JPH0686278B2 - Crane load detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a load detection device for a crane, and is particularly suitable for a double-link type retractable crane in which one end of a hoisting rope is not folded back by a lifting tool. The present invention relates to a detection device.

[Conventional technology]

Conventional double-link type retractable cranes, especially for cranes in which one end of the hoisting rope is not folded back by a hoisting device, as a device for detecting the weight of the suspended load The force generated on the folded sheave shaft is detected via the sheave (JP-A-60-77092).

Alternatively, a movable sheave is provided between two sheaves, and the movable sheave is connected to a load detector to detect the load (well known.
Page 63 of the conventional technology collection "Crane" (published by the Japan Patent Office on June 30, 1982).

[Problems to be Solved by the Invention]

The hanging load of a crane is generally detected at the end of the rope or the sheave shaft through which the rope passes. However, in the double-ring type retractable crane, the winding angle of the rope wound around the sheave changes as the working radius of the lifting operation changes. In order to make the detection value of the suspension load the same regardless of the working radius, the configuration described in the section of the related art is adopted.

The structure of this prior art requires a sheave dedicated to detecting a hanging load, is uneconomical, and has a problem that the number of times of bending the rope is increased and the life of the rope is shortened.

An object of the present invention is to be able to detect a hanging load without increasing the number of sheaves.

[Means for Solving the Problems]

The above-mentioned object is to detect a hoisting load of a sheave 4 coaxially arranged on a connecting pin 3 of a first member 1 and a second member 2 whose angles relatively change, as shown in FIG. The sheave 4 is supported by a first link 7 rotatably mounted on the first member 1 in the vertical direction and a second link 8 rotatably mounted on the second member in the vertical direction. , The first link 7 or the second link 8 is detected by detecting the axial force.

At the other end of the first member 1 there is a winding drum or sheave 5,
The other end of the member 2 has a sheave 6. A line connecting the rotation center 7a of the first link 7 and the shaft center 3 of the sheave 4 is substantially parallel to the winding cylinder or the sheave 5 and the rope 9 hung on the sheave 4. The rotation center 8a of the second link 8 and the shaft center 3 of the sheave 4
The line connecting and is substantially parallel to the rope 9 hung on the sheaves 4 and 6.

For example, the first member 1 is a mast and the second member 2 is a tension boom. Alternatively, the first member is a tension boom and the second member is a top boom.

[Work]

In FIG. 1, the resultant force T acts on the sheave shaft by the tension P of the rope 9 wound around the sheave 4. If the wrapping angle changes, the resultant force T changes, but the resultant force T that supports the sheave shaft by the links 7 and 8 parallel to the rope direction is decomposed in the axial direction of each link, and the component force of each is equal to the rope tension. P. Since this relationship is not related to the change in the winding angle of the rope, the rope tension, that is, the suspension load can be known by detecting the axial force acting on the link 7 or the link 8.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side view of a double link type retractable crane to which the present invention is applied. Reference numeral 15 is a swivel frame installed on the traveling frame 11 so as to be freely swivelable, and 16 is a mast fixed to the swivel frame 15. Reference numeral 17 is a main boom, one end of which is pin-connected to the swing frame 15. 18 is a tension boom, one end of which is pin-connected to the top of the mast 16. Reference numeral 19 denotes a top boom, which is pin-connected to the tip of the main boom 17 and the tip of the tension boom 18. Reference numeral 20 is a retracting device for rotating the main boom 17 in the vertical direction, which is installed in the middle of the mast 16. 21 is a counterweight,
It is pin-coupled to the top of the mast 21 and urges the main mast 17 upward.

Reference numeral 30 denotes a winch winding cylinder installed on the swivel frame 15.
The rope 31 is a sheave 33 and a tension boom provided on the same axis as the connecting pin between the mast 16 and the tension boom 18.
A sheave 34 provided on the same axis as the connecting pin between the 18 and the top boom 19 and a sheave 35 at the tip of the top boom 19 are sequentially passed to reach the hook 36 of the lifting tool.

