JPH025382Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a platform weighing device having a plurality of sets of load detection sections each consisting of a strain gauge type load cell.

[Prior art]

In general, platform scale devices are used to weigh items that are large in size and weight;
There are various types ranging from about 30 kg to about 5 tons. In this type of platform weighing device, the area of the weighing pan in contact with the object to be weighed is large;
It is necessary to support the weighing pan by disposing a load detecting section consisting of a plurality of strain gauge type load cells at predetermined locations on the weighing pan. In this case, the end of the load cell of each load detection part is supported by the underframe, but if this underframe bends during measurement and the mounting angle of the load cell changes, a measurement error will occur. In order to increase mechanical strength, the underframe must be made of thick steel with high rigidity to ensure a sturdy structure.Conventional platform weighing devices are therefore heavy, and as a result, as shown below. There was a drawback.

Because they cannot be easily carried, they are inconvenient to handle during manufacturing or maintenance.
Work efficiency is low, and it is not easy for the user to change the installation location.

Manufacturing costs such as material costs and welding costs are high.

It is difficult to make the device thinner.

In order to solve the above-mentioned drawbacks and to reduce the weight, cost, and thickness of a platform weighing device, the present applicant has developed a weighing device described in Japanese Patent Application Laid-Open No. 59-3321. In this weighing device, as shown in Fig. 4A, flat plate-shaped load cells 2 are connected and attached to at least three spaced apart locations on a support member 1 arranged horizontally, and each load cell 2 is equipped with two spaced apart load cells. strain gauges 3, 3 are provided, and a load point B located on the vertical line A at the center between the strain gauges 3, 3 and support legs 4 are provided above and below each load cell 2. However, this weighing device still had the following problems.

In other words, as mentioned above, the purpose of platform scale devices is to weigh heavy objects, so they are often installed, for example, on the ground within a factory premises or on a concrete floor inside a building. Generally, there are many places where the surface is extremely uneven. On the other hand, the support legs 4 of the platform weighing device need to have a certain amount of ground contact area because it is necessary to reliably support the heavy object to be weighed in a place where the bearing capacity of the ground is low, such as the ground. In this case, if the support leg 4 is in contact with the ground at a point C spaced apart by a distance l from the center vertical line A between the strain gauges 3 and 3, as shown in FIG _.・L (W ₁ is the load applied to load point B) acts and bends the support member 1, which changes the angle of the load cell 2 with respect to the vertical line A, resulting in a measurement error. .

In view of the above-mentioned circumstances, the purpose of this invention is to provide a platform weighing device that is lighter in weight, less expensive, and thinner, and which has fewer measurement errors even in installation locations with severe unevenness.

[Means for solving problems]

This idea is based on a platform weighing device that has a plurality of load detection units that detect the load applied to one end of a load cell using a strain gauge installed on the load cell. a plurality of pairs of elongated plate-shaped support members having;
and a connecting member that interconnects the proximal ends of the plurality of pairs of support members, and the other end of each of the load cells is supported by each tip of each of the pairs of support members. It is said that

[Effect]

Even when each support member bends in response to the unevenness of the installation location, each load detection part is supported by the support members arranged in parallel, so it is held horizontally. loads are applied to each load detection section from the vertical direction.

〔Example〕

Embodiments of this invention will be described below with reference to the drawings.

1 to 3 are diagrams showing the configuration of an embodiment of this invention, in which FIG. 1 is a perspective view, FIG. 2 is a cross-sectional view taken along the - line of FIG. 1, and FIG. FIG. In these figures, 5, . The sensor is made of a metal suitable for strain detection, and is formed into a flat strip shape or a strip shape with a notch that makes it more susceptible to concentrated stress. One end of a bracket 7 is fastened to the upper surface of one end of each load cell 2 via a spacer 6 with a bolt 8a and a nut 8b. Further, a member 9 having a recess formed on the upper surface is attached to the upper surface of the other end of each bracket 7, and a support ball 10 is placed in the recess of each member 9. Further, a weighing plate 12 is placed on each support ball 10 via a member 11 having the same shape as the member 9. Thereby, the load of the object to be weighed placed on the weighing pan 12 is applied to the load point B (see FIG. 3) where each support ball 10 and each member 9 are in contact with each other.

On the other hand, in the figure, reference numerals 15 and 16 are flexible long plate-shaped support members arranged parallel to each other and spaced apart from each other vertically, and reference numeral 17 is four pairs of support members 15 and 1.
This is a connecting member that connects the respective proximal end portions of 6 to each other.
In this case, each support member pair 15, 16 is connected to the connecting member 1.
The base ends of each support member pair 15, 16 are connected to a bolt 19a and a nut 19b via a liner 18.
They are each tightened and fixed to the connecting member 17 by means of screws. A spacer 20 and each of the load cells 2 described above are provided between the tips of each pair of support members 15 and 16.
A liner 21 is arranged on the upper surface of the tip of each support member 15, and one end of a spacer 22 and a bracket 23 are arranged on the lower surface of the tip of each support member 16, and these are connected to the bolt. 24a
and are each tightened and fixed by nuts 24b. As a result, the other end portion of each load cell 2 is supported by each support member pair 15, 16 in a state where it is sandwiched from above and below. Further, a support leg 4 is attached to the other end of each bracket 23, respectively. In this case, the load point B and the support legs 4 mentioned above are arranged so as to be located on the vertical line A at the center between the two strain gauges 3, 3 (see FIG. 3).

