A control method based on the electromagnetic crane steel plate single release function

Abstract

The application discloses a control method based on a single release function of a magnetic crane steel plate electromagnet, and the control method can ensure that the working voltage of the magnetic crane electromagnet is unchanged in single lifting work, and through the single release function of the magnetic crane electromagnet, the lifted multiple steel plates are lowered one by one, so that the target steel plate is located at the lowermost position of the magnetic crane adsorption and the single quick lifting work is completed.

Description

Technical Field

[0001] This invention relates to a control method for an overhead crane electromagnetic hoist, and more particularly to a control method based on the single-sheet release function of an overhead crane electromagnetic hoist. Background Technology

[0002] In steel rolling mills, steel plates are typically hoisted using electromagnetic chucks mounted on overhead cranes. Under normal production conditions, the number of steel plates to be hoisted by the crane is substantial. When hoisting thinner plates, operators often struggle to control the number of plates being lifted at once, sometimes lifting three to four plates at a time. However, when only one plate from any given layer is needed, the existing electromagnetic chucks on most cranes can only control the suction force by adjusting their operating voltage. If operators were to continuously adjust the voltage to hoist a specified number of plates, it would be extremely time-consuming, inefficient, and demand a high level of operator skill. Therefore, it is necessary to add a single-plate release function based on the control principles and operation of the electromagnetic chucks, thereby enabling rapid hoisting of steel plates by the crane.

[0003] There is a need for a control method based on the single-sheet release function of the electromagnetic chuck of an overhead crane. This method can release multiple steel sheets one by one through the single-sheet release function of the electromagnetic chuck during a single lifting operation, while ensuring that the working voltage of the electromagnetic chuck remains constant. This allows the target steel sheet to be placed at the lowest position of the electromagnetic chuck and completes the single-sheet rapid lifting operation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a control method based on the single-sheet release function of a crane electromagnetic chuck. This control method based on the single-sheet release function of a crane electromagnetic chuck can lower multiple steel sheets one by one through the single-sheet release function of the crane electromagnetic chuck while ensuring that the working voltage of the electromagnetic chuck remains unchanged during a single hoisting operation. This allows the target steel sheet to be located at the lowest layer of the electromagnetic chuck and completes the single-sheet rapid hoisting operation.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A control method based on the single-sheet release function of an overhead crane electromagnetic hoist includes the following steps:

[0007] Step 1: Pre-treatment of the target steel plate before single-sheet release: The electromagnetic crane includes an electromagnetic crane base and electromagnetic crane suction cups. Several electromagnetic crane suction cups are parallel to each other and evenly distributed at the same intervals below the electromagnetic crane base. The steel plate storage stack contains several steel plates of the same length and thickness but different numbers. The pre-treatment of the target steel plate by the electromagnetic crane before single-sheet release specifically includes the following steps:

[0008] Step 1A: Set the working voltage V of the electromagnetic crane and turn on several adjacent electromagnetic crane suction cups.

[0009] Step 1B: Determine the layer m of the steel plate storage stack where the steel plate to be hoisted is located. Move the electromagnetic crane to a position directly above the steel plate storage stack. Lower the electromagnetic crane until the bottom of the electromagnetic crane suction cup is completely in contact with the steel plate at the top of the steel plate storage stack. Then raise the electromagnetic crane so that the operator can confirm the number of steel plates n that the electromagnetic crane has attracted at this time. n is the thickness of the current steel plate, which corresponds to the maximum number of steel plates that the electromagnetic crane can hoist in a single operation.

[0010] Step 1C: When m≤n, the pre-treatment of the target steel plate before single-sheet release is completed; when x×n<m≤(x+1)×n, where x≥2, the adsorbed steel plate is hoisted to the remaining steel plate storage area, and the adsorption of steel plates is repeated and hoisted to the remaining steel plate storage area x times, with the number of steel plates adsorbed each time being n. At this time, the electromagnetic crane is operated again to run to the steel plate storage area and adsorb n steel plates. The electromagnetic crane is raised so that the operator can confirm the number of steel plates adsorbed by the electromagnetic crane at this time, thus completing the pre-treatment of the target steel plate before single-sheet release.

[0011] Step 2, hoisting the target steel plate, specifically includes the following steps:

[0012] Step 2A: When the target steel plate is at the bottom layer of the electromagnetic crane, control the electromagnetic crane to move vertically above the target steel plate storage area, and lower the electromagnetic crane to a distance h between the bottom surface of the target steel plate and the target steel plate storage area. At this time, the operator presses the electromagnetic crane power-off button and keeps it pressed. The electromagnetic crane suction cup stops supplying power. When the target steel plate begins to fall relative to the target steel plate storage area, the operator releases the electromagnetic crane power-off button, the electromagnetic crane suction cup resumes power supply, the electromagnetic crane rises, and the remaining steel plate is lifted to the steel plate storage stack, completing the lifting operation of the target steel plate.

