Parent Hook Miswinding Prevention Device

Abstract

To provide a parent hook accidental winding prevention device that even if a crane operator winds up a main winding rope by incorrect operation when a parent hook is suspended below the crane and fixed, can stop this winding in a mechanically safe manner.SOLUTION: In this device A, a wire rope between arms of a pair of arms is disposed between a boom 1 and a main winding rope 11 and adjacent to the main winding rope 11, and when winding of the main winding rope 11 occurs, drawing of the main winding rope 11 to the boom 1 side is received by the wire rope, a limit switch senses pulling force from this wire rope and transmits a control signal to a controller, and the controller stops the winding of the main winding rope 11 by a main winding winch.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present invention relates to a parent hook anti-overwinding device that is used for various types of cranes such as crane trucks and enables safe lifting operations by the crane.

Background Art

[0002] A general crane used in construction and civil engineering work is disclosed in Patent Document 1 and the like, and an example thereof is shown in FIG. 17.

[0003] The crane C in FIG. 17 is one of mobile cranes and is mounted on a slewing platform rotatably installed on the upper part of a crawler-type vehicle, and is configured as a so-called crane truck. In this crane C, the boom 1 is supported on the slewing platform on the vehicle so as to be able to rise and fall via a boom support bracket, and is driven by a boom hoist winch, a boom hoist rope, and a guide cable installed on the slewing platform. Further, in this crane C, the boom 1 includes a main boom M1 and an upper boom S1 extending from the tip of the main boom M1, and boom point sheaves 101 and 102 are provided at the tip of the main boom M1 and the tip of the upper boom S1, respectively. Each winch for main winding and auxiliary winding is also installed on the slewing platform, and the main winding rope 11 and the auxiliary winding rope 12 are respectively fed out from each winch for main winding and auxiliary winding, and are wound around the boom point sheaves 101 and 102 at the tip of the main boom M1 and the tip of the upper boom S1. Then, the main winding rope 11 is looped between the boom point sheave 101 and the hook sheave provided on the parent hook 13, and the tip is coupled to an end pin provided inside the tip of the main boom M1. By this main winding rope 11, the parent hook 13 is suspended from the tip of the main boom M1, and the child hook 14 is connected to the tip of the auxiliary winding rope 12 and is suspended from the tip of the upper boom S1. Note that the upper boom (S1) shown in FIG. 17 is also referred to as an auxiliary boom and is called an auxiliary sheave among those skilled in the art (the same applies to the upper boom (S1) shown in FIG. 18).

[0004] In this way, by separately paying out and winding in the main winding rope 11 and the auxiliary winding rope 12 from each winch for the main winding and the auxiliary winding, the parent hook 13 and the child hook 14 are raised and lowered.

[0005] This crane C has such a configuration. In various construction and civil engineering works, the parent hook 13 is mainly used for low-speed hoisting operations with large loads, and the child hook 14 is mainly used for high-speed hoisting operations with small (light) loads.

[0006] Also, for this type of crane C, in order to prevent wire cutting accidents due to overwinding of the main winding rope for raising and lowering the parent hook and the auxiliary winding rope for raising and lowering the child hook, and tipping accidents of the boom to the rear side, overwinding prevention devices for the main winding rope and the auxiliary winding rope are provided. This type of overwinding prevention device is disclosed in Patent Document 2 and the like.

[0007] The overwinding prevention devices for the main winding rope and the auxiliary winding rope are each composed of a limit switch attached to the boom, a wire rope suspended from the switch arm of the limit switch, and a weight. In this case, the weight has a through hole, and the main winding rope and the auxiliary winding rope penetrate through this through hole, so that the weight can move up and down along the main winding rope and the auxiliary winding rope. The switch arm of the limit switch is pulled down by the weight and is in the off state. When the main winding rope and the auxiliary winding rope are wound in from this state and just before the overwinding state, the upper ends of the parent hook and the child hook push up the weight, the wire rope loosens, the switch arm of the limit switch moves up and turns on, and it is detected that it is just before the overwinding of the rope. Then, a detection signal is sent from the limit switch to the control unit of the winch, and the winding in of the main winding rope and the auxiliary winding rope by the winch is stopped. Thus, overwinding of the main winding rope and the auxiliary winding rope is prevented.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

[0009] By the way, in the lifting work using a crane in construction civil engineering work, while one of the main hook or the sub-hook is being used, the other is not used and is in a suspended state. For example, as shown in FIG. 17, in the case of an operation of suspending a pile with the sub-hook 14 and inserting it into a hole excavated in the ground, the unused main hook 13 is wound up on the upper side of the crane C main body and is in a suspended state. Then, when the pile is moved up and down by the vertical movement of the sub-hook 14 during the work, a large load is applied to the crane due to frictional resistance or the like, the main body and the boom shake, and the unused main hook 13 that is used to amplify it swings back and forth and collides with the boom 1, and the boom frame and the lattice may be damaged. When the boom 1 is damaged and deformed in this way, it is necessary to replace the damaged part of the boom 1 with a sound one and conduct an administrative (Labor Standards Inspection Office) inspection. In this case, the construction will stop for at least three days, and the construction will be delayed accordingly.

