JP2527639Y2 - Weighing conveyor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing conveyor in which a belt conveyor is supported by a pair of Roberval type load cells.

[0002]

2. Description of the Related Art A Roberval type load cell is also called a parallel gram type load cell. For a small object to be weighed, even if the position where a load acts is not affected by a moment, an error is caused in the weighing value. Does not occur. However, when the object to be weighed is relatively large and the load is large, such as a weighing device using a plurality of load cells, the load is applied and the pedestal of the object to be weighed is bent. The error due to the moment occurs because the distance of is short. Therefore, conventionally, a weighing device has been known in which a moment is not generated when the mounting table is bent (for example, see Japanese Patent Publication No. 3-3892 and Japanese Utility Model Publication No. 3-4903). An example of this type of weighing device is shown in FIG.

[0003] In FIG. 4, a platform 50 on which an object is to be weighed is supported by a pair of Roberval type load cells 51, 51 which are separated from each other in the longitudinal direction A1 of the platform 50. Each load cell 51 has a through hole 51a penetrating in the longitudinal direction A1, and as is well known, even if the position of the load changes in a horizontal lateral direction B1 orthogonal to the longitudinal direction A1, the detected value of the load cell 51 It is arranged so that no error due to the moment occurs. One end 52 of the table 50 in the longitudinal direction A1 is rotatably supported around a horizontal axis 53,
On the other hand, the other end 54 is supported by the load cell 51 via a sphere 55. By supporting in this way, even if the load 50 is bent by the load, the other end 54 of the load 50 slides on the load cell 51 via the sphere 55. , No moment in the direction of arrow C is generated. In addition, this structure also has an advantage that the structure is simplified as compared with a case where the other end 54 of the mounting table 50 is supported using a link mechanism.

[0004]

[Problem to be solved by the present invention]
Instead, in a weighing conveyor in which a belt conveyor is supported by a pair of load cells, when an object to be weighed is conveyed onto the belt conveyor, the vibration of the belt conveyor is transmitted to the load cell, and the flexure element of the load cell vibrates. Therefore, the responsiveness is reduced. In particular, in this type of weighing conveyor, since the objects to be weighed are often conveyed one after another, it is important to shorten the weighing cycle time. Becomes

[0005] This invention has been made in view of the above conventional problems, can be removed weighing errors due to flexure of the belt conveyor with a simple structure, yet, vibration of the belt conveyor
An object of the present invention is to provide a weighing conveyor that absorbs movement and has excellent responsiveness.

[0006]

In order to achieve the above-mentioned object, the present invention is directed to a belt conveyor which loads a load cell at an upstream end where an object to be weighed is carried in the conveying direction.
Supported rotatably about a horizontal axis in the orthogonal direction ,
On the other hand, at the downstream end where the object to be weighed is carried out, it is supported via a vibration-proof rubber which absorbs the vibration and horizontal displacement of the belt conveyor with respect to the load cell.

[0007]

According to this invention, since the downstream end of the belt conveyor is supported via the vibration-proof rubber, the vibration of the belt conveyor is absorbed by the vibration-proof rubber. Also, even if the belt conveyor is displaced in the horizontal direction due to bending,
Since the vibration isolating rubber itself is distorted in the horizontal direction, almost no moment is generated. Furthermore, the object to be weighed is carried in and
Even if a shock load is applied, the vertical
The displacement in the direction is not as great as the difference.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a pair of load cells 2 having a roberval mechanism are fixed to a base 1. The load cell 2 has a known structure, for example, a through hole 2b.
A strain gauge (not shown) is provided on the surface of the flexure element 2a having These load cells 2, 2 are arranged apart from each other in the transport direction A of the belt conveyor 3, and support the frame 3a of the belt conveyor 3 via the first and second supports 4, 5. ing. Each of the above load cells 2
Is arranged such that the through hole 2b of the flexure element 2a penetrates in the transport direction A. Therefore, as is well known, the position of the load changes in a horizontal lateral direction B orthogonal to the transport direction A. However, no error due to the moment occurs in the detected value of the load cell 2.

On each of the load cells 2,
Beams 6, 7 long in the B direction are fixed. The first and second supports 4 and 5 are fastened to both ends of the beams 6 and 7, respectively.

The first support 4 is provided at the upstream end 3b in the transport direction A, and has an insertion hole 4a shaped like an eyebolt and through which the horizontal shaft 8 is inserted. The horizontal shaft 8 is provided with a first bracket 9A fixed to the insertion hole 4a of the first support 4 and the frame 3a of the belt conveyor 3.
Through the insertion hole 9a. Thus, the belt conveyor 3 is rotatably supported around the horizontal shaft 8 at the upstream end 3b in the transport direction, as shown in FIG.

In FIG. 1, a second support 5 is provided at a downstream end 3c in the transport direction A, has a pair of male screws 5c protruding upward and downward, respectively, and has a beam 7 and a second It is fastened to the second bracket 9B. As shown in FIG. 3A, the second support 5 has, for example, a columnar vibration-proof rubber 5a at the center. Dish-shaped rubber supports 5 are provided on the upper and lower end surfaces of the vibration isolating rubber 5a, respectively.
b is fixed. The male screw 5c is provided on each of the rubber supports 5b so as to project vertically. Thus, as shown in FIG. 2, the belt conveyor 3 is at the downstream end 3c.
Are supported via anti-vibration rubber 5a.

