JPH11292473A - Back tension device for luffing jib - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the distance between an aerial sheave block and a fixed sheave block by winding a back tension wire rope delivered from a winch arranged on a swivel base from a groove located on the boom center side of multiple sheaves. SOLUTION: An aerial sheave block 24 is constituted of multiple sheaves 29, 30 located symmetrically with the boom axis and having two parallel sheave center axes 27, 28 nearly perpendicular to the boom axis. A main winding wire rope 15 delivered from the drum 18 of a main winding winch 13 arranged on a swivel base 2 is wound on the right groove of the upper sheave 29 on the boom axis left side of the aerial sheave block 24, it is folded and wound on the uppermost sheave 33 of a fixed sheave block 26, then it is wound on the upper sheave 30 on the boom axis right side of the aerial sheave block 24. The wire rope 15 is finally fixed to the connection section 39 of the fixed block 26 via a rope end 38 and a load cell 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back tension device for a luffing jib mounted on a tip of a telescopic boom of a crane having a telescopic boom, and more particularly to a structure of an aerial sheave block in the back tension device. is there.

[0002]

2. Description of the Related Art A luffing jib is used mainly when a crane operation is required at a high place and with a relatively large working radius. The back-tension device adjusts the undulation angle and holds the posture at the required undulation angle. And
A hanging load wire rope extending from a winch arranged on the swivel side that supports the telescopic boom is hung down from a top sheave provided at the tip of a roughing jib, and a required crane operation is performed using the hanging load wire rope.

[0003] In addition, the above-mentioned back tension device generally attaches an aerial sheave block to a jib support member that is pulled out from a distal end portion of the luffing jib to a telescopic boom side through a mast provided upright at a base end of the luffing jib. Connected. After wrapping the back tension wire rope fed from the winch arranged on the swivel side around the aerial sheave block, it wraps around a fixed sheave block that is swingably connected to the base end side of the base boom. A back tension wire is wrapped between the aerial sheave block and the fixed sheave block so as to have a predetermined number, and is connected to the fixed sheave block. Then, the back tension wire rope is wound by the winch arranged on the swivel side.
The unwinding adjusts the luffing angle of the luffing jib and maintains the posture at the predetermined luffing angle via the jib support member.

[0004] As described above, the back tension wire rope is used in a multi-stage state in order to reduce the rope tension. The method shown in FIG. 5 is known as a prior art as a method of multiplying such a back tension wire rope in multiple stages. FIG. 5 shows the base boom 3b and the swivel base 2 viewed from the back. The winch 13 is disposed on the swivel base 2 and is connected to the jib support member 6 drawn out to the telescopic boom 3 via a mast. The arrangement of a movable aerial sheave block 14 and a fixed sheave block 16 swingably connected to a base end side of a base boom 3b is shown. Back tension wire 15 unreeled from winch 13
Is wound around an aerial sheave block 14 having a plurality of sheaves, and a fixed sheave block 16 having a plurality of sheaves.
After being looped between the aerial sheave block 14 and the fixed sheave block 16 so as to have a predetermined number, the tip thereof is connected to the fixed sheave block connecting portion 19.
It is connected to. FIG. 6 is a diagram showing a wire rope hung around in the state shown in FIG.

[0005] As shown in Fig. 5, the drum 18 of the winch 13 is arranged such that the center in the width direction coincides with the center of the boom. This is because when the crane performs a boom operation or a jib operation other than the luffing jib operation, the wire rope pulled out from the winch 13 is wrapped around the sheave at the center of the boom tip in the boom width direction, so that the fleet angle is reduced. This is because the above arrangement is necessary due to the relationship. Winch 1 as well known
In order for the wire wound around the third drum 18 to be wound up in multiple layers in an orderly manner, its fleet angle needs to be less than a specified value. When the fleet angle exceeds the limit, the wire rope winds around the winch drum. Since the wire wound around the drum 18 is wound while moving left and right over the entire width of the drum, it is convenient for the fleet angle to arrange the center of the drum 18 in the width direction so as to coincide with the center of the boom. is there. The jib support member 6 has been drawn out along the center of the boom, and the aerial sheave block 14 also moves along the center of the boom.

