JPH10332466A - Adjustment of attracting weight by lifting magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adjusting method of attraction weight with a lifting magnet that can accurately adjust the weight of magnetic material such as scrap material attracted to the lifting magnet to a target weight in a high efficiency. SOLUTION: The output voltage of a lifting magnet is set at the maximum value VH. A magnetic material of a weight WE exceeding a target weight S is attracted and suspended. Then, the output voltage is quickly decreased in a steep gradient pattern V1 A, and the magnetic force is quickly decreased. Thus, the magnetic material is quickly dropped from the lifting magnet. After the attracted weight has reached a specified switching weight WK exceeding the target weight S, the output voltage is dropped at a less gradient pattern V1 B, and the magnetic force is gradually decreased. Thus, the magnetic material is gradually dropped from the lifting magnet. When the attracted weight of the magnetic material has reached the target weight S, the output voltage is immediately returned to the maximum value VH, and the dropping of the magnetic material is blocked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a magnetic force of a lifting magnet by controlling an output voltage or an electric current while detecting an adsorption weight of a magnetic material (for example, a scrap material put into an electric furnace). The present invention relates to a method for adjusting the weight of a magnetic material, which adjusts the weight of a magnetic material sucked and supported by a lifting magnet.

[0002]

2. Description of the Related Art Generally, in an electric furnace factory, a scrap material, which is a magnetic material, is charged into an electric furnace using a lifting magnet. That is,
By lifting and lowering the excited lifting magnet in the scrap material storage area, a predetermined amount of the scrap material is sucked and suspended, and after moving the lifting magnet to the electric furnace, the magnet is demagnetized or reversely excited to generate scrap. The material is dropped from the lifting magnet into the electric furnace.

[0003] The amount of scrap material charged into an electric furnace at one time is determined according to the capacity of the electric furnace. On the other hand, the weight of the scrap material adsorbed by the lifting magnet can be arbitrarily adjusted by controlling the magnetic force of the lifting magnet. The magnetic force control is
This is performed by controlling the output voltage or current to the lifting magnet.

Therefore, in general, the magnetic force of the lifting magnet is set to a target weight set in accordance with the capacity of the electric furnace (the weight of the scrap material which is optimally put into the electric furnace, and has a certain allowable range). In general, the scrap material is adjusted so as to be capable of adsorbing a scrap material having a weight corresponding to the weight of the scrap material, and the lifting material is used to suck and suspend and transfer the scrap material.

However, even when the magnetic force of the lifting magnet is constant (when the voltage or current is constant), the shape and material of the scrap material (for example, a return material, a chopper material, a roller material, Because of the pig iron material, etc., the weight of the scrap material to be absorbed is not constant, and large variations occur. Therefore, no matter how the output voltage and current are set, it is necessary to always adsorb the scrap material with the target weight. In practice, it is impossible.

[0006] Such a problem is common to the case where various magnetic materials including scrap materials are lifted by a lifting magnet, and in fact, there is a strong demand for a solution.

Therefore, the inventor of the present invention first calculates the magnetic force of the lifting magnet while detecting the weight of the magnetic material to be attracted.
An attempt was made to adjust the weight of the magnetic material sucked and supported by the lifting magnet by controlling the output voltage or current.

That is, a magnetic material having a weight exceeding a target weight is attracted and suspended by a lifting magnet having a maximum magnetic force, and then the magnetic force is reduced, and the magnetic material is sequentially dropped from the lifting magnet to attract the magnetic material. When the weight reaches the target weight, return to the maximum magnetic force,
By stopping further dropping of the magnetic material, the adsorption weight of the magnetic material is adjusted to the target weight.

[0009]

However, according to such a method for adjusting the weight of the attracted material, the electric furnace is supported by attracting and supporting the magnetic material of the target weight regardless of the suspending conditions such as the shape and the material of the magnetic material. However, in order to accurately adjust the adsorption weight, there is a problem that the adjustment time is extremely long and the working efficiency is extremely poor.