[0013] Step 2B: When the target steel plate is not at the bottom layer of the electromagnetic crane, adjust the height of the electromagnetic crane so that the distance between the bottom surface of the bottom layer of the electromagnetic crane and the top surface of the top layer of the steel plate in the stack is h. At this time, the operator presses the electromagnetic crane power off button and keeps it pressed. The electromagnetic crane suction cup stops supplying power. When the bottom layer of the steel plate begins to fall relative to the stack of steel plates, the operator releases the electromagnetic crane power off button, and the electromagnetic crane suction cup resumes power supply.

[0014] Step 2C: Determine whether the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate. If the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate, perform step 2A to complete the lifting of the target steel plate. If the target steel plate is not at the bottom layer of the electromagnetic crane's adsorption plate, repeat step 2B until the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate, then perform step 2A to complete the lifting of the target steel plate.

[0015] In step 1A, let the length of the steel plate being lifted be l1. The electromagnetic crane opens several adjacent electromagnetic suction cups according to the length l1 of the steel plate. The distance between the electromagnetic suction cups that are opened and located at the two ends is l2. l2 should satisfy: 1m < l1 - l2 < 2m, and the distance between the electromagnetic suction cups at both ends and the corresponding ends of the steel plate is the same, to ensure that the steel plate is subjected to the same adsorption force by the electromagnetic crane per unit area.

[0016] In step 1, let the thickness of the steel plate being lifted be l3. The electromagnetic crane adjusts its voltage V according to the thickness l3 of the steel plate, so that the maximum number of steel plates n lifted by the electromagnetic crane in a single operation satisfies 2≤n≤5.

[0017] In step 2, when the electromagnetic crane is in the state of adsorbing n steel plates, if the operator presses the electromagnetic crane power off button and keeps it pressed without stopping, the time interval t1 between the bottom steel plates falling in sequence will satisfy t1>1s.

[0018] When the time interval t1 between the falling steel plates at the bottom layer all satisfy t1 > 2.5s, in step 2B, if the target steel plate is not at the bottom layer of the steel plates being held by the electromagnetic crane, adjust the height of the electromagnetic crane holding the steel plate so that the distance between the bottom surface of the bottom layer of the steel plate held by the electromagnetic crane and the top surface of the top layer of the steel plate in the storage pile is h. At this time, the operator presses the electromagnetic crane power off button and keeps it pressed, the electromagnetic crane suction cup stops supplying power, and the steel plates at the bottom layer fall sequentially above the steel plate storage pile. When the target steel plate is at the bottom layer of the steel plates being held by the electromagnetic crane, the operator releases the electromagnetic crane power off button, the electromagnetic crane suction cup resumes power supply, and then step 2A is performed to complete the lifting of the target steel plate.

[0019] In step 2, the distance h between the bottom surface of the lowest layer of steel plate adsorbed by the electromagnetic crane and the top surface of the highest layer of steel plate in the stack of steel plates should satisfy l3≤h≤2l3.

[0020] The present invention has the following beneficial effects:

[0021] 1. This invention enables the electromagnetic crane to lower multiple steel plates one by one through the single-plate release function of the crane's electromagnetic chuck while ensuring that the working voltage of the electromagnetic crane remains constant during a single hoisting operation. This allows the target steel plate to be located at the lowest layer of the electromagnetic crane's adsorption, thus completing the single-plate rapid hoisting operation. Attached Figure Description

[0022] Figure 1 This is a simplified diagram of the control method for the single-sheet release function of the electromagnetic crane steel plate in the present invention. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0024] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0025] A control method based on the single-sheet release function of an overhead crane electromagnetic hoist includes the following steps:

[0026] Step 1: Pre-treatment of the target steel plate before single-sheet release: The electromagnetic crane includes an electromagnetic crane base and electromagnetic suction cups. Several electromagnetic suction cups are parallel to each other and evenly distributed at the same intervals below the electromagnetic crane base. Typically, steel plates of the same length and thickness but different numbers are vertically stacked in the workshop's steel plate storage pile to facilitate subsequent steel plate lifting operations. Therefore, the pre-treatment of the target steel plate before single-sheet release by the electromagnetic crane specifically includes the following steps:

[0027] Step 1A: Set the working voltage V of the electromagnetic crane and turn on several adjacent electromagnetic chucks to ensure that the electromagnetic chucks can perform a concentrated adsorption effect on the steel plate. The change of the working voltage V can control the adsorption force of the same electromagnetic chuck. In this embodiment, it is mainly for the lifting work when the working voltage V is constant.

