KR-102963150-B1 - Method for suspending a steel plate by a lifting magnet, a lifting magnet, and a method for manufacturing a steel plate using a lifting magnet

KR102963150B1KR 102963150 B1KR102963150 B1KR 102963150B1KR-102963150-B1

Abstract

When lifting steel plates using a lifting magnet, the magnetic flux penetration depth is controlled with high precision according to the plate thickness or the number of plates to be lifted, and a desired number of steel plates are lifted reliably and stably regardless of the plate thickness. A lifting magnet (1) is used, which is equipped with a plurality of electromagnet coils (2) capable of independently controlling ON-OFF and voltage, and a magnetic pole (3) that is energized by applying voltage to the electromagnet coils (2). The electromagnet coils (2) used for lifting the steel plate are determined based on the total thickness of the steel plate to be lifted. The amount of magnetic flux passing through the magnetic pole (3) (Φ r ) is calculated in the case where the magnetic flux passes only through the steel plate to be lifted when the electromagnet coils (2) are used. Based on this amount of magnetic flux passing through (Φ r ), the applied voltage to the electromagnet coils (2) used for lifting the steel plate is determined, and the applied voltage is applied to the electromagnet coils (2).

Inventors

다카키 유키
다케무라 유사쿠
구리모토 아츠시
가와이 아야카

Assignees

제이에프이 스틸 가부시키가이샤

Dates

Publication Date: 20260508
Application Date: 20211215
Priority Date: 20210226

Claims (10)

A method of lifting only at least one steel plate to be lifted from among multiple overlapping steel plates using a lifting magnet, The lifting magnet described above comprises a plurality of electromagnet coils capable of independent ON-OFF control and voltage control, a magnetic pole that is excited by the application of voltage to the electromagnet coils, a control device for controlling the lifting of the steel plate, a magnetic flux sensor for measuring the amount of magnetic flux (Φa) passing through the magnetic pole, and a weight measuring means for measuring the weight of the lifted steel plate. Based on the total sum of the plate thicknesses of the steel plates to be lifted, the electromagnet coil used for lifting the steel plates is determined, and Calculate the amount of magnetic flux passing through the magnetic pole (Φ r ) in the case where the magnetic flux flowing out from the magnetic pole when the above-mentioned electromagnet coil is used passes only through the steel plate of the object to be lifted, and Based on the above amount of passing magnetic flux (Φ r ), the applied voltage to the electromagnet coil used for suspending the steel plate is determined, and The above applied voltage is applied to the electromagnet coil, and only the steel plate to be lifted is lifted from among the multiple overlapping steel plates, and A method for lifting a steel plate by a lifting magnet, wherein, after applying the applied voltage to the electromagnet coil to initiate lifting a steel plate by the lifting magnet, and before moving the lifting magnet in the state of lifting the steel plate, the control device determines whether the difference between the amount of magnetic flux passing through the magnetic pole (Φr) calculated by the control device and the amount of magnetic flux passing through the magnetic pole (Φa) measured by the magnetic flux sensor is below a threshold value, thereby checking whether the number of steel plates lifted matches a predetermined number of steel plates to be lifted, and if the number of steel plates lifted matches a predetermined number of steel plates to be lifted because the difference is below the threshold value, the control device also checks whether the number of steel plates lifted matches a predetermined number of steel plates to be lifted based on the weight of the steel plate measured by the weight measuring means.
In paragraph 1, A method for suspending a steel plate by a lifting magnet, wherein when the applied voltage is applied to the electromagnet coil, the difference between the amount of magnetic flux passing through the calculated magnetic pole (Φ r ) and the amount of magnetic flux passing through the magnetic pole measured by a magnetic flux sensor (Φ a ) is less than or equal to a threshold value.
In paragraph 1 or 2, A method for suspending a steel plate using a lifting magnet, wherein the amount of magnetic flux passing through the magnetic pole (Φ r ) is calculated based on the plate thickness and saturation magnetic flux density of each steel plate to be suspended, and the size of the magnetic pole energized by the application of the applied voltage to the electromagnet coil.
In paragraph 1 or 2, A method for lifting a steel plate by a lifting magnet, wherein after initiating the lifting of a steel plate by the lifting magnet, before moving the lifting magnet while the steel plate is in a lifted state, either or both of the following (I) and (II) are performed. (I) Increase the applied voltage to the electromagnet coil used for lifting the steel plate. (II) In addition to the above electromagnet coil used for lifting the steel plate, voltage is applied to one or more other electromagnet coils.
In paragraph 1 or 2, The above lifting magnet is a method for suspending a steel plate by a lifting magnet having a plurality of electromagnet coils arranged concentrically and vertically in layers in either or both directions of the up and down.
A plurality of electromagnet coils, each capable of independent ON-OFF control and voltage control, and A magnetic pole energized by the application of voltage to the electromagnet coil, and A control device configured to determine an electromagnet coil used for lifting the steel plate based on the total sum of the plate thicknesses of the steel plate to be lifted when lifting only at least one steel plate to be lifted from among a plurality of overlapping steel plates, calculate the amount of magnetic flux passing through the magnetic pole (Φ r ) in the case where the magnetic flux flowing out from the magnetic pole when the electromagnet coil is used passes only through the steel plate to be lifted, determine an applied voltage to the electromagnet coil used for lifting the steel plate based on the amount of magnetic flux passing through (Φ r ), and apply the applied voltage to the electromagnet coil. A magnetic flux sensor that measures the amount of magnetic flux (Φa) passing through the magnetic field, and A weight measuring means for measuring the weight of a suspended steel plate Equipped with, A lifting magnet. The above control device, after applying the applied voltage to the electromagnet coil to start lifting the steel plate and before moving the steel plate in the lifted state, determines whether the difference between the amount of magnetic flux passing through the magnetic pole (Φr) calculated by the control device and the amount of magnetic flux passing through the magnetic pole (Φa) measured by the magnetic flux sensor is below a threshold value, thereby checking whether the number of lifted steel plates matches a predetermined number of steel plates to be lifted, and if the number of lifted steel plates matches a predetermined number of steel plates to be lifted due to the difference being below the threshold value, further checks whether the number of lifted steel plates matches a predetermined number of steel plates to be lifted based on the weight of the steel plate measured by the weight measuring means.
In paragraph 6, A lifting magnet configured such that, when the applied voltage is applied to the electromagnet coil, the difference between the amount of magnetic flux passing through the calculated magnetic pole (Φ r ) and the amount of magnetic flux passing through the magnetic pole measured by a magnetic flux sensor (Φ a ) is less than or equal to a threshold value.
In paragraph 6 or 7, The above-described control device is a lifting magnet configured to calculate the amount of magnetic flux passing through the magnetic pole (Φ r ) based on the plate thickness and saturation magnetic flux density of each steel plate of the lifting target and the dimensions of the magnetic pole energized by the application of the applied voltage to the electromagnet coil used.
In paragraph 6 or 7, A lifting magnet having a plurality of electromagnet coils arranged in layers in either one or both concentric and vertical directions.
A method for manufacturing a steel plate using a lifting magnet as described in paragraph 6 or 7.