Next, the operation of the above configuration will be described. When the object to be weighed is conveyed onto the belt conveyor 3, the belt conveyor 3 swings up and down. Waiting for the vertical swing to attenuate, the pair of load cells 2 output a weighing value. An arithmetic unit (not shown) calculates the weight of the object to be weighed by multiplying a sensitivity coefficient preset for each load cell 2 based on the two weighed values. afterwards,
The object to be weighed is discharged in the transport direction A, and the next object to be weighed is transported onto the belt conveyor 3. Thus, the objects to be weighed are weighed one after another.

In the above configuration, when an object to be weighed is conveyed onto the belt conveyor 3 and a load is applied, the frame 3a of the belt conveyor 3 slightly bends in a state where it is concave upward. Along with this, the first belt conveyor 3
In addition, the mounting pitch P1 of the second supports 4 and 5 is slightly reduced, so that the mounting pitch P2 of the first and second supports 4 and 5 in the load cell 2 is shorter.

Here, the belt conveyor 3 is made of a vibration-proof rubber 5a.
As shown in FIG. 3 (b), the vibration isolating rubber 5a is slightly compressed up and down, and is also deformed by generating shear strain in the horizontal direction as shown in FIG. 3 (b). the difference of the pitch P1, P2, i.e., pairs load cell 2
Of the belt conveyor 3 along the direction A is absorbed. Therefore, the horizontal force F acting on the load cell 2 is
Since it becomes extremely small in proportion to the amount of distortion of the vibration isolating rubber 5a, the moment M acting on the load cell 2 also becomes extremely small. As a result, no error due to the moment M occurs in the load cell 2. That is, the belt conveyor 3
Even if the frame 3a is bent, little weighing error occurs.

The vibration isolating rubber 5a absorbs vibrations generated when the object is conveyed onto the belt conveyor 3. Therefore, since the vibration is attenuated as soon as possible, the responsiveness of the weighing conveyor that requires a high responsiveness is improved. As a result, the weighing cycle time is shortened, and the objects to be conveyed can be measured one after another.

The upstream end 3 of the belt conveyor 3
It is conceivable that b is supported by the vibration isolating rubber 5a, while the downstream end 3c is rotatably supported. However, in this case, when an object to be weighed moves onto the belt conveyor 3, an impact load whose load increases with time acts on the vibration isolating rubber 5a disposed at the upstream end 3b. Therefore, when the object to be weighed is carried in, the vibration isolating rubber 5a is greatly shrunk by the impact load, so that the displacement in the vertical direction becomes large, so that the carrying state becomes unstable. Therefore, disturbance is mixed in the output of the load cell, and as a result, the accuracy of the measurement is reduced.

In contrast, the weighing conveyor rotatably supports the belt conveyor 3 at the upstream end 3b via the horizontal shaft 8 or the like. Since no significant vertical change occurs, there is no possibility that the accuracy of the measurement is reduced.

Further, since the downstream end portion 3c of the belt conveyor 3 is supported by the vibration isolating rubber 5a, the weighing conveyor has a simple structure as compared with the case where a conventional link mechanism is used.

In the above embodiment, the flexure element 2a constituting the load cell 2 has been described as an integral type. However, in the present invention, it is needless to say that the flexure element may be composed of a plurality of links. Nor.

[0020]

As described above, according to the present invention, since one end of the belt conveyor is supported via the vibration-proof rubber, the vibration of the belt conveyor is absorbed by the vibration-proof rubber. Further, even if the belt conveyor is bent, the vibration isolating rubber itself is distorted in the horizontal direction, so that almost no moment is generated. Therefore, even with a simple structure, there is almost no error caused by the bending of the belt conveyor. In particular, the responsiveness of the weighing conveyor, which requires quick responsiveness, is improved, and the weighing cycle time is shortened. Furthermore, since the downstream end, not the upstream end of the belt conveyor, is supported by the vibration-proof rubber, the vertical displacement does not increase so much.
There is little weighing error due to the disturbance, and therefore, there is no possibility that the accuracy of weighing is reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a weighing conveyor showing one embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a cross-sectional view of a second support provided with an anti-vibration rubber.

FIG. 4 is a partially broken perspective view showing a conventional weighing device.

[Explanation of symbols]

2: Load cell, 3: Belt conveyor, 5a: Anti-vibration rubber, 8: Horizontal axis, A: Transport direction, B: Horizontal direction perpendicular to.

Claims (1)

(57) [Scope of request for utility model registration] 1. A belt conveyor is supported by a pair of load cells separated from each other in a carrying direction for carrying an object to be weighed ,
Each load cell is equipped with a roberval mechanism that does not cause an error due to a moment in the detected value of the load cell even if the position of the load changes in a horizontal lateral direction orthogonal to the transport direction of the belt conveyor, and transports the object to be weighed. A weighing conveyor for weighing while the belt conveyor is rotatably supported around a horizontal axis in a direction orthogonal to the transport direction at an upstream end where the objects to be weighed are loaded ; A weighing conveyor supported at a downstream end where the weighing object is carried out via a vibration-proof rubber that absorbs vibration and horizontal displacement of the belt conveyor with respect to the load cell.