Safety device for lifting mechanism and cutting machine

Abstract

To provide a highly safe safety device for lifting means that detects an abnormal motion of a lifting object when a malfunction or erroneous operation occurs in the lifting means, and stops the lifting object.SOLUTION: A safety device 30 for lifting means 20 that lifts a cutting torch 11 in the vertical direction, includes: a linear guide 31 which extends in the lifting direction; a linear brake 33 which travels on the linear guide with the cutting torch and can stop the cutting torch on the linear guide; a distance sensor 34 which measures a distance to the lifting object; a control unit 35 which determines whether there is a discrepancy between a commanded motion of the lifting means based on an operation signal input to operate the lifting means and an actual motion of the cutting torch based on the distance measured by the distance sensor. The control unit activates the linear brake regardless of the operation signal when there is a discrepancy between the commanded motion and the actual motion.SELECTED DRAWING: Figure 3

Description

Technical Field

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[0001] The present invention relates to a safety device for lifting means and a fuse.

Background Art

[0002] Conventionally, lifting means for moving a lifting object upward or downward is provided with a fall prevention device that prevents the lifting object from falling when a malfunction or malfunction occurs. For example, Patent Document 1 proposes an emergency brake device that detects the speed of a rope by a sensor and automatically applies a brake when the moving speed exceeds an allowable value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, such a brake device can prevent the lifting object from falling, but cannot prevent other abnormal operations due to malfunctions or malfunctions of the lifting means, and the safety is insufficient.

[0005] Further, as another lifting means, there is one that uses a ball screw composed of a rotatable screw shaft and a nut screwed onto the screw shaft, and raises and lowers the nut by rotating the screw shaft by a drive motor. When such a ball screw is used for the lifting means, if the screw shaft is damaged or the like, the lifting object may suddenly drop, and there is a problem with safety.

[0006] The present invention has been made in view of such points, and an object thereof is to provide a safety device for lifting means that detects an abnormal operation of a lifting object when a malfunction or malfunction occurs in the lifting means and stops the lifting object. [Means for solving the problem]

[0007] To achieve the above objective, the present invention is equipped with a distance sensor that measures the distance to the object to be raised or lowered, and makes it possible to determine whether there is any inconsistency between the actual operation based on the distance sensor and the command operation based on the operation signal.

[0008] Specifically, the first invention relates to a safety device for a lifting mechanism that raises and lowers an object in the vertical direction. A linear guide extending in the vertical direction, A linear brake that travels along the linear guide with the object to be raised and lowered, and that can stop the object to be raised and lowered on the linear guide, A distance sensor for measuring the distance to the object to be raised or lowered, The system includes a control unit that determines whether there is any discrepancy between the command operation of the lifting object based on the operation signal input to operate the lifting object and the actual operation of the lifting object based on the distance measured by the distance sensor. The control unit is characterized in that, if there is a discrepancy between the command operation and the actual operation, it will activate the linear brake regardless of the operation signal.

[0009] According to the first invention, the control unit determines whether the object being lifted is performing the commanded operation based on the operation signal by comparing the movement of the object based on the distance measured by the distance sensor with the commanded operation. This configuration allows the control unit to monitor whether the object is performing an operation that contradicts the commanded operation, and if it determines that an operation has contradicted the command, it can immediately stop that operation. This not only prevents the object from falling but also detects and stops other abnormal movements, thus ensuring a high level of safety for workers and the object being lifted. Furthermore, if this safety device is applied to a conventional lifting mechanism using a ball screw, even if the screw shaft breaks, the object being lifted will be stopped and held on the linear guide by the linear brake, thus preventing a sudden fall.

[0010] In the second invention, in the first invention, The control unit is characterized by determining whether the distance measured by the distance sensor and the direction of movement of the object to be raised or lowered, calculated based on that distance, are inconsistent with the command operation.

[0011] According to the second invention, it is possible to detect not only abnormal movement in the downward direction of the object being lifted, but also abnormal movement in the upward direction, thereby ensuring a higher level of safety.

