JPH051802Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The disclosed technology is for the structure of a strain-generating body of a load cell that supports and measures the weight of a weighing pan of a scale, such as one installed on the desk of a cash register in a supermarket. Belongs to the technical field.

<Summary of the gist> The invention of this application is to provide mounting holes for screws on the base of the table-top scale, etc. and mounting holes for screws on the plate holder of the weighing pan at both ends in the length direction. At the same time, H-shaped strain holes are penetrated through the sides, and strain gauges are attached to both upper and lower sides of the strain section.Weighing pans are placed on both sides of the strain section in the longitudinal direction so as not to affect the rated strain. This is a device for a load cell strain body structure in which a notch is formed to remove the torsional moment on the threaded part when a biased load is applied to the strain gauge. This invention relates to a strain-generating body structure of a load cell, which has a closed cross section and is formed into a circular shape in plan view with a set depth.

<Prior art> As is well known, various products in the secondary market are often weighed during handling, and in that case, the applied load of a weighing device is replaced by mechanical measurement using a spring or the like. So-called load cell type measuring devices that electrically convert strain to accurately measure it have become widely used.For example, in supermarkets, etc., weighing measuring devices with a weighing pan installed on the countertop of the register are used. is widely used.

In this case, the load applied to the weighing pan is applied to a strain-generating body made of metal such as aluminum, and the mechanical strain of the metal body in microns is electrically measured. To briefly explain with reference to Fig. 5, an aluminum strain-generating body 3 having an H-shaped strain hole 4 penetrating through the base 1 of the scale approximately at the center of the side thereof is connected to a screw hole 5 (not shown) on the base side thereof. At the same time, a pan holder 6 is fixed on the other side with a screw (not shown) through the screw hole 7, a weighing pan 8 is installed on the pan holder 6, and a product (not shown) is placed on the pan holder 6, and the applied load is applied. The strain generated in the strained portion of the strained hole 4 of the strain-generating body 3 is electrically measured by a Wheatstone bridge circuit via strain gauges 9 attached to the upper and lower surfaces of the strained portion.

Since the strain-generating body 3 is hardly affected by vertical loads, recently, as measuring devices such as scales have become more compact, the mounting of the strain-generating body 3 on the base 1 has been changed from the conventional method. Instead of the horizontal screw type cantilever type, the size is reduced by mounting in the vertical direction as shown in FIG.

In this seed scale, since the weighing pan 8 is generally larger than the strain-generating body 3, the product is not necessarily placed on the central part of the weighing pan 8 to measure the applied load. In actual handling, the product is placed in the center of the weighing pan 8 as much as possible, but if the product is applied to a location that is biased to one of the four corners. In such a case, depending on the deflection position, a torsional moment often acts on the strain-generating body 3, especially on the screw part that is attached to the base 1, and the torsional moment is Due to the presence of residual traces, zero point return may not always be stable over time, and this is not desirable for scales that require sophistication. Therefore, zero point return must always be stable during manufacturing. becomes necessary.

In order to deal with the instability of zero point return caused by the torsional moment caused by the load applied by placing the product on the weighing pan in a deviated position, the measures shown in Figs. 6 and 7 are taken. It was getting worse.

<Problem to be solved by the invention> That is, on both sides of the strain part of the strain body 3 in the longitudinal direction from the attachment part of the strain gauge 9, that is, in the part that does not interfere with the rated strain due to the strain hole 4. A pair of torsional moment removal notches 10, 10 on one side are formed in a slot shape so as to traverse in the lateral direction, and the torsional moment on the surface of the strain-generating body 3 caused by the biased load applied on the weighing pan 8 is removed. By removing the distortion due to this, a stable return to zero point was obtained.

However, the slot-shaped torsional moment removal notch 10 has the disadvantage that it requires accurate positioning and complicated machining control to maintain an orthogonal traverse shape, and it is extremely difficult to machining it, making it impossible to achieve the precision as designed. If proper perforations are not formed, there is a drawback that stable zero point return as originally designed for the torsional moment removal notch cannot be achieved, and the cost increases as a result of the large amount of management and man-hours required. However, there was a disadvantage that if there was a processing error, the product yield would be poor.