In other words, when the decreasing gradient of the magnetic force is increased, that is, when the voltage or current is abruptly reduced, when the magnetic material reaches a certain value, the magnetic material starts to drop rapidly and in large quantities from the lifting magnet. , The amount of the fall cannot be properly controlled. As a result, at the time when the magnetic material is restored to the maximum magnetic force, the weight of the magnetic material remaining in the lifting magnet may be significantly lower than the target weight. Such a problem is extremely remarkable particularly when the weight of the magnetic material per piece is large.

Therefore, in order to accurately adjust the adsorption weight, it is necessary to gradually decrease the magnetic force, that is, the voltage or current, with a gentle gradient, and to gradually drop the magnetic material little by little. In this case, the time from when the magnetic force starts to decrease to when the attracted weight reaches the target weight becomes extremely long, and the working efficiency becomes extremely poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the weight of a magnetic material such as a scrap material adsorbed on a lifting magnet can be accurately and efficiently adjusted to a target weight. It is an object to provide an adjustment method.

[0013]

According to the present invention, there is provided a method for adjusting an attraction weight by a lifting magnet by controlling the magnetic force of the lifting magnet by an output voltage or current while detecting the attraction weight of a magnetic material. ,
When adjusting the weight of the magnetic material sucked and suspended by the lifting magnet, in order to achieve the above object, in particular, the lifting magnet having the maximum magnetic force is used to attract and suspend the magnetic material having a weight exceeding the target weight by suction. It is proposed to control the magnetic force by any of the following methods.

That is, in the first method, while the magnetic force is reduced steeply, the adsorbed weight of the magnetic material is rapidly dropped and reduced, and the adsorbed weight reaches a predetermined switching weight exceeding the target weight. Thereafter, the magnetic force is gradually decreased so as to gradually drop the magnetic material, and the magnetic material is restored to the maximum magnetic force when the attracted weight of the magnetic material reaches the target weight.

In the second method, the magnetic force is reduced at a steep gradient until the magnetic material starts falling from the lifting magnet, and the start of the magnetic material falling is grasped by the change in the adsorption weight. After that, the magnetic force is gradually decreased so as to gradually drop the magnetic material, and is restored to the maximum magnetic force when the attracted weight of the magnetic material reaches the target weight.

In the third method, the first method or the second method is selected according to the difference between the actual weight absorbed by the maximum magnetic force and the target weight. In other words, when the difference between the actual attracted weight due to the maximum magnetic force and the target weight exceeds a predetermined selection reference value, the magnetic force is steeply reduced, and the magnetic material is rapidly dropped and reduced. After the adsorption weight reaches a predetermined switching weight exceeding the target weight, the magnetic force is gradually decreased to gradually drop the magnetic material, and when the adsorption weight of the magnetic material reaches the target weight. , To return to the maximum magnetic force,
Further, when the difference between the actual adsorption weight and the target weight due to the maximum magnetic force is equal to or less than the selection reference value, the magnetic force is reduced at a steep gradient until the magnetic material starts to fall from the lifting magnet. After the start of dropping of the magnetic material is grasped from the change in the weight of the magnetic material, the magnetic force is gradually decreased to gradually drop the magnetic material, and when the weight of the magnetic material reaches the target weight. , To return to the maximum magnetic force.

In the present invention, the target weight means not only the weight itself that is optimal for the conditions for loading the magnetic material (the conditions for charging the electric furnace, etc.), but also includes an allowable range based on the weight. It is. Further, the maximum magnetic force does not mean a magnetic force at the capacity limit of the lifting magnet, but means a magnetic force necessary and sufficient to be able to attract and suspend a magnetic material having a weight exceeding the target weight.
It is appropriately set according to the target weight. Of course,
Depending on the target weight, the magnetic force may reach the capacity limit.

[0018]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Or, it will be described with reference to FIG. In each of the embodiments described below, the scrap material to be charged into the electric furnace is attracted and suspended by a lifting magnet configured to adjust the magnetic force by voltage control. According to an example in which the adsorption weight is adjusted by the method of the present invention.

