JPS6117393Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wire strain gauge load cell (hereinafter referred to as load cell) type weighing machine.

When a load cell is used as a weighing machine by being incorporated into a mechanism, the load applied to the load cell must be aligned with the axis of the load cell strain body and in a vertical direction. This is because when a lateral load acts on the load cell, the amount of expansion and contraction of the strain-generating body becomes undefined, making it impossible to perform accurate weighing.

Various systems have been developed in consideration of the above points, and FIG. 3 shows an example of the Roberval system using a parallel link mechanism. In this method,
A receiver 2 of a weighted plate 1 is supported by a fixed frame 5 by a pair of upper and lower parallel members 3 and 4, and one load cell 8 is attached between brackets 6 and 7 provided on the fixed frame 5 and the receiver 2. . The load cell has a very small amount of displacement, about 0.2mm at full scale.
In order to attach the receiver 2 and the fixed frame 5 to the parallel members 3 and 4, bending joints made of an elastic body are used to avoid problems caused by wear and rust on the pins. However, depending on the position of the weighing plate 1 on which the object to be weighed is placed, either a tension or compression force acts on the upper and lower parallel members 3 and 4.There is no problem with tension, but in the case of compression, the member There are problems such as 3 or 4 buckling or bending.

The purpose of this proposal is to solve the above-mentioned conventional problems.The point of application of the load is placed at an eccentric position with respect to the load plate holder, so that only the force in the tensile direction is always applied to the two parallel members. This is how it was done.

The present invention will be explained in detail below using the illustrated embodiments.

In Fig. 1, 10 is an inverted F-shaped fixed frame, 11
shows a crank-shaped weighted plate holder, and its fixed frame 10
The upper and lower parts of the load plate support 11 are connected by a pair of parallel members 12 and 13 that protrude in opposite directions, and in the case of the figure, a steel band. Both ends of each steel band and each part 10, 11 are attached to each other by fixing plates 14 and bolts 15 so that there is no play between them. Also fixed frame 1
A load cell 16 is fixed to the lower surface of the upper horizontal portion 10a of the load cell 10, and the load cell 16 is connected to a vertical shaft 17 attached to the lower horizontal portion 11a of the weight plate support via a rotatable pin 18. The weight plate 19 is L-shaped and is fixed by bolts 20 at right angles to the side surface of the vertical portion 11b of the receiver 11.

When a measurement load W is applied to the load plate 19, a tensile load acts on the load cell 16 via the vertical shaft 17. In this case, even if the point of application X of the load W moves on the load plate 19, a rotational moment is generated in the receiver 11 about the pin 18, and the load acting on the load cell 16 is reduced only by changing the tension of the bands 12 and 13. Always constant.

Further, even when the measurement load W acts on the load cell and causes vertical elongation of the load cell 16 and the vertical axis 17, the tensile direction of the load cell 16 is displaced to an almost negligible extent as described below.

As mentioned above, the load cell 16 has an elongation of about 0.2 mm at its rated full scale. On the other hand, vertical axis 1
7. Since the elongation of other parts can be suppressed to about 0.5 mm, the overall elongation is about 0.7 mm.

Now scale band 12,1 as shown in Figure 2
If the length of 3 is AB = CD = 50 mm, and the distance between the upper and lower steel bands 12 and 13 is BD = 300 mm, the vertical displacement of BB' and DD' is a = 0.7 mm, so the horizontal displacement of BB' and DD' is If the quantity is b, then b=50−√50 ² −0.7 ² =0.0049. The vertical component force due to this inclination is approximately the measured load W
, and can be completely ignored. Note that E indicates the point of application of the load W, and F indicates the central axis of the pin 18.

As mentioned above, since the parallel members 12 and 13 can be considered as a mere tension pair for preventing rotation, it is not necessary to adopt a roberval structure. Therefore, as the parallel member, other than the steel band as described above, any material that is highly flexible and has high tensile strength can be used.

Incidentally, twisting can be solved by using two steel bands each on the upper and lower sides.

The present invention always applies force only in the tensile direction to the pair of upper and lower steel bands as described above, so it is durable without problems such as buckling or bending.
Also, since only the vertical force is applied to the load cell and almost all of the measured vertical load is applied to the load cell,
High precision. Furthermore, since the bolt etc. is fixed so that there is no play at the attachment point of the steel band, there is an effect that the attachment screw does not become distorted due to wear, rust, etc.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the displacement of a parallel member with respect to a measured load, and FIG. 3 is a front view of a conventional example. 10 is a fixed frame, 11 is a weight plate support, 12 and 13 are parallel members, 16 is a load cell, and 19 is a weight plate.

Claims (1)

[Scope of utility model registration request] A substantially inverted F-shaped fixed frame 10 and a crank-shaped weighted plate holder 11 are placed facing each other, and a load cell 1 is placed between horizontal parts 10a and 11a of each vertically opposing frame.
6, and connect the upper and lower parts of both frames 10 and 11 with parallel steel bands 12 and 13 so that there is no play in mounting with the bolts 15, and the weight plate 19 is attached to the side surface of the weight plate holder 11. This is a load cell type weighing machine that is installed in a machine and configured so that the upper and lower parallel steel bands always receive only the force in the tensile direction.