Description

Method for suspending a steel plate by a lifting magnet, a lifting magnet, and a method for manufacturing a steel plate using a lifting magnet The present invention relates to a lifting method for suspending and transporting a steel plate by means of a lifting magnet in, for example, a steel mill or a steel processing plant, a lifting magnet suitable for implementing the same, and a method for manufacturing a steel plate using the lifting magnet. The heavy plate mill of a steelworks is broadly equipped with rolling equipment (rolling process) that rolls massive steel material to a desired thickness, precision finishing equipment (precision finishing process) that performs cutting to shipment size, deburring of ends, finishing of surface defects, and inspection of internal defects, and a product warehouse that stores steel plates (heavy plates) awaiting shipment. Steel plates that are to be worked on in the precision sorting process or are awaiting shipment in the product warehouse are stored in a stacked state, ranging from several to dozens of sheets, due to space constraints. When changing the arrangement of steel plates or shipping them, an electromagnetic lifting magnet attached to a crane is used to lift and move the steel plates (one to several sheets) to be worked on. The internal structure of a general electromagnetic lifting magnet is shown in FIG. 16 (cross-sectional view). The lifting magnet has a coil (100) with a diameter of 100 to several hundred mm inside. An inner pole (101) (inner pole core) is arranged on the inner side of the coil (100), and an outer pole (102) (outer pole core) is arranged on the outer side of the coil (100). A yoke (103) is fixed in contact with the upper end of the inner pole (101) and the upper end of the outer pole (102). In this lifting magnet, when the coil (100) is energized, the inner pole (101) and the outer pole (102) come into contact with a steel plate, thereby forming a magnetic field circuit and attracting the steel plate. The lifting magnet used in the steel mill generates magnetic flux using one large coil (100) to secure sufficient lifting force. Typically, it is designed so that the magnetic flux density passing through the inner pole (101) is 1T (= 10000G) or more. To control the number of steel plates adsorbed by a lifting magnet, it is necessary to control the penetration depth of the magnetic flux based on the plate thickness and the number of plates to be lifted. However, conventional lifting magnets make it difficult to control the magnetic flux penetration depth with high precision. Consequently, when lifting a predetermined number of steel plates, it is operationally difficult to adsorb only that number from the very beginning. Therefore, the number of plates adsorbed is adjusted by first adsorbing a larger quantity and then dropping the excess amount through current adjustment or on/off operations of the lifting magnet. However, under this method, depending on the skill of the crane operator, multiple retries may occur, leading to a significant decrease in work efficiency. Furthermore, this adjustment process for the number of plates adsorbed also serves as a major obstacle to crane automation. To resolve this problem, a method (Patent Document 1) has been proposed as a technology that enables automatic control of the number of steel plates lifted, wherein the lifting force is controlled by controlling the current applied to the coil of the lifting magnet. FIG. 1 is a cross-sectional view schematically showing one embodiment of a lifting magnet used in the present invention, wherein a plurality of electromagnet coils are arranged concentrically. Figure 2 is a horizontal cross-sectional view of the lifting magnet of Figure 1. FIG. 3 is an explanatory diagram for explaining the principle of the present invention. Figure 4 is a flowchart illustrating the process of the present invention. FIG. 5 is an explanatory diagram showing the flow of magnetic flux within the superimposed steel plates when a portion of the electromagnet coil is energized in the present invention. FIG. 6 is a diagram (cross-sectional view of the lifting magnet) showing a state in which, in one embodiment of the present invention using the lifting magnet of FIG. 1 and FIG. 2, when the electromagnet coil on the inner layer side is energized, the magnetic flux flowing out from the magnetic pole passes only through the steel plate to be lifted. FIG. 7 is a diagram (cross-sectional view of a lifting magnet) showing a state in which the amount of magnetic flux (magnetic flux penetration depth) is increased by increasing the applied voltage to the electromagnet coil on the inner side after lifting the steel plate from the state of FIG. 6. FIG. 8 is a diagram (cross-sectional view of a lifting magnet) showing a state in which the amount of magnetic flux (magnetic flux penetration depth) is increased by energizing the outer layer electromagnet coil in addition to the inner layer electr