Safety device for lifting means and fusion-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

[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] In addition, 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 with a drive motor. When such a ball screw is used for lifting means, if the screw shaft breaks or the like, the lifting object may fall suddenly, 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] In order to achieve the above object, the present invention is provided with a distance sensor for measuring the distance to the object to be lifted and lowered, and it is possible to determine whether there is a contradiction 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 means for vertically lifting and lowering an object to be lifted and lowered. A linear guide extending in the lifting and lowering direction, A linear brake that travels on the linear guide together with the object to be lifted and lowered and can stop the object to be lifted and lowered on the linear guide, A distance sensor for measuring the distance to the object to be lifted and lowered, A control unit that determines whether there is a contradiction between the command operation of the object to be lifted and lowered based on the operation signal input for operating the object to be lifted and lowered and the actual operation of the object to be lifted and lowered based on the distance measured by the distance sensor, The control unit is characterized in that when there is a contradiction between the command operation and the actual operation, the linear brake is operated regardless of the operation signal.

[0009] According to the first invention, the control unit compares the operation of the object to be lifted and lowered based on the distance measured by the distance sensor with the commanded operation to determine whether the object to be lifted and lowered is performing the operation as commanded based on the operation signal. By this configuration, it is possible to monitor whether the object to be lifted and lowered is performing an operation that contradicts the command operation, and when it is determined that the object is performing a contradictory operation, the operation can be immediately stopped. Not only can the fall of the object to be lifted and lowered be prevented, but other abnormal operations can also be detected and stopped, so it is possible to ensure high safety for the operator and the object to be lifted and lowered. In addition, if this safety device is applied to the conventional lifting means using a ball screw, even when the screw shaft is broken, the object to be lifted and lowered can 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 moving direction of the object to be lifted and lowered calculated based on the distance conflict with the command operation.

[0011] According to the second invention, since it is possible to detect not only abnormal operations in the lowering direction of the object to be lifted and lowered but also abnormal operations in the rising direction, it is possible to ensure higher safety.

[0012] In the third invention, in the first invention, a plurality of the distance sensors are provided, and when there is a conflict between the actual operation of the object to be lifted and lowered based on the distance detected by any one of the distance sensors and the command operation, the control unit causes the distance sensor in conflict to re-measure the distance.

[0013] According to the third invention, by providing a plurality of distance sensors, safety is further enhanced. However, immediately after switching the operation, or due to vibration, impact, etc., the distance sensors may malfunction. Therefore, by re-measuring the conflicting distance sensors, it is possible to prevent the lifting means from stopping due to the malfunction of the distance sensors, ensuring safety and preventing a decrease in work efficiency.

[0014] In the fourth invention, in the third invention, when the control unit detects a downward movement exceeding a predetermined threshold value based on the distance detected by any one of the distance sensors, the control unit operates the linear brake prior to the re-measurement to stop the object to be lifted and lowered.

[0015] According to the fourth invention, if the conflict of the distance sensors is not due to a malfunction, re-measurement may cause a delay in the abnormal determination by the control unit. However, if the configuration is such that the linear brake is operated prior to re-measurement when a downward movement exceeding a predetermined threshold value is detected, it is possible to achieve both work efficiency and safety.

[0016] The fifth invention relates to a cutting machine provided with the safety device for the lifting means according to any one of claims 1 to 4, characterized in that the object to be lifted 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 the lifting means involves a greater risk compared to a lifting 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 ensure high safety, to a cutting machine.

Effects 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 means that detects and stops an abnormal operation of an object to be lifted when a problem or malfunction occurs in the lifting means.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to 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 Fig. 1, the cutting machine of this embodiment includes a cutting machine main body 10, a lifting means 20, and a safety device 30 for the lifting means 20. The cutting machine main body 10 includes a cutting torch 11, a telescopic arm 12 with the cutting torch 11 attached to its tip, a lifting base 13, and a holding portion 14. The cutting machine main body 10 performs cutting operations on large slags, waste materials, etc. by burning a combustible gas ejected from the cutting torch 11, for example. The object to be lifted by the lifting means 20 is the cutting machine main body 10. The cutting machine main body 10 can move the cutting torch 11 in the lifting direction by the lifting means 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 eject and burn oxygen and a combustible gas. The blowpipe 11a is open downward. The telescopic arm 12 moves the cutting torch 11 by expanding and contracting in the horizontal direction.

