JP7612954B2 - Method for winding cable around a cable reel for power supply to a crane lifting device - Google Patents

Description

The present invention relates to a method for winding a cable on a vertical winding cable reel to supply power to a hoisting device suspended by a hoisting device installed on a club trolley of a crane.

In a vertical winding cable reel for supplying power to a hoisting device suspended from a crane, the cable being wound onto the cable reel is subjected to tension due to the cable's own weight, and the cable reel rotates the cable drum of the cable reel with a torque strong enough to overcome this tension and wind up the cable, winding the cable. In the process, the cable is subjected to large pulling forces, bending forces, and twisting forces, and as the cable is used in a harsh manner, it is subject to severe damage, and technology to alleviate this damage is required. For example, the methods described in Patent Documents 1 to 3 have been proposed.

JP 2010-260684 A JP 2018-162147 A JP 2021-66553 A

Due to space limitations, vertical winding cable reels installed on the club trolley of a crane use either a multi-row, multi-layer winding drum or a multi-row, single-layer winding drum.
In this type of drum, the cable is wound in a spiral shape around the cable drum, but the section of cable being wound is pulled straight down vertically, so that it always rides on top of the adjacent cable that is already wound.
At this time, the rubber coating (sheath material) on the surface of the cable being wound grips the rubber coating (sheath material) on the surface of the adjacent cable that has already been wound, and the cable being wound is twisted as it is wound.
The twisting that occurred at this time caused damage to the cable.

Incidentally, Patent Document 3 describes a method for calculating the radius from the center of the cable drum of each layer of cable wound on a cable reel, and calculating the cable sagging length and the corresponding cable sagging weight from the amount of cable pulled out from that position, and also describes a method for calculating the torque that the sagging cable applies to the cable drum by multiplying the radius and weight.
However, the radius when the cable is wound is not the radius at the point where the cable has finished being wound, but the point where the cable rides over the adjacent cable when being wound. Therefore, the radius when the cable is wound is larger than the radius described in Patent Document 3. If the cable winding torque is calculated based on the calculation in Patent Document 3, the winding torque will be smaller than the required torque, resulting in a disordered winding of the cable due to insufficient winding torque.

In consideration of this problem, the present invention aims to provide a vertical winding cable reel for supplying power to a hoisting device suspended from a crane, which reduces the risk of cable breaks and short circuits caused by bending of the wires inside the cable, and of the cable becoming irregularly wound.

In order to solve the above problems, the cable winding method of the present invention for a cable reel for powering a crane hoisting tool is a vertical winding type cable reel for powering a hoisting tool suspended from a crane, and is characterized in that the drum type for winding the cable around the cable drum of the cable reel is a multi-row winding (multi-row multi-layer winding or multi-row single-layer winding) drum type, and by applying a lubricant to the surface of the cable to be wound around the cable reel, the cable hanging down vertically is wound on top of the cable that has already been wound in a spiral shape, so that the cable to be wound on top of the already wound cable once rides up and is prevented from being twisted when being wound.

In this case, mineral oils can be used as the lubricant.

In addition, when a cable hanging down vertically is wound on top of a cable that is already wound in a spiral shape around a cable drum, the cable to be wound on top of the already wound cable first climbs up, and then the torque to wind the cable is calculated. The load torque acting on the cable drum due to the weight of the hanging cable is calculated as the fulcrum radius, which is the distance from the center of the cable drum to the center position of the already wound cable of the layer of cable to be wound, plus the climbing distance of the cable to be wound on the already wound cable, and this can be reflected in the value of the winding torque.

In addition, the frictional resistance between the cables that occurs when winding the cable onto the cable drum, the transmission loss that occurs between the reel drive motor and the cable drum, and the acceleration torque that accelerates the inertial force of the rotating part of the cable drum and the moving body of the cable can be calculated and reflected in the winding torque value.

The cable winding method for a cable reel for power supply to a crane hoisting device of the present invention eliminates cable twisting that occurs when winding a vertically wound cable, preventing damage to the cable and preventing irregular winding due to insufficient cable winding torque. This makes it possible to take measures against cable damage caused by irregular winding and the cable climbing over the flange of the cable drum and falling off, thereby improving the reliability of the cable reel.