However, when such a conventional method is employed, the position where the back tension wire 15a fed from the winch 13 is wound around the sheave groove of the aerial sheave block 14 deviates from the center of the boom by the radius of the sheave. There was a problem. For this reason, as shown in FIG. 5, when the back tension wire rope 15a is first hung in the right groove of the sheave of the aerial sheave block 14, if it is pulled out from the left end of the drum 18, a fleet angle is obtained. Is in the worst case. Therefore, it is necessary to determine the minimum distance between the aerial sheave block 14 and the fixed sheave block 16 during the luffing jib operation based on the worst fleet angle state. This led to the problem that the working area of the luffing jib was reduced. That is, when the tilting angle of the luffing jib in the state where the telescopic boom is short is small, the distance between the aerial sheave block 14 and the fixed sheave block 16 becomes small, so that the working range of the luffing jib is determined by the possible distance described above. is there. In addition, there is a problem that the width dimension of the winding portion of the drum 18 is restricted if the working range of the roughing jib is secured only in a necessary range. The above problem is not a serious problem when the luffing jib is small and the winch drum width is small, but becomes a significant problem when the mobile crane becomes very large and the winch drum width becomes wide.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention proposes a luffing jib back tension device which can widen the luffing jib working range and can make the winch drum wider.

[0008]

According to the present invention, the following configuration is employed as specific means for solving the above-mentioned problems.

In the first aspect of the present invention, the base end of the telescopic boom is mounted on the swivel base such that the base end of the telescopic boom is raised and lowered. A luffing jib is attached, and a jib support member having one end connected to a tip end of the luffing jib is pulled out toward the telescopic boom through a mast erected at a base end of the luffing jib or a distal end of the telescopic boom. Connecting the jib support member to an aerial sheave block composed of a plurality of sheaves, and wrapping a back tension wire rope fed from a winch arranged on the swivel side around the aerial sheave block, to thereby provide a base end of the base boom. Around a fixed sheave block consisting of a plurality of sheaves that are swingably connected to the After wrapping the back tension wire between the middle sheave block and the fixed sheave block, the back tension wire is connected to a suitable place near the fixed sheave block or to the aerial sheave block, and the back tension wire rope is wound and unwound by the winch. In the luffing jib back tension device in which the luffing jib is raised and lowered and held at a predetermined raised and lowered position, the aerial sheave block is provided with two pieces which are substantially orthogonal to and parallel to a boom axis positioned symmetrically with respect to the boom axis. It is constituted by a plurality of sheaves having a sheave center axis, and a back tension wire rope fed out from a winch arranged on the swivel side is wound around a groove located on the boom center side of the sheave of the aerial sheave block. .

According to a second invention of the present application, in the luffing jib back tension device according to the first invention,
A plurality of sheaves of the aerial sheave block are alternately arranged.

According to a third invention of the present application, in the luffing jib back tension device according to the first invention,
The aerial sheave block is characterized in that the wire rope centers of the grooves on the boom center side of the plurality of sheaves are arranged so as to substantially contact the same plane.

According to the present invention, the following effects can be obtained by adopting such a configuration. In the first invention of the present application, the aerial sheave block is constituted by a plurality of sheaves having two sheave center axes that are symmetrically positioned with respect to the boom axis and that are substantially orthogonal to and parallel to the boom axis. Since the back tension wire rope fed out from the winch arranged on the table side is wrapped around the groove located on the center side of the boom of the sheave of the aerial sheave block, a point of contact with the sheave of the aerial sheave block of the back tension wire fed out of the winch. Becomes almost coincident with the boom axis. Thus, the left and right angles at the end of the drum width at which the maximum fleet angle is reached can be made substantially the same as the fleet angle of the back tension wire fed out over the entire width of the winch drum.

Here, as in the second invention of the present application, when a plurality of sheaves of the above-mentioned aerial sheave block are arranged so as to be alternately overlapped, the sheave is pulled out from a winch and looped between the aerial sheave block and the fixed sheave block. The back tension wires can secure an interval in the vertical direction.

Further, as in the third invention of the present application, when the wire rope centers of the grooves on the boom center side of the plurality of sheaves of the aerial sheave block are arranged so as to be substantially in contact with the same plane, the sheave is extended from the winch to the aerial sheave block. The fleet angle of the back tension wire can be minimized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described based on preferred embodiments. FIG. 1 shows a mobile crane with a luffing jib equipped with a back tension device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a vehicle as a traveling base, and 2 denotes a vehicle that can turn on the vehicle 1. Is a telescopic boom having a base end (base boom 3b) connected to the swivel base 2 so that the base end (base boom 3b) can be raised and lowered in the vertical direction, and having a tip end 3a.
The telescopic boom 3 is driven up and down by an up / down hydraulic cylinder 10.

