JPH04292389A - Drop preventing device for elevating frame - Google Patents

Abstract

PURPOSE:To prevent cutting of a suspension member, such as a wire rope, and a chain and to prevent the drop of an elevating frame. CONSTITUTION:Signal values from detecting means (load cells) 62a and 62b are compared with a preset reference value. During elevation of an elevating frame 41, and a deciding means 81 decides the presence of abnormality of a suspension member 61. When abnormality occurs to the suspension member 61, elevation of the elevating frame 41 is stopped.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a device for raising and lowering an elevating frame by winding and unwinding a hanging member such as a wire rope, and in particular, a device that prevents the elevating frame from falling by detecting abnormalities in the hanging member. Regarding prevention devices.

0002

[Prior Art] As one of the means for melting metal materials,
A melting furnace called a tower melter that extends in the vertical direction is known. When charging metal materials into this tower melter, a lifting device as shown in FIG. 9 is used. As shown in the figure, the elevating device has an elevating pedestal 1 that can be raised and lowered to convey a metal material, and the elevating pedestal 1 is suspended by a wire rope 2. A guide roller 4 that can roll along a guide rail 3 is provided on the side of the elevating frame 1 . The wire rope 2 can be wound around a drum 5, and a drive motor 6 is connected to the drum 5. By rotating the drum 5 in forward and reverse directions by the drive motor 6, the elevating platform 1 is moved up and down along the guide rail 3.

[0003] Here, if the wire rope 2 breaks due to wear or the like, the elevating platform 1 will fall, so a fall prevention pin 7 that can be moved in and out is provided on the guide rail 3 side to prevent it from falling. . However, in the case of the conventional device, since the distance over which the fall prevention pin 7 is arranged is relatively long, when the elevating platform 1 falls, the impact acting on the fall prevention pin 7 is large, and the damage to the entire device is large.

[0004] Examples of conventional techniques for preventing falling of an elevating frame etc. due to cutting of a wire rope etc. include, for example, Japanese Utility Model Application No. 151265/1983 and Japanese Utility Model Application No. 56-14.
No. 8079 and Japanese Utility Model Application No. 55-32381 are known. FIG. 10 shows a fall prevention device disclosed in Japanese Utility Model Application Publication No. 56-151265. This device is
When the hanger falls, the arm 10 is pushed in the Y direction and the stopper device 8 moves in the X direction, and due to the engagement of the stopper device 8 and the stopper pin 9a of the guide rail 9, the arm 1
0 from falling. FIG. 11 shows a safety device disclosed in Japanese Utility Model Application Publication No. 56-148079. In this device, when the wire rope 11 is cut or loosened, the locking member 13 protrudes due to the urging force of the compression spring 12, and the hook 16 is engaged with the locking member 13 and a horizontal bar 15 provided on the guide rail 14 side. The guide block 17, which is integrated with the guide block 17, is prevented from falling. FIG. 12 shows a wire rope breakage detection device disclosed in Japanese Utility Model Application Publication No. 55-32381. In this device, when the wire rope 21 is cut, the detection plate 23 provided on the rod 22 side connected to the wire rope 21 is lowered, and the detection switch 24 is operated by the lowering of the detection plate 23.

[0005]

However, in the case of any of the devices disclosed in the above-mentioned publications, it is not possible to detect an overload at the time of ascent, which may cause breakage of a hanging member such as a wire rope. Therefore, it is not possible to prevent the wire rope etc. from being cut, and the elevating frame etc. cannot be avoided from falling. As described above, in conventional equipment, the fall prevention device is activated after the wire rope, etc. is cut, so the equipment is subject to a large impact due to the fall of the lifting platform, etc., which has a large negative impact on the equipment as a whole, and cannot be repaired. It's not easy.

SUMMARY OF THE INVENTION The present invention has focused on the above-mentioned problem, and an object of the present invention is to provide a fall prevention device for an elevating frame that can prevent hanging members such as wire ropes and chains from being cut.

[0007]

[Means for Solving the Problems] A fall prevention device for an elevating pedestal according to the present invention in accordance with this object includes: a guide rail extending in the vertical direction; an elevating pedestal movable in the vertical direction along the guide rail; A chain-like or rope-shaped hanging member for suspending the lifting frame, a lifting drive means for lifting and lowering the lifting frame by winding and unwinding the hanging member, and detecting the tensile force acting on the hanging member. a detecting means for detecting, a determining means for comparing a signal value from the detecting means with a preset reference value to determine whether an abnormality has occurred in the hanging member, and based on a command signal from the determining means,
and control means for stopping the elevating drive means.

