JPH0714792B2 - Steel plate hanging number selection control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling the number of suspended steel plates, and more particularly to a method for controlling the suspended steel plate number when suspending a specified number of steel plates on an overhead crane equipped with a lifting magnet.

[Prior Art] Overhead cranes equipped with lifting magnets are widely used for transporting steel sheets. The lifting magnet refers to a lifting device for a crane that includes one or more electromagnets. In an overhead crane for transporting steel plates, one or a plurality of lifting magnets are suspended by a lifting beam that is wound by a trolley via a chain.

When conveying steel sheets, it may be necessary to lift a specified number of steel sheets from the stacked steel sheets. In such cases,
Adjust the exciting current of the lifting magnet so that the magnetic attraction force acting between the lower surface of the lifting material and the upper surface of the non-lifting material is smaller than the weight of the non-lifting material, Separated. For example, in order to separate only the hoisting material from the non-hoisting material, first, the lifting magnet to be used is selected according to the length of the hoisting material. Next, the lifting magnet pitch is calculated from the size of the lifting material, etc., and the lifting share weight added to each lifting magnet is calculated. Then, in consideration of the shared weight and the deflection of the steel plate at the time of lifting, the exciting current of each selected lifting magnet is set according to the total thickness of the lifting material and the steel type.

As another method for selecting the number of suspended steel plates, there is a method disclosed in Japanese Patent Laid-Open No. 154767/50. In this method, the magnetic poles in the lifting magnet are arranged alternately in N poles and S poles or in a staggered manner, and it is possible to select N poles and S poles in a wide range according to the size and number of lifting materials. . As another method, there is a method disclosed in Japanese Utility Model Publication No. 53-105279.
According to this method, a suction attachment having a recess is formed on the steel plate suction surface of each magnetic pole in the lifting magnet, thereby enabling a wide control of the penetration density and depth of the magnetic flux into the steel plate.

[Problems to be Solved by the Invention] As shown in FIG. 3, a combination of two steel plates having different sizes,
For example, it is assumed that the upper steel plate is a wide thin material and the lower steel plate is a thin narrow material having a relatively small unit weight, and the number of sheets is selected. In this case, the width of the lifting magnet is narrower than the width of the upper steel plate. Therefore, if the steel plate is to be lifted, the steel plate bends due to the woofer hang in the width direction. as a result,
An air gap is created between the steel plate and the lifting magnet, which may cause a falling plate. The air gap disappears if the exciting current of the lifting magnet is increased,
Due to the excessive suction force, the lower steel plate is sucked and the number of sheets cannot be selected.

FIG. 4 shows the above-mentioned Japanese Unexamined Patent Application Publication No.
5 shows the total suspended plate thickness and exciting current characteristics of the lifting magnets disclosed in No. 50-154767 and No. 53-105279. In these methods, the suspended sheet sorting property was improved to some extent, but in the figure, the minimum current at which the upper steel plate was hung was I _min , and the maximum current at which the lower steel plate was not absorbed was I _min .
_{If max} is set, as can be seen from the figure, the smaller the lifting plate thickness, the narrower the selectable excitation current width (I _max −I _min ) becomes, that is, the selection becomes difficult, and it is not always possible to select a predetermined number of sheets. Not necessarily. If you try to solve it,
A bar called a dunnage should be laid in the width and length directions of the steel plate so that the deflection of the steel plate is reduced, or the size of the steel plate should be aggregated to limit the difference between the width and length of the steel plate. The former method requires manual labor for crane work, significantly lowering the crane work rate and deteriorating logistics in the factory. But it is not perfect. In addition, the latter method has the disadvantage that the number of ridges inevitably increases due to the restriction of the steel plate size, reducing the area efficiency in the warehouse and increasing the crane operating rate. It is not always optimal in the actual operation of.

Therefore, the present invention is intended to provide a steel plate suspension number selection control method capable of reliably hoisting a specified number of steel plates even with a combination of steel plates of different sizes.

[Means for Solving the Problem] The method for controlling the number of hanging steel plates according to the present invention sets the exciting current of the lifting magnet in advance according to the number of hoists, and attracts the specified number of steel plates from the stacked steel plates by the lifting magnet. In the hoisting method, the exciting current for hoisting the specified number or less than the specified number of steel plates is set in advance, the lifting magnet excited by the exciting current is brought closer to the hoisting steel plate, and the lifting magnet is held near the steel plate, and at least the lifting magnet is The exciting current is gradually increased until the steel plate is attracted.