Reference numeral 5 denotes a luffing jib mounted on the distal end 3a of the telescopic boom so as to be able to move up and down.
As shown in FIG. 1, the luffing jib 5 has a base end connected to the front side of the boom tip end 3 a via a jib support 4 so as to be able to undulate and form a base end of the luffing jib 5, A middle jib connected to the tip of the base jib, and a top jib connected to the tip of the middle jib to form the tip of the luffing jib 5 and having a top sheave for crane work at the tip. .

In this embodiment, the luffing jib 5 is composed of the base jib, the middle jib, and the top jib as described above. However, the configuration of the luffing jib 5 is not limited to this. And a top jib to form a luffing jib 5. Thereafter, one or more middle jibs are provided between the base jib and the top jib according to conditions such as a work radius or a work head required for work. Just connect them.

As shown in FIG. 1, the luffing jib 5 having such a structure is mounted on the distal end portion 3a of the telescopic boom 3 via a jib support 4 so as to be able to move up and down. A jib support member 6 whose one end is connected to the distal end 5a of the luffing jib 5 is connected to the telescopic boom 3 via a first mast 8 and a second mast 9 erected at the base end of the luffing jib 5. It is pulled out to the upper surface side of. The jib support member 6 includes a bending tension rod 11 that connects the distal end of the first mast 8 and the distal end of the second mast 9, and a tension rod 1 that is connected to the distal end of the second mast.
7, a tension rope 20 connected to the tension rod 17, a tension rope 21 connected to the distal end of the first mast 8, and a tension rope 21 connected to the tension rope 21 provided corresponding to the middle jib. A tension rod is provided corresponding to the rod 7 and the top jib and connects a tip end of the top jib and the tension rod 7. The jib support members 6 are arranged in a pair at predetermined intervals in the jib width direction.

An aerial sheave block 24 is connected to the ends of the tension ropes 20, 20 of the pair of jib support members 6, 6. Above air sheave block 2
A main winding winch 13 (corresponding to a “winch” in the claims) disposed between the swivel 2 and the fixed sheave block 26 fixed to the base end of the base bob 3b. The main winding wire rope (corresponding to "back tension wire rope" in the claims) extending from the multi-stage is wound. The above structure constitutes a back tension device, and the main winding winch 13 is provided.
The luffing jib 5 is appropriately driven up and down by the winding and rewinding, and the luffing jib 5 is held at a required undulating angle position by stopping and holding the main winding winch 13. In addition, the main winding wire rope 1 constituting a part of the back tension device is used.
The connection structure 5 is the gist of the present invention. Therefore, the connection structure and various components attached thereto will be described later in detail.

Mast sheaves are provided at the ends of the first mast 8 and the second mast 9, respectively, so that when the crane works using the luffing jib 5,
An auxiliary winding wire rope 25 extending from the auxiliary winding winch 12 disposed on the side of the swivel 2 is suspended through the top sheave at the end of the luffing jib 5 via the respective mast sheaves. Perform the required crane work using the suspension hooks provided in

FIG. 2 is a view taken in the direction of the arrow A in FIG. 1 and shows the connection structure of the main winding wire rope 15 and various components attached thereto. Numeral 24 denotes an aerial sheave block, which is located symmetrically with respect to the boom axis, and has two sheave center axes 2 which are substantially perpendicular to and parallel to the boom axis.
It comprises a plurality of sheaves 29, 30 having 7,28. FIG. 3 is a view of the aerial sheave 24 as viewed from the direction of arrows BB. With respect to the boom axis of the aerial sheave block 24, the sheaves 29a and 29b on the left and the sheaves 30a and 30b on the right are alternately arranged. Further, the wire rope centers of the grooves on the boom center side of the plurality of sheaves of the aerial sheave block 24 are arranged so as to substantially contact the same plane. Reference numeral 31 is a support for indicating the sheave center axes 27 and 28.