[0010] Therefore, as the construction side of the work, in order to avoid such a delay in the work and prevent the front and back swings of the unused main hook 13, as shown in FIG. 18, the main hook 13 is lowered to below the crane C, a wire W is attached to the crane C, this wire W is hung on the main hook 13, and it is appropriately tightened to fix the main hook 13 as a countermeasure.

[0011] However, even in this case, if the operator of the crane C accidentally operates the main hoist winch and winds up the main hoist rope 11, the aforementioned overwind prevention device installed on the crane C will not work and mechanical detection is not possible. Therefore, unless the winding of the main hoist rope 11 by the main hoist winch is stopped, the winding up of the main hoist rope 11 will continue. As a result, naturally, due to excessive winding at the lower part of the main hoist rope 11, the wire W will break. When the wire W breaks, the parent hook 13 will be in a pendulum state and swing back and forth, and there is a risk of colliding with and damaging objects close to the crane C. In this case, the lower the boom 1's elevation angle, the greater the range and force of the swing of the parent hook 13. Since the weight of the parent hook 13 mainly ranges from 500 kg to 1,000 kg, it is not difficult to imagine that the impact force and destructive force will be quite large.

[0012] In addition, in order to avoid such wire cutting, measures such as using two wires to reinforce the wire or moderately tensioning one of the two wires and making the other wire about several tens of centimeters longer and in a slack state so that the parent hook can be held by the other wire even if one wire breaks can be considered. However, even in this case, when the first wire breaks due to the winding up of the main hoist rope, if the operator does not immediately stop the winding of the main hoist rope, the second wire will also break, and the result will be the same.

[0013] The present invention solves such conventional problems. In lifting operations using this type of crane, in order to prevent the front and back swing of the unused parent hook, when the parent hook is lowered and fixed to below the crane, even if the operator of the crane accidentally operates the main hoist winch and winds up the main hoist rope, the winding of the main hoist rope can be mechanically and reliably and safely stopped. The object is to provide an excellent anti-miswinding device for the parent hook.

Means for Solving the Problems

[0014] To achieve the above object, the present invention It has at least a boom point sheave for main winding and a boom point sheave for supplementary winding at the tip side, and a boom that is supported so as to be able to undulate on the base and is driven by a driving device installed on the base, and is fed out from one of a main winding winch or a supplementary winding winch installed on the base, and is wound around the main winding boom point sheave on the tip side of the boom. A main winding rope, a supplementary winding rope that is fed out from the other and wound around the supplementary winding boom point sheave, and the main winding rope is connected to the tip of the boom and is suspended on the tip side of the boom, and the parent hook and is connected to the tip of the supplementary winding rope and is suspended on the tip side of the boom the child It is equipped with a hook and a controller that controls the operations of the driving device, the main winding winch, and the supplementary winding winch. By paying out and winding up the main winding rope by one of the main winding winch or the supplementary winding winch, and paying out and winding up the supplementary winding rope by the other, it is equipped with a crane that raises and lowers the main hook and the sub-hook, and is a main hook miswinding prevention device that prevents the main hook from being miswound, A pair of arms that are arranged in parallel in the width direction and project forward facing the main winding rope on the lower side of the boom is a cord-like stretched between the pair of arms, and is provided on one of the pair of arms, is connected to one end of the cord-like, and the A tension spring for pulling in a cord shape, and provided on the other is connected to the other end of the cord-like and is operatively connected to is electrically connected to the controller via a signal line, the A tension detector that senses the cord-like pulling force and transmits a control signal to the controller to stop the winding of the main winding rope by the main winding winch or the supplementary winding winch 、 is is provided, During the suspension work by the supplementary winding rope and the sub-hook, each arm arranges the cord between the arms so that it is between the boom and the main winding rope in a state where the boom and the main winding rope are lowered and the main hook is lowered to the lower side of the crane and fixed. When the main hoist rope is wound up by the main hoist winch or the auxiliary hoist winch during the hanging operation, the pulling of the main hoist rope toward the boom side is elastically received and pressed in a cord-like manner, and the pulling force from the cord-like member pulled by the pulling of the main hoist rope toward the boom side is sensed by the tension detector and transmitted. Based on the control signal, the controller stops the winding of the main hoist rope by the main hoist winch or the auxiliary hoist winch. This is the gist.

[0015] Also, it is preferable that each part of this parent hook anti-overwinding device has the following configuration. (1) Each of the pair of arms is attached to the front of the boom via a mounting bracket so as to be able to project forward from the front of the boom and foldable along the front. (2) The tension detector consists of a limit switch. (3) The tension spring consists of a tension coil spring. (4) The cord-like member consists of a wire rope. (5) The crane is provided with an anti-overwinding device for the main hoist rope and the auxiliary hoist rope. Each of the anti-overwinding devices is electrically connected to the controller via a signal line. The tension detector is connected to the controller by connecting the signal line of the tension detector to the signal line between each anti-overwinding device and the controller via a branched wiring connector.