The suction according to the present invention in the first embodiment is described.
In the method of adjusting the wearing weight (hereinafter referred to as "first method")
On the lifting magnet side (crane)
Scrap material sucked and suspended on the footing magnet
Incorporates an appropriate load meter that detects the weight (adsorption weight) W
Then, based on the value detected by the load cell, the output voltage V decreases.
By performing the downward control, the adsorption weight W is set in advance.
Adjust to the target weight S. The target weight S is an electric furnace.
Scrap material weight per one shot to be fed into
(Hereinafter referred to as “reference target weight S_S")
Tolerance (S _S± ΔS) (second and
The same applies to the third embodiment).

First, the voltage command value is set to the maximum V _H , that is, the magnetic force of the lifting magnet is set to the maximum, and the lifting magnet is raised and lowered in the scrap material storage area by the crane operation to lift the scrap material. Note that the maximum magnetic force obtained by the maximum voltage V _H means a magnetic force necessary and sufficient to be able to attract and suspend a magnetic material having a weight exceeding the target weight S, as described at the beginning.

At this time, the maximum voltage V _H when the scrap material is lifted is determined by the magnetic force obtained by this, that is, the weight of the scrap material lifted by the lifting magnet by the maximum magnetic force (hereinafter referred to as “initial adsorption weight W _E ”). Set to exceed. Whether the initial adsorption weight W _E may be Uwamaware how the target weight S, it is preferable to determine in accordance with the variation weight W _D when the scrap material is lifted under the voltage V _H. For example, the maximum voltage V _H is the design, the reference target weight S weight was added variation weight W _D equivalent to _S (S _S + W _D) necessary and sufficient magnetic scrap material hoist (up force) is It is preferable to set it so that it can be obtained. In general, the upper and lower tolerance value of the reference target weight S _S ([Delta] S) is smaller than the variation weight W _D.

Next, while the lifting magnet is held at the lifting position, the output voltage V is changed based on the value detected by the load meter based on the first control patterns (voltage drop patterns) V _1A , V _1A , V _1A , V _1A and V 1 shown in FIG. Control according to _1B .

That is, the output voltage V is changed to the maximum voltage V_HOr
Steep slope pattern V_1ATo reduce the magnetic force rapidly
Let me do it. When the voltage V drops to a certain extent,
Of scrap material adsorbed on the magnet
Part will start to fall, and after that, as the voltage drops
The amount of scrap material falling increases. And heels
Sudden voltage drop by the lifting magnet
The switching weight W set in advance by decreasing the wearing weight W_KReached
Continue until the load is detected by the load cell. this
Switching weight W_KIs the maximum voltage V_HActual adsorption when
Weight W_EAnd the target weight S
But the switching weight W_KIs set to a value extremely close to the target weight S
The switching weight W_KAt the stage when
Slow voltage drop pattern V_1BSwitch to
Also, the amount of scrap material dropped did not decrease and the adsorption weight W
There is a possibility that the weight may fall below the target weight S. Therefore,
Replacement weight W_KMeans that there is no
Key weight W_DIs appropriately set in consideration of That is,
Replacement weight W_KSets the voltage drop pattern to the steep slope pattern V _1A
To gentle slope pattern V_1BSwitch to
Adsorption weight W without dropping rate of crap material immediately
Is the switching weight W_KIs less than the target weight S
It is set so that it does not fall below.

When the load meter detects that the suction weight W has decreased to the switching weight W _K , the voltage drop pattern is switched to one having a gentle gradient, and the voltage V is gradually lowered. With such a slow voltage drop, the amount of scrap material falling decreases, and the scrap material falls gradually. It is preferable that the gentle voltage drop gradient (voltage drop amount per unit time) is set according to the properties (materials and the like) of the scrap material. For example, a plurality of types of voltage drop patterns set according to the properties of each scrap material such as roller material, pig iron material, return material, chopper material, etc. are prepared in advance, and the voltage drop patterns according to the properties of the scrap material are prepared. Is preferably selected.

