JPH0759468B2 - 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 lifting a specified number of steel plates by 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, the exciting currents of the selected lifting magnets are set according to the total thickness of the hoisting material and the steel type.

As another method for selecting the number of suspended steel plates, there is a method disclosed in Japanese Patent Application Laid-Open No. 50-154767. 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. . Further, as another method, there is a method disclosed in Japanese Utility Model Application Laid-Open 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] However, even if the exciting current is set as described above, the lifting conditions are variously changed, so it is difficult to automatically and accurately lift the specified number of steel plates. For example, when the length or width of the lifted steel plate is larger than that of the attraction surface of the lifting magnet, the free end of the steel plate protruding from the lifting magnet is bent by its own weight. In such a case, a gap is created between the steel plate and the attraction surface of the lifting magnet, the attraction force of the lifting magnet on the steel plate is significantly weakened, and it becomes difficult to select a predetermined number of hanging pieces. Further, for a steel plate having a width smaller than the suction surface width of the lifting magnet, the suction force generated on the suction surface is significantly different from the characteristics of the wide steel plate. Therefore, when a plurality of steel plates including steel plates having a width narrower than the attracting surface width of the lifting magnet is hoisted, whether or not the steel sheets are hoisted depends on the stacking position of the narrow steel plates. further,
In a crane with multiple lifting magnets arranged, the lifting material separates from the non-lifting material, depending on the height of the ground or the level of the lifting magnets, the unevenness of the steel plate, etc. It is normal. In such a case, the lifting magnet that has been cut into the ground must bear the lifting weight of the lifting magnet that is not cut into the ground, and an excessive load is applied to the lifting magnet that is cut into the ground. As a result, the steel plate is detached from the lifting magnet and falls, and the specified number of steel plates cannot be lifted.

In order to solve the above problem, a method of changing the arrangement of a large number of magnetic poles and the flow of exciting current, or a modification of the attachment of the attracting surface has been proposed as described above, and the hanging sheet selectivity has been improved accordingly. However, even with these conventional techniques, it is not possible to reliably suspend the specified number of steel plates due to the variety of lifting conditions. For this reason, the crane operator adjusts the exciting current of the lifting magnet while watching the suspended state of the steel plates, and lifts the specified number of steel plates by trial and error. As a result, the work time for suspending steel plates is increased, the work efficiency of the crane is reduced, and it is not possible to automate the selection of the number of suspended steel plates.

Therefore, the present invention is intended to provide a steel plate suspension number selection control method capable of coping with various suspension conditions and capable of reliably suspending a specified number of steel plates.

[Means for Solving the Problems] The method for controlling the number of suspended steel plates according to the present invention is the size and number of suspended steel plates, the number of lifting magnets used,
Also, an exciting current for lifting a specified number of steel plates based on the spacing between adjacent lifting magnets is preset for each lifting magnet, and a specified number of steel plates are attracted from the stacked steel plates by a lifting magnet to be lifted. It includes the steps of a) correction of the set exciting current, (b) increase of the exciting current at the time of ground cutting, and (c) adjustment of the number of hoists.

(B) Calculate the free end deflection of the steel plate longitudinal direction end and the free end deflection of the steel plate width direction end, and calculate the current correction amount in advance from the deflection amount, and the attracting surface width of the lifting magnet in the lifting steel plate. When a narrower steel plate is included, a current correction amount is obtained in advance by the vertical position and plate width of the narrow steel plate in the lifted steel plate, and the preset excitation current is corrected by these correction amounts. When the steel plate is sucked and lifting is performed, the lifting magnet and the non-lifting material are detected separately for each lifting magnet.
The exciting current should be increased immediately after the lifting material and the non-lifting material are separated for each lifting magnet. (C) When the number of lifted steel plates is more than the specified number, the magnetic flux density of the attracting surface is different for each lifting magnet. Smoothly, the exciting current of the lifting magnet is increased at the moment when the falling plate is detected.If the number of suspended steel plates is less than the specified number, hold the lifting magnet near the steel plates and gradually increase the exciting current. After sucking a specified number of steel plates by suction or by lifting the lifted steel plates on the floor and separating the lifting magnet from the steel plates,
Perform hoisting again with an exciting current larger than the previously set exciting current.

