JPS6222548Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a crane scale that is attached to a cargo handling machine such as a crane to measure the weight of an object to be weighed.

Conventionally, this type of crane scale has been constructed by suspending a tension type load cell with hanging fittings above and below the crane hook, or by separating the sheave part and the hook part of the hook, and incorporating a tension type load cell between them. There are generally known devices that measure the weight of objects to be weighed.

By the way, in the above-mentioned crane scale, a load cell is installed between the crane hook and the object to be weighed, or between the sheave part of the hook and the hook part. The distance between the cranes becomes longer and the lifting height of the crane decreases, making it necessary to restrict the movement range of the crane and making the building higher in order to secure the necessary lifting height. Overloading the load cell may cause a load cell rupture accident. If this occurs, there is a risk that the suspended object to be weighed will fall, so the load cell used must have a capacity larger than the crane's capacity or be equipped with metal fittings to prevent it from falling. It had drawbacks such as:

The present invention was made to eliminate the above-mentioned drawbacks of conventional crane scales used by being attached to cargo handling equipment such as cranes, and its purpose is to:
By interposing a beam fixed at both ends with strain sensors that detect shear strain in a direction approximately 45 degrees from the neutral axis between the bracket provided on the side plate supporting the hook and the sheave shaft, the shear strain of the beam can be reduced. The purpose of this method is to use a low-height load cell to reduce the lifting height of the crane, and to prevent the object to be weighed from falling by supporting the side plate with the sheave shaft when the beam fixed at both ends breaks.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIGS. 1 and 2, a hook 1 for suspending an object to be weighed (not shown) is fixed to a trunnion 3 by a nut 2, and the trunnion 3 is attached at both ends 3a, 3b to the lower part of side plates 4a, 4b. It is rotatably supported.

On the other hand, sheaves 6a and 6b suspended and supported by wire ropes 5a and 5b are rotatably attached to a sheave shaft 7, and the sheave shaft 7 has both ends 7a,
7b are loosely fitted into vertically elongated holes 8a, 8b provided in the side plates 4a, 4b.

A bracket 9 provided at the top of the side plate 4a
a and the end 7a of the sheave shaft 7, and between the bracket 9b provided on the top of the other side plate 4b and the other end 7b of the sheave shaft 7, there are load cells 11 described below, respectively. , 11 are interposed.

Both of the load cells 11, 11 have the side plates 4a, 4b as shown in FIGS. 3 and 4.
A base portion 11a for attachment to the brackets 9a and 9b, a beam portion 11b having ends 11'b and 11'b supported by the base portion 11a, and a sheave provided approximately at the center of the beam portion 11b. axis 7
The bearing part 11c has a shaft hole 11'c.

Between the base portion 11a and the beam portion 11b,
A slit 11d is provided, and the beam portion 11b forms a both-end fixed beam fixed to the base portion 11a at both ends 11'b, 11'b.

On the side wall surfaces 12a and 12b of the beam portion 11b,
Shaft hole 1 of sheave shaft 7 provided in the bearing portion 11c
On both sides of the main axis (not shown) passing through the center of 1'c,
on the neutral axis (not shown) of the beam portion 11b, and in a direction that is approximately 45 degrees from the neutral axis;
Strain gauges R1, R2, which detect 45 degree shear strain
...、R8 is glued.

Of the strain gauges R1, R2,..., R8, the strain gauges R1 and R2 and the strain gauges R3 and R4 are respectively bonded at positions approximately equidistant from the main axis on the side wall surface 12a of the beam portion 11b. Meanwhile, strain gauges R5 and R6
Strain gauges R7 and R8 are each bonded to the other side wall surface 12b of the beam portion 11b at positions approximately equidistant from the main axis.

As shown in Figure 5, the strain gauges R1, R2,...R8 are strain gauges R1 and R7, strain gauges R4 and R6, strain gauges R3 and R5, and strain gauges R2 and R8, respectively. Connected to form each side.

As mentioned above, the strain gauge R1 is attached to the beam portion 11b.
Load cells 11, 11 with R2,..., R8 glued
The hook 1 is inserted by inserting bolts (not shown) into the bolt holes 13, 13 provided at both ends of the base portion 11a, as shown in FIGS. 1 and 2.
The load cells 11, 11 are attached to the brackets 9a, 9a of the side plates 4a, 4b, respectively, and the bearing portions 11b, 11b of these load cells 11,
is supported.