[0008]

[Operation] In the fall prevention device for the lifting pedestal constructed as described above, the lifting pedestal is raised and lowered by winding and unwinding the hanging member by the lifting driving means. When the elevating frame is raised and lowered, the tensile force acting on the hanging member is detected by the detection means, and the signal value from the detection means is input to the determination means. The signal value input to the determination means is compared with a preset reference value, so if the signal value is abnormal, it means that the tensile force acting on the hanging member exceeds the upper limit reference tensile force, or This means that the lower limit reference tensile force has not been reached, and the determining means can determine that the hanging member is in an abnormal state. When the determining means determines that the hanging member is in an abnormal state, the control means is activated based on a command signal from the determining means, and the lifting and lowering of the elevating frame is stopped. In this manner, since the presence or absence of an abnormality in the hanging member is determined by detecting the value of the tensile force acting on the hanging member, it is possible to prevent the hanging member from being cut.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the fall prevention device for a lift platform according to the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1 to 5 show a first embodiment of the present invention. In the figure, 31 indicates a gate-shaped guide rail extending in the vertical direction. The guide rail 31 consists of two vertical frames 3
2 and one horizontal frame 33. Horizontal frame 33 is located on top of vertical frame 32. Each vertical frame 32 is provided with fall prevention bars 34 as engagement means at predetermined intervals. The lower end of the guide rail 31 is fixed to the floor surface F.

[0011] Inside the guide rail 31, an elevating frame 4 is provided.
1 is arranged. The elevating frame 41 is composed of a box-shaped frame, and a metal material 40 to be melted is loaded thereon. A plurality of guide rollers 42 are provided on the sides of the elevating frame 41, and the guide rollers 42 can roll along the vertical frame 32 of the guide rail 31. The elevating frame 41 is movable in the vertical direction.

[0012] At the upper part of the guide rail 31, an elevating drive means 51 is provided. The lifting/lowering driving means 51 includes a motor 52 with a reducer, a frame 53, a drum 54, and a sprocket 5.
5, 56, roller chain 57, drive shaft 58, bearing 59
It consists of The pedestal 53 is fixed to the upper part of the vertical frame 32 of the guide rail 31, and the motor 52 with a reduction gear is attached to the pedestal 53. The drive shaft 58 is located above the horizontal frame 33 of the guide rail 31, and both ends are supported by bearings 59. A drum 54 is provided at the center of the drive shaft 58. A sprocket 55 is provided at the end of the drive shaft 58. The sprocket 55 is connected via a roller chain 57 to a sprocket 56 attached to the output shaft of the motor 52 with a reduction gear.

A wire rope 61 serving as a hanging member is wound around the drum 54 of the lifting drive means 51. One end of the wire rope 61 is connected to the upper part of the elevating frame 41, and the other end is connected to the balance weight 35. The drum 54 winds up and unwinds the wire rope 61 by rotating the drive shaft 58 in conjunction with the rotation of the motor 52 with a speed reducer. It is designed to go up and down.

A pair of load cells 62a and 62b are attached to the horizontal frame 33 of the guide rail 31 as detection means. Each load cell 62a, 62b receives a compressive load from a bearing 59 that rotatably supports a drive shaft 58 of the elevation drive means 51. That is, the tensile force acting on the wire rope 61 acts on each load cell 62a, 62b as a compressive load. The load cells 62a, 62b have a function of converting an external force acting on the load cells 62a, 62b into an electric signal proportional to the magnitude of the external force, and the signal values from the load cells 62a, 62b are transferred to the interface 65.
It is now entered into

A pair of fall prevention means 71 are provided above the elevating frame 41. The fall prevention means 71 is shown in FIG.
As shown in the figure, it is composed of a guide 72, a stopper pin 73, an air cylinder 74, a solenoid valve 75, air hoses 76, 77, and a hose reel 78. In the guide 72,
A stopper pin 73 is held so as to be freely removable. An air cylinder 74 is attached to one side of the guide 72, and a rod of the air cylinder 74 is connected to a stopper pin 73.