In setting the excitation current, when less than the specified number of steel plates are hoisted, the number of small steel plates is about 1 to 2. The distance when the lifting magnet is brought closer to the steel plate to be lifted and held depends on the number of lifting magnets used, the pitch between lifting magnets, the size, weight, material of the lifting material, the number of lifting materials and other lifting conditions. It is between about 200 mm and not touching the steel plate, preferably about 50 to 100 mm. From the standpoints of reliable separation of hoisting material and non-hoisting material, performance of the hoisting device, work efficiency, etc., it is desirable to adsorb the steel plate within 10 _S, for example, from the start of the current increase, or the rate of increase of the exciting current from 1 to 1 A It is appropriate to set about / S. The upper limit of the excitation current increase is the current value at which the non-lifting material is not lifted. The optimum values such as the distance, the current increasing speed, the adsorption time, etc. are obtained in advance for the actual machine, and are stored as a calculation table in the control computer together with the lifting conditions.

[Operation] In the present invention, the lifting magnet excited by a specified number or less than the specified number of steel plates is lifted, that is, a lifting magnet that is excited by a small excitation current is brought close to the lifting steel plate, and the distance between the lifting magnet and the steel plate is reduced to some extent. Hold the lifting magnet. At that position, the lifting magnet has not yet attracted the target steel plate. Then, the exciting current is gradually increased until the lifting magnet attracts the steel plate. The adsorption of the steel sheet can be detected while gradually increasing the exciting current. Further, by detecting the steel plate adsorption, the exciting current for the steel plate adsorption can be determined. Therefore, the exciting current can be supplied to the lifting magnet without excess or deficiency, and the specified number of steel plates can be reliably lifted.

[Embodiment] In the steel plate carrying ceiling crane used in this embodiment, five lifting magnets are arranged on the elevating beam along the elevating beam. Each lifting magnet has three electromagnets. In addition, in this embodiment, an example will be described in which the exciting current is increased depending on the portion (center portion and end portion) of the lifting magnet and the ground cutting order.

FIG. 1 is a block diagram showing an example of a control device for carrying out the method for controlling the number of suspended steel plates according to the present invention, and FIG. 2 is a diagram showing an example of a change in exciting current when a steel plate is attracted.

First, the lifting magnet 11 in the host computer 1 is based on the size of the steel plate, the number of hangings, and the stacking order.
The number of used magnets (only one is shown in FIG. 1) and the beam pitch (interval between adjacent lifting magnets) are obtained, and the result is used as the lifting magnet selection signal S _{Ln to} determine the lifting magnet lifting portion determination circuit 3 and the exciting current. It is output to the arithmetic circuit 2. Further, the host computer 1 uses the standard excitation current I _on for each lifting magnet 11 and the correction current set values I _ca and I _cb due to the deflection of the steel plate, etc. based _on the size of the steel plate, the number of hanging magnets, the number of lifting magnets used and the beam pitch. Ask for. The obtained reference excitation current I _on is the excitation current calculation circuit 2
In addition, the correction current setting values I _ca and I _cb are calculated by the correction current calculation circuits 4, 5, and
Output to 6 respectively. In the exciting current calculation circuit 2, when the # 1 lifting magnet is used as a representative, for example, the initial setting exciting current _{Io (1)} is obtained from the reference exciting current I _o1 from the _host computer 1 and the lifting magnet selection signal S _Ln . Then, the initial setting excitation current I _{o (1)}
Is the initial current set value I for adsorption control via the adsorption control circuit 18.
_It is set in the set current selection circuit 8 as _a1 . Furthermore, the _host computer 1 uses the suspension failure determination circuit 17 for the planned lifting weight W _PLMID , the maximum value W _PLmax and the minimum value W _{PLmin thereof,} and the planned _suspension thickness T _PLMID , the maximum value T _PLmax and the minimum value T _{PLmin thereof.} Is output.