Here, the external dimensions of the supporting members 15 and 16 mentioned above will be considered with reference to FIG. 4B. First, the vertical distance between the supporting members 15 and 16 is a, the width dimension is each b, the thickness dimension is each h, the length dimension excluding the part in contact with other members is L ₁ , and the Young's modulus is E
Then, the buckling limit load of each support member 15, 16 is
F _K is F _K =4・π ²・E・I/L ₁ ² =π ²・E・b・h ³ /3・L
₁ ² ... (1) Also, the frictional force acting between the ground and the support leg 4
If F ₃ is ignored and the compressive force acting on the support member 15 is F ₁ , then W ₁・l=a・F ₁ ... (2) ∴F ₁ =W ₁・l/a ... (3 ) Here, in order to satisfy F _K > F ₁ , Therefore, the thickness dimension h of the supporting members 15 and 16
It is sufficient to satisfy the above equation (4).

In addition, when the direction of the moment W ₁ ·l is opposite, the tension acting on the supporting members 15 and 16
It is sufficient that F ₂ is within the compressive force F ₁ and that the allowable stress σ satisfies the following equation (5).

σ<W ₁・l/a・b・h … (5) Here, when the frictional force F ₃ is taken into account, the mechanical strength of the supporting members 15 and 16 is as shown in (4) above.
It is sufficient that the strength is even lower than the strength obtained by conditional expression (5).

Thus, according to the embodiment described above, the above
Support member 1 with external dimensions that satisfy conditional expressions (4) and (5)
By using the support members 15 and 16, buckling-resistant support members 15 and 16 can be constructed using the minimum necessary material, thereby making it possible to reduce weight, cost, and thickness. Furthermore, as shown in FIG. 5, when weighing an object to be weighed M by installing it in a highly uneven installation location, the support members 15 and 16 may not be properly adjusted due to insufficient adjustment of the support legs 4. Even when bent due to unevenness, each load detection section 5 is held horizontally by an action similar to the so-called Roberval's balance mechanism, so the angle of the load cell 2 with respect to the vertical line A is Variations are prevented, which allows weighing errors to be minimized.

Next, modifications of each part of the above-described embodiment will be described. First, FIG. 6 is a diagram showing a modification of the load cell portion. In this figure, 30 is a double beam type load cell having a through hole 30a penetrating in the horizontal direction, and two strain gauges 3 are provided on each of the upper and lower surfaces. One end of this load cell 30 is a free joint 3 in which the upper and lower ends of a rubber material 32 are adhesively sandwiched between metal plates 33, 33.
4 to the weighing plate 12, and the other end is fixed to the support members 15 and 16 in a state where they are sandwiched from above and below. In this case, the weighing plate 12 and the load cell 30 are not separated, making it convenient to carry.

Note that the load cells applied to the platform scale device of the present invention are not limited to those shown in FIGS. 3 and 6,
For example, a shear type load cell, a compression type load cell, etc. may of course be used.

FIGS. 7 and 8 are views showing modified examples of the support member. In FIG. 7, members 35 and 36 whose central portions are U-shaped in cross section are attached to supporting members 15 and 16, respectively, and spacers 20
A portion of the connecting member 17 near the attachment portion where there is no bent portion becomes a strain-generating portion. Further, in FIG. 8, curved recesses 15a and 16a are shown in the vicinity of the portions of the supporting members 15 and 16 fixed to the connecting member 17 and the portions where the spacer 20 and the load cell 2 are fixed, respectively.
It is a structure in which each of these is formed. According to such a structure, it is possible to obtain appropriate flexure against unevenness of the installation location, and to improve buckling strength.

Note that a plurality of pairs of long plate-shaped support members 15, 16
They do not necessarily have to be separated, and may be formed integrally as shown in FIG. 11, which facilitates assembly. In addition, in the embodiments shown in FIGS. 1, 2, and 3, a recess is provided to connect the top surface of the other end of the bracket 7 attached to the top surface of one end of the load cell 2 via the spacer 6 to the weighing pan. The members 9, 11 and the support ball 10 were used, but the sixth
A connecting member shown in the figure or a connecting member consisting of a self-joint such as a pivot, a blade and a blade holder, a bearing and a backing plate, etc. may be used. In this case, when a load is applied to the weighing pan 12, the distance between the plurality of connecting members is reduced by bending the load cell, but the element that shrinks in the weighing pan 12 completely fixes the connection with the weighing pan 12. As a result, the fastening portion may become misaligned, causing phenomena that impede accuracy, such as hysteresis of the load cell and changes in the zero point. For this reason, the connecting members were made into free joints for the purpose of escaping the shortening of the distance between the connecting members. In addition, by using a free joint as the connecting member, it is possible to block the bending moment and torsional moment that occur in the load cell when a load is placed on the weighing pan 12, and each load cell only has a vertical load component. Since it can be transmitted, accuracy can also be improved from this fact.