Effect of the Invention

[0016] According to the parent hook anti-overwinding device of the present invention, with the above configuration, in the hanging operation using the crane as described above, in order to prevent the swing of the unused parent hook back and forth, when the parent hook is lowered to the lower part of the crane and fixed, even if the crane operator accidentally operates the main hoist winch or the auxiliary hoist winch and winds up the main hoist rope, the winding of the main hoist rope can be mechanically and surely stopped safely, and the present invention has a unique and remarkable effect.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Embodiments for Carrying Out the Invention

[0018] Next, embodiments for carrying out this invention will be described with reference to the drawings. Fig. 1 schematically shows a main hook overwinding prevention device installed on a crane. Figs. 2 to 13 show the overall configuration of the main hook overwinding prevention device, and Figs. 14 and 15 show the configuration of the main part of the main hook overwinding prevention device.

[0019] As shown in Fig. 1, the crane C has at least a boom point sheave 101 for main winding and a boom point sheave 102 for auxiliary winding on the tip side, is supported on the base 10 so as to be able to rise and fall, and is driven by a driving device (not shown) installed on the base 10. A boom 1, a main winding rope 11 fed out from one of a main winding winch (not shown) or an auxiliary winding winch (not shown) installed on the base 10 and wound around the boom point sheave 101 for main winding on the tip side of the boom 1, an auxiliary winding rope 12 fed out from the other and wound around the boom point sheave 102 for auxiliary winding, a main hook 13 and a sub-hook 14 connected to the tips of the main winding rope 11 and the auxiliary winding rope 12 and suspended on the tip side of the boom 1, and a controller (not shown) for controlling the operations of the driving device, the main winding winch, and the auxiliary winding winch. By feeding out and winding up the main winding rope 11 by one of the main winding winch or the auxiliary winding winch and feeding out and winding up the auxiliary winding rope 12 by the other, the main hook 13 and the sub-hook 14 are raised and lowered. In this case, the main hook 13 is raised and lowered by paying out and winding in the main winding rope 11 by the winch for the main winding, and the sub-hook 14 is raised and lowered by paying out and winding in the auxiliary winding rope 12 by the winch for the auxiliary winding. Also, in this case, the boom 1 is composed of a main boom M1 and an upper boom S1 extending from the tip of the main boom M1. The tip side of the boom 1 refers to the tip of the main boom M1 and the tip of the upper boom S1. Boom point sheaves 101 and 102 are rotatably disposed at the tip of the main boom 2 and the tip of the upper boom 3, respectively. Here, the upper boom (S1) is also referred to as an auxiliary boom as described above and is called an auxiliary sheave among those skilled in the art. The main winding rope 11 is looped between the boom point sheave 101 and a hook sheave (not shown) provided on the main hook 13, and the tip is coupled to an end pin (not shown) provided inside the tip of the main boom M1. The main hook 13 is connected to the tip of the main winding rope 11 and is suspended from the tip of the main boom M1. The sub-hook 14 is connected to the tip of the auxiliary winding rope 12 and is suspended from the tip of the upper boom S1. Furthermore, in this case, the crane C is configured as a so-called crane vehicle, with the base 10 mounted on a slewing platform rotatably installed on the upper part of a crawler vehicle.

[0020] Also, in this crane C, similar to the prior art, in order to prevent wire cutting accidents due to overwinding of the main winding rope 11 for raising and lowering the main hook 13 and the auxiliary winding rope 12 for raising and lowering the sub-hook 14, and to prevent the boom 1 from tipping backward, overwind prevention devices for the main winding rope and the auxiliary winding rope are provided. Since the overwind prevention devices for the main winding rope and the auxiliary winding rope basically have a common configuration, here, only the overwind prevention device B for the main winding rope is shown in FIG. 14 and described, and the illustration and description of the overwind prevention device for the auxiliary winding rope are omitted.

[0021] As shown in Fig. 14, the overwind prevention device B is of a standard specification, that is, a general one, and is composed of an overwind detector 21, a weight suspension rope 22, and a weight 23. The overwind detector 21 is composed of a known limit switch (hereinafter referred to as the limit switch 21), and is configured to transmit a control signal by the operation of an operating pin that senses the tension from the weight suspension rope 22. In this case, the operating pin is arranged in the main body case of the limit switch 21 via a coil spring, and is normally biased upward by the biasing force of the coil spring to be in an on state. The operating pin is pulled downward by the weight of the weight 23 connected via the weight suspension rope 22 to be in an off state. The weight suspension rope 22 is composed of a wire rope (hereinafter referred to as the wire rope 22), and is connected to the lower end of the operating pin of the limit switch 21 and hangs downward below the operating pin. The weight 23 has a through hole (not shown) for passing the main hoist rope 11 through the central portion, and is connected to the lower end of the wire rope 22. Note that the position of this weight 23, in other words, the length of the wire rope 22, is set such that the weight 23 can be pushed up by the parent hook 13 when the parent hook 13 is moved upward to a position just before it becomes difficult to ensure a predetermined safety distance (a distance at which the parent hook 13 does not contact the tip side of the boom 1) from below the tip side of the boom 1.

[0022] The overwind prevention device B is configured as described above. The limit switch 21 is attached to a predetermined position on the side surface of the tip side of the boom 1. The main hoist rope 11 is passed through the through hole of the weight 23, and the weight 23 is arranged to be vertically movable on the main hoist rope 11 between the tip side of the boom 1 and the parent hook 13. Thus, the limit switch 21 is used as a return sensing type.