In the correction of the above set excitation current, when calculating the free end deflection amount at the longitudinal end of the steel sheet and the free end deflection amount at the width direction end, the deflection amount at the free end is for the bottom steel plate of the hoisting material. Ask. The amount of deflection is the pitch between the lifting magnets, the amount of overhang and the thickness of the steel plate,
It is determined by the elastic deflection formula based on the longitudinal coefficient and the specific gravity or experimentally on the actual machine. The set excitation current is corrected so that the gap between the lifting magnet and the steel plate caused by the free end deflection becomes substantially zero. The corrected exciting current does not necessarily have to make the gap due to the deflection zero. That is, even if there is a slight gap, it is sufficient that the current is large enough to lift the specified number of steel plates.

Further, in the above-mentioned excitation current correction, when a plurality of stacked steel plates including steel plates having a width narrower than the attracting surface width of the lifting magnet is hoisted, a correction coefficient is obtained in advance using the plate width of the narrow steel plate and its position as parameters. . The width smaller than the attraction surface width of the lifting magnet means that it is about 1 to 50% smaller than the attraction area of the lifting magnet, although it depends on the lifting conditions. In addition, in a state in which a plurality of steel plates including narrow steel plates are stacked, the narrow steel plate is located at the top, the pattern located at the bottom, the pattern located in the middle, and all the narrow steel plates. It is also possible to divide the pattern into four patterns, the correction coefficient is obtained for each of these patterns, and the exciting current is corrected according to the pattern.

When separating the hoisting material from the non-hoisting material, that is, when increasing the exciting current when cutting the ground, the rate of increase with respect to the set exciting current is the number of lifting magnets used, the pitch between lifting magnets, the size, weight, material of the lifting material, and the number of hoisting materials. Depending on other lifting conditions, for example 1.
It is about 1 to 2.0 times. Further, the time from when the ground is cut to when the exciting current is increased varies depending on the lifting condition, but is, for example, about 0.1 to 0.5 seconds. This delay time is the time for confirming the ground cutting. To detect the ground cutting, for example, a change in the load acting on the chain that suspends the lifting magnet is detected. In order to detect this load change, a combination of a spring and a switch arranged between the lifting beam and the lifting magnet, a load cell, or the like is used. Further, the rate of increase of the exciting current of the lifting magnets arranged in the central portion may be made larger than the exciting current of the lifting magnets arranged at both ends. Furthermore, the increasing rate of the exciting current may be increased as the lifting magnet cuts the ground faster.

Further, in adjusting the number of hoisted sheets, when more than the specified number of steel sheets are hoisted, it is desirable to drop the steel sheets within, for example, 10 seconds from the start of gradually decreasing the magnetic flux density. The increase of the exciting current is, for example, about 10 A, which is the same as when the ground is cut. When the number of sheets is less than the specified number, the holding distance between the lifting magnet and the steel plate varies depending on the lifting conditions, but is between 200 mm and 200 mm, preferably 50-100 mm, so that the lifting magnet does not contact the steel plate. When the steel plate is landed and lifted again, the lifting magnet is excited with an exciting current that is, for example, about 1.2 times the previously set exciting current. Further, it is desirable to adsorb the steel plate within, for example, 10 seconds after the start of increasing the exciting current. The falling of the steel plate and the attraction of the steel plate are detected by using a load meter or the like attached to each lifting magnet. The magnetic flux density is detected using a Hall element.

In the above steps, proper values such as the amount of deflection, the current correction due to the position of the narrow steel plate, the increase of the exciting current at the time of ground cutting or the adjustment of the number of hoisting, or the gradual decrease of the magnetic flux density are experimentally obtained in advance using an actual machine. The calculation table is stored in the control computer together with the lifting conditions.

[Operation] Since the exciting current of the lifting magnet is determined in consideration of the bending of the hoisted steel plate due to its own weight, and the width and position of the narrow steel plate, it is possible to obtain the exciting current for accurately suspending the specified number of sheets. . Further, in the process of sucking and lifting the steel sheet, the exciting current is increased immediately after the ground cutting, so that the lifting material is more strongly and reliably attracted by the lifting magnet. Since the exciting current increases immediately after the ground cutting, the non-lifting material is not lifted. Further, immediately after the lifting, the excess or deficiency of the lifted steel plates is detected and the number of lifted steel plates is adjusted, so that the specified number of steel plates can be lifted more reliably.

[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 is equipped with 3 × 6 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.