When the attracted weight W of the lifting magnet gradually decreases and reaches the target weight S, the voltage drop control is completed, and immediately, the voltage command value is set to the maximum _VH and the lifting magnet magnetic force is returned to the maximum. To prevent further scrap material falling. By the way, when the voltage V is dropped at a steep gradient, even when the load meter detects that the target weight S has been reached, the fall of the scrap material is not immediately stopped even if the voltage is set to the maximum V _H , and the adsorption is not performed. The weight W may be lower than the target weight S. But,
As described above, when the voltage V is gradually decreased,
Since the scrap material is gradually dropped, the target weight S
When the load meter detects that the load value has reached (the upper limit value (S _S + ΔS)), if the voltage is set to the maximum V _H , the falling of the scrap material is quickly stopped, and the adsorbed weight W is reduced to the target weight S (lower limit value). (S _S -ΔS)), and the adsorbed weight W is reliably adjusted to the target weight S (allowable range (S _S ± ΔS)).

As described above, according to the first method, the first weight adjusting step of reducing the adsorbed weight W of the scrap material on the lifting magnet from the initial adsorbed weight W _E to a constant switching weight W _K, and the switching weight W _K Since the first weight adjustment step is performed by abrupt voltage drop control and the second weight adjustment step is performed by a slow voltage drop control, the first weight adjustment step is performed by a slow voltage drop control. Weight adjustment can be performed more accurately than when the entire weight adjustment process is performed by rapid voltage drop control, and the weight adjustment time is significantly longer than when the entire weight adjustment process is performed by slow voltage drop control. Can be shortened to
Work efficiency can be improved.

That is, in the first weight adjustment step,
Even if the adsorption weight W is as below switching換重amount W _K, if there is no fall below target weight S, the weight adjustment,
Since there is no problem, the time required for the step can be reduced as much as possible. That is, in the first weight adjusting step, since the sharp decrease in sudden drop that is adsorbed by weight W of the scrap material by a rapid drop in voltage is performed, even if there is large variation in the initial adsorption weight W _E, the The time required for one weight adjustment step (the time until the start of the second weight adjustment step) is short and substantially constant. The adsorption weight W at the end of the first weight adjustment step is the switching weight W _K or slightly lower than the switching weight W _K , and the degree of the variation is extremely smaller than the degree of the variation of the initial adsorption weight W _E. In other words, the adsorbed weight W at the start of the second weight adjustment step is always substantially constant and close to the target weight S even when the initial adsorbed weight W _E has a large variation. As a result, in the second weight adjustment step, the time required for the adsorbed weight W to reach the target weight S is shortened, despite the slow voltage drop for accurate weight adjustment. Therefore, even if the initial adsorbed weight W _E varies greatly depending on the shape of the scrap material and the like, the adsorbed weight W can always be accurately adjusted in a short time.

Further, the method for adjusting the adsorption weight according to the present invention in the second embodiment (hereinafter referred to as "second method").
Is to lift the scrap material by the lifting magnet with the voltage command value being the maximum V _H , and to control the voltage V while detecting the suction weight W with the load meter on the lifting magnet side, so that the suction weight W is set to the target weight S.
The steep voltage drop pattern V _2A
The configuration is basically the same as that of the first method except that the switching reference to the gentle gradient voltage drop pattern V _2B is different.

First, a scrap material having a weight exceeding the target weight S (initial suction weight W _E ) is sucked and suspended by setting the voltage command value to the maximum V _H. This maximum voltage V _H is set in the same manner as in the first method, but the initial adsorption weight W _E
Is preferably set to be smaller than in the case of the first method.

Next, in a state where the lifting magnet is held at the lifting position, the output voltage V is changed based on the adsorption weight W detected by the load meter in the second control pattern (voltage drop pattern) shown in FIG. Control is performed according to V _2A and V _2B .

That is, the output voltage V is decreased from the maximum voltage _{VH in a} steep gradient pattern _V2A , and the magnetic force is rapidly reduced. When the voltage V drops to a certain degree, a part of the scrap material attracted to the lifting magnet starts to fall. The start of the drop can be detected as a change (decrease) in the adsorption weight W by the load meter. In other words, the point in time when the load meter detects that the adsorption weight W has decreased by the preset weight (hereinafter referred to as “drop determination weight ΔW”) is defined as the drop start point. It is preferable to set the fall determination weight ΔW as small as possible, but generally, it is preferable to set it in consideration of the detection error of the load meter, the variation of the load detection value due to the vibration of the runway, and the like. .