[0023] In addition, the overwinding prevention device B is electrically connected to the limit switch 21 and the controller of the main winch via the signal line 24 and is operatively connected to the controller. In this case, the signal line 24 (see FIG. 1) connected to the limit switch 21 is wired along the main boom M1, and extends toward the controller via the cord reel 15 on the proximal end side of the main boom M1 and is connected to the controller.

[0024] In this way, in the overwinding prevention device B, the wire rope 22 is suspended from the lower end of the operating pin of the limit switch 21 under the gravity from the weight 23. In this state, the gravity of the weight 23 acts on the operating pin of the limit switch 21 to pull the operating pin downward, and the limit switch 21 is in the off state. In the off state, no control signal is transmitted from the limit switch 21. Then, from this off state, when the main winch winds up the main winch rope 11 and the parent hook 13 moves upward, and the upper part of the parent hook 13 abuts on the weight 23 and pushes it upward, the wire rope 22 becomes slack and the operating pin of the limit switch 21 is released from the weight of the weight 23. The operating pin of the limit switch 21 moves upward by the biasing force of the coil spring, and the limit switch 21 becomes in the on state. Due to this on state, a control signal is transmitted from the limit switch 21 to the controller of the main winch, and the controller stops the winding of the main winch rope 11 by the main winch. Thus, overwinding of the main winch rope 11 is prevented, and collision between the parent hook 13 and the boom 1, and further, backward fall of the boom 1 are prevented.

[0025] As shown in FIG. 1, the parent hook miswinding prevention device A is installed on the front facing the main winch rope 11 on the lower side of the boom 1 and is configured to prevent incorrect winding of the main winch rope 11.

[0026] As shown in FIGS. 2 to 17, this parent hook miswinding prevention device A (hereinafter referred to as this device A) includes a pair of arms 3, a tension spring 4, a tension detector 5, and a cord 6.

[0027] A pair of arms 3 are arranged in parallel in the width direction and protrude on the front side facing the main winding rope 11 below the middle part in the vertical direction of the boom 1.

[0028] In this case, each of the pair of arms 3 is made of steel materials such as steel pipes, steel bars, and steel plates, and has a length extending slightly forward from the position of the main winding rope 11 suspended from the tip of the main boom M1. Here, the pair of arms 3 are formed by steel pipes with an appropriate diameter to a predetermined length from the front of the main boom M1 to a position slightly forward from the position of the main winding rope 11. And at the tip of these arms 3, pulleys 30 for passing the cable 6 are attached. Note that these pulleys 30 are rotatably attached to the tip of each arm 3 in the direction of stretching the cable 6 between the arms 3.

[0029] Also, in this case, each of the pair of arms 3 is attached via a mounting bracket 31 to the front of the boom 1 so as to be protrudable forward from the front of the boom 1 and foldable in parallel along this front as shown in FIGS. 8 to 13. Here, the mounting bracket 31 has a frame mounting portion 311 and an arm mounting portion 312. The frame mounting portion 311 is attachable to columnar frames M11 extending vertically on both left and right sides of the front of the main boom M1. It consists of a receiving bracket 311A having a substantially U-shaped cross section (in this case, a substantially semi-circular cross section) and a flat plate-shaped (in this case, the inner surface has a substantially semi-circular cross section) tightening bracket 311B fixed and connected by a plurality of bolts between both ends of the receiving bracket 311A. The arm mounting portion 312 is fixed to the side surface of the frame mounting portion 311, extends substantially at a right angle to the tightening bracket 311B (in other words, at a right angle to the frame M11), and includes a protruding direction mounting portion 312A formed of a tube into which one end of the arm 3 can be fitted, and a folding direction mounting portion 312B formed of a tube extending substantially parallel to the tightening bracket 311B (in other words, parallel to the frame M11) into which one end of the arm 3 can be fitted. Thread holes for bolts are formed on the circumferential surfaces of the protruding direction mounting portion 312A and the folding direction mounting portion 312B, respectively. Incidentally, each of these pair of arms 3 may be pivotally supported on the front of the boom via a mounting bracket and attached to be foldable on the front of the boom. In this case, the mounting bracket consists of a frame mounting portion and an arm mounting portion, and it is sufficient that the arm mounting portion can be rotated on the side surface of the frame mounting portion and fixed at a predetermined rotation angle.

[0030] Furthermore, in this case, an inter-arm holding member 33 for preventing the pulling together between the arms 3 due to the tension of a cable 6 described later is also provided between the pair of arms 3. The inter-arm holding member 33 is made of a steel material such as a steel pipe, a steel bar, or a steel plate, and is disposed and fixed between the arms 3. In this case, the inter-arm holding member 33 is made of a steel pipe, is bridged between the mounting brackets 31 of the arms 3, and is fixed to each mounting bracket 31. Incidentally, the inter-arm holding member 33 may be disposed between the arms 3 and directly fixed to each arm 3.

