Magnetic lifter

Abstract

The present invention relates to an optimized structure and a control system of a magnetic lifter. The control system of a magnetic lifter according to an embodiment of the present invention may comprise: a magnetic lifter unit comprising a plurality of ports in the form of an accommodation groove and comprising auxiliary magnetic poles which are accommodated and fixed in the plurality of ports, respectively, operate as a magnetic lifter having N and S poles when external power is applied, to generate an attractive force with respect to an object to be attracted, and prevent magnetic force loss caused by an air gap with a contact surface of the object to be attracted; and a magnetic force control device configured to convert a DC voltage applied to a solenoid coil into an AC voltage and apply the converted voltage, in order to remove residual magnetism of the object to be attracted after the object to be attracted is lowered to a destination.

Description

Magnet lifter

[0001] The present invention relates to an optimized structure and control system for a magnet lifter, and more specifically, to a magnet lifter used, for example in the logistics of steel products, wherein the cross-sectional structure of the lifter is varied to include line contact and point contact in addition to surface contact depending on the surface shape of the adsorbed object, thereby providing effective and optimized magnetic force, and wherein the magnetic flux density at the pole surface is uniformized and formed close to the saturation value in the natural characteristics of the magnet while following natural phenomena throughout all processes from magnetization, which is the generation of magnetic force, to demagnetization after use.

[0002] Generally, magnetic lifters are essential equipment for steel mill operations, moving steel plates and heavy steel materials produced while installed on cranes. At this time, the suction force of the magnetic lifter is basically determined by the load of the object to be lifted, but in the case of lifters for steel plates, conditions based on the width and length must be added in addition to the load. In particular, as the width and length of steel plates have increased to approximately 5.5m and 23m respectively due to the development of steelmaking technology, magnetic lifters for lifting them can accommodate the increase in steel plate width by connecting multiple magnetic lifter units to form a combined magnetic lifter assembly called a Pot, and can also accommodate the increase in steel plate length by arranging multiple combined magnetic lifter assemblies at regular intervals.

[0003] Since the Pot-type magnet lifter assembly is structured to mechanically connect multiple magnet lifter units, the suction force and self-weight increase as the number of magnet lifter units increases. Furthermore, as multiple such assembly units are arranged, the actual lifting capacity of the crane decreases by the amount of the increased self-weight. In addition, the sum of the total suction forces of the aforementioned assembly units exceeds the crane's lifting capacity by several times; this far surpasses the safety standards set by relevant regulations, thereby posing an economic burden in terms of energy consumption and other factors.

[0004] In other words, conventional magnet lifters are critical equipment for transporting heavy steel products in steel mills and shipyards. To improve logistics productivity from steel production to shipment, it is necessary to lift larger quantities at once; this presents a problem that requires stronger cranes and reinforced building structures to support them. This constitutes an economic burden.

[0005] In addition, in the case of a shipping yard, multiple steel plates are lifted each time, and the magnetic lifter requires a strong suction force regardless of the safety standards required according to the crane's lifting rating. Therefore, magnetic lifters need to be manufactured separately for production processes that lift one plate at a time and for shipping yards that must lift multiple plates, depending on the application.

[0006] In a magnet lifter, current is applied to a winding wound around a magnetic core to generate a magnetizing force (H), and as this magnetizing force passes through the magnetic core, a magnetic force is generated, and one side of the core becomes the N pole and the other side becomes the S pole, and the N pole and the S pole cannot be separated.

[0007] Magnetomotive force can be expressed as in <Relation 1>.

[0008] [Relationship 1]

[0009] Magnetomotive force (H) = N × I

[0010] (Here, N is the number of turns, I is the current)

[0011] When this magnetomotive force penetrates a magnetic core, a magnetic force is generated, and the amount of magnetic flux per unit area of ​​the core is called magnetic flux density. Magnetic flux density is expressed as in <Equation 2>.

[0012] [Relationship 2]

[0013] Magnetic flux density (B) = μ × H

[0014] (Here, μ is the permeability, a magnetic property of the material)

[0015] At this time, the magnitude F of the generated force (adsorption force / magnetic force) is expressed as in <Equation 3>.

[0016] [Relationship 3]

[0017] F = k × B² × S (where S is the cross-sectional area and B is the magnetic flux density)

[0018] At this time, since the magnetomotive force (H) is determined by the current applied to the solenoid winding, the magnitude of the magnetic force (F) can be adjusted by adjusting the applied current or voltage, but it can be adjusted more effectively if the distribution of magnetic flux on the pole surface is uniform.