The above configuration is known.

A load detection device 40 is installed around the sheave 34 at the connecting portion between the tension boom 18 and the top boom 19. Hereinafter, the configuration of the load detection device 40 will be described in detail with reference to FIGS. 3 and 4.

The tension boom 18 and the top boom 19 are connected by a pin 41 so as to be vertically rotatable. The sheaves 34, 34 are installed on both sides of the pin 41 in the axial direction. This is because there are two ropes 31 unwound from the winding drum 30. Sheave 34
The sheave shaft 42 is located on the axis of the connecting pin 41. The sheave shaft 42 has links 43 and 44, connecting pins 45 and 46, and bracket 4.
It is supported by the tension boom 18 and the top boom 19 via 7,48, respectively. The links 43 and 44 can be rotated in the vertical direction. The line connecting the connecting pin 45 and the sheave shaft 42 is parallel to the rope 31 between the sheave 33 and the sheave 34. The wire connecting the sheave shaft 42 and the connecting pin 46 is the sheave 34 and the sheave 35.
It is parallel to the rope 31 between. The shaft hole 43a of the link 43 supporting the sheave shaft 42 is formed in the axial direction of the link 43 (the rope 31
It is a long hole in the direction parallel to.

A U-shaped receiving seat 51 is provided inside the U-shaped link 43. The seat 51 is rotatably attached to the sheave shaft 42. A load detector 52 is arranged between the bottom of the U-shaped link 43 and the U-shaped receiving seat 51 in the axial direction of the link 43.
The length of the long hole 43a of the link 43 is determined based on the expansion / contraction amount of the load detector 52. The load detector 52 outputs a voltage proportional to the load.

In such a configuration, due to the load applied to the rope 31,
Since the sheave shaft 42 moves with respect to the connecting pin 45, the load detector 52 can detect the axial force of the link 43, that is, the load of the rope 31.

Further, although the angle of the top boom 19 with respect to the tension boom 34 is changed by the operation of the retracting device 20, the links 43, 4
Since 4 is parallel to the arrangement direction of the rope 31 in its vicinity,
The direction of the load acting on the sheave 34 is always constant. Therefore, the rope load can always be detected correctly.

According to this, since the sheave 34 is an existing one, it is economical and the rope has a long life.

A second embodiment shown in FIGS. 5 and 6 will be described. Link 43b,
The connecting pin 45a that supports 43b is an eccentric shaft. That is, the center C ₁ of the shaft hole of the brackets 47a, 47a supporting the eccentric shaft 45a is located below the center C ₂ of the shaft hole of the link 43b supported by the eccentric shaft 45a. An arm 55 is fixed upward at the center of the eccentric shaft 45a, and its tip is in contact with the detector of the load detector 52. The load detector 52 is fixed to a bracket 56 provided upright on the tension boom 18. 57 is a load detector
This is a tension spring for preventing the detector of 52 from falling off.

According to this configuration, since the eccentric shaft 45a is used, the load applied to the load detector 52 can be reduced and the load detector 52 can be reduced in size.

The embodiment of FIG. 7 is a third embodiment in which the eccentric shaft 45a of the second embodiment is replaced with a lever 61. One end of the lever 61 is rotatably attached to the tension boom 18 with a pin 62,
The other end is in contact with the load detector 52. Link 43b has pin 62
It is rotatably attached by a pin 45b to a lever 61 between the load detector 52 and the load detector 52.

As the axial force acting on the link, another known detector can be used. For example, a strain gauge is provided on the shaft 45, the shear load acting on the shaft 45 is measured, and the axial force is detected.

In the embodiment shown in FIG. 8, the load detecting device 40 is provided at the sheave 33 on the top of the mast 16. A link 44 supporting the sheave 33 is rotatably installed on the tension boom 18 with a pin 46. The other link 43 (43b) that supports the sheave 33
Is a pin on the bracket 71 installed near the top of the mast 16.
It is rotatably installed at 45. The link 44 is parallel to the rope 31 between the sheave 33 and the sheave 34, and the link 43 is parallel to the rope 31 between the winding drum 30 and the sheave 33. Others are the same as those in FIGS. 3 to 7.