A hose reel 78 is provided on the drive shaft 58 of the elevating drive means 51. Two air hoses 76 and 77 are wound around the hose reel 78, and the lower end of one air hose 77 is branched into two and connected to one port of each air cylinder 74. The lower end of the other air hose 78 is branched into two and connected to the other port of each air cylinder 74. hose reel 7
The upper ends of the two air hoses 76 and 77 wound around the air hose 8 are connected to the solenoid valve 75. Compressed air is supplied to the electromagnetic valve 75 from a pressurized air source (not shown). The electromagnetic valve 75 performs a switching operation in response to a command signal from a control means 91, which will be described later.

As mentioned above, each load cell 62a, 6
The signal value from 2b is input to the interface 65. The interface 65 is a CPU as a determining means.
(central processing unit) 81. A reference value corresponding to the allowable tensile force acting on the wire rope 61 is input into the CPU 81 in advance. The CPU 81 uses preset reference values and signal values from each load cell 62a, 62b input via the interface 65 (in this embodiment, the load acting on one load cell 62a and the load acting on the other load cell 62b). Although the signal value corresponds to the sum of the load and the load, each signal value may be used.

A control means 91 is connected to the CPU 81 as a determination means. The control means 91 is the CPU 81
Based on the command signal from , the rotation of the motor 52 with a speed reducer of the elevating drive means 51 is stopped, and the stopper pin 73 of the fall prevention means 71 is engaged with the fall prevention bar 34 as an engagement means of the guide rail 31. Has a function. That is, when an abnormality occurs in the wire rope 61, a switching operation signal is output from the control means 91 to the solenoid valve 75, and compressed air is fed to the air cylinder 74 to cause the stopper pin 73 to protrude toward the guide rail 31 side, thereby causing the stopper pin 73 to protrude toward the guide rail 31 side. 7
3 and the fall prevention bar 34, the elevating frame 41 is held and stopped at that position. The control means 91, as shown in FIGS. 3 and 5,
2. Fall prevention pin protrusion command 93, motor stop command section 94
, an abnormality display output section 95, and a lowering command section 96.

A display means 98 is connected to the control means 91 . The display means 98 is composed of, for example, a CRT (cathode ray tube). The display means 98 is the control means 9
It has a function of displaying an abnormality of the wire rope 61 based on a signal from the abnormality display output section 95 of No. 1.

Next, the operation of the first embodiment will be explained with reference to the flowcharts of FIGS. 3 to 5. FIG. 3 shows a procedure for determining an abnormality in the wire rope 61 when the elevating frame 41 is raised. First, a process for determining whether or not there is an abnormality in the wire rope 61 is started in step 101 based on a lift command from the lift command section 92 of the control means 91 in FIG. Next, step 102
In order to detect the state of the wire rope 61 when the elevating frame 41 is actually elevated, a load cell 62a,
The start of measurement by 62b is slightly delayed. Step 10
3, the signal values from each load cell 62a, 62b are input to the determination means 81 via the interface 65. The signal value from each load cell 62a, 62b is determined by the determination means 8.
1, the process proceeds to step 104, where the sum of each signal value La, Lb of each load cell 62a, 62b is compared with a preset first reference value L1.

In step 104, as a result of comparing the sum of each signal value La, Lb with the first reference value L1, each signal value La
, Lb is smaller than the first reference value L1,
It is determined that the wire rope 61 has been cut, and the process proceeds to step 107.
, the fall prevention pin protrusion command section 93 of the control means 91
, outputs a signal to that effect to the motor stop command section 94 and the abnormality display output section 95. In step 104, as a result of comparing the sum of each signal value La and Lb with the first reference value L1,
When the sum of the signal values La and Lb is smaller than the first reference value L1, it is determined that the wire rope 61 is not in the cut state, and the process proceeds to step 105. In step 105,
When the sum of the signal values La and Lb is larger than the preset second reference value L2, a tensile force of a predetermined value or more is applied to the wire rope 61 and there is a risk of it breaking, that is, an overload state. It is determined that this is the case, and the process proceeds to step 108. In step 108, based on the determination result, the fall prevention pin command section 93 and the motor stop command section 94 of the control means 91
, outputs a signal to that effect to the abnormality display output section 95.