1 is a schematic explanatory diagram of a crane for implementing a cable winding method for a cable reel for power supply to a crane hoisting tool according to the present invention; FIG. 2 is an explanatory diagram of the structure of an electric cable reel. FIG. 2 is an explanatory diagram of a type of drum of a cable reel. 1A to 1C are explanatory diagrams of the movement of a cable when it is wound onto a cable reel. FIG. 13 is an explanatory diagram of the dimension of a hanging cable climbing over an adjacent cable. FIG. 4 is an explanatory diagram of a winding state of the cable. FIG. 13 is an explanatory diagram of what happens when a cable is twisted. FIG. 1 is an explanatory diagram of a cable defect example.

Below, an embodiment of the cable winding method for a cable reel for power supply to a crane hoisting device of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a crane for carrying out the method of winding a cable around a cable reel for power supply to a crane hoisting gear of the present invention.
A hoisting device GB, which is completely supported by a wire rope WR, is suspended from a wire drum WD on a club trolley TR of a crane CR, and the hoisting device GB is raised and lowered solely by the rotational force of the wire drum WD.
A cable CA hangs down under constant tension from a cable reel RE arranged next to the wire drum WD, is fixed with a fixing bracket FS, and is supplied with power to a hoisting device GB.
The cable reel RE always generates a winding torque in the winding direction, keeping the cable CA under tension. When the sling GB is wound down, the cable CA wound around the cable reel RE is pulled out while maintaining a tension due to the winding torque of the cable reel RE, and when the sling GB is wound up, the cable CA is wound around the cable reel RE while maintaining a tension due to the winding torque of the cable reel RE.
At this time, the winding torque of the cable reel RE is set to a weak torque that only supports the cable CA and the fixing bracket FS, does not support the load of the hoisting device, and is set to a weak torque that only follows the up and down movement of the hoisting device GB.

FIG. 2 shows an example of the structure of an electric cable reel.
The cable CA wound around the cable drum CD is connected to a slip ring SR through a hollow shaft SH from the cable drum, and is electrically connected to the rotating cable CA through a fixed wiring. A reel drive motor DM connected to the hollow shaft SH generates a predetermined rotational torque controlled by the detection of a rotational position detector PG, and transmits it to the cable drum CD via the hollow shaft SH to generate a torque for winding up the cable CA.

FIG. 3 illustrates the types of cable drum CD.
Figure 3 (1) shows a single-row, multi-layer winding drum. Due to its narrow cable drum width and large outer diameter, it is widely used for power supply while traveling on gantry cranes.
FIG. 3(2) shows a multi-row, multi-layer winding drum, and FIG. 3(3) shows a multi-row, single-layer winding drum.
The cable winding method for a cable reel for power supply to a crane hoisting equipment of the present invention is intended for the multi-row, multi-layer winding drum of Figure 3 (2) and the multi-row, single-layer winding drum of Figure 3 (3), which are shaped so that they can be placed even in a narrow space above the club trolley TR.

FIG. 4 illustrates how to wind a cable around a multi-row winding drum.
The cable CA pulled out from the cable drum CD at the cable pull-out position CO is wound in a spiral shape with one turn of the cable CA shifting sideways by one turn at 360°.
On the other hand, the hanging cable CA to be wound is pulled vertically, so that it starts from the drum apex A and moves straight up onto the adjacent cable CA that is already spirally wound, toward the drum horizontal point B, which becomes the drum hanging point CAL, and the overlap with the adjacent cable CA at this point is 0.5r/90°, whereas the cable is wound with a 2r offset over 360°. Here, r is the radius of the cable.
The cable ride-over dimension X at this time is as shown in FIG. 5, and is calculated as 1.32r from formula (1).
X ² = (2r) ² - (1.5r) ² ... Formula (1)
X=1.32r

At this time, the weight hanging down from the cable sagging point CAL is calculated by multiplying the weight per unit length of the cable by the sagging length L plus the weight of the fixing bracket, and the torque applied to the cable drum from the cable side is calculated by multiplying this total weight by the winding radius R. However, this winding radius R is not the first layer radius R1 described in Patent Document 3, but is the first layer radius R1 plus the climb-up dimension X. Therefore, a torque greater than the torque described in Patent Document 3 is applied from the cable side during winding. Therefore, if the winding torque is set using the calculation method described in Patent Document 3, a torque shortage will occur, and in reality, only the climb-up dimension X must be added to the support radius of each layer.
In addition, since the spiral of the cable wound around the drum is not a perfect spiral but meanders slightly, it is safe to set the cable riding dimension X to one cable's length (2r) more than 1.32r.