[0028] In this embodiment, let the length of the steel plate being lifted be l1. The electromagnetic crane preferably opens several adjacent electromagnetic suction cups according to the length l1 of the steel plate. The distance between the electromagnetic suction cups that are opened and located at the edges of both ends is l2. l2 should satisfy: 1m < l1 - l2 < 2m, and the distance between the electromagnetic suction cups at both ends and the corresponding ends of the steel plate is the same, thereby ensuring that the steel plate is subjected to the same adsorption force by the electromagnetic crane per unit area.

[0029] Step 1B: Determine the layer number m of the steel plate storage stack where the steel plate to be hoisted is located. Move the electromagnetic crane vertically above the steel plate storage stack, lower the electromagnetic crane until the bottom of the electromagnetic crane suction cup is completely in contact with the steel plate at the top of the storage stack, then raise the electromagnetic crane so that the operator can confirm the number n of steel plates held by the electromagnetic crane at this time. n is the thickness of the current steel plate, corresponding to the maximum number of steel plates that the electromagnetic crane can hoist in a single operation. Let the thickness of the steel plate to be hoisted be l3. In this embodiment, the electromagnetic crane voltage V should be adjusted according to the steel plate thickness l3 so that the maximum number of steel plates n that the electromagnetic crane can hoist in a single operation is within the set range of 3≤n≤4, ensuring that the operator can confirm the hoisting status of the steel plate while the number of steel plates hoisted in a single operation meets the condition for releasing a single steel plate.

[0030] Because the steel plate retains a significant magnetic force during demagnetization, and this force gradually weakens and eventually disappears over time, this embodiment uses an electromagnetic crane to demagnetize a 6mm steel plate. The demagnetization time is approximately 25 seconds. Based on the characteristic that the steel plate retains magnetic force after demagnetization, the output of the working electromagnet can be blocked when its magnetic force is strong. At this time, the three-phase positive rectifier circuit stops working, and the DC current flowing to the electromagnet disappears instantaneously. The electromagnet's magnetic force will then be reduced to about 1 / 2 to 1 / 3 of its original value. Therefore, the steel plate at the bottom of the electromagnet will fall to its storage position first due to the gradually weakening magnetic force. At this point, the DC current in the rectifier circuit should be restored to normal voltage immediately after a momentary deflection to zero. The remaining steel plate on the electromagnet will then be firmly held in place, thus achieving the goal of releasing only one steel plate.

[0031] like Figure 1 As shown, in this embodiment, the single-sheet release function is mainly controlled by buttons in the control room. The output signal is preferably directly connected to the S7-200 PLC input point. The PLC input point controls the power-off delay command, which calls the interrupt program and blocks the pulse output. The blocking time should not be too long, and is adjusted to approximately 3 seconds based on the strength of the electromagnetic chuck's magnetic force, mainly adjusted according to the electromagnet's residual magnetism. By blocking the pulse, the electromagnet voltage momentarily drops to zero before returning to normal. The voltage detection circuit and alarm circuit require short-term processing, approximately 1 second, to ensure the rectifier circuit operates normally.

[0032] Step 1C: When m≤n, the target steel plate and the upper layer steel plate can be hoisted together in one go, thus completing the pre-treatment of the target steel plate before single-sheet release; when x×n<m≤(x+1)×n, where x≥2, the adsorbed steel plate is hoisted to the remaining steel plate storage area, and the adsorption and hoisting of steel plates to the remaining steel plate storage area is repeated x times, with each adsorption of n steel plates, keeping the number of layers containing the target steel plate within the range of the number of steel plates that can be hoisted in a single go. At this time, the electromagnetic crane is operated again to run to the steel plate storage area and adsorb n steel plates, the electromagnetic crane is raised so that the operator can confirm the number of steel plates adsorbed by the electromagnetic crane at this time, thus completing the pre-treatment of the target steel plate before single-sheet release.