When the falling of the scrap material is started, that is, when the load meter detects a decrease in the attracted weight equal to or more than the drop judgment weight ΔW, the voltage drop pattern is changed to the steep gradient pattern V _2A as in the first method. switching to low-gradient pattern V _2B from going slowly lowers the voltage V. With such a slow voltage drop, the amount of scrap material falling decreases, and the scrap material falls gradually. This slow voltage drop gradient (voltage drop per unit time)
Is preferably set according to the properties (material, etc.) of the scrap material. For example, a plurality of types of voltage drop patterns V _2B set according to the properties of each scrap material such as a roller material, a pig iron material, a return material, a chopper material, etc., are prepared in advance (stored in the control device), and the scrap material is prepared. It is preferable to select the voltage drop pattern V _2B according to the properties of the voltage drop pattern V _2B .

When the attracted weight W of the lifting magnet gradually decreases and reaches the target weight S, the voltage drop control by the second control patterns V _2A and V _2B is completed, and the voltage command value is immediately increased to the maximum. As _VH , the lifting magnet magnetic force is returned to the maximum, and further scrap material is prevented from falling.

As described above, according to the second method, as in the case of the first method, the first weight adjusting step of starting the falling of the scrap material sucked by the lifting magnet, Divided into a second weight adjustment step for reducing the weight W to the target weight S, the first weight adjustment step is performed by a sharp voltage drop control, and the second weight adjustment step is performed by a slow voltage drop control. Therefore, the weight adjustment can be performed more accurately than when the entire weight adjustment process is performed by the abrupt voltage drop control, and the weight adjustment time can be adjusted as compared with the case where the entire weight adjustment process is performed by the slow voltage drop control. Can be greatly reduced, and work efficiency can be improved. Especially,
The second method is suitable when the difference D between the initial adsorbed weight W _E and the target weight S is small.

Further, the method for adjusting the adsorption weight according to the present invention in the third embodiment (hereinafter referred to as “third method”).
The first method and the second method depend on the magnitude of the initial adsorption weight W _E.
It is devised to select the method and, because the dispersion of the initial adsorption weight W _E is extremely large, for example,
As in the case where the initial adsorption weight W _E is less than the switching weight W _K and it is difficult to apply the first method, or conversely when the difference between the two W _E and S is large and the weight cannot be adjusted efficiently by the second method, Even if a situation where suitable weight adjustment cannot be performed in the second method occurs, weight adjustment can be performed efficiently.

That is, in the third method, the actual adsorption weight W _{E of} the maximum magnetic force at the maximum voltage V _H , that is, the initial adsorption weight W _E of the scrap material attracted and suspended by the lifting magnet with the maximum voltage V _H. If the difference D from the target weight S (mainly the reference target weight S _S ) exceeds the preset selection reference value W _S , the weight adjustment is performed by the first method, and if the difference D is less than the selection reference value W _S. Adjusts the weight by the second method. That is, in the former case, the voltage V is controlled to drop by the first control patterns V _1A and V _1B shown in FIG. 1, and in the latter case,
The voltage V is controlled to drop by the second control patterns V _2A and V _2B shown in FIG. 2, and in any case, when the adsorbed weight W reaches the target weight S, the voltage V is returned to the maximum voltage V _H. The specific control contents in each case are as described above, and thus are omitted here. By the way, this selection reference value W _S is such that the initial adsorption weight W _E is W _E = S _S + W
_In the case of _S , it is preferable to set appropriately as long as the weight adjustment can be performed accurately and efficiently by both the first method and the second method.

Therefore, according to the third method, the scraper
Initial adsorption weight W depending on the shape of _ELarge variation
The initial adsorption weight W_EAccording to the size of
The best method (first method or second method)
The adjustment of the adsorption weight W is always accurate and efficient
Can do it.