Next, when the hoisting beam is lowered from the trolley of the overhead crane and landed on the uppermost steel plate on which the lifting magnets 11 are stacked, the initial setting exciting current I _{o (n)} is output from the exciting current calculating circuit 2 to the setting current selecting circuit 8 Also, it is supplied as an exciting current I _LM1 to the coil of the electromagnet of the lifting magnet 11 via the exciting current control device 9. When all the lifting magnets 11 are energized, winding is started.
The winding control device 10 receives the signal P _SL from the set current selection circuit 8.
And the winding motor 30 is controlled by the signal P _SM from the winding position sensor 22.

During the winding process, the grounding sensor 12 separates the lifting material from the non-lifting material, that is, the grounding material is lifted.
Detect every 11th. The signal S ₁₁ from the ground cutting sensor 12 is the exciting current calculation circuit 2 and the setting current calculation timing circuit 7
And the cut order determining circuit 14. The set current calculation timing circuit 7 to which the ground cutting signal S ₁₁ is input together with the signal P _SM from the winding position sensor 22 outputs the current correction start timing signal S _Gf to the excitation current calculation circuit 2. The excitation current calculation circuit 2 uses the current correction start timing signal S _Gf
Is input, the deflection current correction value I _ca1 from the deflection correction current calculation circuit 4 and the site correction current value I _cb1 from the lifting magnet site correction current calculation circuit 5 are _added to the initial setting excitation current I _{o (1). -1} and the signal I _cb1-2 from the correction current calculation circuit 6 according to the ground cutting order are added, and the initial setting excitation current I _{o (1)}
To correct. The correction for each part is to make the exciting current of the lifting magnet located at the center of the lifting beam larger than that of the lifting magnets located at both ends. In addition, the correction according to the ground cutting order is to increase the exciting current in the lifting magnet that cuts quickly.

These correction currents are supplied from the exciting current calculation circuit 2 to the set current selecting circuit 8 as a lifting magnet suspension selection current I _OR1 , and further supplied to the coil of the electromagnet of the lifting magnet 11 via the exciting current control device 9. Then, the steel plate is held until it is completely lifted. After the complete lifting, the exciting current during transportation is increased to attract the steel sheet more strongly and the steel sheet is transported to a predetermined position.

In the above winding process, each lifting magnet 11
The magnetic flux sensor 13 detects the magnetic flux passing through the steel plate from the electromagnet, and the detected magnetic flux S ₂₁ is input to the suspension failure determination circuit 17 through the magnetic flux-plate thickness conversion circuit 15. If a falling plate occurs during lifting or if the number of hangings is large, the lifting load sensor 16 and the hanging failure determination circuit 17 detect this. On the basis of this detection result, in the case of a falling plate, the lifting is performed again by a signal from the retry control circuit 19. If the number of hangings is large, the suspension failure determination circuit
Based on the signals from 17 and the falling plate / suction detection circuit 20,
A signal from the separation / adsorption control circuit 18 separates the extra steel plate.

When the number of hanging pieces is small, the lifting beam is lowered again, and the separation / suction control circuit 18 is activated by the suction control selection signal P ₁ and the suction control designation signal S _Ga . When the lifting magnet 11 approaches the uppermost steel plate of the stacked steel plates, the initial current set value I _a1 is applied to the coil of the electromagnet of the lifting magnet 11 from the set current selection circuit 8 through the exciting current control device 9 to the lifting magnet exciting current I _R1.
Supplied as. When the lifting magnet 11 further approaches the steel plate and reaches a predetermined distance, the lifting magnet 11 stops descending and the exciting current is gradually increased at a constant increasing speed as shown in FIG. When the steel plate is attracted to the lifting magnet 11 and the lifting load of the lifting magnet 11 changes, the falling plate / adsorption detection circuit 20 detects this,
The increase of the exciting current is stopped by the obtained adsorption detection signal S _Gc . Then, the exciting current of the lifting magnet 11 is held at the current value I _{RE (n)} at that time. In FIG. 2, a period R _ON shows a period in which the exciting current is increased to the maximum value, and a period T _ON shows a period in which the adsorption control is further executed after the period R _ON . Then, when all the lifting magnets 11 attract the steel sheet, the winding operation is started again.

In the above embodiment, when the number of hoisting pieces is small in the winding process, a control method of gradually increasing the exciting current is carried out.
This method may be adopted from the beginning. In this case, the instantaneous current correction and the deflection correction at the time of ground cutting are unnecessary.