[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 means 20 via a ball nut 22. The holding portion 14 is provided between the lifting base 13 and the telescopic arm 12. The holding portion 14 is connected to the linear bearing 32 and the linear brake 33 of the safety device 30.

[0024] The lifting means 20 is a ball screw for lifting the cutting machine main body 10 in the vertical direction. The lifting means 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. When the screw shaft 21 is rotationally driven, the cutting torch 11 connected to the lifting means 20 via the ball nut 22 performs a lifting operation.

[0025] The telescoping operation of the telescoping arm 12 and the elevating operation of the elevating means 20 are performed by an operator operating the operation panel 40. When the operator inputs a target operation using the operation panel 40, an operation signal is input to the telescoping arm 12 and the elevating means 20 via the control unit 35, and the telescoping arm 12 and the elevating means 20 operate according to the operation command based on the operation signal. The input of the operation signal is not limited to the operation of the operation panel by the operator, and may be based on a program, for example.

[0026] (Configuration of safety device) The safety device 30 is a safety device for the elevating means 20. The safety device 30 includes 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 for driving the linear brake 33 and a compressor 37.

[0027] The linear guide 31 is a rail-shaped member with a rectangular cross-section and extends in the elevating direction. In the present embodiment, a pair of linear guides 31 are provided at intervals in the left-right direction. The linear bearing 32 is capable of traveling in the elevating direction along the linear guide 31. Two linear bearings 32 are provided at intervals in the vertical direction on each linear guide 31. A linear brake 33 is provided between the vertically arranged linear bearings 32, 32. The linear brake 33 is movable in the elevating direction along the linear guide 31. The telescoping arm 12 is connected to the safety device 30 via the linear bearing 32 and the linear brake 33.

[0028] The linear brake 33 travels on the linear guide 31 together with the holding part 14 of the fuse body 10, and can stop and hold the holding part 14 on the linear guide 31. The linear brake 33 is formed so as to straddle the linear guide 31, and is of a normally closed type that clamps the linear guide 31 in a normal state where no external force is applied. The linear brake 33 may be driven by any means, but in this embodiment, it is driven by pneumatic pressure. An electromagnetic valve 36 and a compressor 37 are connected to the linear brake 33. The electromagnetic valve 36 controls the high-pressure air from the compressor 37 by the control of a control unit 35 described later. When the high-pressure air from the compressor 37 is supplied to the linear brake 33, the clamping of the linear brake 33 is released, and the telescopic arm 12 can move up and down. In the normal state where no high-pressure air is 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 end or the lower end of the linear guide 31, and a limit switch 38 is provided at the lower part.

[0030] The distance sensor 34 measures the distance to the holding part 14 in the lifting direction. The distance sensor 34 is provided on the linear guide 31. In this embodiment, the distance sensor 34 is provided 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] Preferably, a plurality of distance sensors 34 are provided. In this embodiment, the two linear guides 31, 31 are each provided with a distance sensor 34, and each distance sensor 34 performs measurement independently and inputs the numerical value to the control unit 35 respectively.

[0032] Based on the distance measured by the distance sensor 34, the control unit 35 can calculate the actual operation of the fusing machine body 10, such as whether the fusing machine body 10 is moving up or down and at what speed it is moving up and down. The control unit 35 compares the commanded operation of the lifting means 20 based on the operation signal input to operate the lifting means 20 with the actual operation of the fusing machine body 10 based on the distance measured by the distance sensor 34, and determines whether there is a contradiction between the commanded operation and the actual operation. The operation signal input to operate the lifting means 20 is, for example, an operation signal input by an operator using the operation panel 40 or an operation signal by a program, and is an operation signal for rising or falling.