[0033] Step 2: Lifting the target steel plate. The working procedure is determined based on the different positions of the target steel plate when it is attracted, specifically including the following steps:

[0034] Step 2A: When the target steel plate is at the bottom layer of the electromagnetic crane's suction cups, control the electromagnetic crane to move vertically above the target steel plate storage area. Lower the electromagnetic crane to a distance h between the bottom surface of the target steel plate and the storage area. The distance h between the bottom surface of the bottom layer of the electromagnetic crane and the top surface of the top layer of the storage stack should satisfy l3 ≤ h ≤ 2l3 to ensure that the released steel plate can fall smoothly to the target area without being affected by the suction force of the electromagnetic crane. The operator should press and hold the electromagnetic crane power-off button to stop the power supply to the electromagnetic crane suction cup. When the target steel plate begins to fall relative to the storage area, the operator should release the electromagnetic crane power-off button in time, the electromagnetic crane suction cup will be restored to power, the electromagnetic crane will rise, and the remaining steel plate will be lifted to the storage stack, thus completing the lifting operation of the target steel plate.

[0035] In this embodiment, when the electromagnetic crane is in the state of adsorbing n steel plates, if the operator presses the electromagnetic crane power off button and keeps it pressed without stopping, the time interval t1 between the bottom steel plates falling in sequence should all satisfy t1>1s. This ensures that the operator can clearly identify the falling situation of the steel plates and release the electromagnetic crane power off button in time, so that the electromagnetic crane suction cup can be restored to power supply, preventing excess steel plates from falling together.

[0036] Step 2B: When the target steel plate is not at the bottom layer of the electromagnetic crane, adjust the height of the electromagnetic crane so that the distance between the bottom surface of the bottom layer of the electromagnetic crane and the top surface of the top layer of the steel plate in the stack is h. At this time, the operator presses the electromagnetic crane power off button and keeps it pressed. The electromagnetic crane suction cup stops supplying power. When the bottom layer of the steel plate begins to fall relative to the stack of steel plates, the operator releases the electromagnetic crane power off button, and the electromagnetic crane suction cup resumes power supply.

[0037] Step 2C: Determine whether the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate. If the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate, perform step 2A to complete the lifting of the target steel plate. If the target steel plate is not at the bottom layer of the electromagnetic crane's adsorption plate, repeat step 2B until the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate, then perform step 2A to complete the lifting of the target steel plate.

[0038] Step 2C is mainly used to gradually determine whether the target steel plate is at the bottom layer of the electromagnetic crane's suction cups, so as to release the target steel plate to the target area. At this time, the operator needs to continuously press the power-off button to release the plate. When the time interval t1 between the steel plates at the bottom layer falling one by one all meet the condition t1>2s, the time interval for the operator to confirm the falling status of the steel plate is further increased. Therefore, the operation of step 2B can be adjusted. The specific operation steps are as follows: When the target steel plate is not at the bottom layer of the electromagnetic crane's suction cups, adjust the height of the electromagnetic crane to make the distance between the bottom surface of the bottom layer of the electromagnetic crane's suction cups and the top surface of the top layer of the steel plate stack h. At this time, the operator presses the electromagnetic crane's power-off button and keeps it pressed. The electromagnetic crane suction cup stops supplying power, and the steel plates at the bottom layer fall one by one to the top of the steel plate stack. When the target steel plate is at the bottom layer of the electromagnetic crane's suction cups, the operator releases the electromagnetic crane's power-off button, the electromagnetic crane suction cup resumes power supply, and then the operation of step 2A is performed to complete the lifting of the target steel plate.