[0031] The tension spring 4 is provided on one of the pair of arms 3 and is for pulling the cable 6 stretched between the arms 3. In this case, the tension spring 4 consists of a tension coil spring (hereinafter referred to as the tension coil spring 4). This tension coil spring 4 is attached to a mounting portion 32 provided on the side surface facing outward in the middle portion in the longitudinal direction of the right arm 3 (the side surface opposite to the side surface facing the other (left) arm 3). In this case, the mounting portion 32 includes a protruding portion 321 having a bolt insertion hole protruding from the side surface of one arm 3, a bolt 322 passed through the bolt insertion hole of the protruding portion 321, and a nut 323 screwed onto the bolt 322. One end of the tension coil spring 4 is connected to the tip of the bolt 322 of the mounting portion 32, and the other end is directed toward the tip side of one arm 3 and is arranged in parallel with the right one of the arms 3.

[0032] The tension detector 5 is provided on the other of the pair of arms 3 and is electrically connected to the controller via the signal line L5. It is configured to sense the pulling force of the cable 6 and transmit a control signal to the controller to stop the winding of the main winding winch or the auxiliary winding winch, in this case the main winding rope 11 by the former.

[0033] In this case, the tension detector 5 consists of a limit switch (hereinafter referred to as the limit switch 5). This limit switch 5 is common with the limit switch 21 used in the aforementioned overwind prevention device B, and can be selectively used as a return sensing type or a tension sensing type according to the wiring method of the device. In the overwind prevention device B, the limit switch 21 is used as a return sensing type, while in this tension detector 5, this limit switch 5 is used as a tension sensing type. That is, this limit switch 5 is configured such that the operating pin is normally biased upward by the biasing force of the coil spring to be in an off state, and the operating pin is switched to an on state by being pulled downward by an external force (in this case, the pulling force by the rope 6). This limit switch 5 is fixed to the side surface facing outward in the middle of the length direction of the left arm 3 of the main body case (the side surface opposite to the side surface facing the other (right side) arm 3), and the operating pin in the main body case is arranged parallel to the other left arm 3 with the tip facing the tip side of the other arm 3. Thus, this limit switch 5 is used as a tension sensing type.

[0034] Also, in this case, the signal line L5 of the limit switch 5 may be wired along the main boom M1 and directly connected to the controller of the winch for the main winding. However, in this apparatus A, as described above, the crane C is equipped with overwind prevention devices for the main winding rope and the auxiliary winding rope. Using the signal line 24 connected between this overwind prevention device and the controller, the signal line L5 of the limit switch 5 is connected (branch-wired) to this signal line 24 and electrically connected to the controller. In this case, as shown in Fig. 15, the signal line 24 connected between the overwind prevention device B and the controller is disconnected at the position of the cord reel 15 on the base end side of the main boom M1. Each end of this disconnected signal line 24 is connected via a branch connection connector J to which the signal line L5 of the limit switch 5 is branch-distributed. Thus, the limit switch 5 is branch-wired to the circuit between the overwind prevention device and the controller, that is, incorporated into the circuit between the overwind prevention device and the controller and electrically connected to the controller. By connecting the signal line L5 of the limit switch 5, which serves as a tension detector, to the signal line 24 between the overwind prevention device and the controller via the connector J at the position of the cord reel 15 on the base end side of the main boom M1, the signal line L5 of the limit switch 5 can be made short and this signal line L5 does not get in the way.

[0035] The cable 6 has one end connected to the tension coil spring 4 and the other end operatively connected to the limit switch 5, and is elastically stretched between the pair of arms 3. In this case, the cable 6 is composed of a wire rope (hereinafter referred to as the wire rope 6), and has a length that is the sum of the length required to connect one end to the tension coil spring 4 and the length required to connect the other end to the operating pin of the limit switch 5 within the length between the pair of arms 3. This wire rope 6 is stretched between the tip portions of the respective arms 3 via the respective pulleys 30, the right end is connected to the tip of the tension coil spring 4 on the side surface of the right arm 3, and the left end is connected to the operating pin of the limit switch 5 on the side surface of the left arm 3 via a wire clip on the wire rope 6 side and a shackle on the operating pin side. Note that the tension state of this wire rope 6 between the pair of arms 3 can be adjusted by advancing and retracting the bolt 322 with respect to the nut 323 at the attachment portion 32 of the tension coil spring 4 of the right arm 3.

[0036] In this way, when performing a lifting operation with the reeving rope 12 and the sub-hook 14 of the crane C, the wire rope 6 between the respective arms 3 is arranged by the respective arms 3 between the boom 1 and the main hoist rope 11 that are lowered, and the main hoist rope 11 in a state where the main hook 13 is lowered to the lower side of the crane and fixed. When the main hoist winch or the reeving winch, in this case the former, winds up the main hoist rope 11 during the lifting operation, the slack of the main hoist rope 11 is reduced and the main hoist rope 11 is pulled toward the boom 1 side. Therefore, the pulling of the main hoist rope 11 is elastically received and suppressed by the wire rope 6, and based on the control signal sensed and transmitted by the limit switch 5 from the pulling force of the wire rope 6 pulled by the pulling of the main hoist rope 11 toward the boom 1 side, the main hoist winch or the reeving winch, in this case the former, stops winding up the main hoist rope 11 by the controller.