[0012] In the third invention, in the first invention, Equipped with multiple distance sensors, The control unit is characterized in that, if there is a discrepancy between the actual operation of the lifting / lowering object based on the distance detected by any one of the distance sensors and the commanded operation, it causes the discrepant distance sensor to remeasure the distance.

[0013] According to the third invention, safety is further enhanced by providing multiple distance sensors, but the distance sensors may malfunction immediately after switching operations or due to vibrations and shocks. Therefore, by requiring remeasurement for conflicting distance sensors, it is possible to prevent the lifting mechanism from stopping due to distance sensor malfunctions, thereby ensuring safety and preventing a decrease in work efficiency.

[0014] In the fourth invention, in the third invention, The control unit is characterized in that, if it detects a downward movement exceeding a predetermined threshold based on the distance detected by any one of the distance sensors, it activates the linear brake and stops the object being raised or lowered, prioritizing this over re-measurement.

[0015] According to the fourth invention, if the discrepancy in the distance sensor is not due to a malfunction, requiring a remeasurement may delay the abnormality detection by the control unit. However, if the system is configured to activate the linear brake in priority over remeasurement when a downward movement exceeding a predetermined threshold is detected, it becomes possible to achieve both work efficiency and safety.

[0016] The fifth invention relates to a cutting machine equipped with a safety device for the lifting and lowering means according to any one of claims 1 to 4, wherein the object to be lifted and lowered is a cutting machine main body having a cutting torch for cutting a cutting object by heat.

[0017] Since a cutting machine for cutting metal or the like raises and lowers a cutting torch that ejects a combustible gas, an abnormal operation of its lifting and lowering means involves a greater risk compared to a lifting and lowering device that simply raises and lowers a load or the like. Therefore, according to the fifth invention, it is particularly significant to apply the first to fourth inventions, which can immediately detect an abnormality in the upward or downward movement of the object to be lifted and lowered and ensure high safety, to a cutting machine.

Advantages of the Invention

[0018] As described above, according to the present invention, it is possible to provide a highly safe safety device for a lifting and lowering means that detects and stops an abnormal operation of the object to be lifted and lowered when a malfunction or malfunction occurs in the lifting and lowering means.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram of a cutting machine equipped with the safety device according to this embodiment. [Figure 2] It is a diagram showing an operation signal and a determination by a control unit. [Figure 3] It is a flowchart showing a determination and processing by a control unit.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described based on the drawings. Note that the following description of the preferred embodiments is merely illustrative and is not intended to limit the present invention, its applications, or its uses.

[0021] (Configuration of the cutting machine) As shown in Figure 1, the cutting machine of this embodiment comprises a cutting machine body 10, a lifting mechanism 20, and a safety device 30 for the lifting mechanism 20. The cutting machine body 10 comprises a cutting torch 11, a telescopic arm 12 with the cutting torch 11 attached to its tip, a lifting base 13, and a holding part 14. The cutting machine body 10 performs cutting work on large slags, waste materials, etc., by burning flammable gas sprayed from the cutting torch 11. The object to which the lifting mechanism 20 moves is the cutting machine body 10. The cutting machine body 10 can move the cutting torch 11 in the vertical direction by the lifting mechanism 20.

[0022] The cutting torch 11 is provided at one end of the telescopic arm 12. The cutting torch 11 is equipped with a blowpipe 11a at its tip that can blow out oxygen and flammable gas to cause combustion. The blowpipe 11a opens downwards. The telescopic arm 12 moves the cutting torch 11 by extending and retracting horizontally.

[0023] The lifting base 13 is provided at the other end of the telescopic arm 12. The lifting base 13 is connected to the lifting mechanism 20 via a ball nut 22. The holding part 14 is provided between the lifting base 13 and the telescopic arm 12. The holding part 14 is connected to the linear bearing 32 and linear brake 33 of the safety device 30.