[0039] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A control method based on the single-sheet release function of an electromagnetic crane lifting steel plate, characterized in that, Includes the following steps: Step 1: Pre-treatment of the target steel plate before single-sheet release: The electromagnetic crane includes an electromagnetic crane base and electromagnetic crane suction cups. Several electromagnetic crane suction cups are parallel to each other and evenly distributed at the same intervals below the electromagnetic crane base. The steel plate storage stack contains several steel plates of the same length and thickness but different numbers. The pre-treatment of the target steel plate by the electromagnetic crane before single-sheet release specifically includes the following steps: Step 1A: Set the working voltage V of the electromagnetic crane and turn on several adjacent electromagnetic crane suction cups; Step 1B: Determine the number m of the steel plate stack where the steel plate being hoisted is located. Move the electromagnetic crane to a position directly above the steel plate stack. Lower the electromagnetic crane until the bottom of the electromagnetic crane suction cup is completely in contact with the steel plate at the top of the steel plate stack. Then raise the electromagnetic crane so that the operator can confirm the number n of steel plates that the electromagnetic crane is holding at this time. n is the thickness of the current steel plate, which corresponds to the maximum number of steel plates that the electromagnetic crane can hoist in a single operation. Step 1C: When m≤n, the pre-processing of the target steel plate before single-sheet release is completed; When x×n<m≤(x+1)×n, where x≥2, the adsorbed steel plate is hoisted to the remaining steel plate storage area, and the adsorption of steel plates is repeated and hoisted to the remaining steel plate storage area x times. The number of steel plates adsorbed each time is n. At this time, the electromagnetic crane is operated again to run to the steel plate storage area and adsorb n steel plates. The electromagnetic crane is raised so that the operator can confirm the number of steel plates adsorbed by the electromagnetic crane at this time, and the pre-treatment of the target steel plate before single release is completed. Step 2, hoisting the target steel plate, specifically includes the following steps: Step 2A: When the target steel plate is at the bottom layer of the electromagnetic crane, control the electromagnetic crane to move vertically above the target steel plate storage area, and lower the electromagnetic crane to a distance h between the bottom surface of the target steel plate and the target steel plate storage area. At this time, the operator presses the electromagnetic crane power off button and keeps it pressed. The electromagnetic crane suction cup stops supplying power. When the target steel plate begins to fall relative to the target steel plate storage area, the operator releases the electromagnetic crane power off button. The electromagnetic crane suction cup resumes power supply, raises the electromagnetic crane, and lifts the remaining steel plate to the steel plate storage stack, completing the lifting work of the target steel plate. Step 2B: When the target steel plate is not located at the bottom layer of the electromagnetic crane, adjust the height of the electromagnetic crane so that the distance between the bottom surface of the bottom layer of the electromagnetic crane and the top surface of the top layer of the steel plate in the stack is h. At this time, the operator presses the electromagnetic crane power off button and keeps it pressed. The electromagnetic crane suction cup stops supplying power. When the bottom layer of the steel plate begins to fall relative to the stack of steel plates, the operator releases the electromagnetic crane power off button and the electromagnetic crane suction cup resumes power supply. Step 2C: Determine whether the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate. If the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate, perform step 2A to complete the lifting of the target steel plate. If the target steel plate is not at the bottom layer of the electromagnetic crane's adsorption plate, repeat step 2B until the target steel plate is at the bottom layer of the electromagnetic crane's adsorption plate, then perform step 2A to complete the lifting of the target steel plate.

2. The control method based on the single-sheet release function of the overhead crane electromagnetic hoist according to claim 1, characterized in that: In step 1A, let the length of the steel plate being lifted be l1. The electromagnetic crane opens several adjacent electromagnetic suction cups according to the length l1 of the steel plate. The distance between the electromagnetic suction cups that are opened and located at the two ends is l2. l2 should satisfy: 1m < l1 - l2 < 2m, and the distance between the electromagnetic suction cups at both ends and the corresponding ends of the steel plate is the same, to ensure that the steel plate is subjected to the same adsorption force by the electromagnetic crane per unit area.

3. The control method based on the single-sheet release function of the overhead crane electromagnetic hoist according to claim 1, characterized in that: In step 1, let the thickness of the steel plate being lifted be l3. The electromagnetic crane adjusts its voltage V according to the thickness l3 of the steel plate, so that the maximum number of steel plates n lifted by the electromagnetic crane in a single operation satisfies 3≤n≤4.

4. The control method based on the single-sheet release function of the overhead crane electromagnetic hoist according to claim 1, characterized in that: In step 2, when the electromagnetic crane is in the state of adsorbing n steel plates, if the operator presses the electromagnetic crane power off button and keeps it pressed without stopping, the time interval t1 between the bottom steel plates falling in sequence will satisfy t1>1s.

5. The control method based on the single-sheet release function of the overhead crane electromagnetic hoist according to claim 4, characterized in that: When the time interval t1 between the falling steel plates at the bottom layer all satisfy t1 > 2.5s, in step 2B, if the target steel plate is not at the bottom layer of the steel plates being held by the electromagnetic crane, adjust the height of the electromagnetic crane holding the steel plate so that the distance between the bottom surface of the bottom layer of the steel plate held by the electromagnetic crane and the top surface of the top layer of the steel plate in the storage pile is h. At this time, the operator presses the electromagnetic crane power off button and keeps it pressed, the electromagnetic crane suction cup stops supplying power, and the steel plates at the bottom layer fall sequentially above the steel plate storage pile. When the target steel plate is at the bottom layer of the steel plates being held by the electromagnetic crane, the operator releases the electromagnetic crane power off button, the electromagnetic crane suction cup resumes power supply, and then step 2A is performed to complete the lifting of the target steel plate.

6. The control method based on the single-sheet release function of the overhead crane electromagnetic hoist according to claim 3, characterized in that: In step 2, the distance h between the bottom surface of the lowest layer of steel plate adsorbed by the electromagnetic crane and the top surface of the highest layer of steel plate in the stack of steel plates should satisfy l3≤h≤2l3.

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