At the drum horizontal point B, the cable hanging point CAL is located at the riding position, and when the cable drum winding RU is performed, the riding cable CA gets stuck in the cable drum CD while a twist RO occurs in the cable CA as it moves from the drum horizontal point B to the drum apex A.
Then, when the first layer is finished and the second layer begins in the cable winding sequence CT, the spiral direction of the cable CA reverses, and the direction of the twist RO also reverses, adding a twist as the cable is wound in a spiral shape.
Figure 6 (1) shows the state in which cable CA moves from the drum horizontal point B toward the top of the drum. After riding up onto the adjacent cable CA at the cable hanging point CAL, the rubber coating on the surface of the cable that is being wound from the cable hanging point CAL grips the circumference of the rubber coating (sheath material) on the surface of the cable CA, which has already been wound in a spiral shape, and the cable is wound onto the cable drum CD while generating a twist RO.

At this time, the core wires of the cable are twisted in a certain direction, as shown in Fig. 7. When a twist is applied in the same direction as the twisting direction TW of this core wire, the core wire is pulled and tightened, and a strong resistance is exerted, but when a twist RO is applied in the opposite direction to the twisting direction TW of the core wire as shown in Fig. 7, the core wire is untwisted, and a core wire bending BD occurs as shown in Fig. 8, causing the strands to break and break the insulation, resulting in a short circuit with the adjacent core wire, or the core wire breaking.
Whether the twist direction TW of the core wires is the same or opposite depends on the position of the cable pull-out position CO and the winding direction, but in the case of a multi-row, multi-layer type, the first and second layers are twisted in opposite directions, so cable defects due to twist RO will occur in either the first layer (odd layer) or the second layer (even layer).

In the multi-row single-layer cable drum shown in Fig. 3 (3), twist RO continues to be applied in the same direction while the multiple rows are being wound, and the accumulation of twist RO becomes enormous in the portion where the cable CA is fully wound. Even if the twist direction TW of the core wire and the twist RO direction are the same in the portion wound around the cable drum CD and the direction of the core wire is the same and the core wire is tightened, a twist opposite to the amount of twist that was applied while being wound around the cable drum CD occurs in the hanging portion, in which case the core wire untwists in the hanging portion near the fixing metal, causing a core wire bend BD as shown in Fig. 8.
In this way, even if the winding direction of a multi-row, single-layer cable drum is devised, problems will occur either in the hanging portion or in the wound portion. If a twist RO occurs in the cable CA, the core wire bending BD shown in Figure 8 is unavoidable.

The mechanism of irregular winding that occurs when the winding torque is set smaller than the required torque while a twist RO occurs during winding of the cable CA will be described with reference to Figures 6 (1) and (2).
When the cable approaches the end of the layer with twisted cable RO, the amount of twisted cable RO accumulates. If the winding torque is insufficient at this time, the force that tries to pull the cable toward the cable drum CD and wind it will be greater than the force that tries to lift the cable onto the adjacent cable CA to return the twisted cable RO due to the repulsive force of the accumulated twisted cable RO, and the cable will completely ride up onto the adjacent cable CA, resulting in a disorderly winding state.
Once this occurs, it becomes impossible to wind the cable in an orderly manner, and the cable ends up climbing up onto the cable CA. In the worst case scenario, the cable may climb over the drum flange DT and fall off DP, making it impossible to continue operating the crane.
This phenomenon occurs in both multi-row, multi-layer winding and multi-row, single-layer winding.
Even if this irregular winding phenomenon does not result in a falling-off DP, it will disrupt the twisting of the core wires CC, causing short circuits between the core wires in the cable CA or wire breakage.

The torque required to prevent undulation during winding is not calculated in a static state as described in Patent Document 3, but is calculated by adding the riding dimension X, which is the dynamic state of the cable when it is wound, to the static cable position of each layer, and multiplying this riding dimension X by the load applied to the hanging portion of cable CA to calculate the load torque.
Furthermore, if necessary, the frictional resistance between the cables when pulling the riding-up cable CA in the direction of the cable drum CD, the transmission loss occurring between the reel drive motor DM and the cable drum CD, and the acceleration torque for accelerating the inertial force of the rotating parts such as the cable drum CD and the moving bodies such as the cable CA can be calculated and reflected in the value of the winding torque.
By generating the required torque as described above, the random winding phenomenon can be prevented.