[0037] Fig. 16 shows an example of the use of this device A. Here, as an example of crane work, the operation of lifting a pile with the sub-hook 14 and inserting it into a hole dug in the ground is illustrated. In this case, when the pile is moved up and down by the vertical movement of the sub-hook 14, in order to prevent the unused main hook 13 from swinging back and forth and hitting the boom 1, damaging the boom frame or lattice, the main hook 13 is lowered below the crane C, a wire W is attached to the crane C (such as the slewing platform), this wire W is hung on the main hook 13, and is moderately tensioned to fix the main hook 13, thereby preventing the main hook 13 from swinging back and forth.

[0038] When using this device A, this device A is attached to the boom 1 of the crane C. This attachment is carried out by attaching a pair of arms 3 to the respective frames M11 on both the left and right sides of the front of the main boom M1 by means of mounting brackets 31, as shown in Figs. 2 to 7. In this case, the boom 1 of the crane C is laid down substantially horizontally, and two mounting brackets 31 are respectively wound with receiving brackets 311A from below the laid-down boom 1 at positions slightly above the fixing position of the main hook 13 on the respective frames M11 on both the left and right sides of the front of the main boom M1, and clamping brackets 311B are received from above the laid-down boom 1 and tightened to the both ends of the receiving bracket 311A with bolts for attachment. Then, one end of each arm 3 is inserted into the protruding direction mounting portion 312A of the arm mounting portion 312 of these mounting brackets 31, and bolts are tightened into the respective screw holes of the protruding direction mounting portion 312A to fix, so that each arm 3 protrudes downward at a right angle to the respective frames M11 from the respective frames M11 on the front of the main boom M1. And, if necessary, the tension state of the wire rope 6 between the pair of arms 3 is adjusted by advancing and retracting the bolt 322 with respect to the nut 323 at the attachment portion 32 of the tension coil spring 5 of one of the arms 3. At this time, the pulling together between the arms 3 due to the tension of the wire rope 6 is prevented by the arm-to-arm holding member 33.

[0039] Attach the device A in this way, raise the main boom M1 of the crane C, interpose the device A between the main boom M1 and the main hoist rope 11, and arrange the wire rope 6 close to the main hoist rope 11 by a pair of arms 3. In this state, perform the operation by the crane C. In this case, lift a pile with the sub-hook 14 and insert it into a hole excavated in the ground.

[0040] As shown in Fig. 16, during the operation of this crane C, if an accident occurs in which the operator of the crane C accidentally operates the main hoist winch and winds up the main hoist rope 11, at the time when the main hoist rope 11 is being wound up, the main hoist rope 11 is not in an overwind state, so the overwind prevention device B installed on the crane C does not operate, and mechanical detection by this overwind prevention device B cannot be performed. Therefore, conventionally, unless the operator stops winding the main hoist rope 11 with the main hoist winch, the winding up of the main hoist rope 11 continues. In this crane C, due to the installation of the device A, the winding of the main hoist rope 11 is mechanically and surely stopped safely.

[0041] That is, when the main hoist rope 11 fixed to the crane C is wound up, the main hoist rope 11 gradually becomes tense and is pulled and approaches toward the front of the main boom M1. When the main hoist rope 11 contacts and presses the wire rope 6 of the present device A, the main hoist rope 11 is elastically received by the wire rope 6 while being pressed by the main hoist rope 11, and due to the expansion and contraction action of the tension coil spring 4 at one end of the wire rope 6, the wire rope 6 is pulled in the swinging direction of the main hoist rope 11, that is, toward the front of the main boom M11. This pulling force is sensed by the limit switch 5 of the present device A, and a control signal is transmitted from this limit switch 5 to the controller of the winch for main hoisting. In this case, the control signal is transmitted from the signal line L5 of the limit switch 5 through the signal line 24 between the controller and the overwind prevention device connected by the connector J at the position of the cord reel 15 on the base end side of the main boom M1 to the controller. Then, based on this control signal, by the control of the controller, the drive of the winch for main hoisting is stopped, and the winding of the main hoist rope 11 by this winch is stopped. In this way, the pulling of the main hoist rope 11 toward the boom 1 side is stopped, the winding up of the main hoist rope 11 is stopped, and the miswinding of the parent hook 13 is prevented.

[0042] Thereby, it is possible to prevent the wire W from being cut due to excessive winding of the main hoist rope 11 as in the prior art, and the collision and destruction with the objects approaching the crane C due to the swing of the parent hook 13 before and after caused by the cutting of the wire W are prevented in advance. As a result, conventionally, when the pile is moved up and down by the vertical movement of the sub-hook 14, the parent hook 13 in the idle suspension that is not used swings back and forth and may collide violently with the boom 1, damaging the boom frame and the lattice. To prevent this, the parent hook 13 is lowered to below the crane C, the wire W is attached to the crane C, the wire W is hung on the parent hook 13, and the parent hook 13 is fixed by stretching it appropriately. This measure becomes effective.