[0024] The lifting mechanism 20 is a ball screw that raises and lowers the cutting machine body 10 in the vertical direction. The lifting mechanism 20 has a screw shaft 21, a ball nut 22, and a motor (not shown). The ball nut 22 is inserted through the screw shaft 21, and the screw shaft 21 is rotationally driven by the motor. As the screw shaft 21 is rotationally driven, the cutting torch 11, which is connected to the lifting mechanism 20 via the ball nut 22, moves up and down.

[0025] The extension and retraction of the telescopic arm 12 and the raising and lowering of the lifting mechanism 20 are performed by an operator operating the control panel 40. When the operator inputs the desired operation using the control panel 40, an operation signal is input to the telescopic arm 12 and the lifting mechanism 20 via the control unit 35, and the telescopic arm 12 and the lifting mechanism 20 operate according to the operation command based on that operation signal. The input of the operation signal is not limited to operation of the control panel by an operator; for example, it may be based on a program.

[0026] (Configuration of safety devices) The safety device 30 is a safety device for the lifting means 20. The safety device 30 comprises a linear guide 31, a linear bearing 32, a linear brake 33, a distance sensor 34, a control unit 35, a limit switch 38, and a solenoid valve 36 and a compressor 37 for driving the linear brake 33.

[0027] The linear guide 31 is a rail-shaped member with a rectangular cross-section and extends in the vertical direction. In this embodiment, a pair of linear guides 31 are provided with a gap between them on the left and right sides. The linear bearings 32 are movable along the linear guides 31 in the vertical direction. Two linear bearings 32 are provided on each linear guide 31 with a gap between them vertically. A linear brake 33 is provided between the vertically aligned linear bearings 32, 32. The linear brake 33 is movable along the linear guides 31 in the vertical direction. The telescopic arm 12 is connected to the safety device 30 via the linear bearings 32 and the linear brake 33.

[0028] The linear brake 33 travels along the linear guide 31 together with the holding part 14 of the cutting machine body 10, and can stop and hold the holding part 14 on the linear guide 31. The linear brake 33 is formed to straddle the linear guide 31 and is a normally closed type that clamps the linear guide 31 when no external force is applied. The linear brake 33 may be driven by any means, but in this embodiment it is driven by pneumatics. A solenoid valve 36 and a compressor 37 are connected to the linear brake 33. The solenoid valve 36 controls the high-pressure air from the compressor 37 under the control of a control unit 35, which will be described later. When high-pressure air from the compressor 37 is supplied to the linear brake 33, the clamp of the linear brake 33 is released, and the telescopic arm 12 becomes able to move up and down. When high-pressure air is not supplied to the linear brake 33, the linear brake 33 is clamped, and the telescopic arm 12 is stopped and held on the linear guide 31.

[0029] A distance sensor 34 is provided at the upper or lower end of the linear guide 31, and a limit switch 38 is provided at the lower end.

[0030] The distance sensor 34 measures the distance to the holding part 14 in the vertical direction. The distance sensor 34 is mounted on the linear guide 31. In this embodiment, the distance sensor 34 is mounted at the upper end of the linear guide 31 and measures the distance to the holding part 14. The numerical value measured by the distance sensor 34 is input to the control unit 35.

[0031] It is preferable that multiple distance sensors 34 are provided. In this embodiment, each of the two linear guides 31, 31 is equipped with a distance sensor 34, and each distance sensor 34 performs measurement independently and inputs the numerical value to the control unit 35.

[0032] The control unit 35 can calculate the actual operation of the cutting machine body 10, such as whether it is moving upward or downward, and at what speed the cutting machine body 10 is moving upward or downward, based on the distance measured by the distance sensor 34. The control unit 35 compares the command operation of the lifting / lowering means 20, based on the operation signals input to operate the lifting / lowering means 20, with the actual operation of the cutting machine body 10, based on the distance measured by the distance sensor 34, and determines whether there is any inconsistency between the command operation and the actual operation. The operation signals input to operate the lifting / lowering means 20 are, for example, operation signals input by an operator using the control panel 40 or operation signals from a program, and are operation signals for upward or downward movement.