It should be noted that the present invention is not limited to the above-described embodiments, and can be appropriately improved and changed without departing from the basic principle of the present invention. For example, magnetic force control can naturally be performed by current control in addition to the above-described voltage control, and the method is exactly the same. Further, in any of the first to third methods, in addition to the case of automatic control, it is also possible to control a part or all of the method by an artificial operation. Of course, the present invention can be applied not only to the above-described scrap material but also to any magnetic material as long as a lifting magnet can be used.

[0039]

As will be easily understood from the above description, according to the method of the present invention, the weight of the magnetic material to be attracted by the lifting magnet can be adjusted accurately and efficiently, and the handling accuracy by the lifting magnet can be improved. ,
Efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a control pattern diagram of a first method.

FIG. 2 is a control pattern diagram of a second method.

[Explanation of symbols]

D: Difference between initial adsorption weight (adsorption weight by maximum magnetic force) and target weight, S: target weight, S _S : reference target weight, V: output voltage, V _H : maximum voltage, W: adsorption weight, W _E ... Initial adsorption weight, W _K … switching weight, ΔW… fall judgment weight.

Claims (3)

[Claims] 1. A method of controlling the magnetic force of a lifting magnet by controlling an output voltage or a current while detecting the weight of the magnetic material to be attracted, thereby adjusting the weight of the magnetic material attracted and supported by the lifting magnet. In this method, a magnetic material with a weight exceeding the target weight is attracted and suspended by a lifting magnet with the maximum magnetic force, and the magnetic force is reduced steeply while the weight of the magnetic material is rapidly dropped and reduced. After the adsorption weight reaches a predetermined switching weight exceeding the target weight, the magnetic force is gradually decreased to gradually drop the magnetic material, and when the adsorption weight of the magnetic material reaches the target weight. A method for adjusting the weight of the attracted magnet by the lifting magnet, wherein the method is to restore the maximum magnetic force. 2. The method of controlling the magnetic force of the lifting magnet by controlling the output voltage or the current while detecting the weight of the magnetic material to be attracted, thereby adjusting the weight of the magnetic material attracted and supported by the lifting magnet. A method in which a magnetic material having a weight exceeding a target weight is attracted and suspended by a lifting magnet having a maximum magnetic force, and the magnetic force is reduced at a steep gradient until the magnetic material starts to fall from the lifting magnet. After the start of dropping of the magnetic material is grasped from the change in the weight of the magnetic material, the magnetic force is gradually decreased to gradually drop the magnetic material, and when the weight of the magnetic material reaches the target weight. A method of adjusting the weight of the attracted magnet by the lifting magnet, wherein the method is to restore the maximum magnetic force. 3. A method of controlling the magnetic force of the lifting magnet by controlling an output voltage or a current while detecting the weight of the magnetic material to be attracted, thereby adjusting the weight of the magnetic material attracted and supported by the lifting magnet. A method wherein a magnetic material having a weight exceeding a target weight is attracted and suspended by a lifting magnet having a maximum magnetic force, and a difference between an actual adsorption weight and a target weight by the maximum magnetic force exceeds a predetermined selection reference value. In this case, while the magnetic force is reduced in a steep gradient, the magnetic material adsorption weight is rapidly dropped and reduced, and after the adsorption weight reaches a predetermined switching weight exceeding the target weight, the magnetic material is gradually reduced. The magnetic force is reduced at a gentle gradient so that the magnetic material is dropped, and when the magnetic material adsorption weight reaches the target weight, the magnetic material is returned to the maximum magnetic force. If the difference between the actual adsorbed weight and the target weight is equal to or less than the selection reference value, the magnetic force is decreased at a steep gradient until the magnetic material starts to fall from the lifting magnet, and the magnetic material is decreased. After the start of falling of the magnetic material is grasped by the change in the adsorption weight, the magnetic force is gradually decreased to gradually drop the magnetic material, and when the magnetic material adsorption weight reaches the target weight, the maximum magnetic force is reduced. A method for adjusting the weight of suction by a lifting magnet, wherein the weight is adjusted to return.