As for the torsion moment removal notch 10, which is formed straight from the start end to the end end by traversing the upper and lower surfaces of the strain body 3, there is no risk of breakage or the like when an extreme impact load is applied. Even so, there have been problems such as adverse effects on durability performance etc. when frequent impact loads are applied over time.

<Purpose of the invention> The purpose of the invention of this application is to obtain a zero point due to a torsional moment through a bias load to a weighing pan with respect to a mounting screw to a base of a strain-generating body that forms the center of a load cell of a weighing device based on the above-mentioned prior art. The problem of unstable return is a technical issue to be solved, and while taking advantage of the torsional moment elimination notch formed on the outside of the strained hole, management and complicated man-hours for forming the torsional moment elimination notch are unnecessary. The present invention aims to provide an excellent strain-generating body structure for a load cell that can be formed smoothly through simple processing, has a good product yield, and can be manufactured at low cost, thereby benefiting the field of weighing technology in the distribution industry. .

<Means/effects for solving the problem> In line with the above-mentioned purpose, the structure of the invention of this application, which is summarized in the claims for the above-mentioned utility model registration, is to solve the above-mentioned problem by placing a product on a weighing pan of a scale, etc. When measuring the weight electrically using a strain gauge through the strain in the strain hole of the strain body, even if a biased load is applied to the weighing pan, etc., the outside of the strain gauge The torsional moment removal notches, which are circular in plan view and whose lateral cross section is a closed cross section, are provided on both sides of the strained portion in the longitudinal direction at locations that do not affect the rated strain. The torsional moment does not reach the attached part of the strain gauge, so
A technical measure that improves the reliability of the scale by guaranteeing a stable return to zero when the product is removed and unloaded from the weighing pan, ensuring accurate weighing at all times. It is.

<Example> Next, an example of the invention of this application will be described below based on FIGS. 1 to 4. Furthermore, the fifth
7 to 7 will be described using the same reference numerals.

The embodiment shown in FIGS. 1 to 3 is an embodiment of the aluminum strain body 3' of the load cell of the scale with a weighing pan shown in FIG. As shown in FIGS. 6 and 7, an H-shaped strain hole 4 is provided approximately at the center of both sides of the strain hole 4, and the thin wall portion of the strain hole 4 is used as a measuring portion to which a strain gauge 9 is attached. ing.

Attachment holes 5, 5 for bolts (not shown) to the base, and attachment holes 7, 7 for plate receiving screws of the support of the weighing plate are bored at both ends in the length direction.

In the invention of this application, in the figure, both sides of the strain hole 4 on the upper and lower surfaces, that is, the strain gauge 9
A pair of torsion moment removing notches 11, 11, which are circular in plan view and have a closed cross section, are bored on each side at predetermined positions that do not affect the rated strain on the outer side of the strained portion of the attached portion.

Therefore, each torsion moment removal notch 11
The size of the strain-generating body 3' is determined in advance based on the purpose of the scale, properties, etc.

Of course, the torsional moment removing notch 11 has been designed based on theory and experiments to remove the torsional moment and always obtain stable zero point return even if a biased load is applied to the weighing pan. There is.

Note that 12 is an insertion hole for a lead wire to the strain gauge.

Further, the torsion moment removing notch 11 is naturally located at a position that does not affect the rated strain of the strain hole 4 of the strain body 3'.

In the above configuration, similarly to the embodiment shown in FIG.
A predetermined product is appropriately placed on the weighing pan 8 via the pan holder 6 of the support, and the weight is applied to cause strain in the strain body 3', which causes strain attached to the measurement part of the strain hole 4 to be applied. The strain is converted into an electric signal through the Wheatstone bridge circuit by the gauge 9 and the weight is measured, but in this case, a biased load is applied due to the product being placed on a biased portion of the weighing pan 8. Even if a torsional moment remains in the strain body 3',
The torsional moment is removed by the torsional moment removal notches 11, 11, . . . and does not affect the attached part of the strain gauge 9. Therefore, stable zero point return can always be obtained by unloading by removing the product. , the function of the scale is always maintained exactly as designed.