[0033] When there is a contradiction between the commanded operation and the actual operation, the control unit 35 can activate the linear brake regardless of the operation signal. In this case, "activation" means a 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] FIG. 2 shows the determination of the control unit 35 that compares the commanded operation by the operation signal with the actual operation calculated based on the distance measured by the distance sensor 34. For example, when the control unit 35 determines that the fusing machine body 10 is descending based on the information measured by the distance sensor 34 even though the operation signal indicates rising, it determines that the operation direction is abnormal, activates the linear brake 33, and stops the lifting operation. Also, for example, when the control unit 35 determines that the distance of the upward movement by the operation signal does not match the distance measured by the distance sensor 34, it determines that the distance is abnormal, activates the linear brake 33, and stops the lifting operation.

[0035] When a plurality of distance sensors 34, 34 are provided, if there is a contradiction between the actual operation of the fuse machine body 10 based on the distance detected by any one of the distance sensors 34 and the commanded operation, the control unit 35 causes the distance sensor 34 in contradiction to re-measure the distance. When the control unit 35 detects a downward movement exceeding a predetermined threshold value based on the distance detected by any one of the distance sensors 34, it operates the linear brake 33 preferentially over re-measurement to stop the fuse machine body 10. In the present embodiment, two left and right distance sensors 34(A) and a distance sensor 34(B) are provided, but three or more distance sensors 34 may be provided.

[0036] (Determination and processing by the control unit) Next, based on FIG. 3, the determination and processing by the control unit 35 will be described. When the operation signal becomes ON, for example, in step S100, the control unit 35 determines an excessive distance on the downward side from the information measured by one of the distance sensors A. When it is determined that the distance measured by the distance sensor A exceeds the distance of the operation signal and the actual operation contradicts the commanded operation (Yes), and in step S101, it is determined that there is an excessive distance on the downward side from the information measured by the other distance sensor B, and the distance measured by the distance sensor B does not exceed the distance of the operation signal and the actual operation does not contradict the commanded operation (No), then in step S102, the conflicting distance sensor A is re-measured. In step 103, as a result of the re-measurement, if it is determined again that the distance measured by the distance sensor A exceeds the distance of the operation signal and the actual operation contradicts the commanded operation (Yes), the linear brake is operated regardless of the operation signal to perform an emergency stop. If, as a result of the re-measurement in step S102, it is determined in step S103 that the actual operation does not contradict the commanded operation (No), the process returns to START to repeat the determination and continue the lifting operation.

[0037] Also, as another example, in step S100, when the control unit 35 determines that the distance measured by the distance sensor A does not exceed the distance of the operation signal and the actual operation does not conflict with the commanded operation (No), in step S110, it determines whether there is an excessive distance on the descending side from the information measured by the other distance sensor B. When it is determined that the distance measured by the distance sensor B exceeds the distance of the operation signal and the actual operation conflicts with the commanded operation (Yes), in step S111, the conflicting distance sensor B is re-measured. In step 112, if as a result of the re-measurement, it is again determined that the distance measured by the distance sensor B exceeds the distance of the operation signal and the actual operation conflicts with the commanded operation (Yes), the linear brake is activated regardless of the operation signal to effect an emergency stop. If as a result of the re-measurement in step 111, it is determined in step S112 that the actual operation does not conflict with the commanded operation (No), the process returns to START to repeat the determination and continue the lifting and lowering operation.

[0038] Also, as another example, in step S100, the control unit 35 determines whether there is an excessive distance on the descending side from the information measured by one of the distance sensors A. When it is determined that the distance measured by the distance sensor A exceeds the distance of the operation signal and the actual operation conflicts with the commanded operation (Yes), and in step S101, it is determined whether there is an excessive distance on the descending side from the information measured by the other distance sensor B, and when it is determined that the distance measured by the distance sensor B exceeds the distance of the operation signal and the actual operation conflicts with the commanded operation (Yes), the linear brake is activated regardless of the operation signal to effect an emergency stop.