In this manner, when the determining means 81 determines that the wire rope 61 is completely cut or in a state where there is a risk of it being cut, the control means 91
A signal to that effect is output, and the hoisting of the wire rope 61 is stopped due to the stoppage of rotation of the motor 52 with a reduction gear, and the lifting of the lifting platform 41 is stopped. In addition, fall prevention means 7
By outputting a switching operation signal to the first electromagnetic valve 75, the stopper pin 73 is projected toward the vertical frame 32 of the guide rail 31 by the air cylinder 74. As a result, the stopper pin 73 is engaged with the fall prevention bar 34 provided on the vertical frame 32, and the lifting platform 4
1 is securely held in that position and stopped. In this embodiment, since it is usually possible to grasp the state in which the wire rope 61 is likely to break, the elevating load platform 40 is
This makes it possible to reliably stop the lift platform 41, eliminates the impact caused by the fall of the lift platform 41, and avoids adverse effects on the entire device as in the conventional case.

In step 105, each signal value La,
As a result of comparison with a second reference value L2 whose sum with Lb is set in advance, the sum of each signal value La and Lb becomes the second reference value L2.
When it is smaller than , it is determined that the wire rope 61 is in a normal state. Therefore, in this case, the elevating frame 4
1 continues to rise. In step 106, the elevating frame 41
If it is determined that the rise of has been completed, step 109
Then, the process of determining whether or not there is an abnormality in the wire rope 61 is completed. If it is determined in step 106 that the lifting of the elevating frame 41 is not completed, the process returns to step 103 and the above-described process is repeated.

[0024] When the lifting of the lifting frame 41 is completed, the metal material 40 loaded on the lifting frame 41 is put into a tower melter (not shown), and the metal material is melted.

FIG. 4 shows a modification of the flowchart shown in FIG. 3 with some changes. Here, step 105a is added between step 105 and step 106 in the flowchart of FIG. 3, and the load that adversely affects the wire rope 61 is counted to determine whether the wire rope 61 is good or bad. In other words, the sum of the signal values La and Lb of each load cell is compared with the third reference value L3, which is set slightly higher than the design load of the wire rope 61, although it does not result in an overload. The quality of the wire rope 61 is determined by determining how many times the sum of the values La and Lb exceeds the third reference value L3. This processing procedure will be explained below.

In step 105a, the sum of the signal values La and Lb from each load cell is compared with the third reference value L3, and the sum of the signal values La and Lb exceeds the third reference value L3. If so, proceed to step 105b;
The number of times the reference value L3 is exceeded is counted. This count is accumulated on each rise. Step 105
The cumulative count C at step b is compared with the reference number of times C0 at step 105c. Here, if the cumulative total C is the same as the reference number of times C0 or exceeds the reference number of times C0, it is estimated that the durability of the wire rope 61 has decreased due to a load that has an adverse effect on the wire rope 61, and the step Proceed to 105d. In step 105d, this is outputted to the abnormality display output section 95 of the control means 91, and based on the signal from the abnormality display output section 95, a message indicating that the wire rope 61 should be inspected is displayed on the display means 98 made of a cathode ray tube. Ru. Other configurations are similar to the configuration in FIG. 3.

FIG. 5 shows a procedure for determining an abnormality in the wire rope 61 when the elevating frame 41 is lowered. First, based on a descending command from the descending command section 96 of the control means 91 in FIG. 5, a process for determining whether or not there is an abnormality in the wire rope 61 is started in step 121. Next, the process proceeds to step 122, and in order to detect the state of the wire rope 61 when the elevating frame 41 is actually lowered, the start of measurement by the load cells 62a and 62b is slightly delayed. In step 123, the signal values from each load cell 62a, 62b are input to the determination means 81 via the interface 65. When the signal values from each load cell 62a, 62b are input to the determination means 81, the process proceeds to step 124, where the sum of each signal value La, Lb of each load cell 62a, 62b and a preset fourth reference value L4 are calculated. A comparison is made.

In step 124, as a result of comparing the sum of each signal value La, Lb with the fourth reference value L4, each signal value La
, Lb is smaller than the fourth reference value La, it is determined that the wire rope 61 has been cut, and the process proceeds to step 127, where the fall prevention pin protrusion command section 93 of the control means 91,
A signal to that effect is output to the motor stop command section 94 and the abnormality display output section 95. In step 124, each signal value L
As a result of comparing the sum of signal values La and Lb with the fourth reference value L4, if the sum of each signal value La and Lb is greater than or equal to the fourth reference value L4, it is determined that the wire rope 61 is not in the cut state. After making a determination, the process proceeds to step 125.