[0019] Meanwhile, the action of magnetic force must consider line and point contact in addition to surface contact depending on the condition of the iron workpiece. Since magnetic force disperses into the space when the lifter surface comes into contact with the iron workpiece, reducing the lifting force, various contact methods must be used to prevent loss of magnetic force. shows the contact between the lifter surface and the workpiece.

[0020] [Table 1]

[0021]

[0022] The process of magnetic force generation and extinction by electric power is called the hysteresis characteristic, and the air layer between the object to be adsorbed and the lifter surface is called the air gap. The state of decrease according to the size of the magnetic force and the air gap is shown in a graph. This is clearly illustrated in Figure 3. Another natural characteristic of the magnet is that the magnetic force generated in the lifter does not become "zero" even when the applied power is cut off, and a certain amount remains for a certain period of time; this is called residual magnetism. Since repeated use of the magnet lifter for a long period causes disturbances in the magnetic force, residual magnetism must be removed immediately after use.

[0023] [Prior Art Literature]

[0024] [Patent Literature]

[0025] (Patent Document 1) Korean Registered Patent Publication No. 10-1767523 (August 7, 2017)

[0026] (Patent Document 2) Korean Registered Patent Publication No. 10-1358184 (January 27, 2014)

[0027] (Patent Document 3) Korean Registered Patent Publication No. 10-1032723 (April 26, 2011)

[0028] The purpose of the embodiments of the present invention is to provide an optimized structure and control system for a lifter used, for example in the logistics of steel products, which provides effective and optimized magnetic force by varying the cross-sectional structure of the lifter from magnetization (generating magnetic force) to line contact and point contact in addition to surface contact depending on the surface shape of the adsorbed object, and which uniformizes the magnetic flux density at the magnetic pole surface and maintains a higher average magnetic flux density while following natural phenomena throughout all processes, from magnetization to demagnetization after use.

[0029] The steel plate lifter unit currently in use consists of a circular N pole in the center and a square border S pole, and the areas of the N pole and S pole must be the same, but the shape and condition of the magnetic poles are different and the spacing between the N pole and S pole is not constant, so the generation and operation of magnetic force are inefficient (Fig. 7a).

[0030] In addition, in a steel plate assembly called a Pot that uses multiple magnet lifter units connected together, the magnetic force is lost as the edges between adjacent individual magnet lifters are shared, resulting in significant waste of power and magnetic force (Fig. 7b).

[0031] As a result of actual measurement, the suction power of the Pot, which is connected with 6 magnet lifter units having a suction power of 6 ton, is 24 ton, and 12 ton of suction power has been lost (Fig. 7b).

[0032] Furthermore, in a magnetic lifter for steel plates composed of a circular N pole and a square-bordered S pole, and a magnetic lifter for scrap composed of a circular N pole and a circular-bordered S pole, the cross-sectional areas of the N and S poles are the same or similar, but the average magnetic flux density differs, resulting in an inefficiently low effect when the magnetic force is applied.

[0033] When magnetic force is applied, if the contact between the magnetic pole surface and the object to be adhered is surface-to-surface contact, there is no space; however, if the contact is surface-to-surface or surface-to-point contact, the space is called an air gap. Since magnetic force loss occurs in the air gap, it is over-designed. Consequently, the over-designed magnetic field lines are not sufficiently transmitted to the object to be adhered and diverge into the surrounding space, causing significant adverse effects around the lifter, such as control system malfunctions or collisions.

[0034] Conventional magnetic lifters are composed of magnetic poles made of a single block of steel, and due to their natural characteristics, the magnetic flux density distribution within the poles is "0" (Zero) at the center and is horn-shaped, concentrating to a maximum at angular or sharp edges. Therefore, it is not easy to adjust the magnetic force by changing the applied current or voltage, and thus the control of the number of steel plates lifted and transported to a specific location is unstable.

[0035] In this case, the average magnetic flux density of the pole surface is a constant value between “0” (Zero) and 1.5 Tesla depending on the condition of the pole surface; however, if the pole surface is divided and has long angled edges, the average magnetic flux density will be formed close to the saturation value of 1.5 Tesla.

[0036] In addition, designing a magnet lifter by fixing the magnetic flux density of the pole face to 1.5 Tesla overlooks natural phenomena. While it is argued that improving the magnetic force (i.e., attraction force) of the magnet lifter leads to the enlargement of the lifter, the strengthening of the crane, and the reinforcement of the building structure, according to the formula (or theory), the cross-sectional area of ​​the lifter decreases by 50%, but the magnetic flux density becomes 200%, so the force (F) becomes 200% and the lifter becomes lighter.