Of course, in the torsion moment removal notch 11 of the invention of this application, since the strain body 3' does not traverse in the lateral direction to the attachment portion of the strain gauge 9, the unexpected impact load caused by the product to the weighing pan 8 is repeatedly caused. Even when applied with
Of course, there is no risk of breakage, and there is no risk of micro-cracks occurring due to fatigue, so durability is reliably guaranteed.

In the embodiment shown in FIG. 4, a pair of torsional moment removing notches 11 are provided in one region, that is, eight torsional moment removing notches 11 are provided in the entire strain body 3'. A shape in which the torsional moment removing notch 11 does not traverse in the lateral direction in the measurement section provides the same effect as the above-mentioned embodiment, and also contributes to reducing the weight of the load cell.

It goes without saying that the embodiments of the invention of this application are not limited to the above-mentioned embodiments. For example, the torsional moment removal notch may be filled with a flexible resin material to prevent dirt from adhering to it. Various aspects can be adopted, such as

In addition, in terms of design changes, the torsional moment removal notch may be formed by doubling elliptical or circular notches in plan view, or may be formed with a stepped portion in the depth direction. It goes without saying that various aspects can be adopted.

It goes without saying that the present invention can be applied not only to desk scales at supermarket registers, but also to, for example, weighing hoppers of multiple heads of a combination weighing device.

<Effect of the invention> As described above, according to the invention of this application, basically, in the strain-generating body structure of a load cell installed in a tabletop scale, etc., the rating on both sides of the outside of the strained part of the strain gauge attached part of the strained hole is By drilling a torsion moment removal notch with a horizontally closed cross section, such as a circular shape in plan view, in a part that does not affect strain, the torsional moment is removed from the strain body through the support during repeated weighing. Even if a torsional moment occurs due to the biased load of the object to be weighed, no torsional moment will be applied to the strain gauge, ensuring a stable zero point return at all times when unloading, and improving reliability of the weighing device. It is played.

Further, the rated strain of the measurement strain of the flexure element with respect to the strain gauge is not affected in any way, and therefore, the overall performance of the scale is further improved and the reliability is increased.

Furthermore, the provision of the torsional moment removal notch facilitates the weight reduction of the strain-generating body, which, together with the compactness, promotes the weight reduction of the weighing device, which also has the effect of reducing the amount of materials used.

Also, since it does not have a torsion moment removal notch that traverses in the lateral direction like the conventional type,
Even if repeated impact loads are applied, even if the product does not break, it may develop microscopic cracks that are invisible to the naked eye over time, causing changes in performance.
An excellent effect is achieved without adversely affecting durability.

Furthermore, since the lateral closed cross section is a closed cross section, it is possible to form a counterbore hole with a drill, unlike the conventional slotted type of torsion moment removal notch, making it easier to form the hole and reducing the number of man-hours. It has the advantage of being small in number, easy to manage and control, simple and low cost.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams of an embodiment of the invention of this application, in which FIG. 1 is a schematic perspective view of one embodiment, FIG. 2 is a plan view of the same, FIG. 3 is a longitudinal sectional view of the same, and FIG. The figure is a plan view of another embodiment, FIG. 5 is a schematic mechanical side view of a conventional scale, FIG. 6 is a plan view of a strain-generating body based on the prior art, and FIG. 7 is a side view of the same. DESCRIPTION OF SYMBOLS 1... Base, 6... Support body, 5, 7... Mounting hole, 4... Strain hole, 9... Strain gauge, 11...
...Torsional moment removal notch, 3'...Strain body.

Claims (1)

[Claims for Utility Model Registration] (1) It has mounting holes for the base and support at both ends, has a strain hole through it approximately in the center, and has torsion moment removal notches formed on both sides of the strain gauge attachment area. In the strain-generating body structure, the torsional moment removing notches are formed in a horizontally closed cross-section at a set depth at a portion on both sides in the longitudinal direction from the strained portion of the strained hole portion and do not affect the rated strain. The strain-generating body structure of the load cell is characterized by: (2) The strain-generating body structure of a load cell according to claim 1, wherein the torsional moment removing notch is formed with a step in the depth direction. (3) The strain-generating body structure of a load cell according to claim 1, wherein the torsional moment removing notch is circular in plan view and doubles in the lateral direction.