[0043] When disassembling and transporting the crane C, as shown in FIGS. 8 to 13, the present device A can be folded onto the crane C and moved together with the crane C. To fold the present device A, first, the boom 1 of the crane C is laid down substantially horizontally, and the present device A is removed from the respective mounting brackets 31 of each frame M11 on both the left and right sides of the front of the main boom M1. In this case (see FIGS. 2 to 7), the bolts are loosened or removed from the respective screw holes of the protruding direction mounting portions 312A of the arm mounting portions 312 of each mounting bracket 31, the fixing of one end of each arm 3 is released, and each arm 3 is pulled out from each protruding direction mounting portion 312A. Then, one end of each arm 3 is inserted into each folding direction mounting portion 312B and fixed by tightening bolts into the respective screw holes, and each arm 3 is folded and arranged in parallel along each frame M11 on the front of the main boom M1. Thereby, the present device A is folded and mounted in parallel with the main boom M1, without protruding from the front of the main boom M1 and without causing any interference. By doing so, the present device A can be transported by the crane C together with the movement of the crane C. Also, by doing so, the present device A can be permanently installed without interfering with the crane C, and the present device A can be similarly used during the same lifting operation of the crane C.

[0044] As described above, in the present apparatus A, when performing a hanging operation using the supplementary winding rope 12 and the sub-hook 14, each wire rope 6 between the respective arms 3 is arranged by each arm 3 to be close to the main winding rope 11 between the boom 1 and the main winding rope 11 with the boom 1 and the main winding rope 11 lowered and the parent hook 13 fixed below the crane C. When the main winding rope 11 is wound up by the main winding winch during the hanging operation, the pulling of the main winding rope 11 toward the boom 1 side is elastically received by the wire rope 6 and suppressed, and based on the control signal sensed and transmitted by the limit switch 5 from the wire rope 6 pulled by the swing of the main winding rope 11, the controller stops the winding of the main winding rope by the main winding winch. Therefore, in the hanging operation using the crane C as described above, in order to prevent the pulling of the unused parent hook 13 toward the boom 1 side, even if the operator of the crane C accidentally operates the main winding winch and winds up the main winding rope 11, the winding of the main winding rope 11 can be mechanically and surely stopped safely. Therefore, according to the present apparatus A, it is possible to surely prevent the wire W from being cut due to overwinding of the main winding rope 11, and it is possible to prevent in advance the collision and destruction of the objects close to the crane C due to the swing of the parent hook 13 before and after the wire W is cut.

[0045] And in the present apparatus A, each of the pair of arms 3 is attached via a mounting bracket 31 to the front of the boom 1 so as to be able to project forward from the front of the boom 1 and fold along this front. By folding the present apparatus A along the front of the boom 1, the present apparatus A can be mounted on the boom 1 without protruding from the front of the boom 1 and without causing any interference, and the crane C can be disassembled and transported while the present apparatus A is mounted on the crane C. Also, by doing so, the present apparatus A can be always provided without interfering with the crane C, and the present apparatus A can be similarly used during the same hanging operation of the crane C.

[0046] In addition, in this device A, the tension detector consists of a limit switch 5, the tension spring consists of a tension coil spring 4, and the cable-like part consists of a wire rope 6. Since it is composed of these few devices and materials, the entire device A can have a simple structure, and the device A can be manufactured simply and at low cost.

[0047] Furthermore, in this device A, by utilizing the fact that the crane C is equipped with an overwind prevention device for the main hoist rope and the auxiliary hoist rope, and each overwind prevention device is electrically connected to the controller via a signal line 24, the limit switch 5 serving as the tension detector is connected to the controller by connecting the signal line L5 of this tension detector to the signal line 24 between each overwind prevention device and the controller via a branch wiring type connector J. Therefore, by sharing the signal line and the controller, the crane C can be easily equipped.

[0048] In this embodiment, a main winch is used to wind up the parent hook, and an auxiliary winch is used to wind up the child hook. However, conversely, an auxiliary winch may be used to wind up the parent hook, and a main winch may be used to wind up the child hook. Such a way of using winches can be seen, for example, in underground obstacle removal work or bucket excavation work. Usually, the main winch with a large load is installed on the front side close to the boom, and the auxiliary winch is installed on the rear side thereof. However, there are cases where the operation levers and brake pedals of the driver's seat are arranged in the order of the main winch and the auxiliary winch from the left, and there are also those with a different arrangement. Currently, the arrangements of the operation levers and brake pedals vary depending on the manufacturer. Also, usually, the winding up and winding down of the main winch rope and the auxiliary winch rope are performed by power operation, that is, by the winch. However, for example, when inserting a pile for pile driving cannot be done by power operation, it is lowered by the weight of the load, that is, by gravity operation of free fall. Such operations are often used, for example, in underground obstacle removal work or clam hole drilling work. In this case, the winding up is performed by the operation lever, but the winding down is performed by dropping the load by gravity. Therefore, the deceleration and stop of the drop are operated by the brake pedal. Since the operation of the brake pedal is performed by pressing the brake pedal with the foot, the position of the brake pedal is important for the driver in terms of operation, including the driver's convenience. However, the position of the brake pedal is fixed and cannot be changed. Therefore, according to the position of the brake pedal, the main winch rope is replaced with the auxiliary winch rope, and the auxiliary winch rope is replaced with the main winch rope. An auxiliary winch is used to wind up the parent hook, and a main winch is used to wind up the child hook. Note that the rotation speeds of the main winch and the auxiliary winch are the same. However, when the parent hook is loaded on either the main winch or the auxiliary winch, the number of times the wire rope is hung on the pulley increases, so the up and down movement of the parent hook becomes slower accordingly. Even when an auxiliary winch is used to wind up the parent hook and a main winch is used to wind up the child hook in this way, this device can be applied in the same manner as in the above embodiment and can achieve the same operational effects as in the above embodiment.