In step 125, each signal value La, Lb
The sum is compared with a preset fifth reference value L5. Here, the reference value L5 is a standard set in consideration of the fact that the apparent load on the elevating frame 41 becomes smaller when the frictional resistance between the guide roller 42 of the elevating frame 41 and the guide rail 31 increases. It is a value. The increase in frictional resistance between the guide rollers 42 and the guide rails 31 occurs due to poor rotation of the guide rollers 42 or because the clearance between the guide rollers 42 and the guide rails 31 is partially small, resulting in snagging. When the wire rope 61 comes off, an impactful tensile force acts on the wire rope 61, and repeating this causes the wire rope 61 to break. This shock value cannot be measured well because it occurs instantaneously when the hook is dislodged, and the hook is detected using the method described above. As a result of the comparison, if the sum of each signal value La, Lb is smaller than the fifth reference value L5, there is a risk that an impactful tensile force will be applied, and the tensile force that will have an adverse effect on the wire rope 61 when rising. It has been determined that there is a risk that the
Proceed to step 128.

In step 128, each signal value La, Lb
The number of times the sum of the values is determined to be smaller than the fifth reference value L5 is counted, and this number of times is accumulated. Step 12
The cumulative count C at step 8 is compared with the reference number C1 in step 129. Here, if the cumulative total C is the same as the reference number of times C1 or exceeds the reference number of times C1, it is assumed that the durability of the wire rope 61 has decreased due to an impactive tensile force that has a negative effect on the wire rope 61. Estimate and proceed to step 130. Step 130
Then, this is outputted to the abnormality display output section 95 of the control means 91, and a signal from the abnormality display output section 95 causes the display means 98 to display that an inspection of the wire rope 61 is instructed.

In step 125, each signal value La,
When the sum of Lb is greater than or equal to the fifth reference value L5, it is determined that the wire rope 61 is in a normal state, and the lowering of the elevating frame 41 is continued. If it is determined in step 126 that the lowering of the elevating frame 41 has been completed, step 1
31, the process for determining whether or not there is an abnormality in the wire rope 61 when the elevating frame 41 is lowered is completed. If it is determined in step 126 that the lowering of the elevating frame 41 is not completed, the process returns to step 123 and the above-described process is repeated. In this manner, in this embodiment, by counting the number of times that the wire rope and chain are subjected to an impactful tensile force, it is possible to clarify when to replace the wire rope and chain.

Second Embodiment FIGS. 6 and 7 show a second embodiment of the present invention. The second embodiment differs from the first embodiment only in the configuration of the guide rail and fall prevention means, and other parts are similar to the first embodiment, so similar parts are designated by the same reference numerals as in the first embodiment. By attaching it, the explanation of the corresponding part is omitted,
The different parts will be explained. The same applies to other embodiments to be described later.

In the first embodiment, the stopper pin 73 of the fall prevention means 71 was made to protrude toward the guide rail 31 when it was determined that there was an abnormality in the wire rope 61, but in this embodiment, the stopper pin 73 is made to protrude toward the guide rail 31 side at all times. It protrudes toward the guide rail side, and is configured to have a constant fall prevention function. In FIG. 6, a pair of fall prevention means 171 is provided above the elevating pedestal 41. The fall prevention means 171 is
It includes a guide 172, a stopper pin 173, a rod 174, a compression spring 175, an air cylinder 176, and the like. The guide 172 is fixed to the upper surface of the elevating frame 41. A stopper pin 173 is held in the guide 172 so as to be freely removable. The stopper pin 173 is connected to a rod 176a of an air cylinder 176 via a rod 174. The stopper pin 173 is movable in the in/out direction with respect to the rod 174. A compression spring 175 is disposed between the flange portion 174a of the rod 174 and the stopper pin 173 to bias the stopper pin 173 toward the guide rail 31 side. The stopper pin 173 is moved forward and backward relative to the guide rail 31 by an air cylinder 176.

In FIG. 6, a ratchet 134 is formed on the vertical frame 32 of the guide rail 31 as an engaging means. The ratchet 134 is a saw-shaped pawl, and a stopper pin 173 is inserted into the recess of the ratchet 134.
The tips of the two are fitted together. ratchet 13
4 and the stopper pin 173 are configured not to engage with each other in the upward direction of the elevating frame 41, but only in the downward direction of the elevating frame 41.

In the second embodiment configured as described above, when the elevating frame 41 is raised, the slope 134a of the ratchet 134 and the slope 173a of the stopper pin 173 come into contact with each other, and the slope 173a of the stopper pin 173 has a stopper A component force is generated that causes the pin 173 to retreat. This component force compresses the compression spring 175, and the engagement between the stopper pin 173 and the ratchet 134 is released. If it is determined that the wire rope 61 is abnormal during the ascent, the ascent of the elevating frame 41 is stopped and the stopper pin 173 is
By engaging with the ratchet 134, the elevating frame 41 is held and stopped at that position.

