and improvements may be made based on the knowledge of those skilled in the art without departing from the gist of the present invention. It is something.

For example, the conveyance method according to the present invention uses an eccentric cam (eccentric ring)
As long as the movable hearth is moved up and down based on the amount of eccentricity of the hearth, it can of course be applied not only to the upper side but also to those in which the up and down movement is done via a lever. Needless to say, if it is a moving hearth type, it can be used in various types of furnaces such as heat treatment furnaces in addition to the upper heating furnace. In addition, there is also what is usually called a moving hearth in a narrow sense (walking berth type).

Furthermore, in addition to the conveyance system that uses a combination of a moving hearth and a fixed hearth, there is no problem with a mobile hearth type furnace that employs a conveyance system that combines two moving hearths.

Furthermore, in a so-called split hearth type furnace (for example, the one disclosed in Japanese Patent Application No. 54-65422, etc.), in which a plurality of such moving hearths are divided and arranged in the furnace length direction (transfer direction). The method of the present invention can also be effectively applied to such a case, but in this case, the present invention will be carried out for each divided moving hearth.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a walking beam heating furnace as an example of a moving hearth furnace, and FIGS. 2 a to 2 e are A-A in FIG.
FIGS. 3a to 3e are schematic cross-sectional views of the eccentric cams 4a and 4 in FIG. 1 for explaining the phase shift phenomenon, respectively.
b is a partial schematic diagram. 1: Heating furnace, 22 Fixed hearth, 32 Movable beam (moving hearth), 4a, 4a', 4b...: Eccentric cam (
Eccentric wheel), 5: Hydraulic cylinder.

Claims (1)

[Scope of Claims] 1. A walking beam type that performs predetermined processing while conveying the object to be processed by vertical and longitudinal movements of a moving hearth;
In a moving hearth type furnace such as a walking hearth type, the moving hearth is moved up and down by an eccentric cam, and the eccentric cam is rotated not only in one direction but also in the opposite direction. The object to be processed is transported by the movable hearth by appropriately combining the vertical movement of the movable hearth due to rotation in one direction and the vertical movement of the movable hearth due to rotation in the opposite direction. How to transport processed materials.