[0039] Furthermore, as another example, even when there is no excessive distance in the distance sensors A and B, in step S120, when the control unit 35 detects other abnormalities, in step S121, the other abnormalities are re-measured, and in step 122, if the other abnormalities are re-detected, the linear brake is activated regardless of the operation signal to effect an emergency stop. If as a result of the re-measurement, it is determined that the actual operation does not conflict with the commanded operation (No), the lifting and lowering operation is continued, the process returns to START, and the determination is repeated.

[0040] In addition, when the control unit 35 determines that the distance exceeds a predetermined threshold value, it activates the linear brake and performs an emergency stop without going through the re-measurement step.

[0041] (Function and Effect) According to the present embodiment, the control unit 35 compares the operation of the lifting / lowering target based on the distance measured by the distance sensor 34 with the commanded operation to determine whether the lifting / lowering target is performing the operation as commanded based on the operation signal. By doing so, it monitors whether the lifting / lowering target is performing an operation that conflicts with the commanded operation, and if a conflicting operation occurs, it can immediately stop that operation. This not only prevents the lifting / lowering target from falling but also detects and stops other abnormal operations, thus ensuring high safety for the operator and the lifting / lowering target. Further, if this safety device 30 is applied to the lifting / lowering means 20 using a ball screw, even when the screw shaft 21 is broken, the lifting / lowering target is stopped and held on the linear guide 31 by the linear brake 33, preventing a sudden fall.

[0042] Also, by re-measuring the conflicting distance sensor 34, it is possible to prevent the lifting / lowering means 20 from stopping due to malfunction or the like of the distance sensor 34, ensuring safety and preventing a decrease in work efficiency.

[0043] Furthermore, when the conflict of the distance sensor 34 is not due to malfunction, although re-measurement may cause a delay in the abnormality determination by the control unit 35, if the configuration is such that the linear brake 33 is activated prior to re-measurement when a downward movement exceeding a predetermined threshold value is detected, it is possible to achieve both work efficiency and safety.

Explanation of Reference Numerals

[0044] 10 Fusible Machine Body 11 Cutting Torch 11a Blowpipe 12 Telescopic Arm 13 Lifting / Lowering Base 14 Holding Portion 20 Lifting / Lowering Means 21 Screw shaft 22 Ball nut 30 Safety device 31 Linear guide 32 Linear bearing 33 Linear brake 34 Distance sensor 35 Control unit 36 Solenoid valve 37 Compressor 40 Control panel

Claims

1. A safety device for a lifting means for vertically lifting and lowering an object to be lifted, comprising: a linear guide extending in the lifting direction; a linear brake that travels on the linear guide together with the object to be lifted and can stop the object to be lifted on the linear guide; a distance sensor that measures the distance to the object to be lifted; a control unit that determines whether there is a contradiction between the commanded operation of the lifting means based on an operation signal input to operate the lifting means and the actual operation of the object to be lifted based on the distance measured by the distance sensor; The safety device for a lifting means, wherein the control unit activates the linear brake regardless of the operation signal when there is a contradiction between the commanded operation and the actual operation.

2. The safety device for a lifting means according to claim 1, wherein the control unit determines whether the distance measured by the distance sensor and the moving direction of the object to be lifted calculated based on the distance are inconsistent with the commanded operation.

3. Comprising a plurality of the distance sensors, The safety device for a lifting means according to claim 1, wherein the control unit causes the distance sensor that is in contradiction to re-measure the distance when there is a contradiction between the actual operation of the object to be lifted based on the distance detected by any one of the distance sensors and the commanded operation.

4. The safety device for a lifting means according to claim 3, wherein when the control unit detects a downward movement exceeding a predetermined threshold value based on the distance detected by any one of the distance sensors, the control unit activates the linear brake prior to the re-measurement to stop the object to be lifted.

5. A welding machine comprising the safety device for a lifting means according to any one of claims 1 to 4, wherein the object to be lifted is a welding machine body having a cutting torch that cuts a cutting object by heat.

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