[0037] In fact, when measuring the surface magnetic flux density of a magnet lifter, the flux is "0" at the center of the pole face due to natural characteristics and reaches a maximum at the angular or sharp edges of the pole; therefore, in transformers, which share the same engineering theory as magnet lifters, thin sheets of 0.3 mm or less are laminated to maintain the average magnetic flux density within the iron core close to 1.5 Tesla.

[0038] On the other hand, the part in contact with the excitation surface becomes naturally magnetized, but the magnetic flux disappears after a certain period of time.

[0039] At this time, when the magnetic surface and the adsorbed iron product come into contact, if a lifter with enhanced magnetic force is used to compensate for the loss of magnetic force due to the air gap between the magnetic surface and the iron product because the surface is cylindrical or has severe curvature and irregularities, the magnetic force is concentrated on the protruding part of the iron product in contact with the magnetic surface, causing the contact part to become magnetized and the magnetic force to not disappear within a short period of time, resulting in a claim due to the problem occurring during iron processing.

[0040] In addition, when lifting a cylindrical coil, excessive magnetic force is formed to account for the air gap, so thin plates of 1.5 mm or less deform near the line contact area, resulting in a claim.

[0041] In addition, it is thought that changing the polarity of the DC current applied to the magnet lifter after use causes demagnetization, but this is a simple change of polarity and residual magnetism remains, and foreign substances attached to the pole surface due to the remaining residual magnetism leave scratches on the steel plate surface when lifting the steel plate, and this is also a cause of claim.

[0042] The problems of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0043] A magnet lifter and a control system (or driving system) according to an embodiment of the present invention comprises a lifter unit and a port composed of a plurality of lifter units, a lifter unit that includes an auxiliary magnetic field to prevent magnetic loss due to an air gap between the magnetic field surface and the contact surface of the adsorbed object, and an auxiliary magnetic field to provide a grid-shaped angled edge on the magnetic field surface so that the average magnetic flux density on the magnetic field surface of the lifter unit is close to a saturation value of 1 / 5 Tesla, and to remove residual magnetism by applying an AC voltage instead of a DC voltage applied to the solenoid coil to remove residual magnetism between the adsorbed object and the lifter unit after the adsorbed object is lowered to a destination.

[0044] The above magnetic force control device can control the power applied to the solenoid winding so that the magnetic force of the magnet lifter unit is adjusted according to the adjustment of the average magnetic flux density when adsorbing a plurality of steel plates to be adsorbed and sequentially lowering them one by one to a required location.

[0045] The magnet lifter unit may include a winding core configured in a stacked form with a solenoid coil to which the external power is applied, and a magnetic core comprising N-pole and S-pole steel materials formed in a vertical direction connected to each end of the winding core, wherein the N-pole and S-pole steel materials are configured in different layers.

[0046] The steel materials of the N and S poles, respectively connected to both ends of the above-mentioned coil core, may have the corners of the outer connection parts formed in a round shape to prevent magnetic force from radiating into the surrounding space.

[0047] The steel materials of the above N and S poles can be processed to maintain a higher average magnetic flux density, and additionally form checkerboard-shaped irregularities on the pole surface formed after lamination.

[0048] The above auxiliary stimulus may be configured to be placed in a layer where the S pole corresponding to the N pole and the N pole corresponding to the S pole are alternately omitted.

[0049] The above auxiliary stimuli may be configured to be connected to the steel materials of the N pole and the S pole, respectively, and to make point contact, line contact, or surface contact depending on the contact surface condition of the adsorbate when adsorbed to the adsorbate.

[0050] The areas of the N pole and the S pole are the same or similar, the spacing between the N pole and the S pole is constant, and the shapes of the N pole and the S pole are the same, but even if the shapes are different, the length of the angled corners where magnetic force is concentrated on the magnetic pole surface may be the same.

[0051] The reinforcing structure that protects the solenoid winding of the magnet lifter unit and supports the N and S poles of the magnet lifter unit in the above magnet lifter unit and the reinforcing structure that connects the plurality of magnet lifter units to form a pot may be made of non-magnetic steel.