[0033] The control unit 35 can activate the linear brake regardless of the operation signal if there is a discrepancy between the commanded operation and the actual operation. In this case, "activation" refers to the state in which high-pressure air is not supplied to the linear brake 33 and the linear brake 33 is clamped. When the linear brake 33 is activated, the telescopic arm 12 is held on the linear guide 31.

[0034] Figure 2 shows the determination made by the control unit 35 when comparing the commanded operation based on the operation signal with the actual operation calculated based on the distance measured by the distance sensor 34. For example, if the control unit 35 determines that the cutting machine body 10 is descending despite the operation signal indicating an upward movement, based on the information measured by the distance sensor 34, it determines that the direction of movement is abnormal and activates the linear brake 33 to stop the upward or downward movement. Also, for example, if the control unit 35 determines that the distance of upward movement due to the operation signal does not match the distance measured by the distance sensor 34, it determines that the distance is abnormal and activates the linear brake 33 to stop the upward or downward movement.

[0035] If multiple distance sensors 34, 34 are provided, the control unit 35 will cause the conflicting distance sensor 34 to remeasure the distance if there is a discrepancy between the actual operation of the cutting machine body 10 based on the distance detected by any one of the distance sensors 34 and the commanded operation. If the control unit 35 detects a downward movement exceeding a predetermined threshold based on the distance detected by any one of the distance sensors 34, it will activate the linear brake 33 and stop the cutting machine body 10, taking priority over remeasurement. In this embodiment, there are two distance sensors 34(A) and distance sensor 34(B), but there may be three or more distance sensors 34.

[0036] (Determination and processing by the control unit) Next, the determination and processing by the control unit 35 will be explained based on Figure 3. When the operation signal is turned ON, for example, in step S100, the control unit 35 determines whether the downward distance has been exceeded based on the information measured by one of the distance sensors A. If the distance measured by distance sensor A exceeds the distance of the operation signal and it is determined that the actual operation contradicts the command operation (Yes), and in step S101, the control unit 35 determines whether the downward distance has been exceeded based on the information measured by the other distance sensor B, and it is determined that the distance measured by distance sensor B does not exceed the distance of the operation signal and that the actual operation does not contradict the command operation (No), then in step S102, the control unit 35 causes the inconsistent distance sensor A to be remeasured. In step 103, if the result of the remeasurement determines that the distance measured by distance sensor A exceeds the distance of the operation signal and that the actual operation contradicts the command operation (Yes), the control unit 35 activates the linear brake and performs an emergency stop regardless of the operation signal. If the remeasurement in step S102 determines in step S103 that the actual operation does not contradict the commanded operation (No), the process returns to START, the determination is repeated, and the lifting and lowering operation continues.

[0037] As another example, in step S100, if the control unit 35 determines that the distance measured by distance sensor A does not exceed the distance of the operation signal and that the actual operation does not contradict the command operation (No), then in step S110, it determines whether the distance on the downward side has been exceeded based on the information measured by the other distance sensor B. If the distance measured by distance sensor B exceeds the distance of the operation signal and it is determined that the actual operation contradicts the command operation (Yes), then in step S111, it causes the inconsistent distance sensor B to be remeasured. In step 112, if the remeasurement results in the distance measured by distance sensor B exceeding the distance of the operation signal and it is determined again that the actual operation contradicts the command operation (Yes), the linear brake is activated regardless of the operation signal, and an emergency stop is performed. If the remeasurement in step 111 results in the determination in step S112 that the actual operation does not contradict the command operation (No), the unit returns to START and repeats the determination, continuing the lifting and lowering operation.

[0038] As another example, in step S100, the control unit 35 determines whether the downward distance has been exceeded based on the information measured by one of the distance sensors A. If the distance measured by distance sensor A exceeds the distance of the operation signal and it is determined that the actual operation contradicts the command operation (Yes), and in step S101, the control unit 35 determines whether the downward distance has been exceeded based on the information measured by the other distance sensor B, and it is determined that the distance measured by distance sensor B exceeds the distance of the operation signal and that the actual operation contradicts the command operation (Yes), then the linear brake is activated regardless of the operation signal to bring the train to an emergency stop.