FIGS. 1 to 3 show an example of the present invention. FIG. 1 is a flow chart showing a procedure for setting an exciting current, FIG. 2 is a flow chart showing a procedure for controlling the number of sheets when a steel plate is lifted, and a third step. The figure is a block diagram of a control device for carrying out the method for controlling the number of suspended steel plates.

First, the size of the steel plate (plate thickness,
(Width and length), the number of lifting magnets 11 used (only one is shown in FIG. 3) and the beam pitch (distance between adjacent lifting magnets) are calculated based on the number of suspended magnets and the stacking order. The lifting magnet selection signal S _Ln is output to the lifting magnet lifting portion determination circuit 3 and the exciting current calculation circuit 2. In addition, the host computer 1 uses the lifting magnet 11 based on the size of the steel plate, the number of hangings, the number of lifting magnets 11 used, and the beam pitch.
The reference excitation current I _On , the deflection correction current set value I _ca, and the lifting correction current set value I _cb are _calculated for each. The obtained reference excitation current I _On is supplied to the excitation current calculation circuit 2, the deflection correction current set value I _ca is provided to the deflection correction current calculation circuit 4, and the lifting correction current set value I _cb is provided to the lifting magnet portion correction current calculation circuit 5 and the ground. It is output to the correction current calculation circuit 6 for each cutting order.

When the lifting material includes a steel plate having a width narrower than the attracting surface width of the lifting magnet 11, the reference excitation current I _On is taken into consideration in consideration of the width of the narrow steel plate and its vertical position.
Ask for. FIG. 4 shows a pattern in which the stacked states of the lifting materials including the narrow steel plates are roughly classified. In FIG.
Pattern (a) is a pattern in which a narrow steel plate is located in the middle, pattern (b) is a pattern located in the uppermost part, pattern (c) is a pattern located in the lowermost part, and pattern (d) is all in the width. It is a narrow steel plate pattern. Fifth
The figure shows an example of the correction coefficient. A correction coefficient is calculated according to these patterns and plate widths, and the reference excitation current I _On
Is multiplied by this correction coefficient to obtain the corrected exciting current.

The amount of deflection when obtaining the deflection correction current value is obtained as follows.

The amount of deflection is calculated separately for the amount of deflection in the plate width direction and the amount of deflection in the length direction, as a beam in which the overhang portion of the steel plate receives an evenly distributed load over the entire length.

The amount of deflection in the width direction and the amount of deflection in the length direction are obtained by the following equations (1) and (2), respectively.

(3 × OH _W ⁴ × H × γ) / (2 × E × h ³ ) + ΣT _n-1 + (5 × OH _p ⁴ × H × γ) / (32 × E × h ³ ) …… (1) (3 × OH _L ⁴ × H × γ) / (2 × E × h ³ ) + ΣT _n-1 + (3 × OH _W ⁴ × H × γ) / (2 × E × h) (2) Here , OH _W : Overhang in width direction (mm) OH _L : Overhang in length direction (mm) OH _p : Distance between pitches (mm) H: Thickness of uniform load term (mm) h: Second moment of end face Thickness of the bottom steel plate (mm) E: Longitudinal elastic modulus: 21000 (kgf / mm ² ) γ: Specific gravity: 7.85 × 10 ^-6 (kgf / _mm3 ) ΣT _{n- 1} : Total thickness of steel plates above the bottom steel plate.

When the deflection amounts in the width direction and the length direction of the steel sheet are obtained, the correction current to be added to the reference excitation current is obtained using the calculation table stored in the host computer 1.

In the exciting current calculation circuit 2, for example, when the # 1 lifting magnet is used as a representative, the reference exciting current I _O1 and the lifting magnet selection signal S _Ln from the _host computer 1 are used to initialize the exciting current I _{O (1 )} Is required.

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 _PLmax.
W _PLmin , and plate thickness to be _hoisted T _PLMID , maximum value
_Outputs T _PLmax and minimum value T _PLmin .

Next, when the lifting beam is lowered from the trolley of the overhead crane and the lifting magnet 11 is landed on the uppermost steel plate of the stacked steel plates, the initial setting exciting current I _{O (1)} is set by the exciting current calculating circuit 2 to the set current. The lifting magnet exciting current I _LM1 is supplied to the coil of the electromagnet of the lifting magnet 11 via the selection circuit 8 and the exciting current controller 9.