The main winding wire rope 15 drawn out from the drum 18 of the main winding winch 13 arranged on the swivel 2 in FIG. 2 is wound around the right side groove of the upper sheave 29a on the left side of the boom axis of the aerial sheave block 24. You. The fixed sheave block 26 is folded back and wrapped around the top sheave 33a. Next, the aerial sheave block 24 is wound around the upper sheave 30a on the right side of the boom axis. The main winding wire rope wrapped around the aerial sheave block 24 and the fixed sheave block 26 in such a manner as to hang eight wires finally reaches the connecting portion 39 of the fixed sheave block 26 via the cable end 38 and the load cell 37. Be linked. FIG. 4 shows a diagram of the back tension device wound around a wire rope.
The tension rope 20, which is a jib support member drawn out toward the telescopic boom side, is connected to a connecting portion 36 at the distal end of the aerial sheave block 24.

As described above, the main winding wire rope 15a unwound from the drum 18 of the main winding winch 13
Is looped around the center of the aerial sheave block 24.
In other words, since the wire is wound around a position that coincides with the boom axis, the maximum value of the fleet angle of the main winding wire rope fed out while being swung right and left over the entire width of the drum can be made equal to the left and right angles. For this reason, the distance between the aerial sheave block and the fixed sheave block can be reduced with respect to the same specified value of the fleet angle.

In the above embodiment, the case where the sheave block of the aerial sheave block is constituted by two sheaves is described as an example. Further, the width dimension of the aerial sheave block orthogonal to the boom axis is increased, so that the attachment width of the back tension wire can be increased. As a result, the rotation of the wire rope can be reduced, so that the aerial sheave block can be prevented from tilting obliquely.

[0025]

As described above, the luffing jib back tension device of the present invention can shorten the distance between the aerial sheave block and the fixed sheave block as compared with the conventional luffing jib. Work range of work can be expanded. Also,
If the minimum distance between the conventional one, the aerial sheave block and the fixed sheave block is the same, it is possible to increase the width of the winding portion of the drum.

[Brief description of the drawings]

FIG. 1 is an overall view showing a preferred embodiment of a back tension device for a luffing jib according to the present invention.

FIG. 2 is a view taken in the direction of arrow A in FIG. 1;

FIG. 3 is a view as seen in the direction of arrow B in FIG. 2;

FIG. 4 is a diagram showing a wire tension loop of the back tension device according to the present invention.

FIG. 5 is a view showing a conventional luffing jib back tension device.

FIG. 6 is a diagram of a conventional back tension device wound around a wire rope.

[Explanation of symbols]

 Reference Signs List 1 vehicle 2 turntable 3 telescopic boom 3b base boom 4 jib support 5 roughing jib 6 jib support member 7, 11, 17 tension rod 8 first mast 9 second mast 20, 21, tension rope 12 auxiliary winding winch 13, main winding winch 14, 24 Aerial sheave block 15, 15a Main winding wire rope 16, 26 Fixed sheave block 18 Drum 25 Auxiliary winding wire rope 27, 28, 32 Sheave center axis 29, 30, 33 Sheave 29a, 29b, 30a, 30b Sheave 31, 34 Support

Claims (3)

[Claims] 1. A luffing jib is attached to a distal end portion of a telescopic boom whose base end is freely raised and lowered with respect to a swivel base, in a direction along the undulating surface of the telescopic boom, and A jib support member, one end of which is connected to the distal end of the luffing jib, is pulled out to the telescopic boom side through a mast erected at the base end of the luffing jib or the distal end of the telescopic boom, and the jib support member is pulled out. A back tension wire rope, which is connected to an aerial sheave block composed of a plurality of sheaves and is fed from a winch arranged on the swivel side, is wrapped around the aerial sheave block, and then swings toward the base end of the base boom. Loop around a fixed sheave block consisting of a plurality of sheaves that are connected as much as possible, and Loop around the back tension wire between the lock and the fixed sheave block, and connected to the appropriate place or the air sheave block near the fixed sheave block,
In the back tension device of the luffing jib, which raises and lowers the luffing jib by winding and rewinding the back tension wire rope by the winch, the aerial sheave block is positioned with respect to the boom axis. The aerial sheave block is composed of a plurality of sheaves symmetrically located and having two sheave center axes substantially perpendicular to and parallel to the boom axis and fed out from a winch disposed on the swivel side. A back tension device for a luffing jib, which is wound around a groove located on the center side of the boom of the sheave. 2. The luffing jib back tension device according to claim 1, wherein a plurality of sheaves of the aerial sheave block are alternately arranged. 3. The back tension device for a luffing jib according to claim 2, wherein the wire rope centers of the grooves on the boom center side of the plurality of sheaves of the aerial sheave block are disposed so as to substantially contact the same plane. Luffing jib back tension device.