Furthermore, in the present embodiment, the leg axis center is located vertically below the load point of each load cell passing through the center of the connecting member, but although this is the most preferable condition, it is not allowed by equations (4) and (5). Of course, there is no problem even if the perpendicular to the load point and the axis of the leg axis deviate within the range.

Next, another embodiment of this invention will be described. First, in Fig. 9 A and B, 39 is the member 4.
0, 41, 42 are overlapped and tightened with bolts 44, and grooves 40a, 41a, 41b, and 42a having the same cross-sectional shape as members 15, 16 are formed on the surfaces of each member 40, 41, 42 that contact each other. are formed with two grooves each, and these grooves 40
Support members 15 and 16 are inserted into horizontally penetrating through holes formed by a, 41a, 41b, and 42a, respectively. Then, the lengths of the supporting members 15, 16 are adjusted by loosening the bolts 44, and after the desired length is set, the supporting members 15, 16 are fixed to each other by loosening the bolts 44 again.

According to such a configuration, it is possible to freely adjust the position of the load detection unit 5 according to the dimensions of the weighing pan 12, and thereby, it is possible to support various length dimensions according to the dimensions of the weighing pan 12. Since there is no need to prepare the members 15 and 16, manufacturing costs can be reduced.

Next, FIG. 10 shows a modification of the other embodiment of the present invention shown in FIGS. 16a and 16b,
The support members 15a and 15b and the support members 16a and 16b are connected by bolts 46 and plates 47, respectively. Insertion holes into which bolts 46 are inserted are formed at a plurality of predetermined locations along the longitudinal direction of each support member 15a, 15b, 16a, and 16b, and any one of these insertion holes is selected. and bolt 46
By inserting and fixing the support member 15,
It is possible to adjust the length dimension of 16.

[Effect of idea]

As explained above, according to this invention, in a platform weighing device that has a plurality of load detection units that detect a load applied to one end of a load cell using a strain gauge provided on the load cell, the units are vertically spaced apart from each other. A plurality of pairs of flexible elongated plate-shaped support members arranged in parallel and a connecting member that interconnects base end portions of the plurality of pairs of support members are provided, and each of the pairs of support members The other end of each load cell is supported by each tip of the load cell, which not only makes it lighter, less expensive, and thinner, but also allows each support member to flex to accommodate the unevenness of the installation location. Even when soldering, each load detection part is held horizontally, so that the load of the object to be weighed acts on each load detection part from the vertical direction, making it possible to minimize measurement errors. If an adjustment mechanism is provided to adjust the distance between each load detection part and the connection member, there will be no need to prepare support members of various lengths depending on the dimensions of the weighing pan, which will improve manufacturing efficiency. The effect of further reducing costs can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the configuration of an embodiment of this invention, Fig. 2 is a sectional view taken along the - line of Fig. 1, and Fig. 3 is a sectional view taken along the line -
The figure is a partially enlarged sectional view of FIG. 2, FIG. 4A is a partial sectional view for explaining the operation of the conventional weighing device,
Figure B is a partial sectional view for explaining the operation of the part corresponding to Figure 4A of an embodiment of this invention, and Figure 5 is a side view for explaining the overall operation of an embodiment of this invention. 6 is a partial sectional view showing the structure of a modified example of the load cell portion of the same embodiment. FIGS. 7 and 8 are partial sectional views showing the structure of a modified example of the support member of the same embodiment. Figures 9A and 9B are diagrams showing the configuration of another embodiment of this invention, in which Figure 9A is a perspective view showing the overall configuration, and Figure 9B is a diagram showing the configuration of the connecting portion 39 in Figure 9A. 10 is a side sectional view showing the structure of a modification of another embodiment of this invention shown in FIGS. 9A and 9B, and FIG. 11 is a modification of the support member of one embodiment of this invention FIG. 2 is a perspective view showing an example configuration. 2, 30...load cell, 3...strain gauge,
4...Support leg, 5...Load detection section, 15, 16...Support member, 17...Connection member, 18...Liner, 19a...
Bolt, 19b...Nut, 20...Spacer, 21
...Liner, 22...Spacer, 24a...Bolt, 2
4b...Nut, 39...Connection part, 46...Bolt, 4
7...Parts.

Claims (1)

[Claims for Utility Model Registration] (1) In a platform weighing device having a plurality of load detection units that detect a load applied to one end of a load cell using a strain gauge provided on the load cell, the platform scale device is vertically spaced apart and parallel to each other. a plurality of pairs of flexible elongated plate-shaped support members arranged in the
and a connecting member that interconnects the proximal ends of the plurality of pairs of support members, and the other end of each of the load cells is supported by each tip of each of the pairs of support members. Platform weighing device. (2) The platform scale device according to claim 1, which is a registered utility model, characterized in that an adjustment mechanism is provided to adjust the distance between each of the load detection sections and the connection member.