[0052] According to an embodiment of the present invention, by increasing the average magnetic flux density of the magnet lifter, the adsorption force (magnetic force) is strengthened and the lifter becomes lighter, thereby reducing the burden on the crane due to improved performance and eliminating the need for reinforcement of the building structure, while improving logistics productivity and reducing the magnetization power required for the lifter and the movement power of the crane, and effectively providing a magnet lifter assembly in which magnetic force acts while preventing loss of magnetic force due to air gaps through various contact methods depending on the condition of the steel material to be adsorbed.

[0053] In addition, according to the magnet lifter of the embodiment of the present invention, first, the average magnetic flux density at the magnetic surface of the magnet lifter is maintained at a higher magnetic flux density than that of a simple integrated magnetic surface; second, the magnetic flux density at the magnetic surface is uniformized, making it easy to control the magnetic force through current control, thereby providing stable control of the number of items; third, since the average magnetic flux density is high and the magnetic force becomes stronger, it is possible to lift heavier steel products, thereby improving logistics productivity. Fourth, through the lightweighting of the magnet lifter, steel products of the same weight can be lifted with a lighter lifter, reducing the burden on the crane and creating a margin in the lifting rating, and since the lifter is light, the power consumption of the crane can also be reduced; and fifth, as the magnetic force transmission path between the magnet lifter and the steel product to be adhered to becomes more diverse and increased, magnetic force loss due to the air gap is minimized, making it possible to achieve an optimal design without over-design.

[0054] The effects according to the present invention are not limited to those exemplified above, and various other effects are included in this specification.

[0055] FIG. 1 is a drawing showing a conveying system for steel plate products to which a magnet lifter according to an embodiment of the present invention is applied.

[0056] FIG. 2 is a drawing showing a magnet lifter driving system according to an embodiment of the present invention.

[0057] Figure 3 shows a hysteresis curve and a magnetic characteristic curve that weakens depending on the size of the air gap between the magnetic pole and the adsorbed iron material.

[0058] FIGS. 4a to 4e are drawings illustrating a magnet lifter unit according to an embodiment of the present invention and a cross-section illustrating a magnetic surface processed to maintain a higher average magnetic flux density on the magnetic surface of the magnet lifter unit.

[0059] FIG. 4c is a laminated pole surface after the pole surface of the laminated square steel is processed as in FIG. 4d to maintain a higher average magnetic flux density at the pole surface.

[0060] FIG. 4d is a drawing illustrating a method for processing each steel material stacked to maintain a high average magnetic flux density on the magnetic pole surface of a magnet lifter unit according to an embodiment of the present invention.

[0061] Figure 5 is a drawing illustrating a steel lamination method in which type “A” and type “B” are laminated in an alternating manner.

[0062] Figure 6a is a drawing showing the case where a rod-shaped auxiliary stimulus is applied to a lifter for steel plates or cylindrical or severely curved steel products, and Figure 6b is a drawing showing the case where a fan-shaped auxiliary stimulus is applied to a lifter for cylindrical steel products.

[0063] FIGS. 7a to 7c are drawings showing magnetic lifter stimulation planes for steel plates currently in use, where FIG. 7a is a magnetic lifter unit stimulation plane for steel plates, FIG. 7b is a magnetic lifter unit pot stimulation plane for wide, long steel plates that shares a border with an adjacent lifter unit, and FIG. 7c is a drawing showing a magnetic lifter stimulation plane for general steel products other than steel plates, such as structural steel and reinforcing bars.

[0064] The present invention is not limited to the embodiments described below but can be implemented in various different forms. These embodiments are merely illustrative of the content of the present invention and are provided to inform those skilled in the art of the scope of the invention in detail. The present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0065] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the illustrated regions are depicted for the effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of the device regions and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0066] The terms used herein are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0067] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0068] Hereinafter, the concept of the present invention and embodiments according thereto will be described in detail with reference to the drawings.

[0069] As illustrated in FIG. 1, a steel product transport system according to an embodiment of the present invention may be configured to include a crane (99) and a magnet lifter operation system (or lifter control system) (100) installed on the crane (99) as in FIG. 2 to lift various steel products such as steel plates, coils, wire rods, structural steel, reinforcing bars, and scrap. Here, the magnet lifter operation system (100) may be configured to include a plurality of lifter assemblies (110), called magnet lifter units or pots, which include a magnetic force control device (220).

[0070] As can be seen in FIG. 1, it may be configured to include a plurality of lifter unit assemblies (Fig. 7b) called magnet lifter units or Pots connected to a crane (99). Here, the Pot is a combined assembly formed by mechanically connecting a plurality of lifter units (Units or unit lifters), and all solenoid windings of the lifter units are connected in parallel so that the same voltage is applied to each winding.