The landing of the lifting magnet 11 with the steel plate is detected by the landing / ground cutting sensor 12 for each lifting magnet 11. The landing / ground cutting sensor 12 is composed of a combination of a spring and a limit switch provided in a chain that suspends the lifting magnet 11, and detects landing and ground cutting from a change in load applied to the chain. After all the lifting magnets 11 have landed and are excited, winding is started. The winding control device 10 controls the winding motor 30 by the signal P _SL from the set current selection circuit 8 and the signal P _SM from the winding position sensor 22.

In the winding process, the landing / ground cutting sensor 12 detects ground cutting for each lifting magnet 11. The signal S ₁₁ from the landing / ground cutting sensor 12 is the exciting current calculation circuit 2,
Setting current calculation timing circuit 7 and ground cutting order determination circuit
Entered in 14. The ground cutting order discrimination circuit 14 discriminates the lifting magnet 11 that cuts quickly, and the discrimination signal S _1n is input to the ground cutting sequence-specific correction current calculation circuit 6. The correction current calculation circuit 6 for each ground cutting order calculates the correction current of the exciting current according to the ground cutting order. The set current calculation timing circuit 7 to which the ground cutting signal S ₁₁ is input together with the signal from the winding position sensor 22 is used to set the current correction start timing signal S _Gf to the excitation current calculation circuit after the delay time T _LM shown in FIG. 6 has elapsed. Output to 2. When the current correction start timing signal S _Gf is input, the excitation current calculation circuit 2 obtains the ground-cutting correction current I _ho by subtracting the initial setting excitation current I _{O (1)} from the maximum excitation current.
Here, the maximum exciting current refers to the exciting current required to lift the hoisting material to which one uppermost non-hoisting material is added. Furthermore, expression the earth cutting correction current Ih _o based on the signal I _CB1-2 from site specific correction current value I _CB1-1 and land cutting forward specific correction current calculating circuit 6 from the lifting magnet site specific correction current calculation circuit 5 The transient correction current Ih ₁ is calculated by the correction in (3).

_{Ih 1 = Ih o × k 1} × k 2 × k h ...... (3) here, k _1: lifting magnet site-specific correction coefficient k _2: earth cut order-wise correction coefficient k _h: an overshoot coefficient. In the lifting magnet 11, the exciting current rises quickly, but the magnetic flux density rises slowly. The overshoot coefficient is for compensating for the delay in the magnetization of the electromagnet.

After the transient correction current Ih ₁ is held for Thd time, it is switched to the steady correction current Ih ₂ given by the equation (4).

_{Ih 2 = Ih o × k 1} × k 2 ...... (4) constant correction current Ih ₂ is a steel sheet as shown in FIG. 6 is held until lifted completely. 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. These transient correction current Ih ₁ and steady-state correction current Ih ₂ are supplied as the lifting magnet suspension selection current I _OR1 from the excitation current calculation circuit 2 to the set current selection circuit 8 and further through the excitation current control device 9 to the lifting magnet 11. Supplied to the coil of the electromagnet.

In addition, the correction of the exciting current due to the bending of the hoisted steel plate is performed by the bending correction current value from the bending correction current calculation circuit 4.
By I _ca1 , it is performed at the same time as the correction by the above ground cutting.

In the process of lifting, the weight of the steel plate being lifted is measured by the lifting load sensor 16. The signal is input to the suspension failure determination circuit 17, and it is determined here whether or not the specified number of steel plates are suspended. Further, the magnetic flux sensor 13 detects the magnetic flux passing through the steel plate by the magnetic flux sensor 13 for each lifting magnet 11, and the detected magnetic flux S ₂₁ is input to the suspension failure determination circuit 17 via the magnetic flux-plate thickness conversion circuit 15.

If the number of lifted steel plates is greater than the specified number, signals from the suspension failure determination circuit 17 and falling plate / suction detection circuit 20
Signal P ₁ from disconnection / adsorption control circuit 18 based on S _GC
The extra steel plate is separated by. As for the separation of the steel plates, the magnetic flux density is gradually reduced within _a preset time Ta as shown in FIG. 7, and the excess steel plates are dropped. Then, at the moment when the falling plate is detected, the magnetic flux density B _D at that time is rapidly returned to the magnetic flux density B _O at the time of lifting.