When the elevating frame 41 is lowered, the stopper pin 173 is moved to the guide 17 by the operation of the air cylinder 176.
2 side, the stopper pin 173 and ratchet 13
4 is released. As a result, the elevating frame 41
becomes possible to descend. If it is determined that the wire rope 61 is abnormal during descent, the descent of the elevating platform 41 is stopped, and the stopper pin 173 is moved to the air cylinder 17.
6 protrudes, and the stopper pin 173 and ratchet 1
34, the elevating pedestal 41 is held and stopped at that position.

Third Embodiment FIG. 8 shows a third embodiment of the present invention. In each of the embodiments described above, the load acting on the drive shaft of the lifting drive means is detected by a load cell, but in this embodiment, it is possible to directly detect the load acting on the wire rope. As shown in FIG. 8, the lower end of the wire rope 61 is connected to the upper surface of the elevating frame 41 via a load cell 162 as a detection means. In this embodiment, the signal cable 1 leads the output signal of the load cell 162 to the determination means.
63, but as mentioned above, it is possible to directly detect the tensile force acting on hanging members such as wire ropes, and the hoist wire rope or chain block chain can be used to directly raise and lower the lifting platform. advantageous in some cases.

In each of the above embodiments, a wire rope is used as the hanging member, but the hanging member may also be a chain or a string-like member woven from a fibrous material with high tensile strength. It's okay.

[0039]

Effects of the Invention As explained above, the following effects can be obtained by using the fall prevention device for an elevating frame according to the present invention. (b) Compare the signal value from the detection means for detecting the tensile force acting on the hanging member with a preset reference value,
Since the determining means determines whether or not there is an abnormality in the hanging member when the elevating frame is raised or lowered, it is possible to prevent the hanging member from being cut. Therefore, the elevating pedestal is prevented from flying out due to the elevating pedestal falling, and damage to the device due to impact is prevented, and repair costs such as repair work are also eliminated. (b) By applying the present invention to a lifting device using a commercially available hoist or chain block, the safety of the inexpensive and simple lifting device can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a fall prevention device for an elevating pedestal according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG. 1;

FIG. 3 is a flowchart showing a procedure for determining a wire rope abnormality when the elevating frame is raised in the apparatus shown in FIG. 1;

FIG. 4 is a flowchart showing a modification of FIG. 3;

FIG. 5 is a flowchart showing a procedure for determining a wire rope abnormality when the elevating gantry is lowered in the apparatus shown in FIG. 1;

FIG. 6 is a schematic configuration diagram of a fall prevention device for an elevating pedestal according to a second embodiment of the present invention.

FIG. 7 is a partially enlarged sectional view of FIG. 6;

FIG. 8 is a schematic configuration diagram of a fall prevention device for an elevating pedestal according to a third embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing an example of a conventional fall prevention device for an elevating frame.

FIG. 10 is a schematic configuration diagram of a fall prevention device described in Japanese Utility Model Application Publication No. 56-151265.

FIG. 11 is a schematic configuration diagram of a safety device described in Japanese Utility Model Application Publication No. 56-148079.

FIG. 12 is a schematic configuration diagram of a wire rope breakage detection device described in Japanese Utility Model Application Publication No. 55-32381.

[Explanation of symbols]

31 Guide rail 34 Engagement means 41 Lifting frame 51 Lifting drive means 61 Hanging member (wire rope) 62a, 62b Detection means (load cell) 71 Fall prevention means 73 Stopper pin 81 Judgment means (CPU) 91 Control means 134 Engagement means 162 Detection means (load cell) 171 Fall prevention means 173 Stopper pin

Claims (1)

[Claims] 1. A guide rail extending in the vertical direction, an elevating pedestal movable in the vertical direction along the guide rail, a chain-shaped or rope-shaped hanging member for suspending the elevating pedestal, and the hanging member. an elevating drive means for elevating and lowering the elevating frame by winding and unwinding the elevating frame; and a detecting means for detecting a tensile force acting on the hanging member;
determining means for comparing the signal value from the detecting means and a preset reference value to determine whether an abnormality has occurred in the hanging member;
A fall prevention device for an elevating cargo platform, comprising: control means for stopping the elevating drive means based on a command signal from the determining means.