Furthermore, in the cable winding method for a cable reel for power supply to a crane hoisting gear of the present invention, in order to eliminate twisting RO, which is a cause of cable malfunction, a lubricant GR is applied generously to the surface of the cable CA.
Here, "applying generously" means applying a generous amount by hand to fill in the gaps in the cable CA when setting up the crane CR, which allows the applied condition to be maintained for several years to around 10 years.
When the lubricant GR is generously applied to the surface of the cable CA, as shown in Figure 6 (3), the cable CA to be wound rides up on the adjacent cable CA that is already spirally wound, and then slides down onto the cable drum CD without the surface of the adjacent cable CA and the surface of the cable to be wound gripping each other, and without the occurrence of twisting RO.

When considering only the relationship between the lubricant GR and the chloroprene rubber that is the rubber coating (sheath material) on the surface of the cable CA, it is desirable to use a silicone oil, which has long-term stability. However, silicone oil dries out in a short period of time, which has the disadvantage of requiring more frequent maintenance.
For this reason, in this embodiment, a mineral oil-based grease that can ensure lubrication for a long period of time is used. Although mineral oil-based grease deteriorates chloroprene rubber over the long term, the extension of the life of the cable CA by preventing mechanical damage to the cable CA due to twisting RO is more important than the chemical deterioration.

The effect of applying lubricant GR to cable CA is that it not only prevents core wire bending BD inside the cable by eliminating twisting RO, but also eliminates twisting of cable CA caused by twisting RO in the hanging portion of cable CA, eliminating the constraint of hanging cable CA due to twisting and allowing the hanging cable CA to move flexibly. In addition, it also reduces the risk of uncoiled winding by eliminating the rise of adjacent cables due to twisting RO.

The cable winding method for a cable reel for power supply to a crane hoisting device of the present invention has been described above based on an embodiment thereof, but the present invention is not limited to the configuration described in the above embodiment, and the configuration can be changed as appropriate within the scope of the spirit of the present invention.

The cable winding method for a cable reel for power supply to a crane hoisting device of the present invention can eliminate the twisting of the cable that occurs when winding the cable on a multi-row multi-layer drum or multi-row single-layer drum cable reel, and can eliminate the associated cable problems. In addition, by clarifying the fulcrum radius at which the load of the hanging part of the cable acts on the cable drum when winding the cable, it is possible to calculate the accurate load torque, which can be effectively used industrially when operating cable reels.

CR Crane TR Club trolley WD Wire drum WR Wire rope GB Lifting device RE Cable reel CA Cable FS Fixing bracket L Drooping length CD Cable drum SH Hollow shaft DM Reel drive motor PG Rotational position detector BR Brake BB Bearing TB Terminal block SR Slip ring CB Carbon brush CT Cable winding order CAL Cable drooping point R1 1st layer radius R2 2nd layer radius R3 3rd layer radius R Winding radius CO Cable pull-out position A Drum top B Drum horizontal point C Drum bottom RU Winding RO Twist r Cable radius X Riding dimension GR Lubricant DT Drum flange DP Dropout CC Core wire TW Core wire twist direction BD Wire bending

Claims (3)

A method for winding a cable on a vertical winding type cable reel for supplying power to a hoisting device suspended from a crane, comprising the steps of:
The cable reel is configured such that a method of winding the cable around a cable drum is a multi-row winding method in which the cable is wound around the cable drum in a spiral shape ,
A lubricant is applied to the surface of the cable wound around the cable drum ,
This method of winding a cable onto a cable reel for power supply to a crane hoisting gear is characterized in that when a vertically hanging cable rides up onto a cable that has already been wound in a spiral shape and is then wound, the rubber coatings on the surfaces of the cables do not grip each other, thereby preventing the cable from being twisted. The cable winding method for a cable reel for power supply to a crane hoisting device according to claim 1, characterized in that the lubricant is made of mineral oil. 3. The method for winding a cable onto a cable reel for power supply to a crane hoisting tool according to claim 1, wherein the support radius used in calculating the load torque of the cable reel is calculated by adding the distance from the center position of the cable drum to the center position of the cable already wound thereon and the distance that the cable climbs up onto the already wound cable and then is wound.

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