When the number of lifted steel plates is less than the specified number, the suspension failure determination circuit 17 detects that the specified number is small by the signal T _PL1 from the magnetic flux-plate thickness conversion circuit 15. This detection result
S _Gb is output to the retry control circuit 19 and again the lifting magnet is generated by the signal P ₂ from the retry control circuit 19.
11 approaches the uppermost steel plate of the stacked steel plates. And
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 suspension load of the lifting magnet 11 changes, the falling plate / adsorption detection circuit 20 detects this and the increase of the exciting current is stopped by the subsequent adsorption detection signal S _GC . The exciting current of the lifting magnet 11 is the current value at that time.
It is held at I _{RE (n)} and lifting is restarted. In FIG. 8, 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 .

In the above embodiment, an example 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 has been described, but the present invention is not limited to this. For example, a method for controlling the number of suspended steel plates, which lacks either the lifting magnet portion, the increase in the exciting current depending on the ground cutting order, or both, may be used.

[Effects of the Invention] According to the present invention, the exciting current is corrected based on the deflection of the steel sheets and the stacking conditions of the narrow steel sheets, and the exciting current is increased during ground cutting to make the hanging accurate, and further, the hoisting condition The exciting current is adjusted accordingly. As a result, it is possible to sort hanging numbers with high accuracy. As a result,
The work time for suspending steel sheets has been shortened, the work efficiency of the crane has been improved, and the selection of the number of suspended steel sheets has become possible. In addition, the suspended sheet selection area has been expanded.

[Brief description of drawings]

FIG. 1 is a flow chart showing a procedure for setting an exciting current according to the present invention, FIG. 2 is a flow chart showing a procedure for controlling a number of sheets when hoisting steel plates according to the present invention, and FIG. 3 is a method for controlling a number of hanging steel sheets according to the present invention. FIG. 4 is a block diagram showing an example of a control device for implementing the above, FIG. 4 is a drawing showing a stacking pattern of a plurality of steel plates including a narrow steel plate, and FIG. 5 is a line showing an example of a correction coefficient when the narrow steel plate is included. Figures and 6 are time charts for lifting steel plates, Fig. 7 is a time chart for plate separation control when extra steel plates are lifted, and Fig. 8 is a time chart for adsorption control when the number of lifting steel plates is insufficient. is there. 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 ... Landing / ground cutting sensor, 13 ...
… Magnetic flux sensor, 14 …… Lifting magnet Ground cutting order discrimination circuit, 15 …… Flux-plate thickness conversion circuit, 16 …… Lifting load sensor, 17 …… Suspension failure determination circuit, 18 …… Separation / adsorption control circuit, 19 ...... Retry control circuit, 20 …… Falling plate / suction detection circuit.

Front page continuation (72) Inventor Takeda Kokikichi, Oita City, Oita Prefecture, 1st Nishinosu Nippon Steel Co., Ltd. Oita Steel Co., Ltd. Company Oita Works (56) References JP-A-60-232391 (JP, A) JP-A-50-154767 (JP, A) Actual development 63-157080 (JP, U) Actual development 63-157081 ( JP, U) Actual opening Sho 53-105279 (JP, U) Actual opening Sho 57-4052 (JP, Y2)

Claims (1)

[Claims] 1. An exciting current for lifting a specified number of steel plates is preset for each lifting magnet based on the size of the steel plates and the number of lifting magnets, the number of lifting magnets used, and the interval between adjacent lifting magnets. In the method of lifting a specified number of steel plates by attracting them with a lifting magnet, calculate the free end deflection of the steel plate longitudinal direction end and the free end deflection of the steel plate width direction end, and obtain the current correction amount in advance from the deflection amount. In addition, when the steel plate to be lifted includes a steel plate that is narrower than the attracting surface width of the lifting magnet, the current correction amount is obtained in advance by the vertical position and the plate width of the narrow steel plate in the lifting steel plate, and Correct the preset exciting current, attract the steel plate, and lift it. The lifting magnet and the non-lifting material are detected for each lifting magnet, and the exciting current is increased immediately after the lifting material and the non-hanging material are separated for each lifting magnet. When the number of steel plates is more than the specified number, the magnetic flux density on the attracting surface is smoothly reduced for each lifting magnet, the exciting current of the lifting magnet is increased at the moment when the falling plate is detected, and the number of lifted steel plates is the specified number. If less, hold the lifting magnet near the steel plate and gradually increase the exciting current to attract and attract the specified number of steel plates, or place the lifted steel plate on the floor and pull the lifting magnet away from the steel plate, then set the previous setting. The method for controlling the number of suspended steel plates is characterized in that the hoisting is performed again with an exciting current larger than the exciting current.