Here, an example in which a specified number of steel plates are lifted by the above device will be described.

Table 1 shows the results of hanging one sheet, comparing the present invention example and the conventional example.

In Table 1, the upper row of the size combinations shows the hoisting material and the lower row shows the non-hoisting material. In the test (a), the thick and wide materials are suspended, and in the test (b), the light and non-lifting material is placed under the thin and wide lifting material.

As is clear from Table 1, in the test (a), the conventional example shows superior results to the inventive example. However, this is because there is a large current difference between the minimum current value I _min (current value required to lift only the first steel plate) and the maximum current value I _max (current value that also lifts the second steel plate). This is because the time required to lift only the first steel plate is too long in the example of the present invention. Conversely, in test (b), the minimum current value
Because the suspension current range of I _min and the maximum current value I _max is small, it is not possible to suspend by one lifting operation in the conventional example. However, in the example of the present invention, the suspension required time was short and the suspension was easy. In this test, the target upper limit current when increasing the current from the initial current is the rated current maximum value 32A of the lifting magnet 11, and the close distance between the lifting magnet 11 and the steel plate is set to 100 mm. By changing the target upper limit current value and the shortest distance according to the size of, it is possible to further shorten the required time for the suspension.

The present invention is not limited to the above-described embodiment. For example, although the exciting current is increased linearly, it may be increased in a curve. Further, the correction of the exciting current due to deflection or the like may be omitted.

[Advantages of the Invention] (1) When there is a thin material or a narrow material with a relatively small unit weight under a thin material or a wide material, the current setting region is narrow and it is extremely difficult to suspend. And the selection area was expanded.

(2) The work time for suspending steel plates was shortened, the work efficiency of the crane was improved, and the efficiency of physical distribution in the factory was able to be achieved.

(3) Warehouse area efficiency has been improved by relaxing size restrictions.

(4) It became possible to automate the number of suspended steel plates.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a control device for carrying out the method for controlling the number of suspended steel plates according to the present invention, FIG. 2 is a diagram showing an example of changes in exciting current when a steel plate is attracted, and FIG. Of the different lifting steel plates, and FIG. 4 are diagrams showing the relationship between the lifting total plate thickness and the exciting current in the conventional lifting magnet. 1 ... Higher-order integrated control device, 2 ... Exciting current calculation circuit, 3
...... Lifting magnet hanging part discrimination circuit, 4 ……
Deflection correction current calculation circuit, 5 ... Lifting magnet part-specific correction current calculation circuit, 6 ... Lifting magnet ground cutting order-specific correction current calculation circuit, 7 ... Set current calculation timing detection circuit, 8 ... Set current selection circuit, 9 ……
Excitation current selection circuit, 10 ...... Winding control device, 11 ...... Lifting magnet, 12 ...... Ground cutting sensor, 13 ...... Flux sensor, 14 ...... Lifting magnet Ground cutting order discrimination circuit, 15 ...... Flux-plate thickness conversion Circuit, 16 ... Lifting load sensor, 17 ... Suspension failure judgment circuit, 18 ... Separation / adsorption control circuit, 19 ... Retry control circuit, 20 ... Falling plate / adsorption detection circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichiro Tanaka 1st Nishinosu, Oita-shi, Oita Pref. Nippon Steel Co., Ltd. Oita Works (72) Inventor Takekichi Yoshida 1st Nishinosu, Oita-shi, Oita Pref. Inside the Oita Steel Works, Ltd. (72) Inventor Kouji Etsujiro Osamu, Oita City, Oita Prefecture, No. 1 Nishinosu Shin-Nippon Steel Co., Ltd. Oita Works (56) References JP-A-50-154767 (JP, A) Actual Kai 57-30242 (JP, U) Actual Kai 53-105279 (JP, U)

Claims (1)

[Claims] 1. A method in which an exciting current of a lifting magnet is set in advance according to the number of hoists, and a specified number of steel plates are adsorbed by the lifting magnet from the stacked steel plates and hoisted. The current is set in advance, the lifting magnet excited by the exciting current is brought close to a steel plate to be lifted, the lifting magnet is held near the steel plate, and the exciting current is gradually increased at least until the lifting magnet attracts the steel plate. Method for controlling the number of suspended steel plates.