In this case, one boom of the pair of booms whose angles relatively change is a mast, but is equivalent to the boom. The winding drum 20 is also equivalent to the sheave.

It should be noted that FIG. 8 illustrates the load detection device 40, and thus members around it are omitted.

In FIG. 8, when the suspending tool 36 is brought close to the revolving frame 15 side, the tension boom 18 rises, so the link 43 (43
Since the angle of the link 44 with respect to b) becomes large (close to a straight line), the accuracy of the detected load is poor. Therefore, as shown in FIG. 2, it is preferable to install it between the tension boom 18 and the top boom 19.

Although each of the above embodiments has been described with respect to the double-link type crane, it can be used for other cranes as long as the configuration of FIG. 1 is obtained.

〔The invention's effect〕

According to the present invention, since the rope tension can be accurately detected from the portion where the rope winding angle changes, it is economical, the number of times of bending of the rope is small, and it is advantageous for the rope life.

[Brief description of drawings]

FIG. 1 is a force line diagram for explaining the contents of the present invention, FIG. 2 is a side view of a double link type retracting crane according to an embodiment of the present invention, and FIG. 3 is a load detection according to an embodiment of the present invention. FIG. 4 is a side view of the device, FIG. 4 is a cross sectional view of FIG. 3, FIG. 5 is a side view of a load detecting device according to another embodiment of the present invention, and FIG. 6 is a cross sectional view of FIG. FIG. 8 is a side view of a load detecting device according to an embodiment of the present invention, and FIG. 8 is a side view of a main part of a double link type retractable crane according to another embodiment of the present invention. 1 ... first member, 2 ... second member, 4,5,6 ... sheave, 7 ... first link, 8 ... second link, 9 ...
Rope, 16 …… Mast, 17 …… Main boom, 18 …… Tension boom, 19 …… Top boom, 20 …… Retractor, 30 …… Winch reel, 31 …… Rope, 33,34,35…
… Sheave, 36 …… Lifting equipment, 40 …… Load detection device, 41 …… Connecting pin, 42… Sheave shaft, 43,44… Link, 45a… Eccentric shaft, 52… Load detector

Claims (5)

[Claims] 1. A first member having a first sheave composed of a winding cylinder or a sheave, and a second member rotatably installed on the first member and having a second sheave, A third sheave installed on the axis of a pin connecting the first member and the second member, and means for rotating the second member relative to the first member , Is rotatably installed on the first member, has the third sheave installed at the tip thereof, and is substantially attached to a rope supported by the first sheave and the third sheave. A first link installed in parallel and a rotatably installed on the second member, the third sheave being installed at the tip, and the third sheave and the second sheave. A second link installed substantially parallel to the rope supported on the first link; A load detector for detecting the axial force of at least one link of the second link, the load detection apparatus for a crane comprising a. 2. The load detecting device for a crane according to claim 1, wherein the first member is attached to a mast having a winding drum so as to be vertically rotatable, and the first sheave is the mast. And a load detecting device for a crane, which is installed at a connection point between the second member and the first member, and the second sheave is installed at a tip of the second member. 3. The load detecting device for a crane according to claim 1, wherein the first link is rotatably installed on the first member, and is installed toward the pin. A fourth link rotatably installed on the pin and installed toward the third link, wherein the load detector is installed between the third link and the fourth link. Is a crane load detection device. 4. The load detection device for a crane according to claim 1, wherein means for converting the axial force of the first link into a rotational force is provided between the first link and the first member. ,
The load detector of the crane, wherein the load detector detects the rotational force of the means for converting into the rotational force. 5. The load detection device for a crane according to claim 1, wherein the load detector detects a load generated on a shaft installed on the first member to support the first link. There is a crane load detection device.