If the crane scale is configured as above,
The weight of the object to be weighed acting on hook 1 is
and acts on the side plates 4a, 4b via the trunnion 3.

The weight of the object to be weighed acting on the side plates 4a, 4b is transferred to the sheave shaft 7 via the brackets 9a, 9b.
acts on the load cells 11, 11 supported by the load cells 11, 11, and applies shear strain to the beam portions 11b of these load cells 11, 11.

This shear strain is detected by strain gauges R1, R2,..., R8.

By the way, the sheave shaft 7 is connected to the load cell 11,
If it is shifted from the center of the beam portion 11b of No. 11,
As shown in FIG. 6, shear forces F ₁ and F ₂ of different magnitude are generated in response to the load W acting on the beam portion 11b from the sheave shaft 7, but the strain gauges R1, R2, . . . R8 is connected to form a Wheatstone bridge circuit as shown in Figure 5, so the sum of shear forces F ₁ and F ₂ is detected, and the Wheatstone bridge circuit can accurately detect the weight of

In addition, in this invention, strain gauges R1, R2,
..., both ends 11'b of the beam part 11b to which R8 is glued,
11'b is not directly fixed to the brackets 9a, 9b, and a slit 11d is provided between the beam portion 11b and the base 11a, so that the load cell 11,
The hysteresis caused by the deterioration of the load characteristics of No. 11 can be greatly improved.

Furthermore, the load cells 11, 11 are connected to the beam portion 11.
Since the weight of the object to be weighed is detected by detecting the shear strain of b, the distance between the sheave shaft 7 and trunnion 3 is smaller and the lifting height of the crane is also larger compared to conventional crane scales. .

Note that the present invention can be widely applied to weighing machines of cargo handling machines having a sheave shaft.

As is clear from the detailed description above, the present invention is a load cell with fixed beams at both ends attached to the outside of the side plate of a crane falling block. Insert,
Furthermore, since the sheave shaft is loosely fitted into a vertically elongated hole provided in the side plate, the load cell can be mounted without changing the length between the sheave shaft center and the crane hook. Furthermore, even if the load cell is damaged due to overload, the sheave shaft is supported by the elongated hole in the side plate, so the risk of the object to be weighed falling together with the hook can be eliminated.

[Brief explanation of the drawing]

1 and 2 are respectively a front view and a side view of the load detection section of an embodiment of the crane scale according to the present invention, and FIGS. 3 and 4 are respectively the loads of an embodiment of the crane scale according to the present invention. A front view and a side view of a load cell attached to the detection section, FIG. 5 is a circuit diagram of a Wheatstone bridge circuit for load detection, and FIG. 6 is a diagram of the principle of load detection. 1...Hook, 4a, 4b...Side plate, 5a, 5
b... Wire, 6a, 6b... Sheave, 7... Sheave shaft, 9a, 9b... Bracket, 11... Load cell, 11a... Base part, 11b... Beam part, 11'b... End part, 11c...Bearing part, 1
1'c...Shaft hole.

Claims (1)

[Scope of utility model registration request] A shaft hole is provided in the center of the beam fixed at both ends in a horizontal direction and in a direction orthogonal to the longitudinal direction of the beam, and on the neutral axis of the beam fixed at both ends, shear strain in a direction making 45 degrees with the neutral axis is detected. In order to do this, strain detection sensors are glued on the neutral axes of the four sides (front, rear, left and right) of the beam fixed at both ends in a direction that makes an angle of 45 degrees with the neutral axis, and both ends of the beam fixed at both ends are attached to the beam fixed at both ends. It is equipped with a load cell that is connected to a parallel mounting base with a slit-like gap, and the base is attached to a bracket provided on a side plate that rotatably supports both ends of a shaft member that supports the crane hook. At the same time, a sheave shaft of the crane is inserted into the shaft hole, and both ends of the sheave shaft are loosely fitted into vertically elongated holes provided in the side plate to act in the radial direction of the shaft hole. A crane scale characterized in that force is detected by the strain detection sensor.