[0039] Furthermore, as another example, even if distance sensors A and B do not exceed the distance limit, if the control unit 35 detects any other abnormality in step S120, it remeasures the other abnormality in step S121, and if the other abnormality is detected again in step 122, it activates the linear brake and performs an emergency stop regardless of the operation signal. If the remeasurement determines that the actual operation is not inconsistent with the command operation (No), it continues the lifting and lowering operation, returns to START, and repeats the determination.

[0040] Furthermore, if the control unit 35 determines that the distance exceeding a predetermined threshold, it will activate the linear brake and bring the train to an emergency stop without going through the remeasurement step.

[0041] (Effects and Benefits) According to this embodiment, the control unit 35 determines whether the object being lifted is performing the operation as commanded based on the operation signal by comparing the operation of the object based on the distance measured by the distance sensor 34 with the commanded operation. This configuration allows the control unit 35 to monitor whether the object is performing an operation that contradicts the commanded operation, and if an inconsistent operation occurs, it can immediately stop that operation. This not only prevents the object from falling but also detects and stops other abnormal operations, thus ensuring a high level of safety for workers and the object being lifted. Furthermore, if this safety device 30 is applied to a lifting means 20 using a ball screw, even if the screw shaft 21 breaks, the object being lifted will be stopped and held on the linear guide 31 by the linear brake 33, thus preventing a sudden fall.

[0042] Furthermore, by re-measuring any inconsistent distance sensors 34, it becomes possible to prevent the lifting mechanism 20 from stopping due to malfunctions of the distance sensors 34, thereby ensuring safety and preventing a decrease in work efficiency.

[0043] Furthermore, if the discrepancy in the distance sensor 34 is not due to a malfunction, requiring a remeasurement may delay the abnormality detection by the control unit 35. However, if the system is configured to activate the linear brake 33 in priority over remeasurement when a downward movement exceeding a predetermined threshold is detected, it becomes possible to achieve both work efficiency and safety. [Explanation of symbols]

[0044] 10. Cutting machine body 11 Cutting Torch 11a Blowpipe 12 Extendable Arms 13 Lifting base 14 Holding part 20 Lifting and lowering means 21 Screw shaft 22 Ball Nut 30 Safety equipment 31 Linear Guide 32 Linear bearings 33 Linear Brake 34 Distance Sensor 35 Control Unit 36 Solenoid valve 37 Compressor 40 Control panel

Claims

[Claim 1] A safety device for a lifting mechanism that raises and lowers an object to be lifted in the vertical direction, and a cutting machine body having a cutting torch that cuts an object to be cut by heat as the object to be lifted, The aforementioned safety device is A linear guide extending in the vertical direction, A linear brake that travels along the linear guide with the object to be raised and lowered, and that can stop the object to be raised and lowered on the linear guide, Multiple distance sensors for measuring the distance to the object to be raised or lowered, The system includes a control unit that determines whether there is any discrepancy between the command operation of the lifting means based on the operation signal input to operate the lifting means and the actual operation of the object being lifted based on the distance measured by the distance sensor. The control unit, If there is a discrepancy between the actual movement of the object being raised or lowered based on the distance detected by any one of the distance sensors and the commanded operation, the distance sensor with the discrepancy is instructed to remeasure the distance, and if there is still a discrepancy between the commanded operation and the actual movement after remeasurement, the linear brake is activated regardless of the operation signal. If there is a discrepancy between the actual movement of the lifting / lowering object based on the distance detected by any one of the distance sensors and the commanded movement, and if a downward movement exceeding a predetermined threshold is detected based on the distance detected by any one of the distance sensors, the linear brake is activated in priority over the remeasurement and the lifting / lowering object is stopped. A cutting machine characterized by the following features.

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