[0071] Additionally, multiple magnet lifter units (210_1 to 210_N) constituting the port can be arranged and configured to maintain a specified spacing (L) so as not to cause interference with adjacent magnet lifter units, more precisely, magnetic cancellation, and multiple ports are used to lift steel plates with a width of up to 5.5m, a length of 23m, and a thickness (d) of 22mm or greater.

[0072] At this time, the length of the long axis direction of the lifter assembly (110) can be varied depending on the horizontal length of the steel plate.

[0073] In addition, as seen in FIG. 1, adjacent lifter assemblies (110) installed on the crane (99) can be spaced apart from each other. This can be achieved by controlling the equipment operation of the crane (99). This spacing adjustment can be varied depending on the type of steel products that are adsorbed to the lifter assemblies (110) and transported to a designated destination.

[0074] Unlike flat steel products, cylindrical or other shaped steel products have different contact surface shapes; therefore, instead of a Pot, multiple magnetic lifter units (or permanent lifter units) are used to lift the steel products according to their size and weight, and in this case, the multiple units are installed on a single support structure.

[0075] The magnetic control device (220) of FIG. 2, which constitutes the operating system (100) according to an embodiment of the present invention, is composed of a converter that rectifies and adjusts the AC power applied to the crane (99), a demagnetizing device that removes residual magnetism by applying AC power after cutting off the DC power applied to the magnet lifter unit or port, and a magnetic holding circuit (or time delay circuit) that delays the operation of the crane's hoisting motor for a certain period of time while removing residual magnetism simultaneously with cutting off the DC power.

[0076] The configuration of the magnet lifter control system (or operating system) is divided into cases for steel plates and cases not for steel plates. For general use, there is one or multiple magnet lifter units, or for steel plates, multiple units form a single port. Multiple ports are installed on a crane through a single support structure to lift a steel plate with a width of 5.5 × length of 23m, and the solenoid windings of all units are connected in parallel. Whether for general use or for steel plates, the current method of power supply is to rectify AC power and connect it in parallel. However, in the control system according to the embodiment of the present invention, AC power is rectified using a converter through the control device (220) and the voltage and current are adjusted. When DC power is turned off immediately after use, the Magnet Holding or Delay circuit is operated to a) disconnect the DC applied to the magnet, b) temporarily stop the operation of the hoisting motor installed on the crane lifting the magnet, and c) apply AC power to the magnet winding to demagnetize it. For example, the hysteresis demagnetization system removes residual magnetism by attenuating the applied current value from 60Hz alternating current to “0” (Zero) within 1 to 5 seconds. In addition, the control device (220) operates the hoisting motor after demagnetization to hoist the demagnetized magnet, and then the crane moves.

[0077] At this time, suspending the crane's hoisting motor for a certain period using a Magnet Holding or Time Delay circuit while the magnet is in contact with the lowered object is intended to partially demagnetize the magnetized object.

[0078] In addition, in an embodiment of the present invention, a magnet driving system equipped with a magnetic force control system capable of controlling the average magnetic flux density by controlling the applied power through a magnetic force control device (220) can be configured. The magnetic force control device (220) can control the strength of the DC voltage applied to the magnet lifter unit (210_1 ~ 210_N), more precisely the strength of the current, so that, for example, a flat steel plate can be lowered one by one at each destination, and at the final destination, after all the steel plates have been lowered, the DC voltage is cut off and AC power is temporarily applied to the magnet lifter unit (210_1 ~ 210_N), thereby making it possible to remove even the residual magnetism of the adsorbed object.

[0079] Table 2 shows a magnetic lifter product for wire rods with a large air gap due to external curvature such as irregularities.

[0080] [Table 2]

[0081]

[0082] Basically, the contact points of iron products lifted by magnetic force become magnetized, but the magnetization disappears within a short period of time.

[0083] In addition, if the magnetic force is strengthened when lifting multiple sheets, claims are expected due to the magnetization of the steel plates that come into direct contact with the lifter. Since the magnetic pole surface, which is composed of a single mass of magnetic material, is not uniform in the shape of a horn with a large difference in magnetic flux density between the center where the magnetic flux density is "0" and the corners of the angular edges where the magnetic flux is concentrated, the control of the last 1 to 2 sheets is unstable when lifting multiple steel plates and lowering one or several sheets to various locations.