[0049] Also, in this embodiment, a general limit switch is used as the tension detector. However, any appropriate detector or sensor with a function similar to that of this limit switch can be selected and replaced as appropriate from various other detectors and sensors.

[0050] Also, in this embodiment, a tension coil spring is used as the tension spring. However, any appropriate spring member or spring mechanism with a function similar to that of this tension coil spring can be selected and replaced as appropriate from various other spring members and spring mechanisms.

[0051] Furthermore, in this embodiment, a wire rope is used in a cord shape. However, any appropriate cord-shaped or wire material with a function similar to that of this wire rope can be selected and replaced as appropriate.

Explanation of Reference Numerals

[0052] C Crane 1 Boom М1 Main Boom М11 Frame S1 Upper Boom 10 Base 101 Boom Point Sheave for Main Hoist 102 Boom Point Sheave for Auxiliary Hoist 11 Main Hoist Rope 12 Auxiliary Hoist Rope 13 Parent Hook 14 Child Hook 15 Cable Reel W Wire B Overwind Prevention Device 21 Overwind Detector (Limit Switch) 22 Weight Suspension Rope (Wire Rope) 23 Weight 24 Signal Line A Parent Hook Miswinding Prevention Device (This Device) 3 Arm 30 Pulley 31 Mounting Bracket 311 Frame Mounting Portion 311A Receiving Bracket 311B Clamping fitting 312 Arm mounting part 312A Protrusion direction mounting part 312B Folding direction mounting part 32 Mounting part 321 Protrusion 322 Bolt 323 Nut 33 Arm-to-arm holding member 4 Tension spring (tension coil spring) 5 Tension detector (limit switch) L5 Signal line 6 Cable (wire rope)

Claims

1. A boom having at least a boom point sheave for main winding and a boom point sheave for auxiliary winding on the tip side, supported on a base so as to be able to undulate, and driven by a driving device installed on the base; A main winding rope that is fed out from one of a main winding winch or an auxiliary winding winch installed on the base and wound around the boom point sheave for main winding on the tip side of the boom, and fed out from the other, and wound around the boom point sheave for auxiliary winding An auxiliary winding rope, a parent hook connected to the tip of the main winding rope and suspended on the tip side of the boom, and a child hook connected to the tip of the auxiliary winding rope and suspended on the tip side of the boom; A controller that controls the operations of the driving device, the main winding winch, and the auxiliary winding winch, and is equipped with a crane that raises and lowers the parent hook and the child hook by feeding out and winding up the main winding rope by one of the main winding winch or the auxiliary winding winch, and feeding out and winding up the auxiliary winding rope by the other. A parent hook miswinding prevention device for preventing miswinding of the parent hook, A pair of arms protruding in parallel in the width direction on the front surface facing the main winding rope on the lower side of the boom; A cord stretched between the pair of arms; A tension spring provided on one of the pair of arms and connected to one end of the cord for pulling the cord, and provided on the other, operatively connected to the other end of the cord and electrically connected to the controller via a signal line, and sensing the pulling force of the cord And a tension detector that transmits a control signal to the controller to stop the winding of the main winding rope by the main winding winch or the auxiliary winding winch; Comprising; During the hanging operation by the auxiliary winding rope and the child hook, the cord between the respective arms is arranged between the boom and the main winding rope in a state where the boom and the main winding rope are lowered and the parent hook is lowered to the lower side of the crane and fixed by the respective arms. When the main hoist rope is wound up by the main hoist winch or the auxiliary hoist winch during the hanging operation, the pulling of the main hoist rope toward the boom side is elastically received and pressed in a cord-like manner, and the pulling force from the cord-like body pulled by the pulling of the main hoist rope toward the boom side is sensed by the tension detector and transmitted. Based on the control signal, the controller stops the winding of the main hoist rope by the main hoist winch or the auxiliary hoist winch. The parent hook miswinding prevention device is characterized by the above.

2. The pair of arms are respectively attached to the front of the boom via mounting brackets so as to be protrudable forward from the front of the boom and foldable along the front. The parent hook miswinding prevention device according to claim 1.

3. The tension detector is a limit switch. The parent hook miswinding prevention device according to claim 1 or 2.

4. The tension spring is a tension coil spring. The parent hook miswinding prevention device according to any one of claims 1 to 3.

5. The cord-like body is a wire rope. The parent hook miswinding prevention device according to any one of claims 1 to 4.

6. The crane is equipped with overwind prevention devices for the main hoist rope and the auxiliary hoist rope. Each of the overwind prevention devices is electrically connected to the controller via a signal line. The tension detector is connected to the controller by connecting the signal line of the tension detector to the signal line between each of the overwind prevention devices and the controller via a branch wiring connector. The parent hook miswinding prevention device according to any one of claims 1 to 5.

Images