[0084] In addition, when the magnetic lifter is used and the power is cut off, the magnetic force on the pole surface does not disappear for a considerable amount of time, and if the residual magnetism that remains is not removed and the lifter continues to be used, magnetic disturbance occurs, weakening the performance of the lifter. Furthermore, foreign substances adhere to the pole surface due to the residual magnetism, causing damage to the steel plate surface and resulting in claims. Since the change in the polarity of the applied DC current is being misused for demagnetization in the field, it is necessary to remove it using the hysteresis method, which is a natural characteristic.

[0085] In order to solve the above problem, each magnet lifter unit (210_1 ~ 210_N) constituting the lifter assembly (110) or magnet lifter according to an embodiment of the present invention is a magnet lifter installed on a crane (99) to lift various iron products such as steel plates, wire rods, structural steel, rebar, and scrap, and is a magnet lifter in which the area of ​​the N pole and the S pole are the same or similar, the spacing between the N and S poles is constant, the shape or form of the magnetic poles is the same or similar (or similar), and the length of the angled corners processed to concentrate magnetic force on the magnetic pole surface is the same so that the average magnetic flux density is maintained, so that the average magnetic flux density on the N and S magnetic pole surfaces is the same and close to the saturation value of 1.5 Tesla, and auxiliary magnetic poles are installed to reinforce the air gap between the magnetic pole surface, which is cylindrical or has a surface with severe curvature and unevenness and thus has a large magnetic force loss due to the air gap, and the iron product, so that line and point contact are added to the contact method between the lifter and the object to be adsorbed, thereby providing a magnetic force optimized for the appearance of the object to be adsorbed. A lifter having a delivery structure can be formed (or configured, provided).

[0086] In addition, the magnet lifter unit (210_1 to 210_N) according to the embodiment of the present invention has a magnetic flux density of 1.5 Tesla (or 15,000 Gauss) at the maximum value on the surface of the magnetic iron, and the magnetic flux density is "0" at the center of the magnetic surface and the magnetic force is concentrated at the angled corners of the surface. Therefore, a magnetic surface can be formed by stacking square steel plates and dividing the stacked magnetic surface into a grid pattern like a checkerboard to provide angled corners, thereby forming a high average magnetic flux density on the magnetic surface.

[0087] In addition, the magnet lifter unit (210_1 to 210_N) according to the embodiment of the present invention can maintain the same area, state, and shape of the N pole and the S pole in a ‘C’-shaped lifter in which the N pole and the S pole are formed by assembling a solenoid winding on a winding core made of multiple rectangular steel plates stacked together and assembling a magnetic core at both ends of the core in the same right-angle direction. At this time, if the gap between the stacked steel plates is “0”, the stacked corners overlap, so in the core composed of N pole and S pole, the S pole corresponding to the N pole and the N pole corresponding to the S pole are alternately omitted one pole at a time, and the gap between the corners is maintained by the thickness of the stacked steel plates. In the magnetic core, if one N pole is made of steel, the S pole of the same layer is an auxiliary magnetic pole, and if another S pole is made of steel, the N pole corresponding thereto is an auxiliary magnetic pole, so that they are alternately stacked to prevent magnetic loss due to an air gap with the auxiliary magnetic pole, and the effective area where the magnetic force acts can be wider than the original magnetic pole surface.

[0088] In addition, the magnet lifter unit (210_1 to 210_N) according to the embodiment of the present invention may have a structure in which all corners through which magnetic flux passes, excluding the magnetic pole surface that directly contacts the iron product in all stacked square steel plates, are rounded so that magnetic force is not emitted into the surrounding space from the angled corners.

[0089] In addition, the magnet lifter unit (210_1 to 210_N) according to an embodiment of the present invention may be processed such that the outer connection portion of the magnetic pole core, which is connected at a right angle to the solenoid core, is rounded (more precisely, not angled) to prevent magnetic force from radiating into space from the angled corners and to concentrate it on the object to be adsorbed. Magnetic field lines generated from the N pole flow within the magnetic material, but if the magnetic field lines become saturated within the magnetic circuit or there is no smooth path, they radiate into the surrounding space and inevitably return to the S pole; they radiate preferentially while concentrating on angled or sharp corners.

[0090] Due to these regression characteristics, malfunctions of surrounding control devices and collisions with surrounding objects occur. In an embodiment of the present invention, to improve this problem, all edges other than the stimulation surface in contact with the adsorbed steel can be machined into a rounded shape.

[0091] To summarize, the magnet lifter according to the embodiment of the present invention, or the magnet lifter unit (210_1 to 210_N) constituting said lifter, is a structure made according to the principle that in a logistics lifter using a magnet lifter or permanent lifter, the N pole and S pole maintain a constant spacing and the same area, the shape of the magnetic poles is the same or similar, and the length of the angled corners where magnetic force is concentrated on the magnetic pole surface is also processed to be the same. It can be seen as having a lifter structure that maintains the average magnetic flux density on each magnetic pole surface as the same or similar and close to the natural saturation value of 1.5 Tesla. In addition, the outer edge of the part connected at a right angle in the winding core where the solenoid winding is assembled is processed into a circle, and all remaining corners except the corner of the magnetic pole surface that contacts the adsorbed iron product in the magnetic pole core made of laminated rectangular steel plates are processed into a circle so that the magnetic force generated in the magnet lifter or permanent lifter is concentrated only on the lifting of the iron product adsorbed. When stacking rectangular steel plates, each N and S pole surface is processed into a grid pattern, and the N and S poles of each stacked layer are configured to correspond (or match) with each other as N (pole) and auxiliary pole, and S pole and auxiliary pole. This configuration ensures a wider effective magnetic surface area than the stacked pole surface when lifting steel plates, and allows for a structure where magnetic force acts with minimal loss when lifting cylindrical or severely curved steel products. Additionally, for cylindrical or severely uneven steel products to be lifted, the pole surface can be sloped, and a lifter with an optimized structure can be configured to allow magnetic force to act effectively using auxiliary poles while minimizing magnetic loss caused by air gaps.

[0092] The magnet lifter unit (210_1, ..., 210_N) according to an embodiment of the present invention can be configured in various forms when forming the steel core (400), but it can be formed in a form in which a winding core (401) made by stacking multiple rectangular steel plates and a magnetic core (402_1, 402_2) formed at both ends of the winding core (401) in the same right-angle direction. This is clearly shown in FIG. 4d. Since a solenoid wire (410) is wound on the winding core (401), it may also be named a solenoid core. In an embodiment of the present invention, the solenoid winding core is configured such that all steel plates are stacked without omission, and the magnetic core (402_1, 402_2) is configured such that "A" type and "B" type are stacked alternately as N and S poles, and the missing pole portions are filled with auxiliary magnetics. The fixing method can be varied, such as forming a magnetic core (402_1, 402_2) at each end of the coil core (401) and drilling a hole to fasten it with a screw. It will not be limited to such methods.

[0093] Of course, when the iron core (400) forming the N pole and the iron core (400) forming the S pole are sequentially stacked, the auxiliary stimuli formed in the empty space can have various shapes, and in the embodiment of the present invention, the ends of the stimulating iron cores (402_1, 402_2) of the N pole and S pole are configured in various shapes according to the surface shape of the adsorbed object, which is a various type of steel product, and are made in contact so that the magnetic force acts effectively.

[0094] As will be further examined later through FIGS. 5 and 6, it may be preferable for the auxiliary stimulus according to the embodiment of the present invention to be formed in a fluid form when adsorbed to the surface of the object to be adsorbed. The auxiliary stimulus is fixed to the front and back (or top and bottom) steel plates with a pivot as the axis, maintaining a constant angle of at least 30 degrees with respect to the vertical line, and when the magnet contacts the object to be adsorbed, it naturally contacts the curvature of the surface of the object to be adsorbed due to its own weight.

[0095] In addition, the shape of the auxiliary stimulus and the angle with the vertical line will vary depending on the external condition of the adsorbate, such as irregularities or curves.

[0096] FIG. 6a is a drawing showing an example of an auxiliary stimulus applicable to a magnet lifter unit for steel plates according to an embodiment of the present invention. FIG. 6b is a drawing showing an example of an auxiliary stimulus applicable to a magnet lifter unit for cylindrical steel products or steel products with severe surface curvature and irregularities. Here, reference numeral 540_1 represents an auxiliary stimulus pivot, and reference numeral 540_2 represents an auxiliary stimulus angle maintaining fixator.

[0097] The auxiliary stimulus (530) is fixed to the iron core of the same stimulus above or below (or to the left and right) by the pivot and the stator. When the lifter unit contacts the object to be adsorbed, if the surface of the object to be adsorbed is flat, the auxiliary stimulus (530) operates to maintain a horizontal position relative to each other, thereby widening the effective contact surface with the flat surface. Additionally, if the object to be adsorbed is a cylindrical coil or a cylindrical steel product with severe curvature or irregularities, the adsorption force can be increased by contacting, or adsorbing, in a manner that wraps around the product. In the embodiment of the present invention, the auxiliary stimulus (620) is configured to adsorb according to the shape of the surface of the object to be adsorbed, so that the adsorption force is effectively applied through point, line, and surface contact.

[0098] Additionally, FIG. 6b shows that the shape of the auxiliary stimulus (530) may vary. Most importantly, the auxiliary stimulus (530, 620) constituting the magnet lifter unit (210_1, ..., 210_N) according to the embodiment of the present invention can have various shapes, and together with this, the end portion of the stimulus core (610_1, 610_2) can also be changed in various ways. The shape of the auxiliary stimulus (530, 620) or the shape of the end portion of the stimulus core (610_1, 610_2) can be seen as having a shape that maintains maximum adsorption force through point, line, or surface contact according to the surface shape of the object to be adsorbed, in order to flexibly respond to various types of steel products.

[0099] Although all components constituting an embodiment of the present invention have been described as being combined or operating in combination, the present invention is not necessarily limited to such an embodiment. That is, within the scope of the purpose of the present invention, all components may be selectively combined in one or more ways to operate.

[0100] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the invention as claimed in the claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention.

Claims

1. In a lifter that is overall "C"-shaped, composed of a solenoid winding assembled on an iron core made of laminated rectangular magnetic steel plates and N and S poles connected at the same right angle from both ends of the iron core, the spacing between the N and S poles is constant, and the lengths of the angled corners configured to concentrate magnetic force on the magnetic pole surface are processed to be equal for the N and S poles, thereby maintaining the magnetic flux density at the N and S poles as equal and close to 1.5 Tesla, which is the saturation value due to natural characteristics, and A magnet lifter unit having a structure in which the magnetic surface composed of laminated steel plates is processed with angled corners in a checkerboard shape to maintain the average magnetic flux density of the surface close to the saturation value of 1.5 Tesla, and the laminated steel plates are laminated with one layer missing so that the angled corners do not overlap, and auxiliary magnetic plates are assembled in the missing spaces of the S pole corresponding to the missing N pole and the N pole corresponding to the S pole, thereby minimizing magnetic loss caused by air gaps resulting from line contact and point contact in addition to surface contact with the object to be adsorbed.

2. It has a converter that rectifies AC power applied to a crane unit equipped with a magnet lifter into DC and adjusts the average magnetic flux density at the magnetic pole surface by adjusting the rectified current, and a hysteresis-type demagnetizing device that removes residual magnetism between the lifter and the object to be adsorbed by applying AC instead of DC while temporarily delaying the operation of the crane's hoisting motor using a magnetic holding or time delay circuit installed when the current is cut off to stop the activity of the magnet lifter. The above magnet lifter includes a magnet lifter unit, and The above magnet lifter unit is, In a lifter that is "C" shaped overall, consisting of a solenoid winding assembled on an iron core made of laminated rectangular magnetic steel plates and N and S poles connected at the same right angle from both ends of the iron core, the spacing between the N and S poles is constant, and the lengths of the angled corners configured to concentrate magnetic force on the magnetic pole surface are processed to be equal for the N and S poles, thereby maintaining the magnetic flux density at the N and S poles as equal and close to 1.5 Tesla, which is the saturation value due to natural characteristics. The above magnet lifter unit is, A magnet lifter control system having a structure in which the magnetic surface composed of laminated steel plates is processed with angled corners in a checkerboard shape to maintain the average magnetic flux density of the surface close to the saturation value of 1.5 Tesla, and the laminated steel plates are laminated with one layer missing so that the angled corners do not overlap, and auxiliary magnetic plates are assembled in the missing spaces of the S pole corresponding to the missing N pole and the N pole corresponding to the S pole, thereby minimizing magnetic loss caused by air gaps resulting from line contact and point contact in addition to surface contact with the object to be adsorbed.

3. In Paragraph 2 The above-mentioned installed magnetic holding or time delay circuit is, A magnet lifter control system that, when the DC current applied to the magnet lifter is cut off, delays the operation of the crane's hoisting motor while maintaining contact with the object to be absorbed, and causes a demagnetizing device to operate to remove residual magnetism between the lifter and the object to be absorbed.

4. In Paragraph 1 A magnet lifter unit having a structure that maintains a vertical line and an inclination of 30 degrees or more by means of a pivot and an angle fixer that fix the auxiliary stimulus so that it contacts the adsorbate by its own weight when in contact with the adsorbate.

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